System and method for improving safety features in electrochemical cells
阅读说明：本技术 用于改进电化学电池中的安全特征的系统和方法 (System and method for improving safety features in electrochemical cells ) 是由 福岛孝明 R·霍尔曼 R·巴扎雷拉 M·R·泰勒 太田直树 于 2018-02-01 设计创作，主要内容包括：本文描述的实施例总体上涉及用于改进电化学电池中的安全特征的系统和方法。尤其,如本文描述的系统和方法可以解决与电化学电池中的气体产生有关的安全问题。电化学电池包括壳体,所述壳体包括具有第一密封区域的第一部分和具有第二密封区域的第二部分。(Embodiments described herein relate generally to systems and methods for improving safety features in electrochemical cells. In particular, the systems and methods as described herein may address safety issues related to gas generation in electrochemical cells. An electrochemical cell includes a housing including a first portion having a first sealing region and a second portion having a second sealing region.)
1. An apparatus, comprising:
a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region,
the first portion of the housing is configured to partially define a first cavity configured to receive a cathode and the second portion of the housing is configured to partially define a second cavity configured to receive an anode;
a separator disposed between the cathode and the anode, and coupled to a portion of the first seal region and a portion of the second seal region; and
a fluid flow path disposed between a portion of the first seal portion and the second seal portion, and configured to allow gas generated during operation of the electrochemical cell to flow from at least one of the first cavity and the second cavity to an area outside the housing.
2. The apparatus of claim 1, further comprising:
a third cavity fluidly coupled to at least one of the first cavity and the second cavity, the third cavity configured to receive the gas generated during operation of the electrochemical cell.
3. The apparatus of claim 1, wherein the third cavity is external to the housing.
4. The apparatus of claim 2, wherein the third cavity is fluidly coupled to at least one of the first and second cavities in a first configuration and fluidly isolated from the first and second cavities in a second configuration.
5. The apparatus of claim 4, wherein the third lumen is configured to be removable from the housing in the second configuration.
6. The apparatus of claim 2, wherein the third cavity has a volume between about 5% to about 50% of the volume of the housing.
7. The apparatus of claim 1, wherein a portion of the separator extends through the first and second seal regions to form the fluid flow path from at least one of the first and second cavities to an area outside of the housing.
8. The apparatus of claim 7, wherein the portion of the separator forming the fluid flow path is porous.
9. The apparatus of claim 8, wherein the fluid flow path is configured to fluidly communicate the gas without interfering with normal operation of the electrochemical cell.
10. The apparatus of claim 8, wherein the porous portion of the separator has a porosity of about 1% to about 90%.
11. The apparatus of claim 8, wherein the porous portion of the separator has pores with a size of about 1 μ ι η to about 200 μ ι η.
12. An apparatus, comprising:
a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region,
the first portion of the housing is configured to partially define a first cavity configured to receive a cathode and the second portion of the housing is configured to partially define a second cavity configured to receive an anode;
a separator disposed between the cathode and the anode, and coupled to a portion of the first seal region and a portion of the second seal region; and
a safety mechanism operably coupled to the electrochemical cell and configured to terminate electrical operation of the electrochemical cell when a gas pressure within at least one of the first cavity and the second cavity exceeds a threshold.
13. The apparatus of claim 12, wherein the safety mechanism comprises a thinned portion of the housing configured to open when the gas pressure within at least one of the first and second cavities exceeds the threshold.
14. The apparatus of claim 13, wherein the threshold gas pressure is between about 5psi and about 2000 psi.
15. The apparatus of claim 13, wherein a threshold gas pressure is greater than about 40% of a predicted gas pressure at which the electrochemical cell abruptly fails.
16. The apparatus of claim 13, wherein the thinned portion has a thickness ratio of less than about 0.5 compared to other portions of the housing.
17. The apparatus of claim 12, wherein the safety mechanism comprises a circuit interrupting device configured to disconnect the electrochemical cell from a circuit when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold.
18. The apparatus of claim 17, further comprising:
a cathode tab electrically coupled to the cathode; and
an anode tab electrically coupled to the anode,
wherein the circuit interrupting device comprises a narrowed portion formed in at least one of the cathode tab and the anode tab, the narrowed portion configured to rupture when the gas pressure within at least one of the first cavity and the second cavity exceeds the threshold.
19. The apparatus of claim 12, wherein the cathode is electrically coupled to a cathode current collector, and the safety mechanism is configured to physically separate the cathode from at least one of the cathode current collector and the separator when the gas pressure within at least one of the first cavity and the second cavity exceeds the threshold, thereby terminating electrical operation of the electrochemical cell.
20. The apparatus of claim 12, wherein the anode is electrically coupled to an anode current collector, and the safety mechanism is configured to physically separate the anode from at least one of the anode current collector and the separator when the gas pressure within at least one of the first and second cavities exceeds the threshold, thereby terminating electrical operation of the electrochemical cell.
21. An apparatus, comprising:
a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region,
the first portion of the housing is configured to partially define a first cavity configured to receive a cathode and the second portion of the housing is configured to partially define a second cavity configured to receive an anode; and
a separator disposed between the cathode and the anode and coupled to the first and second seal regions, a portion of the separator extending through the first and second seal regions to create a fluid flow path from at least one of the first and second cavities to a region outside the housing.
22. The apparatus of claim 21, wherein the portion of the separator forming the fluid flow path is porous.
23. The apparatus of claim 22, wherein the porous portion of the separator has a porosity of about 1% to about 90%.
24. The apparatus of claim 22, wherein the porous portion of the separator has pores with a size of about 1 μ ι η to about 200 μ ι η.
25. The apparatus of claim 22, wherein the porous portion of the separator is configured to allow gas generated during operation of the electrochemical cell to flow from at least one of the first cavity and the second cavity to a region outside of the housing.
26. The apparatus of claim 25, wherein the fluid flow path is configured to fluidly communicate the gas without interfering with normal operation of the electrochemical cell.
27. The apparatus of claim 25, wherein the gas is formed during formation of the electrochemical cell, during normal operation of the electrochemical cell, and when the gas pressure within the housing exceeds a threshold.
28. The apparatus of claim 27, wherein the threshold gas pressure is between about 5psi and about 2000 psi.
29. The apparatus of claim 27, wherein a threshold gas pressure is greater than about 40% of a predicted gas pressure at which the electrochemical cell abruptly fails.
Background
While lithium ion batteries (or electrochemical cells) have become popular, consumer safety of these devices has also become critical. In conventional operation, an electrochemical reaction occurs inside a lithium ion battery to generate electricity. These reactions also produce by-products. In particular, the gaseous products generated during the formation, operation and storage of lithium ion batteries present significant technical challenges. The gas released during formation requires an additional degassing process, thereby increasing production costs. Gas evolution during the resulting battery cycle, especially under overcharge conditions, can lead to internal pressure build-up, performance degradation, and potential safety failures. Gas generation during storage, especially at elevated temperatures, can lead to a reduced shelf life of the product. Difficulties are also challenging for batteries packaged in soft foil laminated plastic due to potentially detrimental dimensional changes and package breakage.
Disclosure of Invention
Embodiments described herein relate generally to systems and methods for improving safety features in electrochemical cells. In particular, the systems and methods described herein may address safety issues related to gas generation in electrochemical cells.
In certain embodiments, an apparatus includes a housing for an electrochemical cell, the housing including a first portion having a first sealing region and a second portion having a second sealing region. The first portion of the housing may be configured to partially define a first cavity configured to receive a cathode, and the second portion of the housing may be configured to partially define a second cavity configured to receive an anode. A separator is disposed between the cathode and the anode, and the separator is coupled to a portion of the first seal region and a portion of the second seal region. A fluid flow path is disposed between a portion of the first seal portion and the second seal portion, and the fluid flow path is configured to allow gas generated during operation of the electrochemical cell to flow from at least one of the first cavity and the second cavity to an area outside of the housing.
In certain embodiments, the apparatus may include a third cavity fluidly coupled with at least one of the first cavity and the second cavity, the third cavity configured to receive the gas generated during operation of the electrochemical cell. In certain embodiments, the third cavity is external to the housing. In certain embodiments, the third cavity is fluidly coupled to at least one of the first and second cavities in a first configuration and is fluidly isolated from the first and second cavities in a second configuration. In certain embodiments, the third cavity is configured to be removable from the housing in the second configuration. In certain embodiments, the third cavity has a volume that is between about 5% to about 50% of the volume of the housing.
In certain embodiments, the apparatus is configured such that the separator extends through the first and second seal regions to form the fluid flow path from at least one of the first and second cavities to the region outside the housing. In certain embodiments, the portion of the separator forming the fluid flow path is porous. In certain embodiments, the fluid flow path is configured to fluidly communicate the gas without interfering with normal operation of the electrochemical cell. In certain embodiments, the porous portion of the separator has a porosity of about 1% to about 90%. In certain embodiments, the porous portion of the separator has pores with a size of about 1 μm to about 200 μm.
In certain embodiments, the device comprises a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region. The first portion of the housing is configured to partially define a first cavity configured to receive a cathode, and the second portion of the housing is configured to partially define a second cavity configured to receive an anode. A separator is disposed between the cathode and the anode, and the separator is coupled to a portion of the first seal region and a portion of the second seal region.
In certain embodiments, the apparatus may include a safety mechanism operably coupled to the electrochemical cell and configured to terminate electrical operation of the electrochemical cell when a gas pressure within at least one of the first cavity and the second cavity exceeds a threshold. In certain embodiments, the safety mechanism may include a thinned portion of the housing configured to open when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold. In certain embodiments, the threshold gas pressure is between about 5psi and about 2000 psi. In certain embodiments, the threshold gas pressure is greater than about 40% of a predicted gas pressure that would abruptly fail the electrochemical cell. In certain embodiments, the thinned portion has a thickness ratio of less than about 0.5 compared to other portions of the housing.
In certain embodiments, the safety mechanism may include a circuit interrupting device configured to disconnect the electrochemical cell from the electrical circuit when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold. In certain embodiments, the apparatus further comprises a cathode tab (tab) electrically coupled to the cathode and an anode tab electrically coupled to the anode. In some embodiments, the circuit interrupting device may include a narrowed portion formed in at least one of the cathode tab and the anode tab, the narrowed portion configured to rupture when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold.
In certain embodiments, the apparatus is configured such that the cathode is electrically coupled to a cathode current collector and the safety mechanism is configured to physically separate the cathode from at least one of the cathode current collector and the separator when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold, thereby terminating electrical operation of the electrochemical cell.
In certain embodiments, the apparatus is configured such that the anode is electrically coupled to an anode current collector and the safety mechanism is configured to physically separate the anode from at least one of the anode current collector and the separator when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold, thereby terminating electrical operation of the electrochemical cell.
In certain embodiments, the device comprises a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region. The first portion of the housing is configured to partially define a first cavity configured to receive a cathode, and the second portion of the housing is configured to partially define a second cavity configured to receive an anode. A separator is disposed between the cathode and the anode and coupled to the first and second seal regions, a portion of the separator extending through the first and second seal regions to create a fluid flow path from at least one of the first and second cavities to a region outside the housing.
In certain embodiments, the portion of the separator forming the fluid flow path is porous. In certain embodiments, the porous portion of the separator has a porosity of about 1% to about 90%. In certain embodiments, the porous portion of the separator has pores with a size of about 1 μm to about 200 μm. In certain embodiments, the porous portion of the separator is configured to allow gas generated during operation of the electrochemical cell to flow from at least one of the first cavity and the second cavity to the region outside the housing. In certain embodiments, the fluid flow path is configured to fluidly communicate the gas without interfering with normal operation of the electrochemical cell. In certain embodiments, the gas is formed during formation of the electrochemical cell, during normal operation of the electrochemical cell, and at least one of when the gas pressure within the housing exceeds a threshold value. In certain embodiments, the threshold gas pressure is between about 5psi and about 2000 psi. In certain embodiments, the threshold gas pressure is greater than about 40% of a predicted gas pressure that would abruptly fail the electrochemical cell.
Drawings
Fig. 1A-1C show schematic diagrams of an electrochemical cell including a vent for releasing gases generated during operation of the cell, according to an embodiment.
Fig. 2A-2C show schematic diagrams of electrochemical cells that use porous separators to release gases generated during operation of the cell, according to embodiments.
Fig. 3 shows a schematic diagram of an electrochemical cell including an auxiliary pouch to absorb gas and regulate gas pressure within the cell, according to an embodiment.
Fig. 4A-4C show schematic diagrams of an electrochemical cell including a single pouch circuit interrupting device to protect the cell from overpressure due to gas generation, according to an embodiment.
Fig. 5 shows a schematic of an electrochemical cell including a needle within a cell housing to protect the cell from overpressure, according to an embodiment.
Fig. 6A-6C illustrate schematic diagrams of a layered safety mechanism employing electrodes, according to some embodiments.
Detailed Description
Embodiments described herein relate generally to systems and methods for improving safety features in electrochemical cells. In particular, the systems and methods described herein may improve safety with respect to gas generation in an electrochemical cell.
Gas generation due to electrolyte decomposition is often one of the major problems of high performance rechargeable batteries, especially lithium ion ("Li-ion") based batteries. For example, continuous gassing due to oxidation and reduction of electrolyte solvents is at high pressures of LiN10.5Mn1.5O4Graphite pouch cells. In addition, metal dissolution in the electrolyte and decomposition products caused by high potentials can have a detrimental effect on gas generation, especially during the first charge cycle (i.e., during formation of the graphite solid-electrolyte interface layer).
Among the various designs of lithium ion batteries, pouch batteries are widely used because they are flexible and lightweight, and can achieve high packaging efficiency (e.g., about 90% to 95%). In a typical pouch battery, conductive foil tabs are welded to the electrodes and sealed to the pouch to bring the positive and negative terminals of the pouch to the outside of the pouch.
In pouch batteries, gas generation can cause swelling, and pressure from the swelling can rupture the battery cover to open and in some cases disconnect the display or electronic circuitry. Conventionally, manufacturers add excess film to create an "air pocket" on the outside of the pouch cell to contain the gas during the first charge. The bladder may then be severed and the package released as part of the finishing process. However, this approach does not address the problem of gas accumulation during subsequent charging, particularly after delivery of the battery to the customer.
In certain embodiments, an apparatus includes a housing for an electrochemical cell, the housing including a first portion having a first sealing region and a second portion having a second sealing region. The first portion of the housing may be configured to partially define a first cavity configured to receive a cathode, and the second portion of the housing may be configured to partially define a second cavity configured to receive an anode. A separator is disposed between the cathode and the anode, and the separator is coupled to a portion of the first seal region and a portion of the second seal region. A fluid flow path is disposed between a portion of the first seal portion and the second seal portion, and the fluid flow path is configured to allow gas generated during operation of the electrochemical cell to flow from at least one of the first cavity and the second cavity to an area outside of the housing.
In certain embodiments, the apparatus may include a third cavity fluidly coupled with at least one of the first cavity and the second cavity, the third cavity configured to receive the gas generated during operation of the electrochemical cell. In certain embodiments, the third cavity is external to the housing. In certain embodiments, the third cavity is fluidly coupled to at least one of the first and second cavities in a first configuration and is fluidly isolated from the first and second cavities in a second configuration. In certain embodiments, the third cavity is configured to be removable from the housing in the second configuration. In certain embodiments, the third cavity has a volume that is between about 5% to about 50% of the volume of the housing.
In certain embodiments, the apparatus is configured such that the separator extends through the first and second seal regions to form the fluid flow path from at least one of the first and second cavities to the region outside the housing. In certain embodiments, the portion of the separator forming the fluid flow path is porous. In certain embodiments, the fluid flow path is configured to fluidly communicate the gas without interfering with normal operation of the electrochemical cell. In certain embodiments, the porous portion of the separator has a porosity of about 1% to about 90%. In certain embodiments, the porous portion of the separator has pores with a size of about 1 μm to about 200 μm.
In certain embodiments, the device comprises a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region. The first portion of the housing is configured to partially define a first cavity configured to receive a cathode, and the second portion of the housing is configured to partially define a second cavity configured to receive an anode. A separator is disposed between the cathode and the anode, and the separator is coupled to a portion of the first seal region and a portion of the second seal region.
In certain embodiments, the apparatus may include a safety mechanism operably coupled to the electrochemical cell and configured to terminate electrical operation of the electrochemical cell when a gas pressure within at least one of the first cavity and the second cavity exceeds a threshold. In certain embodiments, the safety mechanism may include a thinned portion of the housing configured to open when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold. In certain embodiments, the threshold gas pressure is between about 5psi and about 2000 psi. In certain embodiments, the threshold gas pressure is greater than about 40% of a predicted gas pressure that would abruptly fail the electrochemical cell. In certain embodiments, the thinned portion has a thickness ratio of less than about 0.5 compared to other portions of the housing.
In certain embodiments, the safety mechanism may include a circuit interrupting device configured to disconnect the electrochemical cell from the electrical circuit when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold. In certain embodiments, the apparatus further comprises a cathode tab electrically coupled to the cathode and an anode tab electrically coupled to the anode. In some embodiments, the circuit interrupting device may include a narrowed portion formed in at least one of the cathode tab and the anode tab, the narrowed portion configured to rupture when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold.
In certain embodiments, the apparatus is configured such that the cathode is electrically coupled to a cathode current collector and the safety mechanism is configured to physically separate the cathode from at least one of the cathode current collector and the separator when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold, thereby terminating electrical operation of the electrochemical cell.
In certain embodiments, the apparatus is configured such that the anode is electrically coupled to an anode current collector and the safety mechanism is configured to physically separate the anode from at least one of the anode current collector and the separator when a gas pressure within at least one of the first cavity and the second cavity exceeds the threshold, thereby terminating electrical operation of the electrochemical cell.
In certain embodiments, the device comprises a housing for an electrochemical cell, the housing comprising a first portion having a first sealing region and a second portion having a second sealing region. The first portion of the housing is configured to partially define a first cavity configured to receive a cathode, and the second portion of the housing is configured to partially define a second cavity configured to receive an anode. A separator is disposed between the cathode and the anode and coupled to the first and second seal regions, a portion of the separator extending through the first and second seal regions to create a fluid flow path from at least one of the first and second cavities to a region outside the housing.
In certain embodiments, the portion of the separator forming the fluid flow path is porous. In certain embodiments, the porous portion of the separator has a porosity of about 1% to about 90%. In certain embodiments, the porous portion of the separator has pores with a size of about 1 μm to about 200 μm. In certain embodiments, the porous portion of the separator is configured to allow gas generated during operation of the electrochemical cell to flow from at least one of the first cavity and the second cavity to the region outside the housing. In certain embodiments, the fluid flow path is configured to fluidly communicate the gas without interfering with normal operation of the electrochemical cell. In certain embodiments, the gas is formed during formation of the electrochemical cell, during normal operation of the electrochemical cell, and at least one of when the gas pressure within the housing exceeds a threshold value. In certain embodiments, the threshold gas pressure is between about 5psi and about 2000 psi. In certain embodiments, the threshold gas pressure is greater than about 40% of a predicted gas pressure that would abruptly fail the electrochemical cell.
In certain embodiments, an electrochemical cell structure is designed to remove excess gas during the cell formation stage. In certain embodiments, an electrochemical cell structure is placed with strategically placed vent holes designed to relieve increased pressure caused by gases generated during normal operating conditions of the electrochemical cell. In certain embodiments, an electrochemical cell structure is strategically sealed with an engineered separator within a laminated electrode designed to relieve increased pressure caused by gases generated during normal operating conditions of the electrochemical cell. In certain embodiments, a safety mechanism is employed to delaminate the electrodes to treat electrochemical cells that exceed a predetermined pressure threshold. In certain embodiments, a safety mechanism is employed to include an engineered fuse to terminate the electrical connection at the connector tab for handling electrochemical cells that exceed a predetermined pressure threshold. In certain embodiments, a safety mechanism is employed to prevent catastrophic failure in an electrochemical cell by employing strategically placed pins in a can cell or a cell holder that includes a pouch cell.
As used herein, the terms "about" and "approximately" generally mean plus or minus 10% of the stated value, e.g., about 250 μm would comprise 225 μm to 275 μm, and about 1000 μm would comprise 900 μm to about 1100 μm.
Fig. 1A-1C show schematic diagrams of an electrochemical cell 100, the electrochemical cell 100 including gas vent holes (also referred to simply as vents) to address gas generation and potentially high pressures in the cell. The method may be used at various stages of its production and service life.
Electrochemical cell 100 includes a cathode 110 (also referred to as a cathode material) disposed on a cathode current collector 112, an anode 120 (also referred to as an anode material) disposed on an anode current collector 122, and a separator 130 disposed therebetween. The assembly of cathode 110, cathode current collector 112, anode 120, anode current collector 122, and separator 130 may be substantially contained within a pouch 140, the pouch 140 sealed along a sealed perimeter 142. The cathode tab 115 may be electrically connected to the cathode current collector 112 and extend beyond the pocket 140 for connection with an external circuit. Similarly, anode tab 125 is electrically connected to anode current collector 115 and extends beyond bag 140 for connection with an external circuit. In certain embodiments, the cathode tab 115 may be a portion of the cathode current collector 112 extending from the sealing perimeter 142, and the anode tab 125 may be a portion of the anode current collector 122 extending from the sealing perimeter 142. In other words, cathode tab 115 and anode tab 125 may be integrally formed with their respective current collectors. The pouch 140 can separate the electrochemical cell 100 from an adjacent cell or cells in a battery module or pack, thereby mitigating defect propagation and fire hazard. Electrochemical cell 100 also includes a vent 145 on the cathode side of pouch 140 to release gases generated during testing and/or operation of electrochemical cell 100, thereby regulating the pressure within pouch 140.
In certain embodiments, the cathode material 110 may include, for example, Nickel Cobalt Aluminum (NCA), Core Shell Gradient (CSG), spinel based lithium ion (LMO), lithium iron phosphate (LFP), cobalt based lithium ion (LCO), Nickel Cobalt Manganese (NCM), and the like.
The anode material 120 may be selected from a variety of materials. In certain embodiments, the anode material 120 comprises carbon-based materials including, but not limited to, hard carbon, carbon nanotubes, carbon nanofibers, porous carbon, and graphene. In certain embodiments, the anode material 120 comprises a titanium-based oxide, including, but not limited to, spinel Li4Ti5O12(LTO) and titanium dioxide (TiO)2Titanium dioxide). In certain embodiments, the anode material 120 comprises an alloy or an unalloyed material including, but not limited to, silicon monoxide (SiO), germanium, and tin oxide (SnO)2). In certain embodiments, the anode material 120 includes a transition metal compound (e.g., oxides, phosphides, sulfides, and nitrides). The general formula of the transition compound can be written as MxNyWherein M may be selected from iron (Fe), cobalt (Co), copper (Cu), manganese (Mn), and nickel (Ni), and N may be selected from oxygen (O), phosphorus (P), sulfur (S), and nitrogen (N).
In certain embodiments, the anode material 120 includes an intermetallic compound. The intermetallic compound may be based on the expression MM ', where M is one metal element and M' is a different metal element. The intermetallic compound may further include two or more metal elements. The M atom of the intermetallic compound may be, for example, Cu, Li, and Mn, and the M' element of the intermetallic compound may be, for example, Sb. Exemplary intermetallic compounds include Cu2Sb、Li2CuSb and Li3Sb, and the like. In one exampleThe intermetallic compound in the anode material may have a completely disordered structure in which M or M' atoms are arranged in a random manner. In another example, the intermetallic compound in the anode material has a partially disordered structure in which M or M' atoms in the crystal lattice are arranged in a non-random manner.
In certain embodiments, the anode material 120 may be porous, thereby increasing the surface area and increasing the rate of lithium intercalation reactions in the resulting electrode. In one example, the anode material 120 includes porous Mn2O3It may be prepared, for example, by MnCO3Thermal decomposition of the microspheres. In another example, the anode material 120 includes porous carbon fibers prepared by, for example, electrospinning a blended solution of polyacrylonitrile and poly (l-lactide) and then by carbonization. In certain embodiments, the porosity of the anode material 120 may be achieved or increased by using a porous current collector. For example, the anode material 120 may include Cu2Sb, which is uniformly deposited on the porous foam structure to have a certain degree of porosity.
In certain embodiments, at least one of the anode material 120 or the cathode material 110 can include a semi-solid or condensed ion-storing liquid reactant. The term "semi-solid" means that the material is a mixture of liquid and solid phases, e.g., a semi-solid, a particle suspension, a colloidal suspension, an emulsion, a gel, or a micelle. By "condensed ion storage liquid" or "condensed liquid" is meant that the liquid is not merely a solvent as in the case of an aqueous flow cell catholyte or anolyte, but is itself redox active. This liquid form may also be diluted or mixed with another non-redox active liquid that acts as a diluent or solvent, including mixing with such a diluent to form a low melting liquid phase, emulsion or micelle containing the ion storage liquid. In certain embodiments, the semi-solid electrode composition (also referred to herein as a "semi-solid suspension" and/or a "slurry") can include a suspension of electrochemically active agent (anode particles and/or cathode particles) and optionally electronically conductive particles. The cathode particles and the conductive particles are co-suspended in the electrolyte to produce a cathode semi-solid. The anode particles and the conductive particles are co-suspended in the electrolyte to produce an anode semi-solid. The semi-solid is able to flow due to applied pressure, gravity or other applied fields that exert a force on the semi-solid, and optionally by means of mechanical vibration. An example of a battery utilizing a SEMI-SOLID suspension is described in U.S. patent No.9,362,583 entitled "SEMI-SOLID ELECTRODES HAVING HIGH RATE CAPABILITY," the entire disclosure of which is incorporated herein by reference.
In some embodiments, one or both of the current collectors 112 and 122 may include a conductive substrate. In one example, the conductive substrate comprises a metallic material, such as aluminum, copper, lithium, nickel, stainless steel, tantalum, titanium, tungsten, vanadium, or combinations or alloys thereof. In another example, the conductive substrate comprises a non-metallic material, such as carbon, carbon nanotubes, or metal oxides (e.g., TiN, TiB)2、MoSi2、n-BaTiO3、Ti2O3、ReO3、RuO2、IrO2Etc.).
In certain embodiments, one or both of the current collectors 112 and 122 may include a base substrate with one or more surface coatings to improve the mechanical, thermal, chemical, or electrical properties of the current collectors. In one example, one or more coatings on the current collector may be configured to reduce corrosion and alter adhesion characteristics (e.g., hydrophilic or hydrophobic coatings, respectively). In another example, one or more coatings on the current collector may include a material of high conductivity to improve the overall charge transport of the base substrate. In yet another example, the coating may include a material of high thermal conductivity to facilitate heat dissipation from the base substrate and to protect the cell from overheating. In yet another example, the coating may include a heat or flame resistant material to prevent fire in the battery. In yet another example, the coating may be configured to be rough, thereby increasing the surface area and/or adhesion to the anode material. In yet another example, the coating may comprise a material having good adhesion or gluing properties with the anode material.
In certain embodiments, one or both of the current collectors 112 and 122 may include a conductive substrate having a roughened surface to improve the mechanical, electrical, and thermal contact between the anode material and the current collector. The roughened surface of the current collector may increase the physical contact area between the anode material and the current collector, thereby increasing the adhesion of the anode material to the current collector. The increased physical contact area may also improve electrical and thermal contact (e.g., reduced electrical and thermal resistance) between the current collector and the anode material.
In certain embodiments, one or both of the current collectors 112 and 122 may comprise a porous current collector, e.g., a wire mesh. The wire mesh (also referred to herein as a grid) may include any number of fine wire strands that may be assembled in various configurations using a suitable process, such as a regular pattern or structure produced by weaving, knitting, etc., or a more random pattern or structure produced by randomly distributing the strands and joining them by welding, adhesive, or other suitable technique. Furthermore, the wires comprising the grid may be of any suitable material. For example, in certain embodiments, the wire is metallic, e.g., steel, aluminum, copper, titanium, or any other suitable metal. In other embodiments, the wires may be a conductive, non-metallic material, such as carbon nanofibers or any other suitable material. In certain embodiments, the wire may include a coating. For example, the coating may be configured to reduce corrosion and enhance or reduce adhesion properties (e.g., hydrophilic or hydrophobic coatings, respectively). Examples OF POROUS CURRENT COLLECTORs are described in U.S. patent publication No. U.S.2013/0065122A1, entitled "SEMI-SOLID ELECTRODE CELL HAVING A POROUS CURRENT COLLECTOR AND APPARATUS AND METHOD OF MANUFACTURE," the entire disclosure OF which is incorporated herein by reference.
In certain embodiments, the separator 130 may be a thin microporous membrane that electrically isolates the anode 110 from the cathode 110, but allows ions to pass through the pores between the two electrolytes during discharge and charge. In certain embodiments, the separator 130 comprises a thermoplastic polymer, such as polyolefins, polyvinyl chloride, nylon, fluorocarbons, polystyrene, and the like. In certain embodiments, the separator 130 comprises a polyolefin material including, for example, polyethylene, ultra-high molecular weight polyethylene, polypropylene, polybutylene, polymethylpentene, polyisoprene, copolymers thereof, and combinations thereof. Exemplary compositions may include, but are not limited to, mixtures containing two or more of the following polyethylenes, ultrahigh molecular weight polyethylenes, and polypropylenes, as well as mixtures of the foregoing with copolymers such as ethylene-butene copolymers and ethylene-hexene copolymers.
The pouch 140 in the electrochemical cell 100 basically includes a cathode 110, a cathode current collector 112, an anode 120, an anode current collector 122 and a separator 130. The pouch 140 may physically separate the electrochemical cell 100 from adjacent electrochemical cells, thereby mitigating or eliminating defect propagation and facilitating easy handling of the electrochemical cell 100 during cell manufacture. The pouch 140 can also reduce the possibility of ignition of the combustible electrolyte during a potential welding process that sometimes produces sparks in battery manufacture when operated with semi-solid electrodes.
In certain embodiments, the cathode 110, the cathode current collector 112, the anode 120, the anode current collector 122, and the separator 130 are sealed in the pouch 140 (e.g., via vacuum sealing). In these embodiments, the pouch 140 may still reduce or eliminate the chance of exposure to sparks (e.g., from a welding process) that may ignite the electrolyte. A final sealing step may be performed after the welding process to seal one or more single pouch battery cells (single pouch battery cells) into an outer pouch or package, in which case the outer pouch or package may be used as a humidity control. An example OF a BATTERY architecture utilizing SINGLE POUCH CELLS is described in U.S. patent application publication No. u.s.2017-0025646a1, entitled "SINGLE POUCH BATTERY CELLS AND METHODS OF batteries," the entire disclosure OF which is incorporated herein by reference.
In certain embodiments, the pouch 140 comprises a three-layer structure, i.e., an intermediate layer sandwiched between an outer layer and an inner layer, wherein the inner layer is in contact with the electrodes and the electrolyte. For example, the outer layer may comprise a nylon-based polymer film. The inner layer may include a polypropylene (PP) polymer film, which may be resistant to acid corrosion or other electrolyte corrosion, and which is insoluble in an electrolyte solvent. The intermediate layer may include an aluminum (Al) foil. This structure gives the bag high mechanical flexibility and strength.
In certain embodiments, the outer layer of the bag 140 comprises a polymeric material, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylon, High Density Polyethylene (HDPE), oriented polypropylene (o-PP), polyethylene chloride (PVC), Polyimide (PI), Polysulfone (PSU), and combinations thereof.
In certain embodiments, the middle layer of the bag 140 comprises a metal layer (foil, substrate, film, etc.) comprising aluminum (Al), copper (Cu), stainless steel (SUS), alloys thereof, and combinations thereof.
In certain embodiments, the inner layer of the bag 140 comprises a material such as cast polypropylene (c-PP), Polyethylene (PE), Ethylene Vinyl Acetate (EVA), and combinations thereof.
In certain embodiments, the bag 140 comprises a double layer structure, i.e., an outer layer and an inner layer. In certain embodiments, the outer layer may comprise PET, PBT, or other materials as described above. In certain embodiments, the inner layer may comprise PP, PE, or other materials described above.
In certain embodiments, the bag 140 may include a water barrier layer and/or a gas barrier layer. In some embodiments, the barrier layer may include a metal layer and/or an oxide layer. In certain embodiments, it may be beneficial for the pouch 140 to include an oxide layer, as the oxide layer tends to be insulating and may prevent short circuits within the cell.
In certain embodiments, there may be only one (or two) cell assembly within the pouch 140, and the pouch 140 may be substantially thinner than pouches typically used for multi-stack cells. In certain embodiments, the pouch 140 may have a thickness of less than 200 μm, less than 100 μm, or less than 50 μm. In certain embodiments, the thickness of the bag 140 may be defined as the thickness of the film forming the bag 140.
In certain embodiments, the thickness of the bag 140 may depend on at least two aspects. In certain embodiments, it may be desirable to achieve a higher energy density in the resulting battery cell, in which case a thinner pouch may be helpful since a larger portion of the space within the battery cell may be reserved for electrode material. In certain embodiments, it may be desirable to maintain or improve the safety advantages of the bag 140. In certain embodiments, a thicker bag may help, for example, reduce the risk of fire. In certain embodiments, the pouch thickness may be quantified as the ratio of the volume occupied by the pouch material to the total volume of the battery cell. In certain embodiments, the bag thickness may be from about 5% to about 40% for the ratio as defined above. In certain embodiments, the bag thickness may be from about 10% to about 30% for the ratio as defined above.
In certain embodiments, the thickness of electrochemical cell 100 (including the thickness of pouch 140 and the thickness of the electrodes) may be about 300 μm to about 3mm (e.g., about 300 μm, about 400 μm, about 500 μm, about 1mm, about 2mm, or about 3mm, including any values and subranges therebetween).
In some embodiments, the bag 140 comprises a single layer of lower cost material that may be thinner. In certain embodiments, the lower cost material, which may be thinner, may be a polypropylene or polyolefin composition that may be sealed together using heat or pressure (e.g., heat fusion or vacuum sealing).
In certain embodiments, the pouch 140 comprises a single layer of fire retardant material, thereby preventing the risk of fire from propagating from one single pouch cell to another. In certain embodiments, the pouch 140 comprises a gas-tight material to prevent gases released by one single pouch cell from propagating to another, thereby reducing defect propagation.
The vent 145 in the bag 140 may be created in various ways. In certain embodiments, the vent 145 may result from a thinned portion on the cathode side of the bag 140. When gas is generated within the bag 140 and the gas pressure increases accordingly, the increased pressure may break the thinned portion of the bag, thereby forming an opening (i.e., a vent) in the bag 140.
The thickness of the thinned portion may depend on a desired threshold pressure at which the vent 145 may be created. In certain embodiments, the threshold pressure may be about 5psi to about 2000psi (e.g., about 5psi, about 10psi, about 20psi, about 50psi, about 100psi, about 200psi, about 500psi, about 1000psi, or about 2000psi, including any values and subranges therebetween). In certain embodiments, the threshold pressure may be about 10psi to about 1000psi (e.g., about 10psi, about 20psi, about 50psi, about 100psi, about 200psi, about 500psi, or about 1000psi, including any values and subranges therebetween). In certain embodiments, the threshold pressure may be about 2psi to about 50psi (e.g., about 20psi, about 30psi, about 40psi, or about 50psi, including any values and subranges therebetween).
In certain embodiments, the thinned portion can have a thickness of less than 100 μm (e.g., about 100 μm, about 90 μm, about 80 μm, about 70 μm, about 60 μm, about 50 μm, about 40 μm, about 30 μm, about 20 μm, or about 10 μm, including any values and subranges therebetween). In certain embodiments, the ratio of the thickness of the thinned portion compared to the thickness of other portions in the bag 140 may be less than 0.5 (e.g., about 0.5, about 0.4, about 0.3, about 0.2, or about 0.1, including any values and subranges therebetween).
In some embodiments, the vent 145 may be created by designated portions made of a different material than the material in other portions of the bag 140. For example, the designated portion may be made of a softer material such that increased pressure within the bag 140 may preferentially and selectively break the designated portion.
The vent 145 may have various shapes. In some embodiments, the vent 145 may be circular. In some embodiments, the vent 145 may be oval-shaped. In certain embodiments, the vent 145 may be rectangular or square. In some embodiments, the vent 145 may be a narrow strip opening in the bag 140.
In certain embodiments, the vent 145 may have a lateral dimension of about 1 μm to about 1mm (e.g., about 1 μm, about 5 μm, about 10 μm, about 20 μm, about 50 μm, about 100 μm, about 200 μm, about 500 μm, or about 1mm, including any values and subranges therebetween). In some embodiments, the area of the vent 145 may be about 1 μm2To about 1mm2(e.g., about 1 μm)2About 5 μm2About 10 μm2About 20 μm2About 50 μm2About 100 μm2About 200 μm2About 500 μm2Or about 1mm2Including thereinAny values and subranges thereof).
Fig. 1A to 1C show only one vent hole 145 for illustrative purposes. In practice, the electrochemical cell 100 may include more than one vent 145. In certain embodiments, the electrochemical cell 100 may include an array of vents.
In certain embodiments, the electrochemical cell 100 can include one or more vent holes 145 (opposite the sides of the tabs 115 and 125) at the bottom of the pouch 140. In certain embodiments, the vent 145 may be located at a side edge of the bag 140. In certain embodiments, the vent 145 may be located on the front surface of the cathode side of the bag 140.
In certain embodiments, the vent 145 may also include a support structure, such as a cross made of a rigid material, to keep the vent 145 open. For example, the bag 140 may be made of a soft material and the vent 145 may tend to collapse. The vent 145 may be kept open using a support structure.
In certain embodiments, the vent 145 may be sealable. For example, vent 145 may collapse back to a sealed state after the pressure within bag 140 drops back to a safe level.
Fig. 2A-2C show schematic diagrams of an electrochemical cell 200 that uses a porous separator that extends beyond the sealed perimeter of the pouch, thereby releasing gases generated within the pouch 200. Electrochemical cell 200 includes a cathode 210 disposed on a cathode current collector 212, an anode 220 disposed on an anode current collector 222, and a separator 230 disposed therebetween. The assembly of cathode 210, cathode current collector 212, anode 220, anode current collector 222, and separator 230 is substantially contained within a pouch 240, which pouch 240 is sealed along a sealed perimeter 242. The cathode tab 215 is electrically connected to the cathode current collector 212 and extends beyond the pocket 240 for connection with an external circuit. Similarly, an anode tab 225 is electrically connected to the anode current collector 215 and extends beyond the pocket 240 for connection with an external circuit.
In certain embodiments, the separator 230 in the electrochemical cell 200 is porous and at least a portion of the porous separator extends beyond the sealing perimeter 242, as shown in fig. 2C. In this case, the gas within the bag 240 may slowly escape the bag 240 by passing through the porous separator 230, thereby preventing an excess pressure within the bag 240.
The gas release rate (also referred to as gas leakage rate) may depend on several parameters of the separator 230, including the porosity of the separator 230, the pore size of the separator 230, and the thickness of the separator 230.
In certain embodiments, the porosity of the separator 230 may be about 1% to about 90% (e.g., about 1%, about 2%, about 5%, about 10%, about 20%, about 50%, about 60%, about 70%, about 80%, or about 90%, including any values and subranges therebetween).
In certain embodiments, the size of the pores in the porous separator may be about 1 μm to about 200 μm (e.g., about 1 μm, about 2 μm, about 5 μm, about 10 μm, about 20 μm, about 50 μm, about 100 μm, about 150 μm, or about 200 μm, including any values and subranges therebetween).
In certain embodiments, the thickness of the separator 230 may be about 10 μm to about 1mm (e.g., about 10 μm, about 20 μm, about 50 μm, about 100 μm, about 200 μm, about 500 μm, about 750 μm, or about 1mm, including any values and subranges therebetween).
In certain embodiments, the portion of the separator 230 that extends beyond the sealing perimeter 242 can have a length of about 100 μm to about 5mm (e.g., about 100 μm, about 200 μm, about 500 μm, about 1mm, about 2mm, or about 5mm, including any values and subranges therebetween). In certain embodiments, the portion of the separator 230 that extends beyond the sealing perimeter 242 can be about 1% to about 25% (e.g., about 1%, about 2%, about 5%, about 10%, about 15%, about 20%, or about 25%, including any values and subranges therebetween) of the total length of the separator 230.
In certain embodiments, only a portion of the separator 230 is porous. For example, the portion around the sealing perimeter 242 may be porous, while other portions of the separator 230 may be non-porous. The gas within the bag 240 may escape through the porous portion of the separator 230. The partially porous section may reduce possible interference with the normal function of the separator 230.
In certain embodiments, the separator 230 may include a multi-layered structure to create a gas permeable path within the separator. In this case, the gas within the bag 240 may be released from the bag 240 via a gas permeable path.
In certain embodiments, the separator 230 may include a substrate coated with particles or fibers. The particle coating may be breathable. As a result, gas within the bag 240 may be released via the particle coating on the surface of the separator 230. In certain embodiments, the particles may include ceramic particles or/and fibers. In certain embodiments, the ceramic particles may include Al2O3、TiO2、ZrO2AlO (OH) and/or AlF3And the like.
In certain embodiments, the separator 230 may include a substrate coated with other plastic particles and fibers. The plastic coating may be breathable. As a result, gas within the bag 240 may be released via the particle coating on the surface of the separator 230. In certain embodiments, the particles may include Polyimide (PI), polyamide-imide (PAI), Polyetheretherketone (PEEK), Polyethersulfone (PES), polyphenylene sulfide (PPS), and/or phenolic polymers, among others.
In certain embodiments, the particle size may be about 1 μm to about 200 μm (e.g., about 1 μm, about 2 μm, about 5 μm, about 10 μm, about 20 μm, about 50 μm, about 100 μm, about 150 μm, or about 200 μm, including any values and subranges therebetween).
In certain embodiments, the thickness of the particle coating may be about 1 μm to about 200 μm (e.g., about 1 μm, about 2 μm, about 5 μm, about 10 μm, about 20 μm, about 50 μm, about 100 μm, about 150 μm, or about 200 μm, including any values and subranges therebetween).
Fig. 3 shows a front view of an electrochemical cell 300, the electrochemical cell 300 comprising a degassing tail (also referred to as an auxiliary bag) for regulating the gas pressure. Electrochemical cell 300 includes a cathode (not visible from the front view) disposed on a cathode current collector 312, an anode (not visible from the front view) disposed on an anode current collector, and a separator disposed therebetween. The assembly of cathode, cathode current collector 312, anode current collector and separator is substantially contained within a pouch 340, the pouch 340 being sealed along a sealed perimeter 342. The cathode tab 315 is electrically connected to the cathode current collector 312 and extends beyond the pocket 340 for connection with an external circuit. Similarly, anode tab 325 is electrically connected to the anode current collector and extends beyond bag 340 for connection with an external circuit.
The pouch 340 includes a degassing tail 345 in fluid communication with the remainder of the pouch 340 containing the cathode and anode. The gas generated in the cathode may be contained in the degassing tail 345, thereby adjusting the gas pressure within the pouch 340.
In certain embodiments, the degassing tail 345 is in direct communication with the rest of the bag 340. In certain embodiments, the degassing tail 345 may be separated from the rest of the bag 340 by a pressure regulating membrane. Excess gas pressure in the bag 340 can push open the pressure regulating membrane and release the gas into the degassing tail 345. In certain embodiments, the boundary between the degassing tail 345 and the rest of the bag 340 may be partially sealed. For example, a series of sealing points may be applied at the boundary between the degassing tail 345 and the rest of the bag 340. In certain embodiments, the pouch 340 may extend beyond/over the cathode foil tab and the anode foil tab with the degassing tail 345 positioned between or around the cathode tab and the anode tab.
The degassing tail 345 may have various shapes. In certain embodiments, the degassing tail 345 may be rectangular (including square). In certain embodiments, the degassing tail 345 may be circular. In some embodiments, degassing tail 345 may be elliptical. In some embodiments, degassing tail 345 may be polygonal.
In certain embodiments, the volume ratio between the degassing tail 345 and the bag 340 (i.e., the ratio of the degassing tail 345 to the volume of the entire bag 340) may be about 5% to about 50% (e.g., about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50%, including any values and subranges therebetween).
In certain embodiments, the degassing tail 345 may be configured to absorb 20% of the gas produced in the cathode. In certain embodiments, the degassing tail 345 may be configured to absorb 30% of the gas produced in the cathode. In certain embodiments, the degassing tail 345 may be configured to absorb 40% of the gas produced in the cathode. In certain embodiments, the degassing tail 345 may be configured to absorb 50% of the gas produced in the cathode. In certain embodiments, the degassing tail 345 may be configured to absorb 60% of the gas produced in the cathode.
In some embodiments, the degassing tail 345 and the bag 340 may be made of the same material. In some embodiments, the degassing tail 345 and the bag 340 can be made of different materials. For example, bag 340 can be made of a heat resistant material, while degassing tail 345 can be made of a pressure resistant or flexible material.
In certain embodiments, the degassing tail 345 may be disposed at the top of the bag 340 between the two tabs 315 and 325 (as shown in fig. 3). In certain embodiments, the degassing tail 345 may be disposed at the bottom of the bag 340 opposite the two tabs 315 and 325. In certain embodiments, the degassing tail 345 may be disposed on the left and/or right side of the bag 340. In certain embodiments, the degassing tail 345 may be disposed on the front and/or back side of the bag 340. In certain embodiments, the degassing tail 345 may be disposed at the top of the pouch 340 outside of the cathode or anode.
In certain embodiments, electrochemical cell 300 may include only one degassing tail. In certain embodiments, electrochemical cell 300 may include more than one degassing tail. For example, the electrochemical cell 300 may include a first degassing tail (as shown in fig. 3) between the two tabs 315 and 325 and a second degassing tail at the bottom of the pouch 340. In certain embodiments, the electrochemical cell 300 may include: a first degassing tail on the left side of the bag 340 and a second degassing tail on the right side of the bag 340.
Fig. 4A-4C show schematic diagrams of an electrochemical cell 400, the electrochemical cell 400 including a Circuit Interrupting Device (CID) within the pouch to protect the cell 400 from overpressure. Electrochemical cell 400 includes a cathode (not visible from the front view) disposed on a cathode current collector 412, an anode (not visible from the front view) disposed on an anode current collector, and a separator disposed therebetween. The assembly of cathode, cathode current collector 412, anode current collector and separator is substantially contained within a bag 440, the bag 440 being sealed along a sealed perimeter 442. The cathode tab 415 is electrically connected to the cathode current collector 412 and extends beyond the pocket 440 for connection with an external circuit. Similarly, anode tab 425 is electrically connected to the anode current collector and extends beyond bag 440 for connection with an external circuit.
Fig. 4B shows that the cathode tab 415 includes a neck portion 415c between two regular portions: a top portion 415a and a bottom portion 415 b. The neck portion 415c has a reduced width compared to the other portions 415a and 415 b. Fig. 4C shows that the bag 440 is made of two films 440a and 440b that are sealed by heat sealing. The top portion 415a is coupled to the top sealing region 442a of the first film 440a and the bottom portion 415b is coupled to the bottom sealing region 442b of the second film 440 b. As shown in fig. 4C, the top sealing region 442a is located above the neck portion 415C and the bottom sealing region 442b is located below the neck portion 415C. Thus, when gas is generated within the bag 440, the gas can fill any space within the bag until the sealed regions (442a and 442 b). Since the top sealing region 442 is higher than the bottom sealing region 442b, gas may enter the space between the membrane 440a and the neck portion 415 c. However, because this area exceeds the sealing area 442b, gas does not enter the space between the neck portion 415c and the bottom sealing area 442 b. As a result, the gas may exert a force perpendicular to the neck portion 415 c. When the force is above the threshold, the force may break the neck portion 415c and disconnect the electrochemical cell 400 from the external circuit, thereby protecting the cell 400 and the external circuit.
In certain embodiments, the ratio of the width of the neck portion 415c to the top portion 415 a/bottom portion 415b can be about 0.1 to about 0.9 (e.g., about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9, including any values and subranges therebetween).
In certain embodiments, the absolute width of the neck portion 415c can be about 200 μm to about 2mm (e.g., about 200 μm, about 300 μm, about 500 μm, about 750 μm, about 1mm, about 1.2mm, about 1.4mm, about 1.6mm, about 1.8mm, or about 2mm, including any values and subranges therebetween).
In certain embodiments, the length of the neck portion 415c can be about 1mm to about 10mm (e.g., about 1mm, about 2mm, about 3mm, about 4mm, about 5mm, about 6mm, about 7mm, about 8mm, about 9mm, or about 10mm, including any values and subranges therebetween).
In some embodiments, the neck portion 415c and the top portion 415 a/bottom portion 415b can be made of the same material. In some embodiments, the neck portion 415c can be made of a first material and the top portion 415 a/bottom portion 415b can be made of a second material different from the first material. The first material may have less mechanical strength than the second material, thereby promoting fracture of the neck portion 415c under an external force.
In some embodiments, neck portion 415c may include a bridge connecting top portion 415a with bottom portion 415 b. In certain embodiments, neck portion 415c may include a plurality of bridges connecting top portion 415a with bottom portion 415 b.
Fig. 5 shows a side view of an electrochemical cell 500, the electrochemical cell 500 comprising a needle for protecting the cell 500 from overpressure. Electrochemical cell 500 includes a cathode 510 disposed on a cathode current collector 512, an anode 520 disposed on an anode current collector 522, and a separator 530 disposed therebetween. The assembly of cathode 510, cathode current collector 512, anode 520, anode current collector 522, and separator 530 may be configured to be substantially contained in pouch 540. The bag 540 is in turn configured to be substantially contained within the housing 550. A plurality of needles 555 may be disposed on the inner wall of the housing 550 towards the cathode side of the cell 500. When the pouch 540 is inflated due to gas generation within the pouch 540, the needle 555 may open the pouch 540, thereby preventing the battery 500 from being over-pressurized.
In some embodiments, needle 555 may be made of one or more metals. In some embodiments, needle 555 may be made of plastic. In certain embodiments, needle 555 may be made of any other rigid material known in the art.
In some embodiments, needle 555 may include only one needle. In certain embodiments, needle 555 may include multiple needles.
In certain embodiments, the length of needle 555 may be about 0.5mm to about 5mm (e.g., about 0.5mm, about 1mm, about 2mm, about 3mm, about 4mm, or about 5mm, including any values and subranges therebetween).
Fig. 6A-6C illustrate a safety mechanism that employs stratification of electrodes for treating electrochemical cells that exceed a predetermined pressure threshold, according to certain embodiments. In fig. 6A-6C, an electrochemical cell 600 includes a cathode 610 disposed on a cathode current collector 612, an anode 620 disposed on an anode current collector 622, and a separator 630 disposed therebetween. The assembly of cathode 610, cathode current collector 612, anode 620, anode current collector 622, and separator 630 may be configured to be substantially contained in pouch 640.
Fig. 6B shows the pressure within bag 640 increasing beyond a preset pressure threshold. In this case, the pouch 640 may be inflated and the anode 620 may be separated from the separator 630, thereby electrically disconnecting the anode 620 from the cathode 610. In this case, the electrochemical cell 600 may be prevented from further charging. In certain embodiments, the cathode 610 may be configured to separate from the separator 630 when the pressure within the pouch 640 increases beyond a preset pressure threshold, thereby electrically disconnecting the cathode 610 from the anode 620 and preventing further discharge of the electrochemical cell 600. In certain embodiments, at least one of the cathode 610 and the anode 620 may be configured to separate from at least one of the cathode current collector 612 and the anode current collector 622 when the pressure within the pouch 640 increases beyond a preset pressure threshold, thereby electrically disconnecting the cathode 610 from the anode 620 and preventing further charging and/or discharging of the electrochemical cell 600.
Fig. 6C also shows that the internal pressure within bag 640 exceeds the threshold pressure. In fig. 6C, a portion 620a of the anode remains coupled to the anode current collector 622 and separate from the separator 630, while another portion 620b of the anode remains attached to the separator 630. This may also at least partially disconnect the electrochemical cell 600 from an external circuit and protect the electrochemical cell 600. In this mechanism, a first region of laminate 620a may be strategically designed to delaminate from a first surface (e.g., current collector), while a second region of laminate 620b may be configured to delaminate from a second surface (e.g., separator 630), thereby separating cathode 610 and anode 620 from being in electrochemical or electrical contact. In other words, the safety mechanism is designed to physically separate the cathode 610 and the anode 620 such that they are the electrochemical cell 600 or operate as the electrochemical cell 600. The first region of the laminate 620a may include a first portion of the cathode 610, a first portion of the anode 620, or both. The second region of the laminate 620b may include a second portion of the cathode 610, a second portion of the anode 620, or both.
In certain embodiments, a first portion of the cathode 610 or anode 620 may be adhered to the cathode current collector 612 or anode current collector 622 using a first adhesive and may be adhered to the separator 630 using a second adhesive such that the first portion of the cathode 610 or anode 620 is configured to preferentially delaminate from the separator 630. In certain embodiments, the use of the first and second binders may be reversed such that the second portion of the cathode 610 or anode 620 is configured to delaminate, preferably from the cathode current collector 612 or anode current collector 622.
Although the above description discusses the protective measures individually with reference to each drawing, more than one measure may be used for one battery. For example, one cell may include both a vent (as shown in fig. 1A-1C) and a porous separator (as shown in fig. 2A-2C). In another example, a cell may include both a degassing tail (as shown in fig. 3) and a CID (as shown in fig. 4A-4C). Any other combination is also possible.
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