阅读说明：本技术 一种集流体、极片、极片的制备方法及电化学储能装置 (Current collector, pole piece, preparation method of pole piece and electrochemical energy storage device ) 是由 曹恋 黄海宁 刘婵 侯敏 曹辉 于 2019-10-21 设计创作，主要内容包括：本发明公开了一种集流体、极片、极片的制备方法及电化学储能装置,该集流体为多孔金属薄板,厚度为0.5～20mm,孔径为0.05～2mm,孔隙率60％～99.5％；体积密度0.1～1.0g/cm<Sup>3</Sup>。本发明提供的新型集流体,可增加电极厚度到毫米级别,以减少隔膜层数,且集流体充当骨架,提高了活性材料填充率,降低了集流体“无效厚度”,从而实现体积能量密度提高,且不恶化电池内阻；与此同时,该新型集流体在针刺等情况下能有效避免集流体大毛刺的产生,且小尺寸毛刺与集流体本体接触面积极小,局部短接过程中可迅速熔断,避免持续发热造成温升,将电池失控限制在局部点范围。(The invention discloses a current collector, a pole piece, a preparation method of the pole piece and an electrochemical energy storage device, wherein the current collector is a porous metal sheet, the thickness of the current collector is 0.5-20 mm, the pore diameter of the current collector is 0.05-2 mm, and the porosity of the current collector is 60-99.5%; the bulk density is 0.1 to 1.0g/cm 3 . The novel current collector provided by the invention can increase the thickness of an electrode to a millimeter level so as to reduce the number of layers of the diaphragm, and the current collector serves as a framework, so that the filling rate of an active material is improved, and the invalid thickness of the current collector is reduced, thereby realizing the improvement of volume energy density without deteriorating the internal resistance of a battery; meanwhile, the novel current collector can effectively avoid the generation of large burrs of the current collector under the conditions of needling and the like, and the small-size burrs and the current collectorThe contact area of the body is extremely small, the body can be rapidly fused in the process of local short circuit, the temperature rise caused by continuous heating is avoided, and the battery is out of control and limited in the range of local points.)

1. The current collector is characterized in that the current collector is a porous metal sheet, the thickness of the current collector is 0.5-20 mm, the pore diameter of the current collector is 0.05-2 mm, and the porosity of the current collector is 60% -99.5%; the bulk density is 0.1 to 1.0g/cm³。

2. The current collector of claim 1, wherein the current collector is a metal foam and has a porosity greater than 90%.

3. The current collector of claim 1, wherein the current collector has a thickness of 1 to 3mm, and wherein the metal comprises copper or aluminum.

4. A pole piece, comprising: a current collector as claimed in any one of claims 1 to 3, and an electrode active material filled in the current collector; wherein the electrode active material comprises a positive electrode active material and a negative electrode active material.

5. The pole piece of claim 4, wherein the pole piece comprises a positive pole piece and a negative pole piece, wherein a current collector forming the positive pole piece is foamed 1-series aluminum, and the positive active material is ternary NCM; the current collector of the negative plate is made of foam copper, and the negative active material is artificial graphite.

6. The pole piece of claim 4, further comprising: and the conductive agent and the adhesive are filled in the current collector.

7. A method for preparing a pole piece according to claim 6, comprising:

step 1, dry-mixing an electrode active material, a conductive agent and a binder completely or adding a certain solvent for wet mixing;

step 2, filling the mixed powder or slurry into the current collector;

and 3, rolling until the pole piece needs to be compacted to form a pole piece with the macroscopic size of 0.1-1 mm, wherein the porosity of the pole piece can be 20-60%.

8. The preparation method of the pole piece according to claim 7, wherein in the step 1, the mass percentage of the electrode active material is 80-99%, the mass percentage of the conductive agent is 0.5-10%, and the mass percentage of the binder is 0.5-10%.

9. An electrochemical energy storage device comprises a lithium ion dry battery cell, and is characterized in that the dry battery cell comprises the positive electrode plate and the negative electrode plate of claim 5, and the thicknesses of the positive electrode plate and the negative electrode plate are both 0.1-1 mm.

10. The electrochemical energy storage device of claim 9, wherein said dry cell further comprises a separator, positive and negative pole pieces being spaced apart by said separator, respectively, said dry cell being formed by lamination.

Technical Field

The utility model relates to a lithium ion battery field relates to a solve novel mass flow body and electrochemistry energy memory of short circuit risk in the battery, concretely relates to mass flow body, pole piece's preparation method and electrochemistry energy memory, and this novel mass flow body has obvious improvement effect to promoting lithium ion battery energy density and compromise the security performance.

Background

With the development of automobile intellectualization and national requirements for energy conservation and emission reduction, new energy automobiles are steadily developed in recent years. Compared with the traditional fuel vehicle, the new energy vehicle with the power output system provided by the lithium battery still has obvious disadvantages in the aspect of endurance mileage, and the development of the new energy vehicle is also restricted.

Therefore, increasing the energy density becomes an important development direction of lithium batteries. However, high energy density tends to run counter to high safety, which also means high short circuit energy, with short circuit conditions producing more heat faster and more chance of thermal runaway. Particularly, high nickel materials such as NCM622 and NCM811 are hot spots for increasing the energy density (10%), but the thermal stability of these materials in the lithium-removed state deteriorates with the increase of the nickel content, which is manifested by a decrease in the oxygen loss temperature and an increase in the heat generation amount.

When the battery is under a needling condition, the traditional positive current collector is in short circuit with a negative active material, the contact resistance is small, the current is large, and the temperature rise after short circuit reaches 300-500 ℃, so that a series of side reactions are triggered to cause thermal runaway of the battery. The conventional methods such as ceramic coating diaphragm and coating current collector can not solve the thermal runaway problem in the needling process.

In addition, the conventional idea of increasing the energy density in the lithium ion battery manufacturers is to increase the electrode thickness to reduce the number of electrode layers, thereby reducing the number of separator layers, or to reduce the current collector to increase the coating thickness. For the former, the traditional electrode is increased along with the thickness, the electrolyte infiltration effect is greatly reduced, the ionic conductivity is obviously deteriorated, the polarization and the internal resistance are increased, for the latter, the current collector thinning is limited by the manufacturing capability of a current collector supplier, the processing performance of the thinned current collector is obviously deteriorated, and in addition, the two methods can not break through the limit of the electrode thickness micron order, the improvement on the energy density is limited by about 2% -5%;

disclosure of Invention

In view of the problems mentioned in the background art, the present application aims to provide a novel current collector and an electrochemical energy storage device capable of increasing energy density and significantly improving the risk of internal short circuit. This novel mass flow body can promote lithium ion battery's volume energy density about 10%, improvement lithium cell's that simultaneously can show safety characteristic, especially acupuncture, the thermal runaway that causes under the internal short circuit condition such as extrusion.

In order to achieve the purpose, the invention provides a current collector, which is a porous metal sheet, the thickness of the current collector is 0.5-20 mm, the pore diameter of the current collector is 0.05-2 mm, and the porosity of the current collector is 60% -99.5%; the bulk density is 0.1 to 1.0g/cm³。

Preferably, the current collector is a foam metal, and the porosity is greater than 90%.

Preferably, the metal comprises copper or aluminum.

The invention also provides a pole piece, comprising: the current collector and an electrode active material filled in the current collector; wherein the electrode active material comprises a positive electrode active material and a negative electrode active material.

Preferably, the pole piece comprises a positive pole piece and a negative pole piece, wherein a current collector forming the positive pole piece is foamed 1-series aluminum, and a positive active material is ternary NCM; the current collector of the negative plate is made of foam copper, and the negative active material is artificial graphite.

Preferably, the pole piece further comprises: and the conductive agent and the adhesive are filled in the current collector.

The invention also provides a preparation method of the pole piece, which comprises the following steps:

step 1, dry-mixing an electrode active material, a conductive agent and a binder completely or adding a certain solvent for wet mixing;

step 2, filling the mixed powder or slurry into the current collector;

and 3, rolling until the pole piece needs to be compacted to form a pole piece with the macroscopic size of 0.1-1 mm, wherein the porosity of the pole piece can be 20-60%. The porosity of the pole piece is convenient for the infiltration of electrolyte and is one of the characteristics of a processed semi-finished product.

Preferably, in step 1, the mass percentage of the electrode active material is 80-99%, the mass percentage of the conductive agent is 0.5-10%, and the mass percentage of the binder is 0.5-10%.

The invention also provides an electrochemical energy storage device which comprises a lithium ion dry battery cell, wherein the dry battery cell comprises the positive pole piece and the negative pole piece.

Preferably, the dry electric core further comprises a diaphragm, the positive and negative pole pieces are respectively spaced by the diaphragm, and the dry electric core is formed by lamination.

Different from the conventional 5-20 um metal current collector, the novel current collector provided by the invention is a foam metal sheet, active substances, conductive agents, binding agents and other materials are filled in the foam metal sheet to prepare an electrode plate, and the electrode plate can be processed to a millimeter level by designing the thickness and the aperture size of the foam metal sheet and the compaction of the electrode plate, so that the number of layers of a diaphragm is reduced, the current collector serves as a framework, the filling rate of the active materials is improved, the 'invalid thickness' of the current collector is reduced, and the volume energy density is improved; meanwhile, the foam metal sheet can be used as a metal support, the porosity of the pole piece is maintained, the problem that the electrolyte cannot be fully infiltrated after the pole piece is thickened to a millimeter level is solved, and the negative effects of polarization and internal resistance increase are avoided while the energy density is improved. More importantly, the porous current collector can avoid the generation of large-size burrs under the conditions of needling and the like, and when small-size burrs are in short-circuit contact with a negative electrode active material, the contact area of the burrs and the current collector body is extremely small, so that the current collector can be rapidly fused at the moment of heat release, the phenomenon that the temperature rise is caused by continuous heating is avoided, and the battery is controlled in a local point range.

The invention has the beneficial effects that:

1) the novel current collector provided by the invention can increase the thickness of the electrode to a millimeter level, thereby reducing the number of layers of the diaphragm and improving the energy density;

2) the current collector serves as a framework, so that the filling rate of an active material is improved, and the 'invalid thickness' of the current collector is reduced, so that the volume energy density is improved, and the internal resistance of the battery is not deteriorated;

3) this novel mass flow body can effectively avoid the production of the big burr of mass flow body under the circumstances such as acupuncture, and small-size burr is minimum with mass flow body area of contact, can fuse rapidly in the local short circuit in-process, avoids continuously generating heat and causes the temperature rise, with the battery restriction in local point scope of out of control.

Detailed Description

The following are examples of the novel porous electrode for lithium batteries of the present invention. The following detailed description of specific embodiments of the present invention is provided as part of the present specification for the purpose of better illustrating the invention and is not intended to limit the scope of the invention. Those skilled in the art can make modifications or adjustments similar to the present invention based on the above description of the present invention, and all such modifications or adjustments fall within the scope of the present invention. In addition, the specific process ratios and process parameters in the following examples need to be adjusted to appropriate parameters according to actual conditions.