阅读说明：本技术 可再充电金属卤化物电池 (Rechargeable metal halide battery ) 是由 金暲祐 罗英惠 G·布雷耶塔 于 2020-03-02 设计创作，主要内容包括：一种电池,包括：阳极；电解质,包括：氧化气体；包含金属卤化物的活性阴极材料；以及包含杂环化合物的溶剂；以及接触所述活性阴极材料的集电器。(A battery, comprising: an anode; an electrolyte, comprising: an oxidizing gas; an active cathode material comprising a metal halide; and a solvent comprising a heterocyclic compound; and a current collector contacting the active cathode material.)

1. A battery, comprising:

an anode;

an electrolyte, wherein the electrolyte comprises:

an oxidizing gas;

an active cathode material comprising a metal halide; and

a solvent comprising a heterocyclic compound; and

a current collector contacting the active cathode material.

2. The battery of claim 1, wherein the solvent in the electrolyte comprises a heterocyclic compound selected from the group consisting of cyclic ethers, cyclic esters, and mixtures and combinations thereof.

3. The battery of claim 1, wherein the current collector comprises an electrically conductive porous material.

4. The battery of claim 1, further comprising a separator between the anode and the current collector.

5. The battery of claim 1, wherein the anode comprises at least one of Li, Mg, and Na.

6. The battery of claim 1, wherein the oxidizing gas is selected from the group consisting of oxygen, air, nitric oxide, nitrogen dioxide, and mixtures and combinations thereof.

7. The battery of claim 1, wherein the solvent in the electrolyte is selected from the group consisting of tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, oxathiolane, succinimide, oxazolidinone, gamma-butyrolactone, gamma-caprolactone, epsilon-caprolactone, gamma-valerolactone, pyrrolidine, imidazolidine, sulfolane, thiacyclohexane, and mixtures and combinations thereof.

8. The battery of claim 1, wherein the metal halide comprises an electrolyte salt that dissociates in the solvent into a corresponding halide ion and a corresponding metal ion, and wherein the halide ion comprises an ion of at least one of I, Br, Cl, and F, and the metal ion comprises an ion of at least one of Li, Mg, and Na.

9. The battery of claim 1, further comprising an additional salt that dissociates into a corresponding metal ion and a corresponding counter anion, wherein the metal ion is selected from the group consisting of Li, Mg, and Na, and mixtures and compositions thereof, and the anion is selected from the group consisting of nitrate (NO 3)^-) Hexafluorophosphate (PF 6)^-) Tetrafluoroborate (BF 4)^-) Bis (oxalato) borate (BOB)^-) And difluorooxalato borate salt (DFOB)^-) Triflate (TF)^-) Triflimide (TFSI)^-) And mixtures and compositions thereof.

10. The battery of claim 1, wherein the solvent further comprises an organic solvent selected from the group consisting of ethers, glymes, carbonates, nitriles, amides, amines, organosulfur solvents, organophosphorous solvents, silicone solvents, fluorinated solvents, and mixtures and combinations thereof.

11. The battery of claim 1, further comprising a dedicated cathode material in addition to the active cathode material comprising the metal halide, wherein the dedicated cathode material provides a conductive path to an external circuit to which the battery is connected.

12. A battery, comprising:

(a) an anode that absorbs metal ions from an electrolyte during charging and releases these ions into the electrolyte during discharging, the electrolyte comprising:

(i) a solvent comprising a heterocyclic compound, and

(ii) a dissolved halide, wherein the halide functions as the cathode of the battery;

(b) a Solid Electrolyte Interphase (SEI) layer in contact with the anode, the SEI layer comprising an oxide of the metal ion; and

(c) a current collector comprising an electrically conductive porous material, wherein the current collector contacts the dissolved halide.

13. The battery of claim 12, wherein the electrolyte is non-aqueous.

14. The battery of claim 12, wherein the halide is selected from the group consisting of I-, Br-, Cl-, F-, and mixtures and combinations thereof.

15. The battery of claim 12, wherein the electrolyte comprises a salt that releases the metal ions.

16. The battery of claim 12, wherein the anode comprises an intercalation host material capable of absorbing metal ions.

17. The battery of claim 12, further comprising a second cathode in addition to the metal halide used as the active cathode material.

18. A method of forming a battery comprising:

dissolving a metal halide in a solvent comprising a heterocyclic compound, thereby forming a solution;

soaking a separator with the solution;

stacking an anode, the separator soaked with the solution, and a current collector, wherein the stacking comprises placing the separator soaked with the solution between the anode and the current collector; and

introducing an oxidizing gas into the stacked anodes, the separator soaked with the solution, and the current collector to form the battery, wherein the battery comprises:

an anode, a cathode, a anode and a cathode,

an electrolyte, the electrolyte comprising:

an oxidizing gas;

an active cathode material comprising a metal halide; and

a solvent comprising a heterocyclic compound; and

a current collector contacting the cathode material.

Background

Rechargeable batteries are used as power sources in a wide range of applications, such as, for example, industrial devices, medical devices, electronic devices, electric vehicles, and grid energy storage systems. Battery technology is constantly evolving to enable higher energy densities and higher efficiencies, allowing batteries to be used as power sources for additional applications.

The need for high specific capacity and high specific energy has led to the study of different metal element batteries. Lithium intercalation cathode materials such as lithium nickel manganese cobalt oxide (NMC), lithium Nickel Cobalt Alumina (NCA), Lithium Cobalt Oxide (LCO), lithium iron phosphate (LFP), and the like have relatively low energy densities and can be expensive. To identify new and more efficient cathode materials, conversion cathode materials such as sulfur, oxygen, air, and others have been investigated.

Batteries made with lithium-oxygen, lithium-air, and mixtures of lithium and other oxygen-containing gases have excellent performance due, at least in part, to the low atomic number, low density, and high reducing power of elemental lithium. Furthermore, lithium-oxygen batteries can potentially have a theoretical specific energy three to five times greater than conventional lithium ion batteries.

Lithium metal has a high energy storage capacity and has been used as a primary battery anode material. In some cases, lithium metal anodes can form dendrites, which can cause short circuits during battery operation. It has also proven difficult to find reasonably inexpensive cathode materials that can accommodate the large quantities of lithium ions and electrons extracted from lithium metal anodes.

Disclosure of Invention

Some batteries that include sulfur, oxygen, air, or other active cathode materials have poor cycling capability, low power density, or both. For example, such batteries may be relatively unstable and/or undergo parasitic reactions, which may lead to electrochemically irreversible carbonate byproducts that reduce the cycling capability and/or power density of the battery, e.g., due to electrolyte decomposition or carbon surface oxidation.

In general, the invention relates to a battery having a solvent including an oxidizing gas, a metal halide, and a heterocyclic compound. In various embodiments of the present invention, the battery has one or more of a relatively fast charge rate, high energy efficiency, high power density, and good cycling capability. Additionally, in some embodiments of the invention, the electrolyte may be more cost effective and potentially less hazardous than some other battery electrolytes. The electrolyte can provide high power density in metal-based batteries by forming small and dense nuclei that also have relatively consistent dimensions, which can strongly and naturally inhibit unwanted dendritic growth on the anode. In addition, the electrolyte does not include heavy metals such as cobalt or nickel, and thus it is expected that the overall cost of the battery can be reduced.

In one aspect, the present disclosure relates to a battery comprising: an anode; an electrolyte, the electrolyte comprising: an oxidizing gas; an active cathode material comprising a metal halide; and a solvent comprising a heterocyclic compound; and a current collector contacting the active cathode material.

In another aspect, the present invention is directed to a battery comprising: (a) an anode that absorbs metal ions from an electrolyte during charging and releases the ions to the electrolyte during discharging, the electrolyte comprising: (i) a solvent comprising a heterocyclic compound, and (ii) a dissolved halide, wherein the halide functions as the cathode of the battery; (b) a Solid Electrolyte Interphase (SEI) layer in contact with the anode, the SEI layer comprising an oxide of the metal; and (c) a current collector comprising an electrically conductive porous material, wherein the current collector contacts the dissolved halide.

In another aspect, the invention relates to a method of forming a battery comprising: dissolving a metal halide in a solvent comprising a heterocyclic compound to form a solution; soaking a separator with the solution; stacking an anode, the separator soaked with the solution, and a current collector, wherein the stacking comprises placing the separator soaked with the solution between the anode and the current collector; and introducing an oxidizing gas into the stacked anodes, the separator soaked with the solution, and the current collector to form the battery, wherein the battery comprises: an anode, an electrolyte, the electrolyte comprising: an oxidizing gas; an active cathode material comprising a metal halide; and a solvent comprising a heterocyclic compound; and a current collector contacting the active cathode material.

The details of one or more examples of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is a conceptual diagram illustrating an exemplary battery including an anode, an electrolyte, a current collector, and an optional separator.

Fig. 2 is a conceptual diagram illustrating the example battery of fig. 1 within an enclosed cell.

Fig. 3 is a flow diagram illustrating an example technique for manufacturing a battery.

Fig. 4A-4B are graphs of discharge and charge galvanostatic cycling behavior and area-specific discharge capacity versus cycle number of the battery for the first cycle using 1M LiI-GBL in the presence of oxygen as described in example 2. At 5mA/cm²Operating the cell at a current density of.

Fig. 5A-5B are graphs of discharge and charge galvanostatic cycling behavior and area specific discharge capacity versus cycle number of the cell for the first cycle using 1M LiI-ECL in the presence of oxygen as described in example 3. At 5mA/cm²Operating the cell at a current density of.

Fig. 6A-6B are graphs of discharge and charge galvanostatic cycling behavior and area specific discharge capacity versus cycle number of the cell for the first cycle using 1M LiI-THF electrolyte in the presence of oxygen as described in example 4. At 5mA/cm²Operating the cell at a current density of.

Fig. 7 is a graph of discharge and charge galvanostatic cycling behavior for the first cycle in the absence of oxygen using 1M LiI-GBL in the cell of comparative example 1. At 5mA/cm²Operating the cell at a current density of.

Fig. 8 is a graph of discharge and charge galvanostatic cycling behavior for the 50 th cycle using 1M LiI-TEGDME electrolyte in the presence of oxygen in the cell of comparative example 2. At 5mA/cm²Operating the cell at a current density of.

Like reference symbols in the various drawings indicate like elements.

Detailed Description

Fig. 1 is a conceptual diagram illustrating an exemplary battery 10 including a negative electrode 12, an electrolyte 14, a current collector 16, and an optional separator 18. The cell 10 operates by a reduction-oxidation (redox) reaction and utilizes the different oxidation states and redox reactions of one or more components or elements for charging and discharging.

Anode 12 can be made of any metal, and suitable examples include, but are not limited to, lithium, magnesium, sodium, and mixtures and combinations thereof. In some examples, anode 12 consists essentially of elemental lithium, magnesium, or sodium, or lithium, or magnesium, or sodium alloyed with one or more additional elements. In some embodiments, anode 12 is composed of elemental lithium, magnesium, sodium, or lithium.

Anode 12 may absorb metal ions from electrolyte 14 during charging and release metal ions to electrolyte 14 during discharging. In some embodiments, anode 12 may be an intercalation host material capable of absorbing metal ions. In some examples, a Solid Electrolyte Interphase (SEI) layer may be in contact with the anode 12. For example, the SEI layer may include an oxide of a metal from the electrolyte 14.

Electrolyte 14 may be aqueous or non-aqueous and includes a solvent containing a heterocyclic compound, a metal halide, and an oxidizing gas. In the present application, the term heterocyclic compound refers to an aromatic or non-aromatic cyclic compound having at least two different element atoms as ring members. As used herein, a cyclic compound (ring compound) refers to a compound in which one or more atom series in the compound are linked to form a ring. In various embodiments, suitable cyclic compounds for electrolyte 14 include 5-membered rings such as pyrrolidine, oxolane, thiolane, pyrrole, furan, and thiophene; 6-membered rings such as piperidine, dioxane, thiane, pyridine, pyran and thiopyran; and 7-membered rings such as azepane, oxepane, thiepane, azepane, oxepane, and thiene. Examples of suitable heterocyclic compounds include, but are not limited to, tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, oxathiolane, succinimide, oxazolidinone, gamma-butyrolactone, gamma-caprolactone, epsilon-caprolactone, gamma-valerolactone, pyrrolidine, imidazolidine, sulfolane, thiacyclohexane, and mixtures and combinations thereof. In some embodiments, suitable heterocyclic compounds include, but are not limited to, cyclic ethers, cyclic esters, and mixtures and combinations thereof.

In some examples, electrolyte 14 may include one or more additional solvents. In some embodiments, the one or more additional solvents may be selected from non-aqueous organic solvents, such as ethers, glymes, carbonates, nitriles, amides, amines, organosulfur solvents, organophosphorus solvents, silicone solvents, fluorinated solvents, Adiponitrile (ADN), Propylene Carbonate (PC), Dimethoxyethane (DME), and mixtures and combinations thereof. In some examples, electrolyte 14 includes equal portions of solvent (including heterocyclic compounds) and one or more additional solvents. In some examples, one or more additional solvents in electrolyte 14 may be selected to further improve the electrochemical performance of battery 10, e.g., by enhancing rechargeability, cyclability, etc.

Electrolyte 14 includes an oxidizing gas. In some examples, electrolyte 14 may be in the presence of an oxidizing gas, and the phrase "comprising an oxidizing gas" is intended to include such a configuration. In some embodiments, the oxidizing gas may be dissolved in a solvent comprising the heterocyclic compound of the electrolyte 14. In some examples, which are not intended to be limiting, the oxidizing gas includes at least one of oxygen, air, nitric oxide, or nitrogen dioxide. The oxidizing gas helps to induce the redox reaction of the cell 10 as described above and helps to achieve a highly reversible redox reaction, which may help to enhance the electrochemical performance of the cell 10. The oxidizing gas may help induce such redox reactions, but is not consumed or released during use of the cell 10 (e.g., the oxidizing gas does not participate in the redox reactions of the cell 10). In some examples, the electrolyte comprising the metal halide and the solvent comprising the heterocyclic compound but not the oxidizing gas may exhibit little or no rechargeability.

The electrolyte 14 also includes a metal halide (e.g., MX, where M is a metal element and X is a halogen element). In some examples, the metal halide includes an electrolyte salt that dissociates into a corresponding halide ion and a corresponding metal ion. For example, a metal halide can be dissolved in a solvent that includes a heterocyclic compound and disassociate into the corresponding metal and halide ions. In some examples, the halide ion can include an ion of at least one of I, Br, Cl, or F (e.g., X can be I, Br, Cl, or F), and the metal ion can include an ion of at least one of Li, Mg, or Na (e.g., M can be Li, Mg, or Na). In other examples, the metal halide may include elements other than I, Br, Cl, F, Li, Mg, and/or Na. The metal halide may provide ionic conductivity to the electrolyte 14.

In some embodiments, electrolyte 14 includes an optional additional salt that dissociates into the corresponding metal ion and the corresponding counter anion. In some examples, which are not intended to be limiting, the metal ion comprises at least one of Li, Mg, and Na, and the counter anion comprises Nitrate (NO)₃ ^-) Hexafluorophosphate radical (PF)₆ ^-) Tetrafluoroborate (BF)₄ ^-) Bis (oxalato) borate (BOB)^-) Difluoro oxalato borate (DFOB)^-) Triflate (TF)^-) And Trifluorosulfonimide (TFSI)^-) One or more of (a).

Additionally or alternatively, the metal halide of the electrolyte 14 may serve as the active cathode material. For example, the metal halide may receive, store, and release metal ions during charging and discharging of the battery 10. In this manner, the battery 10 may not include a dedicated cathode material. Rather, the battery 10 may include an active cathode material of metal halide of the electrolyte 14 and a current collector 16. Further, battery 10 may be less expensive to manufacture, lighter in weight, have a higher power density, or a combination thereof. In some cases, the high power density of the electrolyte including the metal halide acting as an active cathode material may enable battery 10 to charge significantly faster than some other batteries that do not include the electrolyte described herein. In some examples, an electrolyte comprising a solvent (comprising a heterocyclic compound) and an oxidizing gas (but not comprising a metal halide) may have reduced electrochemical properties (e.g., reversibility, rechargeability, and/or cyclability), produce irreversible carbonate byproducts, have reduced power density, or a combination thereof, as compared to electrolyte 14.

Current collector 16 may include a material having suitable electrical conductivity that collects electrons generated by the redox reaction during discharge of battery 10 and provides a conductive path to an external circuit to which battery 10 is connected. Similarly, during recharging of battery 10, current collector 16 provides an electrical path between an external voltage source and electrolyte 14 to supply a voltage for another redox reaction to charge battery 10. In some examples, current collector 16 may include conductive powders, such as metal and/or carbon powders, woven or non-woven metal fibers, metal foams, woven or non-woven carbon fibers, and the like. Additionally or alternatively, the current collector 16 may include stainless steel mesh, aluminum (Al) mesh, nickel (Ni) foam, and/or carbon paper. For example, in one embodiment, current collector 16 may comprise a stainless steel mesh with carbon nanoparticles deposited thereon. As yet another example, the current collector may be a conductive porous material.

In other examples, battery 10 may include a dedicated cathode material in addition to the metal halide used as the active cathode material and current collector 16. For example, the battery 10 may include a cathode that provides a conductive path to an external circuit to which the battery 10 is connected. In some cases, battery 10 may include a cathode that may be used in a lithium ion battery. For example, the cathode can include lithium cobalt oxide (LCO, e.g., LiCoO)₂) Nickel cobalt aluminum (NCA, e.g., LiNi)_xCo_yAl_zO₂、LiNi_0.8Co0.15Al_0.05O₂) Lithium-ion manganese oxide (LMO, e.g. LiMn)₂O₄) Lithium nickel manganese cobalt oxide (NMC, e.g. LiNiMnCoO)₂) Nickel cobalt manganese (NCM, e.g. LiNi)_xCo_yMn_zO₂、LiNi_0.33Co_0.33Mn_0.33O₂) Or lithium iron phosphate (LFP, e.g., LiFePO)₄) At least one of (1). In other examples, battery 10 may include different or additional cathode materials.

In some examples, battery 10 includes an optional separator 18. The separator 18 may force electrons through an external circuit to which the battery 10 is connected such that the electrons do not travel through the battery 10 (e.g., through the electrolyte 14 of the battery 10), while still allowing metal ions to flow through the battery 10 during charging and discharging. In some examples, separator 18 may be soaked with electrolyte 14, within electrolyte 14, surrounded by electrolyte 14, or the like. Separator 18 may include a non-conductive material to prevent electrons from moving through battery 10 such that the electrons move through an external circuit. For example, the separator 18 may include glass, non-woven fibers, polymeric membranes, rubber, and the like.

In some examples, the battery 10 has a closed or substantially closed volume. For example, anode 12, electrolyte 14, current collector 16, and separator 18 may be located within a closed or substantially closed cell or other housing. In this manner, the oxidizing gases of electrolyte 14 are retained within cell 10 such that cell 10 has a relatively fast charge rate, high energy efficiency, high power density, high reversibility, high cycling capability, or a combination thereof, as described herein.

The battery 10 can withstand many charge and discharge cycles (e.g., exhibit good rechargeability), even at relatively high charge densities. In some examples, the battery 10 can be at greater than or equal to about 1mA/cm²About 5mA/cm²About 10mA/cm²Or about 20mA/cm²At a current density of at least 100 cycles of charging and discharging. As one example, the battery 10 may be capable of operating at greater than or equal to about 1mA/cm²About 5mA/cm²About 10mA/cm²Or about 20mA/cm²At least 1000 charge and discharge cycles are completed at the current density of (a).

Additionally or alternatively, battery 10 may exhibit relatively high energy efficiency. For example, at greater than or equal to about 1mA/cm²About 5mA/cm²About 10mA/cm²Or about 20mA/cm²The battery 10 may exhibit an energy efficiency of greater than or equal to 90%. In some examples, the concentration is greater than or equal to about 1mA/cm²About 5mA/cm²About 10mA/cm²Or about 20mA/cm²The battery 10 may exhibit an energy efficiency of greater than or equal to 99% at the current density of (a).

Fig. 2 is a conceptual diagram illustrating the example battery 10 of fig. 1 within a closed battery system 20. The enclosed battery system 20 may include a battery housing the battery 10 during operation of the battery 10, a battery used to manufacture the battery 10, or both. For example, the closed battery system 20 may include a battery available under the trade name SWAGELOK from SWAGELOK of Solon, ohio, and may be used to manufacture the battery 10. In some examples, the closed battery system 20 may include an inlet duct 22 and/or an outlet duct 24. Inlet and outlet tubes 22 and 24 may be used to introduce and remove air or other gases, such as oxidizing gases of electrolyte 14, into and out of the closed cell.

Fig. 3 is a flow chart illustrating an example technique for manufacturing the battery 10 of fig. 1. The technique of fig. 3 will be described with respect to the closed cell system 20 of fig. 2. However, in other examples, the technique of fig. 3 may be used in systems other than the closed cell system 20 of fig. 2. Further, while the technique of fig. 3 is described with respect to a closed battery system, in some examples, fig. 3 may be used with batteries that are not fully closed (e.g., at least partially open).

The technique of fig. 3 includes dissolving a metal halide in a solvent containing a heterocyclic compound to form a solution (30). To dissolve the metal halide in the solvent containing the heterocyclic compound, the metal halide may be added to the solvent containing the heterocyclic compound and stirred gently, for example, gently stirred overnight. In some examples, the solution of the metal halide dissolved in the solvent comprising the heterocyclic compound may have a concentration between about 0.1M and about 20M, between about 0.5M and about 10M, or between about 1M and about 5M.

In some examples, the metal halide may be dried prior to being dissolved in the solvent comprising the heterocyclic compound. The drying temperature and/or drying time may be selected based on the metal halide to be used in the electrolyte 14, and in some non-limiting examples, the metal halide may be dried at about 120 ℃ for greater than 12 hours in an argon-filled glove box on a hot plate.

In addition, or as an alternative to drying the metal halide, in some examples, the solvent including the heterocyclic compound may also be dried prior to dissolving the metal halide therein. For example, a solvent containing a heterocyclic compound may be stored overnight with molecular sieves.

The technique of fig. 3 further includes soaking the optional separator 18 with a solution (32). Soaking the separator 18 with the solution may include immersing the separator 18 in the solution, applying the solution to the separator 18, or any other method of soaking the separator 18 with the solution. In some examples, soaking the separator 18 with the solution may include soaking at about 1 μ L/cm²To about 500. mu.L/cm²About 10. mu.L/cm²To about 250. mu.L/cm²Or about 50. mu.L/cm²To about 100. mu.L/cm²The solution in the range of (1) soaks the separator 18.

The technique of fig. 3 additionally includes stacking the anode 12, the optional separator 18 soaked with the solution, and the current collector 16 within a closed cell system 20(34), e.g., as shown in fig. 2. In some examples, stacking may include placing a separator 18 between the anode 12 and the current collector 16. In some examples, one or more of the anode 12, the separator 18 soaked with the solution, or the current collector 16 may be stacked prior to soaking the separator 18 with the solution. For example, the separator 18 may be stacked on the anode 12 and then soaked with the solution. In some cases, the closed cell system 20 may be at least partially open during the stacking process, and after stacking the anode 12, the solution soaked separator 18, and the current collector 16, the closed cell system 20 may be closed or substantially closed to form a closed or substantially closed volume around the anode 12, the solution soaked separator 18, and the current collector 16.

In other examples, battery 10 may not include separator 18. In such examples, electrolyte 14 may be introduced to cell 10 in different ways. For example, the battery 10 may include the electrolyte 14 between the anode 12 and the current collector 16 without the separator 18. Electrolyte 14 may be introduced into battery 10 in any applicable manner such that electrolyte 14 may function as described herein. In this manner, the technique of fig. 3 may include stacking anode 12 and current collector 16 within a closed battery system 20.

The technique of fig. 3 also includes introducing an oxidizing gas into closed cell system 20 to produce electrolyte 14 and produce cell 10 (36). In some examples, introducing an oxidizing gas into the closed cell system 20 to produce the electrolyte 14 and fabricating the cell 10 includes introducing the oxidizing gas into the closed cell 20 via the inlet tube 24. In some examples, the closed cell system 20 may include or be in the presence of an inert gas (e.g., argon) prior to introducing the oxidizing gas into the closed cell system 20. In some such examples, the introduction of the oxidizing gas may purge and completely replace the inert gas within the enclosed basin system 20 with the oxidizing gas. For example, oxidizing gas may be introduced into the closed cell 20 via an inlet pipe 24, and inert gas may be purged through an outlet pipe 26. In some examples, the concentration of the oxidizing gas in the enclosed basin system 20 may be between about 5 weight percent (wt) and about 100 wt%, between about 50 wt% and about 100 wt%, or between about 80 wt% and about 100 wt% of the total amount of gas within the enclosed basin system 20 (e.g., the total amount of oxidizing gas and inert gas within the enclosed basin system 20).

The invention will now be described with respect to the following non-limiting examples.

Examples of the invention

Example 1: preparation of electrolyte and battery assembly

Lithium iodide (LiI) was placed in a vial and argon filled glove box (< 0.1ppm H) at 120 deg.C₂O，O₂) Dried on an inner hot plate for 1 hour. Gamma-butyrolactone (GBL), epsilon-caprolactone (ECL), and Tetrahydrofuran (THF) were selected as suitable examples of heterocyclic compounds for battery electrolytes and molecular sieves were usedPurification was carried out overnight. 1M of dried LiI powder was added, dissolved in the solution comprising the selected heterocyclic compound, and gently stirred overnight.

The separator on top of the lithium metal anode was soaked with 1M LiI in a heterocyclic compound electrolyte solution and a carbon coated current collector was placed on the other side of the separator. Thus, a separator wetted by the electrolyte solution is placed between and in contact with both the anode and the cathode. Cell assembly was performed in an argon filled glove box.

All battery assemblies were placed in a battery available under the trade name SWAGELOK from SWAGELOK corporation of soyron, ohio, which includes both inlet and outlet tubes for oxygen flow. Oxygen was then introduced through the inlet tube, purging and completely replacing the argon within the cell.

As shown below, the batteries using electrolytes including GBL exhibit higher energy efficiency, while the use of ECL provides longer cycle life. Mixtures of these solvents will likely provide the strength of each solvent and become ideal electrolyte systems for rechargeable metal halide cells.

For the comparative example, 1M LiI-GBL in an oxygen-free environment and 1M LiI in Tetraglyme (TEGDME) in an oxygen-containing environment were tested in the same battery configuration.

Example 2: rechargeable lithium iodide cell with GBL electrolyte and oxygen

FIG. 4A shows a signal at 5mA/cm²The first discharge and charge cycles of the battery of example 1 incorporating a 1M LiI-GBL electrolyte in the presence of ultra-high purity oxygen. LiI is chosen as an example of the metal halide salt, GBL is chosen as an example of the heterocyclic compound, and oxygen is chosen as an example of the oxidizing gas.

As shown in fig. 4B, the cell maintained excellent energy efficiency over 500 cycles ((s))>90%) and produces high output power: (>10mW/cm²). The specific capacity is normalized by the area of the electrode.

Example 3: rechargeable lithium iodide cell with ECL electrolyte and oxygen

FIG. 5A shows a signal at 5mA/cm²The first discharge and charge cycles of the cell of example 1 incorporating a 1M LiI-ECL electrolyte in the presence of ultra-high purity oxygen. Selecting LiI as an example of a metal halide salt, ECL is a heterocyclic compound, and oxygen is oxidizedA gas.

As shown in fig. 5B, the cell maintained high output power (>10mW/cm2) for more than 500 cycles. The specific capacity is normalized by the area of the electrode.

Example 4: rechargeable lithium iodide cell with THF electrolyte and oxygen

Fig. 6A shows the first discharge and charge cycles of the cell of example 1 incorporating 1M LiI-THF electrolyte in the presence of ultra-high purity oxygen at a current density of 5mA/cm 2. LiI was chosen as the metal halide salt, THF was chosen as an example of the heterocyclic compound, and oxygen was chosen as the oxidizing gas.

As shown in fig. 6B, the cell maintained high output power (>10mW/cm2) for more than 100 cycles. The specific capacity is normalized by the area of the electrode.

Comparative example 1: lithium iodide cell with GBL electrolyte and no oxygen

Fig. 7 shows the first discharge and charge cycle of the battery of example 1 incorporating a 1M LiI-GBL electrolyte in the absence of oxygen at a current density of 5mA/cm 2. The battery provided negligible discharge capacity in the first cycle using the same electrolyte solution as used in the battery of example 2. The coulomb efficiency was less than 10% in the first cycle and did not improve at all in the subsequent cycles. The specific capacity is normalized by the area of the electrode.

Comparative example 2: lithium iodide cell with TEGDME electrolyte and oxygen

FIG. 8 shows the voltage at 5mA/cm²The 50 th discharge and charge cycles of the cell of example 1 incorporating 1MLiI-TEGDME electrolyte in the presence of ultra-high purity oxygen. The cell provides negligible discharge capacity in the 50 th cycle under oxygen. Although the coulombic efficiency of the cell was greater than 90% in the first cycle, it decreased significantly from the next cycle and finally decreased to less than 10% in the 50 th cycle. The specific capacity is normalized by the area of the electrode. It is remarkable from the results of this example that when the cyclic compound in the electrolyte does not include an ether group, the battery performance is degraded.

Various embodiments of the present invention have been described. These and other embodiments of the invention are within the scope of the following claims.