CN115133123A - Electrolyte additive for improving performance of lithium-sulfur battery and high-performance lithium-sulfur battery - Google Patents

Abstract

The invention discloses an electrolyte additive for prolonging the cycle life of a lithium-sulfur battery and the lithium-sulfur battery with long service life, wherein the ionic additive is introduced into an electrolyte system of the lithium-sulfur battery, and the additive is characterized in that the additive can be ionized in the electrolyte system of the lithium-sulfur battery, cations of the additive and polysulfide anions dissolved in the electrolyte have stronger binding capacity and larger space volume, so that the migration of the polysulfide anions is slowed down, the migration rate of the anions in the electrolyte is faster than that of the polysulfide anions, and the anions can reach the surface of a lithium cathode to form electroneutrality, so that the migration of the dissolved polysulfide anions to the lithium cathode is hindered, and the shuttle effect is relieved; meanwhile, additive anions can participate in forming a protective solid-electrolyte interface to prevent the contact of dissolved polysulfide with a lithium negative electrode so as to reduce the loss of active substance sulfur; the application of the lithium-sulfur battery can greatly prolong the cycle life of the battery.

Description

An electrolyte additive for improving the performance of lithium-sulfur battery and high-performance lithium-sulfur battery

technical field

The invention belongs to the technical field of lithium-sulfur batteries, and in particular relates to an electrolyte additive for improving the performance of lithium-sulfur batteries and a high-performance lithium-sulfur battery.

Background technique

Commercial lithium-ion battery cathode materials such as cobalt- or nickel-based metal oxides LiCoO ₂ (LCO), LiNi _x Co _y M _z O ₂ (NCM), LiNi _x Co _y Al _z O ₂ (NCA), and olivine Structure LiFePO ₄ (LFP), the specific capacity does not exceed 280mAh g ^-1 , the energy density is less than 700Wh kg ^-1 , and the cost is high. Therefore, the development of new secondary batteries, especially new cathode materials, is an urgent task. Sulfur is a very abundant and inexpensive element. When used as a cathode material, its theoretical specific capacity and energy density are 1675mAh g ^-1 and 2510Wh kg ^-1 , respectively, making it a very promising alternative to commercial cathode materials for practical applications.

Although Li-S batteries have the above advantages, they still face some practical problems, such as the low electrical conductivity of S and its discharge products (Li ₂ S, Li ₂ S ₂ ), the presence of polysulfides during charge-discharge cycles The shuttle effect will lead to serious self-discharge, low Coulombic efficiency, short cycle life, large volume expansion (about 80%) involved in the conversion of S to Li ₂ S, and low utilization of the S cathode, among which the most urgent problem is to be solved and the most cited. A problem of concern is the shuttle effect of polysulfides. Among the common solutions to solve the polysulfide shuttle, improving the electrolyte system, such as adding electrolyte additives, using a new electrolyte system, etc. is the most convenient means of improvement, which is easier to use in practice without increasing the complexity of battery manufacturing sex. Quaternary ammonium salt, quaternary phosphorus salt or quaternary arsenic salt additives will effectively slow down the migration of dissolved polysulfides in the electrolyte to the negative electrode due to the strong binding effect of their cations and polysulfide anions, and the migration rate of their anions is higher than Polysulfide anions will first reach the vicinity of the negative electrode during the discharge process to form electrical neutrality, further slowing the kinetics of the migration of polysulfides to the negative electrode. The two effects work together to suppress the shuttle effect, prolong the cycle life of lithium-sulfur batteries, and improve Performance of lithium-sulfur batteries.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an electrolyte additive for improving the performance of a lithium-sulfur battery and a high-performance lithium-sulfur battery, which can improve the performance and prolong the life of the lithium-sulfur battery.

The object of the present invention is achieved through the following technical solutions:

The electrolyte additive for improving the performance of lithium-sulfur battery is characterized in that: the additive is an ionic additive, which can be dissociated into anions and cations in an electrolyte.

Optionally, the cation type of the additive is one of quaternary ammonium cation, quaternary phosphorus cation, and quaternary arsenic cation.

Optionally, the organic carbon chain in the quaternary ammonium cation, quaternary phosphorus cation, and quaternary arsenic cation is a carbon chain with a length of 4 carbons or more, such as an alkyl chain, an alkenyl chain, an alkynyl chain, an aromatic hydrocarbon or a fluorocarbon chain. One or more of alkyl chains, fluoroalkenyl chains, fluoroalkynyl chains, and fluoroaromatic hydrocarbons.

Optionally, the carbon chain is n-butyl, perfluoro-n-butyl, n-pentyl, perfluoro-n-pentyl, n-hexyl, perfluoro-n-hexyl, n-heptyl, perfluoro-n-heptyl, n-octyl , perfluoro-n-octyl, n-nonyl, perfluoro-n-nonyl, n-decyl, perfluoro-n-decyl, n-undecyl, perfluoro-n-undecyl, n-dodecyl, perfluoro-n-decyl One or more of dodecyl, n-hexadecyl, perfluoro-n-hexadecyl, phenyl, fluorophenyl, etc.

Optionally, the anion species of the additive are fluoride ion, chloride ion, bromide ion, iodide ion, cyanide ion, hydroxide ion, hexafluorophosphate ion, tetrafluoroborate ion, bis-trifluoromethanesulfonic acid One of imide ion, bis-fluorosulfonimide ion, bis-oxalate borate ion and difluorooxalate borate ion.

Optionally, the electrolyte solvent component for dissolving the additive according to claim 1 to claim 5 is 1,3-dioxane, 1,4-dioxane, ethylene glycol dimethyl ether, Diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, fluorocarbonic acid One or more of vinyl esters.

Optionally, the electrolyte solute components used for dissolving the additive according to claim 1 to claim 5 are lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-trifluoromethylsulfonylimide, bis-fluorosulfonylidene One or more of lithium amide, lithium bis-oxalate borate and lithium difluorooxalate borate.

A high-performance lithium-sulfur battery includes: a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is an electrolyte containing the aforementioned electrolyte additive for improving the cycle life of the lithium-sulfur battery.

Optionally, the positive electrode material is one of sulfur, carbon-sulfur composite material, lithium sulfide, and carbon-lithium sulfide composite material.

Optionally, the negative electrode material is one of metallic lithium, silicon-lithium alloy, pre-lithiated graphite, and metallic copper foil.

It can be seen from the above technical solutions that the present invention utilizes the characteristics of quaternary ammonium salts, quaternary phosphorus salts or quaternary arsenic salts to introduce such additives into the electrolyte system of traditional lithium-sulfur batteries. Due to the strong combination of quaternary ammonium salt cations and polysulfide anions It will effectively slow down the migration of dissolved polysulfides in the electrolyte to the negative electrode, as shown in Figure 1. At the same time, the migration rate of its anions is higher than that of polysulfide anions, and will first reach the vicinity of the negative electrode during the discharge process to form electrical neutrality. The kinetics of the migration of polysulfides to the negative electrode is further slowed down, and the two effects work together to suppress the shuttle effect and bring longer cycle life to the lithium-sulfur battery.

Description of drawings

1 is a schematic diagram of the mechanism of the electrolyte additive prepared in Example 1 on the inhibitory effect of the shuttle effect of polysulfide ions in the electrolyte system;

FIG. 2 is a comparison diagram of the constant current charge-discharge cycle performance of the lithium-sulfur battery assembled in Example 7 and the lithium-sulfur battery assembled in Comparative Example 1;

FIG. 3 is a comparison diagram of the galvanostatic charge-discharge cycle performance of the lithium-sulfur battery assembled in Example 7 and the lithium-sulfur batteries assembled in Comparative Example 2 and Comparative Example 3;

4 is a graph showing the cycle performance comparison between the lithium-sulfur battery assembled in Example 8 and the lithium-sulfur battery assembled in Comparative Example 4;

Fig. 5 is the electrochemical impedance comparison diagram of the cycle of the symmetrical battery assembled in Example 9 and the symmetrical battery assembled in Comparative Example 5;

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Detailed ways

In order to make the above-mentioned and other objects, features and advantages of the present invention more clearly demonstrated, the following specific embodiments of the present invention are described in detail, but are not used as a basis for any limitation of the invention.

The idea of the present invention is to introduce additives into the electrolyte system of lithium-sulfur battery, such additives are ionic additives, which can be dissociated into anions and cations in the electrolyte, and the improved electrolyte after the introduction of additives is used for lithium-sulfur batteries.

The cation species of the additive used in the present invention is one of quaternary ammonium cation, quaternary phosphorus cation and quaternary arsenic cation.

The organic carbon chain in the quaternary ammonium cation, quaternary phosphorus cation or quaternary arsenic cation in the additive used in the present invention is a carbon chain with a length of 4 carbons or more, such as an alkyl chain, an alkenyl chain, an alkynyl chain, an aromatic hydrocarbon or a fluorocarbon chain One or more of alkyl chains, fluoroalkenyl chains, fluoroalkynyl chains, and fluoroaromatic hydrocarbons. The organic carbon chain on the quaternary ammonium cation, quaternary phosphorus cation or quaternary arsenic cation in the additive used in the present invention is n-butyl, perfluoro-n-butyl, n-pentyl, perfluoro-n-pentyl, n-hexyl, perfluoro-n-hexyl, n-heptyl, perfluoro-n-heptyl, n-octyl, perfluoro-n-octyl, n-nonyl, perfluoro-n-nonyl, n-decyl, perfluoro-n-decyl, n-undecyl, perfluoro-n-decyl One or more of monoalkyl, n-dodecyl, perfluoro-n-dodecyl, n-hexadecyl, perfluoro-n-hexadecyl, phenyl, fluorophenyl, etc.

The additive anions used in the present invention are fluoride ion, chloride ion, bromide ion, iodide ion, cyanide ion, hydroxide ion, hexafluorophosphate ion, tetrafluoroborate ion, bis-trifluoromethanesulfonimide One of the ion, bis-fluorosulfonimide ion, bisoxalate borate ion, and difluorooxalate borate ion.

The electrolyte solvent components used in the present invention for dissolving additives are 1,3-dioxane, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol One or more of dimethyl ether, tetraethylene glycol dimethyl ether, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate.

The electrolyte solute components used for dissolving additives in the present invention are lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-trifluoromethylsulfonimide, lithium bis-fluorosulfonimide, lithium bisoxalate borate, and difluorooxalate borate One or more of lithium.

When the lithium-sulfur battery is assembled with the aforementioned electrolyte containing additives, the positive electrode material may be sulfur, carbon-sulfur composite material, lithium sulfide, or carbon-lithium sulfide composite material.

When the lithium-sulfur battery is assembled with the aforementioned electrolyte containing additives, the negative electrode material can be metal lithium, silicon-lithium alloy, pre-lithiated graphite, or metal copper foil.

The present invention will be further described below through specific examples and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, conventional materials and conventional instruments, which can be purchased through normal channels.

Example 1:

The additive cation used in this example is cetyltrioctylammonium ion, the anion is iodine ion, the electrolyte solvent is 1,3-dioxane and ethylene glycol dimethyl ether, and the electrolyte solute is bis-trifluoro lithium methylsulfonylimide;

Mix 1,3-dioxane and ethylene glycol dimethyl ether in a volume ratio of 1:1, dissolve lithium bis-trifluoromethanesulfonimide in it, and prepare a solution of 1 mol L ^-1 , which is electrolyte;

The additive hexadecyl trioctyl ammonium iodide crystal was dissolved in the above electrolyte, and the improved electrolyte was used in a lithium-sulfur battery, and the additive content was 0.5 mol L ^-1 .

Example 2:

The additive cation used in this example is tetrabutylammonium ion, the anion is iodine ion, the electrolyte solvent is 1,3-dioxane and ethylene glycol dimethyl ether, and the electrolyte solute is bis-trifluoromethylsulfonyl Lithium imide;

Mix 1,3-dioxane and ethylene glycol dimethyl ether in a volume ratio of 1:1, dissolve lithium bis-trifluoromethanesulfonimide in it, and prepare a solution of 1 mol L ^-1 , which is electrolyte;

The additive tetrabutylammonium iodide crystal was dissolved in the above electrolyte, and the improved electrolyte was used in a lithium-sulfur battery, and the additive content was 0.5 mol L ^-1 .

Example 3:

The additive cation used in this example is perfluorohexadecyl trioctyl ammonium ion, the anion is iodine ion, the electrolyte solvent is 1,3-dioxane and ethylene glycol dimethyl ether, and the electrolyte solute is bis- Lithium trifluoromethylsulfonimide;

Mix 1,3-dioxane and ethylene glycol dimethyl ether in a volume ratio of 1:1, dissolve lithium bis-trifluoromethanesulfonimide in it, and prepare a solution of 1 mol L ^-1 , which is electrolyte;

The additive perfluorohexadecyl trioctyl ammonium iodide crystal is dissolved in the above electrolyte, and the improved electrolyte is used in a lithium-sulfur battery, and the additive content is 0.5mol L ^-1 .

Example 4:

The additive cation used in this example is perfluorohexadecyl trioctyl ammonium ion, the anion is hydroxide ion, the electrolyte solvent is 1,3-dioxane and ethylene glycol dimethyl ether, and the electrolyte solute is Lithium bis-trifluoromethylsulfonimide;

Mix 1,3-dioxane and ethylene glycol dimethyl ether in a volume ratio of 1:1, dissolve lithium bis-trifluoromethanesulfonimide in it, and prepare a solution of 1 mol L ^-1 , which is electrolyte;

The additive hexadecyl trioctyl ammonium hydroxide crystal was dissolved in the above electrolyte, and the improved electrolyte was used in a lithium-sulfur battery, and the additive content was 0.5 mol L ^-1 .

Example 5:

The additive cation used in this embodiment is perfluorohexadecyltrioctylammonium ion, the anion is iodine ion, the electrolyte solvent is dimethyl carbonate and ethylene carbonate, and the electrolyte solute is lithium hexafluorophosphate;

Use dimethyl carbonate and ethylene carbonate to mix at a volume ratio of 1:1, dissolve lithium hexafluorophosphate, and prepare a solution of 1mol L ^-1 , which is an electrolyte;

The additive hexadecyl trioctyl ammonium iodide crystal was dissolved in the above electrolyte, and the improved electrolyte was used in a lithium-sulfur battery, and the additive content was 0.5 mol L ^-1 .

Example 6:

The additive cation used in this example is tetrabutylammonium ion, the anion is hexafluorophosphate ion, the electrolyte solvent is 1,3-dioxane and ethylene glycol dimethyl ether, and the electrolyte solute is bis-trifluoromethane Lithium sulfonimide;

Mix 1,3-dioxane and ethylene glycol dimethyl ether in a volume ratio of 1:1, dissolve lithium bis-trifluoromethanesulfonimide in it, and prepare a solution of 1 mol L ^-1 , which is electrolyte;

The additive tetrabutylammonium hexafluorophosphate was dissolved in the above electrolyte as an additive, and the improved electrolyte was used in a lithium-sulfur battery, and the additive content was 0.5 mol L ^-1 .

Example 7:

Using the electrolyte prepared in Example 1, a lithium-sulfur battery was assembled by a conventional assembly process, wherein a 20 μm thick polypropylene separator was used as the separator, a carbon-sulfur composite material with a sulfur content of 60% was used as the positive electrode material, and metallic lithium was used as the negative electrode.

Comparative Example 1:

The difference between Comparative Example 1 and Example 7 is that the lithium-sulfur battery electrolyte without additives was used when assembling the lithium-sulfur battery, that is, 1,3-dioxane and ethylene glycol dimethyl ether were used in a volume ratio of 1. : 1 mixing, dissolving lithium bis-trifluoromethanesulfonimide in it, to prepare an electrolyte of 1 mol L ^-1 .

Comparative Example 2:

The difference between Comparative Example 2 and Example 7 is that the additive concentration of the additive in the electrolyte used when assembling the lithium-sulfur battery is 0.1 mol L ⁻¹ .

Comparative Example 3:

The difference between Comparative Example 3 and Example 7 is that the additive concentration of the additive in the electrolyte used when assembling the lithium-sulfur battery is 2 mol L ⁻¹ .

Example 8:

Using the electrolyte prepared in Example 1, a lithium-sulfur battery was assembled by a conventional assembly process, wherein the separator was a polypropylene separator with a thickness of 20 μm, the positive electrode material was a carbon-sulfur composite material with a sulfur content of 60%, and the negative electrode was pre-lithiated graphite.

Comparative Example 4:

The difference between Comparative Example 4 and Example 8 is that the lithium-sulfur battery electrolyte without additives is used when assembling the lithium-sulfur battery, that is, 1,3-dioxane and ethylene glycol dimethyl ether are used in a volume ratio of 1. : 1 mixing, dissolving lithium bis-trifluoromethanesulfonimide in it, to prepare an electrolyte of 1 mol L ^-1 .

Example 9:

Using the electrolyte prepared in Example 1, a symmetric battery was assembled by a conventional assembly process, wherein the separator was a polypropylene separator with a thickness of 20 μm, and metal lithium electrodes were used for both electrodes.

Comparative Example 5:

The difference between Comparative Example 5 and Example 9 is that the lithium-sulfur battery electrolyte without additives is used when assembling the lithium-sulfur battery, that is, 1,3-dioxane and ethylene glycol dimethyl ether are used in a volume ratio of 1. : 1 mixing, dissolving lithium bis-trifluoromethanesulfonimide in it, to prepare an electrolyte of 1 mol L ^-1 . The batteries assembled in Examples 7, 8 and Comparative Examples 1 to 4 were characterized by constant current charge and discharge, and the symmetrical batteries assembled in Example 9 and Comparative Example 5 were subjected to electrochemical impedance testing.

FIG. 1 is a schematic diagram of the mechanism of the inhibitory effect of the electrolyte additive prepared in Example 1 on the shuttle effect of polysulfide ions in the electrolyte system.

FIG. 2 is a comparison diagram of the constant current charge-discharge cycle performance of the lithium-sulfur battery assembled in Example 7 and the lithium-sulfur battery assembled in Comparative Example 1. It can be seen from FIG. 2 that the lithium-sulfur battery assembled in Example 7 The cycle stability is significantly better than that of the lithium-sulfur battery assembled in Comparative Example 1, and the discharge specific capacity remains 80% of the initial capacity after 200 charge-discharge cycles. Even after 1000 charge-discharge cycles, 55% of the initial capacity could still be maintained, while the lithium-sulfur battery assembled in Comparative Example 1 was only 35% of its capacity after 100 charge-discharge cycles, indicating that the lithium-sulfur battery prepared in Example 1 The additives have a great positive effect on prolonging the cycle life of lithium-sulfur batteries.

3 is a comparison diagram of the constant current charge-discharge cycle performance of the lithium-sulfur battery assembled in Example 7 and the lithium-sulfur batteries assembled in Comparative Examples 2 and 3. It can be seen from FIG. 3 that the lithium-sulfur battery assembled in Example 7 The cycle stability of the lithium-sulfur battery is significantly better than that of the lithium-sulfur battery assembled in Comparative Example 2. In addition, although the cycle stability of the lithium-sulfur battery assembled in Comparative Example 3 is slightly better than that of the lithium-sulfur battery assembled in Example 7, its The capacity is always lower than that of the lithium-sulfur battery assembled in Comparative Example 7, indicating that the additive amount of the additive prepared in Example 1 has a certain influence on the cycle stability of the battery. When the additive content is low, the effect is not obvious. The increase in the viscosity of the electrolyte system leads to a certain hindering of ion migration, which will negatively affect the charge-discharge capacity.

FIG. 4 is a comparison chart of the cycle performance of the lithium-sulfur battery assembled in Example 8 and the lithium-sulfur battery assembled in Comparative Example 4. It can be seen from FIG. 4 that the cycle stability of the lithium-sulfur battery assembled in Example 8 is obviously better. For the lithium-sulfur battery assembled in Comparative Example 4, it is shown that the additive prepared in Example 1 has a great positive effect on prolonging the cycle life of the lithium-sulfur battery, and it also shows that this additive is suitable for lithium-ion batteries using pre-lithiated graphite as the negative electrode. Sulfur battery system.

FIG. 5 is a comparison diagram of the electrochemical impedance of the symmetrical battery assembled in Example 9 and the symmetrical battery assembled in Comparative Example 5. It can be seen from FIG. 5 that the solution impedance of the symmetrical battery assembled in Example 9 (R _s ) and mass transfer impedance (R _ct ) were both smaller than those of the symmetric battery assembled in Comparative Example 5, indicating that the additive prepared in Example 1 had an improved electrical conductivity of the battery system.

The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features according to the disclosed technical contents without creative work. Modifications, replacements and modifications are all within the protection scope of the present invention.

Claims (10)

1. Promote electrolyte additive of lithium sulphur battery performance, its characterized in that: the additive is an ionic additive which can be dissociated into anions and cations in the electrolyte.

2. The additive for an electrolyte solution for enhancing performance of a lithium sulfur battery according to claim 1, wherein: the cationic species of the additive is one of quaternary ammonium cation, quaternary phosphorus cation and quaternary arsenic cation.

3. The additive for an electrolyte to improve performance of a lithium sulfur battery according to claim 1 or 2, wherein: the organic carbon chain in the quaternary ammonium cation, the quaternary phosphonium cation and the quaternary arsenic cation is a carbon chain with the length of 4 carbons or more, such as one or more of an alkyl chain, an alkenyl chain, an alkynyl chain, an arene or a fluoroalkyl chain, a fluoro-alkenyl chain, a fluoro-alkynyl chain and fluoro-arene.

4. The electrolyte additive for improving performance of a lithium sulfur battery according to claim 1, 2 or 3, wherein: the carbon chain is one or more of n-butyl, perfluor n-butyl, n-pentyl, perfluor n-pentyl, n-hexyl, perfluor n-hexyl, n-heptyl, perfluor n-heptyl, n-octyl, perfluor n-octyl, n-nonyl, perfluor n-nonyl, n-decyl, perfluor n-decyl, n-undecyl, perfluor n-undecyl, n-dodecyl, perfluor n-dodecyl, n-hexadecyl, perfluor n-hexadecyl, phenyl, fluorophenyl and the like.

5. The additive for an electrolyte solution for enhancing performance of a lithium sulfur battery according to claim 1, wherein: the anion species of the additive is one of fluoride ion, chloride ion, bromide ion, iodide ion, cyano ion, hydroxide ion, hexafluorophosphate ion, tetrafluoroborate ion, bis-trifluoromethylsulfonyl imide ion, bis-fluorosulfonyl imide ion, bis-oxalato borate ion and difluorooxalato borate ion.

6. The additive for an electrolyte solution for enhancing performance of a lithium sulfur battery according to claim 1, wherein: the electrolyte solvent for dissolving the additive according to claims 1 to 5 is one or more selected from 1, 3-dioxolane, 1, 4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate and fluoroethylene carbonate.

7. The additive for an electrolyte to enhance performance of a lithium sulfur battery according to claim 1, wherein: the solute component for dissolving the electrolyte according to the claims 1 to 5 is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-trifluoromethylsulfonyl imide, lithium bis-fluorosulfonyl imide, lithium bis-oxalato borate and lithium difluoro-oxalato borate.

8. A high performance lithium sulfur battery comprising: positive pole, negative pole, electrolyte, its characterized in that: the electrolyte is prepared by the method for improving the cycle life of the lithium-sulfur battery according to any one of claims 1 to 7, and contains an electrolyte additive.

9. The high performance lithium sulfur battery of claim 8 wherein: the positive electrode material is one of sulfur, a carbon-sulfur composite material, lithium sulfide and a carbon-lithium sulfide composite material.

10. The high performance lithium sulfur battery of claim 8 wherein: the negative electrode material is one of metal lithium, silicon-lithium alloy, pre-lithiated graphite and metal copper foil.

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