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Lithium-sulfur battery

A lithium-sulfur battery, sulfur-based technology, applied in lithium batteries, secondary batteries, non-aqueous electrolyte batteries, etc., can solve the problems of low specific capacity, large amount of dissolved, and too late to convert sulfur intermediate products.

Inactive Publication Date: 2021-05-07
CHINA AVIATION LITHIUM BATTERY RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, when the liquid injection volume is high (liquid sulfur ratio 15-10:1), the amount of polysulfide dissolved in the electrolyte is relatively large during the first discharge process, and some polysulfide intermediate products are too late to be converted, and the specific capacity of the first discharge is low. ; Diffusion to the negative electrode causes loss of active material and shortens battery life
When the liquid injection volume is low (liquid sulfur ratio 5-2.6:1), the infiltration of the active material by the electrolyte is carried out gradually with the discharge process, the loss of the active material is small, and the initial discharge capacity is high, but due to the total electrolyte The amount is small, and it is gradually consumed by the lithium metal negative electrode during the cycle, resulting in a cliff-like diving phenomenon in the capacity of the battery after dozens of cycles

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0026]Mix sulfur / carbon cathode material, conductive agent (SP) and liquid retaining material (PVDF+PMMA, PVDF:PMMA (mass ratio)=70:30) in tetrahydrofuran according to 90:2:8, and then add the above The total mass of materials (excluding solvent) is 0.5 wt% ammonium bicarbonate (pore forming agent), and all the above materials are mixed and stirred for 0.5 h at 20° C. to obtain positive electrode slurry. The slurry was coated on an aluminum foil, and dried in vacuum at 60° C. for 12 hours to obtain a porous lithium-sulfur battery positive electrode Z-1.

[0027] The obtained positive electrode Z-1 was punched into a 60×75mm positive electrode sheet, and a 200 μm thick 65×80mm lithium strip was used as the negative electrode. The diaphragm was selected from celgard2400 diaphragm, and the electrolyte was 1M LiTFSI dissolved in DOL / DME=1:1(V / V), electrolyte and active sulfur mass ratio E / S=7:1 (liquid sulfur ratio, "liquid sulfur ratio" described in embodiment 1-7 refers to the ...

Embodiment 2

[0029] Sulfur / carbon cathode material, conductive agent (SP) and liquid retaining material (PEO+PMMA, PEO:PMMA (mass ratio)=50:50) according to 70:10:20, in dimethylformamide (DMF) After uniform mixing, ammonium bicarbonate (pore forming agent) accounting for 1 wt% of the total mass of the above materials (without solvent) was added, and all the above materials were mixed and stirred at 40°C for 4 hours to obtain positive electrode slurry. The slurry was coated on an aluminum foil, and vacuum-dried at 60° C. for 36 h to obtain a porous lithium-sulfur battery positive electrode Z-2.

[0030] The obtained positive electrode Z-2 was punched into a 60×75mm positive electrode sheet, and a 200 μm thick 65×80mm lithium strip was used as the negative electrode. The diaphragm was selected from celgard2400 diaphragm, and the electrolyte was 1M LiTFSI dissolved in DOL / DME=1:1(V / V), the mass ratio of electrolyte to active sulfur E / S=10:1 (liquid sulfur ratio), assembled into a monolithic...

Embodiment 3

[0032] Mix sulfur / carbon cathode material, conductive agent (SP) and liquid retaining material (LA133+PEG, LA133:PEG (mass ratio) = 60:40) in pure water at 80:5:15, then add The total mass of the above materials (without solvent) is 3 wt% of glucose, and at the same time, 2 wt% of the glucose mass of yeast (pore-forming agent) is added, and all the above materials are mixed and stirred at 30°C for 2 hours to obtain a fermented positive electrode slurry. The slurry was coated on an aluminum foil, and dried in vacuum at 60° C. for 24 h to obtain a porous lithium-sulfur battery positive electrode Z-3.

[0033] The obtained positive electrode Z-3 was stamped into a 60×75mm positive electrode sheet, and a 200 μm thick 65×80mm lithium strip was used as the negative electrode. The diaphragm was selected from celgard2400 diaphragm, and the electrolyte was 1M LiTFSI dissolved in DOL / DME=1:1(V / V), the mass ratio of electrolyte to active sulfur E / S=15:1, assembled into a monolithic batt...

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Abstract

The invention discloses a lithium-sulfur battery. The battery comprises a positive plate, a negative plate, a diaphragm and a liquid retention material; the positive plate comprises a current collector and a positive active material layer, and the positive active material layer comprises a sulfur-based positive active material; and the electrolyte is stored in the electrolyte retention material, and the electrolyte can be reversibly stored and released in the charging and discharging process of the electrolyte retention material. The lithium-sulfur battery comprises the electrolyte retention material, the electrolyte retention material can reversibly store and release the electrolyte in the charging and discharging process, the volume of the positive electrode is expanded along with the discharging process, the electrolyte retention material in the battery is gradually pressed, and the electrolyte is forced to be gradually released along with the discharging depth, so the excessive dissolution and loss of polysulfide in the discharge process under high liquid injection quantity are relieved, and the first discharge capacity of the battery is effectively improved. In addition, sufficient electrolyte in the electrolyte retention material can support normal charging and discharging circulation of the battery, and the problem of circulation diving under the condition of poor electrolyte is solved.

Description

technical field [0001] The invention relates to the field of chemical power sources, in particular to lithium-sulfur batteries. Background technique [0002] Due to its high theoretical capacity and specific energy, and the abundance of elemental sulfur in the earth, it has the characteristics of low price and environmental friendliness, and is widely considered to be the development direction of the next generation of high energy density batteries Research hotspots. [0003] However, when the liquid injection volume is high (liquid sulfur ratio 15-10:1), the amount of polysulfide dissolved in the electrolyte is relatively large during the first discharge process, and some polysulfide intermediate products are too late to be converted, and the specific capacity of the first discharge is low. ; Diffusion to the negative electrode causes loss of active material and shortens battery life. When the liquid injection volume is low (liquid sulfur ratio 5-2.6:1), the infiltration ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/052H01M10/42
CPCH01M10/052H01M10/4235Y02E60/10
Inventor 闫银贤彭祖铃
Owner CHINA AVIATION LITHIUM BATTERY RES INST CO LTD
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