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Method for improving capacity and cyclic stability of lithium-sulfur battery cathode material

A technology for cycle stability, lithium-sulfur batteries, applied in battery electrodes, lithium batteries, non-aqueous electrolyte batteries, etc., can solve problems such as the impact of little binder battery performance, reduce synthesis costs, avoid preparation processes, enhance The effect of stability

Inactive Publication Date: 2014-06-25
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, common single-component polymer materials such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) are generally used in laboratories and industrial production, and there are few types of binders. Research report on the influence of components on battery performance

Method used

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  • Method for improving capacity and cyclic stability of lithium-sulfur battery cathode material
  • Method for improving capacity and cyclic stability of lithium-sulfur battery cathode material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment example 1

[0021] Sulfur and activated porous conductive carbon (the molar ratio of sulfur and activated porous conductive carbon is 1:1) are weighed in proportion, and a certain amount of binder (PVP: PEO=1:1), put it into the ball mill tank, add a certain amount of balls according to the ball-to-material ratio of 2:1, add a small amount of water to facilitate the dissolution of the binder, perform ball milling in the ball mill, and set the speed of the ball mill After 2 hours of ball milling at 20,000 rpm, the abrasive was taken out. After separation, the cathode material of the lithium-sulfur electrode is obtained.

[0022] Preparation of positive electrode sheet and test of coin cell. The ball-milled mixture is used as the active material of the electrode, and the slurry is prepared with water. The slurry is coated on the aluminum foil of the current collector, and then vacuum-dried at 60°C for 8-10 hours to remove the solvent and moisture, and compacted under a pressure of 8-12MPa...

Embodiment example 2

[0025] Sulfur and activated porous conductive carbon (wherein the molar ratio of sulfur and activated porous conductive carbon is 9:1) are weighed in proportion, and a certain amount is added according to the molar ratio of sulfur, carbon, and binder in a ratio of 9:1:1 Put the binder (PVP:PEO=1:4) into the ball mill tank, add a certain amount of balls according to the ball-to-material ratio of 2:1, and add a small amount of water to facilitate the dissolution of the binder. Carry out ball milling, set the rotating speed of the ball mill to 20000 rev / min, after ball milling for 4 hours, take out the abrasive. After separation, the cathode material of the lithium-sulfur electrode is obtained. After the battery is assembled according to the method of Example 1, at 100mA g -1 The performance test was carried out under the current density, and the first discharge specific capacity was 923.9mAh g -1 , the discharge specific capacity remained at 817.7mAh g after 20 cycles -1 .

Embodiment example 3

[0027] Weigh sulfur, acetylene black and binder (the molar ratio of sulfur, acetylene black and binder is 6:4:1) in proportion, the binder is (PVP:PEO=1:9), put In the ball mill tank, add a certain amount of balls according to the ball-to-material ratio of 3:1, add a small amount of water to facilitate the dissolution of the binder, perform ball milling in the ball mill, set the speed of the ball mill to 20,000 rpm, and mill for 10 hours After that, remove the abrasive. After separation, the cathode material of the lithium-sulfur electrode is obtained. After the battery is assembled according to the method of Example 1, at 100mA g -1 The performance test was carried out under the current density, and the first discharge specific capacity was 1239.1mAh g -1 , the discharge specific capacity remained at 957.7mAh g after 20 cycles -1 .

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Abstract

The invention discloses a method for improving the capacity and cyclic stability of a lithium-sulfur battery cathode material, and is characterized by providing a novel composite adhesive formula and a preparation process of a cathode material and aiming to prepare a lithium-sulfur battery cathode material with high specific capacity and high energy density. The method comprises the steps of mixing activated porous conductive carbon and other conductive agents with sulfur according to a certain ratio, adding a certain quantity of multi-component high-molecular polymer as an adhesive and acetonitrile as a solvent, mixing multi-component high-molecular polymer and acetonitrile with a stainless steel ball with a certain diameter, and treating the mixture for several hours by using a ball milling method to obtain paste of the lithium-sulfur battery cathode material. The adhesive not only can be used for bonding an active material, but also can play a role in coating sulfur and sulfides; the adhesive is added in an early preparation stage to ensure that a uniformly-distributed and thickness-controllable thin polymer layer is formed on the surface of each of sulfur and conductive agent through the ball milling method, so that the direct contact among electrolyte, sulfur and a compound thereof is effectively avoided, the dissolution of sulfur and the decomposition of electrolyte are reduced, and the cyclic stability of a lithium-sulfur battery is improved.

Description

technical field [0001] The invention belongs to the technical field of high-energy secondary battery preparation, and in particular relates to a preparation process of a high-energy lithium-sulfur battery cathode material, a novel binder and a coating method thereof. Background technique [0002] Lithium-ion secondary battery is a chemical power source with the best comprehensive performance at present, and is widely used in portable electronic products such as mobile phones, notebooks and cameras. However, with the emergence and popularization of various new electric vehicles, lithium-ion batteries are required to have higher power density and energy density. The existing lithium-ion battery technology can no longer meet the above market requirements, so the development and design of new secondary battery reaction systems and related materials has become the key to the future development of high-energy secondary battery technology. Recently, as an emerging secondary batter...

Claims

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Application Information

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IPC IPC(8): H01M4/139
CPCH01M4/139H01M4/622H01M4/623H01M10/052Y02E60/10
Inventor 曹传宝朱有启张君婷
Owner BEIJING INSTITUTE OF TECHNOLOGYGY