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Double-effect composite membrane used for lithium sulphur battery and preparation method thereof

A lithium-sulfur battery and composite separator technology, which is applied in battery pack components, circuits, electrical components, etc., to achieve the effects of improving specific energy, low cost, and prolonging cycle life

Active Publication Date: 2018-08-28
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to propose a double-effect composite separator for lithium-sulfur batteries and a preparation method thereof, so as to solve the above-mentioned problems existing in existing lithium-sulfur batteries, especially when cycling under high-load and high-rate conditions

Method used

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Examples

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Effect test

preparation example Construction

[0035] At the same time, the present invention proposes a preparation method for the above-mentioned composite diaphragm, including: compounding the polar material with catalytic conversion capability and a conductive carbon-based material to prepare the functional compound; combining the functional compound with the adhesive The binder is co-dispersed in the dispersant to obtain a slurry; the obtained slurry is loaded on a porous insulating film by coating or filtering, and the composite battery separator is obtained after drying. The specific preparation method is as follows:

[0036] The preparation method of the first double-effect composite diaphragm for lithium-sulfur battery provided by the present invention comprises the following steps:

[0037] 1) preparing the functional compound: co-dispersing the polar material with catalytic conversion capability and the conductive carbon-based material in the dispersant according to the ratio described in claim 1, to obtain a dis...

Embodiment 1

[0057] Mix 9.5g cobalt disulfide nanoparticles with 0.5g redox graphene powder evenly, add 0.5g binder PTFE, the resulting mixture is dispersed in N-methylpyrrolidone, after 2h ultrasonic treatment and 2 days of stirring, the obtained slurry The material is coated on Celgard 2400, a common commercial battery separator polypropylene, with a 200-micron doctor blade, and then dried to obtain a double-effect composite separator. The functional layer of the separator has a loading capacity of about 0.3 mg cm -2 . The separator was prepared into a button battery and a pouch battery using the positive electrode, negative electrode and electrolyte system used in Comparative Example 1, respectively.

[0058] After testing, under the charge and discharge rate of 0.5C, the discharge capacity of the button battery installed in the first circle exceeds 1300mAhg -1 , the capacity exceeds 900mAh g after 100 cycles -1 , the average Coulombic efficiency is greater than 99%, and the cycle cap...

Embodiment 2

[0060]Dissolve 0.25g of nickel nitrate and iron nitrate in dimethyl sulfoxide, add 1g of multi-walled carbon nanotube powder, then add dropwise an aqueous solution of sodium hydroxide to the solution to make nickel-iron layered double hydroxide (Ni, Fe -LDH) grows on the surface of carbon tubes. Then filter and freeze-dry to obtain the composite of Ni, Fe-LDH and carbon tube. Take 1g of the composite, disperse it with 0.1g of carboxymethyl cellulose in aqueous ethanol solution, and deposit the composite on the surface of the glass fiber membrane by suction filtration. Functional layer, the loading capacity of the functional layer is about 0.2mg cm -2 . The separator was prepared into a button battery and a pouch battery using the positive electrode, negative electrode and electrolyte system used in Comparative Example 1, respectively.

[0061] After testing, under the charge and discharge rate of 0.5C, the discharge capacity of the button battery installed in the first circl...

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Abstract

The invention provides a double-effect composite membrane used for a lithium sulphur battery and a preparation method thereof. The membrane is composed of a functional composite layer and porous insulating film. The functional composite layer is a composite of conductive carbon base materials, polar materials and a binder, wherein the mass fraction of the conductive carbon base materials and polarmaterials is 5%-90% and 5%-90% respectively. The preparation method comprises the steps that the conductive carbon base materials and the polar materials are used for preparing the functional composite layer, the functional composite layer is loaded on the porous insulating film, and surface loading capacity of the functional composite layer is 0.1-3.0 mg cm-2. The composite membrane in the lithium sulphur battery regulates and controls reaction and deposition behaviors of active substances in different charge-discharge stages and significantly improves the utilization and stability of the active substances of the lithium sulphur battery. Compared with ordinary commercial polymer battery membranes, the composite membrane prolongs the cycle life of the lithium sulphur battery and improvesspecific energy, positive discharge capacity and coulombic efficiency. The method is simple in operation, is beneficial to large-scale preparation, and facilities wide commercial application of the high-energy density lithium sulphur battery.

Description

technical field [0001] The invention relates to a composite functional separator for lithium-sulfur batteries and a preparation method thereof, belonging to the technical field of lithium-sulfur batteries. Background technique [0002] High energy density secondary batteries are of great significance and great value in the development of human society. With the continuous development of electric vehicles and portable devices, people urgently need high-energy-density secondary batteries with higher energy density and longer battery life to meet the needs of production and life. [0003] Among all kinds of secondary battery systems with high energy density, the lithium-sulfur battery system with elemental sulfur and metallic lithium as positive and negative active materials has outstanding advantages. During the charge and discharge process, sulfur undergoes redox reactions between 0 valence and -2 valence, such a multi-electron conversion reaction makes the sulfur cathode ha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M50/403H01M50/451
CPCH01M50/403H01M50/449Y02E60/10
Inventor 黄佳琦谢瑾彭翃杰张强
Owner TSINGHUA UNIV
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