Battery diaphragm material and its preparation method and application

A battery separator and coating material technology, applied in fuel cells, battery electrodes, secondary batteries, etc., can solve problems such as failure, low capacity of lithium-ion batteries, deterioration of negative electrode performance, etc., to improve Coulomb efficiency, improve cycle performance, The effect of increasing the specific capacity

Active Publication Date: 2021-11-12
SOUTH CHINA NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

With the continuous charge and discharge under high temperature conditions, the redox reaction between the positive electrode material and the interface electrolyte will continue, and even the electrolyte will be decomposed, and metal ions will be deposited on the negative electrode, resulting in the deterioration of the negative electrode performance, and finally lead to the failure of the lithium-ion battery due to its low capacity.

Method used

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  • Battery diaphragm material and its preparation method and application
  • Battery diaphragm material and its preparation method and application
  • Battery diaphragm material and its preparation method and application

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preparation example Construction

[0026] A method for preparing a battery diaphragm coating material of the present invention, comprising: dissolving PVDF and covalent organic framework material in N-methylpyrrolidone and stirring evenly; said PVDF, covalent organic framework material and N-methylpyrrolidone The mass ratio of pyrrolidone is 20:(70-85):(5-10). Among them, PVDF has good chemical stability and temperature characteristics, excellent mechanical properties and processability, and has a positive effect on improving bonding performance. If other types of resins are used instead of PVDF, such as sodium hydroxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR), if CMC is too brittle, it will cause the pole piece to drop powder, and the dispersion effect of SBR is not good, which will affect the cycle performance of the material. negative impacts.

[0027] Preferably, the organic solvent is a mixed solution of 1,4-dioxane and mesitylene.

[0028] Specifically, the covalent organic framework mate...

Embodiment 1

[0037] Prepare covalent organic framework materials (Covalent Organic Frameworks, COFs), by mass percentage, its raw material components are as follows:

[0038] 1,3,5-tris(4-aminophenyl)benzene (TPB) 54.6%,

[0039] 2,5-dimethoxy-1,4-dicarboxybenzene (DMTP) 45.4%,

[0040] Concrete preparation steps are as follows:

[0041] Dissolve 1,3,5-tris(4-aminophenyl)benzene (TPB) and 2,5-dimethoxy-1,4-dimethylaldehydebenzene (DMTP) in organic solvent 1,4-dioxane Ring and mesitylene, ultrasonic, control ultrasonic time is 5-10 minutes. Add 1-3% acetic acid. Then, under an inert protective atmosphere, the mixture was reacted at 120° C. for 3 days, and the obtained product was a yellow solid. Finally, the obtained yellow solid was repeatedly washed with 1,4-dioxane, tetrahydrofuran and absolute ethanol for 2-3 times, and then dried in vacuum for 12 hours. The stated percentages are all mass percentages.

[0042] After detection, the transmission electron microscope scanning image (...

Embodiment 2

[0050] Example 2 Application of COFs Modified Diaphragm: NCM811 as a cathode material for a lithium ion battery diaphragm

[0051] The COFs modified diaphragm prepared in Example 1 was cut into a diameter of 18 mm, used as a diaphragm for a lithium-ion battery, and NCM811 was used as a positive electrode material to assemble the battery.

[0052] After the separator was assembled into a battery, the cyclic voltammetry was measured. Figure 4 It is the cycle diagram of NCM811. It can be seen from the comparison that at room temperature, the half-cell prepared by mixing the separator synthesized by COFs and the half-cell prepared by unmixed CoFs are charged and discharged three times at a rate of 0.3C. The specific capacity Both remain at about 200mAh / g, and the Coulombic efficiency is 100% after 3 cycles, and when the two batteries are charged and discharged 150 times at a rate of 1C, it is found that the specific capacity of the half-cell prepared by this method is between 200...

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Abstract

The invention provides a method for preparing a battery diaphragm coating material, comprising: dissolving PVDF and a covalent organic framework material in an organic solvent and stirring evenly; the ratio of the PVDF, the covalent organic framework material and N-methylpyrrolidone For 20: (70‑85): (5‑10). Applying it to the preparation of lithium-ion battery separators can effectively solve the problem of metal dissolution when transition metal oxides are used as positive electrode materials. The prepared separator can effectively absorb metal ions during charging and discharging, preventing them from depositing on the negative electrode, thereby improving Cyclic performance of transition metal oxide cathode materials.

Description

technical field [0001] The invention belongs to the field of battery materials, and in particular relates to a battery diaphragm material and a preparation method and application thereof. Background technique [0002] As a secondary battery, lithium-ion battery has the advantages of high voltage, large specific energy, long cycle life, good safety performance, small self-discharge, fast charging speed, etc. It is currently the battery system with the best comprehensive performance and a modern high-performance battery system. A typical representative of the battery, it is widely used in the power support of information technology, electric vehicles and hybrid vehicles, aerospace and other fields. Lithium-ion batteries have been developed for decades. [0003] A lithium-ion battery is composed of a positive electrode, a negative electrode, a separator, and an electrolyte, and both the positive and negative electrode materials can intercalate and extract lithium ions. It wor...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M50/457H01M50/426H01M50/417H01M50/403H01M10/0525
CPCH01M10/0525H01M50/411H01M50/44H01M50/461H01M50/403Y02E60/10H01M8/0228H01M50/449H01M4/133H01M4/131H01M4/587H01M50/426H01M4/485H01M4/505H01M4/525H01M4/583
Inventor 李伟善温玉铖陈荟杨陈嘉威卢奕彤车艳霞
Owner SOUTH CHINA NORMAL UNIVERSITY
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