Lithium supplementing composite diaphragm and preparation method thereof

A composite diaphragm and lithium replenishment technology, applied in the field of lithium replenishment composite diaphragm and its preparation, can solve the problems of low initial charge and discharge efficiency of lithium ion batteries, decrease of reversible capacity of lithium ion batteries, consumption of active lithium ions, etc., so as to avoid thermal runaway. problems, improving rate performance and cycle performance, and the effect of increasing gram capacity

Pending Publication Date: 2021-01-26
SUNWODA ELECTRIC VEHICLE BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

However, at present, the commonly used polyolefin separator exhibits large thermal shrinkage at high temperatures, which causes the deformation of the separator and leads to direct contact between the positive and negative electrodes, causing short-circuit thermal runaway or even explosion.
[0003] In addition, during the initial charging process, the formation of SEI film on the negative electrode will consume part...

Method used

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  • Lithium supplementing composite diaphragm and preparation method thereof

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preparation example Construction

[0032] In another aspect, a method for preparing the above-mentioned lithium-supplementing composite separator is provided, comprising the steps of:

[0033] S1: Add the lithium-replenishing active material and the binder into the solvent, and mix uniformly in an environment with a humidity of less than 1% and a temperature of 15-30°C to obtain a lithium-replenishing slurry;

[0034] S2: Coating the lithium-replenishing slurry on the side of the base film facing the positive electrode, and drying at a temperature of 35-100° C., to prepare a lithium-replenishing composite membrane.

[0035] In the embodiment of the present invention, the solvent in step S1 is selected from one of water or N-methylpyrrolidone (NMP).

Embodiment 1

[0038] A lithium-replenishing composite diaphragm, which includes a polyethylene base film, the thickness of the base film is 9 μm, the side of the base film facing the positive electrode is coated with a lithium-replenishing layer, the thickness of the lithium-replenishing layer is 1.5 μm, and the lithium-replenishing layer includes lithium-replenishing active materials and binder, the lithium supplement active material is Li with a particle size of 100nm 2 TiO 3 , where Li 2 TiO 3 The mass percentage is 80%, the binder is sodium hydroxymethyl cellulose, and the mass percentage of sodium hydroxymethyl cellulose is 20%.

[0039] The preparation method of the above-mentioned lithium-supplementing composite diaphragm comprises the following steps:

[0040] S1: 200g of Li with a particle size of 100nm 2 TiO 3 Add 800g of water solvent and stir for 30min, then add 50g of hydroxymethylcellulose sodium and continue to stir for 2.5h, and mix evenly in an environment with a humid...

Embodiment 2

[0043] Based on Example 1, the only difference is that in Example 2, the lithium supplement active material is Li 4 SiO 4 .

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Abstract

The invention discloses a lithium supplementing composite diaphragm and a preparation method thereof. The lithium supplementing composite diaphragm comprises a base membrane, one side, facing a positive electrode, of the base membrane is coated with a lithium supplementing layer, the material of the lithium supplementing layer comprises a lithium supplementing active substance and a binder, and the lithium supplementing active substance is metal oxide lithium salt. The lithium supplementing active substance adopts the metal oxide lithium salt, so that the gram volume of the positive electrodematerial can be improved, the lithium ion transmission rate is increased, and the rate capability and the cycle performance of the lithium ion battery are improved; on the other hand, the mechanical property of the diaphragm can be effectively enhanced, the temperature resistance of the diaphragm is improved, and the safety performance of the lithium ion battery is enhanced; besides, compared witha traditional method that the surface of the positive electrode material is coated with the metal oxide lithium salt serving as the lithium supplementing active substance, the metal oxide lithium salt is applied to the diaphragm, the mass of the positive electrode material cannot be increased, and therefore reduction of the gram volume of the positive electrode material due to addition of the lithium supplementing active substance can be avoided.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a lithium-supplementing composite diaphragm and a preparation method thereof. Background technique [0002] Lithium-ion batteries are widely used in digital, electric vehicles, energy storage and other fields due to their excellent energy density, rate performance and long service life. Lithium-ion batteries are mainly composed of positive electrodes, negative electrodes, electrolytes, diaphragms, and battery casings, and rely on lithium ions to migrate and deintercalate between the positive and negative electrodes to provide energy during operation. The separator should not only block the direct contact between the positive and negative electrodes, but also provide a migration channel for lithium ions. Its design is directly related to the electrochemical performance and safety performance of lithium-ion batteries. But at present, the commonly used polyolefin sepa...

Claims

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Application Information

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IPC IPC(8): H01M50/449H01M50/411H01M50/431H01M50/403H01M10/0525
CPCH01M10/0525Y02E60/10
Inventor 张旭辉陈巍张耀
Owner SUNWODA ELECTRIC VEHICLE BATTERY CO LTD
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