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Separator for lithium ion battery and preparation method of separator

A lithium-ion battery and diaphragm technology, which is applied to battery components, separators/films/diaphragms/spacers, circuits, etc., can solve problems affecting battery performance, increased diaphragm thickness, and low surface energy. Achieve precise control of coating thickness, improve battery performance, and lower process temperature

Inactive Publication Date: 2015-02-25
XINXIANG ZHONGKE SCI&TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the inherent characteristics of polyolefin polymers, it affects its performance in batteries, and even hinders its application in some fields.
[0003] The disadvantages of polyolefin battery separators are mainly manifested in: (1) low surface energy and poor hydrophilicity; resulting in poor wettability between polyolefin separators and highly polar electrolytes, and poor liquid retention capacity, thus affecting battery performance
(2) Poor thermal stability, prone to thermal shrinkage; the battery will emit a lot of heat when charging and discharging with high current, and the battery temperature will remain at a relatively high level
However, the low thermal stability of the polyolefin separator leads to a large thermal shrinkage at high temperature, which increases the risk of short circuit in the battery.
(3) Insufficient electrochemical stability; although the polyolefin separator has good stability, it still cannot fully meet the requirements of the battery under the trend of high voltage and high capacity of the battery, and yellowing and mechanical properties will appear after long-term use. Reduced energy phenomenon, which in turn affects the service life of the battery
But the disadvantage is that the thickness of the diaphragm is increased more, which runs counter to the current direction of high capacity and miniaturization of batteries.
Moreover, the coating layer only exists on the outer surface of the diaphragm, and does not improve the inner wall of the microporous structure.

Method used

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  • Separator for lithium ion battery and preparation method of separator
  • Separator for lithium ion battery and preparation method of separator
  • Separator for lithium ion battery and preparation method of separator

Examples

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Effect test

Embodiment 1

[0034] A separator for lithium-ion batteries, such as figure 1 As shown, it includes a polymer microporous membrane substrate, the surface of the substrate and the inner wall of the micropore channel are covered with a nano-oxide layer, wherein the substrate is polypropylene, the thickness of the substrate is 20 μm, the porosity is 40%, and the nano-oxide layer is The material layer is an aluminum oxide layer. The aluminum oxide layer has a thickness of 10-20 nm.

[0035] Its preparation method comprises the following steps:

[0036] (1) The biaxially stretched polypropylene microporous membrane substrate with a thickness of 20 μm and a porosity of 40% was first treated with a 3mol / L nitric acid solution for 10 minutes, and then soaked in a 1mol / L sodium hydroxide solution for 10 minutes. Wash with deionized water, then bake at 50°C for 1h;

[0037] (2) Put the microporous membrane obtained in step (1) into the cavity of the atomic layer deposition instrument, vacuumize an...

Embodiment 2

[0060] A separator for a lithium ion battery, comprising a polymer microporous film base material, the surface of the base material and the inner wall of the micropore channel are covered with nano-sized oxygen

[0061] The compound layer, wherein the substrate is polyethylene, the thickness of the substrate is 5 μm, the porosity is 30%, and the nano-oxide layer is an alumina layer. The aluminum oxide layer has a thickness of 10-20 nm.

[0062] Its preparation method comprises the following steps:

[0063] (1) The biaxially oriented polyethylene microporous membrane substrate with a thickness of 5 μm and a porosity of 30% was first treated with a 3mol / L nitric acid solution for 1min, and then soaked in a 1mol / L sodium hydroxide solution for 1min. Wash with deionized water, then bake at 40°C for 3h;

[0064] (2) Place the microporous membrane obtained in step (1) in the cavity of the atomic layer deposition instrument, vacuumize and heat to 100°C for 1 min.

[0065] (3) Introd...

Embodiment 3

[0072] A separator for a lithium ion battery, comprising a polymer microporous film base material, the surface of the base material and the inner wall of the micropore channel are covered with nano-sized oxygen

[0073] The compound layer, wherein the substrate is polyvinylidene chloride, the thickness of the substrate is 60 μm, the porosity is 60%, and the nano-oxide layer is an alumina layer. The aluminum oxide layer has a thickness of 80-100 nm.

[0074] Its preparation method comprises the following steps:

[0075] (1) The biaxially stretched polyvinylidene chloride microporous membrane substrate with a thickness of 60 μm and a porosity of 60% was first treated with a 3mol / L nitric acid solution for 15 minutes, and then soaked in a 1mol / L sodium hydroxide solution for 10 minutes Finally, wash with deionized water, and then bake at 80°C for 0.5h;

[0076] (2) Put the microporous membrane obtained in step (1) into the chamber of the atomic layer deposition instrument, vacu...

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Abstract

The invention discloses a separator for a lithium ion battery and belongs to the technical field of lithium ion batteries. The separator comprises a polymer microporous film substrate, wherein the surface of the substrate and the internal wall of a micropore duct of the substrate are coated with nano-oxide layers. The preparation method comprises the following steps: (1) performing oxidation treatment on the polymer microporous film with an acid solution, then washing the film successively with an alkali solution and deionized water and drying the film; (2) putting the film on an atomic layer deposition apparatus or a continuous atomic layer deposition device, then vacuumizing, heating to 50-100 DEG C and keeping for 1-30min; (3) introducing trimethylaluminum as a first precursor; (4) adding nitrogen or inert gas for purging; (5) introducing a second precursor; (6) adding nitrogen or inert gas for purging; (7) repeating steps (3)-(6); and (8) performing heat setting treatment. The separator disclosed by the invention is small in thickness and heat shrinkage, and is good in wetting property with electrolyte. The preparation process temperature is low, a formed coating is dense, and the thickness of the coating can be precisely controlled.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a separator for lithium ion batteries and a preparation method thereof. Background technique [0002] At present, in the field of batteries, polyolefin microporous membranes are usually used as separators for blocking positive and negative electrodes. For example, lithium-ion battery separators commonly include polypropylene (PP) microporous membranes and polyethylene (PE) microporous membranes. However, due to the inherent characteristics of polyolefin polymers, its performance in batteries is affected, and even its application in some fields is hindered. [0003] The main disadvantages of polyolefin battery separators are: (1) Low surface energy and poor hydrophilicity; resulting in poor wettability between polyolefin separators and highly polar electrolytes, and poor liquid retention capacity, thus affecting battery performance. (2) Poor therm...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M2/18H01M50/403H01M50/443H01M50/463H01M50/491
CPCH01M50/403H01M50/409H01M50/463Y02E60/10
Inventor 申向宇荆正军王向东杨邵萍张茹
Owner XINXIANG ZHONGKE SCI&TECH
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