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Porous diaphragm, preparation method of porous diaphragm as well as lithium ion battery

A technology of porous diaphragm and pore size, which is applied in the direction of secondary batteries, battery pack components, circuits, etc., can solve the problems of poor wettability of porous diaphragm and unfavorable lithium battery cycle performance, etc., achieve good heat resistance, avoid battery explosion and burning effect

Active Publication Date: 2014-09-17
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the wettability of the porous separator is poor, which is not conducive to the cycle performance of lithium batteries.

Method used

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  • Porous diaphragm, preparation method of porous diaphragm as well as lithium ion battery
  • Porous diaphragm, preparation method of porous diaphragm as well as lithium ion battery

Examples

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preparation example Construction

[0037] The present invention also provides a preparation method of a porous diaphragm, comprising the following steps:

[0038] A) Dissolving the heat-resistant polymer in an organic solvent to obtain a casting solution, the heat-resistant polymer includes polyphosphazene, polysulfone, polyethersulfone, polyetheretherketone, polyetheramide and polyacrylonitrile one or more of them;

[0039] B) extruding the casting solution obtained in step A) to obtain a liquid precursor film;

[0040]C) immersing the liquid precursor film obtained in step B) into a non-solvent for curing to obtain a solid precursor film;

[0041] D) Drying the solid precursor film in step C) to obtain a porous diaphragm.

[0042] In the invention, the heat-resistant polymer is dissolved in an organic solvent to obtain a casting liquid. In order to make the resulting porous diaphragm have better mechanical strength, the present invention preferably uses a cross-linking agent to modify the heat-resistant po...

Embodiment 1

[0082] Dissolving 45g of polyethersulfone in 55g of diisobutyl phthalate to prepare a casting solution with a solid content of 45%;

[0083] Extrude the casting solution through a slit to obtain a liquid precursor film; pull the liquid precursor film through an air gap of 5 cm and then immerse it in ethanol for 3.5 hours to obtain a solid precursor film;

[0084] Then adopt 1 roller to wind up, obtain diaphragm semi-finished product, the ratio of the rotating speed of roller and extrusion speed is 1.1:1;

[0085] The solid precursor film was placed at 20°C for 4 hours; then at 45°C for 1 hour; finally at 65°C for 24 hours to obtain a porous separator. The Gurley value of the obtained porous membrane is 300sec·100mL -1 , the surface pore diameter is 0.07 μm, the internal pore diameter is 0.5 μm, and the porosity is 44%.

[0086] The present invention tests the air permeability of the porous diaphragm provided in this embodiment according to the above-mentioned technical solut...

Embodiment 2

[0092] 35g of polyacrylonitrile was dissolved in 65g of bis(2-ethylhexyl) phthalate to prepare a casting solution with a solid content of 35%;

[0093] Extruding the casting solution through a slit to obtain a liquid precursor film; pulling the liquid precursor film through an air gap of 25 cm and then immersing it in ethanol for 0.5 hours to obtain a solid precursor film;

[0094] Then adopt 1 roller to wind up, obtain diaphragm semi-finished product, the ratio of the rotating speed of roller and extrusion speed is 1.4:1;

[0095] The solid precursor film was placed at 30°C for 2 hours; then at 35°C for 4 hours; finally at 55°C for 15 hours to obtain a porous separator. The Gurley value of the obtained porous membrane is 200sec·100mL -1 , the surface pore diameter is 0.15 μm, the internal pore diameter is 1.5 μm, and the porosity is 62%.

[0096] The present invention tests the air permeability of the porous diaphragm provided in this embodiment according to the above-menti...

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Abstract

The invention provides a porous diaphragm. The porous diaphragm is made of a heat-resisting polymer, wherein the heat-resisting polymer comprising one or more of polyphosphazene, polysulfone, polyether sulfone, polyether ether ketone, polyether amide and polyacrylonitrile. The porous diaphragm provided by the invention has relatively high surface energy, so that the porous diaphragm has favorable wettability, and has good interaction with electrolyte, so that the liquid retention rate of the lithium ion battery diaphragm is improved, and the development of the battery cycle performance is facilitated. The invention also provides a preparation method of the porous diaphragm. According to the preparation method provided by the invention, the heat-resisting polymer acts as a raw material, and holes are formed by a method of phase conversion and pore forming, so that the porous diaphragm has relatively high surface energy and excellent heat-resisting performance, and meanwhile the hole wall of the diaphragm has curvature, so that the micro short circuit of the lithium ion battery and self discharge can be avoided, and the liquid leakage phenomenon can be relieved. The invention also provides the lithium ion battery, and the porous diaphragm provided by the invention is a battery diaphragm.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a porous diaphragm, a preparation method thereof and a lithium ion battery. Background technique [0002] Lithium-ion batteries are currently the representative of high-performance batteries. Because lithium-ion batteries have the highest volume specific energy and mass specific energy, and will not pollute the environment, their application range continues to expand, and they are now widely used in portable electronic devices, Power tools, electric vehicles, energy storage power stations and other fields. With the increasingly widespread application of lithium-ion batteries, the prior art also puts forward higher requirements on the comprehensive performance of lithium-ion batteries. [0003] A lithium-ion battery is mainly composed of a positive electrode, a negative electrode, a battery separator, an organic electrolyte and a battery casing. The batt...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M50/403H01M50/417
CPCH01M10/0525H01M50/403H01M50/411Y02E60/10
Inventor 石俊黎夏永高刘兆平
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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