Pore-forming method for diaphragms of lithium ion batteries

A lithium-ion battery, membrane technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of difficult to achieve large-scale and efficient mass production, reduced energy density of cells, and high price, and achieves the realization of Mass production, simple realization, low cost effect

Active Publication Date: 2014-11-05
NINGDE AMPEREX TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because the former needs to add pore-forming agent to the slurry, which is a very sensitive metastable system, it will have a certain impact on the selection of slurry formulation and the pulping process; and if you want to make a highly efficient porous material with more pores on the surface and fewer pores in the inner layer. structure, this method requires the preparation of slurries with different concentrations of pore-forming agents and multi-layer coating to achieve, which is a very complicated process
The diaphragm punching method is mainly to create a specific hole structure in the diaphragm through mechanical / physical methods. During the implementation of this method, it will cause mechanical / physical damage to the active material in the diaphragm, resulting in a decrease in the energy density of the cell. reduce; and this method is difficult to achieve large-scale, efficient mass production in a short period of time, in addition, the diaphragm punching method also requires the use of expensive precision instruments and equipment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] 0.1 mol of benzoic acid powder was fully dissolved in 1 L of nitrogen-methylpyrrolidone (NMP) solvent to prepare a 0.1 mol / L pore-forming agent solution, and the viscosity of the pore-forming agent solution was 1 mPa·s. Take the coated graphite negative electrode diaphragm before cold pressing, and uniformly coat a layer of pore-forming agent solution on its surface by spraying. Because the viscosity of the pore-forming agent solution is very low, the penetration resistance of the membrane to the pore-forming agent solution is very small, and most of the pore-forming agent solution will penetrate into the bottom layer of the membrane. The membrane coated with the pore-forming agent solution is baked at 85°C for 10 minutes to fully volatilize the NMP, and at the same time, the benzoic acid solute recrystallizes and occupies a certain position in the pores at the bottom of the membrane. Then, the diaphragm implanted with benzoic acid crystals is cold-pressed; then the col...

Embodiment 2

[0031] Take 1 mol of oxalic acid powder and fully dissolve it in 1 L of pure water solvent to prepare a 1 mol / L pore-forming agent solution. The viscosity of the pore-forming agent solution is 100 mPa·s. Take the coated lithium cobalt oxide cathode diaphragm before cold pressing, and evenly coat a layer of pore-forming agent solution on its surface by brush coating. Because the viscosity of the pore-forming agent solution is moderate, the membrane has only an appropriate resistance to the penetration of the pore-forming agent solution, and the pore-forming agent solution will evenly penetrate into the inside of the membrane. The membrane coated with the pore-forming agent solution is baked at 100°C for 15 minutes to fully volatilize the water solvent, and at the same time the oxalic acid solute recrystallizes and occupies a certain position in the pores at the bottom of the membrane. Next, cold-press the diaphragm implanted with oxalic acid crystals; then vacuum-bake the cold-...

Embodiment 3

[0033] Take 10 mol of nanoball powder and fully dissolve it in 1 L of ethanol solvent to prepare a 10 mol / L pore-forming agent solution with a viscosity of 900 mPa·s. Take the coated lithium iron phosphate positive electrode diaphragm before cold pressing, and uniformly coat a layer of pore-forming agent solution on its surface by extrusion coating method. Because the viscosity of the pore-forming agent solution is high, the penetration resistance of the membrane to the pore-forming agent solution is very large, and only a small amount of the pore-forming agent solution can penetrate into the bottom layer of the membrane. The membrane coated with the pore-forming agent solution is baked at 45°C for 10 minutes to fully volatilize the ethanol, and at the same time, the solute of the pellet recrystallizes and occupies a certain position in the pores at the bottom of the membrane. Next, cold-press the diaphragm implanted with the nano-ball crystals; then vacuum-bake the cold-press...

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PUM

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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a pore-forming method for diaphragms of lithium ion batteries. The method comprises the following steps: fully dissolving a pore-forming agent into a solvent so as to prepare a pore-forming agent solution; uniformly coating the pore-forming agent solution on the surface of a to-be-cold-pressed diaphragm, and carrying out baking on the diaphragm at a temperature lower than the sublimation or decomposition temperature of the pore-forming agent, so that a solvent of the pore-forming agent solution is volatilized, and the pore-forming agent is recrystallized in the diaphragm; and carrying out cold pressing on the diaphragm, and then carrying out baking on the diaphragm at a temperature higher than the sublimation or decomposition temperature of the pore-forming agent, so that the pore-forming agent recrystallized in the diaphragm is sublimated or decomposed, thereby obtaining a porous diaphragm. According to the invention, through regulating the viscosity of the pore-forming agent solution, a diaphragm with adjustably-distributed pores can be obtained, and the regulating method is simple and flexible, and wide in applicable range; and particularly, according to the invention, an efficient gradient pore distribution structure that more pores are distributed on the surface layer of the diaphragm and less pores are distributed on the inner layer of the diaphragm can be realized just through selecting an appropriate viscosity of the pore-forming agent solution..

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a pore-forming method for a lithium-ion battery diaphragm. Background technique [0002] Since the large-scale commercialization of lithium-ion batteries, they have been widely used in portable electrical appliances such as laptops, cameras, and mobile communications due to their advantages of high energy density and high power density. However, with the continuous updating of the design of consumer electronic products and the widening of application requirements, the requirements for battery performance (such as fast charging and discharging performance, good low temperature performance) are also increasing. [0003] As known in the industry, the improvement of battery performance depends on the rapid conduction of two channels in the battery system: ion channels and electron channels. For the rapid conduction of ion channels, the key lies in the porou...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/139
CPCY02E60/122Y02E60/10
Inventor 李白清游从辉江辉方宏新张柏清
Owner NINGDE AMPEREX TECH
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