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Method for improving hardness of lithium ion cell

A lithium-ion battery and hardness technology, applied in the field of lithium-ion batteries, can solve the problems of poor electrochemical performance of lithium-ion batteries, loss of battery capacity, increase in hardness of battery cells, etc. effect of speed

Active Publication Date: 2014-08-27
NINGDE AMPEREX TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] There are two main methods for improving the hardness of lithium-ion batteries: one is to heat and cold-press the battery cells before formation, and then place them in fixtures for high-temperature and high-pressure baking after formation and capacity to improve the hardness of the batteries. The purpose of hardness, due to the high temperature and high pressure baking operation, will lead to the loss of battery capacity
The other is to increase the hardness of the cell by coating polyvinylidene fluoride (PVDF) on the diaphragm. This method will cause the electrochemical performance of lithium-ion batteries to deteriorate due to the coating of polyvinylidene fluoride on the diaphragm.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Preparation of the cathode sheet: spinel lithium manganese oxide (LiMnO 2 ), the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) are added to the solvent nitrogen-methylpyrrolidone (NMP) according to the mass ratio of 94:3:3, and stirred and dispersed using a high-speed mixer to form a uniform positive electrode slurry. This slurry is coated on the aluminum foil current collector, and the solvent is dried. After drying, the positive electrode coating weight per unit area is 20.13mg / cm 2 , and then compact the pole piece, the density of the coating after compaction is about 3.0g / cm 3 .

[0037] Preparation of the anode sheet: the negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR, emulsion, about 50% solid content, 2.5 is the weight ratio of dry matter) and thickener carboxymethyl fiber Add plain sodium (CMC) into the solvent water at a mass ratio of 94.5:1.5:2:2...

Embodiment 2

[0045] Different from Example 1 is the preparation of lithium ion battery:

[0046]Step 1: Assemble the cathode sheet, anode sheet, and diaphragm into a battery cell through the lamination process, then put the battery cell into a packaging bag, inject the electrolyte solution after baking, and let it stand still. Batteries;

[0047] Step 2, place the fully soaked cells to be formed in the formation fixture, apply pressure to the surface of the cells through the fixture, the pressure is 0.1 MPa, and then pre-bake the cells at a temperature of 120°C for 1 min;

[0048] Step 3: Place the pre-baked formation jig that is to be formed into a battery cell first in the formation machine for formation, the formation temperature is 25°C, the formation current is 0.02C ("C" is the theoretical capacity of the battery cell), and the formation time is After 10 minutes, the formation cut-off potential was 3.0V. Then put it in the charge-discharge test machine to perform charge / discharge a...

Embodiment 3

[0052] Different from Example 1 is the preparation of lithium ion battery:

[0053] Step 1: Assemble the cathode sheet, anode sheet, and diaphragm into a battery cell through the lamination process, then put the battery cell into a packaging bag, inject the electrolyte solution after baking, and let it stand still. Batteries;

[0054] Step 2, place the fully soaked cells to be formed in the formation fixture, apply pressure to the surface of the cells through the fixture, the pressure is 2.0 MPa, and then pre-bake the cells at a temperature of 30°C for 100 minutes;

[0055] Step 3: Place the pre-baked formation jig to be formed in the formation machine first, the formation temperature is 100°C, the formation current is 0.02C ("C" is the theoretical capacity of the battery), and the formation time is After 10 minutes, the formation cut-off potential was 3.0V. Then put it in the charge-discharge test machine to perform charge / discharge and discharge / charge operations in sequen...

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Abstract

The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a method for improving the hardness of lithium-ion batteries through rapid formation. The purpose of cell polarization is to achieve rapid formation of large currents, and finally to adjust the formation cut-off potential to prepare lithium-ion batteries with higher hardness. Compared with the prior art, this method has the following advantages: because the high-temperature clamping and baking shaping after formation is canceled, the capacity of the prepared battery cell is higher; the battery cell is always subjected to constant (or variable) pressure during charging and discharging. Therefore, the polarization during charging and discharging is smaller, and the capacity consistency of the prepared cells is better; because different temperatures and SOC cut-off methods are used for formation, the prepared cells not only have excellent performance, but also have higher hardness.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, in particular to a method for improving the hardness of lithium-ion batteries through rapid formation. Background technique [0002] As the most representative energy storage device in the field of new energy, lithium-ion batteries occupy an irreplaceable position in power supply devices for mobile electronic products. As mobile electronic products become lighter and thinner, the thickness of lithium-ion batteries is getting thinner and thinner. From the perspective of safety, the requirements for the hardness of lithium-ion batteries are also getting higher and higher. At the same time, the production of batteries must also be taken into account. efficiency. How to realize the preparation of lithium-ion batteries with high hardness in a very short period of time is particularly important. [0003] There are two main methods for improving the hardness of lithium-ion batteries: one...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/058
CPCY02E60/10Y02P70/50
Inventor 李聪张柏清方宏新游从辉徐延杰
Owner NINGDE AMPEREX TECH
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