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Evaluation method of stability of lithium-ion battery positive and negative electrode paste

A technology of lithium ion battery and evaluation method, which is applied in the field of evaluation of the stability of positive and negative electrode slurry of lithium ion battery, can solve the problems of slurry layering, battery performance impact, poor consistency of battery cells, etc., and achieves good reproducibility , Good practicability, accurate test effect

Active Publication Date: 2016-11-16
SPRINGPOWER TECHNOLOGY (SHENZHEN) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, battery slurry is a suspension system formed by mixing and stirring active materials, conductive agents, binders, and solvents. There are huge differences in the particle sizes of different substances in the slurry, and the affinity of the surface groups for solvents is also Not the same, in addition, there will be agglomeration between particles, which will lead to uneven dispersion of particles of different substances in the slurry, and the stability of the slurry will deteriorate
However, the slurry with poor stability will settle during the coating process, which will seriously cause the slurry to be delaminated, resulting in an unstable coating amount of the active material on the current collector, which will lead to poor consistency of the manufactured cells, and Battery performance is severely affected, so battery paste stability is critical to battery production
[0004] Patent CN101382489A evaluates the stability of the slurry by testing the difference in the backscattering intensity of the upper and lower layers of the slurry after centrifugation. Although this method is fast, the slurry needs to be centrifuged many times, and then a laser scattering instrument is used to measure the backscattering intensity. The measurement process is cumbersome. In addition, this test method has no standards for centrifugation speed and centrifugation time. When testing the stability of different slurries, the centrifugation conditions need to be reset, which is not conducive to the operation of employees in production.

Method used

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  • Evaluation method of stability of lithium-ion battery positive and negative electrode paste
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  • Evaluation method of stability of lithium-ion battery positive and negative electrode paste

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Weigh the positive active material lithium cobalt oxide (96% mass ratio, the same below), super conductive carbon black, and binder polyvinylidene fluoride, and use N-methylpyrrolidone as a solvent to prepare lithium cobalt oxide slurry according to the process design. . Take 250mL of fresh lithium cobalt oxide slurry and use the 5# rotor of the viscosity tester to test the viscosity of the slurry, set the rotation speed of the rotor to 5rpm, 10rpm, 20rpm, 30rpm, 50rpm, 60rpm in turn, record the viscosity value at each rotation speed, then Continue to set the rotational speed of the rotor to 60rpm, 50rpm, 30rpm, 20rpm, 10rpm, 5rpm, record the viscosity value at each rotational speed, and draw two viscosities according to the change of the viscosity value when the rotational speed changes from small to large and from large to small. The curve with the speed of rotation, the results are as follows figure 1 , figure 1 The middle dotted line is the change curve of viscosi...

Embodiment 2

[0031] Weigh the positive active material ternary material (96% mass ratio, the same below), super conductive carbon black, binder polyvinylidene fluoride, and use N-methylpyrrolidone as a solvent to prepare a ternary slurry according to the process design. Take 500mL of fresh slurry and use the 5# rotor of the viscosity tester to test the viscosity of the slurry, set the rotation speed of the rotor to 5rpm, 10rpm, 20rpm, 30rpm, 50rpm, 60rpm in turn, record the viscosity value at each rotation speed, and then continue to rotate the rotor. The rotational speed is set to 60rpm, 50rpm, 30rpm, 20rpm, 10rpm, 5rpm, record the viscosity value at each rotational speed, and draw two changes of viscosity with rotational speed according to the change of the viscosity value when the rotational speed changes from small to large and from large to small. curve, the result is as image 3 , image 3 The middle dotted line is the change curve of viscosity with rotational speed when the rotatio...

Embodiment 3

[0034] Weigh the negative electrode active material graphite (96% mass ratio, the same below), super conductive carbon black, sodium carboxymethyl cellulose and styrene-butadiene rubber, use deionized water as a solvent, and prepare graphite slurry according to the process design. Take 1000 mL of fresh graphite slurry and use the 5# rotor of the viscosity tester to test the viscosity of the slurry, set the rotation speed of the rotor to 5rpm, 10rpm, 20rpm, 30rpm, 50rpm, 60rpm in turn, record the viscosity value at each rotation speed, and then continue Set the rotational speed of the rotor to 60rpm, 50rpm, 30rpm, 20rpm, 10rpm, and 5rpm, record the viscosity value at each rotational speed, and draw two viscosity curves according to the change of the viscosity value when the rotational speed changes from small to large and from large to small. The change curve of the speed, the results are as follows Figure 5 , Figure 5 The middle dotted line is the change curve of viscosity ...

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Abstract

The invention discloses an evaluation method of the stability of lithium-ion battery positive and negative electrode paste. The method comprises the steps that viscosity variation in the process that the rotating speed changes from low to high and viscosity variation in the process that the rotating speed changed from high to low are tested respectively, and two curves of the paste viscosity changing along with the rotating speed are drawn respectively; the repeatability of the curves of the paste viscosity changing along with the rotating speed is analyzed, the stability of the positive and negative electrode paste is judged afterwards, when the repeatability of the two curves is good, it is shown that the stability of the positive electrode paste or the negative electrode paste is good, and when the repeatability of the two curves is poor, it is shown that the stability of the positive electrode paste or the negative electrode paste is poor. By means of the evaluation method of the stability of the lithium-ion battery positive and negative electrode paste, the stability of the paste can be judged very rapidly and easily, the reproducibility of the test is very good, the test is very accurate, the practicability is very good, and a very effective and practical method can be provided for stability evaluation of the lithium-ion battery positive and negative electrode paste.

Description

technical field [0001] The invention relates to the technical field of battery manufacturing, in particular to a method for evaluating the stability of positive and negative electrode slurry of a lithium ion battery. Background technique [0002] Lithium-ion batteries have the characteristics of high specific capacity, small self-discharge, wide operating temperature range, high voltage platform, long cycle life, no memory effect, and environmental friendliness. They have been widely used in mobile phones, notebook computers, power tools and other fields. And gradually promote in the field of electric vehicles. [0003] The first step in the production of lithium-ion batteries is to mix the positive and negative electrodes, and then coat them on the current collector for subsequent cell production. However, the battery slurry is a suspension system formed by mixing and stirring active materials, conductive agents, binders and solvents. There are huge differences in particle...

Claims

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Application Information

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IPC IPC(8): G01N11/14
CPCG01N11/14
Inventor 秦雪英张琦于立娟张西涛陈启多程君李文良
Owner SPRINGPOWER TECHNOLOGY (SHENZHEN) CO LTD
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