Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery

A non-aqueous electrolyte, secondary battery technology, applied in secondary batteries, battery electrodes, circuits, etc., can solve problems such as lower battery charge and discharge efficiency

Inactive Publication Date: 2011-12-21
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the nonaqueous electrolyte decomposes, the charge and discharge efficiency of the battery decreases

Method used

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  • Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery
  • Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery
  • Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0071] (a) Preparation of negative electrode

[0072] Process (i)

[0073] First, carboxymethylcellulose (hereinafter referred to as CMC, molecular weight: 200,000, degree of etherification: 0.7) which is a water-soluble polymer was dissolved in water to obtain an aqueous solution having a CMC concentration of 0.7% by weight. The viscosity at 25° C. of an aqueous solution having a CMC concentration of 0.7% by weight was measured with a B-type viscometer and found to be 1.5 Pa·s. The natural graphite particles (the average particle size is 18 μm, the average circularity is 0.92, the specific surface area is 4.8m 2 / g) 100 parts by weight and 100 parts by weight of the CMC aqueous solution were mixed, and the mixture was stirred while controlling the temperature of the mixture to 25°C. Then, the mixture was dried at 80° C. for 5 hours to obtain a dry mixture. In the dry mixture, the amount of CMC was 0.7 parts by weight per 100 parts by weight of graphite particles.

[0074]...

Embodiment 2

[0117] A negative electrode was produced in the same manner as in Example 1, except that the dried coating film was rolled with a calender roll at a linear pressure of 40 kgf / cm in step (iii). A lithium ion secondary battery was fabricated in the same manner as in Example 1 except for using this negative electrode. The same evaluation as in Example 1 was performed on the negative electrode and the battery.

Embodiment 3

[0121] A negative electrode was fabricated in the same manner as in Example 1, except that the dried coating film was rolled with a calender roll at a linear pressure of 60 kgf / cm in step (iii). A lithium ion secondary battery was fabricated in the same manner as in Example 1 except for using this negative electrode. The same evaluation as in Example 1 was performed on the negative electrode and the battery.

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Abstract

The negative electrode for the non-aqueous electrolyte secondary battery includes a negative electrode core material and a negative electrode mixture layer attached to the negative electrode core material. The specific surface area of ​​the negative electrode mixture layer is 2.2-3m2 / g, and the bonding strength between the graphite particles coated with water-soluble polymer is more than 14kgf / cm2. A nonaqueous electrolyte secondary battery including this electrode can suppress decomposition of nonaqueous electrolyte components caused by the reaction between graphite particles and the nonaqueous electrolyte, and thus has excellent charge and discharge efficiency.

Description

technical field [0001] The present invention relates to a negative electrode for a non-aqueous electrolyte secondary battery containing graphite particles as an active material, and particularly to improvement of a negative electrode mixture layer. Background technique [0002] As a negative electrode of a nonaqueous electrolyte secondary battery typified by a lithium ion secondary battery, various materials can be used as an active material. In particular, graphite materials that can intercalate and detach lithium ions are the mainstream, and natural graphite, artificial graphite, graphitized mesocarbon particles, graphitized mesocarbon fibers, and the like have been used. [0003] For example, when graphite particles are used as the negative electrode active material, graphite particles and a binder are mixed in the presence of a predetermined dispersion medium to prepare negative electrode mixture slurry. In this case, generally, polyvinylidene fluoride (PVDF), polytetra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/133H01M4/1393H01M4/36H01M4/587H01M4/62
CPCY02E60/122H01M4/1393H01M4/62H01M10/0525H01M4/366H01M4/133H01M4/622Y02E60/10H01M4/583
Inventor 笠松真治平野畅宏宇贺治正弥
Owner PANASONIC CORP
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