Non-aqueous electrolyte secondary battery negative electrode material, making method, lithium ion secondary battery, and electrochemical capacitor

Abstract

A negative electrode material comprises a conductive powder of particles of a lithium ion-occluding and releasing material coated on their surface with a graphite coating. The graphite coating, on Raman spectroscopy analysis, develops broad peaks having an intensity I 1330 and I 1580 at 1330 cm -1 and 1580 cm -1 Raman shift, an intensity ratio I 1330 / I 1580 being 1.5 < I 1330 / I 1580 < 3.0. Using the negative electrode material, a lithium ion secondary battery having a high capacity and improved cycle performance can be manufactured.

Description

technical field [0001] The present invention relates to a negative electrode material for a nonaqueous electrolyte secondary battery, which exhibits high charge / discharge capacity and satisfactory cycle performance when used as a negative electrode active material in a lithium ion secondary battery, and also The invention relates to a preparation method of the negative electrode material of the above-mentioned non-aqueous electrolyte secondary battery, a lithium ion secondary battery and an electrochemical capacitor. Background technique [0002] With the recent remarkable development of portable electronic devices, communication devices, etc., there is a strong demand for high energy density secondary batteries from the viewpoints of economy, size, and weight reduction. A prior art method of increasing secondary battery capacity is to use oxides as negative electrode materials, such as oxides of V, Si, B, Zr, Sn, etc. or their composite oxides (see JP-A5-174818 and JP-A6-0...

AI Technical Summary

Problems solved by technology

Regarding the technique of imparting conductivity to the negative electrode material, JP-A2000-243396 encountered a problem that solid-solid fusion adhesion could not form a uniform carbon coating, resulting in insufficient conductivity

The method of JP-A 2000-215887 is capable of forming a uniform carbon coating, but as a result, the silicon-based negative electrode material undergoes excessive expansion and contraction when absorbing and desorbing lithium ions, and as a result cannot be practically implemented

Due to the decrease in cycle performance, and the charge / discharge capacity must be limited to prevent this deterioration in cycle performance

In JP-A 2002-42806, although the improvement in the cycle performance is considerable, as the charge / discharge cycle is repeated, because of the precipitation of silicon crystallites, the insufficient structure of the carbon coating, and the inconsistency between the carbon coating and the substrate Fully fused, so the capacity gradually decreases and drops suddenly after a certain number of charge / discharge cycles

Therefore, this method is not sufficient for use in secondary batteries

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