Carbonaceous material for negative electrodes of nonaqueous electrolyte secondary batteries, and method for producing same

Abstract

The purpose of the present invention is to provide: a carbonaceous material for negative electrodes of nonaqueous electrolyte secondary batteries, which uses a plant-derived organic material as a starting material, and from which alkali metals such as potassium element and alkaline earth metals such as calcium element are sufficiently removed by decalcification, so that the carbonaceous material has high purity and excellent discharge capacity and efficiency; a novel production method which is capable of efficiently mass-producing the carbonaceous material; and a lithium ion secondary battery which uses the carbonaceous material. The above-mentioned purpose can be achieved by a carbonaceous material for negative electrodes of nonaqueous electrolyte secondary batteries, which is obtained by carbonizing a plant-derived organic material, and which has an atomic ratio of hydrogen atoms to carbon atoms (H / C) as determined by elemental analysis of 0.1 or less, an average particle diameter (Dv50) of 2-50 mum, an average interplanar spacing of the (002) plane as determined by a powder X-ray diffraction method of 0.365-0.400 nm, a potassium element content of 0.5% by mass or less and a calcium element content of 0.02% by mass or less.

Description

technical field [0001] The invention relates to a carbonaceous material for the negative pole of a non-aqueous electrolyte secondary battery and a manufacturing method thereof. Background technique [0002] In recent years, people have become more concerned about environmental issues, so the industry is researching the installation of large-scale lithium-ion secondary batteries with high energy density and excellent output characteristics in electric vehicles. When used in small portable devices such as mobile phones and notebook computers, the capacity per unit volume becomes particularly important, so graphite materials with relatively high density have been mainly used as negative electrode active materials. However, when a lithium-ion secondary battery for vehicles is used, it is difficult to replace it halfway because of its bulkiness and high price. Therefore, it is required to have at least the same durability as that of an automobile, and to be able to realize a lif...

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Problems solved by technology

[0029] In addition, we know that the average layer spacing d of the carbonaceous material derived from plants is 002 Shorter than general non-graphitizable carbon, the expansion and contraction of the crystal accompanying lithium doping and dedoping is large, so there is a problem that the cycle characteristics are low especially at high temperatures

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