NEGATIVE ELECTRODE MATERIAL FOR LITHIUM SECONDARY BATTERY, LITHIUM SECONDARY BATTERY AND CHARGING METHOD FOR LITHIUM SECONDARY BATTERY

PROBLEM TO BE SOLVED: To prevent the destruction of a negative electrode by pulverization and to improve the discharge capacity, safety and cycle characteristic of a battery by covering the surfaces of particle nuclei of a metal or a semimetal capable of forming a lithium alloy with a carbon layer. SOLUTION: Various synthetic resin, tar or pitch covering particle nuclei is infusibility-processed then carbonized at a high temperature to form this negative electrode material, and the cover carbon suppresses the volume expansion of the particle nuclei caused by the alloying of lithium. Silicon which has a large lithium incorporation quantity per unit weight, is nonflammable and has the melting point and boiling point above the cover processing temperature of carbon is suitable for the particle nuclei. The average grain size of the particle nuclei is set to 0.1-50 μm, volume expansion and an increase of the cover carbon quantity are suppressed, and the specific surface area of the negative electrode material is preferably set to 5 m2/g or below to unify the cover. The carbon quantity in the negative electrode material is set to 5-50 wt.% for a complete cover and the prevention of discharge capacity reduction and inter-particle fusion, and the cover is applied by the chemical vapor deposition processing method for homogeneity and the prevention of inter-particle fusion.