| 摘要 |
PURPOSE: To make continuous cycle use possible with large charge/discharge capacity maintained by containing a current collector and expanded graphite with an impurity content of a specified value or less or a crushed material of a compressed molding of expanded graphite to be integrated to the current collector in a negative electrode for a lithium battery. CONSTITUTION: Concentrated sulfuric acid and hydrogen peroxide are added to flake natural graphite to produce graphite intercalation compound, the graphite intercalation compound is dried and heated to produce 200-fold expanded graphite. The expanded graphite is compressed with a roll, then crushed with a jet mill so as to have a mean particle size of 10μm, purifying treatment is conducted in a non-oxidizing atmosphere furnace to reduce the impurity content to 20000ppm or less, preferably to 10ppm or less. The crushed material is kneaded with cetylene propylene terpolymer dissolved in xylene, the kneaded material is applied to a 20μm-thick copper foil, dried, then they are integrally compressed to form a negative electrode. Evaluation is conducted in such a way that the negative electrode serving as a specimen electrode 3 is combined with a separator 4 and a counter electrode 5, they are put into a glass cell 1, an electrolyte is filled, and a reference electrode 6 is arranged. |
