| 摘要 |
PROBLEM TO BE SOLVED: To reduce mechanical strain, increase strength, and improve uniformity by heat treatment after a massive substance consisting of a metal oxide is pulverized and graded. SOLUTION: A metal oxide includes a lithium employed for a positive electrode of a lithium secondary battery and a tin or tungsten employed for a compound oxide of a transient metal and a negative electrode and the like. Average size of powder when these massive substances are pulverized is preferably 1 micron or more, and 20 microns or less. A metal oxide powder adjusted to this size distribution is changed to a substantially spherical powder by heat treatment. Thereby, decomposition of electrolyte caused in an active breakage face or separator breakage or the like decreases. Heat treatment is preferably performed in a high-temperature airflow in separated particle state. As a high- temperature airflow, mixed flow of hydrogen/oxygen is preferred. In addition, the temperature of heat treatment is 700 deg.C or more and 1,700 deg.C or less. After heat treatment, the more preferable size of the particles employed for an electrode is 3 microns or more to 15 microns or less. |
