| 摘要 |
PURPOSE:To extend the cycle life of a secondary battery and to eliminate the possibility of the battery being broken even with a rise in battery temperature by using binders of two kinds or more for a negative electrode each of which contains polyimide acid when the secondary battery is constituted of a positive electrode composed chiefly of a lithium-containing composite oxide, a negative electrode composed chiefly of a carbonaceous material, and an organic electrolyte. CONSTITUTION:Mixed binders of two kinds or more, each containing at least polyamide acid, are used in place of fluororesin which is previously used as a binder, so as to enhance the binding property of carbon powders to one another and to enhance the binding property of the carbon powders and a core; i.e., during heat treatments of electrodes the polyamide acid is dehydrated and condensed into a polyimide to bind the carbon powders together, and at the same time the polyamide acid is reacted with the core so that the binding property of the powders to the core is also improved. The amount of polyamide acid is 0.3 parts by weight or more and 67.0 parts by weight or less for the mixed binders. Then peeling and dropping of the carbon powders from the core can be avoided even if the cycle of charge and discharge is repeated. |
