| 摘要 |
PURPOSE:To reduce a capacity deterioration rate due to electric charging/discharging of a battery and realize an excellent cycle characteristic by restraining decomposition of a non-aqueous electrolyte at the surface of a carbon material by the effect of a coating film made of triester phosphate produced at the surface of the carbon material. CONSTITUTION:A non-aqueous electrolyte secondary battery comprises a positive electrode, and a negative electrode made of a carbon material having 3.37Angstrom or less of a (d) value (d002) at a grid surface (002), and a non-aqueous electrolyte. If the carbon material is composed of a high capacity material having such high crystallinity as a (d) value less than 3.37Angstrom , it is confirmed that decomposition deterioration of the non-aqueous electrolyte is prominent. The non-aqueous electrolyte includes 0.1-10wt% of triester phosphate expressed by the formula I (wherein R<1>, R<2> and R<3> represent an alkyl or phenyl group having C1-4 individual). If the included quantity is less than 0.1wt.%, a coating film having a sufficient thickness cannot be formed so that decomposition at the surface of the carbon material cannot be restrained. If the quantity exceeds 10wt.%, a coating film becomes excessively thick so that permeability of a lithium ion is deteriorated, thus resulting in an increase in reaction resistance of an electrode plate and reduction cycle characteristic. |
