Blended electrodes were investigated to overcome problems of lithium-ion rechargeable batteries with manganese spinel as cathode materials. This blending technique has beneficial effects on prevention of capacity decline by storage or charge-discharge cycle at elevated temperature. LiNi 0.8 Co 0.2 O 2 is useful as an additive to prevent Mn dissolution from manganese spinel in electrolyte. Moreover, cell capacity is increased by the blending because LiNi 0.8 Co 0.2 O 2 has a higher capacity than manganese spinel. As a result, a cell with blended cathode can show high capacity equal to LiCoO 2 . The blending technique of anode materials was studied to improve capacity and cycle performance. Blended anode of flaky and spherical graphite shows high charge-discharge efficiency at high anode densities and good cycle performance at high temperature due to improved conductivity between graphite particles.