Syntheses and electrochemical properties of layered Li_(0.95)Na_(0.05)Ni_⅓Co_⅓Mn_⅓O_2 and LiNi_⅓Co_⅓Mn_⅓O_2

摘要

Phase pure Li_(0.95)Na_(0.05)Ni_⅓Co_⅓Mn_⅓O_2 and LiNi_⅓Co_⅓Mn_⅓O_2 have been synthesized by calcination of co-precipitated precursors. Scanning electron microscopy shows that the powders are aggregated microplates sized between 100 nm and 300 nm in diameter and 50 nm in thickness. Electrochemical tests show that the Li_(0.95)Na_(0.05)Ni_⅓Co_⅓Mn_⅓O_2 discharges initially a much higher capacity under a current density of 27 mA g~(-1) (250.5 mAh g~(-1)) than LiNi_⅓Co_⅓Mn_⅓O_2 (155.4 mAh g~(-1)). The discharge capacity at the 70th cycle is 134.8 mAh g~(-1) under a current density of 135 mA g~(-1) and it increases to 143.1 mAh g~(-1) after the test cell has been standing still for 3 months. The latter cell exhibits better cycle performance with capacity retention of 99.02% after 110 cycles at different current densities, therefore, Li_(0.95)Na_(0.05)Ni_⅓Co_⅓Mn_⅓O_2 is capable of self-repairing.