Synthesis and electrochemical performance of LiNi_(0.7)Co_(0.15)Mn_(0.15)O_2 as gradient cathode material for lithium batteries

摘要

LiNi_(0.7)Co_(0.15)Mn_(0.15)O_2 as a cathode material for lithium batteries was synthesized by mixing hydroxide co-precipitated precursors with 5% excess LiOH·H_2O. Its structural and electrochemical properties were investigated using X-ray diffractometry, scanning electron microscopy, galvanostatic charge-discharge test, and electrochemical impedance spectroscopy. The results indicated that well-ordering layered LiNi_(0.7)Co_(0.15)Mn_(0.15)O_2 cathode materials were successfully prepared in air at 750, 800, and 850℃ with α-NaFeO_2 typical crystal. The results of charge-discharge test demonstrated that the gradient cathode material sintered at 850 C exhibited the best electrochemical performance with the initial discharge capacity of 164 mA h g~(-1) at 0.2 C and lower electrochemical impedance. Nickel has low price. LiNiO_2 cathode materials have high specific capacity, their theoretical capacity is 274 mA h g~(-1) and with low self-discharge rate. So the Ni, Co, Mn ternary layer-structural compounds with high Ni content are showing to be promising cathode materials for lithium batteries. The techniques and research results in this paper are utilizable for the study of this kind of lithium battery materials.