Ta doping and LiTaO3 coating to improve the electrochemical performance of LiNi0.925Co0.03Mn0.045O2 cathode material for lithium ion batteries

Abstract

LiNixCoyMnzO2(x ≥ 0.6, x + y + z = 1) is considered as one of the most potential cathode materials due to its high specific capacity, low cost, low toxicity and environmental friendliness. However, the internal structure and surface structure of LiNi0.925Co0.03Mn0.045O2 Ni-rich layered cathode are unstable during the electrochemical cycle. Moreover, the strategy of single doping or coating cannot comprehensively and effectively solve these problems. Herein, Ta doped and LiTaO3 coated LiNi0.925Co0.03Mn0.045O2 were successfully prepared, in which Ta2O5 reacting with surface residual alkali by solid-state reaction at high temperature. Electrochemical experimental results show that the Ta doped and LiTaO3 coated LiNi0.925Co0.03Mn0.045O2 has higher electrochemical stability, and the capacity retention of 100 cycles at 1C rate and 2.8 V–4.3 V voltage range is 87.61%, while it is 78.15% for bare material. In addition, the rate capacity under the cut-off voltage of 4.3 V has also been improved, and the discharge specific capacities under 5C are 170.05 and 179.5 mAh/g for bare material and Ta doped and LiTaO3 coated LiNi0.925Co0.03Mn0.045O2, respectively. Therefore, the synergistic effect of Ta doping and LiTaO3 coating can effectively improve the electrochemical performance of cathode materials. This method has certain reference significance for other lithium ion layered cathode materials.