Ta doping and LiTaO₃ coating to improve the electrochemical performance of LiNi_0.925Co_0.03Mn_0.045O₂ cathode material for lithium ion batteries

LiNi_xCo_yMn_zO₂(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 LiNi_0.925Co_0.03Mn_0.045O₂ 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 LiNi_0.925Co_0.03Mn_0.045O₂ 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 LiNi_0.925Co_0.03Mn_0.045O₂ 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 LiNi_0.925Co_0.03Mn_0.045O₂, 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.