Structure and Charge Regulation Strategy Enabling Superior Cycling Stability of Ni-Rich Cathode Materials
Chenrui Zeng, Fengxia Fan, Ruixin Zheng, Xinxiang Wang, Guilei Tian, Sheng Liu, Pengfei Liu, Chuan Wang, Shuhan Wang, Chaozhu Shu
Abstract
Ni-rich layered oxides LiNi x Co y Mn 1– x – y O 2 (NCMs, x > 0.8) are the most promising cathode candidates for Li-ion batteries because of their superior specific capacity and cost affordability. Unfortunately, NCMs suffer from a series of formidable challenges such as structural instability and incompatibility with commonly used electrolytes, which seriously hamper their practical applications on a large scale. Herein, the Al/Ta codoping modification strategy is proposed to improve the performance of the LiNi 0.83 Co 0.1 Mn 0.07 O 2 cathode, and the as-prepared Al/Ta-modified LiNi 0.83 Co 0.1 Mn 0.07 O 2 delivers exceptional cycling stability with a capacity retention of 97.4% after 150 cycles at 1C and an excellent rate performance with a high capacity of 143.2 mAh g –1 even at 3C. Based on the experimental study, it is found that the structural stability of NCM is strengthened due to the regulated coordination of oxygen by introducing a robust Ta–O covalent bond, which prevents the layered structure from collapsing. Moreover, the reconstructed rock-salt-like surface is capable of effectively inhibiting interfacial side reactions as well as the overgrowth of the cathode–electrolyte interface. Theoretically, the energy of Li/Ni mixing is significantly increased with the introduction of Al and Ta elements in Al/Ta codoped NCM, leading to inhibited adverse phase transition during cycling. A feasible pathway for designing and developing advanced Ni-rich cathode materials for Li-ion batteries is provided in this work.