Huang Wei, Li Wenjin, Gao Min, Wang Xiaodan, Wang Jiantao, Zhuang Weidong
National Power Battery Innovation Center, Grinm Group Corporation Limited, Beijing 100088, China.
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China.
ACS Appl Mater Interfaces. 2022 Sep 28;14(38):43085-43094. doi: 10.1021/acsami.2c07453. Epub 2022 Sep 15.
Structural degradation and surface chemical instability are dominant issues of Ni-rich layered cathodes, which trigger capacity fading and safety concerns, hindering the extensive application of Ni-rich cathodes toward high-energy, long-life lithium-ion batteries. Here, by combining trace Ta doping and an ultrathin Zr-Y mixed oxide coating, an integrated modification strategy significantly improves the cycling and thermal stability of Ni-rich LiNiCoAlO (NCA) cathodes. The integrated modified Ni-rich cathode provides an unprecedented comprehensive performance with a high discharge capacity of 212.2 mA h g at 0.1 , an 88.6% cycling retention after 500 cycles at 1 , and a high exothermic peak temperature of 261 °C compared with the pristine NCA cathode (67.4% capacity retention for 500 cycles and 221 °C for the exothermic peak). Further mechanism studies illustrate that a dual-structural surface constructed of a rock salt surface induced by Ta doping and ultrathin Zr-Y mixed oxide coating jointly suppresses surface side reactions between cathodes and electrolytes. Moreover, trace Ta doping in the bulk stabilizes the bulk structure and prevents mechanical cracks. This study highlights the importance of comprehensive modification of the bulk and surface for improving the electrochemical performance and provides a potential optimizing strategy for the commercialization of high-capacity Ni-rich cathode materials.
结构退化和表面化学不稳定性是富镍层状正极的主要问题，这些问题会引发容量衰减和安全隐患，阻碍富镍正极在高能量、长寿命锂离子电池中的广泛应用。在此，通过结合微量钽掺杂和超薄锆 - 钇混合氧化物涂层，一种集成改性策略显著提高了富镍LiNiCoAlO（NCA）正极的循环稳定性和热稳定性。集成改性的富镍正极展现出前所未有的综合性能，在0.1 C下具有212.2 mA h g的高放电容量，在1 C下500次循环后循环保持率为88.6%，与原始NCA正极相比（500次循环容量保持率为67.4%，放热峰值温度为221 °C），放热峰值温度高达261 °C。进一步的机理研究表明，由钽掺杂诱导的岩盐表面和超薄锆 - 钇混合氧化物涂层共同构建的双结构表面抑制了正极与电解质之间的表面副反应。此外，体相中微量钽掺杂稳定了体相结构并防止机械裂纹。这项研究突出了对体相和表面进行综合改性以提高电化学性能的重要性，并为高容量富镍正极材料的商业化提供了一种潜在的优化策略。
