Dong Shengde, Zhou Yuan, Hai Chunxi, Zeng Jinbo, Sun Yanxia, Ma Yanfang, Shen Yue, Li Xiang, Ren Xiufeng, Sun Chao, Zhang Guotai, Wu Zhaowei
Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, 18th Xinning Road, Xining 810008, China.
Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Xining 810008, China.
ACS Appl Mater Interfaces. 2020 Aug 26;12(34):38153-38162. doi: 10.1021/acsami.0c10459. Epub 2020 Aug 14.
Li-rich, manganese-based cathode materials are attractive candidates for Li-ion batteries because of their excellent capacity, but poor rate and cycle performance have limited their commercial applications. Herein, Li-rich, manganese-based cathode materials were modified with aluminum isopropoxide as an aluminum source modifier using a sol-gel technique followed by a wet chemical method. To investigate the structure, morphology, electronic state, and elemental composition of both pristine- and surface-modified LiNiCoMnO, various characterizations were performed. Based on density functional theory simulations and the results of electrochemical tests, the surface of the modified cathode material was found to contain at least part of the LiAlO phase. This was attributed to the aluminum isopropoxide reacting with a LiCO/LiOH byproduct on the material surface to form LiAlO with a three-dimensional Li-ion channel structure. Electrochemical testing revealed that a 3 wt % aluminum isopropoxide coating of cathode materials exhibited excellent electrochemical performance. Furthermore, the initial Coulombic efficiency and discharge capacity at 0.1 C were up to 88.55% and 272.7 mAh g, respectively. A final discharge capacity of 186.4 mAh g was achieved, corresponding to a capacity retention of 83.55% after 300 cycles at 0.5 C. This was attributed to LiAlO partially accelerating the diffusion of Li ions and AlO aiding the avoidance of side reactions in the mixed coating layer by partially protecting the structure.
富锂锰基正极材料因其优异的容量而成为锂离子电池极具吸引力的候选材料，但较差的倍率性能和循环性能限制了它们的商业应用。在此，以异丙醇铝作为铝源改性剂，采用溶胶-凝胶技术并结合湿化学方法对富锂锰基正极材料进行改性。为了研究原始的和表面改性的LiNiCoMnO的结构、形态、电子态和元素组成，进行了各种表征。基于密度泛函理论模拟和电化学测试结果，发现改性正极材料的表面至少含有部分LiAlO相。这归因于异丙醇铝与材料表面的LiCO/LiOH副产物反应形成具有三维锂离子通道结构的LiAlO。电化学测试表明，正极材料3 wt%的异丙醇铝涂层表现出优异的电化学性能。此外，在0.1 C下的初始库仑效率和放电容量分别高达88.55%和272.7 mAh g。最终实现了186.4 mAh g的放电容量，对应于在0.5 C下300次循环后的容量保持率为83.55%。这归因于LiAlO部分加速了锂离子的扩散，并且AlO通过部分保护结构有助于避免混合涂层中的副反应。
