Lu Li, Hu Yanjie, Jiang Hao, Zhu Chengxian, Chen Jinyu, Li Chunzhong
Key Laboratory for Ultrafine Materials of Ministry of Education, Shanghai Engineering Research Center of Hierarchical Nanomaterials, School of Materials Science and Engineering , East China University of Science & Technology , Shanghai 200237 , China.
ACS Appl Mater Interfaces. 2019 Jul 24;11(29):25796-25803. doi: 10.1021/acsami.9b03905. Epub 2019 Jun 5.
Lithium-manganese-rich layered oxides have sparked intense interest on high-energy-density lithium-ion batteries because of their unique anionic redox. While making efforts to adjust the primary particle size for the improved electrochemical kinetics, current research is insufficient to explain how the anionic/cationic interplay governs the electrochemical behavior except for ion diffusion. Here, fully ordered LiMnNiCoO spheres of shortened primary particle size were synthesized via the coprecipitation method for use as cathodes. A high discharge capacity of 303.2 mA h g was achieved for the first cycle. Optimized nanostructures reduce the lithium ion diffusion length and increase electronic conductivity unsurprisingly, contributing to excellent electrochemical activity and rate capability. Furthermore, the decreased primary particle size accelerated the redox reactivity of cations and the reversibility of anionic redox on path dependence. This work clarifies the electrochemical mechanism of cationic/anionic redox of these Li-rich layered oxides and provides a new vision for a unique design of high-energy cathode materials with better application.
富锂锰基层状氧化物因其独特的阴离子氧化还原特性，在高能量密度锂离子电池领域引发了广泛关注。尽管人们致力于调整一次粒径以改善电化学动力学，但目前的研究仍不足以解释除离子扩散外，阴离子/阳离子相互作用是如何控制电化学行为的。在此，通过共沉淀法合成了具有缩短一次粒径的完全有序LiMnNiCoO球状物用作阴极。首次循环实现了303.2 mA h g的高放电容量。不出所料，优化的纳米结构缩短了锂离子扩散长度并提高了电子导电性，有助于实现优异的电化学活性和倍率性能。此外，减小的一次粒径加速了阳离子的氧化还原反应活性以及阴离子氧化还原在路径依赖性上的可逆性。这项工作阐明了这些富锂层状氧化物阳离子/阴离子氧化还原的电化学机制，并为具有更好应用前景的高能阴极材料的独特设计提供了新视角。
