Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences, Zhejiang 315201, China.
Department of Nano Engineering, University of California San Diego (UCSD), La Jolla, California 92093, USA.
Nat Commun. 2016 Jul 1;7:12108. doi: 10.1038/ncomms12108.
Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas-solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g(-1) with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g(-1) still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.
晶格氧在电化学过程中可以发挥有趣的作用，不仅可以维持结构稳定性，还可以影响锂离子电池中高容量氧化物阴极材料中的电子和离子传输性能。在这里，我们报告了一种气固界面反应的设计，通过均匀地产生氧空位来实现氧活性的精细控制，而不会影响富锂层状氧化物的结构完整性。理论计算和实验表征表明，氧空位在体相内提供了有利的离子扩散环境，并显著抑制了表面的气体释放。目标材料可实现高达 301 mAh g-1 的放电容量，初始库仑效率为 93.2%。经过 100 次循环后，在没有明显电压衰减的情况下，可逆容量仍保持在 300 mAh g-1 左右。这项研究为下一代锂离子电池中过渡金属氧化物系统的氧活性的综合设计和控制提供了思路。
