淡出
氧化还原
空隙(复合材料)
材料科学
阴极
离子
氧气
电压
过渡金属
金属
自行车
容量损失
化学工程
化学物理
电极
纳米技术
复合材料
化学
电气工程
电化学
计算机科学
冶金
物理化学
工程类
操作系统
生物化学
催化作用
有机化学
考古
历史
作者
John‐Joseph Marie,Robert A. House,Gregory J. Rees,Alex W. Robertson,Max Jenkins,Jun Chen,Stefano Agrestini,Mirian García‐Fernández,Ke‐Jin Zhou,Peter G. Bruce
标识
DOI:10.1038/s41563-024-01833-z
摘要
Abstract Oxygen redox cathodes, such as Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 , deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O 2− ions forms O 2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O 2− on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O 2− /O 2 redox process and O 2 loss. The closed voids that trap O 2 grow on cycling, rendering more of the trapped O 2 electrochemically inactive. The size and density of voids leads to cracking of the particles and open voids at the surfaces, releasing O 2 . Our findings implicate the thermodynamic driving force to form O 2 as the root cause of transition metal migration, void formation and consequently voltage fade in Li-rich cathodes.
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