氧化还原
磁滞
过渡金属
锂(药物)
化学物理
阴极
离子
材料科学
金属
氧气
化学
无机化学
凝聚态物理
物理化学
物理
催化作用
医学
内分泌学
生物化学
有机化学
冶金
作者
Kit McColl,Robert A. House,Gregory J. Rees,Alexander G. Squires,Samuel W. Coles,Peter G. Bruce,Benjamin Morgan,M. Saïful Islam
标识
DOI:10.1038/s41467-022-32983-w
摘要
Lithium-rich disordered rocksalt cathodes display high capacities arising from redox chemistry on both transition-metal ions (TM-redox) and oxygen ions (O-redox), making them promising candidates for next-generation lithium-ion batteries. However, the atomic-scale mechanisms governing O-redox behaviour in disordered structures are not fully understood. Here we show that, at high states of charge in the disordered rocksalt Li2MnO2F, transition metal migration is necessary for the formation of molecular O2 trapped in the bulk. Density functional theory calculations reveal that O2 is thermodynamically favoured over other oxidised O species, which is confirmed by resonant inelastic X-ray scattering data showing only O2 forms. When O-redox involves irreversible Mn migration, this mechanism results in a path-dependent voltage hysteresis between charge and discharge, commensurate with the hysteresis observed electrochemically. The implications are that irreversible transition metal migration should be suppressed to reduce the voltage hysteresis that afflicts O-redox disordered rocksalt cathodes.
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