Abstract High entropy oxide (HEO) is a new-type inorganic material composed of multiple principle metal elements with a single-phase structure and is proved to display many potential unexpected properties such as high structural stability and superionic conductivity. Herein, a novel spinel-structured high entropy oxide (FeCoNiCrMn)3O4 is prepared by high-temperature solid state reaction and evaluated as anode for lithium-ion batteries (LIBs). In-situ high-temperature X-ray diffraction (HT-XRD) is used to reveal structure evolution of mixed oxides with the calcination temperature increase and a single-phase spinel-structured (FeCoNiCrMn)3O4 is obtained at 900 °C. The effect of temperature on structure and electrochemical performance of HEO were investigated, and the HEO-900 anode with commercial mass loading exerts higher capacity (discharge/charge, 1034/680 mAh g−1) and better rate capability (182 mAh g−1 at 2 Ag-1) than HEO-950 and HEO-1000 for its moderate particle size, and all the three samples show excellent cycling stability. Ex-situ XRD and transmission electron microscope are applied to unravel the lithium-storage mechanism of (FeCoNiCrMn)3O4, an amorphization reaction process occurs during the initial discharging and the amorphous structure is maintained in subsequent cycles. The synergetic effect of multiple metal cations with different radius, valence states and reaction potentials and entropy stabilization effect make the HEO display a superior electrochemical performance in LIBs. This work provides a new concept to design multi-element transition metal oxide anode materials by high entropy strategy.

中文翻译：

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尖晶石结构的高熵氧化物 (FeCoNiCrMn)3O4 作为负极以实现优异的锂存储性能

摘要 高熵氧化物（HEO）是一种由多种主要金属元素组成的单相结构的新型无机材料，被证明具有许多潜在的意想不到的特性，如高结构稳定性和超离子导电性。在此，通过高温固相反应制备了一种新型尖晶石结构的高熵氧化物 (FeCoNiCrMn)3O4，并将其用作锂离子电池 (LIBs) 的负极。原位高温 X 射线衍射 (HT-XRD) 用于揭示混合氧化物随煅烧温度升高的结构演变，并在 900 °C 下获得单相尖晶石结构 (FeCoNiCrMn)3O4。研究了温度对 HEO 结构和电化学性能的影响，商业质量负载的 HEO-900 负极发挥了更高的容量（放电/充电，1034/680 mAh g-1) 和比 HEO-950 和 HEO-10​​00 更好的倍率性能（2 Ag-1 时为 182 mAh g-1），因为其中等粒径，并且所有三个样品都显示出优异的循环稳定性。应用非原位XRD和透射电子显微镜揭示了(FeCoNiCrMn)3O4的储锂机制，在初始放电过程中发生非晶化反应过程，在随后的循环中保持非晶结构。具有不同半径、价态和反应电位的多种金属阳离子的协同效应和熵稳定效应使 HEO 在 LIBs 中显示出优异的电化学性能。这项工作为通过高熵策略设计多元素过渡金属氧化物负极材料提供了新的概念。