A new spinel high-entropy oxide (Mg_0.2Ti_0.2Zn_0.2Cu_0.2Fe_0.2)₃O₄ with fast reaction kinetics and excellent stability as an anode material for lithium ion batteries

It is well known that transition metal oxides (TMOs) have attracted extensive attention as promising anodes for next-generation lithium ion batteries (LIBs) owing to their low cost and high theoretical capacities. However, the huge volume changes upon lithiation/delithiation cycling gradually cause drastic particle pulverization in the electrodes, thus leading to fast capacity fading and limiting their practical applications. High-entropy oxides with enhanced electronic conductivity and multiple electrochemically active elements display stepwise lithium storage behaviors, thus efficiently alleviating the volume change induced electrode pulverization problem. Herein, we report the synthesis of a new kind of spinel (Mg0.2Ti0.2Zn0.2Cu0.2Fe0.2)3O4 material via a facile one-step solid state reaction method and subsequent high-energy ball-milling. When used as anodes for LIBs, the submicrometer-sized (Mg0.2Ti0.2Zn0.2Cu0.2Fe0.2)3O4 particles exhibit superior lithium storage properties, delivering a large reversible capacity of 504 mA h g-1 at a current density of 100 mA g-1 after 300 cycles, and notably an exceptional rate capacity of 272 mA h g-1 at 2000 mA g-1. Our work highlights that rational design of high-entropy oxides with different electrochemically active elements and novel structures might be a useful strategy for exploring high-performance LIB anode materials in next-generation energy storage devices.