Tuning single‐phase medium‐entropy oxides derived from nanoporous NiCuCoMn alloy as a highly stable anode for Li‐ion batteries

Abstract

Abstract Incorporating four cations into a single‐phase oxide is beneficial for maintaining structural stability during Li + insertion/desertion because of the produced entropy‐dominated phase stabilization effects. However, medium‐entropy oxides exhibit inherently poor electron and ion conductivity. As such, in this work, a single ‐ phase medium‐entropy oxide of Ni x Cu y Co z Mn 1– x – y – z O (named as NCCM@oxides(H 2 )) is prepared by modified‐NiCuCoMn alloy through the epitaxial‐growing‐based self‐combustion and hydrogen reduction. During hydrogen reduction, some Cu ions are reduced to elemental Cu (defined as Cu 0 ), which is distributed among the metal oxides, while generating extensive oxygen vacancies around Cu. The synergetic effect between nanoporous metal‐core oxide‐shell structure and enriched oxygen/Cu 0 vacancies greatly enhances the electronic/ionic conductivity. In addition, the lattice of single‐phase quaternary metal oxides has the configuration entropy stability, which enables the rock‐salt structure to remain stable during repeated conversion reactions. Benefiting from the above‐mentioned merits, the anode for Li‐ion batteries with entropy‐stabled NCCM@oxides(H 2 ) composite shows a high specific capacity of 699 mAh·g −1 at 0.1 A·g −1 and ultra‐stable cycling stability, which maintains 618 and 489 mAh·g −1 at 0.1 and 1.0 A·g −1 after 200 cycles, respectively. This is the first use of this novel and simple strategy for modifying medium‐entropy oxides, which paves the way for the development of high‐entropy oxides as high‐performance electrodes.