Entropy-induced high-density grain boundaries in Co-free high-entropy spinel oxides for highly reversible lithium storage.

Entropy-induced high-density grain boundaries is favorable for improved capacity and cycling stability. [Display omitted] • Co-free high entropy oxide was synthesized by a simple solution combustion method. • HEO anode exhibits high capacity (1374 mAh g−1) and excellent cycling stability. • High-density grain boundaries contribute to improved capacity and cycling stability. Transition metal oxides (TMOs) with high discharge capacity are considered as one of the most promising anodes for lithium-ion batteries. However, the practical utilization of TMOs is largely limited by cycling stability issues arising from volume expansion, structural collapse. In this study, we synthesized a high-entropy spinel oxide material (FeCrNiMnZn) 3 O 4 using a solution combustion method. With the implementation of five cations through high-entropy engineering, the agglomeration and expansion of the electrode materials during charging and discharging are suppressed, and the cycling stability is enhanced. The results demonstrate that entropy-induced high-density grain boundaries and the reversibility of spinel structure contribute to improved capacity and cycling stability. Herein, (FeCrNiMnZn) 3 O 4 provides a high capacity (1374 mAh g−1) at 0.1 A g−1 and superior cycling stability (almost 100 %) during 200 cycles with a current density of 0.5 A g−1. The study provides valuable understanding for designing the high entropy oxides anode electrodes. [ABSTRACT FROM AUTHOR]