Dual-phase (AlMgCoNiCuZn)O high-entropy oxide embedded in graphite nanosheets with superior lithium storage capability

Abstract

High-entropy oxides (HEOs) are promising anode materials for Li-ion batteries (LIBs) due to their wide component range and tunable Li-storage property. However, low electrical conductivity and sluggish reaction kinetics restrict their practical applications. In this work, a novel (AlMgCoNiCuZn)O HEO-graphite composite (Al-MgTMO/G) was constructed via facile solid-state reaction and scalable ball milling methods. The synthesized composite has an architecture that includes fine Al-MgTMO nanoparticles embedded in ultrathin graphite nanosheets. It is found that Al-MgTMO contains a major rock-salt phase along with a mirror spinel phase, which induces the generation of extra oxygen vacancies. These factors together enhance its Li-ion transport and electrochemical kinetics. Meanwhile, graphite nanosheets can further increase the electrical conductivity and stabilize the structure of Al-MgTMO. As a result, the Al-MgTMO/G composite delivers a high reversible capacity of 949.4 mAh g⁻¹ after 160 cycles at 0.2 A g⁻¹. Additionally, it also exhibits intriguing rate capability of 481.1 mAh g⁻¹ at 2.0 A g⁻¹ and long-term stability of 405.3 mAh g⁻¹ after 400 cycles at 1.0 A g⁻¹. This work presents a simple, efficient and scalable strategy for designing HEO-based anode materials with high lithium storage performance.