High-Entropy Metal Oxide (NiMnCrCoFe)3O4 Anode Materials with Controlled Morphology for High-Performance Lithium-Ion Batteries

Abstract

High-entropy metal oxides (HEMOs) with several functional properties, including high structural stability and superior conductivity, have been recently utilized in energy-storage devices. Morphology control is the key factor to optimizing HEMO performance for successful use in lithium-ion anode materials. Hence, in this study, HEMO ((NiMnCrCoFe)3O4) was synthesized via a hydrothermal reaction and subsequent post-annealing process, where cetyltrimethylammonium bromide (CTAB) and urea were used to optimize the morphological structure of HEMO particles to ensure a bimodal distribution. A bimodal particle distribution of HEMO was observed and the electrochemical performance was also investigated for an anode in lithium-ion batteries (LIBs). The proposed bimodal HEMO manifests a superior electrochemical performance compared to existing HEMO, which is controlled by uniform nanoscale or micro-sized secondary particles. The present study shows that collective metal cations with different ionic radii, valence states, and reaction potentials, and a diversification of structures, enable a synergistic effect for the excellent performance of HEMOs in LIBs. The proposed HEMO shows an improved initial discharge capacity of 527 mAh g−1 at a high current density of 5 A g−1 compared to the other referred HEMO systems, and 99.8% cycle retention after 300 cycles. Further, this work allows a new approach for designing multi-element transition metal oxide anode materials using a high-entropy strategy, which can be employed in the development of advanced LIBs.