Cationic synergy and seed-crystal-induced reversible structures unlocking superior lithium storage in high-entropy oxide negative electrode

Abstract

High-entropy oxides (HEOs), offering reversible lithium storage and moderate operating potential, are considered promising negative electrodes. However, the intricate lithium storage mechanism within HE polycationic systems remains challenging. Here, we conduct comprehensive investigations into the electrochemical properties and structural evolution of (CrMnCoNiZn)₃O₄ (HESO) to clarify lithium storage mechanisms. Density functional theory (DFT) calculations reveal that polycationic synergy modulates the electronic structure and d-band centers of HESO, delivering fast electrode kinetics. Exhaustive in- and ex-situ analyses demonstrate that the residual crystalline phases acting as seed crystals maintain the spinel/rock-salt lattice persistence under the entropy stabilization effect, lattice distortion effect, and cation synergy, which guide cation crystallization upon the electric field to drive reversible lithium storage. Such properties underlie the HESO electrode with an exceptional rate and long-term capability. This work clarifies the roles of cationic synergy and seed-crystal-driven structural reversibility, providing a blueprint for designing high-performance HEO negative electrodes for next-generation lithium-ion batteries (LIBs).