Controlled synthesis and multi-effect synergistic lithium storage of micron-sized porous hexagonal prismatic titanium-based high-entropy oxide anodes

Abstract

Metal–organic frameworks (MOFs) have emerged as promising precursors or alternative anode materials for lithium-ion batteries (LIBs). In this work, a Ti-based MOF (Zn_0.18Mg_0.2Co_0.31Ni_0.37-Ti-EG (ethylene glycol)) was controllably synthesized through a controllable approach integrating solution self-assembly with hydrothermal techniques. Subsequently, Zn_0.18Mg_0.2Co_0.31Ni_0.37-Ti-EG hexagonal prisms were applied as precursors to produce grain-boundary-rich porous hexagonal prismatic Zn_0.18Mg_0.2Co_0.31Ni_0.37TiO₃via sintering under optimized temperature and air conditions. Zn_0.18Mg_0.2Co_0.31Ni_0.37TiO₃ possesses a high compacted density of 2.234 g cm⁻³. Benefitting from the synergistic effect of a high entropy, porous, and grain-boundary-rich structure, the newly developed Zn_0.18Mg_0.2Co_0.31Ni_0.37TiO₃ exhibits desirable electrochemical performance. It demonstrates impressive cycling stability, maintaining 484.03 mAh g⁻¹ after 100 cycles at 0.2 A g⁻¹. Moreover, it has a coulombic efficiency of 99.83% after 1000 cycles at a high current density of 2 A g⁻¹. This study provides a novel perspective and methodology for developing high-entropy MOF-derived anode materials for energy storage.