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 (Zn0.18Mg0.2Co0.31Ni0.37-Ti-EG (ethylene glycol)) was controllably synthesized through a controllable approach integrating solution self-assembly with hydrothermal techniques. Subsequently, Zn0.18Mg0.2Co0.31Ni0.37-Ti-EG hexagonal prisms were applied as precursors to produce grain--boundary-rich porous hexagonal prism Zn0.18Mg0.2Co0.31Ni0.37TiO3 via sintering under an optimized temperature and air condition. Zn0.18Mg0.2Co0.31Ni0.37TiO3 possesses a high compacted density of 2.234 g cm⁻³. Benefitting from the synergistic effect of high entropy, porous, and grain-boundary-rich structure, the newly developed Zn0.18Mg0.2Co0.31Ni0.37TiO3 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 holds a coulombic efficiency of 99.67% after 800 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.