Construction of hollow mesoporous ZnMn₂O₄/C microspheres with carbon nanotubes embedded in shells for high-performance aqueous zinc ions batteries

Recently, rechargeable zinc-ion batteries have been considered as the future development direction of large-scale energy storage due to their low price, safety, environmental friendliness, and excellent electrochemical performance. However, high-capacity, long-cycle stable cathode materials that can meet the demand are still to be developed. Herein, the hollow mesoporous ZnMn₂O₄/C microsphere cathode material with carbon nanotubes embedded in the shell was prepared by spray pyrolysis for the first time. Its capacity remained at 209.71 mAh·g⁻¹ after 150 cycles at a rate of 0.5 A·g⁻¹, and still maintained a specific capacity of 100.06 mAh·g⁻¹ at a rate of 1 A·g⁻¹ after 1,000 cycles. The outstanding performance is attributed to the hollow structure that can effectively buffer large volume changes caused by ion intercalation and deintercalation, excellent porosity, cationic defects, and high electrical conductivity of carbon nanotubes and its strong adsorption to ZnMn₂O₄ nanoparticles.