Enhanced Kinetics and Stability of Zn-MnO₂ Batteries with a Multifunctional TiO₂ Coating.

Abstract

Zinc-ion batteries are a promising energy storage alternative, offering safety, cost-effectiveness, and environment-friendliness. MnO₂ is appealing for its high capacity and output voltage, but it suffers from slow kinetics and poor stability due to severe Mn dissolution during cycling. Here, the performance of MnO₂ is enhanced by coating it with a uniform TiO₂ nanolayer that incorporates oxygen vacancies. The TiO₂-MnO₂ heterogeneous interface results in the formation of Ti─O─Mn bonds and a reduction in the interfacial valence state, thereby leading to the creation of an interface electron-enriched region that facilitates faster electron and ion transport. This multifunctional TiO₂ coating not only promotes proton-dominated electrochemical reactions and ion diffusion but also acts as a protective barrier, preventing Mn dissolution and buffering volume changes during cycling. Consequently, the MnO₂@TiO₂ cathode demonstrates excellent specific capacity (299 mAh g^-1 at 0.1 A g^-1) and cycling stability, achieving 91.4% capacity retention after 2500 cycles at 1 A g^-1 and 92.7% capacity retention after 600 cycles at a low current density of 0.2 A g^-1. These results outperform many previously reported manganese-based cathodes, demonstrating MnO₂@TiO₂'s potential as a high-performance and durable cathode material for zinc-ion batteries and advancing the development of efficient energy storage solutions.