Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

Abstract

Aqueous Zn-ion batteries (AZIBs) have received considerable attention owing to their various advantages such as safety, low cost, simple battery assembly conditions, and high ionic conductivity. However, they still suffer from serious problems, including uncontrollable dendrite growth, corrosion, hydrogen evolution reaction (HER) from water decomposition, electrode passivation, and unexpected by-products. The creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these issues. Herein, we propose the use of a perovskite CaTiO₃ (CTO) protective layer on Zn (CTO@Zn) as a promising approach for improving the performance of AZIBs. The CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant (ε_r = 180) and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn²⁺ ions in the CTO layer. By avoiding the direct contact of the Zn anode with the electrolyte solution, the uneven dendrite growth, corrosion, parasitic side reactions, and HER are mitigated, while CTO retains its mechanical and chemical robustness during cycling. Consequently, CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare Zn. CTO@Zn shows steady overpotential (∼68 mV) for 1500 h at 1 mA cm⁻²/0.5 mA h cm⁻², excelling bare Zn. Moreover, when paired with the V₂O₅-C cathode, the CTO@Zn//V₂O₅-C full battery delivers 148.4 mA h g⁻¹ (based on the mass of the cathode) after 300 cycles. This study provides new insights into Zn metal anodes and the development of high-performance AZIBs.