Kinetics-Mediating Artificial Interphase for Ultrafast Zn Metal Anodes

Abstract

Achieving long-term cycling stability of Zn metal anodes at high rates is crucial for the practical applications of aqueous Zn ion batteries. However, the sluggish kinetics of Zn deposition and uncontrollable dendrite growth at the electrolyte/electrode interface will inevitably lead to inferior energy efficiency and limited cycling lifespan. To address these challenges, a consecutive kinetics-mediating mechanism is proposed through the development of an in situ crafted amorphous zinc pyrophosphate (ZPPO) artificial interphase on the Zn anode (ZPPO@Zn). Experimental and theoretical analyses indicate that the designed interphase can not only drive homogeneous ion diffusion and high Zn²⁺ enrichment at the reaction interface, but also simultaneously lower the Gibbs free energy of Zn²⁺ deposition, thus enabling dendrites-free and kinetics-boosted Zn electrodeposition under high current densities. Notably, the ZPPO@Zn electrode demonstrates exceptional long-term lifespans, e.g., over 2800 and 750 h of stable cycling in symmetrical cells at high current densities of 20 and 40 mA cm⁻², respectively, with low overpotential. Even under the challenging cycling condition of ultra-high depth of discharge (DOD) of 80%, a steady cycling over 130 h is maintained. This study provides new insights into the design and optimization of interfacial engineering for fabricating high-performance Zn metal anodes.