Redistributing Zn-ion flux by interlayer ion channels in Mg-Al layered double hydroxide-based artificial solid electrolyte interface for ultra-stable and dendrite-free Zn metal anodes

Abstract

The growth of Zn dendrites and self-corrosion reaction during electrochemical cycling is a long-standing issue impeding the practical application of zinc-ion batteries. Although various surface engineering strategies have shown great promise in suppressing zinc dendrites, the protective layers unavoidably hinder Zn2+ diffusion, resulting in increased internal impedance/polarization. Therefore, constructing smart interface protective layers with fast Zn2+ transfer kinetics is highly desirable but remains a key challenge. Here, an Mg-Al layered double hydroxide (LDH)-based artificial solid electrolyte interface (SEI) with Zn-ion diffusion channels is proposed. The well-aligned interlayer channels in the Mg-Al LDH skeleton is proved to efficiently engineer the distribution of Zn2+ ions and facilitate Zn2+ diffusion between the electrode/electrolyte interface, thus giving rise to stable Zn deposition. Moreover, the mechanically robust Mg-Al LDH artificial SEI acts as an interfacial layer to constrain H2O-induced corrosion and hydrogen evolution reaction. Consequently, the Mg-Al LDH artificial SEI improves the Coulombic efficiency to 99.2% for more than 2000 cycles, and an ultralong lifespan of 1400 h has been achieved at 0.5 mA cm−2. Notably, the zinc-ion capacitors by pairing the Zn@LDH anode and high-loading active carbon cathode deliver outstanding cycling stability with a high capacity retention of 93.7% up to 10000 cycles at the high areal current density of 37.5 mA cm−2, portending the feasibility of practical applications.