Reviving Zn Dendrites to Electroactive Zn ²⁺ by Ion Sieve Interface

Abstract

Zn⁰ dendrite formation during repeated plating/stripping processes limits the practical use of Zn-metal anodes in reliable and affordable energy storage. Traditional methods, including dendrite suppression and dendrite regulation, fail under demanding performance conditions due to Zn²⁺ diffusion limitations and concentration gradients. Here, using an in situ pre-zincation approach, a Li₂Zn_xTi_3-xO₈ (LZTO, 0<x<3) layer with uniform ion channels is introduced. This layer acts as an ionic sieve, reviving Zn⁰ dendrite into Zn²⁺ through redox reactions and enhancing Zn²⁺ diffusion kinetics. Experiment and simulation results reveal that Zn²⁺ migrates along the (111) crystal plane of LZTO through the successive replacement of Zn atoms in tetrahedral positions, with a high transference number of 0.796. LZTO@Zn performs better in coin cells at high currents (e.g., 50 mA cm^-2) and operates at higher Zn utilization (300 h at 56.98% Zn utilization), with four times the lifespan at -40 °C and six times longer in alkaline electrolytes compared to bare Zn. Pouch cells with LZTO@Zn anodes operate in a low N/P ratio (6.9) and lean electrolyte (E/C is 20 µL mA h^-1), achieving enhanced cycling stability. The findings indicate the significance of ion sieves with ordered ion channels in mitigating Zn⁰ dendrites and promoting rapid Zn²⁺ transport.