Unlocking Quasi-Solid-State Anode-Free Zinc Metal Batteries Through Robust Bilayer Interphase Engineering

Anode-free aqueous zinc (Zn) metal batteries (AFZMBs) possess an optimal battery architecture configuration because no excess Zn source is involved in the charge/discharge processes, rendering it feasible to enhance the energy density of batteries. However, rapid capacity fading due to the unstable anode-side current collector/electrolyte interfacial chemistry, which results in Zn dendrite growth, impedes their practical application, especially in quasi-solid-state AFZMBs. Herein, a robust bilayer interphase design strategy between a gel electrolyte and a copper current collector is proposed to achieve high-energy and stable quasi-solid-state AFZMBs. Utilizing the upper mass transfer layer to regulate rapid Zn ion transport and the lower zincophilic electron transfer layer to induce initial uniform Zn nucleation and balance the surface electric field, uniform dendrite-free Zn deposition and prominent reversibility are achieved. Therefore, the robust bilayer interphase design strategy significantly improves the cycling stability of quasi-solid-state Zn//I₂ batteries. Additionally, the fabricated quasi-solid-state AFZMBs employing a pre-intercalated VO₂ cathode deliver attractive energy and power densities (186.1 Wh kg⁻¹/470 W kg⁻¹ and 145.3 Wh kg⁻¹/1.74 kW kg⁻¹, based on the active material). Moreover, the successful extension of the bilayer interphase design to flexible AFZMBs offers a promising pathway for the development of wearable electronic devices.