A Bilayer Electrode Architecture Enabling SnO<sub>2</sub>-Induced Spatial-Controllable Zinc Deposition for Ultra-High-Areal-Capacity Zinc-Based Flow Batteries.

Li, Yunxuan; Zhou, Mingyue; Shu, Xueqian; Guan, Zijian; Chen, Xi; Wu, Weicheng; Zhang, Tianchen; Liu, Xinyue et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

Aqueous zinc-based flow batteries (ZFBs) show great promise for large-scale energy storage. However, the practical deployment of ZFBs is hindered by a limited areal capacity, due to uncontrolled zinc deposition and low utilization of electrode volume. Herein, we propose a spatially controllable deposition strategy enabled by a bilayer electrode architecture, featuring a SnO<sub>2</sub>-functionalized carbon felt (CF) as the bottom layer and a pristine CF as the top layer. This architecture introduces a steep gradient in nucleation overpotential and zincate affinity that counteracts the ionic migration trend, reversing the deposition behavior from surface-clogging mode to internal-to-external filling. This unique mechanism enables an ultrahigh areal capacity of 330 mAh cm<sup>-2</sup> and an ultrahigh volumetric capacity of 1100 mAh cm<sup>-3</sup>, representing a 65% improvement over conventional electrodes. Even under a harsh condition of 100% state of charge and 100% depth of discharge at 240 mAh cm<sup>-2</sup>, the battery demonstrates exceptional durability over 175 cycles. This work significantly expands volume utilization for zinc deposition via a bilayer electrode design, providing a robust strategy for regulating spatial deposition behavior and paving the way for practical high-areal-capacity ZFBs.