Grain-Oriented Dissolution Enabled by Hydrogel for Highly Reversible Zn Anodes

The reversibility of Zn anodes is severely compromised by dendritic growth and parasitic hydrogen evolution reactions. Directing Zn to undergo grain-oriented stripping offers an effective approach to mitigating these issues. However, this strategy has rarely been explored, and the underlying mechanism remains unclear. Herein, we design a multifunctional hydrogel composed of aramid nanofiber-polyvinyl alcohol (ANF-PVA) and calcium lignosulfonate (LS) to dynamically regulate the anode interface. The ANF-PVA hydrogel framework possesses excellent mechanical stability and a uniform porous structure that promotes a homogeneous electric field distribution. Concurrently, the incorporated LS preferentially adsorbs onto specific Zn crystal planes, which equilibrates the stripping energy barrier. Through the synergistic regulation between ANF-PVA and LS, grain-oriented dissolution is achieved. The in situ formed solid electrolyte interphase (SEI) can further guide uniform Zn deposition and effectively suppress side reactions. Consequently, Zn||Zn symmetric cells exhibit exceptional cycling stability under both ambient (5000 h at 2 mA cm^-2/1 mAh cm^-2) and low-temperature conditions (10 900 h at -40 °C). The Zn||I₂ full cell achieves 78.2% capacity retention after 20 000 cycles at 5 A g^-1. Remarkably, pouch-type cells also sustain 700 cycles. This work opens a new avenue for achieving highly reversible Zn anodes through grain-oriented dissolution.