Atomic-Level Regulating Zinc Chemistry by Sn Single-Atom/Carbon-Fibers Armed Gel Electrolyte for Highly Reversible Zinc Anode.

Gel electrolyte has emerged as a desirable candidate for high-safety Zn ion batteries (ZIBs), but it is enormously restricted by the sluggish Zn2+ ion transport and severe electric field distortion at the electrode/electrolyte interface, leading to Zn anode failure. Herein, a unique gel electrolyte with precise atomic-level regulation of Zn2+ migration is developed through incorporating Sn single-atoms (SAs)-loaded carbon fibers (CFs) into the polyacrylamide (PAM) matrix (PAM/CFs@Sn) for building stable Zn anodes. The CFs fillers are introduced into the PAM gel electrolyte, which can promote more uniform Zn2+ flux and charge distribution, thereby alleviating electric-field heterogeneity. Meanwhile, the atomic-level zincophilic Sn SAs sites offer abundant and uniform active centers to lower the Zn2+ migration energy barrier, thereby promoting regular and planar Zn deposition. These combined advantages of the PAM/CFs@Sn gel electrolyte enable Zn anodes to achieve stable cycling up to 3740 h at 0.5 mA cm-2, a high Zn2+ transference number of 0.89 and an average coulombic efficiency of 99.5% over 1480 h, etc. Overall, this work provides a reliable atomic-level zinc chemistry regulating strategy of gel electrolytes toward durable Zn anodes and beyond.