Hierarchical Ligand Solvation Directs Organic‐Templated Growth of Ordered ZnF 2 Toward Ultrastable Zn Metal Anode
Yueliang Chen, Qinyang Wang, Zhaoyu Zhang, Guoli Liao, Xiaojia Lan, Yuekai Lin, Wencheng Du, Yufei Zhang, Minghui Ye, Zhipeng Wen, Yongchao Tang, Xiaoqing Liu, Cheng Chao LiABSTRACT
Uncontrolled decomposition of BF 4 − anions in aqueous Zn(BF 4 ) 2 electrolytes tends to generate irregular and loose ZnF 2 precipitates, which aggravate parasitic side reactions and fail to protect the Zn anode. To circumvent this issue, a gradient solvation structure of Zn 2 + , [Zn(H 2 O) 2.5 (NMA) 2.1 (CPL) 0.9 ] 2+ (BF 4 − ) 0.5 , is rationally constructed in a deep eutectic electrolyte by leveraging the hierarchical ligand binding energy sequence H 2 O < N‐methylacetamide (NMA) < ε‐caprolactam (CPL) < BF 4 − . Beyond suppressing water reactivity, the tailored desolvation pathway can direct the stepwise decomposition of BF 4 − and concurrently trigger ring‐opening polymerization of CPL at the interface. The in situ grown poly‐CPL chains serve as a templating matrix that guides the ordered assembly of ZnF 2 nuclei into a compact, uniform organic‐inorganic hybrid solid electrolyte interphase (SEI). Such a distinctive SEI architecture integrates high ionic conductivity from ZnF 2 nanodomains with mechanical flexibility from the polymer network, effectively protects the Zn anode from electrolyte corrosion and dendrite proliferation. Consequently, the symmetric Zn||Zn cell achieves a 100‐fold improvement in cycling lifespan, sustaining stable operation for over 6200 h at 1 mA cm −2 . Meanwhile, the Coulombic efficiency is significantly boosted from 88.5% to 99.4%. This work provides a new paradigm for interface engineering through ligand binding energy regulation.