Weakly coordinated TGDE regulating hydrogen bond network and solvated structure for high-rate Zn anodes

With the rapid growth of technologies requiring high-power energy storage, achieving long-term cyclic stability under ultra-high current density is a key challenge. Aqueous zinc-ion batteries (AZIBs) are promising candidates due to their intrinsic safety and low cost, but they suffer from severe interfacial instability at rates exceeding 10 mA cm−2, which drastically shortens their cycle life. Inspired by theoretical calculations, triglyme (TGDE) additive with strong electron-donating groups into Zn(OTf)2 electrolytes effectively disrupts the hydrogen-bond network among free water molecules, while the weak coordination of TGDE with Zn2+ promotes the entry of OTf− into the primary Zn2+ solvated sheath, thus decreasing the coordination number of water with Zn2+. As such, the hydrogen-bond network and the bulk solvated structure are reconstructed with better stability. Moreover, the strong adsorption of TGDE lying on the Zn(002) surface would induce Zn depositions along (002) together with the reduced exposed surface, further effectively inhibiting side reactions. Likewise, TGDE electrolyte induces the formation of such ZnF2-ZnS dual-layer solid electrolyte interface (SEI) with superior chemical stability and ionic conductivity, thereby regulating Zn2+ flux with dendrite-free depositions. Based on this electrolyte, Zn||Zn cells can be stably cycled for 1300 h at a limit of 10 mA cm−2 and 10 mAh cm−2. The assembled Zn||V2O5 full cells still maintain 99.9% capacity retention after 1000 cycles at 10 A g−1. This work provides a feasible approach for designing aqueous electrolytes to reconstruct the hydrogen-bond network and solvated structure, which can be extended to the applications of high-rate and high-temperature scenarios.