Dragon-Scale-Inspired Phosphate Interface for Enhanced Stability of Zn Powder Anodes

Abstract

The industrialization of aqueous Zn-ion batteries faces critical challenges from Zn powder anodes, particularly dendrite proliferation and parasitic reactions exacerbated by incompatible interfaces in conventional electrolyte systems. While electrolyte engineering can mitigate these issues, fragile inorganic/organic protective layers typically demonstrate poor substrate adhesion and mechanical stability during high-rate cycling. Addressing this fundamental limitation, we propose a biomimetic "dragon-scale-wall" interface through sodium tripolyphosphate (STPP)-mediated electrolyte regulation. Advanced spectroscopic characterization reveals that STPP coordinates Zn2+ to reconstruct the solvation sheath, enabling in situ formation of a chemically-grafted phosphate-rich layer that conformally encapsulates flake Zn powder. This dragon-scale architecture exhibits unprecedented electrode compatibility through optimized charge redistribution and ion-transport channels, achieving remarkable durability with 900 h stable cycling at 8.8 mA cm-2 (0.88 mAh cm-2) in symmetric cells. Additionally, full-battery configurations exhibit a discharge capacity of 60.8 mAh g-1 after 4000 cycles at the current density of 10 A g-1, demonstrating the excellent rate capability among phosphate-modified Zn batteries. The interfacial chemistry paradigm established here provides a scalable pathway toward practical high-power zinc metal batteries through molecular-level compatibility engineering.

Keywords: Zn powder anode, Zn metal battery, Electrolyte, sodium tripolyphosphate additive, interface engineering