Hyper-Tolerant Chloride/Phosphate-Rich Interphase Embracing Aggressive Zinc Electrochemistry in Hydrated Eutectic Electrolytes

Abstract

The mismatch between solid-electrolyte interphase (SEI) and aggressive Zn electrochemistry greatly impedes the practical development of Zn batteries. Herein, a hyper-tolerant Cl-/PO3--rich SEI in hydrated eutectic electrolyte (HEEs) is initially achieved to embrace aggressive Zn electrochemistry. Resorting to cosolvent-derived phosphates as strong settling agents, Cl- species with ultrahigh Zn2+-conduction is locked to anode interface, configuring the anti-electrolyte erosion and stress-relieved SEI. By simultaneously dredging Zn2+ flux during Zn plating/striping and blocking up electrolyte erosion-induced side reactions, this SEI features a hyper-tolerance to offset synergistic impact from interfacial stress and side reactions, even under harsh conditions. Typically, symmetric Zn cells with the SEI withstand year-level record-long Zn stripping/plating (1.29 years at 1 mA cm-2 with 1 mA h cm-2), ultrahigh accumulative capacity (6.575 A h cm−2 at 5 mA cm-2 with 5 mA h cm-2), and high depth of discharge (DOD, 60%) with a 10-fold longer lifetime (≥ 500 h), far outperforming previous SEIs. Also, the hyper-tolerance of SEI stability is well-kept in full cells coupled with typical intercalation-type cathode materials (e.g., Prussian blue analogue, vanadium oxide). This work unlocks a delicate SEI configuration towards aggressive Zn electrochemistry, which is expected to be extended to other metal batteries.

Keywords: Hyper-tolerant interphase, aggressive Zn electrochemistry, hydrated eutectic electrolytes, endurability, practical Zn batteries