Designing interphases for highly reversible aqueous zinc batteries
Glenn Pastel, Travis P. Pollard, Qian Liu, Sydney N. Lavan, Qijia Zhu, Rongzhong Jiang, Lin Ma, Justin G. Connell, Oleg Borodin, Marshall A. Schroeder, Zhengcheng Zhang, Kang Xu
Abstract
Recent efforts to improve zinc metal anode reversibility in aqueous electrolytes have primarily focused on tailoring Zn 2+ solvation. We propose a complementary approach to directly engineer the anode interphase with the help of two co-cations. The designed organic co-cations offer distinct improvements: a partially fluorinated pyrrolidinium cation effectively suppresses parasitic reactions such as hydrogen evolution (<6 μA cm −2 ), while an ether-functionalized ammonium cation inhibits dendrite formation (almost 10 Ah cm −2 cumulative capacity, >1 year, Zn||Zn). Only 3 wt % of the co-cation combination enables full utilization of a 5-mAh cm −2 reservoir with over 99% Coulombic efficiency and 1,000 cycles with 20% reservoir utilization. We further validate this concept in Zn metal batteries with various cathode chemistries (O 2 , polyaniline, and HNaV 6 O 16 ), and we have achieved significant enhancements in performance. This suggests co-cations are a promising and universal approach to improve metal anode reversibility across emerging battery chemistries.