Engineering a zinc anode interphasial chemistry for acidic, alkaline and non-aqueous electrolytes

Abstract

Reversibility and anode utilization remain key barriers to realizing practical, rechargeable Zn metal batteries. Herein, we report a heteroatomic molecule, 3,5-bis(trifluoromethyl)pyrazole (TFMP), capable of promoting a fluorinated and polymeric interphase in every class of zinc electrolyte (acidic, alkaline, non-aqueous). Significant improvements in performance are observed in TFMP-based electrolytes including coulombic efficiencies exceeding 99% and utilizations up to 80%. Notably, dendrite formation is effectively suppressed in all classes of electrolytes with the most impressive performance observed in weakly acidic aqueous media with selective entrainers. In full cells constructed with a thin (10-μm) Zn anode and an organic cathode, excellent performance is demonstrated with an exceptionally low n/p ratio (5.4) and high energy density (270 W h L⁻¹, projected for 18 650 cell) in aqueous media. This work highlights that interphasial chemistries originating from additive-level electrolyte components can manifest major improvements without significantly altering the composition, cost, and key properties of traditional zinc electrolytes that were already optimized.