Anion Capture-Cation Anisotropic Transport Mediator Enables Fast Zinc-Ion Solid Electrolyte Design

Abstract

High tortuosity and low uniformity of the segmental motion, as well as the strong cation-anion interaction would lead to the sluggish transport kinetics and large concentration polarization of solid polymer electrolyte for zinc metal batteries. In this report, an anion capture-cation anisotropic transport model is highlighted to enable fast-charge solid polymer electrolyte design, by using exfoliated zinc phosphate (E-ZPO) nanosheets as functional mediator. As indicated, the Zn²⁺ migration number of polymer electrolyte can be improved from 0.23 to 0.74. Besides, the homogenized ion flux at the Zn-electrolyte interface contributes to the formation of dense organic/inorganic hybrid interphase and Zn(002)-preferential deposition. Thus, the coulombic efficiency and reversibility of Zn plating/stripping can be effectively improved. Unexpectedly, the assembled Zn/V₂O₅ full batteries deliver a high specific capacity of 190 mAh g^-1 even after 5000 cycles at the high current density of 5 A g^-1 and 25°C. Beyond that, a high discharge capacity of 303 mAh g^-1 also can be achieved after 1000 cycles at 5 A g^-1 and 60°C. Such a transport paradigm can be expected to provide a new pathway for constructing high-performance solid-state energy storage devices including but not limited to Zn-ion batteries.