Dendrite-free Zn anode enabled by anionic surfactant-induced horizontal growth for highly-stable aqueous Zn-ion pouch cells

Abstract

Aqueous zinc-ion batteries are receiving considerable attention, owing to their intrinsic safety and high theoretical capacity; however, they still suffer from a limited lifespan, caused by severe side reactions and Zn dendrite growth. A common strategy to address these issues involves regulating the solvation structure using specific electrolyte additives to realize the preferred Zn (002) orientation. Herein, we introduce an anionic sodium 3,3′-dithiodipropane sulfonate (SPS) surfactant as a novel electrolyte additive, which differs from traditional surfactants in its negligible impact on the solvation structure. First-principles calculations revealed that the SPS anions tend to adsorb on other facets rather than (002), effectively constraining the electrodeposition of Zn in the (002) orientation. Real-time in situ electrochemical atomic force microscopy was employed to characterize the Zn electrodeposition behavior. With the aid of the SPS additive, the surface corrosion, hydrogen evolution, and dendrite growth were significantly inhibited. As a result, an impressively high accumulated capacity of more than 12 000 mA h was successfully achieved using a Zn‖Zn symmetric pouch cell with an area of 3 × 5 cm², rather than the commonly used coin cells; this shows the great potential of the present system for practical applications. We further assembled a zinc-ion pouch cell consisting of a V₂O₅·H₂O cathode and a zinc anode, which delivered a remarkably high areal capacity of ca. 2 mA h cm⁻² and a good capacity retention of 82.8% after 200 cycles; these performances are superior to those of most aqueous zinc-ion batteries reported previously.