Manipulating Electric Double Layer Adsorption for Stable Solid-Electrolyte Interphase in 2.3 Ah Zn-Pouch Cells.

Abstract

Constructing a reliable solid-electrolyte interphase (SEI) is imperative for enabling highly reversible zinc metal (Zn0) electrodes. Contrary to conventional "bulk solvation" mechanism, we found the SEI structure is dominated by electric double layer (EDL) adsorption. We manipulate the EDL adsorption and Zn2+ solvation with ether additives (i.e. 15-crown-5, 12-crown-4, and triglyme). The 12-crown-4 with medium adsorption on EDL leads to a layer-structured SEI with inner inorganic ZnFx/ZnSx and outer organic C-O-C components. This structure endows SEI with high rigidness and strong toughness enabling the 100cm2 Zn||Zn pouch cell to exhibit a cumulative capacity of 4250 mAh cm-2 at areal-capacity of 10mAh cm-2. More importantly, a 2.3 Ah Zn||Zn0.25V2O5•nH2O pouch cell delivers a recorded energy density of 104 Wh Lcell-1 and runs for > 70 days under the harsh conditions of low negative/positive electrode ratio (2.2:1), lean electrolyte (8gAh-1), and high-areal-capacity (~13mAhcm-2).