Electric Double Layer Oriented Eutectic Additive Design towards Stable Zn Anodes with A High Depth of Discharge.

Abstract

ZnSO4-based electrolytes for aqueous zinc ion batteries (AZIBs) fail to meet practical application metrics due to hydrogen evolution reaction (HER) and dendrite growth. In this work, we rationally designed a highly polarized eutectic additive, glycerophosphorylcholine (GPC), to regulate the EDL structure for stable Zn anodes with a high depth of discharge (DOD). On one hand, GPC molecules with abundant hydroxyl groups can precisely regulate the hydrogen bond network in EDL to suppress HER. On the other hand, the enrichment of GPC at the interface is positively responsible for the negative charge density on the Zn surface, which leads to the formation of a robust ZnxPyOz-rich solid-electrolyte interphase (SEI) and terminates dendrite growth in the charge-rich sites. This EDL-oriented eutectic additive engineering enables highly reversible and selectively (002)-textured Zn anodes to operate for over 1450h at a high DOD of 45.3%. Meanwhile, a high-capacity (185.7 mAh g-1) aqueous Zn||VS2 full cell shows remarkable cycling stability over 220 cycles with an excellent capacity retention of 90.4% even at a low current density of 0.1 A g-1 (0.5 C). This work sheds light on electrolyte design and interface engineering for high-performance aqueous batteries. This article is protected by copyright. All rights reserved.