Electric Double Layer Oriented Eutectic Additive Design toward Stable Zn Anodes with a High Depth of Discharge

ZnSO₄-based electrolytes for aqueous zinc ion batteries fail to meet practical application metrics due to hydrogen evolution reaction (HER) and dendrite growth. In this work, a highly polarized eutectic additive, glycerophosphorylcholine (GPC) is rationally designed, to regulate the electric double layer (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 Zn_xP_yO_z-rich solid-electrolyte interphase 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 1450 h 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.