Organic Small Molecules of Hydroxy-Rich Vitamins as Electrolyte Additives for Inducing Dendrite-Free and High-Performance Aqueous Zn-Ion Batteries

Aqueous Zn-ion batteries (AZIBs) have the potential to become next-generation energy storage due to their high safety, excellent economy, and environmental-friendly properties. However, their promising applications are severely hindered by uncontrolled dendrite formation, interfacial corrosion, and low Coulombic efficiency (CE) on Zn metal anodes. Herein, as a type of organic small molecule, hydroxy-rich B-group vitamin (HRV), has been proposed as functional electrolyte additive to increase electrolyte wettability, disperse Zn deposition, improve electrode stability, and prolong the working lifespan of Zn metal anodes. Numerous hydroxyl groups in HRV additives can achieve adsorption onto the electrode surface, which can relieve the attack of free water, attract migrated Zn ions, and promote homogeneous distribution. Specifically, as investigated by DFT calculations, stronger adsorption effects between HRV and the Zn (100) and (101) planes are determined, causing selective exposure of the (002) plane and subsequent planar and dendrite-free Zn plating. Benefiting from these positive effects, an ultralong cycling performance of 2500 h at 1 mA cm–2, excellent rate capability of 1600 h under 10 mA cm–2 (symmetric cell), and superior CE of 99.89% at 5 mA cm–2 (asymmetric cell) are delivered by AZIBs utilizing the electrolyte modified with HRV.