Aqueous Zn-ion batteries (ZIBs) have garnered significant interest as an important solution for large-scale energy storage due to their enhanced safety and affordability. Nevertheless, dendrites formation and side reactions faced by Zn anodes have hindered their commercial development. Electrolyte additives, among various methods to stabilize Zn anodes, have emerged as the most commercially viable technique due to their low dosage and potent effects, offering substantial economic benefits. While massive literature reviews have explored strategies for comprehensive Zn anode stabilization, there remains a lack of systematic investigation into electrolyte additives. This review commences by addressing the challenges and root causes faced by Zn anodes, providing essential context for understanding the significance of electrolyte additives. It then proceeds to offer an overview of characterization techniques applied in the analysis of electrolyte additives mechanism. Subsequently, the revie
In aqueous electrolytes, the stability of the zinc anode is threatened by severe dendrite growth and the hydrogen evolution reaction. Herein, diethylene glycol (DEG) is used as an anti-solvent agent to address the abovementioned issues and boost the reversibility of the zinc anode. The DEG has a strong affinity to the Zn anode, thereby steering dominant (002)-textured zinc growth without dendrites. Multiple spectroscopic techniques, theoretical calculations, and molecular dynamics simulation have demonstrated that DEG can reconstruct the solvation sheath of Zn2+ and reduce the amount of active H2O to suppress the hydrogen evolution reaction. This anti-solvent strategy enables the stable cycle life of Zn-Zn cells over 4,200 h, and the Zn-Cu cells deliver a high average coulombic efficiency >99.75% for 1,100 cycles (>2,000 h). Accordingly, zinc-activated carbon full batteries operated steadily for 19,000 cycles (>3 months). This work provides a new anti-solvent strategy for achi
Aqueous zinc-ion batteries (ZIBs) enjoy a good reputation for being safe, affordable to produce, and ecologically friendly due to the use of water-based electrolytes. The main factors restricting the development of ZIBs, however, are the negative effects of dendrite deposition on the zinc anode and the dissolution of common cathodes such as Mn and V-based cathodes. Various techniques have been used to address these issues, including regulating the electrolyte concentration or solvation structure, developing a coating or current collector to lessen anode dendrite growth, and improving the structural stability of the cathode. Recently, functionalized separator strategies have gained popularity as effective ways to improve ZIB performance. The use of a functionalized separator is also a practical technique to save costs and increase the volumetric energy density of the battery by substituting a functionalized separator for the usual thick and expensive glass fiber separator. The developme
Growth of dendrites, the low plating/stripping efficiency of Zn anodes, and the high freezing point of aqueous electrolytes hinder the practical application of aqueous Zn-ion batteries. Here, a zwitterionic osmolyte-based molecular crowding electrolyte is presented, by adding betaine (Bet, a by-product from beet plant) to the aqueous electrolyte, to solve the abovementioned problems. Substantive verification tests, density functional theory calculations, and ab initio molecular dynamics simulations consistently reveal that side reactions and growth of Zn dendrites are restrained because Bet can break Zn2+ solvation and regulate oriented 2D Zn2+ deposition. The Bet/ZnSO4 electrolyte enables superior reversibility in a Zn–Cu half-cell to achieve a high Coulombic efficiency >99.9% for 900 cycles (≈1800 h), and dendrite-free Zn plating/stripping in Zn–Zn cells for 4235 h at 0.5 mA cm−2 and 0.5 mAh cm−2. Furthermore, a high concentration of Bet lowers the freezing point of the
Abstract
Rechargeable aqueous Zn-ion batteries promise high capacity, low cost, high safety, and sustainability for large-scale energy storage. The Zn metal anode, however, suffers from the dendrite growth and side reactions that are mainly due to the absence of an appropriate solid electrolyte interphase (SEI) layer. Herein, the in situ formation of a dense, stable, and highly Zn -conductive SEI layer (hopeite) in aqueous Zn chemistry is demonstrated, by introducing Zn(H PO ) salt into the electrolyte. The hopeite SEI (≈140 nm thickness) enables uniform and rapid Zn-ion transport kinetics for dendrite-free Zn deposition, and restrains the side reactions via isolating active Zn from the bulk electrolyte. Under practical testing conditions with an ultrathin Zn anode (10 µm), a low negative/positive capacity ratio (≈2.3), and a lean electrolyte (9 µL mAh ), the Zn/V O full cell retains 94.4% of its original capacity after 500 cycles. This work provides a simple yet practical s