With the rapid development of renewable energy, the demand for large-scale energy storage systems has grown significantly. While lithium-ion batteries have been successfully deployed in portable devices such as electric vehicles and smartphones, their inherent limitations—including high cost, safety concerns, and environmental toxicity—restrict their scalability for large-scale energy storage applications. Recently, aqueous electrolyte-based energy storage devices have garnered increasing attention, with aqueous zinc metal batteries (AZMBs) emerging as a particularly promising candidate. This is attributed to the natural abundance of zinc in the crust and the high theoretical capacity of the zinc anode (820 mAh g⁻¹ and 5855 mAh cm⁻³). Despite these advantages, the chemical properties of zinc metal and aqueous electrolytes pose significant challenges to AZMB commercialization. Notably, the working potential of zinc metal (-0.76 V vs. standard hydrogen electrode) is close to that of the hydrogen evolution reaction (HER), leading to side reactions and corrosion that severely hinder the long-term reversibility of the anode. To address these challenges, this thesis explores electrolyte engineering as a strategy to enhance AZMB performance by optimizing three key electrolyte components—additives, co-solvents, and salts—through the lens of solvation structure and solid electrolyte interphase (SEI) theory. Specifically, it focuses on: i) designing buffer-like additives for AZMBs, ii) mastering cathode and anode electrolyte interphases in vanadium-based zinc batteries via solvation structure control, and iii) electrical double-layer and solvation structure control through a high-concentration dual-salt system. In the first study, the novel electrolyte additive (histidine) was introduced into the conventional ZnSO4 electrolyte. The strong cationic specific absorption between the additive molecule and zinc anode regulated the behavior of Zn2+ deposition and inhibited HER. Significantly, histidine's unique buffer-like functional groups can further alleviate by-product generation by stabilizing electrolyte interphase pH value. With such an electrolyte additive, Zn

Zn symmetric cell can run for more than 3000 h under the current density of 2 mA cm-2. When zinc anodes were coupled with an activated carbon cathode with a mass loading of 8 mg cm-2, the powering device showed high reversibility. Although additives can enhance the performance of zinc metal anodes, their low concentration limits their ability to significantly alter the solvation sheath structure. So, in the second project, methyl acetate (MA) as a cosolvent were introduced into an aqueous electrolyte based on Znic triflate (Zn(OTf)2) through a salting-in effect. Regulating the solvation sheath structure of Zn2+ enables the formation of cathode electrolyte interphase and anode electrolyte interphase, enhancing the stability of the vanadium-base cathode and zinc metal anode, respectively. The incorporation of this cosolvent allows for prolonged operation of Zn//Cu half-cells for over 1500 cycles with the average columbic efficiency of 99.82% under a current density of 1 mA cm-2. While the introduction of organic solvents into electrolytes can compromise the advantages of aqueous systems, we designed a high-concentration dual-salt aqueous electrolyte to address the limitation associated with organic cosolvent. In our third study, a highly soluble and reduction-active lithium salt was introduced into conventional electrolytes, enabling significant enhancements in the zinc anode's reversibility by modifying the solvation structure and electric double layer. At the cathode, ion adsorption on the surface restructured the electric double layer, effectively reducing the dissolution of active materials. Using this electrolyte, full cells with high-mass-loading NaV3O8·1.5H2O (NVO) cathodes (5 mg cm⁻²) and a low negative-to-positive (N/P) ratio of 3 retained 95% of their capacity after 250 cycles. Remarkably, even at -45 °C, the batteries exhibited nearly 100% capacity retention after 500 cycles. This work underscores the potential of high-concentration lithium salts to enhance the stability of aqueous zinc batteries by modulating solvation structures and interfacial chemistry.