Recent advances in stabilization strategies for zinc anodes in aqueous zinc-ion batteries

Research Background

With the global economy growing rapidly, energy demand keeps rising, and massive fossil fuel combustion causes severe environmental issues like the greenhouse effect. This has pushed countries such as China to take "carbon peaking" and "carbon neutrality" as national policies, accelerating the development of clean energy like solar and wind power—all of which require low-cost, high-efficiency energy storage systems (ESSs). Lithium-ion batteries (LIBs), the current mainstream secondary batteries, use flammable and toxic organic electrolytes due to their operating voltage exceeding water’s thermodynamic stability window (1.23 V), leading to inherent safety risks . Aqueous zinc-ion batteries (AZIBs) stand out as a promising alternative, thanks to low cost, high safety, eco-friendliness, Zn’s high theoretical capacity (820 mAh/g), low redox potential (-0.76 V vs. standard hydrogen electrode), and abundant resources (about 200 times that of lithium). However, Zn anode instability—including dendrite growth, interfacial side reactions, and hydrogen (H₂) evolution—has become a major barrier to AZIB commercialization.

Research Content

The study comprehensively summarizes four core strategies to stabilize Zn anodes in AZIBs. First, artificial solid electrolyte interphase (SEI) layers: unlike LIBs that form self-passivating SEI layers, AZIBs need artificial ones (inorganic, organic, composite types) to isolate Zn anodes from electrolytes, regulate uniform Zn²⁺ deposition, and suppress side reactions. Second, electrolyte modification: this optimizes interfacial behavior via additives (hydrogen bonding, electrostatic, reactive types) and tailored systems (hydrogel-based, high-concentration "water-in-salt", pH-buffered), reducing active water content and inhibiting H₂ evolution. Third, bioinspired strategies: mimicking natural mechanisms—such as frost-resistant plants (hydroxyl-rich additives), macroalgae (sodium alginate chelating Zn²⁺), and mussel adhesion proteins (polydopamine networks)—to enhance anode stability. Fourth, structural optimization: using 3D porous frameworks, pore engineering, and composite anodes to reduce local current density, uniform electric field distribution, and promote homogeneous Zn deposition

Research Results

The four strategies show remarkable effectiveness. Artificial SEI layers (e.g., C₈TAB-modified) enable symmetric cells to cycle stably over 2500 h with 99.8% Coulombic efficiency (CE), while full cells retain 85% capacity over 1000 cycles; a machine-learned Ce-Fe MOF SEI layer extends symmetric cell cycle life to over 4300 h. Electrolyte modification: hydrogel electrolytes allow VO₂ full cells to work at -10–40°C, and high-concentration electrolytes with silk peptides cut Zn deposition overpotential from 200 to 80 mV and triple cycle life. Bioinspired strategies: sodium alginate-modified anodes maintain stable stripping/deposition with 0.114 V overpotential even at high discharge depth. Structural optimization: 3D-RFGC@Zn cycles 3000 times at 120 mA/cm² with 99.67% CE; composite anodes reduce deposition overpotential from 120 to 50 mV. Among the strategies, electrolyte modification is most industrially feasible for its scalability and cost-effectiveness.

Research Significance

Academically, the review clarifies the mechanisms of Zn anode failure (dendrite growth, side reactions) and provides a systematic theoretical framework for future research, while integrating machine learning and bioinspired design opens new paths for energy storage materials. Industrially, it guides AZIB industrialization: electrolyte modification can be rapidly applied to large-scale energy storage, and the "structure-electrolyte-SEI" synergistic strategy overcomes high-discharge-depth interfacial failure, promoting long-life, high-energy-density AZIBs. Environmentally, it advances eco-friendly AZIBs (non-flammable electrolytes, abundant Zn), aligning with global "carbon neutrality" goals and supporting the clean energy transition.