Dongdong Wang

S: Aqueous four-electron zinc-iodine (Zn-I2) batteries offer a route to energy-density storage, yet they are severely hampered by sluggish I−/I0/I+ conversion kinetics and electrolyte freezing at subzero temperatures. Here, we report a frost-resistant electrolyte engineering strategy utilizing guanidinium chloride (GuHCl) as an additive, selected based on its unique ion−dipole interactions and coordination capabilities. The GuH+ exerts electrostatic effects, disrupting the tetrahedral hydrogen-bond network of free water. This structural reconfiguration suppresses electrolyte solidification and accelerates Zn2+ transport kinetics at low temperature. Simultaneously, GuH+ exhibits coordination affinity toward both polyiodide intermediates and ICl2− species. This interaction mitigates the polyiodide shuttle effect and inhibits I+ hydrolysis, thereby enhancing the I−/I0/I+ conversion kinetics in the cold. As a result, the formulated electrolyte enables Zn-I2 pouch cells to achieve reversibility, long cycling stability of 1100 cycles, and low operating temperature at –60 °C, achieving a capacity–temperature−lifespan balance that surpasses most reported low-temperature Zn-metal pouch cells.

Electrolyte additive engineering is regarded as an effective strategy for dual-interface optimization in four-electron aqueous zinc–iodine batteries (AZIBs). However, realizing durable Ah-level AZIBs with industrial-grade parameters (≥10 mg cm–2 I2 cathode mass loading, ≥5 mAh cm–2 Zn anode areal capacity) remains a significant hurdle. Here, we compare various nitrogen-containing cationic ligands to evaluate their synergistic regulation on iodine immobilization and Zn nucleation. This screening successfully establishes N-methylimidazolium chloride (MImCl) as a premier electrolyte additive for stabilizing dual-interface coordination. Upon discharging, the adsorption of MIm+ on the I2 cathode enables electrostatic binding with polyiodides and ICl2–. This interaction not only suppresses the polyiodide shuttle but also shields the I+ species from hydrolysis, promoting a robust and reversible four-electron I–/I0/I+ redox chemistry at elevated I2 mass loading. On the Zn anode, MIm+ preferentially adsorbs onto its surface during charging, accelerating Zn2+ deposition kinetics for dendrite suppression while passivating parasitic reactions, realizing uniform large-capacity Zn plating/stripping. As a result, the engineered 1.4 Ah four-electron Zn||I2 pouch cells achieve an excellent cyclability of 800 cycles and an ultrahigh cathode-mass-specific energy density of 455 Wh kg–1, surpassing most aqueous Zn-based systems in the Ah-class regime.

While constructing anion-involved solvation structures is key to improving electrolyte performance at low temperatures (LTs), conventional strategies that primarily manipulate Li⁺–solvent interactions present significant challenges. These include weakened anion coordination, impeded ion transport, and aggravated interfacial side reactions, making the realization of effective LT operation elusive. Here, we propose a "polarity-contrast" electrolyte design strategy, which enables the construction of a LT-stable, anion-rich solvation structure through deliberate regulation of anion–solvent interactions. The solvent pairs, dimethoxymethane (DMM) and fluoroethylene carbonate (FEC), which exhibits the lowest and highest maximum electrostatic potential, respectively, were selected for electrolyte engineering. At LTs, the weakened interactions between primary solvent DMM and FSI^– promote the coordination of solvation of anions. Meanwhile, the coordinated FEC cosolvent enhances ion–dipole interactions with FSI^–, further anchoring these anions within the solvation sheath. This FSI^–-dominated solvation environment facilitates the formation of a fluorine-rich solid electrolyte interphase, which in turn enables uniform Li deposition under LT conditions. Therefore, Li||SPAN full cells demonstrate excellent LT performance, including a high areal capacity of 4.5 mAh cm^–2 and 150 cycles with 80% retention at −40 °C. Notably, Ah-level Li||SPAN pouch cells demonstrate 50 cycles at −20 °C with exceptional capacity–temperature–lifespan balance, surpassing the most reported LT LMBs.

Aqueous zinc metal batteries (AZMBs) are attractive for stationary energy storage due to their low cost and high safety. However, parasitic side reactions and severe Zn dendrites hinder practical implementation. Here, we propose the anion/cation dehydration shielding force as an effective guideline for electrolyte engineering that prioritizes anion‐cation coordination structure. The methodology identifies 2‐ethoxyethanol solvent as optimal components, enhancing Zn ²⁺ diffusion kinetics and suppressing water activity through anion‐dominated coordination chemistry. The preferential reduction of OTF ⁻ enables fluorine‐rich solid electrolyte interphase formation with high Zn ²⁺ conductivity and excellent mechanical robustness, protecting Zn anode from side reaction and dendrite growth. As a result, the designed electrolyte enables symmetric Zn||Zn pouch cells to achieve 1500 h cycling with a remarkable cumulative capacity of 30 Ah cm ⁻² under demanding conditions (20 and 10 mAh cm ⁻² ). More importantly, Ah‐level pouch cells set extremely excellent durability milestones, maintaining 1400 cycles (4.2 months/3000 h operation) while outperforming most reported Zn metal counterparts in comparable capacity ranges.

Aqueous zinc metal batteries (AZMBs) are attractive for stationary energy storage due to their low cost and high safety. However, parasitic side reactions and severe Zn dendrites hinder practical implementation. Here, we propose the anion/cation dehydration shielding force as an effective guideline for electrolyte engineering that prioritizes anion‐cation coordination structure. The methodology identifies 2‐ethoxyethanol solvent as optimal components, enhancing Zn ²⁺ diffusion kinetics and suppressing water activity through anion‐dominated coordination chemistry. The preferential reduction of OTF ⁻ enables fluorine‐rich solid electrolyte interphase formation with high Zn ²⁺ conductivity and excellent mechanical robustness, protecting Zn anode from side reaction and dendrite growth. As a result, the designed electrolyte enables symmetric Zn||Zn pouch cells to achieve 1500 h cycling with a remarkable cumulative capacity of 30 Ah cm ⁻² under demanding conditions (20 and 10 mAh cm ⁻² ). More importantly, Ah‐level pouch cells set extremely excellent durability milestones, maintaining 1400 cycles (4.2 months/3000 h operation) while outperforming most reported Zn metal counterparts in comparable capacity ranges.

Aqueous zinc metal batteries often encounter uncontrollable failure or performance decay under thermal environments, primarily due to the severe side reactions caused by aqueous electrolytes. Here, an organic-inorganic-H₂O multiphase aqueous soggy sand electrolyte is reported to enhance high-temperature performance of aqueous zinc metal batteries. Soggy sand components form strong interactions between the heterogeneous phases, reconstructing hydrogen-bond networks and forming water-deficient solvation structures, which greatly limits water activity and improves thermal stability, eliminating parasitic reactions and inspiring a uniform Zn deposition at elevated temperatures. As a result, multiphase aqueous soggy sand electrolyte enables aqueous zinc metal batteries to achieve an operating temperature of 140 °C, a lifespan of 1700 cycles, and a current density of 8 A g⁻¹. More importantly, the application of this electrolyte allows the stable cycling of Zn metal pouch cells under continuous operation at elevated temperatures. This work paves the path towards electrolyte design that enables aqueous batteries to cycle stably under thermal environments.

The notorious dendrite growth, serious Zn corrosion and hydrogen evolution confronted by the Zn anode greatly limit the cycle life of aqueous zinc metal batteries. Here, the structure of electrical double layer (EDL) is designed by a specifically adsorbed anionic surfactant (MOA) featuring a zincophilic phosphate group and hydrophobic long alkyl chain, decreasing the activity of water on the Zn anode, effectively inhibiting the side reactions. More importantly, the reconstructed EDL by MOA exhibits a high current response characteristic, leading to the formation of a denser and thinner EDL under a high current density, which accelerates the diffusion kinetics of Zn ²⁺ and benefits the uniform Zn plating/stripping. As a result, the Zn||Zn symmetrical cells achieve an ultra‐high cumulative capacity of 60 Ah cm ⁻² , a long cycle life of 2000 h and a ultra‐high current density of 500 mA cm ⁻² . In addition, The Zn||MnO ₂ full cells demonstrate an enhanced cycling performance even under a lean electrolyte (E/C ratio = 15 µl mAh ⁻¹ ) and high cathode loading (20 mg cm ⁻² ).

Zn metal anodes in mildly acidic electrolytes usually suffer from a series of problems, including parasitic dendrite growth and severe side reactions, significantly limiting the Zn utilization efficiency and cycling life. A deep understanding of the Zn stripping/plating process is essential to obtain high-efficiency and long-life Zn metal anodes. Here, the factors affecting the Zn stripping/plating process are revealed, suggesting that thermodynamic uniformity in bulk structures promotes an orderly Zn stripping process, and a fast kinetic diffusion rate on the Zn surface facilitates uniform Zn deposition. Then, a bulk and surface co-optimized strategy for stabilizing Zn metal anodes is proposed, which is confirmed to effectively suppress the Zn dendrite growth and side reactions. Thus, the modified Zn anodes display record-breaking cycling lives of 1200 and 200 h under ultrahigh Zn utilization efficiencies of 80 and 93.5%, respectively. More importantly, using this modified Zn metal anode enables us to realize Ah-level pouch cells for continuous cycles under harsh conditions.

Rechargeable aqueous Zn metal batteries (AZMBs) are attractive for stationary energy storage due to their low cost and high safety. However, their practical application is hindered by the excessive use of zinc anodes and poor high‐temperature performance, caused by severe side reactions and dendritic growth issues. Here, an electrolyte design strategy is reported based on bidentate coordination of Zn²⁺ and solvent to tailor the solvation structure. The triethylene glycol (TEG) co‐solvent with two‐oxygen coordination sites is demonstrated to facilitate the formation of an anions‐involved solvation shell, greatly reducing the activity of coordinated H₂O molecules. The sequential reduction of OTF⁻ anions and TEG leads to the formation of an organic–inorganic bilayer SEI (hydrophobic organic layer and high ion conductivity inorganic layer), protecting Zn anodes from side reactions and dendrite growth, thus ensuring an unprecedented Zn reversibility (99.95 % over 5000 cycles at 0.5 mA cm⁻²). More importantly, the full cells of Zn||V₂O₅ exhibit a record‐high cumulative capacity (2552 mAh cm⁻²) under a lean electrolyte condition (E/C ratio=15 μl mAh⁻¹), a limited Zn supply (N/P ratio=1.9) and a high areal capacity (3.0 mAh cm⁻²).

Rechargeable aqueous Zn metal batteries (AZMBs) are attractive for stationary energy storage due to their low cost and high safety. However, their practical application is hindered by the excessive use of zinc anodes and poor high‐temperature performance, caused by severe side reactions and dendritic growth issues. Here, an electrolyte design strategy is reported based on bidentate coordination of Zn²⁺ and solvent to tailor the solvation structure. The triethylene glycol (TEG) co‐solvent with two‐oxygen coordination sites is demonstrated to facilitate the formation of an anions‐involved solvation shell, greatly reducing the activity of coordinated H₂O molecules. The sequential reduction of OTF⁻ anions and TEG leads to the formation of an organic–inorganic bilayer SEI (hydrophobic organic layer and high ion conductivity inorganic layer), protecting Zn anodes from side reactions and dendrite growth, thus ensuring an unprecedented Zn reversibility (99.95 % over 5000 cycles at 0.5 mA cm⁻²). More importantly, the full cells of Zn||V₂O₅ exhibit a record‐high cumulative capacity (2552 mAh cm⁻²) under a lean electrolyte condition (E/C ratio=15 μl mAh⁻¹), a limited Zn supply (N/P ratio=1.9) and a high areal capacity (3.0 mAh cm⁻²).