Abstract
Rechargeable aqueous zinc metal-based batteries (AZMBs) have gained attention as viable options for advanced stationary energy storage, providing intrinsic safety, affordability, environment-friendliness, and competitive energy density. The widespread adoption of AZMBs critically hinges on developing durable Zn metal anodes. Despite their promise, the irreversible anodic processes stemming from water-involved side processes, such as self-corrosion and hydrogen generation, alongside uncontrollable Zn deposition and dissolution, cause dendrite growth and inactive “dead Zn”. These issues significantly impair the cycling performance and longevity of Zn anodes, severely constraining the technological implementation of AZMBs. These critical issues lie in the unregulated interfacial chemistry at the electrolyte-anode interface. Modulation of interfacial chemistry to provide a stable microenvironment and guide the occurrence of favorable Zn2+ redox processes is crucial to circumvent these problems. Zn anode modification and electrolyte engineering have demonstrated the efficiency of interfacial regulation, thereby improving cycling reversibility. Achieving such control is pivotal for realizing high-energy-density, long-lasting AZMBs, making interfacial design a key focus for future research in this field.Firstly, the improvement of zincophilicity is considered to guide the construction of Zn anode surface modification. In this section, we propose a low-coordination atom (LCA) design strategy to guide the protective layer construction for Zn anodes. Oxygen vacancies are introduced into Zn2Ti3O8 (ZTOx) to reduce the coordination numbers of Ti and Zn atoms, thereby altering electronic densities near the Fermi level of ZTOx to facilitate favorable interactions with Zn2+ ions. Experimental and theoretical findings demonstrate enhanced zincophilic sites and charge-reinforced interfaces resulting from the LCA design. Leveraging Zn anode interfacial chemistry regulation, the Zn@ZTOx electrodes present facilitated Zn2+ reduction kinetics and exceptionally planar Zn deposition. The weakened adsorption between H and ZTOx effectively prohibits side reactions. Therefore, Zn@ZTOx-based symmetric cells present outstanding cycling stability, achieving a cumulative plating capacity of 8 Ah cm-2 at 10 mA cm-2. The full-cell, coupled with an NH4V4O10 cathode, sustains an impressive specific capacity of 221.6 mAh g-1 after 3000 cycles. The LCA strategy thus expands the range of potential protective materials for Zn anodes and underscores their practicability for AZMB applications.
Next, Zn crystal plane regulation coupled with zincophilicity enhancement is explored. A preferred Zn (101) deposition is achieved using a Cu/ZnO Schottky junction (CZO) as a protective interphase. The incorporation of zincophilic Cu components and charge modulation at the heterointerfaces enhances Zn2+ plating kinetics in the CZO layer. The low mismatch between Zn and ZnO components promotes preferential Zn (101) plating. Consequently, dendrite-free Zn anodes with high durability are realized with the CZO modification. Through synergistic regulation, the CZO layer enables exceptional cell performance, achieving stable operation for 25000 cycles in Zn@CZO||I2 full cells with 80% capacity retention.
Finally, we propose an interfacial microenvironment stabilization strategy to simultaneously engineer the EDL configuration and balance pH for highly reversible Zn anodes by introducing a small amount of borax (NBO) as a bifunctional electrolyte additive. Upon dissolution, B(OH)4– anions from NBO preferentially adsorb onto Zn anode surfaces, lowering EDL capacitance by displacing free H2O from the IHP, thereby homogenizing Zn2+ flux and enabling spatially uniform Zn deposition. Critically, the dynamic equilibrium between B(OH)4– and its conjugate acid (H3BO3) establishes a robust pH buffer, mitigating electrolyte alkalization induced by parasitic hydrogen evolution and suppressing OH⁻-mediated byproduct formation. This dual regulation of EDL architecture and interfacial chemistry synergistically stabilizes Zn plating/stripping, achieving dendrite-free cycling over 3800 h in the symmetric cell at 5 mA cm-2 and a 17-fold improvement in cumulative capacity relative to baseline electrolytes. The practical viability is further evidenced in Zn||I₂ cells, where the NBO-modified electrolyte sustains 78.8% capacity retention after 9000 cycles under elevated iodine mass loading (5.5 mg cm-2).
To summarize, the investigations of interfacial microenvironment optimization have been studied from multiple dimensions in this thesis. The mechanism and material design criteria have been discussed and verified. It’s believed that the studies in this thesis are significant for further developing the commercialization of AZMBs.
| Date of Award | 2 Sept 2025 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Jian LU (Supervisor) |