In a recent article published in Small, researchers designed a 3D nanosheet structure of ZnO/Zn(OH)2 on copper foil, which aimed to significantly enlarge the active surface area and increase the density of lithiophilic sites.
Engineering the interface to form a stable solid electrolyte interphase (SEI) rich in lithium oxides and fluorides helps to maintain stable cycling and electron/ion transport.
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Background
To improve capacity and energy storage systems in battery technologies, there is a drive in battery science to advance technology, in particular lithium metal anodes (LMAs).
Lithium metal offers a promising pathway toward next-generation batteries due to its exceptionally high theoretical specific capacity of approximately 3860 mAh g−1, and could lead to batteries with significantly increased energy densities compared to conventional lithium-ion batteries (LIBs).
Lithium metal has a low electrochemical potential and is lightweight, further underscoring its suitability. However, its practical application faces several challenges: the formation of lithium dendrites during repeated charge-discharge cycles, volumetric expansion, and associated safety concerns.
These issues lead to diminished cycle life, safety hazards, and unreliable battery performance, which limits its commercial viability.
Researchers are exploring various strategies to overcome these issues. Strategies include surface modifications of current collectors and the development of protective interfaces that can uniformly deposit lithium.
Another potential pathway is constructing functional nanostructured interfaces with a strong affinity for lithium ions (lipophilicity). Such interfaces aim to provide abundant nucleation sites, facilitate uniform lithium deposition, and suppress dendritic growth, enhancing cycle stability and safety.
The Current Study
The researchers used a scalable electrodeposition process to synthesize the ZnO/Zn(OH)2 nanosheets directly onto the copper foil. First, the copper foil was anodized in potassium hydroxide (KOH) solution to generate Cu(OH)2 nanowires.
These nanowires were then electrochemically converted by applying a cathodic current in a solution containing zinc sulfate (ZnSO4 ). This process formed a mixed nanosheet structure of Zn(OH)2 and ZnO and allowed for in-situ growth of the nanosheets with good adhesion and uniform coverage.
The structural and chemical features of the composite were characterized using several microscopy and spectroscopic techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), to analyze surface morphology, phase composition, and chemical states.
Density functional theory (DFT) was used to evaluate lithium adsorption energies on the nanosheet interface and confirmed the enhanced lithiophilicity of the fabricated layer.
Electrochemical tests involved assembling symmetric cells and half-cells, with lithium plating and stripping cycles conducted at different current densities and capacities. The stability of the layer was assessed over extended cycling, along with impedance measurements to evaluate charge transfer resistance.
Full-cell configurations with lithium iron phosphate (LiFePO4 ) cathodes were also constructed to evaluate practical applicability, focusing on capacity retention, Coulombic efficiency, and cycle life.
Results and Discussion
The electrodeposition approach successfully yielded a densely packed and highly porous ZnO/Zn(OH)2 nanosheet architecture on copper foil. A large surface area with a uniform distribution of nanosheets was observed using SEM imaging, which contributed to increased electrochemically active sites and facilitated lithium-ion transport.
DFT calculations indicated that the nanosheets had a high lithium adsorption energy, indicating strong lithiophilicity. This reduces the nucleation barrier for lithium deposition and promotes uniform nucleation across the interface.
Electrochemical analyses demonstrated that the ZOH NSs–Cu foil significantly lowered the lithium nucleation overpotential compared to plain copper foil.
This corresponded to more uniform lithium plating and minimized dendritic growth as confirmed by SEM after cycling.
Analysis also revealed the nanosheet interface supported dendrite-free lithium deposition, even under high current densities and capacities, with stable cycling exceeding 400 cycles in asymmetric cells.
The formation of a stable solid electrolyte interphase (SEI) rich in lithium oxides (Li2 O) and lithium fluorides (LiF) was integral to the improved performance. The tailored interface minimized undesirable side reactions and maintained low interfacial resistance over prolonged cycling.
Impedance spectroscopy confirmed the reduced charge transfer resistance, further emphasizing the idea that the nanosheet architecture and chemical composition foster better electron and ion transport pathways.
The full-cell tests with a LiFePO4 cathode highlighted the practical potential of this approach. The ZOH NSs–Cu foil anode maintained a high-capacity retention of over 90 % even after 350 cycles at 1 C, with nearly 100 % Coulombic efficiency, despite a low N/P ratio of approximately 1.9.
Conclusion
The study presents a novel and scalable electrodeposition strategy to fabricate ZnO/Zn(OH)2 nanosheets directly onto copper foil, creating a highly lithiophilic and nanostructured interface for lithium metal anodes.
Introducing these nanosheets enhances lithium nucleation, promotes uniform deposition, and suppresses dendritic growth, helping to extend battery lifespan and ensure safety.
The formation of a robust, lithium-rich SEI layer further contributes to the stability and low resistance of the interface, enabling durable cycling in both symmetric and full-cell configurations.
This development signals a large step forward in stabilizing lithium metal anodes, with promising implications for the development of safer, longer-lasting, and higher-capacity energy storage systems.
Journal Reference
Hyun D.-E., Choi J. C., et al. (2025). Electrodeposited ZnO/Zn(OH)2 Nanosheets as a Functional Interface for Dendrite-Free Lithium Metal. Small. DOI: 10.1002/smll.202503607, https://onlinelibrary.wiley.com/doi/10.1002/smll.202503607