Novel copper-doped ceric dioxide interface layer enables dendrite-free zinc batteries with exceptional lifespan

Researchers from Fuzhou University have developed a revolutionary surface engineering strategy that dramatically enhances the performance and longevity of aqueous zinc metal batteries (ZMBs), a promising technology for grid-scale energy storage. By precisely doping copper atoms into a ceric dioxide (CeO₂) artificial interface layer, the team achieved over 1,600 hours of stable, dendrite-free cycling—representing more than a tenfold improvement over conventional zinc anodes.

The study, published in Frontiers in Energy, addresses the fundamental bottleneck limiting ZMB commercialization: the formation of destructive zinc dendrites and parasitic side reactions caused by sluggish zinc-ion desolvation kinetics at the electrode-electrolyte interface.

Research Background Aqueous zinc metal batteries have attracted global attention as a safe, low-cost, and environmentally friendly alternative to lithium-ion systems for renewable energy storage. However, their practical application has been severely hampered by the uncontrolled growth of zinc dendrites during charge-discharge cycles, which can puncture battery separators and cause short circuits. Additionally, corrosion and side reactions with water molecules degrade performance and shorten battery lifespan. These issues stem primarily from the slow removal of water molecules from hydrated zinc ions [Zn(H₂O)₆]²⁺ at the anode surface—a process known as desolvation.

Prior approaches using artificial protective layers faced a critical trade-off: layers with strong zinc affinity could guide uniform deposition but hindered ion migration, while weakly adsorbing layers allowed fast ion transport but failed to prevent dendrite formation.

Research Content The Fuzhou University team, led by corresponding authors Yinze Zuo, Wei Yan, and Jiujun Zhang, pioneered a "surface electron reconfiguration" approach to overcome this limitation. Through high-temperature calcination, they successfully incorporated copper atoms into the CeO₂ lattice, creating a Cu₂Ce₇Ox nanosheet coating approximately 300 nanometers thick on zinc foil.

Density functional theory calculations revealed that copper doping induces unusual s-p-d orbital hybridization, triggering electron rearrangement that disperses electron density between copper and oxygen atoms. This electronic structure modulation precisely tunes the interfacial properties: reducing the adsorption energy from an excessive −3.21 eV (pure CeO₂) to an optimal −1.88 eV, while increasing migration energy to 0.91 eV—effectively inhibiting uncontrolled two-dimensional ion diffusion that leads to dendrite formation.

Research Results The Cu₂Ce₇Ox interface delivered exceptional electrochemical performance across multiple battery configurations:

• Symmetric Cells: Achieved stable cycling for over 1,600 hours at 1 mA/cm² with an ultralow overpotential of just 24 mV—a stark contrast to bare zinc anodes that failed after only 90 hours.
• Asymmetric Cells: Demonstrated a cycle life exceeding 2,500 hours with an average Coulombic efficiency of 99.9%, indicating highly reversible zinc deposition and stripping.
• Full Battery Performance: When paired with a MnO₂ cathode, the Cu₂Ce₇Ox@Zn/MnO₂ full cell retained 88.9% of its initial capacity after 800 cycles at 1 A/g, while maintaining superior rate capability (138.9 mAh/g even at 2 A/g) and self-discharge characteristics (98.9% capacity retention after 24 hours).
• Low-Temperature Operation: The technology proved effective at 0°C, delivering 92.9 mAh/g after 500 cycles—critical for applications in cold climates.

Comprehensive characterization confirmed that the interface layer significantly suppressed corrosion and hydrogen evolution reactions. In situ optical microscopy showed flat, uniform zinc deposition without protrusions, while immersion tests revealed complete inhibition of zinc hydroxide sulfate formation after seven days in electrolyte.

Research Significance This work demonstrates that precise control of electronic structure through cationic doping can fundamentally resolve the adsorption-migration trade-off that has plagued zinc battery interfaces. The Cu₂Ce₇Ox interlayer not only accelerates Zn²⁺ desolvation but also guides uniform three-dimensional nucleation, effectively eliminating dendrite formation while maintaining fast reaction kinetics."

The strategy provides a universal design principle for artificial interlayers in metal battery systems, offering a pathway toward safer, longer-lasting, and more efficient energy storage solutions for renewable grid integration and electric vehicles. The simple, scalable fabrication process further enhances its commercial viability.