Selective Ion Transport Layer for Stable Aqueous Zinc-Ion Batteries

The limited lifespan of aqueous zinc-ion batteries (with vanadium-oxide based cathodes) is constrained by practical applications due to corrosion accelerated by vanadium ions leaching from the cathode and uneven dendrite growth on the zinc metal anode. To address these issues, the difference in size between hydrated zinc ions (4.30 angstrom) in electrolyte and vanadium ions (8.34 angstrom) is considered. Uniformly coating the MOF-801 nanoparticles (with a pore size of 6.0 angstrom) on the zinc foil formed a selective ion transport layer. The uniform zinc ion flux generated by the selective ion transport layer allows hydrated zinc ions to be transported evenly and promotes uniform zinc deposition, leading to a low overpotential (17.4 mV) and high cycle stability (1000 h) in the symmetric cell. Moreover, the selective ion transport layer, having pores smaller than vanadium ions, blocked vanadium ions from migrating toward the zinc anode, thereby reducing its corrosion and contributing to a capacity retention of 86% after 2000 cycles under full-cell conditions. This study demonstrates that the pore size of the coating layer influences the long-term stability of aqueous zinc-ion batteries and may serve as a guide when selecting interface modification materials for various metal batteries. The commercialization of aqueous zinc-ion batteries has been hindered by considerable drawbacks, such as dendritic zinc growth and cathode dissolution in mildly acidic electrolytes. Here, uniform Zn deposition, suppression of corrosion, and vanadium oxide-based cathode dissolution are achieved via a selective ion transport layer composed of MOF-801, which improved the performance and stability of aqueous zinc-ion batteries.image