A Practical Zinc Metal Anode Coating Strategy Utilizing Bulk h-BN and Improved Hydrogen Redox Kinetics

Achieving high-performance aqueous zinc-ion batteries requires addressing the challenges associated with the stability of zinc metal anodes, particularly the formation of inhomogeneous zinc dendrites during cycling and unstable surface electrochemistry. This study introduces a practical method for scattering untreated bulk hexagonal boron nitride (h-BN) particles onto the zinc anode surface. During cycling, stabilized zinc fills the interstices of scattered h-BN, resulting in a more favorable (002) orientation. Consequently, zinc dendrite formation is effectively suppressed, leading to improved electrochemical stability. The zinc with scattered h-BN in a symmetric cell configuration maintains stability 10 times longer than the bare zinc symmetric cell, lasting 500 hours. Furthermore, in a full cell configuration with α-MnO₂ cathode, increased H⁺ ion activity can effectively alter the major redox kinetics of cycling due to the presence of scattered h-BN on the zinc anode. This shift in H⁺ ion activity lowers the overall redox potential, resulting in a discharge capacity retention of 96.1% for 300 cycles at a charge/discharge rate of 0.5 A g⁻¹. This study highlights the crucial role of surface modification, and the innovative use of bulk h-BN provides a practical and effective solution for improving the performance and stability.