Polydopamine-coated nano-ZnO for high-performance rechargeable Zn–Ni battery

Abstract A polydopamine (PDA)-coated nanosized ZnO is prepared and employed as an anode material of Zn–Ni battery for the first time. The battery, which used the PDA-coated ZnO, displays a high specific capacity of 364.3 mA h g −1 at 1 C after 200 cycles, which is significantly stable than that of the original ZnO. The highly hydrophilic PDA layers serve as ionic transfer channels and can provide the diffusion of OH − into the inner electrode. These layers can also decrease polarization voltage and improve cycling performance. Meanwhile, a flexible and tense PDA film can retain the completeness of zinc electrode and prevent shape change. Moreover, the current distribution and zinc deposition on the surface of the electrode becomes uniform as the PDA coats the single ZnO particles.