Enhancing the lithium storage performance of α-Ni(OH)2 with Zn2+ doping

Flower-like Zn2+ doped α-Ni(OH)2 samples were synthesized via a facile hydrothermal method. The Zn2+ doped α-Ni(OH)2 sample with Zn2+/Ni2+ molar ratio of 45% (45-ZN) exhibits much-improved cycling stability, high-rate capability, and electrochemical reaction kinetics due to the unique flower-like nanostructures and the synergetic effect between Ni2+ and Zn2+. [Display omitted] •Zn2+ doped α-Ni(OH)2 was prepared by homogeneous precipitation method.•The Zn2+ doped α-Ni(OH)2 was evaluated as an anode material for LIBs.•Zn2+ doping effectively enhanced the cycling stability and high-rate capability.•The Zn2+ doped α-Ni(OH)2 exhibited an obvious pseudocapacitive behavior. To enhance the lithium storage performance of α-Ni(OH)2, different amount of Zn2+ (with Zn2+/Ni2+ molar ratio of 0 %, 15 %, 30 %, 45 %, and 60 %, respectively) was introduced into the lattice of α-Ni(OH)2 samples by a facile hydrothermal method. The influence of Zn2+ doping on the microstructure and lithium storage performance of α-Ni(OH)2 was investigated in detail. The results demonstrate that with the increase of Zn2+/Ni2+ molar ratio, the microstructure of the as-prepared samples transforms from an urchin-like morphology to flower-like morphology, accompanied by the phase structure transforming from pure-phase α-Ni(OH)2 to mixed-phase α-Ni(OH)2/Zn(OH)2. Electrochemical characterizations reveal that Zn2+ doping can effectively enhance the lithium storage performance of α-Ni(OH)2. In particular, the Zn2+ doped α-Ni(OH)2 with Zn2+/Ni2+ molar ratio of 45 % (45-ZN) exhibits superior cycling stability (maintaining a reversible capacity of 713 mA h g−1 at a current density of 0.5 A/g after 50 cycles), outstanding high-rate capability (delivering a high specific capacity of 485 mA h g−1 at 2.0 A/g), and fast electrochemical reaction kinetics. GITT analysis demonstrates that the lithium ions diffusion coefficient of the 45-ZN varies in the range of 10−10–10−12 cm2 s−1, higher than that (10−10–10−13 cm2 s−1) of pure α-Ni(OH)2. In addition, the 45-ZN sample presents an obvious pseudocapacitance behavior during the discharging/charging process. The synergetic effect between Ni2+ and Zn2+ can account for the improved electrochemical performance of the Zn2+ doped α-Ni(OH)2. The work provides clues for the preparation and performance optimization of α-Ni(OH)2 as an anode material for lithium-ion batteries from the aspect of metal ions doping.