High Energy Aqueous Rechargeable Nickel-Zinc Battery Employing Hierarchical NiV-LDH Nanosheet-Built Microspheres on Reduced Graphene Oxide

Demand for high-capacity, long cycle life, and aqueous batteries based on abundant metals such as nickel, zinc, aluminum, and so on is rising in the energy storage field. In this study, we design a hierarchical morphology as a nanosheet-built microsphere of nickel vanadium layered double hydroxide (NiV LDH) with conductive agents graphene oxide (GO) and multiwalled carbon nanotubes (CNTs) through a low-cost hydrothermal synthesis method. The experimental results demonstrate that the graphitic structures and functional groups of the GO and CNT play an important role in controlling nucleation, growth speed, size, and finally morphology of hierarchical nanosheets. The electrochemical results indicate that the NiV LDH sample prepared by 10 wt % GO, exhibiting a nanosheet-built microsphere morphology, shows higher discharge capacity (253.9 mAh g(-1) at 0.5 A g(-1)), better cycling performance (capacity retention of 80% after 500 cycles at 4.5 A g(-1)), and excellent rate capacity (195.6 mAh g(-1) even at 4.5 A g(-1)). This enhancement can be attributed to the special architecture and stable physical structure, which is beneficial in improving hydroxyl ion diffusion and in achieving faster electrochemical kinetics and higher surface area for high-rate electrochemical reactions during charge and discharge processes. The introduced bi-metallic LDH structure is a potential candidate in cathode materials of nickel-zinc batteries for safe and high energy storage/conversion devices.