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In this work, we compare the behavior of five kinds of high-density spherical ZnO with different surface morphology as anode materials for nickel/zinc rechargeable batteries to investigate the effects of microstructure and surface properties of ZnO on the electrochemical performance of zinc anodes. For the first time, five spherical ZnO samples with tap densities of 1.62, 2.00, 2.38, 2.83, and 3.12 g cm−3 have been successfully developed via a complexing co-precipitation method by adjusting the composition of alkaline solution and pH value. It is discovered that an enhanced volume specific capacity and more stable cycling performance can be achieved for the anode with spherical ZnO (3.12 g cm−3). Nevertheless, the as-obtained ZnO sample with higher tap density shows slightly worse high-rate performance and lower discharge capacity. Interestingly, as confirmed by the CV and Tafel polarization test, with the increase of ZnO’s tap density, the zinc anodes exhibit better reversibility and higher corrosion resistance. Consequently, the denser solid spherical structure of spherical ZnO is beneficial to effectively adjust its “dissolution-deposition” process, significantly suppressing the outward growth of zinc dendrites and enhancing the batteries’ cycling stability.

A new kind of 3D hierarchical flower-like calcium zincate is successfully achieved by a simple microemulsion method. The obtained sample is constructed with many interconnected rhomboid calcium zincate nanosheets with a thickness of 80–100 nm. When served as anode active material for zinc-based battery, the as-prepared calcium zincate delivers superior high-rate properties and improved cycling stability. At 2, 5, 10, 15, 20C, the flower-like calcium zincate shows higher specific discharge capacities of ～297.7, ～254.6, ～232.5, ～202.8 and ～170.5 mAh g−1, respectively, which are significantly higher than those of the conventional hexagon and rhomboid calcium zincate. Especially, after 400 cycles at 1C/1C, the flower-like CZO achieves a capacity retention of 90.8%, whereas the values for the hexagon and rhomboid samples are only 70.2% and 54.7%, respectively. The pronounced high-rate and cycling properties are attributable to its unique 3D hierarchical flower-like structure and small particle size, which leads to the reduced charge transfer resistance, enhanced reversibility, and improved structural stability. Therefore, the proposed 3D hierarchical flower-like calcium zincate is promising anode material with excellent high-rate and cycling properties for advanced zinc-based rechargeable batteries.

A series of Co–Al layered double hydroxide nanosheets-coated spherical nickel hydroxide with improved high-rate and cycling performance are successfully synthesized through a hydrothermal method. Scanning electron microscopy images show that Co–Al layered double hydroxide is uniformly anchored on the surface of nickel hydroxide. As cathode material for nickel-based battery, the Ni(OH)2@Co–Al layered double hydroxide(10%) displays a highest high-rate properties and cycling performance. The discharge capacities of the as-obtained Ni(OH)2@Co–Al LDH(10%) reach up to 299.7, 276.6, 247.5 and 223.2 mA h g−1 at 0.2, 1.0, 5.0 and 10.0C, respectively. After 500 cycles at 1C/1C, the Ni(OH)2@Co–Al LDH (10 wt%) delivers a high capacity retention of 87.3%. These performance improvements are ascribed to the fact that Co–Al layered double hydroxide not only forms a stable high conductive layer of β-CoOOH and γ-CoOOH, but also provides many capacity through a reversible conversion between and γ-CoOOH and CoAl LDHs, eventually leading to the improvement of the reversible property, proton diffusion and conductivity of the Ni(OH)2 cathode. Consequently, the spherical Ni(OH)2@Co–Al layered double hydroxide(10%) is a promising cathodes material for advanced nickel-based secondary batteries.

A series of Co–Al layered double hydroxide (Co–Al LDHs)@reduced graphene oxide (rGO) nanocomposite are successfully synthesized through a hydrothermal method and applied as novel cathode additives for nickel-based secondary batteries for the first time. The obtained Co–Al LDHs@rGO nanocomposite is composed of many thin nanosheets, displaying laminated structure. The effects of various Co–Al LDHs@rGO on the properties of nickel cathodes were compared and its action mechanism was further investigated. Interestingly, the Ni(OH)2 electrode added with Co–Al LDHs@rGO(10%) delivers best high-rate performances and more stable cycling stability as comparison with the pure Ni(OH)2 and Ni(OH)2+CoO electrodes. Owing to its soft and flexible structure, Co–Al LDHs@rGO(10%) is conducive to modify the electronic conductivity, proton diffusion and electrochemical reversibility of the electrode by forming a more effective and stable conductive network. Especially, Co–Al LDHs@rGO(10%) with high electrochemical activity can contribute much higher discharge capacity than the commercial CoO. Owing to its high efficiency and low cobalt content, Co–Al LDHs@rGO(10%) can be applied as an effective, cheap, and promising cathode additive for nickel-based rechargeable batteries.