A novel alcohol-thermal synthesis method of calcium zincates negative electrode materials for Ni–Zn secondary batteries

• Calcium zincates were synthesized by alcohol-thermal method for the first time.
• The crystallization of as-prepared calcium zincate was well, and the particle size was small.
• The samples synthesized in the ethanol exhibited best electrochemical properties.

Calcium zincates are synthesized using ZnO and Ca(OH)2 in different alcohol solutions by the alcohol-thermal method. Through the scanning electron microscopy (SEM), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) analysis, the as-prepared samples with small particles are well-crystallized. Additionally, the morphologies of as-prepared calcium zincates are distinct in different reaction solvents such as ethanol, isopropanol and n-butanol, and the calcium zincates synthesized in the ethanol and isopropanol solutions have more excellent crystallinity. As the negative electrode materials for Ni–Zn batteries, the electrochemistry properties of calcium zincates are examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge testing techniques. The results imply that calcium zincates synthesized in the ethanol solution have lower polarization and better reversibility. The cycle performance analysis shows the as-prepared calcium zincates have a very greatly improvement in cycle life and discharge capacity compared with other methods. All of the test results show that the calcium zincates synthesized in the ethanol solution exhibit the best electrochemical performances.