Preparation of Zn–Al–Gd-hydrotalcite and performance in zinc-nickel batteries

Abstract

In this study, Zn–Al-Gd layered double hydroxides (LDHs) were synthesized via a hydrothermal method and investigated as possible negative electrode materials for zinc-nickel batteries. X-ray diffraction analysis and scanning electron microscopy images showed that the as-prepared samples were well crystallized with a hexagonal structure. The electrochemical performance was investigated for Zn–Al-LDHs and Zn–Al-Gd-LDHs with different Zn/Al/Gd molar ratios by cyclic voltammetry, Tafel polarization, electrochemical impedance spectroscopy, galvanostatic charge–discharge measurement, and cycle charge–discharge analysis. The initial discharge capacity reached 416.7 mAh g−1 for the Zn–Al-LDHs electrode and the discharge capacity decreased to 347.3 mAh g−1 after 150 cycles, with a cycle retention rate of 83.34 %. Compared with Zn–Al-LDHs, Zn–Al-Gd-LDHs with different Zn/Al/Gd molar ratios had higher discharge capacities and more stable cycling performance, especially the sample with Zn/Al/Gd = 3:0.8:0.2 (molar ratio). After 150 cycles, the retention rate for the sample with Zn/Al/Gd = 3:0.8:0.2 (molar ratio) was 88.73 %. Zn–Al-Gd-LDHs with a high rate capability can meet the needs of high-storage applications.