Electrochemical insertion of Ni2+ to synthesize Ca-doped β-NiV3O8 films as electrodes for sodium-ion batteries

• Published in: Ceramics international Vol. 50; no. 19; pp. 34689 - 34701
• Main Authors: Bian, Hanxiao, Xu, Haiyan, He, Yang, Ge, Qi, Li, Dongcai, Wang, Aiguo, Sun, Daosheng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Defects; Electrical properties; Electrodes; Electrodes; Films; Electrical properties; Defects
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2024.06.276

Sodium-ion batteries (SIBs) need to address inherent limitations such as low energy densities and poor cycle stability. In the paper, a novel yet safe electrochemical method has been employed to insert Ni2+ in pre-prepared films, culminating in the synthesis of Ca-doped β-NiV3O8. The high covalency of the Ni–O bond was expected to enhance the migration rate of Na+, and in turn exhibit a higher ionic conductivity. Various doping amounts of Ca2+ were applied to investigate the differences in the kinetic behavior of β-NiV3O8 film electrodes. Throughout the discharge process, the average DNa+ of Ca-doped β-NiV3O8 was calculated to be 10−13～10−12 cm2 s−1. In addition, high-resolution transmission electron microscopy (HRTEM) and ex-situ X-ray photoelectron spectroscopy (XPS) revealed the presence of oxygen defects, which assisted interfacial electron transfer. Ex-situ X-ray diffraction (XRD) revealed partial new phases (NaV3O8·xH2O and NaVO3·1.9H2O) generation alongside diverse mechanisms of sodium ion insertion/extraction. Under a lower current density with 1 M NaClO4/PC as the electrolyte, it exhibited an initial discharge capacity of 433.2 mA h m−2 at 167 mA m−2 and 96.3 % capacity retention after 100 cycles. This electrochemical method, applicable to treating film electrodes, provides a novel idea for the preparation of high-performance electrode materials for SIBs.