Research on the influence of Li⁺ contents on the electrochemical hydrogen storage properties of BaCe_1-xLi_xO₃ solid solutions

The development of nickel-metal hydride battery anodes has long been limited by the inherent capacity decay of the anodes of the metal alloy materials. In this study, the BaCe_1-xLi_xO₃ solid solutions with controlled contents of Li⁺ ions (x = 0–0.8) were synthesized via combustion method and adopted them as the novel negative materials to offer a breakthrough in overcoming traditional performance constraints. The influences of Li⁺ contents on microstructure and electrochemical hydrogen storage performance were systematically investigated. X-ray Diffraction test (XRD) confirmed that the Li⁺ ions were successfully incorporated into the BaCeO₃ lattice and substituted at the Ce⁴⁺ sites. The grain sizes were gradually decreased from 73.5 nm (undoped) to 67.0 nm (Li_0.08). Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) results further supported the reduction of the grain sizes and proved that the Li⁺ ions had doped into the lattice of the BaCeO₃. Spectral tests showed that the Li⁺ ions induced obvious changes in the lattice structures and the concentration of oxygen vacancies. Electrochemical hydrogen storage performance tests demonstrated that the discharge capacity of BaCe_0.96Li_0.04O₃ achieved 212.7 mAh/g, representing 95.1 % improvement over the undoped sample (109.0 mAh/g), along with higher charge retention. Kinetic analysis further confirmed the superior hydrogen storage kinetic behavior of the doped samples. These results fully proved that the doping of Li⁺ ions can effectively enhance the hydrogen storage performances of BaCeO₃ materials. © 2025 Hydrogen Energy Publications LLC.