Electrochemical influence of Ni atoms on Ho2O3/HoNixFe1-xO3 nanoparticles used as anodes for advanced Li-ion batteries

In this study, different ratios of Ni modified the HoFeO₃ perovskite structure to synthesize Ho₂O₃/HoNi_xFe_1-xO₃ materials (x = 0, 0.1, 0.2, and 0.3) using simple processes. The crystalline structures and elemental mapping were clarified using X-ray diffraction analysis (XRD) and transmission electron microscopy. When the ratio of Ni ions increased, no new peaks were observed in the XRD spectra, proving that Ni ions successfully replaced Fe ions in the HoFeO₃ framework. The structure of HoFeO₃ was strongly affected by ion replacement, and the electrochemical characteristics of Ho₂O₃/HoNi_xFe_1-xO₃ materials as anodes in lithium-ion batteries were improved. The incorporation of Ni atoms into the perovskite structure enhanced the electrical conductivity and generated a greater number of defects and oxygen vacancies, which are favorable for improving LIB performance. Moreover, the Ho₂O₃/HoNi_xFe_1-xO₃ sample (x = 0.3) exhibited outstanding performance with a continuously increasing capacity of over 423 mAh g⁻¹ over 100 cycles, compared with the other samples (x = 0, 0.1, and 0.2), which exhibited capacities below 300 mAh g⁻¹ at a current rate of 0.1 A g⁻¹. The enhanced electrochemical performance of Ho₂O₃/HoNi_xFe_1-xO₃ (x = 0.3) can be ascribed to the interconnections between the nanoparticles, the appropriate amount of Ni ions, and its specific structure. This study opens new applications of modified Ni atoms into perovskite materials with outstanding electrochemical performance for improved LIBs.