Enhanced electrochemical properties of Al2O3-coated LiNiPO4 cathode materials for lithium-ion batteries

Abstract

Cathode materials play a vital role in lithium-ion batteries to evaluate its performance. LiNiPO₄ is one of the attractive cathodes due to its high voltage accompanied by olivine structure. The synthesis of LiNiPO₄ cathode materials using an oxalic acid-assisted sol–gel method resulted in pristine samples, which were subsequently coated with 1 wt.% and 2 wt.% Al₂O₃ to investigate the impact on electrochemical properties. Structural analyses employing X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy revealed that the Al₂O₃-coated LiNiPO₄ samples exhibited enhanced crystallinity and smaller crystallite sizes compared to the pristine material. The initial discharge capacities were measured at 119.05 and 115.48 mAhg⁻¹ for the 1 and 2 wt.% Al₂O₃-coated samples, respectively, slightly higher than the pristine sample’s discharge capacity of 110.71 mAhg⁻¹. During cycling, the Al₂O₃-coated samples initially demonstrated superior capacity retention and cycling performance. Specifically, the 1 wt.% Al₂O₃-coated sample maintained good capacity retention throughout the cycles, indicating improved lithium-ion diffusion and structural stability. In conclusion, the study highlights that an optimal amount of Al₂O₃ coating enhances the structural properties and lithium-ion diffusion within LiNiPO₄ cathode materials, significantly improving their electrochemical performance. The findings underscore the importance of controlled coating strategies in optimizing the functionality and longevity of battery materials for advanced energy storage applications.