Optimizing lithium-ion diffusion in LiFePO4: the impact of Ti4+ doping on high-rate capability and electrochemical stability
摘要
This study aims to enhance the electrochemical performance of lithium iron phosphate (LiFePO4) cathode materials through Ti4+ ion doping strategy, in order to address the challenges of low conductivity and slow lithium-ion diffusion rates. We synthesized iron phosphate precursors with different Ti4+ doping levels using the chemical precipitation method and successfully prepared LiFePO4 material by the high-temperature solid-phase method, which improves the uniformity of ion doping. By systematically studying the effect of Ti4+ doping on material structure, morphology, and electrochemical properties, we found that Ti4+ successfully entered the LiFePO4, without affecting its morphology or lattice. This structural change had a positive impact on the electrochemical performance of the material. The discharge-specific capacities of 2% Ti4+-doped LiFePO4 samples at 0.1, 1, 5, and 10 C reached 161.0, 132.4, 105.3, and 92.6 mAh g−1, respectively, demonstrating excellent electrochemical performance. Its lithium-ion diffusion coefficient was also significantly better than that of other samples. The comprehensive analysis results from XRD, SEM, XPS, and electrochemical testing show that the appropriate amount of Ti4+ doping optimizes the diffusion path of lithium-ions and increases the charge transfer rate, thereby significantly improving the electrochemical performance of LiFePO4. This discovery not only enriches the understanding of the modification mechanism of lithium-ion battery cathode materials, but also provides important scientific basis and practical guidance for the development of high-performance lithium-ion battery cathode materials.