Cost-effective hydrothermal synthesis of high-performance lithium iron phosphate via lithium sources recycling

Lithium iron phosphate (LFP) cathode material has been extensively employed in energy storage and electric vehicle applications. However, the conventional solid-state synthesis method for LFP suffers from limitations in reducing anti-site defects and optimizing Li+ migration efficiency along one-dimensional channels. As a result, it exhibits subpar electrochemical performance at high current and low temperature, which hampers its further development. In this work, a micro-nano-scaled high performance LFP cathode material was successfully synthesized using hydrothermal method, offering superior cost-effectiveness and environmental sustainability. The experiment achieved zero pollutant discharge by recycling waste liquid containing lithium. Additionally, in-situ nitrogen-doped carbon coating was applied to the LFP during the hydrothermal process. This approach not only enhanced the material's conductivity but also restrained the growth of LFP crystal cell volume, particularly along the b-axis direction of crystallization. Moreover, the synthesis of low-defect LFP with wider Li + transport channel has significantly enhanced the efficiency of Li+ extraction/insertion of the material, thereby addressing the issue of poor electrochemical performance of LFP at high-rate and low-temperature. Various electrochemical characterization methods have also confirmed that LFP synthesized from recycled lithium waste liquid exhibits significant advantages than commercial LFP, especially in terms of high-current and low-temperatures charge-discharge performance. This novel strategy provides a theoretical foundation for the industrial-scale production of LFP using low-cost hydrothermal methods.