Electrochemical performance and economic evaluation of hierarchical LiFePO₄ cathodes synthesized by a microwave-assisted hydrothermal method

This study investigates the synthesis and optimization of hierarchical lithium iron phosphate (LiFePO₄) cathode materials using a microwave-assisted hydrothermal method, aiming to enhance electrochemical performance while maintaining economic feasibility. We systematically examined the effects of polyvinylpyrrolidone (PVP) concentration, precursor molar ratios, and various carbon sources for in-situ carbon coating. An optimal PVP concentration was found as 25 wt% to promote well-defined hierarchical micro/nano structures. Citric acid served as both a chelating agent and carbon source, significantly influencing particle assembly and performance. A dual-carbon-source approach (citric acid + sucrose) improved morphology and electrochemical characteristics, with an optimal sucrose content of 15 wt%. Techno-economic analysis based on the cost-to-capacity ratio (CCR) revealed that the most cost-effective and high-performing condition was Li:Fe:P = 3:1:2 with a citric acid content 1.2 times the Fe molar ratio (CA1.2), achieving initial capacities of ~ 150 mAh g⁻¹ at 0.1C and ~ 100 mAh g⁻¹ at 1C. Additional carbon source such as glucose showed performance improvements but no linear benefits with increasing content, indicating the presence of optimal levels. These findings provide practical guidelines for developing commercially viable LiFePO₄ cathodes by balancing electrochemical efficiency and material cost.