Optimized Li+ ion diffusion pathways in unidirectional stacked lithium iron phosphate cathodes: Enhanced electrochemical performance and long-term stability

초록

In this study, we introduce an innovative approach to enhance the electrochemical performance and longevity of lithium iron phosphate (LiFePO4, LFP) cathode materials through a novel saccharide-assisted unidirectional stacking method. The inherent challenges of LFP, such as low lithium-ion diffusion and limited electrical conductivity, are addressed by leveraging saccharides as binders to achieve precise alignment of LFP particles. This method facilitates the formation of unobstructed lithium-ion pathways, significantly enhancing Li+ ion diffusion rates and cycle stability. The unmodified LFP cathode exhibited a lithium-ion diffusion coefficient (DLi+) of 7.79 x 10-12 cm2 s-1, while the S5 (sucrose 5 %) LFP cathode demonstrated a superior diffusion coefficient of 3.5 x 10-10 cm2 s-1. Additionally, the S5-LFP achieved a remarkable discharge capacity of 165.1 mAh g-1 at a 0.1C rate, compared to 147.8 mAh g-1 for the unmodified LFP. The cycle stability was also significantly improved, with the S5-LFP retaining 86.3 % of its capacity after 2,000 cycles at a 5C rate, whereas the unmodified LFP retained only 79.2 % under the same conditions. These improvements are attributed to the optimized particle alignment achieved through saccharide-assisted stacking, which enhances Li+ ion diffusion and overall electrochemical performance. Additionally, the structural integrity and electrochemical stability of the S5-LFP cathodes were thoroughly validated through a comprehensive set of characterization methods and electrochemical tests, highlighting the scalability and cost-effectiveness of this technique for battery manufacturing. This breakthrough in cathode material design offers a promising pathway for the development of highperformance, durable lithium-ion batteries, particularly for applications in electric vehicles and other demanding energy storage systems.

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