Enhancing the Performance of LiFePO4 Cathodes in Li-ion Batteries: Role of Surface Coating Based on ZIF-8 Particle Size Optimization

Abstract

LiFePO₄ (LFP) cathodes are widely used in Li-ion batteries (LIBs) due to their stable voltage, environmental friendliness, abundance, and resilience. However, challenges such as insufficient electron/ion transfer and compromised structural integrity under high-rate conditions limit their performance. Surface coating has emerged as a viable strategy to enhance the stability and cycling performance of LFP cathodes; however, achieving an exceptional rate performance with an optimal coating structure remains challenging. This study was conducted to explore the feasibility of enhancing the electrochemical performance of LFP electrodes using zeolitic imidazolate framework-8 (ZIF-8) coatings, with a focus on optimizing the ZIF-8 particle size. The cycling stability and rate capability of the ZIF-8-incorporated LFP electrodes were superior compared to those of uncoated LFP. Electrodes with ZIF-8 sizes of 150 nm, 500 nm, and 1.1 μm demonstrated discharge capacities of 180, 187, and 179 mA h g⁻¹, respectively, at 0.1 C and 86, 94, and 85 mA h g⁻¹, respectively, at 10 C. Notably, the 500 nm ZIF-8 particles showed the greatest decrease in charge transfer resistance (R_ct), enhancing the overall performance and indicating a high capacity retention ratio. This study provides crucial insights into the optimal particle size of ZIF-8 for coating LFP electrodes as well as valuable guidance for enhancing LIB performances.