Mitigating Electrode-Level Heterogeneity Using Phosphorus Nanolayers on Graphite for Fast-Charging Batteries

Abstract

Achieving fast-charging lithium-ion batteries (LIBs) with reliable cyclability remains a significant challenge. In this study, we investigate the use of phosphorus nanolayers as a strategy to enhance the lithiation kinetics and performance of graphite-based composites without inducing lithium (Li) plating on the electrode surface, increasing the delivery capacity. In particular, operando optical microscopy reveals that during fast charging, the concentrated Li-ion flux near the graphite electrode surface impedes Li-ion permeation into the bulk, leading to nonuniform lithiation. In contrast, our designed graphite-P/C composite electrodes exhibit a well-dispersed LiC6 phase volume fraction throughout the electrodes, indicating the homogeneous lithiation of graphite. Our electrodes maintain consistent cycle retention (94.4%) and high Coulombic efficiency (>99.8%) over 1000 cycles at 1C owing to their enhanced reaction kinetics despite their relatively high capacity. Our findings highlight the potential of using phosphorus-based composites as a promising approach for achieving fast-charging LIBs with enhanced performance and safety.