Enhanced electrolyte wetting by sodium cholate towards boosting performance of LiFePO₄ dense-thick electrodes

Densifying and thickening electrodes is an effective strategy for improving battery energy density. This strategy necessitates particular attention to electrolyte wetting across the surface into the pore networks of dense-thick electrodes, as the completeness of pore filling with electrolytes critically impacts their performance. Herein, we propose incorporating sodium cholate (SC) into electrodes to enhance electrolyte wetting and promote electrolyte infiltration. The efficacy of this approach is evaluated by using dense-thick LiFePO₄ (LFP)/single-walled carbon nanotube (SWCNT) electrodes that are prepared by vacuum filtration process. The SC adsorbed within LFP/SWCNT electrodes promotes electrolyte infiltration, which facilitates lithium-ion transport, increases the solid/electrolyte interfacial area, and consequently boosts the rate capacity. Surprisingly, the incorporated SC effectively stabilizes the cathode/electrolyte interphase, thereby extending the cycle life of LFP/SWCNT electrodes. The adsorbed SC increases the capacity of 40 mg/cm² LFP/SWCNT electrode at 0.5 C from 98 mAh/g to 139 mAh/g, and improves capacity retention rate from 60.3 % to 98.7 % after 500 cycles. Furthermore, the SC wetting-enhancement approach has excellent applicability to conventional slurry-cast LFP electrodes, as demonstrated by significant performance improvements after adding 1 wt% SC to slurry-cast 200 µm-thick LFP/carbon black (CB) electrodes. This study provides a valuable approach for advancing the practical deployment of dense-thick electrodes in high-energy-density lithium-ion batteries.