In this communication, uniform and ultrathin carbon coating on LiFePO4 (LFP) particles are performed using liquid carbon dioxide (l-CO2)-based free-meniscus coating. The uniform and conformal coverage of the carbon layer on LFP with a thickness of 3.3 nm, and a uniform distribution of carbon on the entire surface of the LFP particle are confirmed. The carbon-coated LFP (C-LFP) with a carbon content of 1.9 wt.% obtained using l-CO2-based coating exhibits a discharge capacity of 169 mAh g−1 at 0.1 C and 71 mAh g−1 at 30 C, while much lower discharge capacity of 146 mAh g−1 at 0.1 C and 17 mAh g−1 at 30 C is observed when C-LFP with an optimized carbon content of 6.0 wt.% is prepared using conventional aqueous-based coating.