Enhancement of Li intercalation kinetics of LiFePO4 nanoparticles with mesoporous carbon

Abstract

Carbon-assisted energy storage in Li-ion batteries is a crucial topic in the era of carbon neutrality. This work reports a remarkable synergistic effect between lithium iron phosphate (LiFePO4, LFP) nanoparticles and mesoporous carbon (MC) that greatly improves the rate performance and cycle performance. The rapid capacitive effect of MC helps establish a local Li+-rich environment for LFP, enhancing the Li intercalation kinetics inside LFP nanoparticles during discharge. This synergistic effect is quantificationally evaluated using a single-particle model to compare the Li intercalation extent of LFP particles under the presence and absence of MC, which is further confirmed by high-resolution transmission electron microscopy observation, in-situ X-ray diffraction characterization and electrochemical impedance spectroscopy test. In addition, the LFP/MC composite cathode exhibits a nearly 100% capacity retention after 1,000 cycles under 1C charge and 10C discharge. Overall, the addition of MC proves to be a very simple but robust method to increase the capacity, power density and cycle life of LFP-based devices.