Primary particles with ultra-thin carbon layer combined with loose secondary particles to jointly promote the low-temperature performance of LiFePO4

LiFePO4/C materials with ultra-thin carbon layer primary particles and loose secondary particles were successfully synthesized using CTAB and carbon aerogel. The morphology and microstructure of LiFePO4/C were investigated in detail by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and specific surface area testing techniques. The electrochemical properties at room temperature and low temperature were evaluated by constant current charge–discharge test and electrochemical impedance spectroscopy. CTAB could effectively disperse carbon aerogel, limit the thickness of the carbon layer of the primary particles, and increase the uniformity of the carbon layer. The ultra-thin carbon layer is beneficial to the interfacial transport of Li+. Carbon aerogel could inhibit the agglomeration of primary particles, build a conductive three-dimensional bridge between primary particles, and increase the bulkiness of secondary particles and the contact area between LiFePO4/C particles and electrolyte. The combination of the two results in an excellent low-temperature performance of LiFePO4/C.