Optimization design of carbon additive in cathodes and regulation mechanism of capacitor battery performance

Li-ion batteries exhibit high energy density, while supercapacitors demonstrate high power density and long cycle life. A series of unimpeachable studies show that adding capacitive carbon to cathodes can construct a new type of capacitor batteries to greatly improve the rate capability and cycle life of Li-ion batteries without significantly reducing the energy density, so as to realize the technology integration of capacitor and battery. In this paper, with the aim of preparing high performance cathode material for capacitor battery, the cathode material with high speed electron, ion channels and high specific power and capacity is constructed by controlling the surface functional group of carbon additives, particle size and the characteristics of ion electron transport. The results show that although the presence of oxygen-containing functional groups on the surface of capacitive carbon can improve the capacity of capacitive carbon itself, it has adverse effects on the rate capability of cathode material of Li-ion batteries, and the more the oxygen content, the greater the internal resistance of the hybrid electrode, and the worse the electrochemical stability of the electrolyte. The size matching between the capacitive carbon particles and the cathode material can not only ensure good electron close contact and vibration density, but also the appropriate size of carbon additives can alleviate the volume expansion of the cathode electrode to enhance the cycle stability.