Mesocarbon microbead based dual-carbon batteries towards low cost energy storage devices

Abstract

Recently, the low cost energy devices with high energy density and high power density are becoming more and more important in the field of electric vehicles. In this work, the electrochemical intercalation/deintercalation behaviors of PF6ˉ into graphitic mesocarbon microbead (MCMB) cathode are investigated in the electrolyte of 1 M LiPF6 in the mixed solvent of ethylmethyl carbonate and sulfolane. The charge storage mechanisms related to surface-limited capacitive and diffusion-controlled intercalation capacity are also studied by cyclic voltammetry measurements, which indicates that both the intercalation reaction and the capacitive reaction contribute to the overall capacity. Furthermore, dual-carbon batteries comprising MCMB cathode and pre-lithiated MCMB anode are unprecedentedly demonstrated in the form of aluminum pouch cells with laminated structure and exhibit an encouraging energy density of 47.9 Wh kg−1 at the power density of 583.6 W kg−1 based on the overall mass of the battery. Finally, electrochemical impedance spectroscopy is used to differentiate the resistance variation of MCMB cathode and MCMB anode before and after 3000 cycles. The continuous intercalation/deintercalation of PF6ˉ into MCMB cathode lead to the exfoliation of the active material and the increase of internal resistance.