Analyzing Electrical Performance and Thermal Coupling of Supercapacitor Assembled Using Phosphorus-Doped Porous Carbon/Graphene Composite

A novel phosphorus-doped porous carbon/graphene composite was adopted as electrode material of super-capacitor, which showed excellent electrochemical performance compared with carbon material without phosphorus heteroatom by means of cyclic voltammetry, the charge/discharge property, impedance characteristics, cycle life, and stability. The P-enriched carbons sample offered an outstanding capacitive behavior, which had specific capacitance 277 F/g and was able to withstand at a wide voltage window of 1.6 V with 90.8% performance retention after 10,000 cycles at a current density of 10 Ag-1, providing a higher energy density 26.42 Wh/kg. In addition, because the thermal effect in charge and discharge process can make the supercapacitor temperature rise rapidly in a short time and affect the electrical performance, temperature characteristic is one of the important characteristics to be considered in practical application. In this paper, a two-dimensional thermal model for commonly used coiling supercapacitor with p-doped porous carbon/graphene composite as electrode material was established, and the temperature distribution of supercapacitor and the variation of internal temperature under different conditions were analyzed by finite element method. The results show that the maximum temperature appears near the center, and the maximum temperature is related to the applied current and the number of cycles. With the increase of the current, the maximum internal temperature is increased sharply, and it is kept constant after the number of cycles reaches a certain value. Cooling measures should be taken when the maximum temperature exceeds the allowable temperature range.