Abstract:Lithium selenium (Li-Se) battery is considered as a potential next generation high energy density battery due to its high theoretical volume energy density (3253 mAh/cm3), high conductivity (1×10-3 S/m) and environmental friendliness. It has gradually become a research hotspot in the field of electrochemistry. However, in practical applications, Li-Se needs to overcome a series of key challenges from Se cathode, including the shuttle effect caused by soluble lithium polyselenide, the slow redox kinetics of Se cathode and the volume expansion of Se cathode during charging and discharging, which lead to the key problems of poor cycle performance and rate performance of Li-Se batteries. In this paper, a hollow tubular g-C3N4(CN-T) was synthesized, and Se was encapsulated in the hollow tubular structure of CN-T by melting diffusion. This structure not only facilitated adaptation to the volume changes during the charging and discharging process, but also effectively suppressed the shuttle effect of polyselenides, and provided the electrode with excellent ionic conductivity. The electrochemical test results showed that the discharge specific capacity of the composite reached 508.4 mAh/g in the first cycle. At the current density of 0.5C (1C=675 mAh/g), the discharge specific capacity remained at 337.4 mAh/g after 200 cycles, which was much higher than that of pure selenium cathode (247.2 mAh/g), and the coulombic efficiency remained at 99.6%, which showed that the selenium cathode modified by hollow tubular g-C3N4 had excellent cycle stability and long cycle life.