ZIF-L Derived Nitrogen-doped Carbon Nanosheets/Carbon Cloth Self-supported Electrode for Lithium-selenium Battery

Selenium (Se) is considered as a new generation energy storage material of lithium-selenium (Li-Se) battery due to its high volume specific capacity (3253 mAh center dot cm(-3)) and high electronic conductivity (1x10(-5) S center dot m(-1)). To address the problems of volume expansion, fast capacity decay, and low utilization of active materials during its charging-discharging process, a ZIF-L derived nitrogen-doped nanosheets/selenium (Se@NC/CC) flexible self-supported composite electrode is designed in this study for lithium-selenium battery by growing two-dimensional zinc-based metallic organic framework (ZIF-L) on carbon cloth (CC). The rich microporous structure in the nitrogen-doped carbon nanosheets can effectively alleviate the volume expansion during the reaction process, and the doping of heteroatoms N helps to adsorb Li2Se and reduce the loss of active substances. In particular, it is found that there is strong chemical bonding between Se and C in the Se@NC/CC electrode, which also helps to reduce the loss of active materials and improve the performance. Electrochemical results show that the initial discharge specific capacity of the Se@NC/CC electrode is 574 mAh center dot g(-1) at a current density of 0.5C (1.0C=675 mAh center dot g(-1)), demonstrating a high initial discharge specific capacity. At a current density of 2.0C, the initial discharge specific capacity is 453.3 mAh center dot g(-1), which maintains at 406.2 mAh center dot g(-1) after cycling for 500 cycles and it also displays excellent rate performance compared to literature. Such a flexible self-supported selenium cathode designed in this study provides a new research route on the design of selenium host materials for advanced alkali metal-selenium batteries.