Nanopore confined anthraquinone in MOF-derived N-doped microporous carbon as stable organic cathode for lithium-ion battery

Abstract

Anthraquinone (AQ), as organic cathode material, has provided an excellent opportunity to update the preexisting energy storage technologies owing to its facile and desirable fabrication at molecular level, higher theoretical gravimetric capacities and remarkable sustainability. However, some of its pristine properties like insulation and dissolution into electrolyte of organic active materials during cycling, have been inevitable obstacles to boost its electrochemical performance. Herein, we report a rational strategy to improve lithium ion storage performance of AQ by confining nanosized amorphous AQ into zeolitic imidazolate framework-8 (ZIF-8)-derived nitrogen-doped microporous carbon scaffold (AQ@N-ZIF-8). The AQ@N-ZIF-8 cathode delivers a high reversible specific capacity of 240 mAh g−1 at current rate of 0.1 C and retains ~216 mAh g−1 after 300 cycles (remarkably low capacity fading rate of 0.08% per cycle) with coulombic efficiency up to 99%. The exceptional lithium ion storage capacity of AQ@N-ZIF-8 is mainly ascribed to the synergistic effect of high loading capacity of AQ encapsulation and nanopore confinement of AQ dissolution in carbon scaffolds, and the enhanced conductivity of the encapsulated AQ by higher contents of nitrogen dopant. Moreover, the N-ZIF-8 with micropores facilitates the fast diffusion of organic electrolyte ions.