Light-weight g-C3N4/carbon hybrid cages as conductive and polar hosts to construct core-shell structured S@g-C3N4/carbon spheres with enhanced Li ion-storage performance

Abstract To compete with commercial lithium-ion batteries, light-weight, conductive and polar hosts with high sulfur loading content are required for lithium-sulfur batteries. Herein, light-weight g-C3N4/carbon hybrid cages as sulfur host have been designed and fabricated using NaCl and nanosized manganese compounds (MnO and MnCN2) as templates via a facile and controllable aerosol-pyrolysis route. The porous g-C3N4/carbon shell is designed to facilitate fast electron/Li ion transports and impede lithium polysulfide shuttle simultaneously. The cage cavity created by the NaCl template is designed to enhance sulfur loading content. Electrochemical evaluations demonstrate excellent cyclic capacity and stability of core-shell structured S@g-C3N4/carbon cathode endowed by the versatile structural and chemical advantages of the g-C3N4/carbon host cages. The first-cycle discharge capacities reach 1517 and 1240 mAh g−1 at 0.2 C and 1 C, respectively, demonstrating efficient utilization of the loaded sulfur. The capacity fading rate of each cycle is 0.09% during 400 discharge/charge cycles (from the second cycle) at 1 C. These light-weight, conductive and polar g-C3N4/carbon cages have been demonstrated to be suitable hosts to load sulfur as high-performance cathode for lithium-sulfur batteries.