Chickpea derived Co nanocrystal encapsulated in 3D nitrogen-doped mesoporous carbon: Pressure cooking synthetic strategy and its application in lithium-sulfur batteries.

Lithium-sulfur batteries, as a next-generation energy storage system, could deliver much higher energy density than traditional lithium-ion batteries. Although many scientific issues have been well solved, the low-cost and green synthesis of the sulfur host to realize efficient electrochemical conversions between polysulfides and sulfur needs more consideration for commercial application. Herein, Co nanocrystal encapsulated in 3D nitrogen-doped mesoporous carbon (Co@NC) is produced in gram-scale via a simple pressure-cooking strategy by using biomass as raw material. The heterogeneous catalyst was featured by an oval morphology consisting of a tremendous amount of mesopores. The Co nanocrystals in the 3D mesoporous carbon could promote the confinement and fast conversion of polysulfides; simultaneously, the 3D hollow oval morphologies could not only substantially relieve the volume change of the cathode part but also enhance the lithium-ion transportation. Consequently, a sulfur cathode within Co@NC with a sulfur loading of 2.5 mg/cm exhibits significantly improved cycle stability with a fade of 0.17% per cycle over 200 cycles. Our works prove the beneficial effects of heterogeneous catalysis in polysulfide conversion reactions and provide a green, facile, scalable, and low-cost synthetic strategy of advanced hollow carbon monolith for high-performance Li-S batteries.