Activating redox kinetics of polysulfides within edge-rich nitrogen doped porous interconnected carbon nanosphere. (15th June 2023) - Pan, Junda
Graphical abstract: An edge-rich nitrogen doped micro-mesoporous interconnected carbon nanosphere (N-PCS) was rationally designed and prepared as an electrocatalyst for LSBs. The N-PCS with ultra-high content of edge N atom doping and unique pore structure can effectively bind LiPSs and greatly accelerate their reduction kinetics. As a result, the S/N-PCS operated continuously for more than 1000 cycles at 1.0 C with an ultra-low capacity decay rate (0.04% per cycle), and even provided a high area specific capacity of 5.27 mAh cm −2 at a high sulfur loading of 5.49 mg cm −2 . Highlights: We presented an edge-rich nitrogen-doped porous carbon nanospheres with an interconnection structure (N-PCS). N-PCS possessed ideal structural framework, sophisticated chemical composition and brilliant physical electric-field effect. Abundant edge doped-nitrogen substances acted as chemisorption centers and catalytic active sites for rapid conversion of LiPSs. The S/N-PCS operated excellent electrochemical performance even under high sulfur loading and lean electrolyte/sulfur ratio conditions. Abstract: Theoretically, lithium-sulfur batteries (LSBs) are highly competitive in achieving high energy density storage systems. However, the shuttle effect of polysulfides (LiPSs) and sluggish redox kinetics have severely hampered the commercialization of LSBs. Although a number of catalysts have been applied to solve these problems, their preparation processes and costs are hardly compatible with universalization. Herein, we presented an edge-rich nitrogen-doped porous carbon nanospheres with an interconnection structure (N-PCS) as sulfur redox host, of which mesoporous voids accommodated sulfur to achieve homogenization of sulfur, microporous spaces acted as physical confinement to bind the LiPSs. The interconnected carbon nanosphere could be regarded as penetrated conductive network, which greatly shorten the diffusion distance of Li + and accelerated carrier diffusion. Moreover, abundant edge doped-nitrogen substances introduced a large number of chemisorption centers and catalytic active sites, realizing the strong adsorption and rapid conversion of LiPSs within the N-PCS skeleton. As a result, the S/N-PCS cathode had a first discharge specific capacity of 755 mAh g −1 at 1.0 C and operated enduringly with an ultra-low capacity decay rate (0.04% per cycle) up to 1000 cycles. Not to be outdone, the S/N-PCS cathode provided area specific capacities of up to 4.76 and 5.27 mAh cm −2 at elevated sulfur loadings of 4.31 and 5.49 mg cm −2 . This work not only provides a low-cost improvement strategy, but also expands new research ideas for the development of high-performance LSBs cathodes.