Nitrogen-doped porous biochar spheres/Mn3O4 heterostructure as an efficient sulfur host for high performance lithium-sulfur batteries

Abstract

Improving the conductivity of sulfur and enhancing the anchoring of lithium polysulfides (LiPSs) are the two key points to obtain high performance and good cyclic stability of lithium sulfur batteries (LSBs). So, a composite material with heterostructure of nitrogen-doping porous carbon spheres and Mn3O4 is designed. Nitrogen and Mn3O4 can relieve the dissolution and shuttling of polysulfides through chemisorption and reduce the loss of active substances. The induced electric field of the heterostructure can further strengthen the adsorption and transformation of lithium ions, thus accelerating the reaction process. The synergetic merits make NPCS/Mn3O4@S nanocomposites exhibit significantly better electrochemical performances than NPCS. At 1.0 C, its initial specific capacity can reach 744 mA h g−1, and can stabilize 600 cycles. When the current density is 2.0 C, the initial specific discharge capacity is 674 mA h g−1, and the reversible capacity is still 478 mA h g−1 after 200 cycles.