高吡啶氮掺杂有序介孔碳封装多硫化物实现长寿命锂硫电池

High pyridinic nitrogen-doped ordered mesoporous carbons encapsulation of polysulfides for long life lithium-sulfur batteries

锂硫电池的硫正极具有高的理论比容量(1675 mAh/g)和高的比能量(2600 Wh/kg),被认为是下一代锂电池技术。然而,单质硫以及其放电产物硫化锂导电性差和多硫化锂在电解液中溶解导致穿梭效应,严重阻碍了其商业化应用。采用硬模板法制备高比表面积和高吡啶氮掺杂的一维碳材料(NOMCs),通过物理约束和吡啶氮与多硫化锂之间强亲和力来抑制多硫化锂的穿梭效应。此材料中的石墨氮可以提高碳材料的导电性,而吡啶氮可以有效地吸附多硫化锂,抑制多硫化物在电解液中穿梭。因此,采用此材料载硫后,S@NOMCs在1C倍率下首次放电容量为853 mAh/g,充放电500次容量保持在679 mAh/g,容量衰减率仅为0.042%/圈。

The rechargeable lithium-sulfur(Li-S)batteries have been considered as promising candidates for next-generation batteries due to their high theoretical specific capacity(1675 mAh/g),high specific energy(2600 Wh/kg),and sulfur is abundant,cheap,non-toxic environmentally friendly.However,the inherently insulating nature of sulfur and the discharge products of Li2S,and the dissolution of lithium polysulphides(LiPSs)severely hampered the practical application of Li-S batteries.N-doped ordered mesoporous carbons(NOMCs)was successfully prepared with large specific surface area,high pyridinic nitrogen-doping via hard template method,in which the synergetic physical nanoconfinement effect and chemisorption restrict the LiPSs dissolution in the electrolyte.In the material,the graphite nitrogen can improve the electrical conductivity of carbon materials,and pyridine nitrogen can adsorb the lithium polysulfide,leading to inhibitting polysulfide shuttle in the electrolyte.Using the obtained carbons as sulfur hosts,S@NOMCs exhibit the first discharge capacity of 853 mAh/g and the capacity retains at 679 mAh/g after 500 cycles at 1 C,corresponding to a decay rate of 0.042%per cycle.