明胶基氮掺杂大孔容多孔炭的制备及在锂硫电池硫正极中的应用

Preparation of gelatin-derived nitrogen-doped large pore volume porous carbons as sulfur hosts for lithium-sulfur batteries

以富含氨基酸的明胶为前驱体、二氧化硅和冰为双模板,通过冷冻干燥法制备得到了高氮掺杂的大孔容多孔炭材料(GPC),将其作为正极硫载体。通过调整模板的配比,调控了GPC材料的孔道结构和孔容。多硫化锂吸附实验表明,氮掺杂的GPC材料对多硫化锂具有较强的化学吸附能力。电化学测试结果表明,氮掺杂有利于加快硫的还原反应动力学,从而抑制多硫化锂的穿梭效应。同时,GPC的孔容越大,硫正极的循环稳定性越优。所制具有7.00%的高氮含量和2.98 cm^3 g^−1孔容的GPC材料,不仅可以实现78.4%的高硫含量,而且还获得了较高的硫利用率。同时,所制GPC-S正极在0.1 C倍率下,初始放电比容量高达1384 mAh g^−1,循环100次后比容量仍达到608 mAh g^−1。

Gelatin-derived N-doped porous carbons(GPCs)with a large pore volume were synthesized by a method combining templating,freeze-drying and carbonization,using amino acid rich gelatin as the carbon and nitrogen sources,and silica sol and ice as the templates.The pore volume of the GPCs was regulated by adjusting the mass ratio of the silica sol to ice.Lithium polysulfide(LiPS)adsorption experiments show that the materials have a strong chemisorption for LiPSs.Electrochemical measurements show that N-doping accelerates the sulfur reduction kinetics and inhibits the shuttling of LiPSs.In addition,the larger the pore volume of the GPC,the better the cycling stability of the sulfur cathode.A highly N-doped(7.00%)GPC with a pore volume of 2.98 cm^3 g^−1 could adsorb a high sulfur content of 78.4%and had a high sulfur utilization rate.Its composite with sulfur as a cathode material gave a high initial specific capacity of 1384 mAh g^−1 at 0.1 C,which dropped to 608 mAh g^−1 after 100 cycles.