Biochar derived from reproducible massive biomasses presents the advantages of low cost and renewable resources.In this work aiming to solve the existing problems of the lithium-sulfur battery,sulfur@biochar (S@biochar) composite cathode materials with high capacity and good cycle performance were developed.Specifically,four kinds of biochar prepared from rice husk,miscanthus,fir,and pomelo peel were used as host matrices for the Li-S battery.Among them,the S@biochar derived from rice husk delivered the highest specific capacity and the best cycle stability according to electrochemical tests.To further optimize its performance,we prepared a highly porous rice husk derived biochar (HPRH-biochar) using silica gel as the template.The S@HPRH-biochar composite (60％ (w,mass fraction) S) enables the homogeneous dispersion of amorphous sulfur in the carbon matrix and its porous structure could effectively suppress the dissolution of the polysulfide.As a result,its electrochemical performance improved,achieving a high initial charge capacity of 1534.1 mAh· g-1 and maintaining a high capacity of 738.7 mAh· g 1 after 100 cycles at 0.2C (1C corresponds to a current density of 1675 mA·g-1).It also gives a capacity of 485.3 mAh·g 1 at 2.0C in the rate capacity test.%通过可再生生物质制备的生物炭具有成本低、环保和资源可再生的优势.本研究以分布广泛的稻谷壳、芒草、杉木和柚子皮等生物质为原料,制备了4种不同类型生物炭,然后研究了其作为锂-硫电池硫/碳正极的载体的性能.研究表明由稻谷壳制备的硫/生物炭正极材料表现出最高的比容量和最优的循环稳定性.为了进一步改善其电性能,以SiO2溶胶为模板制备了具有高孔隙率的稻谷壳生物炭,其多孔结构可有效抑制多硫化物的溶解.由此得到的硫/生物炭(硫含量为60％ (w,质量分数))材料中的硫以无定型态均匀地分散在碳载体中.该材料表现出更优异的电化学性能:在0.2C (1C=1675 mA·g-1)倍率下,首周放电容量为1534.1 mAh·g-1,循环100周后仍可保持在783.7 mAh·g-1;倍率性能测试中,在2.0C倍率下,材料的可逆容量为485.3 mAh·g-1.
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