Hierarchically porous carbon encapsulating sulfur as a superior cathode material for high performance lithium-sulfur batteries.
Hierarchically porous carbon encapsulating sulfur as a superior cathode material for high performance lithium-sulfur batteries.
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DOI：
10.1021/am4038728
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发表时间：
2014-01
影响因子：
9.5
通讯作者：
Guiyin Xu;B. Ding;Ping Nie;Laifa Shen;Hui Dou;Xiaogang Zhang
中科院分区：
文献类型：
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作者：
Guiyin Xu;B. Ding;Ping Nie;Laifa Shen;Hui Dou;Xiaogang Zhang
锂硫电池（li -硫电池）被认为是下一代高能电力系统中很有前途的储能设备。然而，硫的绝缘和锂多硫化物在电解液中的溶解导致硫的利用率低，循环性能差，严重阻碍了锂硫电池的快速发展。在此，我们报道了用针状纳米Mg(OH)2模板将硫包封到可溶性淀粉衍生的分层多孔碳（HPC）中。HPC具有相对较高的比表面积902.5 m(2) g（-1）和2.60 cm(3) g（-1）的大孔隙体积，因此S/HPC中硫的重量百分比高达84 wt %。当作为锂-S电池的阴极时，S/HPC复合材料在第一次循环中具有1249 mAh g（-1）的高放电容量，在1675 mA g（-1）的高电流密度下，库仑效率高达94%，在长达100次充放电循环中稳定循环。S/HPC优异的电化学性能与其独特的结构密切相关，其结构为石墨结构，具有高度发达的大孔、中孔和微孔相结合的孔隙框架。这种纳米结构可以在长时间循环过程中缩短离子和电子的传输途径。
Lithium-sulfur (Li-S) batteries are deemed to be a promising energy storage device for next-generation high energy power system. However, insulation of S and dissolution of lithium polysulfides in the electrolyte lead to low utilization of sulfur and poor cycling performance, which seriously hamper the rapid development of Li-S batteries. Herein, we reported that encapsulating sulfur into hierarchically porous carbon (HPC) derived from the soluble starch with a template of needle-like nanosized Mg(OH)2. HPC has a relatively high specific surface area of 902.5 m(2) g(-1) and large total pore volume of 2.60 cm(3) g(-1), resulting that a weight percent of sulfur in S/HPC is up to 84 wt %. When evaluated as cathodes for Li-S batteries, the S/HPC composite has a high discharge capacity of 1249 mAh g(-1) in the first cycle and a Coulombic efficiency as high as 94% with stable cycling over prolonged 100 charge/discharge cycles at a high current density of 1675 mA g(-1). The superior electrochemical performance of S/HPC is closely related to its unique structure, exhibiting the graphitic structure with a high developed porosity framework of macropores in combination with mesopores and micropores. Such nanostructure could shorten the transport pathway for both ions and electrons during prolonged cycling.