Promoting performance of lithium–sulfur battery via in situ sulfur reduced graphite oxide coating
Promoting performance of lithium–sulfur battery via in situ sulfur reduced graphite oxide coating
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DOI：
10.1007/s12598-020-01498-y
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发表时间：
2020-07
期刊：
影响因子：
8.8
通讯作者：
Yuan Li;Xiaowen Guo;Songtong Zhang;H. Pang
中科院分区：
文献类型：
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作者：
Yuan Li;Xiaowen Guo;Songtong Zhang;H. Pang
包裹在柔性石墨烯层中的活化石墨烯/硫结构被提出作为锂硫电池的正极材料。表面涂层氧化石墨片通过一步原位硫还原法在真空下在 600°C 下还原，无需任何额外的还原剂。原位硫还原氧化石墨（RGO）涂层的高还原度将有利于高电流速率下的快速电荷转移。柔性封装的RGO结构将阻碍多硫化物的扩散并调节循环中硫的体积变化。因此，RGO 活化石墨烯 (AG)/S 电极的电化学评估显示出优异的容量、循环和倍率性能。硫负载量为 60 wt% 的 RGO–AG/S 电极在 2000 次恒电流充电/放电过程中实现了稳定的循环性能（在 1600 mA·g−1 下，每个循环的容量衰减率仅为 0.03%）。在没有电解液添加剂（如LiNO3）的情况下，平均库仑效率保持在 ~ 96%。 RGO-AG/S 电极的优异性能归因于独特的原位硫 RGO 涂层分层结构。
Activated graphene/sulfur structure sheathed in a flexible graphene layer is presented as the cathode material of lithium–sulfur battery. The surface coating graphite oxide sheets are reduced by a one-step in situ sulfur reduction method under vacuum at 600 °C without any additional reductant. The high reduction degree of in situ sulfur reduced graphite oxide (RGO) coating layer will facilitate the rapid charge transfer at high current rate. The flexible encapsulated RGO structure will retard the diffusion of polysulfides and adjust the volume change of sulfur in cycling. As a result, the electrochemical evaluation of the RGO–activated graphene (AG)/S electrode demonstrates superior capacity, cycling and rate performance. The RGO–AG/S electrode with 60 wt% sulfur loading achieves a stable cyclability over 2000 galvanostatic charge/discharge process (capacity-fade rate of only 0.03% per cycle at 1600 mA·g−1). The average Coulombic efficiency remains at ~ 96% with no electrolyte additives (such as LiNO3). The outstanding property of RGO–AG/S electrode is attributed to the distinctive in situ sulfur RGO-coated hierarchical texture.