Cao Bokai, Huang Jiangtao, Mo Yan, Xu Chunyang, Chen Yong, Fang Haitao
School of Materials Science and Engineering , Harbin Institute of Technology , 92 West Dazhi Street , Harbin 150001 , China.
State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Provincial Key Laboratory of Research on Utilization of Si-Zr-Ti Resources, College of Materials and Chemical Engineering , Hainan University , 58 Renmin Road , Haikou 570228 , China.
ACS Appl Mater Interfaces. 2019 Apr 17;11(15):14035-14043. doi: 10.1021/acsami.8b21447. Epub 2019 Apr 4.
In order to alleviate the inferior cycle stability of the sulfur cathode, a self-assembled SnO-doped manganese silicate nanobubble (SMN) is designed as a sulfur/polysulfide host to immobilize the intermediate LiS , and nitrogen-doped carbon (N-C) is coated on SMN (SMN@C). The exquisite N-C conductive network not only provides sufficient free space for the volume expansion during the phase transition of solid sulfur into lithium sulfide but also reduces R of SMN. During cycling, the soluble polysulfide could be fastened by the silicate with an oxygen-rich functional group and heteronitrogen atoms through chemical bonding, enabling a confined shuttle effect. The synergistic effect between N-C and SMN could also effectively facilitate the interconversion between lithium polysulfides and LiS, reducing the potential barrier and accelerating the redox kinetics. With an areal sulfur loading of 2 mg/cm, the S-SMN@C cathodes demonstrate a high initial capacity of 1204 mA·h/g at 0.1 C, and an outstanding cycle stability with a capacity fading rate of 0.0277%, ranging from the 2nd cycle to the 1000th cycle at 2 C.
为了缓解硫正极较差的循环稳定性，设计了一种自组装的掺SnO的硅酸锰纳米气泡（SMN）作为硫/多硫化物主体来固定中间产物LiS ，并在SMN上包覆氮掺杂碳（N-C）（SMN@C）。精巧的N-C导电网络不仅为固态硫向硫化锂相变过程中的体积膨胀提供了足够的自由空间，还降低了SMN的电阻。在循环过程中，可溶性多硫化物可通过化学键与具有富氧官能团和杂氮原子的硅酸盐结合，实现受限的穿梭效应。N-C与SMN之间的协同效应还能有效促进多硫化锂与LiS之间的相互转化，降低势垒并加速氧化还原动力学。在面硫负载量为2 mg/cm时，S-SMN@C正极在0.1 C下表现出1204 mA·h/g的高初始容量，在2 C下从第2次循环到第1000次循环具有0.0277%的容量衰减率，展现出出色的循环稳定性。
