Department of Chemical and Biomolecular Engineering, University of California , Berkeley, California 94720, United States.
J Am Chem Soc. 2014 Mar 26;136(12):4659-63. doi: 10.1021/ja412943h. Epub 2014 Mar 14.
Lithium sulfide (Li2S) is an attractive cathode material with a high theoretical specific capacity (1166 mAh g(-1)). However, the poor cycle life and rate capability have remained significant challenges, preventing its practical application. Here, Li2S spheres with size control have been synthesized for the first time, and a CVD method for converting them into stable carbon-coated Li2S core-shell (Li2S@C) particles has been successfully employed. These Li2S@C particles with protective and conductive carbon shells show promising specific capacities and cycling performance with a high initial discharge capacity of 972 mAh g(-1) Li2S (1394 mAh g(-1) S) at the 0.2C rate. Even with no added carbon, a very high Li2S content (88 wt % Li2S) electrode composed of 98 wt % 1 μm Li2S@C spheres and 2 wt % binder shows rather stable cycling performance, and little morphology change after 400 cycles at the 0.5C rate.
硫化锂（Li2S）是一种很有吸引力的阴极材料，具有很高的理论比容量（1166 mAh g(-1)）。然而，其较差的循环寿命和倍率性能仍然是重大挑战，阻碍了其实际应用。在此，我们首次成功合成了具有尺寸控制的 Li2S 球体，并采用 CVD 方法将其转化为稳定的碳包覆 Li2S 核壳（Li2S@C）颗粒。这些具有保护性和导电性碳壳的 Li2S@C 颗粒表现出有前景的比容量和循环性能，在 0.2C 倍率下具有 972 mAh g(-1) Li2S（1394 mAh g(-1) S）的高初始放电容量。即使没有添加碳，由 98 wt % 1 μm Li2S@C 球体和 2 wt % 粘结剂组成的 Li2S 含量非常高（88 wt % Li2S）电极在 0.5C 倍率下循环 400 次后也表现出相当稳定的循环性能，且形貌变化很小。
