Preparation of carbon <scp> nanotubes‐hollow Co <sub>9</sub> S <sub>8</sub> </scp> composite and its use in separator modification for <scp>lithium‐sulfur</scp> battery
Bingbing Huang, Lina Jin, Xinye Qian, Jianyu Chen, Jian Cheng, Yuhe Wang
Abstract
Lithium-sulfur batteries (LSBs) have received numerous studies because of their advantages of high specific capacity, low cost of the sulfur element and so on. However, there are several obstacles restricting the commercial use of LSBs, including low conductance of sulfur, volume expansion effect of the positive sulfur electrode and serious shuttle effect of soluble lithium polysulfides. In this work, a composite of carbon nanotubes (CNTs) and hollow Co9S8 (CNTs/Co9S8) is synthesized via ZIF-67 as a template and is applied on the surface of the PE separator for LSBs. Benefited from the excellent conductance of CNTs as well as the adsorption and catalysis properties of polar hollow Co9S8, the cell with the CNTs/Co9S8 composite functional separator delivered the discharge capacity of 977.6 and remained 456 mAh g−1 after 500 loops at a current density of 0.5 C, corresponding to a low attenuation rate of only 0.1% per cycle, as well as excellent rate properties. Even at high areal mass loading of active sulfur, LSBs exhibited excellent long-term cycling stability at various current rates. In addition, the Li dendrites were remarkably restrained, which further enhanced the safety of batteries. This paper provides an effective and newfangled approach with modified separators coating composite materials of carbon species and structural sulfide to inhibit the shuttle of intermediate polysulfides and further enhance the utility of LSBs in the future.