A binder-free lithium-sulfur battery cathode using three-dimensional porous g-C3N4 nanoflakes as sulfur host displaying high binding energies with lithium polysulfides

• Published in: Journal of alloys and compounds Vol. 881; p. 160629
• Main Authors: Zhang, Haikuo, Lin, Xirong, Li, Jinjin, Han, Tianli, Zhu, Mengfei, Xu, Xiaoyong, Hu, Chaoquan, Liu, Jinyun
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10.11.2021; Elsevier BV
• Subjects: Binder-free; Binding energy; Capacity; Carbon nitride; Cathodes; Composite; Density functional theory; Graphene; Lithium sulfur batteries; Polysulfides; Secondary battery; Sulfur; Secondary battery; Composite; Binder-free; Capacity; Binding energy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.160629

•A binder-free composite cathode is developed for Li-S batteries.•Stable capacity and recoverable rate-performance are achieved.•Density functional theory calculations show the composite has large binding energies with polysulfides.•Three-dimensional composite facilitates ion diffusion and electron transport. [Display omitted] A binder-free porous graphene like-C3N4 nanoflakes/carbon cloth/sulfur lithium-sulfur battery cathode prepared through a thermal polymerization method is presented. On the basis of the density functional theory calculations on the bonds between g-C3N4 and lithium polysulfides including Li2S4, Li2S6 and Li2S8, it is found the cathode possesses robust binding energies towards polysulfides and an improved conductivity, which would enable a strong suppression for the transfer of the lithium polysulfides. The prepared porous binder-free cathode exhibits a high capacity of 892 mAh g−1 after cycling 250 times at 0.2 C and a well-recoverable rate-performance, which indicates a good potential to construct high-performance lithium-sulfur batteries for practical applications.