Sustainable cyanide-C60 fullerene cathode to suppress the lithium polysulfides in a lithium-sulfur battery

Lithium-Sulfur batteries (LiSB) have attracted substantial interest because of their high theoretical specific en-ergy and environmental friendliness. However, there is a problem that is known as the lithium polysulfides (LiPs) shuttle effect. Several adsorbents have been proposed experimentally and theoretically to suppress the LiPs shuttle. In particular, the use of adsorbents as a conductive material looks promising as it retains the conductivity of the sulfur cathode. Cyanide has shown very good binding towards metals and carbon materials and its functionalization onto carbon materials could be a promising material to not only facilitate the electrical con-ductivity required to design a cathode material for LiSB but also can suppress the notorious LiPs shuttle effect. Herein, to prepare a sustainable cathode material, we first investigate the functionalization of cyanide with C-60 fullerene using the B3LYP-D density functional calculations. It is found that the cyanide (CN) binds upright on a carbon of the C-60 fullerene in the most stable configuration. This sustainable cathode model was then used for an interaction study with the lithium polysulfide species at the level of B3LYP-D3(BJ)/def2-SVP method within acetone as the solvent. Results show that the C-60 and C-60-CN hybrid molecule can form covalent bonds with the S sites of the LiPs molecules. Finally, it is computationally demonstrated that the C-60 fullerene can be used as an adsorbent for the removal of cyanide and the final structure can confine the LiPs species making it a promising carbon-based material for the design of a cathode electrode for use in a LiSB.

Automated summary

Lithium-sulfur batteries have high theoretical specific energy and are environmentally friendly. However, the lithium polysulfides shuttle effect is a problem. The functionalization of cyanide onto carbon materials, particularly C-60 fullerene, shows promise in suppressing the shuttle effect and retaining conductivity. Computational studies demonstrate that C-60 and C-60-CN hybrid molecules can form covalent bonds with lithium polysulfide species, making them potential carbon-based materials for cathode electrode design.