Adiponitrile-Enabled Low-Solvation Strategy to Mitigate the Shuttle Effect in Lithium-Sulfur Batteries

Lithium-sulfur batteries are promising for meeting growing global energy needs and supporting sustainable development. However, the shuttle effect is a key barrier to their wide use. Reducing Li⁺ ion solvation is an effective solution. In this study, adiponitrile (ADN), featuring two highly electronegative cyano groups, forms a stable [Li(ADN)]⁺ complex that contracts the solvation shell of Li⁺. Its moderate molecular size also helps form a denser interfacial protective film on the sulfur cathode, boosting surface stability. Density functional theory (DFT) simulations show ADN's cyano groups bind strongly to Li⁺, forming stable local structures that suppress polysulfide migration and improve cycle stability. Experimentally, batteries with ADN retain 75% of initial capacity after 120 cycles at 0.2 C and have a 744 mAh g^-1 discharge capacity at 2 C. X-ray photoelectron spectroscopy (XPS) confirms ADN-Li⁺ interaction and reveals ADN's role in regulating the electrolyte's solvation environment. This work provides new insights for electrolyte design in next-generation Li-S batteries.