A reactive eco–vegetable oil–based binder for high–performance lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have received considerable attention due to their high theoretical specific capacity (1675 mAh g–1) and environmental friendliness. Whereas, the development of Li–S batteries has been limited by the shuttle effect and volume expansion. Binders play a key role to alleviate the above issues as an essential part of the Li–S batteries. However, there are few studies about the application of vegetable oils for preparing Li–S batteries binders. Herein, a cross–linked reactive castor oil–based binder (CAB) initiated by UV light is reported. The robust covalent cross–linking network relieves the volume expansion and ensures the stability of the electrode while numerous polar groups such as –CO and –NH– suppress the shuttle effect by immobilizing polysulfides. Therefore, the Li–S batteries with CAB binder exhibits excellent cycling stability (an initial discharge specific capacity of 1037 mAh g–1, 510 mAh g–1 after 500 cycles), and a remarkable areal capacity of 3.8 mAh cm–2 after 70 cycles even though a high sulfur loading (5.3 mg cm–2). The reactive eco–vegetable oil–based binder confirms the feasibility of UV–curable CAB as the binder for Li–S batteries and contributes to the development of efficient vegetable oil–based, reactive binders with the improved mechanical properties.