Ultra-Low Dosage Lignin Binder for Practical Lithium–Sulfur Batteries

Polymeric binders stabilize lithium–sulfur (Li–S) batteries by suppressing the shuttle of lithium polysulfide (LiPS) and volume variation, but the dosage of state-of-the-art binders in sulfur cathodes (≈20 wt%) hinders the electron/ion transfer and decreases the cell-specific density. Here, a wood-inspired lignin binder is developed after modification with amino acids for practical Li–S batteries at ultra-low low dosage (2 wt%). Benefiting from strong and balanced adhesions with active/conductive/current collector materials, robust mechanical properties, and super LiPS anchoring capability, the Li–S cell delivers an initial discharge capacity of 864 mAh g −1 at 0.5 C and can readily operate 1000 cycles. Moreover, the pouch cell with high mass loading (4.75 mg cm −2 ) also delivers a high energy density of 484 Wh kg −1 . This work provides important guidance in binder design for the sulfur cathode and paves a new way for the practical application of Li–S batteries.