Novel constructive self-healing binder for silicon anodes with high mass loading in lithium-ion batteries

Binders play an important role in preserving the mechanical stability of electrodes. Nevertheless, the typical binders normally are not stretchable to withstand a repeated large volume change, which are not suitable for high-loading silicon anodes. Herein, inspired by the natural parthenocissus, an elastic self-healing CA-PAA binder is designed for silicon anode to implement long-terms stable cycling. The multiple hydrogen bonds formed by in-situ cross-linking of water soluble citric acid (CA) and poly (acrylic acid) (PAA) can establish a reversible network for silicon particles. The CA molecule not only serves as the protecting buffer layer to release the inner stress and stabilize the solid electrolyte interface (SEI), but it can also connect with PAA to form a “inner flexibility and outer rigidity” spatial topology. Consequently, this self-healing binder enhanced silicon anode exhibits an excellent performance on accommodating the large volume change during cycling process. As expected, the silicon anode shows an impressive initial areal capacity of 6.5 mAh cm⁻², 78% capacity retention after 50 cycles with a high mass loading of 1.8 mg cm⁻², and an initial Coulombic efficiency of 89.5%. Meanwhile, the Si||NCM₈₁₁ full cell shows 74% capacity retention after 100 cycles with a reversible capacity of 1.7 mAh cm⁻².