Tri-functional binder: Graded hydrogen bonding as a bridge to endow SiO anodes self-healing and high cycling stability

The volume change of the SiO anode seriously affects the structural integrity and cycling stability of the electrode. To address this issue, a binder called TA-IA is proposed, which features strong adhesion capabilities, high mechanical strength, and elastic recovery functionality, thereby enhancing the cycle life of the SiO anode. This tri-functional binder (TA-IA) is synthesized by covalently cross-linking tapioca starch (TA) with itaconic acid (IA) molecules, forming a highly stretchable and strongly adherent three-dimensional (3D) network. This network effectively mitigates the impact of volume changes on SiO particles. Additionally, the cross-linked -O=C-O- bonds in the TA-IA binder establish more substantial graded hydrogen bond sites with SiO-OH, enhancing self-healing ability. The experimental results demonstrate that the SiO anode with TA-IA binder exhibits excellent cycling stability, maintaining a capacity of 992.2 mAh g⁻¹ at 2 A g⁻¹ after 400 cycles. Even under a high mass loading of 3 mg cm⁻², the TA-IA/SiO electrode maintains stable cycling after 300 cycles at 1 A g⁻¹. Ultimately, the assembled TA-IA/SiO||PVDF/NCM811 full cell retains an impressive retention ratio of 98.7% after 100 cycles at 1 C, highlighting its remarkable cycling stability and practicality. This work provides valuable insights for designing functional starch-based binders for high-performance SiO electrodes.