Co-operation of hydrogen bonds and dynamic covalent bonds enables an energy-dissipative crosslinked binder for silicon-based anodes

Abstract

Although silicon (Si) possesses a desirable super-high theoretical capacity, a serious capacity decline caused by the inevitable volume expansion of Si hinders its practical application. To maintain the structural stability of the Si anode and alleviate the adverse effect of volume expansion, herein, a cross-linked energy-dissipative binder (TCB) enabled by the cooperation of graded hydrogen bonds and dynamic covalent bonds is proposed. Hydrogen bonds act as sacrificial bonds to be dissociated firstly from the weakest to the strongest ones when undertaking the stress produced by Si volume expansion, imparting the binder energy-dissipation property. Meanwhile, the dynamic covalent bonds build a robust cross-linked network to sustain the strain resistance and maintain the structural stability of the Si anode. Consequently, after 150 cycles at 0.5C, the Si-TCB anode can offer a high capacity of 2053.6 mA h g⁻¹. Commercial silicon/graphite (Si/C) anodes with the TCB binder present excellent rate performance and can function steadily over 300 cycles at 1C with a restricted capacity of 500 mA h g⁻¹. Additionally, the Si/C||LiFePO₄ full-cell incorporating the TCB binder exhibits a favorable cyclability of 0.19% capacity loss for each cycle.