Polydopamine grafted cross-linked polyacrylamide as robust binder for SiO/C anode toward high-stability lithium-ion battery

Abstract

Silicon-based materials, as the most promising candidates for high-performance lithium-ion batteries (LIBs), have been widely researched. However, the construction of stable electrode structure is still a challenge due to the enormous volume variation. Herein, we developed a three-dimensional (3D) binder network, polydopamine grafted cross-linked polyacrylamide (PDA-c-PAM), to build a durable anode for LIBs. The flexible PDA side chain in PDA-c-PAM offers the superior adhesion with constitutes of the electrode. And the 3D cross-linked PAM main chain endows PDA-c-PAM high stretchability to accommodate the volume variation of active material and maintain the structural integrity of electrode. As a binder for SiO/graphite (SiO/C), the fabricated SiO/C@PDA-c-PAM anode delivers an initial discharge capacity of 1350 mAh g−1 at 0.1 A g−1. At a high current density of 1 A g−1, it maintains 591 mAh g−1 after 300 cycles with a 94% capacity retention of initial capacity after activation. Coupled with commercial LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode, the full cell exhibits a high-energy density of 406 Wh kg−1 at 1 C as well as excellent stability. Thus, it is believed that designing 3D network binder is an effective approach to achieve superior cycle performance of SiO/C electrodes. We successfully synthesized a polydopamine grafted cross-linked polyacrylamide (PDA-c-PAM) polymer as binder for SiO/C anode to maintain the structural integrity and improve the cycling stability of electrode. The flexible PDA side chain in PDA-c-PAM offers the binder superior adhesion. And the 3D cross-linked PAM main chain endows the binder high stretchability. The fabricated SiO/C@PDA-c-PAM anode delivers a capacity of 591 mAh g−1 after 300 cycles at 1 A g−1. Thus, it is believed that designing 3D network binder is an effective approach to achieve superior cycle performance of SiO/C electrodes.