A Spidroin‐Inspired Hierarchical‐Structure Binder Achieves Highly Integrated Silicon‐Based Electrodes

Abstract As a promising component for next‐generation high‐energy lithium‐ion batteries, silicon‐based electrodes have attracted increasing attention by virtue of their ultrahigh theoretical specific capacities. Nevertheless, fast capacity fading posed by tremendous silicon‐based electrode volume changes during cycling remains a huge challenge before large‐scale applications. In this work, an aqueous–oil binary solution based blend (AOB) binder characterized by a spidroin‐like hierarchical structure for tolerating the huge volume changes of silicon‐based electrodes is developed. In the AOB binder, the polymer, containing hydrophobic tetrazole groups, denoted as PPB, and the water‐soluble amorphous poly(acrylic acid), mimick the β‐sheet and α‐helix structure of spidroin, respectively. Benefitting from such biomimetic design, the AOB binder enables both high tensile strength and elasticity, and strong electrode adhesion, therefore apparently stabilizing the silicon‐based electrode structure and rendering prolonged electrode cycle life. Such a strategy endows 3.3 Ah soft package cells assembled with Si/C composite anode and NCM811 cathode with a discharge specific capacity of 2.92 Ah after 700 cycles. This work marks a milestone in developing state‐of‐the‐art silicon‐based electrodes toward high‐energy‐density lithium‐battery applications.