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

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.