Bioinspired Microphase‐Engineered Binders for Silicon Anodes

ABSTRACT Silicon anodes require binders that not only buffer volume changes but also preserve interfacial integrity. However, excessive encapsulation limits ion transport and long–term stability. Here, we develop a lipoic acid–rosin acrylate (LRA) binder via thiol–ene click chemistry. LRA exhibits high stretchability (4154%) and self–assembles into chain motifs, forming microphase arrangements in aqueous media. Incorporated into hinged–tethering phosphorylated cellulose nanocrystals (HT–PCNCs) and ionically crosslinked alginate–Ba2+ scaffolds, these motifs cluster into mesoscale domains, reminiscent of the armor plates of Phloeodes diabolicus. This hybrid structure integrates rigid backbones with deformable rosin–rich beads, enabling localized strain dissipation, self–repair, and regulated ion conduction for stable solid electrolyte interphase (SEI) formation. The elastic mosaic dispersed within HT–PCNCs/SA–Ba2+ provides mechanical robustness and ionic accessibility. The composite binder achieves a tensile strength of 308.52 MPa, fracture energy of 3288.48 MJ m−3, and ionic conductivity of 33.607 mS cm−1, while effectively suppressing interfacial cracks. Silicon electrodes deliver 83.25% capacity retention after 100 cycles, high rate capability (869.8 mAh g−1 at 3C), and long‐term durability (1798 mAh g−1 after 300 cycles), accompanied by an ultrathin (∼17 nm) LiF–rich SEI. This work highlights spatially resolved microphase engineering as a promising strategy for adaptive bio–based binders in silicon anodes.