Bioinspired Microphase-Engineered Binders for Silicon Anodes

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-Ba^{2 +} 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-Ba^{2 +} 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.