Work

Covalently Bonded Conductive Polymer Coating Si Nanoparticles for Anodes of Lithium-Ion Batteries

Year: 2026

Type: article

Abstract: Silicon anodes offer ultrahigh theoretical capacity but suffer from drastic volume changes and unstable solid-electrolyte interphases (SEIs), leading to rapid capacity fading. Here, we construct a covalently encapsulated Si anode by embedding Si nanoparticles into a formic-acid-doped PEDOT:PSS gel matrix reinforced with uniformly dispersed carbon nanotubes. At the interface, surface Si-OH groups react with PEDOT:PSS to form strong covalent bonds, providing multi-point anchoring and enhanced mechanical/electronic coupling, while the gel-like PEDOT:PSS/CNT framework builds a continuous, conductive and compliant network that buffers Si volume fluctuations and preserves electrode integrity. The optimized Si-P-5 composite delivers high initial capacity, maintains over 1200 mAh g⁻¹ after long-term cycling, and exhibits excellent rate capability, clearly outperforming conventional CMC- and PAA-based Si electrodes. SEM reveals limited thickness swelling and suppressed cracking, and XPS confirms that the SEI composition and effective thickness remain nearly unchanged upon extended cycling, indicating a structurally stable SEI formed on the encapsulation layer. This work offers a general strategy to reconcile high capacity with durable cycling in Si-based lithium-ion batteries via covalent polymer-Si interfaces and gel-type conductive scaffolds.

Source: ACS Applied Polymer Materials

DOI: 10.1021/acsapm.6c01046