Tailoring Three-Dimensional Cross-Linked Networks Based on Water-Soluble Polymeric Materials for Stable Silicon Anode
Seoha Nam, Yeongseok Kim, So Hyeon Kim, Hye Bin Son, Dong‐Yeob Han, Yun Ho Kim, Jeong Ho Cho, Jongmin Park, Soojin Park
Abstract
For stable battery operation of silicon (Si)-based anodes, utilizing cross-linked three-dimensional (3D) network binders has emerged as an effective strategy to mitigate significant volume fluctuations of Si particles. In the design of cross-linked network binders, careful selection of appropriate cross-linking agents is crucial to maintaining a balance between the robustness and functionality of the network. Herein, we strategically design and optimize a 3D cross-linked network binder through a comprehensive analysis of cross-linking agents. The proposed network is composed of poly(vinyl alcohol) grafted poly(acrylic acid) (PVA- g -PAA, PVgA) and aromatic diamines. PVgA is chosen as the polymer backbone owing to its high flexibility and facile synthesis using an ecofriendly water solvent. Subsequently, an aromatic diamine is employed as a cross-linker to construct a robust amide network that features a resonance-stabilized high modulus and enhanced adhesion. Comparative investigations of three cross-linkers, 2,2′-bis(trifluoromethyl)benzidine, 3,3′-oxidianiline, and 4,4′-oxybis[3-(trifluoromethyl)aniline] (TFODA), highlight the roles of the trifluoromethyl group (−CF 3 ) and the ether linkage. Consequently, PVgA cross-linked with TFODA (PVgA-TFODA), featuring both −CF 3 and −O–, establishes a well-balanced 3D network characterized by heightened elasticity and improved binding forces. The optimized Si and SiO x /graphite composite electrodes with the PVgA-TFODA binder demonstrate impressive structural stability and stable cycling. This study offers a novel perspective on designing cross-linked network binders, showcasing the benefits of a multidimensional approach considering chemical and physical interactions.