Design, Synthesis, and Characterization of a Novel Tetra-Block Copolymer for High-Performance Self-Healing Batteries.

Lithium-ion batteries (LIBs) have become the dominant energy storage technology due to their versatility and superior performance across diverse applications. Silicon (Si) stands out as a particularly promising high-capacity anode material for next-generation LIBs, offering a theoretical capacity nearly ten times greater than conventional graphite anodes. However, its practical implementation faces a critical challenge: the material undergoes a ~300% volume expansion during lithiation/delithiation, which causes severe mechanical stress, electrode pulverization, and rapid capacity decay. In addressing these limitations, advanced polymer binders serve as essential components for preserving the structural integrity of Si-based anodes. Notably, self-healing polymeric binders have emerged as a groundbreaking solution, capable of autonomously repairing cycle-induced damage and significantly enhancing electrode durability. The evaluation of self-healing performance is generally based on mechanical characterization methods while morphological observations by scanning electron microscopy provide direct evidence of crack closure; for electrochemically active materials, electrochemical techniques including GCD, EIS, and CV are employed to monitor recovery of functionality. In this study, a novel self-healing copolymer (PHX-23) was synthesized for Si anodes using a combination of octadecyl acrylate (ODA), methacrylic acid (MA), 2-hydroxyethyl methacrylate (HEMA), and polyethylene glycol methyl ether methacrylate (PEGMA). The copolymer was thoroughly characterized using NMR, FTIR, TGA, SEM, and EDX to confirm its chemical structure, thermal stability, and morphology. Electrochemical evaluation revealed that the PHX-23 binder markedly improves cycling stability, sustaining a reversible capacity of 427 mAh g