Highly efficient poly(fluorene phenylene) copolymer as a new class of binder for high‐capacity silicon anode in lithium‐ion batteries

In this research, a novel approach involving the use of a fluorescent and ductile polymer for the high capacity Li‐ion battery application is reported. Poly(fluorene phenylene) copolymer as a conjugated polymer containing with lateral substituents, poly(ethylene glycol) (PEG) units, as a latent building unit for conjugation and electrolyte uptake was prepared and characterized. The synthesis process was carried out via Suzuki coupling reaction with Pd‐based catalyst by using separately obtained PEG functionalized dibromobenzene in combination with dioctylfluorene‐diboronic acid bis(1,3‐propanediol) ester. A flexible and conductive polymer was synthesized and utilized as a binder for high performance Si‐anode. The observed full capacity of cycling of silicon particles, ie, at C/3 with the capacity of 605 mAh/g after 1000^th cycle, confirms the good performance without any supplementary conductive additive. The designed and prepared binder polymer with multi‐functionality exhibits better features such as better electronic conductivity, high polarity, good mechanical strength, and adhesion.