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.