Enhancing the Performance of a Silicon Anode by Using a New Conjugated Polymer Binder Prepared by Direct Arylation

Silicon has been considered as the next-generation anode material for Li-ion batteries due to its high capacity, but suffers from isolated conducting agents due to its large volume expansion and pulverization during cycling, causing rapid decays in performance. Using conjugated polymer binders bearing functional groups that bind Si was suggested to overcome this problem due to their electronic conductivity and enhanced mechanical properties. But conjugated polymers are generally prepared via organometallic intermediates, and are hence very difficult to purify and mass produce. Here, a novel conjugated polymeric binder based on ethylene dioxythiophene (EDOT) and phenylene (EP) was prepared using direct arylation, and then characterized. Specifically, the electrically conductive EP binder showed an enhanced adhesion to Si, and the electrode made of EP showed a capacity of 2250 mAh g(-1) at its 1st cycle and 670 mAh g(-1) at the 50th cycle, much higher than those of the electrode made of a poly(vinylidene fluoride) (PVdF) binder.