Novel conductive binder for high-performance silicon anodes in lithium ion batteries

A novel polymer is designed to serve as the conductive binder for high-capacity silicon anodes in lithium ion batteries (LIBs), aiming to address fast capacity fade and poor cycle life of silicon anodes caused by large volume change during repeated cycles. Abundant carboxyl groups in the polymer chain can effectively enhance the binding force to Si nanoparticles (NPs) and the n-type polyfluorene backbones of the polymer significantly promote the electronic conductivity under the reducing environment for anodes, dual-features of which can maintain electronic integrity during lithiation/delithiation cycles. Notably, the polymer can react with the polar groups on the surface of Si NPs to form strong chemical bonds, thus truly maintaining the electrode mechanical integrity and good electronic conductivity after repeated charge/discharge process. The as-assembled batteries based on the polymer without any conductive additive exhibit a high reversible capacity (2806 mA h g−1 at 420 mA g−1) and good cycle stability (85.2% retention of the initial capacity) after 100 cycles.