A water-soluble binary conductive binder for Si anode lithium ion battery

A simple yet effective polyvinyl pyrrolidone/polyaniline (PVP/PANI) co-polymer was synthesized to serve as water-soluble conductive binder for Si anode lithium ion battery (LIB) application, aiming to address its fast capacity fade and poor cycling performance. Multiple spectroscopic tests confirmed co-polymerization of individual component PVP and PANI through intermolecular hydrogen bonding and the composition of co-polymer can be easily tuned. The synthesized co-polymer is capable of greatly advancing electrochemical performance and stability of Si anode compared to conventional binders such as polyvinylidene difluoride (PVDF) and PVP and an optimal composition of PVP and PANI in terms of cell electrochemical performance was demonstrated. More detailed electrochemical and microscopic characterization reveal that considerably reduced impedance, facilitated electron transport and alleviated Si volume expansion buffer of the electrode are attributed to such improvement. Despite these merits brought by employing the co-polymer, it is also implied that a complicated trade-off exists among the electrolyte uptake, electron transport, interface resistance, and charge carriers' diffusion in the electrolyte, which is worth studying in depth in the future.