A multifunctional electronic-ionic conductive polymeric binder for high-stability and conductive additive-free silicon anodes

The structural instability and sluggish kinetics of silicon (Si) anodes primarily arise from their substantial volume variation and poor electron/ion conductivity, which seriously hinder their practical applicability. Herein, we designed an electronic–ionic dual conductivity polymeric binder with tailored mechanical properties for conductive additive–free silicon nanoparticle (SiNP) anodes with high cyclability. On the one hand, poly(3,4–ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in the binder system provides high electronic conductivity, while the ether oxide in poly(ethylene oxide) (PEO) and lithium carboxylate in lithiated poly(acrylic acid) (PAALi) provide the fast pathway for lithium–ion (Li+) transportation. On the other hand, soft PEO and hard PAALi synergistically modulate the mechanical properties of the overall binder system. The designed binder named as PPPLi–721 enables the high structure integrity and fast electrode kinetics of the conductive additive–free SiNP electrodes during cycling. Thus, the Si@PPPLi–721 electrode retains a high capacity of 1062 mAh g⁻1 even at a high current density of 8 A g⁻1 and demonstrates stable cycling with an areal capacity above 3 mAh cm⁻2. Remarkably, the LiNi0.8Co0.1Mn0.1O2 (NCM811)/Si@PPPLi–721 full cell achieves a maximum accessible areal capacity of 1.37 mAh cm⁻2. This research provides a transferable strategy for the structural design of multifunctional binders for the development of high–performance Li+ batteries (LIBs).