Multifunctional Cyclized\nPolyacrylonitrile (cPAN)\nas a Coating for Sb-Based Anodes in Sodium-Ion Batteries

Conversion electrodes, such as antimony (Sb), are high\nenergy density\nelectrode materials for sodium-ion batteries (NIBs). These materials\nare limited in their performance due to the mechanical instability\nof these systems resulting from volume expansion of the material during\ncycling. Stabilizing conversion materials using a conductive polymer\nbinder (CPB) protective layer is an effective way to enhance the performance\nof these materials. There is, however, a lack of a clear understanding\nof how CPBs affect the (de)insertion and surface chemistry of these\nsystems. Herein, we report the systematic investigation of the effects\non Na-ion (de)insertion chemistry of a cyclized-polyacrylonitrile\n(cPAN) layer on Sb-based conversion electrodes in NIBS. Through electrochemical\ncharacterization, it was determined that the inclusion of a cPAN layer\nincreases the achievable capacity of the electrode system due to the\nstorage of Na ions by the cPAN layer and facilitates Na-ion transport\nto the Sb active material at early cycles by reducing the charge transfer\nresistance of the ensemble electrode.