Improving the Cycling Performance of Lithium-Ion Battery Si/Graphite Anodes Using a Soluble Polyimide Binder

Abstract

Herein, we improved the performance of Si/graphite (Si/C) composite anodes by introducing a highly adhesive co-polyimide (P84) binder and investigated the relationship between their electrochemical and adhesion properties using the 90° peel test and a surface and interfacial cutting analysis system. Compared to those of conventional poly(vinylidene fluoride) (PVdF)-based electrodes, the cycling performance and rate capability of P84-based Si/C anodes were improved by 47.0% (372 vs 547 mAh g^-1 after 100 cycles at a 60 mA g^-1 discharge condition) and 33.4% (359 vs 479 mAh g^-1 after 70 cycles at a 3.0 A g^-1 discharge condition), respectively. Importantly, the P84-based electrodes exhibited less pronounced morphological changes and a smaller total cell resistance after cycling than the PVdF-based ones, also showing better interlayer adhesion (<i>F</i> _mid) and interfacial adhesion to Cu current collectors (<i>F</i> _inter).