Influence of Binder Adhesion Ability on the Performance of Silicon/Carbon Composite as Li-Ion Battery Anode

Abstract

A series of anodes for Li-ion battery was prepared by conventional homogenization of active material, percolator, and Na-CMC or several kinds of PVDF as a binder. Si/C composite was synthesized by embedding micro-sized silicon and synthetic battery-grade graphite in a pitch-derived carbon matrix and taken as active material. Adhesion strength of anodic film to a current collector was determined by peeling test. Thermal relaxation (120-180 °C) after calendering of PVDF-based anode slightly increases the adhesion of the film to the collector. The highest peeling strength was recorded for ultrahigh molecular weight PVDF (~0.05 N cm−1) but without advantage for cycling stability of the cell. An initial reversible capacity of 512 mAh g−1, with average capacity decay only of 0.5% per cycle, was achieved for CMC-based anode of moderate peeling strength (~0.035 N cm−1). Such good performance was attributed to a specific Si/C composite structure as well as profitable physicochemical properties of the binder.