Highly adhesive and stretchable binder for silicon-based anodes in Li-ion batteries

Silicon is a promising anode material for lithium-ion batteries because of its high theoretical capacity, but Si particles are faced with huge volume change during charge/discharge process, causing a rapid capacity degradation. Among various methods designed to improve the performance of lithium-ion batteries, employing flexible binders is an effective way to sustain the bending of electrodes and the volume change of Si particles. Herein, we develop a polymer binder composed of carboxymethyl cellulose and polydopamine. This polymer composite binder is instrumental in moderating mechanical fracture of the Si anode during cycling, showing excellent adhesion force (10.8 N) and high stretchability (128.7%). The electrochemical properties (80% capacity retention after 150 cycles with an initial capacity of 2303 mAh g−1) of the Si anode show obviously improvement.