Highly Stretchable Polymer Binder Engineered with Polysaccharides for Silicon Microparticles as High-Performance Anodes.

Silicon has been considered as a promising anode material for lithium-ion batteries owing to its extraordinarily high capacity. However, the huge volume expansion during cycling results in severe pulverization and disintegration of active materials, especially when the particle size is in microscale. This challenge can be addressed by highly stretchable polymer binders engineered with helical polysaccharides. The elaborately designed binder presents excellent stretchability and adhesive property, which can buffer the strain caused by the large volume change and coalesce the pulverized silicon fragments without disintegration. As a result, the microsized silicon electrode exhibits high initial Coulombic efficiency of 91.8 % and excellent cycling stability for 300 cycles. Importantly, when paired with a commercial LiCoO2 cathode, the full cell manifests a high areal capacity of 3.02 mAh cm-2 and superior stability for 100 cycles. Our contribution paves the way to the practical application of microsized silicon for lithium-ion batteries.