Suppressing Vertical Displacement of Lithiated Silicon Particles in High Volumetric Capacity Battery Electrodes

Abstract Silicon is a potential high‐capacity anode material for lithium‐ion batteries. However, large volume changes in the material remains a bottleneck to its commercialization. Many works have been devoted to nanostructured composites with voids to accommodate the volume expansion. Yet, the full capability of silicon cannot be utilized, because these nanostructured electrodes have low volumetric capacities. Herein, we redesign dense silicon electrodes with three times the volumetric capacity of graphite. In situ electrochemical dilatometry reveals that the electrode thickness change is nonlinear as a function of state of charge and highly affected by the electrode composition. One key problem is the large vertical displacement of the silicon particles during lithiation, which leads to irreversible particle detachment and electrode porosity increase. Better reversibility in electrode thickness changes can be achieved by using polyimide, with a higher modulus and larger ultimate elongation, as the binder, leading to better cycle stability.