Improved performance in micron-sized silicon anodes by in situ polymerization of acrylic acid-based slurry
The interactions between silicon particles and polymeric binders are a key factor during the course of manufacturing high-capacity Si anodes for lithium-ion batteries. Polymeric binders usually compensate for the volumetric over-changes of silicon particles, and then prevent electrode deformation while keeping the integrity of electron and ion pathways. This work explores an efficient synthesis method to directly anchor a reliable binder tightly on the surface of Si particles by in situ polymerization of an acrylic acid monomer in the mixing process of Si-based slurry. The resultant Si composite electrode possesses a highly elastic structure, which can provide a highly extensible space accommodating volume expansion/contraction of Si particles during lithiation/delithiation. Moreover, the cross-linked acrylic acid network results in a strong cohesive force between Si particles and auxiliary materials, such as conductive agent and copper foil. Accordingly, a satisfactory electrochemical performance of the Si anode can be gained, including a high initial coulombic efficiency of ∼73% and stable cycling performance (∼82% retention over 300 cycles at a current density of 4 A g−1). Such a novel and facile fabrication process represents an appealing method for manufacturing high-performance Si-based anodes using micron-sized Si particles with low cost.