Polydopamine coated Si nanoparticles allow for improved mechanical and electrochemical stability

Numerous experiments suggest that the capacity decay of Silicon (Si) porous electrodes is related to the significant fracture experienced during the lithiation/de-lithiation process. In this work, modeling and surface engineering of nanosized Si is employed to synthesize nanocomposites with enhanced mechanical and electrochemical stability. Initially, a multiphysics model is applied to predict the size of Si particles that limit damage formation. The model is experimentally verified against scanning electron microscopy (SEM), which shows the fracture of Si microparticles after the first and second cycles. Particles less than 100 nm are predicted to be mechanically stable, and to further increase stability, a facile one-step in-situ polymerization process is used to synthesize Si/polydopamine (Si/DPA) nanocomposites, in which similar to 2 nm of polydopamine (DPA) uniformly coats the surface of the Si. The as-prepared electrodes exhibit higher capacity than previously reported Si/DPA composites: 2000 mAh g(-1) at similar to 700 mA g(-1), with a 66% retention after 100 cycles. A 15% higher capacity retention is observed herein for the Si/DPA nanocomposite electrode compared with the pure nano-Si electrode. The enhanced capacity retention of the nanocomposite electrode can be attributed to the engineered polymeric layer which can alter the stresses experienced by the Si surface during lithiation and enhances adhesion within the nanocomposite electrode. (C) 2021 Elsevier Ltd. All rights reserved.