The mechanism of carbon-addition-enhanced electrochemical kinetics

The lithiation process of carbon coated silicon nanoparticles is simulated using molecular dynamics simulation in order to unveil the kinetics mechanism. The simulation shows that lithium ions are activated by charged carbon coating under coulombic and Van der Waals force. The lithiation reaction is determined by the activation degree of Li ions which varies on the carbon density, not by the diffusion amount of Li ions. It can interpret well the abnormal phenomenon that bigger diffusion flux of lithium ions does not bring about faster lithiation reaction rate and reveals the shortcoming of Butler-Volmer model describing the charge-transfer/ions-diffusion-controlled electrochemical kinetics.