To understand the kinetics of the reaction products (Li-Si alloys, Li 2O and Li4 SiO4) in SiOx anodes for Li-ion batteries, the irreversible behavior of the batteries is studied while controlling the amount of Li-ion insertion at various current densities. SiOx is charged when the amount of Li inserted into SiOx is varied (0.1, 0.2, 0.5, and 4 mol per 1 mol of SiOx, also called "mole control") and is discharged to 1.5 V at various Crates. The irreversible capacity of SiOx increases at high mole rate, but decreases at high Crates. To observe the formation of the reaction products after mole control at various current densities, impedance and X-ray photoelectron spectroscopy are used. Also, the relative quantity of irreversible products (Li4SiO4) after mole control at various current densities is detected by Fast Fourier transform (FFT). Upon evaluating the dQ/dV curves, it was determined that the elevated rate of the overpotential of the irreversible products (Li2O, Li4SiO4) was higher than that of the reversible products (Li-Si alloys) as the current density increased. The use of the Butler-Volmer equation shows that the activation energy of the reaction products is affected by the current density, which changes the irreversible capacity of SiOx during cycling.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry