Lithium diffusion through the TiN coating layer and formation of Li-Si alloy over Si@TiN anode

In this study, the diffusion of lithium in the TiN layer and the formation of Li-Si alloy over [email protected] anode are experimentally evaluated with the help of in-situ X-ray diffraction. The results reveal that lithium diffuses into TiN layer and reacts with the Si core to produce Li-Si alloy once the temperature is higher than 200 °C. Raising temperature contributes to more Li-Si alloy, and the alloying reaction is controlled by diffusion. Increasing reaction time leads to the enlargement of Li-Si alloy crystal size and the mathematical fitting between Si conversion and reaction time suggests that the formation of Li-Si alloy corresponds with the shrinking core model in [email protected] system. Empirical equation is also established to describe the diffusion of lithium in TiN layer, where the potential energy barrier is 19.4 kJ/mol and pre-exponent is 2.2×10-18 m2/s. This work is beneficial to know deep insight into the lithium diffusion through TiN layer and the formation of Li-Si alloy over [email protected] anode.