Metallization of Silicon Particles for Improved Li-Ion Battery Anodes

Silicon is a material that has gained particular interest for the application as anode active material in lithium ion batteries, thanks to its unique reversible lithium insertion capability, which can lead to very high values of specific capacity. However, the main drawback that prevented the spreading of this material in industrial application is its structural instability upon lithium insertion cycling, and different solution have been proposed to address this issue ^1,2. The very high volume variation that occurs to silicon during cycling leads to difficulty to establish a continuative electrical contact between Si particles and the rest of the electrode. The approach developed in this work is to apply a nanostructured metallic coating to the Si particles, helping to overcome the continuous stresses during cycling and maintaining electrical contact.

In this work, two different metallization techniques have been tested. The presence and composition of the coating on the surface of the particles is confirmed by SEM/EDX and XRD analysis. Anodes containing at least 20%wt Si have been manufactured to perform the electrochemical characterization and to assess the cycling behavior. Coated particles show enhanced structural stability upon cycling, leading to improved cycling efficiency and cycle life. Specific capacity values around 1000 mAh/g are achieved with a 40% increase with respect to pristine Si.

References:

1. C. K. Chan et al., Nature nanotechnology, 3, 31–35 (2008).

2. B. A. Boukamp, Journal of The Electrochemical Society, 128, 725 (1981).