Improving Li-ion battery anodes by surface modification

Silicon (Si) is a promising anode material for Li-ion batteries due to its high theoretical capacity (10 times higher than commonly used graphite) and abundant presence in the earth’s crust. However, the formation of an unstable solid-electrolyte interphase (SEI) and significant volume expansion during lithiation result in structural degradation, leading to a decrease in the cycle life for Si-based anodes.

Our colleagues from Department of physics and technology at nanoscale together with researchers from Centre for advanced materials application SAS we have recently reported on the electrochemical performance of the silicon/graphite (Si/Gr) electrodes coated with ZnO layers prepared by atomic layer deposition (ALD). In this study, ZnO layers were deposited using 5−40 ALD cycles (thickness of 1-8 nm) on Si/Gr electrodes of ∼20 μm thickness. Electrochemical measurements such as charging/discharging at different rates and electrochemical impedance showed that the ZnO-coated samples showed a better electrochemical rate performance than the uncoated pristine Si/Gr sample particularly at high charging/discharging rates. As confirmed by scanning electron microscopy and X-ray photoelectron spectroscopy (XPS), the ultrathin ZnO layers passivate the underlying Si/Gr electrodes, help in the formation of a stable SEI layer, and facilitate lithium-ion transport through the SEI layer. As a consequence, the rate capability became significantly improved for the ZnO-coated Si/Gr anodes.
Our study demonstrated that ALD represents a promising technique of Li-ion battery anodes surface modification resulting in improvement of their performance.

Sahoo, P.P., Güneren, A., Hudec, B., Mikolášek, M. Nada, A., Precnerová, M., Mičušík, M., Lenčéš, Z. Nadáždy, P., Fröhlich, K., Stabilization of the Solid-Electrolyte-Interphase Layer and Improvement of the Performance of Silicon−Graphite Anodes by Nanometer-Thick Atomic-Layer-Deposited ZnO Films, https://doi.org/10.1021/acsanm.3c05066.

Prepared by: B. Hudec