The next generation of lithium-ion batteries (LIBs) for the application in miniaturized electronic devices and traction batteries need further development of new active materials with higher specific capacities to increase the resulting energy and power of the battery cells. In particular, new anode materials with high specific capacities and improved cycling performance are of great interest.[1]

Since silicon provides a very high gravimetric and volumetric capacity, a low operation potential and low costs, it is widely regarded as the most promising anode material in LIBs for the future.[1] However, major issues arise from its poor capacity retention due to mechanical degradation caused by the large volume expansion during lithium insertion/extraction. In recent years, several attempts have been undertaken to overcome this problem.[2] Compared to bulk silicon anodes, which contain at least 10 wt.% of inactive binders and conductive additives, silicon thin film anodes contain no inactive materials, giving an increased specific capacity.[3]

In this work, silicon-carbon thin films have been prepared by magnetron sputtering. The silicon-carbon thin films have been prepared by alternatively sputtering layers of silicon and carbon (layered structure of silicon and carbon) or by co-sputtering silicon and carbon (mixed silicon-carbon layers). The characterization of the electrodes was performed by focused ion beam-scanning electron microscopy (FIB-SEM), Raman spectroscopy and electrochemical impedance spectroscopy. Furthermore, the influence of the carbon content and layered/non-layered silicon-carbon structure was thoroughly investigated in cycling experiments compared to the bare thin film silicon electrodes.

Literature:

[1] R. Wagner, N. Preschitschek, S. Passerini, J. Leker, M. Winter, J Appl Electrochem. 43 (2013) 481-496.

[2] M.N. Obrovac, L.J. Krause, J Electrochem Soc. 154 (2007) A103-A108.

[3] U. Kasavajjula, C. Wang, A.J. Appleby, J Power Sources, 163 (2007) 1003-1039.