Electrochemical Characterization of Silicon Nanocrystals Embedded in Alloy Matrix As Anode Materials for Lithium-Ion Cells

Silicon has been regarded as one of the most promising anode materials to increase the energy density of lithium-ion batteries by replacing graphite materials due to its high theoretical capacity.1 However, the practical application of silicon materials in lithium-ion batteries is hampered by the large volume changes that occur during repeated cycling, which result in the cracking of the electrode, loss of electrical contact, unstable solid electrolyte interphase (SEI) formation, and eventually rapid capacity fading upon cycling.2,3 The promising approach to overcome the above problems is the utilization of active-inactive alloy systems, where the electrochemical reaction occurs in the active phase and the inactive phases help to improve electronic conductivity and act as a volume buffer. In the present work, we synthesized silicon alloys composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. The matrix phases have a mechanical property to endure the stress generated by the volume expansion of Si during cycling in addition to high electrical conductivity for fast electron transfer to silicon. This strategy resulted in enhanced cycling performance in terms of discharge capacity, capacity retention and rate capability. These superior performances could be attributed to its unique structure with silicon particle embedded by alloy matrix, which could effectively accommodate the large volume change during cycling and provide continuous electronic pathway in the electrode. Detailed characterization of the silicon alloy materials along with their electrochemical performance as anode in lithium-ion cells will be presented. References 1. V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach, Energy Environ. Sci. , 4 , 3243 (2011). 2. B. Key, R. Bhattacharyya, M. Morcrette, V. Seznec, J.-M. Tarascon and C. P. Grey, J. Amer. Chem. Soc. , 131 , 9239 (2009). 3. M. T. McDowell, S. W. Lee, W. D. Nix and Y. Cui, Adv. Mater. , 25 , 4966 (2013) .