Effects of Electrolyte Composition and Voltage Scan Rate on Cyclic Performance of Silicon-Aluminum Anodes for Lithium-Ion Cells

Abstract

Si-Al composite anodes, where micron-sized Si particles are embedded in a ductile Al matrix, were electrochemically cycled in ethylene carbonate (EC)- and propylene carbonate (PC)-based electrolytes vs. Li/Li+. When cycled in PC-based electrolytes, cracks were not formed in Si at a low voltage scan rate of 0.50 mVs-1. However, cracks formed in Si when lithiated in EC-based electrolytes and these cracks were arrested by the surrounding Al-matrix and subsequently closed during de-lithiation. Lithiation at a high scan rate of 5.00 mVs-1 increased the crack formation probability but in PC-based electrolytes, only a few cracks were formed and were closed during de-lithiation. The results suggest that composite Si-Al anodes, which do not pulverize like monolithic Si, could provide durable electrodes for Li-ion batteries—especially if they contain small Si particles (< 10 µm) and cycled in a PC-based electrolyte.