Good cycling performance of high-density arrays of Si microwires as anodes for Li ion batteries

Optimized Si wire anodes have been prepared by macropore etching in p-Si and subsequent chemical/galvanic processing. The anodes have been optimized with respect to capacity, cycling performance and processing costs by fine-tuning the wire geometry. The optimized anodes have wires with ≈1 μm in diameter and length of 70 μm; they are as densely spaced as possible regarding volume expansion and electrolyte penetration requirements. A stable capacity of 3150 mAh/g for 100 cycles has been reached during cycling to 75% of the maximum capacity. The operational range of the anodes is 0.11–0.7 V. Optimal charging conditions were established by cyclic voltammetry measurements and battery cycling tests.