Synthesis of Si anode with a microsized-branched structure from recovered Al scrap for use in Li-Ion batteries

Abstract

Silicon (Si), with a theoretical capacity of 3579 mAh g−1, is an attractive anode material for Lithium-ion batteries. Currently, nano-sized Si, with a diameter less than 150 nm, is the focus of research efforts. However, the difficulty of obtaining a uniform dispersion and increasing the loading ratio of nano-sized Si remains challenging. In this work, a Lithium-ion battery anode was constructed using micro-sized Si from acid-etching of cast Al-Si alloy scraps. The acquired Si has a unique branched structure, with a diameter of 0.5–1 μm in branches and 5–10 μm in length. Compared to the typical, low-loading ratio of much less than 1 mg cm−2 in nano-sized Si, this micro-sized Si anode has a typical loading ratio of 2 mg cm−2. The branched Si with conventional carbon coating demonstrated an initial discharge (lithiation) capacity of 3153 mAh g−1 at the current rate of 1/16C. Moreover, it maintained a discharge capacity of 1133 mAh g−1 at the 100th cycle, under a current rate of 1/4C. The capacity decay was less than 0.2% per cycle from the 20th to the 100th cycle. The rate performance was also promising, with a discharge capacity of 488 mAh g−1 at the current rate of 1C.