Accelerating Silicon Anode Development

摘要

Silicon is one of the most promising near-term anode materials because of its theoretical specific capacity (4200mAh/g) compared to commercially available graphite anodes (370mAh/g). However, Si electrodes suffer considerable volume expansion of up to 300% during electrochemical lithiation, leading to electrode cracking and pulverization of the Si, causing rapid capacity degradation. Various approaches had been used to mitigate the volume change including using nanostructured Si materials and Si alloys. The interval distance between nano structures and internal spaces in them can act as structural buffer space to accommodate the volume expansion of Si. Although some of the nanostructured Si materials achieved considerably high capacity and cyclability, they are usually prepared by complicate and high cost synthetic process which are difficult to extend to large scale. The volume expansion of Si can also be suppressed by the presence of inactive components, resulting in the maximum energy density at a given volume expansion. Literature has also shown commercially available and low-cost Si alloys can serve as high capacity Li-storage anodic host materials with certain cyclability. If such Si alloy compounds can be made with required chemical stoichiometry and structural architecture though a simple mechanochemical process. Wildcat Discovery Technologies is developing facile synthesis pathway to prepare Si-alloy active/inactive material. Our approach utilized high-throughput combinatorial research to optimize synthesis process, Si-alloy composition and electrode component to improve the cycling performance of the anode material. Electrode design affects the electrochemical performance significantly other than the impact of active material alone. Here we demonstrated the sensitivity and impact of synthesis conditions and electrode design parameters.