Porous amorphous silicon film anodes for high-capacity and stable all-solid-state lithium batteries

Abstract

Owing to its high theoretical capacity of ~4200 mAh g−1 and low electrode potential (<0.35 V vs. Li+/Li), utilising silicon as anode material can boost the energy density of rechargeable lithium batteries. Nevertheless, the volume change (~300%) in silicon during lithiation/delithiation makes stable cycling challenging. Since some of the capacity fading mechanisms do not function in solid electrolytes, silicon anodes exhibit better cycling performance in solid electrolytes than liquids. Nonetheless, capacity can fade rapidly because of the difficulties in maintaining mechanical integrity in thick/bulky electrodes, especially when high active material loading is employed to deliver practically useful areal capacity. By contrast, silicon nanostructures can relieve deformation-induced stress and enhance cycling performance. Here we report enhanced cycling performances achieved using nanostructured silicon films and inorganic solid electrolyte and show that amorphous porous silicon films maintain high capacity upon cycling (2962 mAh g−1 and 2.19 mAh cm−2 after 100 cycles).