Mitigation and In Situ Probing of Volume Expansion in Silicon/Graphene Hybrid Anodes for High‐Capacity, High‐Rate‐Capable Lithium‐Ion Batteries

Abstract

Internal macropores in silicon/graphene/graphene nanoribbon (Si/Gr/GNR) hybrid anodes by facile thermal removal of sacrificial polymer, polyvinyl alcohol (PVA), are incorporated, to mitigate the volume expansion of silicon and to increase the silicon utilization and rate capability of the anode. The resulting Si/Gr/GNR hybrid anodes give a high capacity of 1874 mAh g−1 at 0.1 C, based on total weight of the electrode including binder and carbon, as well as great capacity retention of above 800 mAh g−1 after 350 cycles at 0.3 C. The mitigation of volume expansion by carrying out in situ thickness change measurements of small pouch cells via a dilatometer is further demonstrated, exhibiting the saturation of volume expansion below 40% after 100 cycles due to the incorporation of the macropores. Moreover, Si/Gr/GNR anodes with pores exhibit superior rate capability, yielding 1,250 mAh g−1 at 2 C rate due to the effective network of graphene sheets and GNRs.