Large-scale low-cost preparation methods for high quality graphene are critical for advancing graphene-based applications in energy storage, and beyond. Here, we present a sulfur-assisted method that converts benzene rings of tetraphenyltin into high purity crystalline graphene. Specifically, three dimensional few layer graphene microspheres (FLGMs) were prepared which proved ideal for energy storage applications. For a potassium ion battery, the FLGM-based anodes exhibited a low discharge platform (average discharge platform about 0.1 V), a high initial capacity of 285 mA h g−1 at 50 mA g−1, and a high rate performance (252 mA h g−1 at 100 mA g−1 and 95 mA h g−1 at 1000 mA g−1). Additionally, the FLGM-based anodes exhibited excellent cycling stability with no capacity loss after 1000 cycles at 200 mA g−1. A process of this nature which does not require substrates, and is scalable for continuous or semi-continuous production of graphene, paves the way for graphene-based energy storage devices.
