Enhanced low-temperature lithium storage performance of multilayer graphene made through an improved ionic liquid-assisted synthesis

• Ionic liquid-assisted synthesis of multilayer graphene with low number of defects.
• High-quality (low defect) multilayer graphene as anode material for lithium-ion batteries.
• High-quality graphene structure offers low first cycle irreversible capacity.
• Multilayer (up to ten) graphene offers enhanced Li+ storage at low temperatures (<0 °C).

The electrochemical properties of graphene are strongly depending on its synthesis. Between the different methods proposed so far, liquid phase exfoliation turns out to be a promising method for the production of graphene. Unfortunately, the low yield of this technique, in term of solid material obtained, still limit its use to small scale applications. In this article we propose a low cost and environmentally friendly method for producing multilayer crystalline graphene with high yield. Such innovative approach, involving an improved ionic liquid assisted, microwave exfoliation of expanded graphite, allows the production of graphene with advanced lithium ion storage performance, for the first time, at low temperatures (<0 °C), as low as −30 °C, with respect to commercially available graphite.