Scalable one-step production of electrochemically exfoliated graphene decorated with transition metal oxides for high-performance supercapacitors†
Graphene and related materials have been widely studied due to their superior properties in a wide range of applications. However, large-scale production remains a critical challenge to enable commercial acceptance. Here, we present a facile, scalable, one-step electrochemical method for producing hybrid transition metal oxide (V, Fe, Ti, or Mn)/graphene materials (TMO-EGs) as active materials for supercapacitors. Therein, we have designed and developed a continuous flow reactor with a high production rate (>4 g h−1) of TMO-EGs, where the TMO accounts for 36 weight%. TMO-EG flakes demonstrate a moderate lateral size of up to 5 μm and a specific surface area of 64 m2 g−1. Notably, TMO-EGs present a capacitance of up to 188 F g−1 as single electrodes in 4 M LiCl. The most promising material, MnOx-EG, has been used for the large-scale production of thin-film supercapacitor devices (40 × 40 × 0.25 mm) in a commercial pilot line. Using 1 M Na2SO4 as the electrolyte, the as-fabricated devices deliver a capacitance of 52 mF cm−2, with 83% capacitance retention after 6000 charge–discharge cycles, comparable to recent reports of similar devices. The simplicity, scalability, and versatility of our method are highly promising to promote the commercial applications of graphene-based materials and can be further developed for the upscalable production of other 2D materials, such as transition metal dichalcogenides and MXenes.