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, MnO_x-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.