Regulating cations and solvents of the electrolyte for ultra-efficient electrochemical production of high-quality graphene

Electrochemical exfoliation of graphite has been regarded as a potential approach to produce graphene on a large scale. Despite recent progress in the production of graphene with few defects by cathodic exfoliation, current methods suffer from uncontrolled thicknesses and limited yield. Here we devise a novel cathodic exfoliation method using diverse tetraalkylammonium cations in various non-aqueous solvents toward efficient preparation of high-quality graphene. Sandwich-structured graphite electrode enables sufficient ion intercalation and uniform exfoliation into few-layer graphene (>80%, 1–3 layers), along with remarkable yield (91.5%) and ultralow defect density (I_D/I_G = 0.05). The interplay of electrolyte cation and solvent on its intercalation efficiency and electrochemical stability was also studied, which are in direct correlation with the exfoliation ability. Further mechanism investigation demonstrates that tetrabutylammonium cations in propylene carbonate can intercalate into graphite efficiently under reducing condition. Adjacent layers were then taken apart rapidly due to gas formation reactions, resulting in non-destructive exfoliation. The preparation process can be easily scaled up and yield a high production rate (exceeding 50 g h⁻¹), demonstrating its potential to facilitate the mass production of high-quality graphene for extensive applications.