The industrial scale production and application of liquid conductive nanomaterials with well-defined conductive properties, printing adaptability and mechanical properties are crucial for the flexible electronic devices. Although graphene can be used as an attractive liquid nanoink platform for electronic devices, it is still a major challenge to prepare graphene conductive inks with high concentration, conductivity and stability with graphene powders as raw materials and improve the post-treatment process for printed patterns. Here, a novel graphene-based screen printing conductive ink employing liquid-exfoliated graphene powders produced by jet cavitation and carbon black jointly as conductive filler is presented. The inks with graphene powders containing thicker smaller-area flakes and carbon black fraction of 15% in the total conductive fillers exhibit printability down to lines of 90 lm in width and printed pattern electrical conductivity of 2.15 x 10(4) S/m at 7 mu m thickness along with outstanding mechanical properties. Also, special post-treatment, i.e. heating-compression rolling-heating, makes the conductive ink formulation compatible with a wide range of substrates and suitable for Roll-to-Roll applications. Overall, this paper provides a new solution to high-efficiency, low-cost, large-scale production of printed flexible electronics. (C) 2020 Published by Elsevier Inc.