▎ 摘　　要

Stable aqueous carbon inks, with graphene sheets (GSs) and carbon black (CB) as conductive fillers, are prepared by a simple one-pot ball-milling method. The as-prepared composite ink with 10 wt% GSs shows optimized rheological properties (viscosity and thixotropy) for screen printing. The as-printed coatings based on the above ink are uniform and dense on a polyimide substrate, and exhibit a sandwich-type conductive three dimensional network at the microscale. The resistivity of the typical composite coating is as low as 0.23 +/- 0.01 omega cm (92 +/- 4 omega sq(-1), 25 mu m), which is 30% as that of a pure CB coating (0.77 +/- 0.01 omega cm). It is noteworthy that the resistivity decreases to 0.18 +/- 0.01 omega cm (72 +/- 4 omega sq(-1), 25 mu m) after a further rolling compression. The coating exhibits good mechanical flexibility, and the resistance slightly increases by 12% after 3000 bending cycles. With the CB/GSs composite coatings as a flexible conductor, fascinating luminescent bookmarks and membrane switches were fabricated, demonstrating the tremendous potential of these coatings in the commercial production of flexible electronics and devices.