Highly porous Mn3O4 nanosheets with in situ coated carbon enabling fully screen-printed planar supercapacitors with remarkable volumetric performance

Abstract

The most reported planar supercapacitors (PSCs) still suffer from inferior areal/volumetric energy density, and inefficient patterning techniques are unsatisfactory in meeting the requirements of wearable electronic devices. Manganese oxides have attracted significant attention as promising electrode materials for high performing printable PSCs. Nonetheless, their intrinsically inferior electrical conductivity and large volume change severely restrict their overall capacitive properties. Herein, the porous carbon-coated hexagonal Mn₃O₄ (p-Mn₃O₄@C) nanosheets as an electrode are first fabricated, and are found to possess an expanded operating voltage of 0–1.3 V (vs. Ag/AgCl), prominently boosted specific capacitance (386 F g⁻¹ at 1 A g⁻¹), and superior cycle performance (90.4% retention after 10 000 cycles). More importantly, the resultant fully screen-printed PSC operates stably at 1.3 V and exhibits remarkable electrochemical performance with an extraordinary volumetric energy density (14.1 mW h cm⁻³) and power density (2.6 W cm⁻³) as well as outstanding mechanical flexibility and cycling stability, outperforming the most PSCs reported previously. Moreover, the self-powered system based on this printable PSC and commercial solar cell reveals excellent integration performance and good self-powering capabilities. Collectively, the efficient production of printable pseudocapacitive PSCs with remarkable performance opens a new avenue for enormous potential applications in miniature and flexible electronics.