Yuanlong Shao, Jui-Han Fu, Zhen Cao, Kepeng Song, Ruofan Sun, Yi Wan, Atif Shamim, Luigi Cavallo, Yu Han, Richard B. Kaner, Vincent C. Tung
ACS Nano, (2020)
Metallic molybdenum disulfide (MoS2), e.g., 1T phase, is touted as a highly promising material for energy storage that already displays a great capacitive performance. However, due to its tendency to aggregate and restack, it remains a formidable challenge to assemble a high-performance electrode without scrambling the intrinsic structure. Here, we report an electrohydrodynamic-assisted fabrication of 3D crumpled MoS2 (c-MoS2) and its formation of an additive-free stable ink for scalable inkjet printing. The 3D c-MoS2 powders exhibited a high concentration of metallic 1T phase and an ultrathin structure. The aggregation-resistant properties of the 3D crumpled particles endow the electrodes with open space for electrolyte ion transport. Importantly, we experimentally discovered and theoretically validated that 3D 1T c-MoS2 enables an extended electrochemical stable working potential range and enhanced capacitive performance in a bivalent magnesium-ion aqueous electrolyte. With reduced graphene oxide (rGO) as the positive electrode material, we inkjet-printed 96 rigid asymmetric micro-supercapacitors (AMSCs) on a 4-in. Si/SiO2 wafer and 100 flexible AMSCs on photo paper. These AMSCs exhibited a wide stable working voltage of 1.75 V and excellent capacitance retention of 96% over 20 000 cycles for a single device. Our work highlights the promise of 3D layered materials as well-dispersed functional materials for large-scale printed flexible energy storage devices.