Synthesis and characterization of DNA fenced, self-assembled SnO2 nano-assemblies for supercapacitor applications
2016, Nithiyanantham, Udayashankar, Ramadoss, Ananthakumar, Kundu, Subrata
Self-assembled, aggregated, chain-like SnO2 nano-assemblies were synthesized at room temperature by a simple wet chemical route within an hour in the presence of DNA as a scaffold. The average size of the SnO2 particles and the chain diameter were controlled by tuning the DNA to Sn(II) molar ratio and altering the other reaction parameters. A formation and growth mechanism of the SnO2 NPs on DNA is discussed. The SnO2 chain-like assemblies were utilized as potential anode materials in an electrochemical supercapacitor. From the supercapacitor study, it was found that the SnO2 nanomaterials showed different specific capacitance (Cs) values depending on varying chain-like morphologies and the order of Cs values was: chain-like (small size) > chain-like (large size). The highest Cs of 209 F g−1 at a scan rate of 5 mV s−1 was observed for SnO2 nano-assemblies having chain-like structure with a smaller size. The long term cycling stability study of a chain-like SnO2 electrode was found to be stable and retained ca. 71% of the initial specific capacitance, even after 5000 cycles. A supercapacitor study revealed that both morphologies can be used as a potential anode material and the best efficiency was observed for small sized chain-like morphology which is due to their higher BET surface area and specific structural orientation. The proposed route, by virtue of its simplicity and being environmentally benign, might become a future promising candidate for further processing, assembly, and practical application of other oxide based nanostructure materials.
Realization of high performance flexible wire supercapacitors based on 3-dimensional NiCo2O4/Ni fibers
2016, Ramadoss, Ananthakumar, Kang, Kyeong-Nam, Ahn, Hyo-Jin, Kim, Sun-I, Ryu, Seung-Tak, Jang, Ji-Hyun
The rapidly developing electronics industry is producing miniaturized electronic devices with flexible, portable and wearable characteristics, requiring high-performance miniature energy storage devices with flexible and light weight properties. Herein, we have successfully fabricated highly porous, binder free three-dimensional flower-like NiCo2O4/Ni nanostructures on Ni-wire as a fiber electrode for high-performance flexible fiber supercapacitors. Such a unique structure exhibited remarkable electrochemical performance with high capacitance (29.7 F cm−3 at 2.5 mA), excellent rate capability (97.5% retention at 20 mA), and super cycling stability (80% retention, even after 5000 cycles). The remarkable electrochemical performance is attributed to the large active area in the 3D porous architecture and direct contact between the active materials and 3D-Ni current collectors, which facilitate easy ionic/electronic transport. The symmetric fiber supercapacitor showed a gravimetric energy density of 2.18 W h kg−1 (0.21 mW h cm−3) and a power density of 21.6 W kg−1 (2.1 mW cm−3) with good flexibility and cycling performance, signifying potential applications in high-performance flexible energy storage devices. Further, performance in a self-powered system was demonstrated by charging these wire type NiCo2O4/Ni supercapacitors by serially wound DSSCs to drive commercial LEDs. These results suggest that the fabricated device has excellent potential as a power source for flexible, portable and wearable applications as well as self-powered systems.