Parthiban Pazhamalai

Titanium carbide sheet based high performance wire type solid state supercapacitors

Two dimensional sheets based on transition metal carbides have attracted much attention in electrochemical energy storage sectors. In this work, we demonstrated the fabrication and performance of titanium carbide based wire type supercapacitors (WSCs) towards next generation energy storage devices. The layered titanium carbide sheets were prepared via selective extraction of Al from the precursor Ti2AlC using hydrofluoric acid and are extensively characterized using X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform-infrared spectroscopy, and laser Raman spectral analyses, respectively. The X-ray photoelectron spectroscopy studies confirmed the presence of oxygen and fluorinated functional groups attached on the surface of titanium carbide. The electrochemical studies of the fabricated titanium carbide WSC devices showed ideal capacitive properties with a specific length capacitance of 3.09 mF cm−1 (gravimetric capacitance of about 4.64 F g−1), and specific energy density of about 210 nW h cm−1 (in length) or 315 mW h kg−1 (in gravimetric) with excellent cycling stability. Further, a detailed examination of the capacitive and charge-transfer behavior of titanium carbide WSCs has been investigated via electrochemical impedance analysis using Nyquist and Bode plots. Additionally, we have also demonstrated the practical application of the titanium carbide WSCs, highlighting the path for their huge potential in energy storage and management sectors.

Two-dimensional siloxene nanosheets: novel high-performance supercapacitor electrode materials

Silicon-based materials have attracted considerable interest for the development of energy storage devices because of their ease of integration with the existing silicon semiconductor technology. Herein, we have prepared siloxene sheets—a two-dimensional (2D) silicon material—and investigated their energy storage properties via fabrication of a symmetric supercapacitor (SSC) device containing 0.5 M tetraethylammonium tetrafluoroborate as the electrolyte. The formation of 2D siloxene sheets functionalized with oxygen, hydrogen, and hydroxyl groups was confirmed through X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and laser Raman mapping analyses. Cyclic voltammetric studies of the siloxene SSC device revealed the presence of pseudocapacitance in the siloxene sheets that arose from an intercalation/deintercalation phenomenon. The galvanostatic charge–discharge profiles of the device displayed sloped symmetric triangular curves with a maximum specific capacitance of 2.18 mF cm−2, high energy density of 9.82 mJ cm−2, good rate capability, and excellent cycling stability of 98% capacitance retention after 10 000 cycles. The siloxene SSC device delivered a maximum power density of 272.5 mW cm−2, which is higher than those of other silicon- and carbon-based SSCs, highlighting their potential for application in energy storage.

Blue TiO2 nanosheets as a high-performance electrode material for supercapacitors

We are reporting the use of blue titanium oxide (b-TiO2) nanostructures as advanced electrode material for high performance supercapacitor for the first time. A one-pot hydrothermal route was employed for the oxidation of layered titanium diboride (TiB2) into b-TiO2 nanosheets. The b-TiO2 nanosheets are prepared via hydrothermal oxidation of TiB2. Physico-chemical characterizations such as X-ray diffraction, UV-visible, photoluminescence spectroscopy, electron spin resonance spectroscopy, laser Raman spectrum, X-ray photoelectron spectroscopy, and morphological studies revealed the formation of sheet-like b-TiO2 nanostructures. The energy storage properties of the b-TiO2 electrode were examined using aqueous and organic electrolytes. The cyclic voltammetry and charge-discharge analysis of b-TiO2 electrode using 1 M Na2SO4 revealed their pseudocapacitive nature with a high specific capacitance (∼19 mF cm-2). The b-TiO2 based symmetric supercapacitor (SSC) device using organic liquid (1 M TEABF4) works over a wide operating potential window (3 V) and delivered a high specific capacitance (6.67 F g-1 or 3.58 mF cm-2), possess high energy density and power density with excellent cyclic stability over 10,000 cycles. Collectively, these studies demonstrated the usefulness of b-TiO2 as a novel electrode material for high performance supercapacitor.