Department Of Physics
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Item High-performance symmetric supercapacitor based on activated carbon-decorated nickel diselenide nanospheres(Springer, 2022-11-11T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.The vital challenge is to advance the electronic conductivity of the transition metal diselenide for their supercapacitor application. In this report, nickel diselenide nanospheres and their decoration by activated carbon are reported by a one-step, surfactant-free hydrothermal technique. The activated carbon-decorated NiSe2 nanospheres (NAC) electrode displays high electrochemical performance than pure NiSe2 nanospheres due to more active sites, enhanced conductivity, and reduced diffusion path of electrons and electrolyte ions for maximum energy storage. The NAC electrode depicts a specific capacity of about 119 C g?1 at 0.3 A g?1. The fabricated symmetric supercapacitor using an NAC electrode shows a high specific capacitance of about 282 F g?1 at 10�mV�s?1. The cycle stability of 70% for ten thousand cycles is exhibited for the fabricated symmetric supercapacitor. It manifests high specific energy of 28�W�h�kg?1 and specific power of value 980�W�kg?1 at 1 A g?1. Device applicability with load is tested at laboratory scale by glowing different color LEDs, and a panel of 26 red LEDs illuminated for 56�min effortlessly. A self-explanatory mechanism has also been proposed to make it easier to realize the readers about glowing LEDs, and their panels. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Mesoporous carbon/titanium dioxide composite as an electrode for symmetric/asymmetric solid?state supercapacitors(Elsevier Ltd, 2022-08-27T00:00:00) Arya, Anil; Iqbal, Muzahir; Tanwar, Shweta; Sharma, Annu; Sharma, A.L.; Kumar, VijayThis paper reports the successful synthesis of mesoporous carbon/titanium dioxide (MC/TiO2) composite electrodes via the hydrothermal method for supercapacitor (SC) applications. The morphology and structural properties of MC/TiO2 composites were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectra (FTIR). The electrochemical properties were recorded by cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) with an electrolyte (6 M KOH) in symmetric/asymmetric configuration. The specific capacitance (Cs) evaluated by CV is about 280F/g for composite electrode (95 % capacitance retention after 1000 cycles) and pristine has 150F/g @ 10 mV/s. Enhancement in capacitance is owing to faster charge dynamics within electrode material. The fabricated asymmetric device demonstrates high energy density (30.31 Wh/kg), than the symmetric configuration (?27 Wh/kg). Finally, both symmetric/asymmetric supercapacitors have illuminated a red LED, and strengthens the candidature of composite electrode for energy storage technology. � 2022 Elsevier B.V.Item Structural, microstructural and electrochemical properties of dispersed-type polymer nanocomposite films(Institute of Physics Publishing, 2018) Arya, A.; Sharma, A.L.Free-standing solid polymer nanocomposite (PEO-PVC) + LiPF6-TiO2 films have been prepared through a standard solution-cast technique. The improvement in structural, microstructural and electrochemical properties has been observed on the dispersion of nanofiller in polymer salt complex. X-ray diffraction studies clearly reflect the formation of complex formation, as no corresponding salt peak appeared in the diffractograms. The Fourier transform infrared analysis suggested clear and convincing evidence of polymer-ion, ion-ion and polymer-ion-nanofiller interaction. The highest ionic conductivity of the prepared solid polymer electrolyte (SPE) films is ?5 10-5 S cm-1 for 7 wt.% TiO2. The linear sweep voltammetry provides the electrochemical stability window of the prepared SPE films, about ?3.5 V. The ion transference number has been estimated, t ion = 0.99 through the DC polarization technique. Dielectric spectroscopic studies were performed to understand the ion transport process in polymer electrolytes. All solid polymer electrolytes possess good thermal stability up to 300 ?C. Differential scanning calorimetry analysis confirms the decrease of the melting temperature and signal of glass transition temperature with the addition of nanofiller, which indicates the decrease of crystallinity of the polymer matrix. An absolute correlation between diffusion coefficient (D), ion mobility (?), number density (n), double-layer capacitance (C dl), glass transition temperature, melting temperature (T m), free ion area (%) and conductivity (?) has been observed. A convincing model to study the role of nanofiller in a polymer salt complex has been proposed, which supports the experimental findings. The prepared polymer electrolyte system with significant ionic conductivity, high ionic transference number, and good thermal and voltage stability could be suggested as a potential candidate as electrolyte cum separator for the fabrication of a rechargeable lithium-ion battery system. ? 2018 IOP Publishing Ltd.Item Insights into the use of polyethylene oxide in energy storage/conversion devices: A critical review(Institute of Physics Publishing, 2017) Arya, A.; Sharma, A.L.In this review, the latest updates in poly (ethylene oxide) based electrolytes are summarized. The ultimate goal of researchers globally is towards the development of free-standing solid polymeric separators for energy storage devices. This single free-standing solid polymeric separator may replace the liquid and separator (organic/inorganic) used in existing efficient/smart energy technology. As an example, polyethylene oxide (PEO) consists of an electron donor-rich group which provides coordinating sites to the cation for migration. Owing to this exclusive structure, PEO exhibits some remarkable properties, such as a low glass transition temperature, excellent flexibility, and the ability to make complexation with various metal salts which are unattainable by another polymer host. Hence, the PEO is an emerging candidate that has been most examined or is currently under consideration for application in energy storage devices. This review article first provides a detailed study of the PEO properties, characteristics of the constituents of the polymer electrolyte, and suitable approaches for the modification of polymer electrolytes. Then, the synthesization and characterizations techniques are outlined. The structures, characteristics, and performance during charge-discharge of four types of electrolyte/separators (liquid, plasticized, and dispersed and intercalated electrolyte) are highlighted. The suitable ion transport mechanism proposed by researchers in different renowned groups have been discussed for the better understanding of the ion dynamics in such systems. ? 2017 IOP Publishing Ltd.