Department Of Physics
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Item Fabrication of activated carbon coated MSe2 (M=Mo, Co, and Ni) nanocomposite electrode for high-performance aqueous asymmetric supercapacitor(Elsevier B.V., 2023-03-09T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.Transition metal diselenides are trendy electrode materials for supercapacitors. The main reason behind it is their high specific capacitance. But, they suffer from poor electronic conductivity and agglomeration issues which hinder their practical use. Herein, we present the preparation of nanocomposites including transition metal diselenide MSe2 (M=Mo, Co, and Ni) with activated carbon using the facial hydrothermal route. Inspiring from the high electrochemical results of a hybrid nanocomposites symmetric cell, an aqueous asymmetric ultracapacitor cell (AUC) comprised of different shaped carbon-coated MSe2 (positive electrode) as well as activated carbon (AC) (negative electrode) has been fabricated. The NAC//6KOH//AC asymmetric cell displays the best outcomes among all fabricated devices. The specific capacitance observed is about 3740 F g?1 at 10 mV s?1. It delivers a high energy density of 69 Wh kg?1 along with a power density of 687 W kg?1 at 1 A g?1. The electrochemical results motivate us to explore the practical usability of the prepared NAC//6KOH//AC device via illuminating 26 red LED panels which glow for 26 min. The findings in this report indicate that MSe2-based nanocomposite has the scope and is a potential material in the energy storage field. � 2023 Elsevier B.V.Item Structural, Electrical and Electrochemical Properties of Fe Doped Orthosilicate Cathode Materials(Springer Nature, 2021-12-02T00:00:00) Singh, Nirbhay; Kanwar, Komal; Tanwar, Shweta; Sharma, A.L.; Yadav, B.C.We report the paper related to the effect of Fe doping on the Li2FexMn1?xSiO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) cathode materials synthesized by Sol-Gel technique. X-Ray Diffraction evidences the monoclinic structure with space group Pn(7) and crystal size decreases from 43 to 35�nm on doping Fe in Li2MnSiO4. Field emission scanning electron microscopy (FESEM) confirms that particle size reduces from 60 to 21�nm with increase of Fe concentration. The impedance analysis shows that highest electrical conductivity was 4.5 � 10�5 Scm?1 for Li2Fe0.4Mn0.6SiO4 cathode material. The initial specific capacity was 152 mAhg?1 at the rate of 0.1 C and 131 mAhg?1 after the 50th cycle with 86% capacity retention. The doping of Fe enhanced the conductivity by reducing its charge transfer resistance and increasing Li-ion diffusion coefficient than the pure Li2MnSiO4 cathode material. � 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.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.