Department Of Physics
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Item All-redox hybrid supercapacitors based on carbon modified stacked zinc cobaltite nanosheets(Royal Society of Chemistry, 2023-09-12T00:00:00) Kour, Simran; Kour, Pawanpreet; Sharma, A.L.The role of energy in the present century has increased with the fast advancement of the global economy. In this regard, hybrid supercapacitors (HSCs) as energy storage systems have become an extensive research focus worldwide. This study reports the synthesis of carbon-loaded ZnCo2O4 stacked nanosheets via an in situ hydrothermal process followed by annealing. The electrochemical response was tested in a 2-electrode system. The optimized composite exhibited a capacitance of ?527.6 F g?1 at 5 mV s?1. The symmetric SC (SSC) possessed an energy density (Ed) of ?17.3 W h kg?1 corresponding to a power density (Pd) of 2.25 kW kg?1. Two asymmetric all-redox HSCs have also been fabricated using an optimized composite material as the positive electrode. The previously synthesized MnCo2O4/AC (HSC1) and MnO2/AC (HSC2) were taken as negative electrodes. HSC1 exhibited an Ed of ?24.4 W h kg?1 corresponding to a Pd of ?0.8 kW kg?1. On the other hand, HSC2 exhibited the highest Ed of ?30.8 W h kg?1 at 2.4 kW kg?1. The real-time application of the composite is tested with the fabricated HSCs. HSC1 exhibited a capacitive retention of ?72.2% after 10 000 cycles. On the other hand, HSC2 exhibited a capacitive retention of ?73.4% after 10 000 cycles. The SSC, HSC1, and HSC2 illuminated a 39 red LED panel for ?3 min, 7 min, and 13 min, respectively. The results suggested the promising performance of all-redox HSCs. The overall results present a sustainable approach for creating hierarchical energy materials for the construction of future energy-storage systems. � 2023 The Royal Society of Chemistry.Item Self-assembled carbon wrapped manganese cobaltite nano-composite with promising electrochemical performance for symmetric and asymmetric supercapacitor device(Elsevier Ltd, 2023-05-27T00:00:00) Kour, Simran; Kour, Pawanpreet; Sharma, A.L.The growing energy requirements of modern society have led to an intensive search for advanced supercapacitor (SC) electrode materials. Binary transition metal oxides with excellent supercapacitive performance are among the most promising materials. However, the phase transformation of these metal oxides during repeated charging/discharging is a major concern, which depletes their cyclic performance. Coating metal oxides with carbon can provide structural stability to the metal oxide, thereby increasing their cyclic life. In addition, the highly conductive carbon enhances the capacitance of metal oxides by allowing the effective transfer of charges from MnCo2O4 to the current collector. In this study, self-assembled carbon-wrapped MnCo2O4 composite has been prepared through a two-step process involving hydrothermal and solution-mixing processes. The structural/electrochemical performances of the composites have been investigated. The optimized composite offered a maximum capacitance of 626.8 Fg?1 withholding 98 % of capacitance for 6000 cycles. Furthermore, the electrochemical performance of the composite has also been tested in an all-redox symmetric SC (SSC) as well asymmetric (ASC) configuration. In the symmetric cell, 30.2 Whkg?1 of energy is reported for 1.6 kWkg?1 of power. The asymmetric cell with the optimized composite as a cathode and MnO2/Activated carbon as an anode was fabricated. The ASC displayed 45.5 Whkg?1 of energy corresponding to 10 kWkg?1. Three SSCs/ASCs in series illuminated a panel of 39 red-LEDs for 9 and 15 min, respectively. The results suggest the promising performance of such composites for hybrid supercapacitors. Thus, the fabrication of all-redox-type SSCs/ASCs can be a futuristic approach for hybrid storage systems. � 2023 Elsevier LtdItem Aging impact on morphological and electrochemical performance of MoSe2 composite for supercapacitor application(Elsevier Ltd, 2023-02-27T00:00:00) Tanwar, Shweta; Sharma, A.L.The report is associated with the investigation of the impact of selenium powder aging in hydrazine hydrate acting as a reducing agent on the electrochemical performance of the molybdenum diselenide/activated carbon (MoSe2@AC) composite-based electrodes, and its supercapacitor application. The MoSe2@AC composite is formulated via the simple hydrothermal method. The composite formation is validated via structural, chemical bond, and morphology investigation. Among all synthesized samples, six days aged sample coded M6AC appears to exhibit the best electrochemical performance. The specific capacitance estimated for M6AC material-based fabricated symmetric cell is around 394 F g?1 at the 1 A g?1 using KOH (6 M) electrolyte. The energy and power density delivered by the same cell at 1 A g?1 is about 55 W h kg?1 and 845 W kg?1 correspondingly. Furthermore, we have tested the real-world usability of the M6AC symmetric cell by illuminating different voltage cum colors light emitting diodes (LEDs). The 26 red LEDs in the parallel connection illuminate for approximately 32 min with the aid of our fabricated symmetric cell as the power source. For easy understanding of the readers, we also report the self-proposed charge storage mechanism linked with the glowing LEDs using our obtained experimental results. Thereby, the observed outcomes associated with the M6AC material indicate that it has immense potential for scaling its performance at the industrial cum commercial level to resolve the energy crisis problem of the society. � 2023Item Development of novel cathode materials based on MWCNT for energy storage/conversion devices(Springer Science and Business Media, LLC, 2017) Agnihotri, Shruti; Rattan, Sangeeta; Sharma, A. L.In Chap. 1, already available technology for energy storage solutions like capacitors, lead acid batteries, compressed air energy storage, flywheels has been discussed in order to compare their energy and power densities. Emphasis has been laid on Rechargeable Lithium ion Battery (Li-ion). Various materials which are already explored and used as cathode of battery has also been discussed with their merits and demerits. Further introduction of prepared orthosilicate material with used conductive additive Multiwalled carbon nano tube (MWCNT) has also given. In Chap. 2, methodology used to prepare respective Li2MnFeSiO4 material and its composite with MWCNT has been discussed in detail. Further, in order to validate its electrochemical application, different steps of cell assembly of Lithium half cell fabrication has also been discussed. Chapter 3 comprises of results obtained using standard Field emission scanning electron microscope (FESEM). Effect of used MWCNT on its morphology has been discussed in this chapter. A.C Impedance spectroscopy has been used to study variation in conductivity with respect to bared material. Possible reasons for increased conductivity with morphology has also been discussed in discussion. Chapter 4 includes conclusions drawn from mentioned results. This chapter summarizes measured conductivity values with different concentrations of MWCNT. Improved conductivity with respect to bared orthosilicate material has been pointed in this chapter. ? Springer International Publishing Switzerland 2017.