Faculty Publications
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Item Enhanced Power Density of Graphene Oxide–Phosphotetradecavanadate Nanohybrid for Supercapacitor Electrode(Springer, 2021) Maity, S.; Anandan Vannathan, A.A.; Kumar, K.; Das, P.P.; Mal, S.S.Successful exploration of supercapacitor (SC) material to integrate with high energy and high power density storage device still remains a daunting challenge. Conducting carbon nanostructures have been primarily used for this purpose; however, most of their surface area remains unutilized throughout the storage process. Herein, a new type of hybrid material has been reported by effectively using active sides of carbon nanostructures. Insertion of faradaic-type polyoxometalates (POMs), namely phosphotetradecavanadate (Na7[H2PV14O42], hereafter described as PV14), into the graphene oxide (GO) matrix creates a novel hybrid material for SC applications. Owing to the formation of nanohybrid, it can store charges both electrostatically and electrochemically. PV14/GO composite’s electrochemical behavior in different electrolyte (acidic/neutral) solutions shows different types of characteristics. The PV14/GO composite as a working electrode exhibits a high galvanostatic capacitance of 139 F/g while maintaining at a power density of 97.94 W/kg in 0.25 M H2SO4 electrolyte. The specific energy density was also found out to be around 56.58 Wh/kg at a 5 mV/s scan rate for the same electrolyte. Furthermore, in 1 M Na2SO4 solution, PV14/GO composite demonstrates a specific capacitance of 85.4 F/g at a scan rate of 5 mV/s. The equivalent series resistance for the device was found to be approximately 0.51 ? with a circuit resistance of 3.881 ?, using electrochemical impedance spectroscopy. The cell capacitance, employing the Nyquist plot, was calculated to be around 2.78 mF. © 2021, ASM International.Item Activated carbon- supported Vanado-nickelate (IV) based hybrid materials for energy application(Elsevier Ltd, 2021) Maity, S.; BM, N.; Kella, T.; Shee, D.; Das, P.P.; Mal, S.S.The rapid development of supercapacitor (SC) technology leads to increased demand for nanofabrication of novel and effective electroactive hybrid materials for next-generation energy storage devices. Herein, nickel tetradecavanadate, K2H5[NiV14O40](NiV14), is doped into porous activated carbon (AC), for the first time, in different wt.% in order to investigate the homogeneous loading of the inorganic metal-oxide component on the AC matrix. The resulting complex, AC-NiV14, is found to have possessed an enhanced electrochemical characteristic (for both symmetric and asymmetric SC cell), which operates at a significantly higher potential of 1.2 V. The combination of the double-layer capacitance (EDLC) and the redox-active polyoxometalate cluster leads to an intrinsic increase in specific capacitance (capacity) (from 45.3 Fg?1 (54.4 Cg?1) for AC to 316 Fg?1 (379.2 Cg?1) for 15 wt.% AC-NiV14 at a current density of 1 Ag?1). It was also observed that there is an increase of 20% in the operating voltage compared to conventional AC supercapacitors with acidic aqueous electrolytes. Firstly, symmetric supercapacitor's electrochemical performances of various wt.% of NiV14 composition were studied in acidic aqueous electrolyte (0.5 M H2SO4) solution. We observed that the 15 wt.% of AC-NiV14 hybrid electrode showed remarkable specific energy value (~63.2 Wh kg?1) compared with pristine AC and NiV14 electrodes, separately. Besides, the asymmetric layout (AC//AC-NiV14) increased the potential window up to 1.5 V and enhanced the specific energy and power values (90.1 Whkg?1 and 2400 Wkg?1, respectively), with 98% coulombic efficiency. Meanwhile, the AC-NiV14//NiV14 asymmetric cell possesses a specific capacitance (capacity) of 375 Fg?1 (450 Cg?1) with a maximum power of 3140 Wkg?1 at the high current density of 2 Ag?1. © 2021 Elsevier LtdItem Vanadomanganate as a synergistic component in high-performance symmetric supercapacitor(Elsevier Ltd, 2022) Maity, S.; Anandan Vannathan, A.A.; Chandewar, P.R.; Shee, D.; Das, P.P.; Mal, S.S.Supercapacitor devices fabricated from capacitive and battery-type hybrid electrodes have been projected as a promising energy storage system because of their ability to produce high specific power and energy simultaneously. In this work, we have demonstrated a facile method of impregnation of faradaic type manganese (III) polyoxovanadate, [MnV14O40]−6 on the high surface area substrate of activated carbon (AC) as well as graphene oxide (GO). Materials and electrochemical characterizations data confirm the successful incorporation of capacitive and faradaic type manganese (III) polyoxovanadate into the nanohybrid electrode material. Furthermore, the synergic effect between the carbonaceous nanostructures (AC/GO) and redox-active oxometalate (MnV14) provides a better pathway for ion transport to the interface resulting in enhancement of the conductivity, diffusion ability of the nanohybrid. Moreover, the battery-type MnV14 clusters disperse in the micro/mesopores of AC, whereas the oxygen-containing functional groups in GO act as active sites for anchoring of MnV14 clusters. Thus, the surface modification with MnV14 clusters enhances the specific capacitance of nanohybrid with remarkable electrical and mechanical stability. The AC/MnV14 nanohybrid exhibits an enhanced specific capacitance of 547 F g−1 with specific energy and power of 76 Wh kg−1 and 1600 W kg−1, respectively, at 0.8 A g−1 current density. Additionally, GO/MnV14 shows a specific capacitance of 330 F g−1 with improved specific energy and power of 30 Wh kg−1 and 1276 W kg−1, respectively, at the same current density. Moreover, both the nanohybrids possess excellent cycle stability by retaining 92% (AC/MnV14) and 90.6% (GO/MnV14) of initial capacitance even after 5000 sweeping cycles. © 2021 Elsevier B.V.Item Polyoxovanadate-Activated Carbon-Based Hybrid Materials for High-Performance Electrochemical Capacitors(Institute of Physics, 2022) Anandan Vannathan, A.; Chandewar, P.R.; Shee, D.; Mal, S.S.Two different polyoxovanadates derivatives, K5MnIVV11O32.10 H2O (MnV11) and K7MnIVV13O38.18 H2O (MnV13), have been studied to evaluate their electrochemical performance. These polyoxovanadates were deposited on activated carbon (AC) to prepare AC-MnV11 and AC-MnV13 composites. The electrochemical performance of the AC-MnV11 electrode exhibits the remarkable specific capacitance of 479.73 F g-1 at a current density of 0.6 A g-1, along with incredible specific power and energy of 960 W kg-1. Likewise, the AC-MnV13 exhibits a specific capacitance of 357.33 F g-1 at the current density of 0.6 A g-1 with a specific energy of 71.46 Wh kg-1. Interestingly, the AC-MnV11 could light up the red and yellow color LED bulbs for a duration of 80 and 60 s, respectively, indicating a considerable specific power of the material. The AC-MnV13 electrode shows significantly less lighting up during the 65 and 30 s period with red and yellow LED bulbs. © 2022 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.Item Phosphomolybdic acid embedded into biomass-derived biochar carbon electrode for supercapacitor applications(Elsevier B.V., 2023) J.e, M.; Chandewar, P.R.; Shee, D.; Mal, S.S.In high-performance, clean, safe, and cost-effective ways, supercapacitors are among the most promising ways to store and release nonfossil energy. In recent years, renewable biomass-derived activated carbon has been explored as a potential option for electrode material. It restricts their specific capacitance despite being environment-friendly and possessing intrinsic mechanical strength. In order to overcome this limitation and preserve all other properties, we are infusing polyoxometalate into the activated carbon; this increases specific capacitance with its fast reversible redox behaviour and preserves the carbon's characteristics. Beside suffusing phosphomolybdic acid (PMA) into biomass waste material, such as orange peel-derived activated carbon (OPAC), a new hybrid material (OPAC-PMA) was developed. The nanohybrid design was revealed by structural and morphological research, which showed high interfacial contact, allowing polyanions to redox rapidly. The novel hybrid electrode material (OPAC-PMA) has a capacitance value of 66% higher than the bare OPAC electrode. A further study showed that OPAC-PMA composite showed 88.23% cycle stability in 0.5 M H2SO4 electrolyte at 6 A g−1 for 4000 cycles. © 2023 Elsevier B.V.Item High-performance electrochemical supercapacitors based on polyoxometalate integrated into polyaniline and activated carbon nanohybrid(Springer Science and Business Media Deutschland GmbH, 2023) Anandan Vannathan, A.A.; Kella, T.; Shee, D.; Mal, S.S.Polyaniline (PANI) and carbonaceous materials and metallic compounds have played a significant role in energy storage and conversion devices. PANI has demonstrated tremendous potential in the supercapacitor industry due to its high specific capacitance, high flexibility, and economical price. The CPs damage the hierarchical structure during the charging and discharging process and start swelling. Thus, incorporating polyoxometalates (POMs) into the conducting polymer matrix increases the stability of the electrode material. Here, we have demonstrated a comparative study of two newly synthesized composite materials consisting of K5H2[PV4W8O40] ·11H2O, (PV4W8) POM incorporated into two different supports, such as pseudocapacitive polyaniline (PANI) and EDLC activated carbon (AC) matrix. It was observed that the PANI-PV4W8 composite exhibited excellent capacitance nature at 0.5 M H2SO4 electrolyte solution than AC-PV4W8. The PANI-PV4W8 composite demonstrated the specific capacitance of 584 F g−1 at 0.8 A g−1. The composite also exhibited energy and power density of 81Wh kg−1 and 1598 W kg−1, respectively. Besides, the composite shows 93.13% capacity retention after 4500 cycles by cyclic voltammetry measurement at a 500 mV s−1 scan rate. Furthermore, the AC-PV4W8 showed a specific capacitance of 62 F g−1 at the current density of 0.6 A g−1. Interestingly, The PANI-PV4W8 composite could glow up the red and yellow LED bulb for more than a minute, suggesting a promising electrode material for practical supercapacitor purposes. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.