Browsing by Author "Dipika Meghnani"

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Conducting Carbon Rich Graphitic Carbon Nitride Nanosheets with Attached Nano Sulfur Copolymer as High Capacity Cathode for Long-Lifespan Lithium-Sulfur Battery
(John Wiley and Sons Inc, 2022) Rupesh K. Tiwari; Shishir K. Singh; Nitin Srivastava; Raghvendra Mishra; Dipika Meghnani; Anupam Patel; Anurag Tiwari; Vimal K. Tiwari; Rajendra K. Singh
A mesoporous, conducting, high specific surface area, carbon-rich graphitic carbon nitride (GCN) nanosheets host covered by nano sulfur copolymer has been reported as a cathode material that shows high capacity along with long cyclability for rechargeable lithium-sulfur batteries (LiSBs). The thermal pyrolysis technique has been used for carbon-rich GCN sheets synthesis, and the chemical deposition approach has been used to attach surface nanoparticles to the sheets. Further, to improve the binding of nano sulfur with host material, copolymerization of nano sulfur is carried out with help of 1,3-diethynylbenzene (DEB) monomer through the solution route. The sulfur nanoparticles are loaded on conducting carbon-rich GCN framework for fast electro kinematics and further copolymerization of sulfur nanoparticles is done to prevent the dissolution of the active material (sulfur) into the electrolyte during the charging/discharging for high capacity and long cycle life rechargeable LiSBs cathode preparation. The synthesized composite with high sulfur loading (∼76 wt.% of composite cathode material) as cathode shows an initial discharge capacity of ∼1380 mAh g−1 at 0.1 C and a good discharge capacity of ∼700 mAh g−1 after 1000 cycles at 1 C with ultra-low-capacity fading ∼0.016 % of the initial capacity in each cycle. © 2022 Wiley-VCH GmbH.
Development of gel polymer electrolyte based on LiTFSI and EMIMFSI for application in rechargeable lithium metal battery with GO-LFP and NCA cathodes
(Springer New York LLC, 2019) Liton Balo; Himani Gupta; Shishir K. Singh; Varun K. Singh; Alok K. Tripathi; Nitin Srivastava; Rupesh K. Tiwari; Raghvendra Mishra; Dipika Meghnani; Rajendra K. Singh
In this paper, we report the effect of ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI) on polymer poly(ethylene oxide) (PEO) and salt lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) electrolyte system. The glass transition temperature and degree of crystallinity decreased with an increasing amount of EMIMFSI resulting in an increase in the ionic conductivity. The highest room temperature ionic conductivity and Li+ transference number are observed for PEO + 20 wt% LiTFSI + 10 wt% EMIMFSI. These prepared gel polymer electrolytes (GPEs) are thermally and electrochemically stable enough for battery application. Two different cells with graphene oxide-doped lithium iron phosphate, LiFePO4 (GO-LFP) and lithium nickel cobalt aluminum oxide, LiNi0.80Co0.15Al0.05O2 (NCA) cathodes were tested with prepared GPEs. GO-LFP showed more predictable and consistent nature of capacity fading and good discharge capacity. However, NCA showed higher discharge capacity, better cyclic performance, lower capacity fading, and better performance at high C rates. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Development of polymer electrolyte and cathode material for Li-batteries
(Electrochemical Society Inc., 2019) Himani Gupta; Shishir K. Singh; Varun K. Singh; Alok K. Tripathi; Nitin Srivastava; Rupesh K. Tiwari; Raghvendra Mishra; Dipika Meghnani; Rajendra Kumar Singh
Enhancing the capacity and energy density of Li-battery along with maintaining its cycle life is the major challenge for electrochemical devices. Focusing on the positive electrode of Li-battery, specific capacity and cycle life of the layered oxide active material is studied thoroughly. On comparing their properties it could be found that Ni-rich layered oxide cathode materials give the best performance in terms of specific capacity and energy density but LiNi0.6Mn0.2Co0.2O2 cathode provides good capacity along with sufficient cycling performance. So, it is optimized as cathode material with our prepared ionic liquid (IL) based polymer electrolyte for Li cell. The structure and morphology of synthesized cathode material along with the electrochemical performance of polymer electrolyte and cell are investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical analyzer. Good specific discharge capacity (∼137 mAh g-1) and cyclability (upto 150 cycles) of the cell is observed. Experimental results suggest that the synthesized polymer electrolyte and cathode material is a promising candidate for Li battery. © The Author(s) 2018. Published by ECS.
Diffusion mechanism in a sodium superionic sulfide-based solid electrolyte: Na11Sn2AsS12
(Institute of Physics, 2022) Anurag Tiwari; Shishir K. Singh; Nitin Srivastava; Dipika Meghnani; Raghvendra Mishra; Rupesh K. Tiwari; Anupam Patel; Himani Gupta; Vimal K. Tiwari; Rajendra K. Singh
Recently, in all solid-state batteries, sulfide-based solid electrolytes have received increased attention due to their high ionic conductivity, good mechanical features, and better chemical stability. Therefore, in the present study, we have synthesized a novel sodium superionic conducting sulfide-based inorganic solid electrolyte (Na11Sn2AsS12) using a solid-state reaction method. The prepared solid electrolyte (Na11Sn2AsS12) is characterized by different techniques such as x-ray diffractometry (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy, thermogravimetric analysis (TGA), electrochemical impedance spectroscopy, and linear sweep voltammetry to study its various properties such as structure, surface morphology, thermal stability, dielectric properties, ionic conductivity, and electrochemical stability window for sodium ion battery (SIB) applications. The XRD analysis confirms two coexisting phases - tetragonal and cubic, with phase fractions of 0.69 and 0.31, respectively. The SEM study reveals the irregular shape and dense morphology of the solid electrolyte. On the other hand, TGA shows that the prepared solid electrolyte is suitable for high temperature battery applications. The ionic and transport studies confirm that the synthesized Na11Sn2AsS12 is purely ionic in nature, with ionic conductivity found to be 1.14×10-4 S cm-1 and negligible electronic conductivity 1/4 1.43×10-10 S cm-1 at room temperature. Furthermore, the detailed ionic conduction mechanism is studied using temperature and frequency-dependent AC impedance analysis. In addition, the synthesized solid electrolyte Na11Sn2AsS12 exhibits a wide electrochemical window ( 1/47.0 V) and a high diffusion coefficient ( 1.3×10-7 cm2 s-1) showing suitable electrolyte properties for solid-state SIB applications. © 2022 IOP Publishing Ltd.
Electrochemical investigation of double layer surface-functionalized Li-NMC cathode with nano-composite gel polymer electrolyte for Li-battery applications
(Elsevier Ltd, 2022) Shishir K. Singh; Dimple P. Dutta; Himani Gupta; Nitin Srivastava; Raghvendra Mishra; Dipika Meghnani; Rupesh K. Tiwari; Anupam Patel; Anurag Tiwari; Rajendra K. Singh
A long cycle-stability and safety is key requirement for the large-scale application of rechargeable Li-batteries. In this study, a thin double-layer (reduce graphene oxide and Li2MoO4) coated Li-NMC111 cathode is successfully synthesized which delivers improved electrochemical performance such as higher specific energy density and better rate capability, as compared to the pristine Li-NMC111. Furthermore, a freestanding/flexible nano-composite gel polymer electrolyte (NGPEs) is successfully prepared by solution cast technique and found suitable for high-temperature Li-battery applications. The developed 5 wt.% MCM-41 containing NGPE (NGPE#1) not only facilitates enhanced Li-ion conductivity of ∼4.4 ✗ 10−3 S cm−1 at 30 °C but also prevents uncontrolled lithium dendrite growth. The RGO-wrapped Li2MoO4@Li-NMC111 cathode with optimized NGPE#1 delivers high specific discharge capacity (∼211 mAh g − 1 at 0.2C and ∼157 mAh g − 1 at 0.5C) and specific energy density (∼728 mWh g − 1 at 0.2C and ∼520 mWh g − 1 at 0.5C) as compared to pristine Li-NMC111 cathode. Moreover, after 100 cycles, the discharge capacity of RGO-wrapped Li2MoO4@Li-NMC111 with optimized NGPE#1 is obtained ∼150 mAh g − 1 at 0.5C, with 75% capacity retention of the maximum capacity. In addition, at 70 °C, the specific discharge capacity of Li/RGO-wrapped Li2MoO4@Li-NMC111 cell with optimized NGPE#1 is obtained ∼186 mAh g − 1 at 0.5C. © 2022 Elsevier Ltd
Electrochemical Performance of High-Valence Mo6+ and Low-Valence Mn2+ Doped- Na3V2(PO4)3@C Cathode for Sodium-Ion Batteries
(John Wiley and Sons Inc, 2022) Dipika Meghnani; Shishir Kumar Singh; Nitin Srivastava; Rupesh Kumar Tiwari; Raghvendra Mishra; Anupam Patel; Anurag Tiwari; Rajendra Kumar Singh
The sodium superionic conductor (NASICON)-Na3V2(PO4)3 (NVP) is an attractive cathode for sodium-ion batteries, which is still confronted with limited rate performance due to its low electronic conductivity. In this paper, a chemical strategy is adopted to partially replace V3+ of the NVP framework by low-valence Mn2+ and high-valence Mo6+ substitution. The crystal structure, sodium-ion diffusion coefficient and electrochemical performance of Mn−Mo-doped [Na3.94V0.98Mo0.02Mn(PO4)3@C] cathode were investigated. X-ray diffraction confirmed the NASICON-type structure and XPS analysis confirmed the oxidation state of Mn and Mo in doped NVP cathode. The Na ion diffusion processes were inferred from Cyclic Voltammetry (CV), Galvanostatic intermittent titration technique (GITT) and Electrochemical Impedance Spectroscopy (EIS) measurement, which clearly show rapid Na-ion diffusion in NASICON-type cathode materials. The Mn−Mo-substituted NVP shows smoother charge-discharge profiles, improved rate performance (64.80 mAh/g at 1 C rate), better energy density (308.61 mWh/g) and superior Na-ion kinetics than that of unsubstituted NVP@C cathode. Their enhanced performance is attributed to large interstitial volume mainly created by high valence Mo6+ and enhanced capacity is attributed to the low valence Mn2+ doping. These results demonstrate that Mn−Mo-doped NVP cathode is strongly promising cathode material for sodium-ion batteries. © 2022 Wiley-VCH GmbH.
Electrochemical performance of Li-rich NMC cathode material using ionic liquid based blend polymer electrolyte for rechargeable Li-ion batteries
(Elsevier Ltd, 2020) Nitin Srivastava; Shishir Kumar Singh; Himani Gupta; Dipika Meghnani; Raghvendra Mishra; Rupesh K. Tiwari; Anupam Patel; Anurag Tiwari; Rajendra Kumar Singh
In this paper, synthesis of lithium rich nickel manganese cobalt oxide cathode material (Li1·2Ni0·6Mn0·1Co0·1O2) and ionic liquid (IL) based blend gel polymer electrolytes (BGPEs) are reported. Li1.2Ni0.6Mn0.1Co0.1O2 cathode material as well as BGPEs are prepared by solution combustion and solution casting technique, respectively. X-ray diffraction (XRD) technique clearly reveals that the cathode material is in pure phase, having well defined layered structure. Thermal, electrical and electrochemical properties of BGPEs are investigated by using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), impedance spectroscopy and linear sweep voltammetry (LSV). It is observed that 70 wt% IL containing BGPE provides maximum Li-ion conductivity (σLi∼1.1 mS cm−1), thermal (∼250 °C) and electrochemical stability (∼4.3 V vs. Li/Li+). Electrochemical analysis of the cell (Li/70 wt% BGPE/Li1·2Ni0·6Mn0·1Co0·1O2) provides well defined redox peaks corresponding to Ni2+/Ni4+ and it delivers specific discharge capacity of 166 mAh g−1 at 0.1 C-rate and 97% efficiency upto 140 cycle. © 2020 Elsevier B.V.
Enhanced Cyclic Stability of LiNi0.815Co0.15Al0.035O2 Cathodes by Surface Modification with BiPO4 for Applications in Rechargeable Lithium Polymer Batteries
(John Wiley and Sons Inc, 2021) Dipika Meghnani; Himani Gupta; Shishir K. Singh; Nitin Srivastava; Raghvendra Mishra; Rupesh K. Tiwari; Anupam Patel; Anurag Tiwari; Rajendra K. Singh
The effect of incorporating the ionic liquid (IL) N-methyl-N-propyl piperidinium bis(fluorosulfonyl)imide (PP13FSI) to a polymer electrolyte (PE) based on the polymer poly(ethylene oxide) (PEO)- lithium bis(fluorosulfonyl)imide (LiFSI) [PEO+20 wt.% LiFSI] is investigated. The concentration of PP13FSI IL is varied from 10 to 40 wt.% in the PEO+20 wt.% LiFSI system and the influences of the ionic conductivity, thermal stability, diffusion coefficient, and electrochemical stability are studied. The 40 wt.% IL containing PE shows good thermal stability ∼210 °C and high ionic conductivity, (Formula presented.), at 40 °C with a wide electrochemical stability window ∼4.7 V vs. Li/Li+ and high (Formula presented.) at 30 °C. Furthermore, the electronic conducting BiPO4 is coated on the LiNi0.815Co0.15Al0.035O2 (BiPO4@NCA) cathode by the liquid precipitation method. To investigate the structural and electrochemical properties of the pristine and BiPO4@NCA cathodes, XRD, SEM, TEM, and DSC as well as the electrochemical method are employed. The XRD results reveal a hexagonal layered structure without any impurity phase in BiPO4@NCA. The TEM investigations show that the BiPO4 layer (∼10 nm) is homogeneously coated on the NCA particles. The electrochemical testing showed an improvement in the cyclic performance of BiPO4@NCA with a capacity retention 94.64 % after 150 cycles, which is 8 % greater than that of the pristine NCA. © 2021 Wiley-VCH GmbH
Fabrication and electrochemical characterization of lithium metal battery using IL-based polymer electrolyte and Ni-rich NCA cathode
(Springer Science and Business Media Deutschland GmbH, 2020) Dipika Meghnani; Himani Gupta; Shishir Kumar Singh; Nitin Srivastava; Raghvendra Mishra; Rupesh Kumar Tiwari; Anupam Patel; Anurag Tiwari; Rajendra Kumar Singh
Electrolytes with high Li+ transference number and good electrochemical stability are urgently needed for high-energy-density Li battery. In this paper, we present newly synthesized ionic liquid (IL)-based polymer electrolyte using polymer poly(ethylene oxide) (PEO), salt lithium bis(fluorosulfonly)imide (LiFSI), and IL 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide (BMPyTFSI) by solution cast technique. They show high Li+ transference number and good electrochemical and thermal stability. Also, nickel-rich layered cathode material LiNi0.90Co0.05Al0.05O2 (NCA) with good electrochemical performance for lithium secondary battery is successfully synthesized by Co-precipitation method. Using the optimized polymer electrolyte and NCA cathode, Li cell is prepared which shows initial discharge capacity of ~ 137 mAh g−1 at 0.1 C-rate and good Coulombic efficiency ~96.0% upto 125 cycles. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
High-Voltage-driven Li/Mn-rich Li1.2Mn0.6Ni0.1Co0.1O2 Cathode with nanocomposite blend gel polymer electrolyte for long cyclic stability of rechargeable Li-battery
(John Wiley and Sons Inc, 2022) Nitin Srivastava; Shishir Kumar Singh; Dipika Meghnani; Rajendra Kumar Singh
Li/Mn-rich layered oxide is an attractive cathode material for Li-ion battery due to its low cost, high specific capacity, and high working potential. In this paper, the high capacity layered Li/Mn-rich NMC cathode (Li1.2Mn0.6Ni0.1Co0.1O2) and nanocomposite blend gel polymer electrolytes (NBGPEs) are synthesized by using the sol-gel method and solution casting technique, respectively. XRD results confirm that the cathode material has a well-defined hexagonal layered structure. It is observed that the synthesized NBGPE containing 2 wt.% SiO2 nanofiller exhibits maximum ionic conductivity (5.2 mS cm−1), Li-ion conductivity (~2.40 mS cm−1), and wide electrochemical stability (~5.4 V vs Li/Li+) at 30°C. The electrochemical performance of the cell (Li/NBGPE#1/Li1.2Mn0.6Ni0.1Co0.1O2) has been investigated by cyclic voltammetry and galvanostatic charge–discharge measurement. The cell delivers maximum specific discharge capacity of 212.0 mAh g−1 at 0.1C and good rate performance within 2.0-4.8 V. At 0.2C, the cell shows stable coulombic efficiency ~98% after 200th cycle due to better interfacial stability between NBGPE#1 and the electrode. © 2022 John Wiley & Sons Ltd.
Impact of sintering temperature and ascertaining hopping bottlenecks for ions in sodium superionic conducting electrolyte for sodium-ion batteries
(Elsevier B.V., 2023) Anurag Tiwari; Dipika Meghnani; Raghvendra Mishra; Rupesh Kumar Tiwari; Anupam Patel; Rajendra Kumar Singh
Recently, sodium super-ionic conducting (NASICON) type solid electrolytes have gained attention for next generation batteries because of their high ionic conductivity, low cost, excellent chemical and electrochemical stability. Therefore, in the present study, NASICON-type solid electrolyte Na3Zr2Si2PO12 is synthesized by solution assisted-solid state reaction (SA-SSR) route. The electrolytes are sintered at three different temperatures, 1200 °C, 1250 °C and 1300 °C. The sintered electrolytes are characterized by various experimental techniques. The Rietveld refinement of X-ray diffraction pattern of prepared electrolytes revealed the monoclinic crystal structure. The 3-dimension hopping channel for sodium ion migration through triangular bottleneck area is identified. From complex impedance spectroscopy measurement, the highest bulk and grain boundary conductivity are found, ∼4.05mScm−1 and ∼0.31mScm−1, respectively, for the sample sintered at 1250 °C. The optimized electrolyte shows wide electrochemical stability (∼6.5 V) which is suitable for high voltage battery application. Using optimized electrolyte, sodium half-cell is fabricated with sodium metal as anode, and Na3V2P3O12 (NVP) as cathode. The assembled cell delivers maximum discharge capacity ∼101.6 and ∼84.5mAhg−1 at the current density 10 and 40mAg−1, respectively with good capacity retention (∼95.02%) upto 50 cycles. © 2023 Elsevier B.V.
Improved High Voltage Performance of Li-ion Conducting Coated Ni-rich NMC Cathode Materials for Rechargeable Li Battery
(American Chemical Society, 2021) Himani Gupta; Shishir K. Singh; Nitin Srivastava; Dipika Meghnani; Rupesh K. Tiwari; Raghvendra Mishra; Anupam Patel; Anurag Tiwari; Achchhe L. Saroj; Rajendra Kumar Singh
Recently, in lithium batteries, high-capacity Ni-rich cathode materials (LiNi0.8Mn0.1Co0.1O2) have gained tremendous attention. However, they also suffer from serious capacity degradation upon cycling, particularly at high voltage. To solve this problem, two strategies are proposed. The first one is the surface modification on the NMC811 cathode material with Li-ion-conducting Li3PO4. The second is the use of IL-based gel polymer electrolytes in Li metal batteries. Li3PO4 coating not only maintains the structure stability of the cathode but also suppresses the side reaction at the electrode-electrolyte interface. It also improves the Li+ ion conduction in the cathode material. Furthermore, in order to avoid the sensitivity of the cathode material toward H2O, CO2, and HF attack and solubility of transition metal ions in the electrolyte and enhance the cyclic performance of the Li battery, an IL-based gel polymer electrolyte is used. Mechanical stability of the polymer electrolyte can help suppress the lithium dendrite growth and overcome the issues of low electrochemical stability, leakage, and corrosion in liquid electrolytes. Electrochemical performance of the Li3PO4-coated NMC cathode material with the gel polymer electrolyte is tested at higher and lower upper cutoff voltages. Li batteries show a high discharge capacity of ∼182 mA h/g and an energy density of 606 mW h g-1 at C/10 current rate with almost stable cyclic stability up to 300 cycles. These tremendous features of polymer-based batteries with a surface-modified cathode material highlight its promising application in next-generation Li batteries. ©
Influence of synthesis route on the structure and electrochemical performance of biphasic (O'3/O3) NaNi0.815Co0.15Al0.035O2 cathode for sodium-ion batteries
(Elsevier Ltd, 2022) Dipika Meghnani; Rajendra Kumar Singh
Sodium-ion batteries have gained widespread attention for energy storage devices because of low cost and high abundance of sodium sources. In this paper, Biphasic O'3/O3 layered NaNi0.815Co0.15Al0.035O2 cathode materials (Na-NCA) are synthesized by using three different chemical routes viz. coprecipitation, hydrothermal and sol-gel methods. X-ray diffraction pattern and Raman analysis show the clear evidence of layered structure of all three samples. The kinetics of sodium ion [Na+] is deduced from cyclic voltammetry techniques and the values of Na+ ion diffusion coefficient is found to be 1.62×10−12, 1.11×10−13 and 1.71×10−12cm2s−1 for Na-NCA synthesized by coprecipitation, sol-gel and hydrothermal methods, respectively implying the better kinetics of Na+- ions in hydrothermal prepared Na-NCA cathode. Furthermore, the Cyclic voltammetry and differential capacity versus voltage (dQ/dV vs.V) studies reveal the good reversibility of phase transition in cathode prepared using hydrothermal route. Electrochemical testing indicates the better performance of hydrothermally prepared Na-NCA in terms of discharge capacity, capacity retention and energy density. This improved electrochemical performance is attributed to decease in solid electrolyte interface, reversible phase transition and high surface area as well as better diffusion coefficient. Additionally, evolution of phase after cycling process are also investigated and only single O'3 phase is observed for hydrothermal prepared Na-NCA cathode which is highly stable at room temperature. © 2022 Elsevier Ltd
Mitigating the Capacity Degradation by Ion-Electron-Conducting Dual-Layer Coating on a Layered Oxide Cathode Material for Sodium Ion Batteries
(American Chemical Society, 2023) Raghvendra Mishra; Shishir K. Singh; Nitin Srivastava; Rupesh K. Tiwari; Dipika Meghnani; Anupam Patel; Anurag Tiwari; Vimal K. Tiwari; Rajendra K. Singh
A high-capacity and long-life layered P2-Na0.7[Ni0.35Mn0.60Co0.05]O2 (NMC) cathode material, dually coated with Na-ion-conducting Na2SiO3 and electron-conducting RGO, has been successfully synthesized and tested for half-cell as well as full-cell applications. The first coating layer of Na2SiO3 provides a three-dimensional (3D) diffusion channel for Na-ion migration, while the second coating layer of RGO offers the electron-conducting pathways to enhance the charge transfer. Moreover, Si4+ migration in the NMC lattice during Na2SiO3 coating causes the enhancement in the interlayer spacing, which significantly increases the Na+-diffusion rate. The structural, morphological, electronic, and electrochemical analyses of the prepared cathode materials have been performed. The synergic effect of dual-layer modification and Si4+ doping not only protects the cathode particles but also improves the Na-ion kinetics as well as charge transfer rate, resulting in superior electrochemical performance. The dually surface-modified cathode shows a maximum discharge capacity of 171 mAh g-1 at ∼13 mA g-1 and 62 mAh g-1 at ∼1300 mA g-1 with 76% capacity retention and ∼98% coulombic efficiency over 500 cycles at 1C rate (260 mA g-1) for the half cell, while for the full cell, it delivers an initial discharge capacity of ∼91 mAh g-1 and 66% capacity retention over 1000 cycles at 1C rate. © 2023 American Chemical Society.
Molybdenum-Doped Li/Mn-Rich Layered Transition Metal Oxide Cathode Material Li1.2Mn0.6Ni0.1Co0.1O2with High Specific Capacity and Improved Cyclic Stability for Rechargeable Li-Batteries
(American Chemical Society, 2022) Nitin Srivastava; Shishir Kumar Singh; Dipika Meghnani; Raghvendra Mishra; Rupesh Kumar Tiwari; Anupam Patel; Anurag Tiwari; Rajendra Kumar Singh
A series of cathode materials, Li1.2Mn0.6-xNi0.1Co0.1MoxO2 (x = 0, 0.005, and 0.01), are synthesized via the sol-gel method. Structural characterization revealed that the Mo-doped material shows a well-defined ordered layered structure having less cation mixing. The Li1.2Mn0.59Ni0.1Co0.1Mo0.01O2 (LMRMo#0.01) cathode shows a high specific discharge capacity of 193.9 mAh g-1 with an initial Coulombic efficiency of 81.4% at room temperature and an excellent cyclic stability with a discharge capacity of ∼175.3 mAh g-1 (capacity retention 92.5%) after 250 cycles at 0.1 C. Substitution of Mn4+ by Mo6+ leads to low charge transfer resistance and enhancement in the stability of the layered structure, which result in outstanding electrochemical performance of the Mo-doped cathode. © 2022 American Chemical Society.
Multifaceted ethylenediamine and hydrothermal assisted optimum reduced GO-nanosulfur composite as high capacity cathode for lithium-sulfur batteries
(John Wiley and Sons Inc, 2022) Rupesh K. Tiwari; Shishir K. Singh; Himani Gupta; Nitin Srivastava; Dipika Meghnani; Raghvendra Mishra; Anupam Patel; Anurag Tiwari; Vimal K. Tiwari; Rajendra K. Singh
A high specific capacity conducting reduced graphene oxide nanosulfur nanocomposite (RGOSNC) cathode is synthesized via deposition of nanosulfur on graphene oxide (GO) through the hydrothermal treatment in the presence of multifaceted ethylenediamine (EDA) for improving the performance of lithium-sulfur battery (LiSB). The maximum utilization of active material (sulfur) is facilitated by the attachment of nanosulfur to GO via EDA, and further, optimum reduction of GO into conducting, porous and interconnected RGO is performed via hydrothermal treatment in the available solution having residual EDA. Therefore, GO is reduced in highly conducting RGO without the use of any external reducing agent; minimizing the chance of impurity in the synthesized RGOSNC. A three-dimensional interconnected porous conducting architecture with nitrogen (heteroatom) doping in RGO of RGOSNC with conductivity ∼1.83 S/cm assists easy electron transportation through conducting RGO network and stabilizes intermediate polysulfide to prevent loss of active material during the electrochemical performance. The synthesized RGOSNC cathode material delivers high initial specific capacities 1448 and 1040 mAh/g at 0.1 and 0.5 C, respectively. Prepared LiSB maintains ∼741 mAh/g retention over 100 cycles at 0.5 C with excellent Coulombic efficiency (∼99%). © 2021 The Authors. Electrochemical Science Advances published by Wiley-VCH GmbH.
Phosphite-Based Electrodes
(American Chemical Society, 2022) Dipika Meghnani; Shishir Kumar Singh; Nitin Srivastava; Rajendra Kumar Singh
Theoretical Understanding to Design a Better Solid-State Battery. Solid-state batteries have the potential to significantly improve the safety and performance of current state-of-the-art lithium-ion battery technology. They find applications in automobile and electronic industries; however, most commercial lithium-ion batteries are flammable, and their decomposition generates highly toxic gasses that can be explosive. These two volumes (1413 and 1414) provide an overview of fundamental mechanisms, current challenges, and design strategies for solid-state batteries to meet the current demands for commercialization. This volume focuses on materials, advanced batteries, and the architecture of flexible and printable batteries. These volumes should interest chemists and materials scientists working on energy challenges. © 2022 American Chemical Society. All rights reserved.
Physical, thermal and electrochemical properties of ionic liquid plasticized gel polymer electrolytes
(Nova Science Publishers, Inc., 2021) Dipika Meghnani; Dimple Dutta; Rajendra Kumar Singh
The energy crises have become a critical issue over the worldwide and increasing energy demand motivates the researcher for developing efficient energy storage devices to get continuous energy supply from intermittent renewable sources like solar, wind, etc. In this perspective, rechargeable lithium batteries have gained much attention because of having high capacity and energy density. Although, in rechargeable batteries, electrolyte plays a major role in determining the electrochemical performance of batteries as provides the ion conduction path between the electrodes. In batteries, mostly liquid electrolytes are used because of having high conductivity and low electrode-electrolyte interfacial resistance. However, these electrolytes suffer some major problems like high reactivity towards electrode and formation of spiny projection in case of metal electrode. Besides, some safety issues such as leakage, corrosion, volatility, explosion, etc. have also been reported. To suppress these problems, solid electrolytes have been preferred over liquid electrolytes. But the solid electrolytes suffer from high interfacial resistance as well as low flexibility. Therefore, in order to overcome the above said problems, ionic liquid (IL) based gel polymer electrolytes are used which possess high flexibility, mechanical and thermal stability, wide electrochemical window. Ionic liquids (ILs) also plasticize the polymer electrolyte matrix and hence ionic conductivity is increased. Further, unlike conventional plasticizers, ILs have negligible vapour pressure and hence electrolyte remains amorphous over extended period. The desired properties of IL based gel polymer electrolytes make them most suitable for battery application. This chapter introduces physical, thermal and electrochemical properties of IL based polymer electrolyte and their applications in rechargeable lithium batteries. © 2021 Nova Science Publishers, Inc.
Polar β-Phase PVdF-HFP-Based Freestanding and Flexible Gel Polymer Electrolyte for Better Cycling Stability in a Na Battery
(American Chemical Society, 2021) Raghvendra Mishra; Shishir K. Singh; Himani Gupta; Rupesh K. Tiwari; Dipika Meghnani; Anupam Patel; Anurag Tiwari; Vimal K. Tiwari; Rajendra K. Singh
The stable polar gel polymer electrolyte (GPE) of sodium salt and ionic liquid (IL) incorporated in the PVdF-HFP (polyvinylidine fluoride-co-hexafluoropropylene) matrix at high loading was synthesized for improved performance of the sodium battery. The 1 M sodium bis trifluoromethylsulfonyl imide salt (S) in 1-butyl-3-methylimidazolium bis trifluoromethylsulfonyl imide IL used to prepare salt-IL (SIL) solution was mixed with PVdF-HFP at different weight percentages to prepare polar GPE films. The polar β-phase PVdF-HFP in the GPE is generated by the incorporation of the above-prepared SIL. The temperature- and frequency-dependent ionic conductivities with a scaling approach and dielectric relaxation analysis have been carried out for the prepared GPEs. The 70 wt % SIL containing GPE (PSIL70) shows excellent thermal stability up to 368 °C, high ionic conductivity (1.9 × 10-3S cm-1at 30 °C), and sodium-ion transference number ∼0.27 with a wide electrochemical stability window (4.2 V vs Na/Na+at 30 °C). The optimized electrolyte PSIL70 is used to fabricate coin cell (Na/PSIL70/Na-NMC) with the prepared Na-NMC cathode and Na-metal anode. The charge-discharge result shows that the specific discharge capacity of the cell is ∼108 mA h g-1at 0.1 C (21 mA g-1). The capacity retention is 94% over 200 charge-discharge cycles at 0.2 C, showing high capacity with good retention for the sodium battery. © 2021 American Chemical Society
Polymer nanocomposite dielectrics for high-temperature applications
(wiley, 2022) Dipika Meghnani; Rajendra Kumar Singh
Polymer nanocomposites dielectric have been widely used in energy storage system as they have enhanced dielectric performance. The polymer nanocomposites have been configured by integrating nanoparticle, which has high permittivity and the polymer matrix of high electric breakdown strength (Ed). This integrates the merit of both polymer and nanoparticle into the polymer nanocomposite, improving its dielectric properties at elevated temperature too. Polymer nanocomposite has advantages of good mechanical properties, high Ed, good processability, and excellent dielectric and capacitive properties at high temperature. This chapter represents the current advantages of polymer nanocomposite dielectric at elevated temperature in the field of aerospace industry, hybrid electric vehicles (HEVs), automotive, packaging industry, etc. Also, the crucial parameters in modeling the high-temperature polymer nanocomposites are emphasized along with their applications © 2022 Scrivener Publishing LLC. All rights reserved.