Browsing by Author "Dipti Yadav"

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Economical, ecofriendly and easy to handle polymer-in-salt-electrolyte
(Elsevier B.V., 2025) Dipti Yadav; Kanak Aggarwal; Neelam Srivastava
Polymer-In-Salt-Electrolytes (PISEs) are an emerging branch of polymer electrolytes which are supposed to address the shortcomings (slow ion movement due to polymer coupled motion and small cationic transference number) of Salt-In-Polymer-Electrolytes (SIPEs), but a PISE, which may be commercially used for fabrication of energy device is still a dream because of recrystallization and brittle matrix at higher salt concentration. Our group has developed a simple solution casting protocol for synthesis of an economical, eco-friendly and easy to handle PISEs from crosslinked starches, where there is no need of getting the molten state salt/salt-mixture. The thought process behind this protocol and selection of starch as host polymer is that the salt breaks the starch into smaller molecules resulting in generation new –OH and –H to interact with salt, i.e. increasing salt concentration itself creates a favorable atmosphere for its acceptance. Starch is hydrophilic in nature and presence of large amount of salt adds up to it, and such materials have moisture content varying from ∼5 % to 25 %, depending to salt and starch combination and concentration, which is a favorable property leading the synthesized PISEs to behave as Water-In-Polymer-Salt-Electrolytes (WiPSEs). By exposing the freshly synthesized samples to high humidity these materials were stabilized with respect to ambient humidity changes. These materials lead to ESR <10 Ω (reaching to as low as <1 Ω), wide electrochemical stability window (ESW > 2.5 V) and ion relaxation time is of the order of μSec. The supercapacitor fabricated using synthesized PISEs with commonly available supercapacitor electrodes have behavior at par with other electrolytes reported in the literature. With lab-synthesized activated carbons, a capacity of ∼125 F/g has been obtained with columbic efficiency >98 %. Since the synthesis protocol and chemicals used are economical, the starch-based PISEs are economical and also environment benign, because starch is a renewable polymer and the process uses only one extra chemical (methanol as solvent). The material is flexible and can be molded in the desired shape and size and hence is a potential candidate to reach at the commercial level, if explored in detail. © 2025
Effect of crosslinker on the electrochemical properties of starch-based water-in-polymer-salt electrolytes
(Springer Science and Business Media Deutschland GmbH, 2024) Dipti Yadav; Amrita Pandey; Neelam Srivastava
Water-In-Polymer-Salt-Electrolytes (WiPSEs) are identified as the highly conductive electrolytes (~0.01 S/cm) with wide electrochemical stability window (ESW) for the advanced energy storage devices. In our previous reports, we reported that cross-linked starches are good hosts for Polymer-In-Salt-Electrolytes (PISEs) synthesis and by exposure to high humidity atmosphere, it behaves like WiPSE. In the present study, our effort is to understand the effect of change in bonding structure on the mechanical and electrochemical properties of these materials. Hence, in the present case we have varied both, the salt concentration and the crosslinker amount, because crosslinker amount is supposed to enrich the covalent bonding and hence water absorption through hydrogen bonding will be negatively affected. Effect of crosslinking variations of GA (1- to 5-ml Glutaraldehyde for 1-g starch) is studied at three varied salt concentrations (50, 66, 75 wt % salt). Highest conductivity is found to be ~0.03 S/cm with ESW of ~2 V with flexible morphology. Further, a supercapacitor is fabricated by using 75 wt % salt WiSPE with coated carbon cloth-based electrodes. Specific capacitance is of order of 10 F/g at 10 mV/s scan rate with coulombic efficiency greater than ~85%. This work confirms the theoretical understanding that loosely bound structures are better for PISEs/WiPSEs. Being economical and environment-friendly, these electrolytes have the potential to reach commercial level if explored in detail. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
Effect of High Humidity Exposure to Wheat Starch Based High Conducting Flexible Polymer-in-Salt-Electrolyte
(John Wiley and Sons Inc, 2024) Dipti Yadav; Shreya Basuroy; Rakesh Kumar; Kanak Aggarwal; Neelam Srivastava
Polymer-in-salt-electrolytes (PISEs) are an important class of electrolytes as they carry the promise of faster and single ion transport. Unfortunately, due to unavailability of a suitable polymer host PISE has still not reached to commercial level. In the present work, using a novel synthesis protocol developed by the group, glutaraldehyde crosslinked wheat starch has been successfully modified with sodium iodide (NaI) to synthesize a flexible PISE membrane with desired electrochemical properties. Present paper reports the effect of crosslinker and exposure to high humidity ambience on electrochemical and morphological properties. It has been established that on exposure to higher humidity atmosphere starch-based PISEs stabilize at lower resistance value, but with higher ion relaxation time, which indicates that effect of high humidity treatment is more on salt dissociation instead of assisting the ion transport. The studied materials have conductivity ≈0.01 S cm−1 range with ESW >2.5 V, ensuring its usability in electrochemical devices. The developed synthesis protocol does not require any complicated synthesis route and/or sophisticated instrument hence the overall process is economical also, adding up to its potentiality for energy device fabrication. © 2024 Wiley-VCH GmbH.
High power density supercapacitor, using a fast ion conducting, flexible, economical, and environment benign polymer-in-salt-electrolytes (PISEs)
(Elsevier B.V., 2025) Dipti Yadav; Neelam Srivastava
High-performing supercapacitor requires high and fast ion conducting electrolytes with a wide Electrochemical Stability Window (ESW). Polymer-In-Salt-Electrolytes (PISEs), having diffusion type of ion transport, much faster than polymer coupled ion transport relative to traditional Salt-In-Polymer-Electrolytes (SIPEs), are one such possible electrolyte that can be used for supercapacitors. The present paper discusses the synthesis and characterization of a flexible, high ion conducting (σ ∼ 0.05 Scm−1), having fast ion movement (ion relaxation time (τ) ∼μSec), economical, easy to handle and environment benign PISEs, with wide ESW (∼6 V), whose properties are stabilized with respect to ambient humidity changes. The electrolytes are synthesized by adding magnesium nitrate (Mg (NO3)2) to glutaraldehyde (GA) crosslinked corn starch using the solution cast technique. The work also discusses the effect of the lattice energy of salt on the mechanical and electrochemical properties of electrolytes. The fabricated supercapacitor has a specific capacitance of ∼750 Fg-1 and power density ∼2 kW kg−1, having coulombic efficiency >95 %. The Ragone plot has indicated that the device is in the Ultracapacitor range. Fabricated supercapacitor (∼25 cm2 area) is capable of glowing a Light Emitting Diode (LED) for ∼3 min, proving its potential as an electrolyte for future commercial energy storage devices. © 2025 Elsevier B.V.
Investigating Ca2+ salt–based polymer-in-salt electrolyte for future energy storage systems
(Springer Science and Business Media Deutschland GmbH, 2024) Kanak Aggarwal; Dipti Yadav; Kashish Tiwari; Pushpa Kushwaha; Neelam Srivastava
The scientific community is continuously putting efforts to improve the energy/power density of energy storage devices, which leads to development of novel materials with enhanced electrochemical properties. Polymer-in-salt electrolytes (PISEs) are expected to have faster ion transport and hence may result in improved power density. In the present study, Ca salt–based PISE is synthesized using glutaraldehyde (GA)–crosslinked arrowroot starch as host matrix. The synthesized PISE has high conductivity (~ 0.01 S/cm), wide electrochemical stability window (ESW > 3 V), and small characteristic relaxation time (τ ~ 17 µs) indicating the possibility of faster response in any device fabricated using synthesized PISEs. Fabricated supercapacitor, using the highest conducting PISE with rGO as electrode, has specific capacitance ~ 17 F/g at 1 mV/s and high power density 2.1 kW/kg with coulombic efficiency (CE) of > 90.05% and with CAC as electrode, specific capacitance ~ 125 F/g at 1 mV/s and high power density 2.1 kW/kg with coulombic efficiency (CE) of > 99%. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
NaClO4 added, corn and arrowroot starch based economical, high conducting electrolyte membranes for flexible energy devices
(Springer Nature, 2020) Jagdish Kumar Chauhan; Dipti Yadav; Madhavi Yadav; Manindra Kumar; Tuhina Tiwari; Neelam Srivastava
The increasing flexible and wearable electronic technology, demands cost effective and flexible energy devices which are safe to human body. Hence the benign biodegradable materials are becoming important class of materials for wearable energy devices. Starch is one such potential host renewable polymer which is abundant in nature and economical. Being a food ingredient, it is safe for human body. Its properties depends upon the amylose and amylopectin content in it and hence two different starches, corn (~ 27% amylose) and arrowroot (~ 15% amylose) are modified by sodium salt (NaClO4) and glutaraldehyde to develop flexible, transparent and free standing electrolyte membranes with high conductivity (> 10–3 S/cm). They have wide electrochemical stability window (> 2 V reaching upto 3.5 V) and low ESR. The relaxation time is of the order of µs and the cyclic voltammetry has indicated EDLC type of charge storage. At low frequency, the values of Cp/Cs are approaching to 1, indicating that all the available charges are polarizable and contributing to charge storage. The resonance frequency and frequency (f−45°) at which phase angle is −45°, are in kHz frequency range, i.e. the working frequency range is quite high. Electrolytes having corn starch (i.e. greater amount of amylose) have better performance on every electrochemical figure of merit. © 2020, Springer Nature Switzerland AG.
Polysaccharide Biomaterials for Electrochemical Applications
(wiley, 2023) Neelam Srivastava; Dipti Yadav
Today’s lifestyle and energy devices are synonyms to each other hence for sustainable developments optimum use of renewable energy sources is the only way out. For better utilization of renewable energy resources, efficient energy storage systems are obligatory. Unfortunately, excessive and inefficient use of energy storage system leads to environmental threat because they add up to global chemical garbage. Hence scientific community is optimistic towards renewable chemicals to replace the synthetic chemical components in energy devices. When such alternate options are sought to reach the commercial level then the cost effectiveness and abundance become an inevitable component. Polysaccharides, being abundant, cost effective and being available in variety, have allured electrochemists for its application as electrolyte, electrode, binder, separator etc. Variety of polysaccharides such as cellulose and its derivatives, chitosan/chitin, starch, alginate, gum, pectin, etc., have been successfully explored. Polymer-in-salt-electrolytes (PISEs) have also been successfully developed using polysaccharides. PISEs are the polymer electrolytes where amount of salt is beyond certain threshold so that ion motion is decoupled from polymer segmental motion and hence in such systems possibility of achieving single and fast ion transport is very high. Literature indicates that synthetic polymers have substantially failed to hold large amount of salt in dissociated form along with flexible morphology. Different methods of electrode preparation used with synthetic chemical as precursor are applicable to polysaccharides also. This chapter reviews the use of polysaccharides for electrochemical applications. © 2023 Scrivener Publishing LLC.
Supercapacitor performance of polymer-in-salt electrolyte/water-in-polymer salt electrolyte synthesized by complexing glutaraldehyde crosslinked corn starch with Mg(ClO4)2
(Springer Science and Business Media Deutschland GmbH, 2024) Dipti Yadav; Kamlesh Pandey; Kanak Aggarwal; Neelam Srivastava
Energy devices with high energy/power density are the need of the day, and to achieve the same, electrolytes with faster ion transport and wider electrochemical stability window are required. Polymer-in-salt electrolytes (PISEs) are predicted to have the better required electrochemical properties in comparison to salt-in-polymer electrolytes (SIPEs), but desired success is still to be achieved due to recrystallization problems. PISEs suffer from poor mechanical and/or electrochemical properties along with aging effects as well; hence, special efforts are required to reduce the crystallinity of PISEs. The present paper discusses a crosslinked corn starch complexed with Mg(ClO4)2 which not only has desired electrochemical properties but is also flexible. XRD study confirms the absence of crystalline nature, without any extra efforts to reduce it. Synthesized PISEs have high conductivity (~0.01 Scm−1), wide ESW (> 3 V), and low relaxation time (µs) along with being economical. Supercapacitors fabricated using this novel PISE with laboratory synthesized activated carbon (from leaves and corn starch) have shown good specific capacitance (~ 20 Fg−1 and ~ 45 Fg−1, respectively). The power density is of the order of kW kg−1, which is quite high in comparison to other reports. The shape of CV and LSV is strongly influenced by the salt concentration, i.e., by the ion-cluster size, and is also affected by the volume/size of the activated carbon pores. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
The effect of ceramic nanofillers on conductivity and ion-transport behavior in potato starch-based solid bio-polymer electrolyte for advanced energy storage devices
(Springer Science and Business Media Deutschland GmbH, 2025) Km Jyoti Rai; Deepash Shekhar Saini; Prashant Shahi; Sujeet Kumar Chaurasia; Dipti Yadav; Neelam Srivastava; Rishabh Mishra; Manindra Kumar
The solution cast method was used to synthesize the nanocomposite solid polymer electrolytes, which were composed of potato starch (PS) as the host polymer, sodium iodide (NaI) as an ion source, and dispersed with Ce-substituted cobalt ferrite (CoFe1.95Ce0.05O4). The nanocomposite solid polymer electrolyte was characterized using a variety of techniques, including electrical impedance spectroscopy (EIS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and its deconvolution, X-ray diffraction (XRD), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD). The maximum conductivity of 9.06 × 10−3 S/cm is attained for a system of 1.0 wt.% of Ce-substituted cobalt ferrite nanofillers. Inside the polymer matrix, the ion motion is triggered by the ceramic nanofillers. Therefore, the conductivity of the electrolyte was increased. The FTIR verified complexation behavior in the material. The deconvolution of FTIR spectra in the desired region yielded ion transport parameters, such as diffusion coefficient (D), mobility (µ), and carrier density (n). DSC thermograms indicate an endothermic process, and a broad melting peak at 60 °C is in the electrolyte system consisting of 50 wt.% NaI in potato starch due to the gelatinization of the starch granules, which is followed by another broad peak observed at 137 °C due to the dissociation of the material. TGA thermograms show multistage decomposition mechanisms with three processes. LSV and CV analyses indicate that the material is purely capacitive in nature and contains a broad electrochemical stability window, making it suitable for device applications. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.