Investigation of charge and current dynamics in PVA–KOH gel electrolyte-based supercapacitor

Abstract

Poly-vinyl alcohol (PVA)-based electrolytes can play a vital role in the development of supercapacitors by providing a desirable charge separator layer with an added advantage of stretchable nature. These properties enable them as a global contender in wearable electronics and charge storage applications. In this study, the PVA-based electrolyte has been synthesized with potassium hydrooxide (KOH) as ionic migration agent, which may enhance the electronic double-layers capacitance (EDLC) phenomena. In order to mechanically strengthen the graphene-based activated carbon, larger pore fabric is utilized for its encapsulation. Post-fabrication analysis of the supercapacitor using the standard imaging/microscopy techniques (scanning electron microscopy, electron-dispersive electroscope, and atomic force microscopy) are carried out as initial diagnostic test. For detailed electrical, optical, and charge-based evaluation, electrochemical impedance spectroscopy (EIS), Nyquist plot analysis, currentvoltage (I-V) measurements, charged deep-level transient spectroscopy (Q-DLTS), and photoluminescence spectroscopy (PLs) are performed. The fabricated supercapacitor took * 30 min to completely discharge itself at ''full load operation.'' The band diagram, at carrier transport levels, has also revealed the presence of two possible trap centers which may be responsible for the degradation and/or overall stability of the supercapacitor.

Ribbon-like Nickel Cobaltite with Layer-by-Layer-Assembled Ordered Nanocrystallites for Next-Generation All-Solid-State Hybrid Supercapatteries

“…29 Among various gel polymer electrolytes, polyvinyl alcohol (PVA)−KOH is most widely utilized in all-solid-state devices, where a basic electrolyte medium is the prime requirement. 30 This is because the PVA−KOH gel electrolyte can operate in a wide range of pHs, just like the aqueous electrolyte solutions, is not corroding for the electrode materials, serves as a mechanically strong elastic coating, possesses good affinity to hold the solvents, and can operate in a wider temperature window. The PVA−KOH gel also holds the advantages of excellent room-temperature ionic conductivity (up to 105 mS cm −1 ) as well as electrochemical stability, offers a very good electrolyte−electrode interface, reduces ohmic polarization, and increases reaction kinetics during device operation.…”

“…Fundamentally, retarded kinetics during the crystal growth in the presence of precise surface deactivators helps in the growth of crystallites with tuned dimension and systematic arrangement, which essentially leads to materials with lower surface energy and higher microstructural uniformity. , Further, it should be noted that all-solid-state (electrode, electrolyte, and separator) devices enjoy prominent advantages such as ease of storage and transportability, no loss in cyclic efficiency, and high-potential tolerance of the solid components over the devices where liquid-phase materials are used as one or more of the components. , In the context of electrolytes in all-solid-state electrochemical energy storage devices, gel polymer electrolytes play a vital role, as they simultaneously function as electrolytes, separators, and binders . Among various gel polymer electrolytes, polyvinyl alcohol (PVA)–KOH is most widely utilized in all-solid-state devices, where a basic electrolyte medium is the prime requirement . This is because the PVA–KOH gel electrolyte can operate in a wide range of pHs, just like the aqueous electrolyte solutions, is not corroding for the electrode materials, serves as a mechanically strong elastic coating, possesses good affinity to hold the solvents, and can operate in a wider temperature window.…”

Hierarchically Uniform 2D Porous Sheet-like NiO/NiCo2O4: A High-Performance Positrode Material for All-Solid-State Hybrid Pseudocapacitors with Superior Ragone and Cyclic Efficiencies

“…27 Contextually, poly(vinyl alcohol)-KOH solidgel electrolyte is most commonly used because (i) it can operate in a broad pH range, (ii) it is noncorrosive to the electrodes, (iii) it acts as a durable elastic coating, (iv) it has good affinity to hold the aqueous solvent, (v) it can operate in a wide range of temperatures, (vi) it has excellent room temperature ionic conductivity as well as electrochemical stability, and (vii) it offers rich electrode−electrolyte interface for low resistance during the device operation. 11,12,23,28,29 In the overall context, herein, we report a simplistic and kinetically controlled crystal growth strategy to design highly uniform 2D porous sheet-like microstructure of NiO/NiCo 2 O 4 with high surface area and rich pore architecture. Furthermore, the NiO/NiCo 2 O 4 has been subjected to thorough physicoelectrochemical evaluation to ascertain that it can be an exceptional positrode material to fabricate high Ragone efficient all-solid-state asymmetric pseudocapacitors with outstanding cyclic durability.…”

“…Furthermore, all-solid-state (electrode, electrolyte, and separator are all in solid states) architectures of the electrochemical energy storage devices possess significant advantages in the context of storage and transportability, mechanical stress tolerance, and potential integration in real electronic architectures. , Among various solid electrolytes in supercapacitors, gel polymer electrolytes are distinctive as they simultaneously act as electrolytes, binders, and separators in the devices . Contextually, poly­(vinyl alcohol)-KOH solid-gel electrolyte is most commonly used because (i) it can operate in a broad pH range, (ii) it is noncorrosive to the electrodes, (iii) it acts as a durable elastic coating, (iv) it has good affinity to hold the aqueous solvent, (v) it can operate in a wide range of temperatures, (vi) it has excellent room temperature ionic conductivity as well as electrochemical stability, and (vii) it offers rich electrode–electrolyte interface for low resistance during the device operation. ,,,, …”

Construction of shrimp shell (SS) waste-based carbon electrode-gel polymer electrolyte (GPE) system for flexible symmetric supercapacitors

“…29 GPE based on synthetic polymers such as PVA, PEO, and polyacrylamide has been extensively studied, but the development of renewable natural polymer-based GPE has a stronger appeal for sustainable development. [30][31][32] SS-derived chitosan is a natural polymer with good renewable properties, structural strength, and toughness and could be used in the GPE. However, the H atoms in chitosan polymers are tightly bound, resulting in very poor electrical conductivity of chitosan in the pure state of matter (∼10 −8 S cm −1 ), making it unsuitable for direct use in electrolyte materials.…”