Gel Electrolyte Research Articles

MnO2‐Infused PAN Carbon Nanofibers Synthesized via Electrospinning for Enhanced Supercapacitor Performance

AbstractSupercapacitors (SCs) are crucial for high‐performance energy storage, offering high power density, swift charge–discharge rates, and durability. The enhancement of their performance hinges on the development of advanced electrode materials. This study presents an innovative method involving polyacrylonitrile (PAN) nanofibers adorned with manganese dioxide (MnO₂) nanoparticles (NPs), created through electrospinning and subsequent thermal treatment. This synergy exploits the extensive surface area and electrical conductivity of PAN nanofibers along with the substantial capacitance of MnO₂. The MnO₂‐coated PAN nanofibers reached an impressive specific capacitance of 247 F g−1 at a scan rate of 10 mVs−1, markedly boosting the efficacy of all‐solid‐state asymmetric SCs. The SCs, incorporating a polyvinyl alcohol (PVA)/potassium hydroxide (KOH) gel electrolyte, exhibited an energy density of 8.2 Wh kg−1 at a power density of 700 W kg−1, preserving 80.4% of their original capacitance after 5000 cycles. This research is pioneering in combining MnO₂ with PAN nanofibers, marking a significant leap forward in supercapacitor technology with enhanced energy storage capacity and prolonged stability. These findings underscore the promise of these composite materials in future energy storage solutions.

Attaining promising efficiency through a Quasi-Solid-State symmetrical supercapacitor and Dye-Sensitized solar cell counter electrode utilizing bifunctional Nitrogen-Doped microporous activated carbon

This study addresses the imperative need for high-performance and sustainable energy storage and conversion technologies by leveraging the unique properties of nitrogen-doped porous carbon (N@WnAC) derived from the waste walnut shells (WnS). In the realm of supercapacitors, the N@WnAC demonstrates remarkable performance in a three-electrode system, showcasing a high specific capacitance value of 276.7 Fg−1 at 1 Ag−1, outstanding stability (96.6 %, 5000 charge–discharge cycles) and favourable rate capability (68.8 % at 10 Ag−1). Moreover, a quasi-solid-state symmetrical supercapacitor (N@WnAC//N@WnAC) is fabricated with PVA/H2SO4 gel electrolyte, underscores outstanding performance by delivering high capacitance (126.2 Fg−1 at 0.5 Ag−1), promising rate capability (71.8 % at 5 Ag−1), favourable long-term stability (93.3 %, 5000 charge–discharge cycles), and faster charge–discharge kinetics compared to conventional counterparts. At the same time, N@WnAC//N@WnAC delivers a high energy density (42.27 Whkg−1 at 0.5 Ag−1) that was retained up to 23.96 Whkg−1 even at 5 Ag−1. Simultaneously, the study explores the potential of N@WnAC as a counter-electrode (CE) in dye-sensitized solar cells (DSSC). The obtained results underscore that unique nitrogen doping enhances the electrocatalytic activity, leading to improved electron transfer kinetics and overall cell performance. Moreover, the N@WnAC CE-based DSSC delivers a promising overall solar-to-electrical conversion efficiency of 5.84 %.

Enhancing photovoltaic cell design with multilayer sequential neural networks: A study on neodymium-doped ZnO nanoparticles

Multilayer sequential neural networks, a powerful machine learning model, demonstrate the ability to learn intricate relationships between input features and desired outputs. This study focuses on employing such models to design photovoltaic cells. Specifically, neodymium (Nd)-doped ZnO nanoparticles (NPs) were utilized as a photoanode for fabricating dye-sensitized solar cells (DSSCs). A natural dye extracted from Spinacia oleracea was employed, while two types of electrolytes, liquid and gel (polyethylene glycol-based), were used for comparative analysis. Extensive material characterization of the photoanode highlights the impact of Nd content on the physicochemical properties of ZnO. Notably, when the doped photoanode and gel electrolyte were combined, a substantial 110% improvement in power conversion efficiency (PCE) was achieved. Building on these findings, the machine learning model in this research accurately predicts the current-voltage (I-V) curve values for such photoanodes, with an impressive accuracy of 98%. Additionally, the model illuminates the significance of variables like crystal distortion, texture coefficient, and doping concentration, underscoring their importance in the context of photovoltaic cell design.

Loofah-based self-powered triboelectric nanogenerator-supercapacitor for an integrated self-charging energy system

New urbanization is ushering in a surge in construction and amplifying a substantial demand for urban road development, simultaneously spurring innovation and development of environmentally sustainable power sources. Triboelectric nanogenerator (TENG), a revolutionary technology of energy conversion, efficiently capturing high-entropy energy from the environment and offering the advantages of self-powered and immediacy. Recognizing the critical need to store the energy harvested by TENGs, we present an integrated energy conversion and storage system that combines a loofah-based self-powered rotating TENG (LS-TENG) with a supercapacitor. The maximum instantaneous output power and the corresponding instantaneous power density of the LS-TENG are 0.75mW and 202.69mW/m2 at 30rpm. The supercapacitor, featuring carbon nanotube (CNT) interdigitated electrodes created through microelectronic printing technology, utilizes polyacrylamide (PAM)-lithium chloride (LiCl) as a gel electrolyte (adhesion strength of 16.69 kPa). The supercapacitor is seamlessly integrated onto the back of the LS-TENG’s stator, which effectively simplified the energy conversion and storage system. At a current density of 0.01mA/cm2, the supercapacitor achieves a high volumetric capacitance of 341.47 mF/cm3, an energy density of 17.07mWh/cm3, and a power density of 257.07 mW/cm3, with a remarkable capacitance retention rate of 99.12% after 30000 cycles at a current density of 0.02mA/cm2. Furthermore, a concept demonstration of an integrated self-charging energy system is implemented, in which the supercapacitor can be charged at wind speed rate of 3.0m/s. The proposed integrated energy storage and conversion system makes it ideal for converting and storing wind energy.

A LiPF6 gel-polymer electrolyte for a solid-state supercapacitor with polyaniline/MnCo layered double hydroxide nanosheets as active electrode material

This paper introduces a novel solid-state electrolyte for supercapacitors (SCs), employing a LiPF6 gel polymer coupled with innovative electrodes composed of MnCo-layered double hydroxide (LDH) nanosheets. The newly synthesized LiPF6 gel polymer electrolyte exhibits superior ionic conductivity and mechanical flexibility, making it an ideal candidate for advanced energy storage devices that require bending and twisting capabilities. The thermal analyses and morphological characterizations were evaluated using DSC, XRD, FT-IR, BET, TEM and FE-SEM techniques. The MnCo-LDH nanosheets, synthesized via a facile co-precipitation method, served as the electrode material. It was expected that the collaborative interaction between the LiPF6 polymer matrix and the multifaceted nanoflower-shaped MnCo-LDH nanosheets could improve electron mobility and supply an increased surface area for redox processes. Electrochemical analyses, including cyclic voltammetry and galvanostatic charge-discharge tests, reveal a marked improvement in the specific capacitance, rate capability, and cyclic stability of the assembled SCs. This novel electrolyte-electrode configuration yielded a specific capacity of up to 198.66 F g−1 at 1.6 A g−1 and exhibited rate performance with retention of 89.15 % at an elevated current density of 10 A g−1 for 2-Hydroxyehtyl cellulose: LiPF6 gel polymer with molar ratio of 1: 2. Moreover, it demonstrates enduring cyclic stability with no capacity decay after 10,000 cycles. We delineated the pivotal role of Mn in facilitating electron transfer kinetics and moderating interactions with Co ions. The introduction of strain within the LDH structure promulgates a conducive environment for electrochemical reactions.

Novel Integrated Reference-Counter Electrode for Electrochemical Measurements of HOMO and LUMO Levels in Small-Molecule Thin-Film Semiconductors for OLEDs

Organic light-emitting diodes (OLEDs) are a prominent display technology, yet the accurate characterization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels in their constituent materials remains challenging. This study introduces a novel integrated reference-counter electrode (IRCE) assembly, leveraging a gel polymer electrolyte with an embedded silver quasi-reference electrode, facilitating the electrochemical measurement of HOMO and LUMO levels in small molecular thin-film semiconductors. Calibration of the IRCE against ferrocene enables the establishment of an absolute energy scale. Comparative stability tests against a standard Ag/AgNO3 reference electrode confirm the IRCE's reliability. Electrochemical characterization using cyclic voltammetry was performed on prototypical OLED materials, including NPB, TCTA, PO-T2T neat films, and an NPB:PO-T2T exciplex film. While NPB and PO-T2T exhibited stable voltammograms, TCTA showed signs of electropolymerization. Additionally, the HOMO level of the NPB:PO-T2T exciplex was slightly shifted compared to that of NPB, suggesting interactions within the exciplex. The results demonstrated the IRCE's capability to accurately determine frontier energy levels in thin films, paving the way for better device modeling and a better understanding of underlying electronic processes in organic semiconductors.

Nitrogen-doped graphene quantum dot embedded polyaniline for the fabrication of high-performance flexible supercapacitor with enhanced cycling stability

This article explains the synthesis of high surface area nitrogen-doped graphene quantum dots embedded polyaniline (PANI) and its effectiveness in fabricating flexible printed supercapacitors. A noticeable change in polyaniline's morphology and specific surface area suggests the successful incorporation of graphene quantum dots into the polymer matrix. The synergistic interaction of polyaniline with graphene quantum dots is evident in its energy storage performance. The fabricated supercapacitor prototype with PVA/HCl gel electrolyte exhibited a very high areal capacitance of 128.01 mF cm−2, with an areal energy density of 11.40 μWh cm−2, and a power density of 640 μW cm−2 at 1.6 mA cm−2 current density. Most importantly, the developed supercapacitor exhibited 76.70% of original capacitance after 5000 galvanostatic charge-discharge cycles, which was found to be far better result than a supercapacitor fabricated with pristine polyaniline. Furthermore, the developed supercapacitor demonstrated excellent mechanical stability, retaining its performance at diverse angles and even after 4000 bending cycles. These characteristics make PANI/N-GQD-based supercapacitors appropriate for wearable devices requiring flexibility, cycling stability, and mechanical toughness.

Recycling of spent heat pack towards Fe-Fe3O4@NC based cathode for electrocatalytic ORR in direct methanol fuel cells and Al-air batteries

The effective repurposing of waste materials is crucial for sustainable development. The widespread use of disposable iron-based chemical warmers (IBCW) generates substantial solid waste annually. In this study, IBCWs were repurposed as raw materials to synthesize different electrocatalyst composites comprising metallic and oxide forms of iron embedded in nitrogen-doped carbon (NC). The composites were evaluated as oxygen reduction reaction (ORR) catalysts. The optimized Fe-Fe3O4@NC demonstrated enhanced ORR kinetics, with an onset potential of 0.92 V and a half-wave potential of 0.86 V vs. RHE. As an air cathode, Fe-Fe3O4@NC achieved a power density of 33.3 mW cm−2 at 88 mA cm−2, demonstrating its practical applicability. Additionally, a quasi solid-state aluminium-air battery (SAAB) was assembled using this catalyst as the air cathode with a PVA-KOH gel electrolyte as the separator. The quasi SAAB exhibited an open circuit voltage (OCV) of 1.46 V, a power density of 40 mW cm-2, and good rate capability compared to Pt/C. The combined effect of metallic and oxide iron with nitrogen doping enhances the overall catalytic activity. This study demonstrates that IBCWs can be effectively transformed into valuable catalysts for renewable energy applications, enabling clean and sustainable utilization of waste materials.

Self‐Healing Waterborne Polyurethanes as a Sustainable Gel Electrolyte for Flexible Electrochromic Devices

Self‐Healing Waterborne Polyurethanes as a Sustainable Gel Electrolyte for Flexible Electrochromic Devices

Supramolecular polymer cross-linking gel electrolyte for highly stable quasi-solid-state lithium metal batteries

Lithium (Li) metal batteries have the advantage of high energy density, but the Li dendrites risk piercing the separator and causing a short circuit in the battery. Replacing the liquid electrolytes with gel electrolytes is considered an effective strategy to solve the issues. Herein, a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel electrolyte, improved with multifunctional supramolecular polymer (MSP), was prepared to enhance the cycling stability and energy density of quasi-solid-state Li metal batteries. The MSP addictive constructs a cross-linked network structure with PVDF-HFP matrix and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) through hydrogen bonding, improving the mechanical strength of the composite gel electrolyte (PH-10%MSP-GE) to against the growth of Li dendrites. Moreover, the pre-lithiated sulfonic acid groups, conductive polyether groups of MSP, and the attraction of TFSI– anions, promote the Li-ion transportation of the composite gel electrolyte. Finally, the Li||Li symmetric cell cycle stably for over 450 h. The Li||LiFePO4 full cell demonstrates a high energy density and excellent cycling stability for over 600 cycles, with a capacity retention rate of up to 98.7%. This work provides valuable insights into the preparation of multifunctional composite gel polymer electrolytes and competitive quasi-solid-state Li metal batteries.

Revolutionizing fiber batteries with polymer gel electrolyte: a groundbreaking innovation in wearable energy

Revolutionizing fiber batteries with polymer gel electrolyte: a groundbreaking innovation in wearable energy

Modulating the internal porosity of organogel electrolyte via pore-forming agent for low temperature resistant and flexible quasi-solid supercapacitors

The widely applicable gel polymer electrolytes (GPEs) hold significant promise for the commercialization of low-temperature flexible quasi-solid-state supercapacitors (FQSCs). However, their flexibility and electrochemical performance are compromised under extreme cold conditions, severely limiting their practical applications. Inspired by the novel effects of “pore-form agents (PFA)”in hydrogel-controlled drug release & delivery, polyvinyl alcohol (PVA) hydrogel electrolytes with optimized internal porosity (polymeric structure) were prepared by introducing PFA as pore-regulator and in-situ leaching process, hereby enhancing the hydrogel's electrical conductivity and low-temperature performance. Furthermore, in order to further enhance its low-temperature tolerance, the composition of the electrolyte was adjusted via binary solvent replacement method. FQSCs composed of PVA-PFA30-EG exhibited significantly improved high specific capacitances of 131.72 F g−1 at 25 °C and 72.90 F g−1 at −40 °C when tested at 1 A g−1, with only a 6.36 % capacitance decay after 10,000 cycles at −40 °C. This performance surpasses that of most previously reported low-temperature FQSCs. The novel approach proposed in this paper provides a new avenue for flexible energy storage devices in extremely cold conditions.

Molecule-Level Multiscale Design of Nonflammable Gel Polymer Electrolyte to Build Stable SEI/CEI for Lithium Metal Battery

HighlightsNonflammable gel polymer electrolyte (SGPE) is developed by in situ polymerizing trifluoroethyl methacrylate (TFMA) monomers with flame-retardant triethyl phosphate (TEP) solvents and LiTFSI–LiDFOB dual lithium salts.Molecular polarity interaction between TEP and PTFMA mitigates interfacial reactions and changes the solvation of Li+.SGPE forms stable inorganic-rich solid electrolyte interface/cathode electrolyte interface layer, exhibiting well compatibility with Li anode and LiCoO2-type high-voltage cathode.

A 3D network-structured gel polymer electrolyte with soluble starch for enhanced quasi-solid-state lithium-sulfur batteries

The polysulfide shuttling effect and safety concerns associated with liquid electrolytes impede the commercialization of lithium-sulfur (Li-S) batteries. We report a novel gel polymer electrolyte (GPE) denoted as "PTPHS" prepared via facile ultraviolet polymerization of pentaerythritol tetrakis (3-mercaptopropionate) (PETT) and pentaerythritol tetraacrylate (PETEA) with poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the polymer matrix. Soluble starch (SST) is incorporated as an interacting filler to construct a 3D network structure with intermolecular hydrogen bonds. This unique architecture not only ensures high ionic conductivity and mechanical robustness but also effectively mitigates the polysulfide shuttling effect, thereby improving cycling stability. The PTPHS-based Li-S cell exhibits stable cycling over 150 cycles at 0.2 C with 87.6 % capacity retention. This strategy provides insights into material development and structural design of GPEs for high-performance quasi-solid-state Li-S batteries.

Introducing phosphoric acid to fluorinated polyimide towards high performance laser induced graphene electrodes for high energy micro-supercapacitors

Micro-supercapacitors (MSCs) have wide application prospects in microelectronic fields such as wearable electronics due to merits of stable performance, high safety and easy integration. However, the relatively low energy density of MSCs limits their practical application. In this context, phosphorus and fluorine co-doped laser-induced graphene (FP-LIG) microelectrodes were fabricated from fluorinated polyimide containing phosphoric acid by laser direct writing (LDW) method. The introduced phosphoric acid slows down the decomposition of –CF3 during the LDW process, resulting in much more ordered and stable pores; meanwhile, phosphorus entered the graphene lattice to replace some carbon atoms, forming a C3PO structure, which not only stabilizes the interface between the electrode and the electrolyte and therefore achieves an enlarged working potential of 1.4 V, but also increases the wettability of the electrode. Using FP-3-LIG microelectrodes and PVA/H2SO4 as the gel electrolyte, the assembled FP-3-MSC demonstrates significantly enhanced energy density, delivering an energy density of 10.40 μWh cm−2 (@0.09 mA cm−2), 2.7 times that of F-MSC and 346.7 times that of MSC. FP-3-MSC has excellent cyclic stability, displaying an areal capacitance retention rate of above 90 % after 10,000 long cycles. In addition, FP-3-MSC demonstrates excellent flexibility, indicating promising potential in the field of flexible wearable electronics.

Dipole Moment Dictates the Preferential Immobilization in Gel Electrolytes for Ah-level Aqueous Zinc-Metal Batteries.

Aqueous Zn-metal batteries are of great interest due to their high material abundance, low production cost, and excellent safety. However, they suffer from severe side reactions and notorious dendrite growth closely related to electrolytes. Here, in-situ generated zwitterionic polymers are used as gel electrolytes to overcome these problems. It is shown that anions and H2O, but not anions and cations, are preferentially immobilized at different sites of zwitterionic polymers, facilitating the free migration of Zn2+ and reducing the side reactions. This immobilization can be associated with the dipole moment of zwitterionic polymers. As a result, poly[3-dimethyl(methacryloyl oxyethyl) ammonium propane sulfonate] (PDMAPS) stands out from a series of zwitterionic polymers and outperforms the other candidates in electrochemical performance. The symmetric cells using PDMAPS smoothly operate ~9000 h at 0.5 mA cm-2 for 0.5 mAh cm-2, much better than the controls. Moreover, PDMAPS enables an Ah-level pouch cell for continuous cycling. These results not only benefit the rational molecular design of advanced electrolytes, but also demonstrate the promising potential of zwitterionic polymers in aqueous Zn-metal batteries.

Development study of proton conductor: poly(vinyl alcohol)-based gel electrolyte for energy storage devices

Development study of proton conductor: poly(vinyl alcohol)-based gel electrolyte for energy storage devices

Carboxymethyl Cellulose Gel Electrolyte Based on Hydrolyzed Keratin Modified for Dendrite-Free Zinc-Ion Batteries.

In order to alleviate the dendrite problem of zinc-ion batteries, a gel electrolyte is prepared by Maillard reactions occurring between hydrolyzed wool keratin and carboxymethyl cellulose under heating conditions. The prepared gel electrolyte with the addition of hydrolyzed wool keratin possesses good mechanical properties, and its maximum breaking strength, Young's modulus, and elastic modulus are 58.7, 10.77 MPa, and 157.73 MJ m2, respectively, which are far superior to those of the pure carboxymethyl cellulose gel electrolyte. Because hydrolyzed wool keratin includes amino acids and polypeptides, the ionic conductivity of the prepared gel electrolyte is improved. More importantly, amino and carboxyl groups introduced by hydrolyzed wool keratin contribute to uniform deposition of zinc ions and ease dendrite growth. The assembled symmetric battery was stable for 600 h at a current density of 0.5 mA cm-2 with a capacity of 0.5 mAh cm-2. Combined with a NH4V4O10 cathode, a full battery provides a cycling stability of over 2000 h with a Coulomb efficiency of 98.02%.

Soy protein isolate–based gel polymer electrolyte for flexible solid-state supercapacitor

At present, the polymer matrices of most polymer electrolytes are derived from petroleum-based synthetic polymers. Herein, sustainable and renewable soy protein isolate (SPI) was grafted with methacrylic acid (MAA) and then cross-linked by ring-opening reaction with polyethylene glycol diglycidyl ether as cross-linking agent to obtain a biomass-based polymer electrolyte. Results show that when the added amount of MAA is twice the quality of SPI, gel polymer electrolyte displays the best comprehensive properties and presents the highest ionic conductivity of 5.24 × 10−3 S/cm. The flexible supercapacitor was fabricated by using SPI-based gel polymer electrolyte with activated carbon electrodes, which exhibited excellent specific capacitance (128.63 F/g) and energy density (9.52 Wh/kg) at 0.5 A/g with a decent capacitance retention of 93% after 5000 charge–discharge cycles. It can be ascribed that grafting modification of SPI improves the interface performance of electrode–polymer electrolyte. Furthermore, potassium iodide is introduced to form a redox polymer electrolyte to achieve a high-energy-density supercapacitor, which provides outstanding energy density of 24.40 Wh/kg at 1.0 A/g. This work demonstrates that sustainable and renewable biomass can be converted into matrix of polymer electrolyte for high performance supercapacitor based on aqueous polymer electrolyte.

Impact of Introducing EMIM-BF4 as Ionic Liquid Solvent on Electrochemical Properties of PVdF–HFP Based Sodium Ion Conducting Gel Polymer Electrolytes

Impact of Introducing EMIM-BF4 as Ionic Liquid Solvent on Electrochemical Properties of PVdF–HFP Based Sodium Ion Conducting Gel Polymer Electrolytes