Conductive Poly Research Articles

Structural Restoration of Degraded LiFePO 4 Cathode with Enhanced Kinetics Using Residual Lithium in Spent Graphite Anodes

Structural Restoration of Degraded LiFePO ₄ Cathode with Enhanced Kinetics Using Residual Lithium in Spent Graphite Anodes

Superior, Environmentally Tolerant, Flexible, and Adhesive Poly(ionic liquid) Gel as a Multifaceted Underwater Sensor.

In recent years, gel-based sensors have been widely considered and fully developed. However, it is of vital importance, yet rather challenging to achieve a multifaceted gel, which can unify the advantages of favorable conductivity, high adhesion, excellent environmental resistance, and so forth and be applied in various harsh conditions. Herein, an ideal, extremely stable, adhesive, conductive poly(ionic liquid) gel (PILG) was designed via a one-step photoinitiated radical polymerization based on 1-vinyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide (VBIm-NTf2) cross-linked with ethylene glycol dimethacrylate (EGDMA) in methyltributylammonium bis(trifluoromethanesulfonyl)imide (N1444-NTf2) medium. There are abundant hydrophobic butyl chains and fluorinated groups in VBIm-NTf2 and N1444-NTf2, which can impart the PILG with stable conductivity, excellent environmental tolerance, and adhesion even in water due to the ion-dipole and ion-ion interactions. The resulting PILG can be assembled as a soft and smart sensor that can be applied in specific conditions such as underwater or undersea and even in dynamic water, achieving a stable signal transmission. Meanwhile, the PILG can be utilized as a flexible electrode to convey ECG signals in air or water whether it is in the static or dynamic state. Therefore, it is envisioned that this novel PILG will serve as a hopeful electrical device for signal detection and healthy management in specific environments.

Immuno-affinity Potent Strip with Pre-Embedded Intermixed PEDOT:PSS Conductive Polymers and Graphene Nanosheets for Bio-Ready Electrochemical Biosensing of Central Nervous System Injury Biomarkers.

Future point-of-care (PoC) and wearable electrochemical biosensors explore new technology solutions to eliminate the need for multistep electrode modification and functionalization, overcome the limited reproducibility, and automate the sensing steps. In this work, a new screen-printed immuno-biosensor strip is engineered and characterized using a hybrid graphene nanosheet intermixed with the conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymers, all embedded within the base carbon matrix (GiPEC) of the screen-printing ink. This intermixed nanocomposite ink is chemically designed for self-containing the "carboxyl" functional groups as the most specific chemical moiety for protein immobilization on the electrodes. The GiPEC ink enables capturing the target antibodies on the electrode without any need for extra surface preparation. As a proof of concept, the performance of the non-functionalized ready-to-immobilize strips was assessed for the detection of glial fibrillary acidic protein (GFAP) as a known central nervous system injury blood biomarker. This immuno-biosensor exhibits the limit of detection of 281.7 fg mL-1 (3 signal-to-noise ratio) and the sensitivity of 322.6 Ω mL pg-1 mm-2 within the clinically relevant linear detection range from 1 pg mL-1 to 10 ng mL-1. To showcase its potential PoC application, the bio-ready strip is embedded inside a capillary microfluidic device and automates electrochemical quantification of GFAP spiked in phosphate-buffered saline and the human serum. This new electrochemical biosensing platform can be further adapted for the detection of various protein biomarkers with the application in realizing on-chip immunoassays.

Multifunctional polymeric surface coatings of carbon fibre electrodes for enhanced energy storage performance

We report a proof-of-concept study on the development of multifunctional surface coatings for carbon fibre (CF) electrodes in structural energy composites, which for the first time addresses three key properties of CF: capacitance, tensile properties and interfacial adhesion, simultaneously. Multifunctional coatings have been designed by covalently grafting conductive and redox active poly(o-phenylenediamine) (PoPD) on CF via surface electro-initiated polymerisation using different diazonium salts. This has resulted in improvements in specific capacitance, tensile strength, tensile modulus and interfacial shear strength (IFSS) up to 30 F g−1, 4.58 GPa, 276 GPa and 43.5 MPa, respectively, all of which are higher than the values reported for pristine CF. To further improve the IFSS, a bilayered polymeric coating has been designed by electro-grafting polyacrylamide on top of the conductive PoPD layer, which led to specific capacitance, tensile strength, tensile modulus and IFSS (up to 9 F g−1, 4.28 GPa, 256 GPa and 55.6 MPa, respectively). The non-conductive polyacrylamide layer on top of the PoPD layer is thought to be the reason for depressed capacitive performance, though this does come at a trade-off for improved fibre–matrix adhesion. Thus, a means to tailor this material based on end user priorities is presented herein. In contrast to the conventional methods of surface activation for improving the capacitance of CF, which often result in a trade-off between electrochemical and mechanical/interfacial properties of CF, this method offers a means to simultaneously enhance the electrochemical, mechanical, and interfacial performance of CF with great tunability.

Muscle-Mimetic Highly Tough, Conductive, and Stretchable Poly(ionic liquid) Liquid Crystalline Ionogels with Ultrafast Self-Healing, Super Adhesive, and Remarkable Shape Memory Properties.

Here, we report a simple method for preparing muscle-mimetic highly tough, conductive, and stretchable liquid crystalline ionogels which contains only one poly(ionic liquid) (PIL) in an ionic liquid via in situ free radical photohomopolymerization by using nitrogen gas instead of air atmosphere. Due to eliminating the inhibition caused by dissolved oxygen, the polymerization under nitrogen gas has much higher molecular weight, lower critical sol-gel concentration, and stronger mechanical properties. More importantly, benefiting from the unique loofah-like microstructures along with the strong internal ionic interactions, entanglements of long PIL chains and liquid crystalline domains, the ionogels show special optical anisotropic, superstretchability (>8000%), high fracture strength (up to 16.52 MPa), high toughness (up to 39.22 MJ/m3), and have ultrafast self-healing, ultrastrong adhesive, and excellent shape memory properties. Due to its excellent stretchability and good conductive-strain responsiveness, the as-prepared ionogel can be easily applied for high-performance flexible and wearable sensors for motion detecting. Therefore, this paper provides an effective route and developed method to generate highly stretchable conductive liquid crystalline ionogels/elastomers that can be used in widespread flexible and wearable electronics.

Modulating the Band Structure of Metal Coordinated Salen COFs and an In Situ Constructed Charge Transfer Heterostructure for Electrocatalysis Hydrogen Evolution.

A series of crystalline, stable Metal (Metal = Zn, Cu, Ni, Co, Fe, and Mn)‐Salen covalent organic framework (COF)EDA complex are prepared to continuously tune the band structure of Metal‐Salen COFEDA, with the purpose of optimizing the free energy intermediate species during the hydrogen evolution reaction (HER) process. The conductive macromolecular poly(3,4‐ethylenedioxythiophene) (PEDOT) is subsequently integrated into the one‐dimensional (1D) channel arrays of Metal‐Salen COFEDA to form heterostructure PEDOT@Metal‐Salen COFEDA via the in situ solid‐state polymerization method. Among the Metal‐Salen COFEDA and PEDOT@Metal‐Salen COFEDA complexes, the optimized PEDOT@Mn‐Salen COFEDA displays prominent electrochemical activity with an overpotential of 150 mV and a Tafel slope of 43 mV dec−1. The experimental results and density of states data show that the continuous energy band structure modulation in Metal‐Salen COFEDA has the ability to make the metal d‐orbital interact better with the s‐orbital of H, which is conducive to electron transport in the HER process. Moreover, the calculated charge density difference indicates that the heterostructures composed of PEDOT and Metal‐Salen COFEDA induce an intramolecular charge transfer and construct highly active interfacial sites.

Effects of different mixing methods on the conductivities of poly(2-ethyl aniline)/graphene and poly(2-ethyl aniline)/expanded graphite composites

In this study, the preparation of poly(2-ethyl aniline) (PEAn)/Graphene and PEAn/Expanded Graphite (EG) composites using different mixing methods and the effect of the preparation conditions of composites on their electrical conductivities were investigated. Herein, it was examined both the effect of the sonication time of EG and Graphene in HCl medium before the polymerization on their homogeneous dispersion in the PEAn matrix and the effect of the three different mixing methods, including magnetic stirring, ultrasonication, and ball milling, on the formation of network in the composites. From the morphological characterization obtained by SEM, due to π-π* electron interaction, 2-EAn molecules were polymerized on the surface of graphene and EG. It was determined that the composite with the highest conductivity was obtained by in situ polymerization of 2-EAn in the presence of graphene via a ball milling method for 10 h, after the sonication of graphene in aqueous HCl medium for 6 h. The conductivity of this PEAn/Graphene (1:1 by weight) composite increased from 3.5x10−7 Scm−1 to 1.57 Scm−1 compared to pure PEAn.

Electrospun poly(ionic liquid) nanofiber separators with high lithium-ion transference number for safe ionic-liquid-based lithium batteries in wide temperature range

Ionic-liquid electrolytes (ILEs) promise high-safety lithium-metal batteries (LMBs) because of their wide electrochemical stability window and nonflammability. However, existing commercial polyolefin separators for LMBs are incompatible with ILEs owing to poor wettability and thermal stability. Also, conventional ILE/separator systems suffer from the inherent sluggish Li+ transport kinetics. Here we report on a novel highly Li+-conductive poly(ionic liquid) nanofiber membrane (PILNM) separator. It exhibits nonflammability, excellent thermal stability, and remarkable wettability with ILEs, achieving high ionic conductivity (3.81 mS cm−1) and significantly improved Li+ transference number (0.47). Benefiting from desirable interactions between the charged PILNM and ions of the ILE, the first solvation shell of [lithium-bis(trifluoromethane)sulfonimidex]1−x ([Li-TFSIx]1−x) complex is regulated. Fast Li+ transport and dendrite-free lithium metal anode are achieved. The PILNM combined with the ILE enables Li||LiFePO4 cells with enhanced capacities and rate capability in a wide temperature range from 25 °C to 120 °C. Notably, the thermal safety of Li|PILNM/ILE|LiFePO4 pouch cells at elevated temperatures has been further verified by adiabatic accelerating rate calorimetry. This work provides a new strategy to design and fabricate functionalized, thermally durable separators towards high-safety ILE-based LMBs.

Conductive and transparent poly (N-isopropylacrylamide) hydrogels with tunable LCST copolymerized by the green acrylamide-based deep eutectic solvent

Smart hydrogels have been widely applied in the bionic intelligent devices for the virtues of biocompatibility, well processibility, environmental sensitivity, and so on. Traditional poly(N-isopropylacrylamide) (PNIPAM) hydrogel has the native response to the temperature change, but the weak strength and narrow phase transition point have limited its applications. Moreover, the poor conductivity of PNIPAM has shields the response signals to the outside. In this work, we have put forward a facile strategy by introducing the ionic conductive deep eutectic solvent (DES) composed of acetylcholine chloride (ACh) and acrylamide (AAm). Followed by one-step copolymerization of AAm and NIPAM, the PAAm-DES/PNIPAM hydrogel formed with the tunable lowest critical solution temperature (LCST), high strength, fine transparence, and good conductivity. As a result, the hydrogel showed the high-sensitive, wide-range and stable response on the outer strain and thermal change, which can play as a sensing element in the intelligent devices. This cost-effective method will be a potential way for fabricating the environmental and multifunctional materials.

Construction of Bio-inspired Film with Engineered Hydrophobicity to Boost Interfacial Reaction Kinetics of Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries typically suffer from sluggish interfacial reaction kinetics and drastic cathode dissolution owing to the desolvation process of hydrated Zn2+ and continual adsorption/desorption behavior of water molecules, respectively. To address these obstacles, a bio-inspired approach, which exploits the moderate metabolic energy of cell systems and the amphiphilic nature of plasma membranes, is employed to construct a bio-inspired hydrophobic conductive poly(3,4-ethylenedioxythiophene) film decorating α-MnO2 cathode. Like plasma membranes, the bio-inspired film can "selectively" boost Zn2+ migration with a lower energy barrier and maintain the integrity of the entire cathode. Electrochemical reaction kinetics analysis and theoretical calculations reveal that the bio-inspired film can significantly improve the electrical conductivity of the electrode, endow the cathode-electrolyte interface with engineered hydrophobicity, and enhance the desolvation behavior of hydrated Zn2+ . This results in an enhanced ion diffusion rate and minimized cathode dissolution, thereby boosting the overall interfacial reaction kinetics and cathode stability. Owing to these intriguing merits, the composite cathode can demonstrate remarkable cycling stability and rate performance in comparison with the pristine MnO2 cathode. Based on the bio-inspired design philosophy, this work can provide a novel insight for future research on promoting the interfacial reaction kinetics and electrode stability for various battery systems.

Mechanically robust and conductive poly(acrylamide) nanocomposite hydrogel by the synergistic effect of vinyl hybrid silica nanoparticle and polypyrrole for human motion sensing

Mechanically robust and conductive poly(acrylamide) nanocomposite hydrogel by the synergistic effect of vinyl hybrid silica nanoparticle and polypyrrole for human motion sensing

Fabrication of conductive and superhydrophobic poly(lactic acid) nonwoven fabric for human motion detection

AbstractIn recent years, piezoresistive pressure sensors with superhydrophobicity have aroused considerable attention. In addition, to comply with “sustainable development” strategy, the sensors fabricated with eco‐friendly materials is of great theoretical and practical significance. Herein, tannic acid (TA) was first absorbed on the surface of poly(lactic acid) (PLA) nonwoven fabric by simple dipping method. After that, silver (Ag) particles were in situ generated on the surface to construct roughness with the reduction role of TA by immersing the fabric into silver nitrate aqueous solution. Finally, n‐lauryl mercaptan was grafted on the Ag particles via Ag–S bonds to provide low surface energy, and a conductive and superhydrophobic PLA (CSPLA) nonwoven fabric was fabricated. The obtained CSPLA nonwoven fabric had a high water contact angle of 150.3°. The fabric‐based piezoresistive pressure sensor possessed high sensitivity, fast response, good stability, and excellent reusability, and was successfully applied for detecting various human motions including voice recognition, joint bending, stomping, walking, and jumping. The fabricated sensor has great application potential in the fields of touchable displays, electronic skins, intelligent robotics, and wearable devices.

Flexible and thermal conductive poly (vinylidene fluoride) composites with silver decorated hexagonal boron nitride/silicon carbide hybrid filler

AbstractIn this work, a novel thermal conductive and electrical insulation composite paper fabricated through doctor‐blading followed by hot‐pressing was reported. Specifically, by loading silver nanoparticles (AgNPs) on the surface of boron nitride nanosheets (BNNS) and silicon carbide wires (SiCw), the BNNS and SiCw were bridged through the sintered AgNPs to form a heat conduction path. The results indicate that the prepared composite paper not only enhances the thermal conductivity to 47 W m−1 k−1 but also possesses good mechanical properties and high electrical insulation. The optimizations can be attributed to the efficient BNNS/Ag/SiCw networks within the paper and strong interfacial combination through sintered AgNPs. Furthermore, the distribution and size of the AgNPs also affect the properties of the composites. This work provides a promising strategy to improve thermal conductivity of the composites by constructing efficient thermal conductive pathways, which are suitable for large‐scale preparation and have potential to be widely used in the field of electronic packaging.

Strong and Highly Conductive Poly(vinyl alcohol)/Carbon Dot/EGaIn Composite Films for Flexible and Transient Electronics

Strong and Highly Conductive Poly(vinyl alcohol)/Carbon Dot/EGaIn Composite Films for Flexible and Transient Electronics

Performance Comparison of LMNO Cathodes Produced with Pullulan or PEDOT:PSS Water-Processable Binders

The aim of this paper is to demonstrate lithium metal battery cells assembled with high potential cathodes produced by sustainable processes. Specifically, LiNi0.5Mn1.5O4 (LMNO) electrodes were fabricated using two different water-processable binders: pullulan (PU) or the bifunctional electronically conductive poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The cell performance was evaluated by voltammetric and galvanostatic charge/discharge cycles at different C-rates with 1M LiPF6 in 1:1 (v:v) ethylene carbonate (EC):dimethyl carbonate (DMC) (LP30) electrolyte and compared to that of cells assembled with LMNO featuring poly(vinylidene difluoride) (PVdF). At C/10, the specific capacity of LMNO-PEDOT:PSS and LMNO-PU were, respectively, 130 mAh g−1 and 127 mAh g−1, slightly higher than that of LMNO-PVdF (124 mAh g−1). While the capacity retention at higher C-rates and under repeated cycling of LMNO-PU and LMNO-PVdF electrodes was similar, LMNO-PEDOT:PSS featured superior performance. Indeed, lithium metal cells assembled with PEDOT:PSS featured a capacity retention of 100% over 200 cycles carried out at C/1 and with a high cut-off voltage of 5 V. Overall, this work demonstrates that both the water-processable binders are a valuable alternative to PVdF. In addition, the use of PEDOT:PSS significantly improves the cycle life of the cell, even when high-voltage cathodes are used, therefore demonstrating the feasibility of the production of a green lithium metal battery that can exhibit a specific energy of 400 Wh kg−1, evaluated at the electrode material level. Our work further demonstrates the importance of the use of functional binders in electrode manufacturing.

Flexible Pseudocapacitive Iontronic Tactile Sensor Based on Microsphere‐Decorated Electrode and Microporous Polymer Electrolyte for Ultrasensitive Pressure Detection

AbstractWearable sensor as the initial terminal is in great requirement for people pursuing healthy life. High‐performance tactile sensors are the guarantee of accurate pressure information acquisition. Herein, a flexible iontronic tactile sensor is developed by utilizing a highly conductive poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) thin film decorated with polymethyl methacrylate microspheres as pseudocapacitive electrode and a porous polyurethane foam composited with Na+/Cl−ion‐enriched polyvinyl alcohol gel as polymer electrolyte through a facile method of solution‐casting followed by freeze‐drying. By taking advantages of both high pseudocapacitance and rationally designed microstructures, the developed tactile sensor shows an ultrahigh sensitivity (≈162.90 kPa−1), a broad detection range (≈160 kPa), a low detection limit (≈30 Pa), a fast response time (≈25 ms), and excellent repeatability and durability. Thanks to the ultrahigh sensitivity, the sensor is capable of detecting subtle pressures caused by dynamic micromotions such as touching a sandpaper surface, dropping water droplets, and adding water into a beaker. Application of a smart glove mounted with such sensor unit and array for a fast and accurate Braille recognition is also demonstrated. The proposed facile and efficient strategy of fabricating flexible ultrasensitive tactile sensors will be favorable to various wearable subtle pressure sensing applications.

Enhanced thermoelectric properties of highly conductive poly (3,4-ethylenedioxy thiophene)/exfoliated graphitic carbon nitride composites

In this study, the thermoelectric properties of as-synthesized and –exfoliated graphitic carbon nitride (g-C3N4) filled poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT: PSS) were investigated. Firstly, g-C3N4 was synthesized by heating of guanidine-HCl at 550 °C and exfoliated using an ultrasonic homogenizer. Then, PEDOT:PSS was synthesized by oxidative chemical polymerization. Finally, the composites containing different weight ratios of g-C3N4 were prepared. The conductivity of pristine PEDOT:PSS increased from 11.1 Scm−1 to 722.15 Scm−1 for the composite containing 25% exfoliated g-C3N4, whereas the power factor of PEDOT:PSS increased from 0.19 μWm−1K−2 to 419.7 μWm−1K−2 for the composite containing 15% exfoliated g-C3N4. This study suggests that exfoliated g-C3N4 is a promising material to increase the electrical conductivity and power factor of PEDOT:PSS.

Locally sculptured modification of the electrochemical response of conductive poly(lactic acid) 3D prints by femtosecond laser processing

This manuscript presents an approach to sculpture high electrochemical activity of the 3D printed electrodes with poly(lactic acid) (PLA) matrix and carbon black (CB) filler by femtosecond laser (FSL) ablation. CB-PLA utility for electrochemical applications depends on a surface modification aiming to remove the PLA and uncover the conductive CB. We have discussed how laser pulse energy is critical for such an activation process. The best performance was obtained for 4.1 J cm−2, while scanning electron microscopy (SEM) shows only partial evaporation of PLA at lower energy densities. Next, we have confirmed the efficiency of locally sculptured CB-PLA surface activation by FSL treatment, obtaining high linearity between electrochemically active surface and FSL-treated surface from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. The electrode's efficient sculpturing of stripes 0.2 mm in width was confirmed with electrochemical microscopy (SECM). Finally, by using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, we confirmed no significant oxidation of the CB filler after FSL treatment. We revealed significant differences with ablation by longer nanosecond laser pulses, where significant heat transferred to the electrode surface contributed to partial melting and re-solidification of the PLA, negatively influencing the activation efficiency.

Fabrication of electrically conductive poly(styrene-b-ethylene-ran-butylene-b-styrene)/multi-walled carbon nanotubes composite fiber and its application in ultra-stretchable strain sensor

Although flexible polymer composites based strain sensors have been widely studied, it is still a challenge to obtain flexible strain sensors with large working range, high sensitivity and reliable stability. In this research, a flexible strain sensor based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS)/multi-walled carbon nanotubes (MWCNTs) composite fiber was prepared through the wet spinning method. In particular, the effects of MWCNTs content and aspect ratio (L/D) on the morphology, and mechanical, electrical and electromechanical properties of the composite fiber were studied. The results showed that with the increase of MWCNTs content, the tensile strength and elongation at break of the composite fiber decreased, while the electrical conductivity and the strain sensing range increased. For the same MWCNTs content, the composite fiber filled with MWCNTs of the lowest L/D ratio (1.25/15) showed the highest tensile strength and elongation at break; whereas the composite fiber filled with MWCNTs of the highest L/D ratio (20/15) showed the highest electrical conductivity, strain sensing range (0–506%) and sensitivity (gauge factor of 58.274 at 0%–275% strain, and of 197.944 at 275%–506% strain). The fabricated composite fiber could be formed into a knitted fabric and had the ability of detecting various human motions.

Highly conductive quaternary ammonium-containing cross-linked poly(vinyl pyrrolidone) for high-temperature PEM fuel cells with high-performance

Poly(vinyl pyrrolidone) (PVP)-based high-temperature polymer electrolyte membranes (HT-PEMs) doped with phosphoric acid (PA) present an attractive prospect for high-temperature fuel cell. However, its proton conductivities and mechanical properties are inversely dependent on PVP content in membranes. Herein, chloromethyl-polysulfone is used as a polymeric crosslinker to fabricate cross-linked PVP. The effects of chloromethylation degree of polysulfone on PVP cross-linking degree, free volume and other parameters are studied. The quaternary amine groups introduced by cross-linking reaction enhances PA adsorption and retention capacity of membrane. The increased molar free volume created by polymeric crosslinker can accommodate more PA storage and reduce the polymer main chain plasticization. Thus, the mechanical properties of membranes are maintained. When compared to uncross-linked C-PVP-0/PA, the cross-linked C-PVP-13.7%/PA exhibits improved mechanical strength with increasement of 140% (4.5 MPa) and enhanced proton conductivity with increasement of 119% (120.0 mS cm−1@160 °C). Also, these superior characteristics allow a significantly enhanced H2–O2 fuel cell performance with the membrane of 724.9 mW cm−2 @160 °C, which has increasement of 50% in comparison with that of the C-PVP-0%/PA membrane, and excellent durability. These praiseworthy results suggest that the cross-linked membrane within moderately molar free volume is potential to act as HT-PEMs materials for real-world applications.