A review on electronically conducting polymers for lithium-sulfur battery and lithium-selenium battery:Progress and prospects

Lithium-sulfur(Li-S) batteries and lithium-selenium(Li-Se) batteries,as environmental protection energy storage systems with outstanding theoretical specific capacities and high energy densities,have become the hotspots of current researches.Besides,elemental S(Se) raw materials are widely sourced and their production costs are both low,which make them considered one of the new generations of high energy density electrochemical energy storage systems with the most potential for development.However,poor conductivity of elemental S/Se and the notorious "shuttle effect" of lithium polysulfides(polyselenides) severely hinder the commercialization of Li-S/Se batteries.Thanks to the excellent electrical conductivity and strong absorption of lithium polysulfide(polyselenide) about electronically conducting polymer,some of the above thorny problems have been effectively alleviated.The review presents the fundamental studies and current development trends of common electronically conducting polymers in various components of Li-S/Se batteries,which involves polyaniline(PANI) polypyrrole(PPy),and polythiophene(PTh) with its derivatives,e.g.polyethoxythiophene(PEDOT) and poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS).Finally,the review not only summarizes the research directions and challenges facing the application of electronically conducting polymers,but also looks forward to the development prospects of them,which will provide a way for the practical use of electronically conducting polymers in Li-S/Se batteries with outstanding electrochemical properties in the short run.

Vapor Phase Polymerization Deposition Conducting Polymer Nanocomposites on Porous Dielectric Surface as High Performance Electrode Materials

We report chemical vapor phase polymerization(VPP) deposition of poly(3,4-ethylenedioxythiophene)(PEDOT) and PEDOT/graphene on porous dielectric tantalum pentoxide(Ta_2O_5) surface as cathode films for solid tantalum electrolyte capacitors. The modified oxidant/oxidant-graphene films were first deposited on Ta_2O_5 by dip-coating, and VPP process was subsequently utilized to transfer oxidant/oxidant-graphene into PEDOT/PEDOT-graphene films. The SEM images showed PEDOT/PEDOT-graphene films was successfully constructed on porous Ta_2O_5 surface through VPP deposition, and a solid tantalum electrolyte capacitor with conducting polymer-graphene nano-composites as cathode films was constructed. The high conductivity nature of PEDOT-graphene leads to resistance decrease of cathode films and lower contact resistance between PEDOT/graphene and carbon paste. This nano-composite cathode films based capacitor showed ultralow equivalent series resistance(ESR) ca. 12 m? and exhibited excellent capacitance-frequency performance, which can keep 82% of initial capacitance at 500 KHz. The investigation on leakage current revealed that the device encapsulation process has no influence on capacitor leakage current, indicating the excellent mechanical strength of PEDOT/PEDOT-gaphene films. This high conductivity and mechanical strength of graphene-based polymer films shows promising future for electrode materials such as capacitors, organic solar cells and electrochemical energy storage devices.

Current-voltage characteristics of individual conducting polymer nanotubes and nanowires

We report the current-voltage （I-V） characteristics of individual polypyrrole nanotubes and poly（3,4- ethylenedioxythiophene） （PEDOT） nanowires in a temperature range from 300 K to 2 K. Considering the complex structures of such quasi-one-dimensional systems with an array of ordered conductive regions separated by disordered barriers, we use the extended fluctuation-induced tunneling （FIT） and thermal excitation model （Kaiser expression） to fit the temperature and electric-field dependent I-V curves. It is found that the I-V data measured at higher temperatures or higher voltages can be well fitted by the Kaiser expression. However, the low-temperature data around the zero bias clearly deviate from those obtained from this model. The deviation （or zero-bias conductance suppression） could be possibly ascribed to the occurrence of the Coulomb-gap in the density of states near the Femi level and/or the enhancement of electron-electron interaction resulting from nanosize effects, which have been revealed in the previous studies on low-temperature electronic transport in conducting polymer films, pellets and nanostructures. In addition, similar I--V characteristics and deviation are also observed in an isolated K0.27MnO2 nanowire.

STUDIES ON ENHANCED CONDUCTIVITY OF STRETCHED CONDUCTING POLYMERS

A physical model of series of the conductivity on chain and the interchain conductivitybetween chains is proposed to explain enhanced conductivity of stretched conducting polymers.This model suggests that the enhanced conductivity for stretched conducting polymers might bedue to increasing of the interchain conductivity between chains along the elongation direction afterdrawing processes if the conductivity on chain is assumed much larger than that of the interchainconductivity between chains. According to this model, it is expected that the temperaturedependence of conductivity measured by four-probe method for stretched conducting polymers iscontrolled by a variation of the interchain conductivity between chains with temperature, whichcan be used to explain that a metallic temperature dependence of conductivity for stretchedconducting polymers is not observed although the conductivity along the elongation direction isenhanced by two or three orders of magnitude.

INFRARED EMISSIVITY OF CONDUCTING POLYMERS

The infrared emissivity of conducting polymers in 8—20μm and at 50—150℃ in the direction of normal line has been measured as a function of wavelength, conductivity at room temperature, counterion, doping levels, measuring temperature and thickness of sample.

Electrochemical Impedance Analysis of Biofunctionalized Conducting Polymer-Modified Graphene-CNTs Nanocomposite for Protein Detection

We report an electrodeposited poly(pyrrole-co-pyrrolepropylic acid) copolymer modified electroactive graphene-carbon nanotubes composite deposited on a glassy carbon electrode to detect the protein antigen(cTnI). The copolymer provides pendant carboxyl groups for the site-specific covalent immobilization of protein antibody, antitroponin I. The hybrid nanocomposite was used as a transducer for biointerfacial impedance sensing for cTnI detection.The results show that the hybrid exhibits a pseudo capacitive behaviour with a maximum phase angle of 49° near 1 Hz,which is due to the inhomogeneous and porous structure of the hybrid composition. The constant phase element of copolymer is 0.61(n = 0.61), whereas, it is 0.88(n = 0.88) for the hybrid composites, indicating a comparatively homogeneous microstructure after biomolecular functionalization. The transducer shows a linear change in charge transfer characteristic(R_(et)) on cTnI immunoreaction for spiked human serum in the concentration range of 1.0 pg mL^(-1)–10.0 ng mL^(-1). The sensitivity of the transducer is 167.8 ± 14.2 Ω cm^2 per decade, and it also exhibits high specificity and good reproducibility.

Characteristics and Application of Conducting Polymer Sensor

Conducting polymers sensors have been very interesting that it can detect wide variety of functionalities,however these materials have to solve humidity contaminant,poor reversibility and selectivity.To improve this problems,we investigated pretreatment such as soaking in methanol and thermal treatment in N_2.This process improved stability, reversibility and response time and recovery time.To overcome humidity contaminant coated hydrophobic polymer was reduced above 50% at RH10%.For sensor array structure was fabricated for enhancing selectivity of gas vapor.Conducting polymer sensor array had several application in environmental and medical science the method of principal component analysis.

Electrochemical Formation of Polypyrrole-carboxymethylcellulose Conducting Polymer Composite Films

The electrochemical preparation of polypyrrole-carboxymethylcellulose （PPY-CMC） conducting polymer composite films on indium tin oxide （ITO） glass electrode from an aqueous solution containing pyrrole monomer, ptoluenesulfonate electrolyte and carboxymethylcellulose insulating polymer is reported. The characterization by Fourier transform infrared spectroscopy （FT-IR） shows that carboxymethylcellulose （CMC） has been successfully incorporated into polypyrrole structure forming PPY-CMC polymer composite films. The conductivity of the prepared composite films was found to increase with increaseing CMC concentration in pyrrole solution, The optical microscopic results show the influence of CMC concentration in the pyrrole solution over the morphological changes of the prepared films. The dynamic mechanical analysis （DMA） on the prepared PPY-CMC film reveals the higher plastic property of the PPY-CMC composite film.

Rectifying effect of heterojunctions between metals and doped conducting polymer nanostructure pellets

This paper reports that the Schottky junctions between low work function metals （e.g. Al and In） and doped semiconducting polymer pellets （e.g. polyaniline （PANI） microsphere pellet and polypyrrole （PPy） nanotube pellet） have been prepared and studied. Since Ag is a high work function metal which can make an ohmic contact with polymer, silver paste was used to fabricate the electrodes. The Al/PANI/Ag heterojunction shows an obvious rectifying effect as shown in I - V characteristic curves （rectifying ratio γ = 5 at ±6 V bias at room temperature）. As compared to the Al/PANI/Ag, the heterojunction between In and PANI （In/PANI/Ag） exhibits a lower rectifying ratio γ= 1.6 at ±2 V bias at room temperature. In addition, rectifying effect was also observed in the heterojunctions Al/PPy/Ag （γ = 3.2 at ±1.6 V bias） and In/PPy/Ag （γ = 1.2 at ±3.0 V bias）. The results were discussed in terms of thermoionic emission theory.

MEASUREMENT METHOD AND PHYSICAL MODEL OF VSC CONDUCTIVITY AND ITS APPLICATIONS IN CONDUCTING POLYMERS

Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.

Towards Ultrahigh Capacity and High Cycling Stability Lithium-Conducting Polymer Batteries by In Situ Construction of Nanostructured Porous Cathodes

Conducting polymers(CPs)have long been studied as cathode materials for lithium-ion batteries,but the low doping level(maximum:30–50%or even lower)and poor cycling stability limit their applications.Herein,we have developed a method of nanoporeconfined in situ electropolymerization to prepare nanostructured polythiophene-type porous cathodes,achieving significantly improved doping availability and long cycle life.It was verified that the nanosized polymer formed in situ and loose porous structure are conducive to the doping reaction and maintain high electrochemical stability.The constructed thieno[3,2-b]thiophene(TtTP)/active carbon cathode delivers an ultrahigh reversible capacity of 309.2 mAh g^(−1)(doping level up to 80.9%)along with an ultrahigh energy density of 1252.3 Wh Kg^(−1),and an ultrahigh rate capability(172.4 mAh g^(−1) at 30 A g^(−1)),which far exceed all the CPs and even all the p-type organic cathode materials reported.Moreover,an excellent long cycle life of 2000 cycles at 5 A g^(−1) is also revealed,which is a new record for CPs-based cathode materials in nonaqueous lithium-ion batteries.Our method provides an effective strategy to improve the doping level and cycling stability of CP-based cathode materials.

Solution-processed wafer-scale nanoassembly of conducting polymers enables selective ultratrace nerve agent detection at low power

There is a great interest in developing microelectronic devices based on nanostructured conducting polymers that can selectively electro-couple analytes at high sensitivity and low power.Nanostructured conducting polymers have emerged as promising candidates for this technology due to their excellent stability with low redox potential,high conductivity,and selectivity endowed by chemical functionalization.However,it remains challenging to develop cost-effective and large-scale assembly approaches for functionalized conducting polymers in the practical fabrication of electronic devices.Here,we reported a straightforward waferscale assembly of nanostructured hexafluoroisopropanol functionalized poly(3,4-ethylenedioxythiophene)(PEDOT-HFIP)on smooth substrates.This approach is template-free,solution-processed,and adaptable to conductive and nonconductive substrates.By this approach,the nanostructured PEDOT-HFIPs could be easily integrated onto interdigitated electrodes with intimate ohmic contact.At the optimized space-to-volume ratio,we demonstrated a low-power,sensitive,and selective nerve agent sensing technology using this platform by detecting sarin vapor with a limit of detection(LOD)of 10 ppb and signal strength of 400 times the water interference at the same concentration,offering significant advantages over existing similar technologies.We envision that its easy scale-up,micro size,small power consumption,and combination of high sensitivity and selectivity make it attractive for various wearable platforms.

Chemically revised conducting polymers with inflammation resistance for intimate bioelectronic electrocoupling

Conducting polymers offer attractive mixed ionic-electronic conductivity,tunable interfacial barrier with metal,tissue matchable softness,and versatile chemical functionalization,making them robust to bridge the gap between brain tissue and electronic circuits.This review focuses on chemically revised conducting polymers,combined with their superior and controllable electrochemical performance,to fabricate long-term bioelectronic implants,addressing chronic immune responses,weak neuron attraction,and long-term electrocommunication instability challenges.Moreover,the promising progress of zwitterionic conducting polymers in bioelectronic implants(≥4 weeks stable implantation)is highlighted,followed by a comment on their current evolution toward selective neural coupling and reimplantable function.Finally,a critical forward look at the future of zwitterionic conducting polymers for in vivo bioelectronic devices is provided.

Ultralow fouling electrochemical detection of uric acid directly in serum based on phase-transited bovine serum albumin and conducting polymer

Electrochemistry with antifouling sensing interfaces that effectively resist the adsorption of nonspecific biomolecules provides a powerful mean for the accurate and sensitive detection of disease biomarkers tive dete in complex biofluids.However.there are few strategies to acquire a stable and solid antifouling coat-ing on any substrate by a simple way.Herein,a simple one-step assembly methød has been adopted to construct phase-transited bovine serum albumin(PTB)antifouling Layers.Prior to construction of the an-tifouling layers.the poly(3,4-ethylenedioxythiophene)(PEDOT)doped with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(ionic liquid,IL)were firstly electrodeposited on bare electrodes,en-dowing good conductiviry and catalytic capability for the developed sensor.Subsequently.with the assist of tris(2-carboxyethyl)phosphine(TCEP)the disulfide bonds of bovine serum albumin(BSA)were re-Im alb duced to form PTB,which can be coated on the PEDOT-It modified electrode to construct an antifouling electrochemical senor(PTB/PEDOT-ILCCE)for the detection of uric acid(UA)in human serum.The UA sensor demonstrated a good linear range from 1.11 umol/L to 798.9 umol/L with a high sensltivity of0,556 jA umolL^(-1)cm^(-2).The combination of conducting polymers with one-step assembly of PTB offers a universal and rellable method før the modification of various electrodes to determine target molecules in complex human body fluids.

Alcohol-dispersed polymer complex as an effective and durable interface modifier for n-i-p perovskite solar cells

Abundant interfacial defects remain a significant challenge that hampers both the efficiency and stability of perovskite solar cells(PSCs).Herein,an alcohol-dispersed conducting polymer complex,denoted as PEDOT:F(Poly(3,4-ethylene dioxythiophene):Perfluorinated sulfonic acid ionomers),is introduced into the interface between perovskite and hole transporting layer in regular-structured PSCs.PEDOT:F serves as a multi-functional interface layer(filling grain boundaries and covering perovskite's grain-surface)to achieve a robust interaction with organic groups within perovskites,which could induce a structural transformation of PEDOT to increase its conductivity for the efficient hole-transport.Furthermore,the strong interaction between PEDOT and perovskites could promote an effective coupling of undercoordinated Pb~(2+)ions with the lone electron pairs near O&S atoms in PEDOT molecules,thereby enhancing defect passivation.Additionally,PEDOT:F with inherent hydrophobic properties prevents effectively moisture invasion into perovskites for the improved long-term stability of the PSCs.Consequently,the PEDOT:F-based PSCs achieved a champion efficiency of 24.81%,and maintained ca.92%of their initial efficiency after 7680 h of storage in a dry air environment,accompanied by the enhanced photothermal stability.

Ignition processes and characteristics of charring conductive polymers with a cavity geometry in precombustion chamber for applications in micro/nano satellite hybrid rocket motors

The arc ignition system based on charring polymers has advantages of simple structure,low ignition power consumption and multiple ignitions,which bringing it broadly application prospect in hybrid propulsion system of micro/nano satellite.However,charring polymers alone need a relatively high input voltage to achieve pyrolysis and ignition,which increases the burden and cost of the power system of micro/nano satellite in practical application.Adding conductive substance into charring polymers can effectively decrease the conducting voltage which can realize low voltage and low power consumption repeated ignition of arc ignition system.In this paper,a charring conductive polymer ignition grain with a cavity geometry in precombustion chamber,which is composed of PLA and multiwall carbon nanotubes(MWCNT)was proposed.The detailed ignition processes were analyzed and two different ignition mechanisms in the cavity of charring conductive polymers were revealed.The ignition characteristics of charring conductive polymers were also investigated at different input voltages,ignition grain structures,ignition locations and injection schemes in a visual ignition combustor.The results demonstrated that the ignition delay and external energy required for ignition were inversely correlated with the voltages applied to ignition grain.Moreover,the incremental depth of cavity shortened the ignition delay and external energy required for ignition while accelerated the propagation of flame.As the depth of cavity increased from 2 to 6 mm(at 50 V),the time of flame propagating out of ignition grain changed from 235.6 to 108 ms,and values of mean ignition delay time and mean external energy required for ignition decreased from 462.8 to 320 ms and 16.2 to 10.75 J,respectively.The rear side of the cavity was the ideal ignition position which had a shorter ignition delay and a faster flame propagation speed in comparison to other ignition positions.Compared to direct injection scheme,swirling injection provided a more favorable flow field environment in the cavity,which was beneficial to ignition and initial flame propagation,but the ignition position needed to be away from the outlet of swirling injector.At last,the repeated ignition characteristic of charring conductive polymers was also investigated.The ignition delay time and external energy required for ignition decreased with repeated ignition times but the variation was decreasing gradually.

Highly Elastic,Bioresorbable Polymeric Materials for Stretchable,Transient Electronic Systems

Substrates or encapsulants in soft and stretchable formats are key components for transient,bioresorbable electronic systems;however,elastomeric polymers with desired mechanical and biochemical properties are very limited compared to nontransient counterparts.Here,we introduce a bioresorbable elastomer,poly(glycolide-co-ε-caprolactone)(PGCL),that contains excellent material properties including high elongation-at-break(<1300%),resilience and toughness,and tunable dissolution behaviors.Exploitation of PGCLs as polymer matrices,in combination with conducing polymers,yields stretchable,conductive composites for degradable interconnects,sensors,and actuators,which can reliably function under external strains.Integration of device components with wireless modules demonstrates elastic,transient electronic suture system with on-demand drug delivery for rapid recovery of postsurgical wounds in soft,time-dynamic tissues.

Nanoscale engineering of conducting polymers for emerging applications in soft electronics

Soft electronics featuring exceptional mechanical compliance and excellent electrical performance hold great promise for applications in soft robotics,artificial intelligence,bio-integrated electronics,and wearable electronics.Intrinsically stretchable and conductive materials are crucial for soft electronics,enabling large-area and scalable fabrication,high device density,and good mechanical compliance.Conducting polymers are inherently stretchable and conductive.They can be precisely synthesized from vastly available building blocks,and thus they provide a fruitful platform for fabricating soft electronics.However,amorphous bulk-phase conducting polymers typically exhibit poor mechanical and electrical characteristics.Consequently,it is highly desirable to develop novel engineering approaches to overcome the intrinsic limitations of conducting polymers.In recent years,numerous engineering strategies have been developed to enhance their performances in soft electronic devices via constructing various nanostructures.In this review,we first summarize several unique methodologies to fabricate conducting polymer-based nanostructures.We then discuss how nanoscale engineering approaches can improve several crucial parameters,including electrical conductivity,stretchability,sensitivity,and self-healing property of conducting polymers.Moreover,we also discuss device-level integration of conducting polymer-based nanostructures with other materials for applications in skin-inspired electronics and bio-integrated electronics.Finally,we provide perspectives on challenges and future directions in engineering nanostructured conducting polymers for soft electronics.

Semiconducting covalent organic frameworks:a type of two-dimensional conducting polymers

In recent years,as a new class of two-dimensional polymer,covalent organic frameworks（COFs） have attracted intensive attention and developed rapidly.This review provides an overview of a type of COFs which can be utilized as organic semiconductors.Carefully choosing monomers as the building blocks will bestow different types of semiconducting character on COFs.We summarize the p-type,n-type and ambipolar semiconducting COFs and highlight the effects of π-functional building blocks on the photoconductive behaviors of the semiconducting COFs.