全固态聚合物锂电池的科研进展、挑战与展望CSCD

锂离子电池已经广泛地应用于国民经济的诸多方面。然而,随着消费电子产品和电动汽车对锂离子电池能量密度和安全性能要求的不断提升,开发兼顾两者性能的高性能锂离子电池迫在眉睫。基于传统液态有机碳酸酯类电解液的锂离子电池存在电解液泄漏、挥发、燃烧、爆炸等潜在安全隐患。相对于无机全固态锂电池而言,全固态聚合物锂电池更容易大规模制造,是实现锂电池高能量密度和高安全性的相对理想的解决方案。作为全固态聚合物锂电池的最核心部件,全固态聚合物电解质起着至关重要的作用。基于此,本文重点论述了聚环氧乙烷、聚硅氧烷、脂肪族聚碳酸酯等几种典型全固态聚合物电解质的科研进展。与此同时,还对近几年国内外知名公司企业以及科研院所在全固态聚合物锂电池方面的技术应用现状和专利布局进行了系统分析。文末还对全固态聚合物锂电池用高性能全固态聚合物电解质的设计制备、新型锂盐开发、正极材料黏结剂、负极优化、界面构筑调控、制备成型工艺等方面面临的主要挑战和发展趋势进行了阐述。     

Patternable solution process for fabrication of flexible polymer solar cells using PDMS

PH 500, a highly conducting poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), is a typical conducting polymer anode material used in organic electric devices. However, it has the disadvantages of low conductivity and poor surface roughness and requires a patterning method for the electrode through including the laser and plasma. In this paper, therefore, the conducting polymer ink for a transparent anode was formulated by adding dimethyl sulfoxide (DMSO) and BYK-333 as the surfactant to enhance the conductivity and surface roughness. The conducting polymer anode was patterned through the application of a new patterning method that used polydimethylsiloxane (PDMS) on a flexible substrate. In addition, a photoactive layer was formed by applying the new patterning method to the conventional brush painting method in which patterning had previously been impossible. The resulting material was compared with the device fabricated by the spin coating method. The fabricated flexible polymer solar cells (PSCs) exhibited short-circuit current density (J_sc), open-circuit voltage (V_oc), fill factor (FF) and power conversion efficiency (PCE) values of 4.2 mA/cm², 0.878 V, 26.5% and 0.98%, respectively, which represented an efficiency improvement of 38% over those fabricated by the spin coating method. Meanwhile, the J_sc value was increased when the series resistance (R_s) decreased to 150 Ω cm².     

Metal phthalocyanine-linked conjugated microporous polymer hybridized with carbon nanotubes as a high-performance flexible electrode for supercapacitors

Metal phthalocyanine-linked conjugated microporous polymers (MPc-CMPs) have huge potential applications in energy conversion and storage systems. However, the inherent low conductivity limits their practical application. Herein, the MPc-CMPs are hybridized with highly conductive carbon nanotubes (CNTs) via the easy vacuum filtration method. Interestingly, the composite (denoted as CoPc-CMP/CNTs) shows the flexible feature, which can be served as the flexible binder-free electrode for supercapacitors (SCs). As expected, the flexible CoPc-CMP/CNTs exhibits a high specific capacitance of 289.1 F g⁻¹ at a current density of 1 A g⁻¹ and good capacity retention of 82.4% over 1350 cycles at a high current density of 10 A g⁻¹. Furthermore, First-principle calculations are used to elucidate the superiority of CoPc-CMP to other analogues. The good electrochemical performance could be attributed to the synergistic effect from the high pseudocapacitance and good conductivity of CoPc-CMP as well as the capacitive contribution and good conductivity of CNTs. Our strategy provides a new avenue to develop the high-performance SCs via rational integration of MPc-CMPs with highly conductive CNTs.     

Comparison of solar cell performance of conducting polymer dyes with different functional groups

Conductive polymer precursors, including carboxylic acid, cyano groups, amino groups, 5,2′:5′,2″-terthiophene-3′-carboxylic acid (TTCA), 3′-cyano-5,2′:5′,2″-terthiophene (CTT), and 3′,4′-diamino-2,2′:5′,2″-terthiophene (DATT) are synthesized. Electrochemically polymerized films of the precursors on a nanocrystalline TiO₂ layer are examined as photo sensitizers, and the cell performance is compared. The photovoltaic cells are assembled with a polymer-coated TiO₂ layer treated with TiCl₄ as an anode and a Pt layer as a cathode in a propionitrile solution containing an iodide ion-based redox electrolyte. The charge-transfer processes of polymer-dyed cells are studied using impedance spectroscopy. The polymer dyes on the TiO₂ surfaces are characterized by scanning electron microscope (SEM), atomic force microscope (AFM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). XPS results show that the conducting polymer dye, bearing a carboxylic acid group, is more strongly bound to the TiO₂ layer in comparison with other groups. Various experimental parameters affecting the cell efficiency are optimized, including the scan rate, number of potential cycles, and terthiophene monomer concentration. Of these polymers, the best cell efficiency is attained for poly-TTCA containing a carboxylic acid group. The optimized cell with the poly-TTCA dye shows a short-circuit current of 6.78 mA cm⁻², an open-circuit voltage of 0.54 V, and a fill factor of 63.6. An energy conversion efficiency of 2.32% is obtained with a cell area of 0.24 cm² under an air mass 1.5 solar simulated light irradiation of 100 mW cm⁻².     

Patternable brush painting process for fabrication of flexible polymer solar cells

The brushing painting method is one of the typical solution processes, which makes it possible to fabricate electronic devices by simply using polymers. For the fabrication of modules and large-area devices, however, a patterning process is required for each layer. Due to the problems associated with the conventional patterning, many studies have been conducted to develop new patterning . In this study, we successfully fabricated bulk heterojunction (BHJ) structured polymer solar cells (PSCs) on a plastic substrate with an active layer through the brushing painting process. In particular, flexible PSCs with hole transporting and photo-active layers formed by the repositionable adhesive-based patterning method were fabricated to produce large-area solar cells. The fabricated PSCs exhibited Jsc, Voc, FF and power conversion efficiency (PCE) values of 8.5 mA/cm², 0.636 V, 48.8% and 2.6%, respectively. In other words, they were more efficient than those fabricated by the spin coating method. In particular, an increase in the Jsc and FF values was observed when the series resistance (Rs) decreased to 29 Ω cm² while the shunt resistance (Rsh) increased to 2018 Ω cm².     

Synthesis of three-dimensional graphene@Ni(OH)2 nanoflakes on Ni foam by RF magnetron sputtering for application in supercapacitor

Three-dimensional graphene@Ni(OH)₂ nanoflake array grown on Ni foam (G/Ni(OH)₂/NF) as a binder-free electrode of supercapacitor was prepared by combining a one-step hydrothermal approach and Radio frequency (RF) magnetron sputtering technique. Its electrochemical properties were further investigated by the cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectra. The G/Ni(OH)₂/NF showed high specific capacitance (4.0F/cm² at 1.0 mA/cm²), good rate charge-discharge capability and long cycling stability (ca. 90.6% of its initial value). This work provides a new method to prepare 3D porous electrode materials based on graphene for application in electrochemical energy storage.     

Green and facile synthesis of porous carbon spheres from waste solution for high performance all-solid-state symmetric supercapacitors

Porous carbon spheres materials display huge potential for energy storage, but their general synthesis need chemical activation agent with highly corrosive to create pores. In this work, a simple, environment-friendly and less time-demanding method is used to prepared porous carbon spheres using K₂FeO₄ as activation agent and waste solution as the precursor. The K₂FeO₄ employ in this work acts both as an activating agent and a catalyst. In addition, replacing KOH with K₂FeO₄ does not only reduce the corrosion of equipment but also increases the content of oxygen. The optimized porous carbon spheres with high specific surface area, hierarchical pore structure and surface heteroatom can deliver a high specific capacitance of 260 F g⁻¹ at 0.1 A g⁻¹ and good cycling stability (90% retention after 15000 cycles at 5 A g⁻¹). Furthermore, the all-solid-state symmetric supercapacitors fabricated based on as-prepared samples exhibit good electrochemical performance in the PVA/KOH electrolyte. This work offers a green route to convert waste solution into porous carbon spheres, which are promising candidate material for supercapacitors to energy storage.     

Single-step hydrothermal synthesis of WO3-MnO2 composite as an active material for all-solid-state flexible asymmetric supercapacitor

In present study, new strategy is employed to build composite nanostructure and asymmetric configuration to enhance the capacitive performance of supercapacitor device. The WO₃-MnO₂ composite with mesoporous structure is prepared by single-step hydrothermal method and used to gain superior electrochemical performance in asymmetric configuration. A binder-free and additive-less WO₃-MnO₂ composite electrode exhibits high specific capacitance of 609 F g^?1 at a scan rate of 5 mV s^?1. The flexible asymmetric supercapacitor device with WO₃-MnO₂ as a positive electrode and WO₃ as a negative electrode demonstrates stable operating potential window of 1.4 V with specific capacitance of 103 F g^?1 at a scan rate of 5 mV s^?1 and energy density of 24.13 Wh kg^?1 at power density of 915 W kg^?1. Furthermore, WO₃-MnO₂//WO₃ device exhibits good cycle life with capacity retention of 95% after 2500 cycles and excellent mechanical flexibility. These results reveal the potential of WO₃-MnO₂ composite electrode for fabrication of high-performance supercapacitors.     

Supercritical fluid processing of N-doped graphene and its application in high energy symmetric supercapacitor

A simple one-pot methodology is developed for the synthesis of nitrogen doped graphene via supercritical fluid (SCF) processing using glycine as a nitrogen precursor. The presence of various N-containing functional groups was determined by FT-IR and the amount of N-doping in the graphene was found to be 4.5 wt% using the elemental analysis and X-ray photoelectron spectroscopy. The electrochemical capacitance measurements are performed using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The nitrogen doped graphene exhibited enhanced capacitive performance with a maximum specific capacitance of 270 F/g at 0.5 A/g current density with high specific capacitance retention of 90% over 10,000 cycles at 10 A/g current density. The fabricated symmetric supercapacitor cell showed a high energy density of 4.1 and 36 Wh/kg in aqueous and ionic liquid electrolyte, respectively. The high energy density obtained in ionic liquid is promising for their potential application in electrochemical energy system.     

Synthesis of Fe3O4 nanocubes anchored in MgCo2O4 nanoneedle arrays for flexible all-solid-state asymmetric supercapacitor

The design of novel heterostructure with multifunctional characteristics is of great technical significance for the development of new energy storage devices. However, the lower conductivity of metal oxides and the accumulation caused by irreversible phase transition after multiple cycles are the main reasons for the low specific capacitance and cycle life. Herein, we synthesized bimetallic oxide MgCo₂O₄ nanoneedles with a spinel structure, and firmly anchored Fe₃O₄ nanocubes on MgCo₂O₄ nanoneedles by ion-exchange strategy. Thanks to the constructed heterostructure of nanoneedles/nanocubes, the introduction of Fe₃O₄ effectively improves the electron transport path in MgCo₂O₄ during repeated charging and discharging, and increases the effective activation sites involved in electron transfer. As a result, a higher specific capacitance of 1648 F g^?1 at 1 A g^?1 and an ultra-long cycle life of 78.6% capacitance retention after 6000 continuous charge/discharge cycles are obtained. A flexible all-solid-state asymmetric supercapcitor assembled with MgCo₂O₄-Fe₃O₄ as positive electrode and AC as negative electrode can deliver an ultra-high energy density of 78 Wh kg^?1 and maximum power density of 1.2 kW kg^?1, as well as extraordinary capacitive retention of 75.2% after 10,000 cycles. These excellent properties reveal the potential and application value of MgCo₂O₄-Fe₃O₄ in the development of high-performance supercapacitors.     

Optically active polymer nanocomposite composed of polyaniline,polyacrylonitrile and green-synthesized graphene quantum dot for supercapacitor application

Development of stable and optically active composite film that can show efficient supercapacitor activity is a challenging research interest in material science. A polymer nanocomposite film composed of a green synthesised graphene quantum dot (GQD, G) doped polyacrylonitrile (PAN) and polyaniline (PANI) systems, designated as PAN-PANI@G, have been prepared. The critical loading concentration of prepared composite and its effect on the physicochemical, optical and electrical analysis were systematically studied in detail. PAN-PANI@G composite showed an appreciable electrical conductivity (2.362 × 10⁻⁶ S m⁻¹) and optical absorbance at λ_max ~270 nm. Physicochemical characterizations by XRD, FTIR and TEM analysis reveal chemical interaction between the individual components via intermolecular hydrogen bonding. Analysed particle size of GQD in the polymer membrane was found to be about two times lesser than that of the pure GQD highlighting synergic interaction between the individual GQD and PAN/PANI matrix. A specific capacitance value of the polymer composites that have been modified on screen-printed carbon electrode were tested by cyclic voltammetric and galvanostatic charge-discharge techniques in 0.1 M H₂SO₄ solution. Calculated supercapacitor values at an applied current density, 670 mA g⁻¹ are in a range of 105–587 F g⁻¹ cm⁻² which are approximately 2–1300 times higher than the values reported for polypyrrole and polyaniline based polymer composite film in the literature. As a preliminary extension of this study, the optimal PAN/PANI@G nanocomposite of GQD loading, 1.5 wt% was extended to prototype supercapacitor cell application in combination with a dilute solution of NaCl along with suitable conducting plates. When 3 V DC power was supplied for 4 min, the prototype cell produced an operating voltage of 1.4 V for 1 h of operating time.     

Mathematical functions for optimisation of conducting polymer/activated carbon asymmetric supercapacitors

Equations routinely used to describe the properties of conventional symmetric electrochemical double-layer capacitors (EDLCs) are expanded to develop straightforward mathematical functions that can effectively describe the performance characteristics of asymmetric supercapacitors based on electrically conducting polymer and activated carbon (ECP–AC) electrodes. Formulae are developed to describe cell parameters (based on total active material mass) such as maximum specific capacitance (F g⁻¹), maximum specific energy (Wh kg⁻¹), and optimum electrode mass ratios that can be used for maximising the specific energy of asymmetric cells. The electrode mass ratios are found to have a significant impact on the swing voltages across the positive and negative electrodes. Illustrative EDLC and ECP–AC devices are explored and employed to verify the derived equations that serve to predict essential parameters of both symmetric and asymmetric systems, irrespective of electrolyte ion concentration, solvent or species and independent of voltage. The utility of the equations is demonstrated by predicting cell parameters for a number of theoretical asymmetric ECP–AC systems and used to correlate experimentally obtained parameters.     

Photo-polymerized films of lithium ion conducting solid polymer electrolyte for electrochromic windows (ECWs)

Films of solid polymer electrolyte (spe) have been prepared by the photo-polymerization of the monomer: 2-hydroxyethylmethacrylate (HEMA) simultaneously accompanied by chemical crosslinking with neopentyl glycol which is dissolved in a liquid electrolyte, namely, 1 M LiClO₄ in EC:PC binary solvent mixed in two different volume ratios. The spe films exhibit ionic conductivities greater than 10⁻³ Scm⁻¹ at 25°C. Thermal and structural characteristics of the films have been determined by DSC and XRD, respectively. The electrochemical redox behavior of an electrochromic device (PWECD) fabricated with an electrodeposited tungsten oxide film as the primary electrode, a prussian blue film as the counter electrode and a poly(HEMA) based electrolyte film as well as that of the individual components of the device has been examined by cyclic voltammetry. Transmission modulation of 60% (λ=650 nm) shown by the PWECD renders it to be a promising candidate for electrochromic window applications.     

Aero-elastic behavior of a flexible blade for wind turbine application: A 2D computational study

This paper presents a computational study into the static aeroelastic response of a 2D wind turbine airfoil under varying wind conditions. An efficient and accurate code that couples the X-Foil software for computation of airfoil aerodynamics and the MATLAB PDE toolbox for computation of the airfoil deformation is developed for the aero-elastic computations. The code is validated qualitatively against computational results in literature. The impact of a flexibility of the airfoil is studied for a range of design parameters including the free stream velocity, pitch angle, airfoil thickness, and airfoil camber. Static aero-elastic effects have the potential to improve lift and the lift over drag ratio at off-design wind speed conditions. Flexibility delays stall to a large pitch angle, increasing the operating range of a flexible blade airfoil. With increased thickness the airfoil deformation decrease only linearly.     

Microwave synthesis of Sb2Se3/polyacrylonitrile-based carbon fiber mat electrodes for high-performance flexible capacitors and hydrogen evolution reaction

The development of bifunctional electrodes with good capacitive performance and efficient hydrogen evolution reaction activity is one of the potential solutions to combat energy depletion. In this study, flexible polyacrylonitrile-based carbon fiber mat with nitrogen doping and oxygen-containing functional group carbon structure was selected as the flexible substrate, and binder-free flexible Sb₂Se₃/polyacrylonitrile-based carbon fiber mat composite electrode was successfully prepared within 120 s using microwave synthesis. The electrode not only has a capacitance of 478.0C g^?1 and retains 97.4% of the initial capacitance after 50,000 charge–discharge tests but also exhibits good HER activity of low overpotential (152 mV) and Tafel slope (78.4 mV/dec) in alkaline electrolyte. The performance of the assembled flexible asymmetric supercapacitor is almost unaffected by bending up to 180°. The device has an energy density of 21.3 Wh kg^?1 at a power density of 800.0 W kg^?1, indicating that the electrode has good prospects for portable energy storage applications.     

Highly efficient catalytic derived synthesis process of carbon aerogel for hydrogen storage application

For the present work, resorcinol-formaldehyde (R–F) aerogels were synthesized through both acid (nitric acid) and base (sodium carbonate) catalyzed sol-gel process followed by supercritical drying (SCD) as well as ambient pressure drying (APD). RF aerogels were carbonized at high temperatures to form carbon aerogels. The effect of the catalyst type and drying methods on the final characteristics were studied in detail. Microstructural and textural characteristics were evaluated through XRD, SEM, BET, RAMAN, FTIR, and TEM techniques. It was found that the combination of base catalysis and SCD delivered a higher micropore density and more uniform pore distribution. The CAs prepared under such conditions displayed a hydrogen uptake of 0.80 wt% at room temperature and 2.85 wt% at liquid nitrogen temperature (77 K).     

High-temperature,polymer–graphite hybrid composites for bipolar plates: Effect of processing conditions on electrical properties

High-temperature thermoplastic–graphite composites are prepared using polyphenylene sulfide (PPS) and polyether sulfone (PES) containing natural graphite powder. All samples are prepared by high pressure compaction and heating to high temperatures. The effect of a third additional conducting component on the electrical resistance of these composites is studied. A low resistance of the order of 0.1 Ω can be obtained even for a graphite concentration of 50% by addition of the third component. The effect of a mixing/blending technique on the anisotropy of conductivity is investigated. Solution blending of PES with graphite leads to lower anisotropy values than powder mixing and compression moulding. The samples when exposed continuously to a working temperature of 100 °C give a small but significant reduction in electrical resistance. X-ray diffraction studies on composites prepared by different techniques indicate that there is restructuring and crystallite re-orientation of the graphite phase in the samples. A large reduction in the crystallite size is observed for samples prepared by solution blending while re-orientation occurs after heat treatment. The changes in electrical properties can be correlated with these structural transformations in the composites.     

Construction of composite electrodes comprising manganese dioxide nanoparticles distributed in polyaniline-poly(4-styrene sulfonic acid-co-maleic acid) for electrochemical supercapacitor

This work demonstrated a novel and simple route for preparing a composite comprising of manganese oxide (MnO₂) nanoparticles and polyaniline (PANI) doped poly(4-styrene sulfonic acid-co-maleic acid) (PSSMA) by “electrochemical doping-deposition”. The PANI-PSSMA-MnO₂ composite was characterized by scanning electron microscopy (SEM)), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). SEM images revealed a uniform dispersion of MnO₂ nanoparticles in the porous structure of PANI-PSSMA structure. XRD measurements showed the distortion of the crystal structure of β-MnO₂ after deposition of MnO₂ in PANI-PSSMA structure. Thus, the XRD pattern of PANI was predominating. Cyclic voltammetry and chronopotentiometry were employed in 0.5 M Na₂SO₄ to evaluate the capacitor properties. The results showed a significant improvement in the specific capacitance of the composite electrode. The specific capacitance of PANI-PSSMA-MnO₂ (50.4 F g⁻¹) had improvement values of 172% compared to that of PANI (18.5 F g⁻¹). When only the MnO₂ mass was considered, the composite had a specific capacitance of 556 F g⁻¹.     

Sol-gel synthesis of Er3+:Y3Al5O12/TiO2Ta2O5/MoO2 composite membrane for visible-light driving photocatalytic hydrogen generation

By using TiO₂ and Ta₂O₅ colloids, a stable and efficient visible-light driven photocatalyst, Er³⁺:Y₃Al₅O₁₂/TiO₂Ta₂O₅/MoO₂ composite membrane, was successfully prepared via sol–gel dip coating method at room temperature. The XRD, FTIR, SEM, TEM and EDX results confirm that approximately spherical Er³⁺:Y₃Al₅O₁₂ nanoparticles were embedded in TiO₂Ta₂O₅ matrix. UV–vis absorption and PL spectra of Er³⁺:Y₃Al₅O₁₂ were also determined to confirm the visible absorption and ultraviolet emission. The photocatalytic hydrogen generation was carried out by using methanol as sacrificial reagent in aqueous solution under visible-light irradiation. Furthermore, some main influence factors such as heat-treated temperature, heat-treated time and molar ratio of TiO₂ and Ta₂O₅ on visible-light photocatalytic hydrogen generation activity of Er³⁺:Y₃Al₅O₁₂/TiO₂Ta₂O₅/MoO₂ composite membrane were studied in detail. The experimental results showed that the photocatalytic hydrogen generation activity of Er³⁺:Y₃Al₅O₁₂/TiO₂Ta₂O₅/MoO₂ composite membrane heat-treated at 550 °C for 3.0 h was highest when the molar ratio of TiO₂ and Ta₂O₅ was adopted as 1.00:0.50. And that a high level photocatalytic activity can be still maintained after four cycles. In addition, a possible mechanism for the visible-light photocatalytic hydrogen generation of the Er³⁺:Y₃Al₅O₁₂/TiO₂Ta₂O₅/MoO₂ membrane was proposed based on PL spectra.     

Effect of electron beam irradiation on polydopamine and its application in polymer solar cells

Polydopamine (PDA) films were irradiated by an electron beam linear accelerator at different irradiation doses ranging from 10 to 150 kGy. The irradiated samples were characterized by Fourier transform infrared spectrometry, UV‐Vis, scanning electron microscopy, atomic force microscope, X‐ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, and thermogravimetric analysis. Changes in surface morphology, chemical structure, contact angle, frontier orbitals, and bandgap were analyzed. PDA films modified by electron beam irradiation were used in the interface design and control of polymer solar cells. Devices with the structures of ITO/ZnO/PTB7:PC₇₁BM/MoO₃/Al and ITO/PDA‐ZnO/PTB7:PC₇₁BM/MoO₃/Al were fabricated. The solar cells with a 100‐kGy electron beam‐irradiated PDA film‐modified ZnO electron transport layer had a significantly improved short circuit current density, and its efficiency reached a maximum value. The short circuit current density and power conversion efficiency reached 13.70 mA/cm² and 3.82%, respectively. Electron beam irradiation is an effective method to modify PDA, which can be used as an interface modifier in polymer solar cells.