Electroactive polymeric nanofibrous composite to drive in situ construction of lithiophilic SEI for stable lithium metal anodes

Uncontrolled lithium dendrite growth hinders the practical application of lithium metal batteries(LMBs).Herein,we report a novel Li^(+) flux distributor achieved by placing an electroactive polyvinylidene fluoride/polymethyl methacrylate(PVDF/PMMA)composite nanofiber interlayer on a current collector,inducing uniform lithium deposition to mitigate the dendrite problem.Specifically,the released PMMA reacts with Liþto form abundant C–O–Li bonds and generate in situ a stable lithiophilic PMMA-Li solid electrolyte interphase layer.Theoretical calculations reveal that polar C–F groups in the PVDF framework and lithiophilic PMMA-Li provide homo-dispersed Li^(+) migration pathways with low energy barriers.Consequently,uniform Li nucleation is achieved at the molecular level,resulting in ultrahigh cycling stability with dendrite-free Li deposition at 5 mA cm^(-2) and 5 mAh cm^(-2)for over 500 h.The PVDF/PMMA||Li||LiFePO_(4)(LFP)full cell presents an increased rate capacity of 110 mAh g^(-1) at 10 C.In addition,a soft-package battery demonstrates a high energy density of 289 Wh kg^(-1).This work provides a facile design for stable lithium metal anodes to promote the practical use of LMBs and other alkali metal batteries.

Printed unmanned aerial vehicles using paper-based electroactive polymer actuators and organic ion gel transistors

We combined lightweight and mechanically flexible printed transistors and actuators with a paper unmanned aerial vehicle(UAV)glider prototype to demonstrate electrically controlled glide path modification in a lightweight,disposable UAV system.The integration of lightweight and mechanically flexible electronics that is offered by printed electronics is uniquely attractive in this regard because it enables flight control in an inexpensive,disposable,and easily integrated system.Here,we demonstrate electroactive polymer(EAP)actuators that are directly printed into paper that act as steering elements for low cost,lightweight paper UAVs.We drive these actuators by using ion gel-gated organic thin film transistors(OTFTs)that are ideally suited as drive transistors for these actuators in terms of drive current and frequency requirements.By using a printing-based fabrication process on a paper glider,we are able to deliver an attractive path to the realization of inexpensive UAVs for ubiquitous sensing and monitoring flight applications.

Influence of conductive network composite structure on the electromechanical performance of ionic electroactive polymer actuators

The influence of the nanostructure of the conductive network composite(CNC)on the performance of ionic electroactive polymer(IEAP)actuators has been examined in detail.We have studied IEAP actuators consisting of CNCs with different volume densities of gold nanoparticles(AuNPs)and the polymer network.Varying the concentration of AuNPs in CNC thin films was used as a means to control the CNC-ion interfacial area and the electrical resistance of the CNC,with minimum effect on the mechanical properties of the actuator.Increasing the interfacial area and reducing the resistance,while maintaining porosity of the composite,provide means for generating motion of more ions into the CNC at a significantly shorter time,which results in generation of strain at a faster rate.We have demonstrated that cationic strain in actuators with denser CNCs is improved by more than 460%.Denser CNC structures have larger interfacial areas,which results in attraction/repulsion of more ions in a shorter time,thus generation of a larger mechanical strain at a faster rate.Also,time-dependent response to a square-wave voltage was improved by increasing the AuNP concentration in the CNC.Under 0.1 Hz frequency,the cationic strain was increased by 64%when the AuNP concentration was increased from 4 to 20 ppm.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅲ. Effect of the Polymer Solvents

The diffusion coefficients(Dapp) and the heterogeneous electron transfer rate constants(ks)for ferrocene in several polymer solvents were determined by using steady-stae voltammetry. Thetemperature dependence of the two parameters indicates Arrhenius behavior. The polymer solventeffects on diffusion and electron transfer dynamics of ferrocene were discussed

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅰ. Effect of the Nature of Electroactive Solutes

The diffusion coefficients(Dapp) and the heterogeneous electron-transfer rate constants(ks)for ferrocene and its seven derivatives in MPEG/LiClO4 electrolyte were determined by using steadystate voltammetry. The two parameters increase with increasing temperature, indicating Arrhenius behavior. The effects of the nature of electroactive solute molecules on Dapp, ks, and the half-wave potentials(E1/2) are discussed.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅱ. Effect of the Ionic Size of Supporting Electrolytes

The ditheion coefficients(Dapp) and the heterogeneous electron-transfer rate constan(ks)for ferrocene in MPEG/salt electrolytes were determined by using Steady-stae voltammetry. The temperature dependence of the two parameters obeys the Arrhenius equstion. The effect of the ionic size of sir supporting electrolytes on diffusion and electron transfer dynamics of fermcene was discussed

Dielectric elastomer artificial muscle materials advancement and soft robotic applications

Conventional robotic systems are built with rigid materials to deal with large forces and predetermined processes.Soft robotics,however,is an emerging field seeking to develop adaptable robots that can perform tasks in unpredictable environments and biocompatible devices that close the gap between humans and machines.Dielectric elastomers(DEs)have emerged as a soft actuation technology that imitates the properties and performance of natural muscles,making them an attractive material choice for soft robotics.However,conventional DE materials suffer from electromechanical instability(EMI),which reduces their performance and limits their applications in soft robotics.This review discusses key innovations in DE artificial muscles from a material standpoint,followed by a survey on their representative demonstrations of soft robotics.Specifically,we introduce modifications of DE materials that enable large strains,fast responses,and high energy densities by suppressing EMI.Additionally,we examine materials that allow variable stiffness and self‐healing abilities in DE actuators.Finally,we review dielectric elastomer actuator(DEA)applications in soft robotics in four categories,including automation,manipulation,locomotion,and human interaction.

Improving electromechanical output of IPMC by high surface area Pd-Pt electrodes and tailored ionomer membrane thickness

In this study,we attempt to improve the electromechanical performance of ionic polymer–metal composites(IPMCs)by developing high surface area Pd-Pt electrodes and tailoring the ionomer membrane thickness.With proper electroless plating techniques,a high dispersion of palladium particles is achieved deep in the ionomer membrane,thereby increasing notably the interfacial surface area of electrodes.The membrane thickness is increased using 0.5 and 1 mm thick ionomer films.For comparison,IPMCs with the same ionomer membranes,but conventional Pt electrodes,are also prepared and studied.The electromechanical,mechanoelectrical,electrochemical and mechanical properties of different IPMCs are characterized and discussed.Scanning electron microscopy-energy dispersive X-ray(SEM-EDS)is used to investigate the distribution of deposited electrode metals in the cross section of Pd-Pt IPMCs.Our experiments demonstrate that IPMCs assembled with millimeter thick ionomer membranes and newly developed Pd-Pt electrodes are superior in mechanoelectrical transduction,and show significantly higher blocking force compared to conventional type of IPMCs.The blocking forces of more than 0.3 N were measured at 4V DC input,exceeding the force output of typical Nafion®117-based Pt IPMCs more than two orders of magnitude.The newly designed Pd-Pt IPMCs can be useful in more demanding applications,e.g.,in biomimetic underwater robotics,where high stress and drag forces are encountered.

Performance of Ion-gel Actuator Containing Ionic Liquids

1 Results Electroactive polymers (EAPs) driven by transducing electric energy into mechanical energy have been the subjects of recent interest[1]."Ionic liquids",consisting entirely of cation and anion,have characteristic features such as negligible volatility,non-flammability,thermal and chemical stability,and high ionic conductivity.We proposed an EAP actuator utilizing ion-gels[2-3],which consist of ionic liquids and polymers,sandwiching with two carbon material sheets as shown in Fig.1.This electrol...

Polyurethane-based Actuators with Various Polyols

This study dealt with the electrostrictive responses of polyurethane （PU） actuators with different microphase separation structure, which was a promising candidate for a material used in polymer actuators. In order to construct PUs with different higher-order structure, PUs with various types of polyol were synthesized： poly（neopentyl glycol adipate） （PNAD）, poly（tetramethylene glycol） （PTMG）, and poly（dimethyl siloxnae） （PDMS）. Synthesized PU was characterized by Fourier transform-infrared （FT-IR） spectroscopy and gel per- meation chromatography （GPC）. Thermal analysis and mechanical properties of PU films were carried out with differential scanning calorimetry （DSC） and UTM （universal testing machine）, respectively. And PU actuator was formed in a type of monomorph, which was made by carbon black electrodes on the both surfaces of PU film by spin coating method. Actuation behavior was mainly influenced on microphase separation struc- ture and mechanical property of PU. In result, PU actuator with PNAD, polyester urethane, had the largest field-induced displacement.

Modeling the Damage and Self-healing Behaviors of Plasticized PVC Gels

Plasticized polyvinyl chloride(PVC)gel is a type of electroactive polymers,which has potentials to be applied as soft actuators.However,few studies have been performed to investigate the mechanical responses of PVC gels in cyclic loading conditions.In this work,we combined experiments and theory to characterize the mechanical responses of two plasticized PVC gels.The gels were subjected to different types of loading-unloading-reloading cycles.The experimental results showed that the plasticized PVC gels exhibited stress softening response(the Mullins effect)in the cyclic tests.Meanwhile,the gels regained some strength after annealing at room temperature for several hours,indicating the self-healing ability of gels.We further extended the eight-chain model with incorporation of the chain dissociation and reassociation mechanism.The developed constitutive model is able to reproduce the Mullins effect and the recovery of the Mullins effect observed in the experiments.Our results clearly show that understanding the complex mechanical response is crucial for the applications of plasticized PVC gels.