Design and evaluation of conjugated polymers with polar side chains as electrode materials for electrochemical energy storage in aqueous electrolytes
Davide Moia, Alexander Giovannitti, Anna A. Szumska, Iuliana P. Maria, Elham Rezasoltani, Michael Sachs, Martin Schnurr, Piers R. F. Barnes, Iain McCulloch, Jenny Nelson
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Main text 16 pages including 6 figures + 49 pages of supporting information. arXiv admin note: substantial text overlap with arXiv:1711.10457
We report the development of redox-active conjugated polymers with potential application to electrochemical energy storage. Side chain engineering enables processing of the polymer electrodes from solution, stability in aqueous electrolytes and efficient transport of ionic and electronic charge carriers. We synthesized a 3,3' dialkoxybithiophene homo polymer (p type polymer) with glycol side chains and prepared naphthalene 1,4,5,8-tetracarboxylic-diimide-dialkoxybithiophene (NDI gT2) copolymers (n type polymer) with either a glycol or zwitterionic side chain on the NDI unit. For the latter, we developed a post-functionalization synthesis to attach the polar zwitterion side chains to the polymer backbone to avoid challenges of purifying polar intermediates. We demonstrate fast and reversible charging of solution processed electrodes for both the p- and n type polymers in aqueous electrolytes, without using additives or porous scaffolds and for films up to micrometers thick. We apply spectroelectrochemistry as an in operando technique to probe the state of charge of the electrodes. This reveals that thin films of the p-type polymer and zwitterion n-type polymer can be charged reversibly with up to two electronic charges per repeat unit (bipolaron formation). We combine thin films of these polymers in a two-electrode cell and demonstrate output voltages of up to 1.4 V with high redox stability. Our findings demonstrate the potential of functionalizing conjugated polymers with appropriate polar side chains to improve specific capacity, reversibility and rate capabilities of polymer electrodes in aqueous electrolytes.
Aqueous asymmetric electrochemical capacitor, with their high power density and superior cycle stability in comparison to conventional batteries, are presently considered as the most promising contender for energy storage. However, fabricating an electrode material and choosing a suitable aqueous electrolyte are vital in developing an electrochemical capacitor device with high charge storage capacity. Herein, we report a feasible method to synthesize MnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton is independe…
Synergistic Effect of Multi-Walled Carbon Nanotubes and Ladder-Type Conjugated Polymers on the Performance of N-Type Organic Electrochemical Transistors
A general Lewis acidic etching route for preparing MXenes with enhanced electrochemical performance in non-aqueous electrolyte
过渡金属的二维碳化物和氮化物，称为MXenes，是一种快速增长的二维材料家族，作为储能材料引起了人们的关注。到目前为止，MXene主要是由含Al的MAX相（其中A = Al）通过Al溶解在含F溶液中制备的，但大多数其他MAX相尚未被探索。在这里，氧化还原控制的A位蚀刻的MAX相在路易斯酸熔体中提出和验证的合成各种MXene从非常规MAX相前体与A元素Si，Zn和Ga。通过该熔融盐合成方法获得的Ti 3C 2 MXene材料的负极在1 M LiPF 6碳酸盐基电解质中提供高达738 C g-1（205 mAh g-1）的Li+存储容量，具有高倍率性能和伪电容式电化学特征。由这种熔盐合成路线制备的MXene提供了作为电化学储能应用的高倍率负极材料的机会。
In graphene based materials, the energy storage capacity is usually improved by rich porous structures with extremely high surface area. By utilizing surface corrugations, this work shows an alternative strategy to activate graphene materials for large capacitance. We demonstrate how to simply fabricate such activated graphene and how these surface structures helped to realize considerable specific capacitance (e.g., electrode capacitance of ~340 F g-1 at 5 mV s-1 and device capacitance of ~ 343 F g-1 at 1.7 A g-1) and power performance (e.g., power density of 50 and 2500 W kg-1 at the energy …
Graphene oxide finds applications in different fields of science, including energy conversion. Electrochemical reduction of graphene oxide (GO) significantly improves its conductivity. However, the kinetics of this process depends on the solvent, supporting electrolyte, pH, and numerous other factors. Most studies report the macroscopic views and ex-situ properties of reduced GO. To expand the knowledge about GO reduction, in this study, we used cyclic voltammetry (CV), simultaneous 2 points and 4 points resistance measurement (s24), conductive atomic force microscopy (AFM), and theoretical ca…
The organic electrochemical transistor (OECT) with a conjugated polymer as the active material is the elementary unit of organic bioelectronic devices. Increased functionalities, such as low power consumption, can be achieved by building complementary circuits featuring two or more OECTs. Complementary circuits commonly combine both p- and n-type transistors to reduce power draw. While p-type OECTs are readily available, n-type OECTs are less common mainly due to poor stability of the n-type active channel material in aqueous electrolyte. Additionally, an OECT based complementary circuit requi…
Chemical functionalization of nanocarbons is an important strategy to produce electrochemical systems with higher energy/power density by generating surface functional groups with additional faradaic contribution, by increasing their surface area and correspondent capacitive contribution and by improving compatibility with aqueous electrolytes and other active materials, such as pseudocapacitive metal-oxides. Here we present an electrochemical method to simultaneously swell and functionalize large electrodes consisting of fabrics of macroscopic fibers of carbon nanotubes that renders the mater…
A salt water battery with high stability and charging rates made from solution processed conjugated polymers with polar side chains
我们报道了一种中性盐水基电池，其使用p型和n型溶液处理的聚合物膜作为电池的阴极和阳极。通过在p型和n型聚合物中形成双极化子来实现电极的比容量（约30 mAh cm-3）。通过工程化乙二醇和两性离子基侧链连接到聚合物主链上，我们促进了快速离子传输通过无孔聚合物膜。这与通过共轭聚合物主链的电子电荷的有效传输相结合，允许膜在高充电和放电速率（>1000 C-速率）下保持恒定的容量。电极在电化学循环过程中也显示出良好的稳定性（在>1000次循环中容量下降小于30%）和高达1.4V的输出电压。这些具有极性侧链的半导体聚合物的性能证明了这种材料类别用于快速充电、水基电化学能量存储装置的潜力。
Electrical double layers play a key role in a variety of electrochemical systems. The mean free path of secondary electrons in aqueous solutions is on the order of a nanometer, making them suitable for probing of ultrathin electrical double layers at solid-liquid electrolyte interfaces. Employing graphene as an electron-transparent electrode in a two-electrode electrochemical system, we show that the secondary electron yield of the graphene-liquid interface depends on the ionic strength and concentration of electrolyte and applied bias at the remote counter electrode. These observations have b…
We present a theoretical and numerical scheme that enables quantifying hydrogen ingress in metals for arbitrary environments and defect geometries. This is achieved by explicitly resolving the electrochemical behaviour of the electrolyte, the hydrogen and corrosion reactions, the kinetics of surface adsorption, and hydrogen uptake, diffusion and trapping in mechanically-deforming solids. This new framework is used to produce maps that relate the absorbed hydrogen with the applied potential, specimen geometry and fluid velocity. We also present simplified versions of our generalised model, and …
The absence of piezoelectricity in silicon makes direct electro-mechanical applications of this mainstream semiconductor impossible. Integrated electrical control of the silicon mechanics, however, would open up new perspectives for on-chip actuorics. Here, we combine wafer-scale nanoporosity in single-crystalline silicon with polymerization of an artificial muscle material inside pore space to synthesize a composite that shows macroscopic electrostrain in aqueous electrolyte. The voltage-strain coupling is 3 orders of magnitude larger than the best-performing ceramics in terms of piezoelectri…
Macroscopic strain experiments revealed that Si crystals traversed by parallel, channel-like nanopores functionalized with the muscle polymer polypyrrole exhibit large and reversible electrochemo-mechanical actuation in aqueous electrolytes. On the microscopical level this system still bears open questions, as to how the electrochemical expansion and contraction of PPy acts on to np-Si pore walls and how the collective motorics of the pore array emerges from the single-nanopore behavior. An analysis of in operando X-ray diffraction experiments with micromechanical finite element simulations, b…
Although materials and processes are different from biological cells', brain mimicries led to tremendous achievements in massively parallel information processing via neuromorphic engineering. Inexistent in electronics, we describe how to emulate dendritic morphogenesis by electropolymerization in water, aiming in operando material modification for hardware learning. The systematic study of applied voltage-pulse parameters details on tuning independently morphological aspects of micrometric dendrites': as fractal number, branching degree, asymmetry, density or length. Time-lapse image processi…
Zn metal battery has been considered a promising alternative energy storage technology in renewable energy storage and grid storage. It is well-known that the surface orientation of a Zn metal anode is vital to the reversibility of a Zn metal battery. Herein, the (101)-oriented thin Zn metal anode (down to 2 μm) is electrodeposited on a Cu surface by adding dimethyl sulfoxide (DMSO) electrolyte additive in ZnSO4 aqueous solution. Scanning electron microscope (SEM) observation indicates the formation of flat terrace-like compact (101)-oriented surfaces. Insitu optical observation confirms that …
The miniaturization of energy storage units is pivotal for the development of next-generation portable electronic devices. Micro-supercapacitors (MSCs) hold a great potential to work as on-chip micro-power sources and energy storage units complementing batteries and energy harvester systems. The scalable production of supercapacitor materials with cost-effective and high-throughput processing methods is crucial for the widespread application of MSCs. Here, we report wet-jet milling exfoliation of graphite to scale-up the production of graphene as supercapacitor material. The formulation of aqu…
