Effect of electrolyte anions on the cycle life of a polymer electrode in aqueous batteries

Redox polymers are a class of high-capacity, low-cost electrode materials for electrochemical energy storage, butthe mechanisms governing their cycling stability are not well understood. Here we investigate the effect of anionson the longevity of a p-dopable polymer through comparing two aqueous zinc-based electrolytes. Galvanostaticcycling studies reveal the polymer has better capacity retention in the presence of triflate anions than that withsulfate anions. Based on electrode microstructural analysis and evolution profiles of the cell stacking pressure, theorigin of capacity decay is ascribed to mechanical fractures induced by volume change of the polymer activematerials during repeated cycling. The volume change of the polymer with the triflate anion is 61% less than thatwith the sulfate anion, resulting in fewer cracks in the electrodes. The difference is related to the different anionsolvation structures—the triflate anion has fewer solvated water molecules compared with the sulfate anion,leading to smaller volume expansion. This work highlights that anions with low solvation degree are preferablefor long-term cycling.

Carbon nanotube-hyperbranched polymer core-shell nanowires with highly accessible redox-active sites for fast-charge organic lithium batteries

Organic electrode materials are promising for lithium-ion batteries(LIBs) because of their environmental friendliness and structural diversity.However,they always suffer from limited capacity,poor cycling stability,and rate performance.Herein,hexaazatrinaphthalene-based azo-linked hyperbranched polymer(HAHP) is designed and synthesized as a cathode for LIBs.However,the densely stacked morphology lowers the chance of the active sites participating in the redox reaction.To address this issue,the singlewalled carbon nanotube(SWCNT) template is used to induce the growth of nanosized HAHP on the surface of SWCNTs.The HAHP@SWCNT nanocomposites have porous structures and highly accessible active sites.Moreover,the strong π-π interaction between HAHP and highly conductive SWCNTs effectively endows the HAHP@SWCNT nanocomposites with improved cycling stability and fast charge-discharge rates.As a result,the HAHP@SWCNT nanocomposite cathode shows a high specific capacity(320.4 mA h g^(-1)at 100 mA g^(-1)),excellent cycling stability(800 cycles;290 mA h g^(-1)at 100 mA g^(-1),capacity retained 91%) and outstanding rate performance(235 mA h g^(-1)at 2000 mA g^(-1),76% capacity retention versus 50 mA g^(-1)).This work provides a strategy to combine the macromolecular structural design and micromorphology control of electrode materials for obtaining organic polymer cathodes for high-performance LIBs.

Metal Free Polymer/Graphite Electrode-Ferricyanides Catholyte System for MFC with High Performance

A Microbial fuel cell(MFC)with metal free polymer/graphite electrodes(150 mm×150 mm)was constructed.The electrodes with flowing channels,which were different in roughness,were designed.No additional catalyst was coated on the electrode,therefore the MFC was cheaper and possessed good durability with high performance.The effect of roughness,K3Fe(CN)6 concentration and sprayed air on the performance of the constructed MFC was investigated.Results showed that the roughness of electrode can significantly affect the performance of MFC.The power density of MFC increased by 1.56 times owing to the arithmetic mean roughness which has increased by 1.41 times.With an increasing K3Fe(CN)6 concentration,the performance of MFC also improves.The MFC with K3Fe(CN)6 only(30 mM)showed the highest power density of 1260 mW/m2,which is by 21.4 times and 1.3 times higher than those of MFCs with spraying air only(59 mW/m2)and with K3Fe(CN)6+air(1005 mW/m2),respectively.This showed that the appropriate concentration of K3Fe(CN)6 can significantly improve the power density,while the air has a negative effect when it is sprayed onto K3Fe(CN)6 catholyte.A coulombic efficiency of 34.2%and an energy efficiency of 13.3%with a COD degradation rate of 73.5%were achieved with MFC using K3Fe(CN)6 only.The overpotentials of MFC were also calculated.It can be seen that both theηohmic andηconcentration were very low as compared to theηactivation,and theηconcentration can be ignored because its effect was less than 3 mV.The theoretical calculation suggested that with an increasing conversion rate of K3Fe(CN)6,the cathode potential decreased and reached 0.31 V at a conversion rate of 0.99.While the anode behaves differently for constant pH and changeable pH as the reaction progresses,which reveals that the buffer solution and removal of protons play an important role in maintaining the anode potential.

EFFECT OF STRUCTURE OF FUNCTIONAL POLYMER ACTIVE MATERIALS ON PROPERTIES OF GADOLINIUM ION SELECTIVE ELECTRODE

In this paper,the functional polymeric active materials were prepared by the grafting copolymerization and their structure and properties were studied.The results show that the structure and properties of these ac- tive materials have the relative large effects on the properties of gadolinium ion selective electrodes.

Semi-transparent polymer solar cells with all-copper nanowire electrodes

Transparent electrodes based on copper nanowires （Cu NWs） have attracted significant attention owing to their advantages including high optical transmittance, good conductivity, and excellent mechanical flexibility. However, low-cost, high-performance, and environmental friendly solar cells with all-Cu NW electrodes have not been realized until now. Herein, top and bottom transparent electrodes based on Cu NWs with low surface roughness and homogeneous conductivity are fabricated. Then, semi-transparent polymer solar cells （PSCs） with the inverted structure of polyacrylate/Cu NWs/poly（3,4- ethylenedioxythiophene）：poly（styrenesulfonate） （PEDOT：PSS） （PH1000）/Y-TiO2/ poly（3-hexylthiophene）：[6,6]-phenyl-C61-butyric acid 3,4,5-tris（octyloxy）benzyl/ PEDOT：PSS （4083）/Cu NWs/polyimide/polydimethylsiloxane are constructed; these could absorb light from both sides with a power conversion efficiency reaching 1.97% and 1.85%. Furthermore, the PSCs show an average transmittance of 42% in the visible region, which renders them suitable for some specialized applications such as power-generating windows and building-integrated photovoltaics. The indium tin oxide （ITO）- and noble metal-free PSCs could pave new pathways for fabricating cost-effective semi-transparent PSCs.

Copper nanowire-TiO2-polyacrylate composite electrodes with high conductivity and smoothness for flexible polymer solar cells

Copper nanowire （Cu NW） transparent electrodes have attracted considerable attention due to their outstanding electrical properties, flexibility and low cost. However, complicated post-treatment techniques are needed to obtain good electrical conductivity, because of the organic residues and oxide layers on the surface of the Cu NWs. In addition, commonly used methods such as thermal annealing and acid treatment often lead to nanowire damage. Herein, a TiO2 sol treatment was introduced to obtain Cu NW transparent electrodes with superb performance （13 Ω/sq @ 82% T） at room temperature within one minute. Polymer solar ceils with excellent flexibility were then fabricated on the copper nanowire- TiO2-polyacrylate composite electrode. The power conversion efficiency （PCE） of the cells based on a blend of poly（3-hexylthiophene） （P3HT） and phenyl-C61- butyric acid methyl ester （PC61BM） reached 3.11%, which was better than the control devices that used indium tin oxide （ITO）-PET electrodes, and outperforms other Cu NW based organic solar cells previously reported. The PCE of the solar cells based on Cu NW electrodes remained at 90% after 500 cycles of bending, while the PET/ITO solar cells failed after 20 and 200 cycles, with sheet resistance of 35 and 15 Ω/sq, respectively.

Carbonyl polymeric electrode materials for metal-ion batteries

Benefiting from the diversity and subjective design feasibility of molecular structure, flexibility,lightweight, molecular level controllability, resource renewability and relatively low cost, polymeric electrode materials are promising candidates for the next generation of sustainable energy resources and have attracted extensive attention for the foreseeable large scale applications. The conductive polymers have been utilized as electrode materials in the pioneer reports, which, however, have the disadvantages of low stability, low reversibility and slope voltage due to the delocalization of charges in the whole conjugated systems. The discovery of carbonyl materials aroused the interest of organic and polymeric materials for batteries again. This review presents the recent progress in carbonyl polymeric electrode materials for lithium-ion batteries, sodium-ion batteries and magnesium-ion batteries. This comprehensive review is expected to be helpful forarousing more interest of organic materials for met

Design of Neutral Carrier for Solvent Polymeric Membrane Iodide Electrode With High Selectivity

Anion-selective electrodes based on dissociated ion-exchangers such as lipophilicquaternary ammonium or phosphonium species always display classical Hofmeister be-havior in the following order: ClO4-】SCN-】I-】Br-】NO2-】Cl-】SO42-.A new sol-vent polymeric membrane electrode based on Schiff base complexes of Co（Ⅱ）[Co（Ⅱ）S]and showing excellent selectivity toward iodide ion is for the first time prepared inour work. The resulting electrodes exhibit fairly low detection limits andpotentiometric anion-selectivity sequences deviated from the Hofmeister pattern.Bis（salicylaldehyde） ethylenediiminecobalt（Ⅱ） [Co（Ⅱ）（salen）], bis（salicylaldehyde）-phenyldiiminecobalt（Ⅱ） [Co（Ⅱ）（salophen）],

Efficiency of terahertz detection in electro-optic polymer sensors with interdigitated coplanar electrodes

We discuss the efficiency of an electro-optic （EO） polymer sensor with interdigitated coplanar electrodes. The developed EO sensor is used to detect terahertz radiation via EO sampling. Results show that the sensor improves more significantly detection sensitivity than does a sensor with sandwich configurations.

Study on electrode process of myoglobin at a polymerized Toluidine Blue film electrode

This paper reports the use of an electrochemically polymerized Toluidine Blue (TB) film electrode.The film on platinum electrode surface was analyzed with ESCA.The heterogeneous electron transfer processes of myoglobin at the polymerized TB film electrode have been investigated using in situ UV-visible spectroelectrochemistry.The formal potential(E°′)and electron transfer number(n)of myoglobin were calculated as E°′=0.045 V(vs.NHE)and n=0.99.The exhaustive reduction and oxidation electrolyses are achieved in 130 s and 110 s respectively,during a potential step between-0.4 V and+0.4 V.A formal heterogeneous electron transfer rate constant(ksh)of 1.09× 10^(-4) cm/s and a transfer coefficient(α)of 0.47 were obtained by cyclic voltabsorptometry,which indicated that myoglobin underwent a quasi-reversible electrode process at the polymerized TB film electrode.

Regulated CO adsorption by the electrode with OH^(-) repulsive property for enhancing C–C coupling

Electrochemical CO_(2) reduction driven by renewable electricity is one of the promising strategies to store sus-tainable energy as fuels.However,the selectivity of value-added multi-carbon products remains poor for further application of this process.Here,we regulate CO adsorption by forming a Nafion layer on the copper(Cu)electrode that is repulsive to OH^(-),contributing to enhanced selectivity of CO_(2) reduction to C_(2) products with the suppression of C 1 products.The operando Raman spectroscopy indicates that the local OH^(-)would adsorb on part of active sites and decrease the adsorption of CO.Therefore,the electrode with repulsive to OH^(-)can adjust the concentration of OH^(-),leading to the increased adsorption of CO and enhanced C–C coupling.This work shows that electrode design could be an effective strategy for improving the selectivity of CO_(2) reduction to multi-carbon products.

Highly ordered graphene architectures by duplicating melamine sponges as a three-dimensional deformation- tolerant electrode

In this study, macroscopic graphene-wrapped melamine foams （MF-G） were fabricated by an MF-templated layer-by-layer （LBL） assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole （PPy） was then attached and uniformly coated on MF-G, resulting in a well-defined core- double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g-1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge- discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression-release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.