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Strong interest from researchers and industry is accelerating development of flexible energy storage technologies for future flexible devices. It is critical to consider the environmental perspective in early development of new emerging technologies. In this study, cradle-to-factory gate prospective life cycle assessment (LCA) was performed on production of an all-organic battery with conductive redox polymers as electrode material. To gain a better understanding of the environmental performance of the all-organic battery, a flexible lithium-ion (Li-ion) battery with lithium titanate oxide and lithium cobalt oxide as electrode active materials was modeled as reference. Main environmental impacts of the all-organic battery were attributable to anode and cathode production, with electrode backbones being the main contributors. Solvents, catalysts, waste treatment, energy, and bromine were key individual contributors. Comparison with the flexible Li-ion battery indicated inferior environmental performance of the all-organic battery due to its relatively low specific energy (Wh/kg) and large amount of materials needed for production of its electrode backbones. Sensitivity analysis showed that changing scaling-up parameters and the production route of 3,4-ethylenedioxythiophene (a precursor of electrode backbones) strongly influenced the results. In order to lower the environmental impacts of the all-organic battery, future research should focus on designing a short production chain with lower material inputs of electrode backbones, increasing battery cycle life, and improving the specific energy of the battery. In addition, relevant recommendations were provided for prospective LCAs of upscaled systems. [Display omitted] • Prospective LCA was performed on an all-organic battery and flexible Li-ion battery. • Flexible Li-ion battery shows better environmental performance. • Environmental hotspots and improvement areas for an all-organic battery are listed. • Practical recommendations on LCA in emerging technologies are provided. [ABSTRACT FROM AUTHOR]

Molecular catalysts for water oxidation and other electrochemical transformations have been a focus of significant research over recent decades. Among these, α-[Fe(mcp)L 2 ] complexes stand out as one of the most active non-heme iron-based molecular catalyst for water oxidation. This study investigates how the Fe(II)/Fe(III) redox potential of these catalysts varies with the identity of their labile ligands (L). Using cyclic voltammetry and complementary spectroscopic techniques (UV/Vis, 1H NMR), we examined how ligands bind to the metal centre. Systematic variation of the labile ligand (L) demonstrated that the catalyst's redox potential in acetonitrile solution strongly depends on ligand identity. By introducing stoichiometric amounts of different anions to the electrolyte, the redox potential was tuned across a 1.5 V potential window. In aqueous solutions, the redox potential depended on both pH and electrolyte anion identity. These dependencies were successfully fitted to a thermodynamic model that was obtained by extending the typical proton-coupled electron transfer square scheme into a cube scheme that incorporates anion binding. The equation derived from this model provides valuable insights into the ligand-binding dynamics at the iron centre under diverse conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Quinone potential tuned by cycling ion and carbonyl group in ortho- or para-position. • Cycling of metal ions and protons. • Quinones compatible with sodium, potassium, magnesium and calcium cations. • Higher redox potential and charge uptake give higher stabilizing effect on quinone. Quinones exhibit considerable promise as active components in energy storage applications, owing to their high theoretical storage capacity, well-defined redox potentials, rapid reaction kinetics, structural diversity, and proficiency in cycling both protons and metal ions. In this study, six quinone derivatives underwent comprehensive electrochemical and computational analyses using TBA+, H +, Li+, K +, Na+, Ca2+, and Mg2+-based electrolytes, aiming to uncover novel cycling chemistries with organic materials. Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV) elucidated the widely recognized 2H+/2e- redox process during proton cycling, as well as the two-step 1e- redox process in the presence of other cycling ions. Additionally, it was established that the quinone formal redox potential for different cycling chemistries followed the sequence TBA+ < K + < Na+ < Li+ < H +, and cycling of the divalent cations resulted in potentials within the same range as those observed for proton cycling. DFT calculations provided insights into how cycling ions influenced the quinone formal redox potential, attributing it to the cation's ability to accommodate a portion of the bisolate anion charge upon reduction. Cations inducing a higher quinone formal redox potential and accommodating a larger fraction of the negative charge demonstrated a greater stabilizing effect on the reduced state. This stabilizing effect exhibited a strong correlation with the ionization energies of the respective cations. [ABSTRACT FROM AUTHOR]

Electrodes based on organic matter operating in aqueous electrolytes enable new approaches and technologies for assembling and utilizing batteries that are difficult to achieve with traditional electrode materials. Here, we report how thiophene‐based trimeric structures with naphthoquinone or hydroquinone redox‐active pendent groups can be processed in solution, deposited, dried and subsequently polymerized in solid state to form conductive (redox) polymer layers without any additives. Such post‐deposition polymerization offers efficient use of material, high mass loading (up to 10 mg cm−2) and good flexibility in the choice of substrate and coating method. By employing these materials as anode and cathode in an acidic aqueous electrolyte a rocking‐chair proton battery is built. The battery shows good cycling stability (85 % after 500 cycles), withstands rapid charging, with full capacity (60 mAh g−1) reached within 100 seconds, allows for direct integration with photovoltaics, and retains its favorable characteristics even at −24 °C. [ABSTRACT FROM AUTHOR]

• Immobilization of molecular electrocatalysts into heterogeneous environment. • Conducting polymers as successful platform immobilization technique for porphyrins. • Coordination geometry of central metal ion determines electron transport pathway. • Immobilization method affects electrocatalytic abilities of molecules. Molecular catalysts are attracting interest as drivers of redox reactions for sustainable applications. Through systematic molecular design, they could be engineered to have high selectivity and activity towards a multitude of catalytic reactions. However, as long as they are used in homogeneous setups, they will suffer from inconvenient energy supply, inefficient charge transport and difficulty in separation from reaction products. To be relevant for industrial applications, molecular catalysts must be bound to solid materials in direct contact with the energy source. In this regard, conducting polymers are particularly interesting, as they provide a straightforward means of both surface immobilization and charge transport. In this work, we synthesize and characterize three different metalloporphyrin-functionalized conducting polymers and apply them to catalysis of the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR). We show that incorporation of porphyrins into conducting polymers is a reliable immobilization method, that the properties of both the porphyrin units and the polymer backbone are preserved in all systems, and that the polymers provide efficient charge transport to and from the catalytic centers. Nevertheless, we also find that the polymers are negatively affected by intermediates formed during the HER and the ORR. We conclude that the choice of immobilization method has a large impact on the quality of the molecular catalyst, and that the effect of the catalytic cycle on the immobilization matrix must be considered in the molecular design process. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium-ion technologies show great promise to meet the demands that the transition towards renewable energy sources and the electrification of the transport sector put forward. However, concerns regarding lithium-ion batteries, including limited material resources, high energy consumption during production, and flammable electrolytes, necessitate research on alternative technologies for electrochemical energy storage. Organic materials derived from abundant building blocks and with tunable properties, together with water based electrolytes, could provide safe, inexpensive and sustainable alternatives. In this study, two conducting redox polymers based on poly(3,4-ethylenedioxythiophene) (PEDOT) and a hydroquinone pendant group have been synthesized and characterized in an acidic aqueous electrolyte. The polymers were characterized with regards to kinetics, pH dependence, and mass changes during oxidation and reduction, as well as their conductance. Both polymers show redox matching, i.e. the quinone redox reaction occurs within the potential region where the polymer is conducting, and fast redox conversion that involves proton cycling during pendant group redox conversion. These properties make the presented materials promising candidates as electrode materials for water based all-organic batteries. [ABSTRACT FROM AUTHOR]

The combination of high capacity redox active pendent groups and conducting polymers, realized in conducting redox polymers (CRPs), provides materials with high charge storage capacity that are electronically conducting which makes CRPs attractive for electrical energy storage applications. In this report, six polythiophene and poly(3,4-ethylenedioxythiophene)(PEDOT)-based CRPs with a diethyl terephthalate unit covalently bound to the polymer chain by various linkers have been synthesized and characterized electrochemically. The effects of the choice of polymer backbone and of the nature of the link on the electrochemistry, and in particular the cycling stability of these polymers, are discussed. All CRPs show both the doping of the polymer backbone as well as the redox behavior of the pendent groups and the redox potential of the pendent groups in the CRPs is close to that of corresponding monomer, indicating insignificant interaction between the pendant and the polymer backbone. While all CRPs show various degrees of charge decay upon electrochemical redox conversion, the PEDOT-based CRPs show significantly improved stability compared to the polythiophene counterparts. Moreover, we show that by the right choice of link the cycling stability of diethyl terephthalate substituted PEDOT-based CRPs can be significantly improved. [ABSTRACT FROM AUTHOR]

In this report we present the synthesis and characterization of two conducting redox polymers (CRPs) with polythiophene backbone and diethyl terephthalate pendant groups for the use as anode materials in secondary batteries. The materials show excellent rate capability allowing 30 μm layers to be fully converted within seconds without the use of conductive additives. The high rate capability is traced to the open morphology of the materials that allows for fast ion transport, and to the mediation of electrons through the conducting polymer (CP) backbone. The requirements for the latter are i) that the redox chemistry of the pendant groups and the CP backbone overlaps and ii) that the CP conductivity is not compromised by the presence of the pendant groups. In the CRPs presented herein both these requirements are met and this is thus the first report on successful combination of the redox chemistry of organic redox molecules with the n-doping of conducting polymers. [ABSTRACT FROM AUTHOR]

In this work, we aim to resolve different diffusion processes in polypyrrole/cellulose composites using a combination of impedance spectroscopy and finite element simulations. The computational model involves a coupled system of Ohm's law and Fickian diffusion to model electrode kinetics, non-linear boundary interactions at the electrode interfaces and ion transport inside the porous electrodes, thereby generating the impedance response. Composite electrodes are prepared via chemical polymerization of pyrrole on the surface of a nanocellulose fiber matrix, and the electrochemical properties are investigated experimentally using cyclic voltammetry, impedance spectroscopy and galvanostatic cycling. It is demonstrated that the onset frequency of the capacitive (or pseudocapacitive) process depends on the counter ion electrolyte diffusion, which is modulated by adding different amounts of sucrose to the aqueous electrolyte solution. Consequently, the electrochemical properties can be controlled by diffusion processes occurring at different length scales, and the critical diffusion processes can be resolved. It is shown that under normal operating conditions, the limiting process for charge transport in the device is diffusion within the electrolyte filled pores of the composite electrode. [ABSTRACT FROM AUTHOR]

Polypyrrole functionalized with redox active pendant groups constitutes a so called conducting redox polymer, and functions both as a conducting polymer and as a redox polymer. The electrochemical response reveals capacitive charging of the conducting backbone as well as redox cycling of the pendant groups. While the backbone provides an electrically conducting matrix for fast electron transport through the material, the pendant groups offer a large charge storage capacity, much greater than that of polypyrrole itself. We have investigated such polypyrrole-hydroquinone conducting redox polymers, with focus on their in situ conductivity during electrochemical cycling, in order to understand the charge transport mechanisms in this type of system. The most notable feature is that oxidation of the pendant groups leads to a large decrease in the polymer conductivity. The causes of this phenomenon are discussed, as well as the rate limitations of fast redox cycling of the polymer, which are investigated through a combination of bipotentiostat cyclic voltammetry and potential steps of polymer films on interdigitated array electrodes. [ABSTRACT FROM AUTHOR]

• Porphyrin-functionalized trimer electropolymerized onto current collector. • Individual properties of conducting polymer/porphyrin pendants well preserved. • Conducting polymer improves charge transport to porphyrins/catalytic units. • Two superimposed charge transport mechanisms. • Tunable system ready for heterogeneous electrocatalysis of redox reactions. The climate crisis has created a demand for molecular catalysts that can drive redox reactions for production of sustainable fuels. To this end, we present the design, synthesis and characterization of a conducting polymer backbone functionalized with free base porphyrin pendant groups. Combining intrinsic charge transport with catalytic prospect, this system offers possibilities of molecular heterogeneous electrocatalysis with straightforward energy supply and product extraction. Using cyclic voltammetry and spectroelectrochemistry, we show that the polymerized system is stable, and that the properties of the polymer and the porphyrins are independently preserved. With in-situ conductance measurements, we demonstrate that polaronic charge transport through the polymer backbone is superimposed by redox conductivity through the porphyrin pendant groups. These results suggest that our system is a reliable fundamental structure suitable for tuning towards heterogeneous catalysis of redox reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

Organic batteries are emerging as a potential sustainable power source for future flexible devices. Using life cycle assessment, this study analyzed the environmental impacts from the synthesis process for an all-organic battery with conducting redox polymers as active materials for electrodes. Synthesis steps were modeled and analyzed in detail, based on actual laboratory processes data for electrodes, and industrial data for other battery components. Complete and transparent inventory data are presented and can be used in future environmental assessments. The organic battery studied is still at an early development stage, so environmental hotspots and potential improvements in the synthesis processes were examined. For selected environmental impact categories, the life cycle assessment results showed that synthesis of cathode backbone was the major contributor (47–63%) to the environmental impacts of the all-organic battery cell among different synthesis stages, because of a long synthesis route associated with high solvent usage. Solvents (e.g. , dichloromethane), catalysts (e.g. , copper oxide, Pd(PPh 3) 4), zinc, and waste treatment processes were important single contributors to the total impacts. The results reveal significant potential for improvement by optimizing the amount of solvents needed to synthesize battery electrodes. Changing treatment methods for laboratory waste solvents can also strongly influence the results. • LCA of an emerging technology at lab scale: an all-organic battery. • Complete and transparent life cycle inventory is disclosed. • Solvents contribute most to the environmental impact. • Changing the waste solvent treatment method strongly affects the results. [ABSTRACT FROM AUTHOR]

Organic carbonyl compounds have been considered as promising alternatives to traditional inorganic battery materials due to their low-cost, sustainability and structural diversity. The development of carbonyl compounds as energy storage materials is, however, hampered by dissolution as well as by the low electronic conductivity of these materials. Herein a conducting redox polymer concept is employed where the carbonyl group is functionalized onto a conducting polymer. The utilization of a conducting polymer prevents the dissolution and provides electron transport pathways to support the carbonyl group redox reaction. A high potential quinizarin (Qz) is used as capacity-carrying group. It is functionalized onto a thiophene-based trimer unit which is polymerized through a post-deposition polymerization method. In the resulting material, Qz is redox-matched with the conducting polymer backbone and exhibits two reversible 1e/1Li+ redox processes at 3.1 and 3.4 V vs. Li+/0, respectively. Together with a lithium metal anode, a battery cell with an average discharge voltage of 3.3 V, a discharge capacity of 65 mAh/g at 1.5 C and a capacity retention of 74% after 500 cycles is assembled. [ABSTRACT FROM AUTHOR]

In this study, conducting redox polymers (CRPs), which consist of a polypyrrole conducting polymer backbone with attached quinone pendant groups, have been explored as electrode materials for organic batteries. A modular organic synthetic approach is presented that allows the assembly of pyrrole and quinone units into quinone-pyrrole dyads and modifying the dyads by varying the substitution pattern on the quinone moiety. These dyad monomers were copolymerized electrochemically with pyrrole to yield the CRPs with quinone formal potentials varying within a 0.6 V range. With access to CRP materials with tunable quinone formal potentials an all-organic water-based battery was constructed by choosing CRPs with different quinone potentials as anode and cathode material. Galvanostatic charge-discharge of the cell showed that the cell potentials coincided well with the difference in redox potential between the quinone substituents used in the anode and cathode CRP. [ABSTRACT FROM AUTHOR]

• We have used a conjugated redox polymer (CRP) in ion-selective electrodes. • The CRP was applied for the first time as a solid contact. • It has a PEDOT backbone with covalently bound hydroquinone (HQ) pendant groups. • PEDOT-HQ has superior redox capacitance to unsubstituted PEDOT due to the HQ groups. • The covalent attachment prevents the leaching of the HQ pendant groups. We have used for the first time a conjugated redox polymer with hydroquinone (HQ) pendant groups covalently attached to the poly(3,4-ethylenedioxythiophene) (PEDOT) backbone as the solid contact (SC) in plasticized poly(vinyl chloride) (PVC) based K+-selective electrodes (K-SCISE). Redox couples are one of the simplest ways to precisely adjust the standard potential (E °) of the SCISEs, but usually the initially high E ° reproducibility is lost quite quickly due to leaching out of non-covalently bound redox molecules from the SCISE. In PEDOT-HQ, the covalently attached HQ groups prevent the leaching and simultaneously allow additional charge storage in PEDOT-HQ that is ca. 25–30 times higher than for unsubstituted PEDOT. Before the ion-selective membrane (ISM) deposition, we controlled the potential of the SC with high reproducibility (±0.4 mV, n = 5) by pre-polarization in a mixture of acetonitrile containing potassium tetrakis(pentafluorophenyl)borate and perchloric acid as proton source. Pre-polarization of the SC close to the formal potential where the redox buffer capacity is highest gave the best potential reproducibility. However, after the ISM deposition, the K-SCISEs showed in the best case an E ° reproducibility of ±2.8 mV (n = 5). Chronopotentiometric measurements reveal that only a minor fraction of the very high redox capacitance of PEDOT-HQ can be utilized for the ion-to-electron transduction beneath the ISM. The influence of this shortcoming on the E ° reproducibility of the SCISEs has been underestimated for most SC materials. Modification of the commonly used PVC-ISM formulations to allow faster ion transfer at the SC/ISM interface could be one way of overcoming the disadvantage. [ABSTRACT FROM AUTHOR]

Li-ion batteries (LIBs) raise safety and environmental concerns, which mostly arise from their toxic and flammable electrolytes and the extraction of limited material resources by mining. Recently, water-in-salt electrolytes (WiSEs), in which a large amount of lithium salt is dissolved in water, have been proposed to allow for assembling safe and high-voltage (>3.0 V) aqueous LIBs. In addition, organic materials derived from abundant building blocks and their tunable properties could provide safe and sustainable replacements for inorganic cathode materials. In the current work, the electrochemical properties of a conducting redox polymer based on poly(3,4-ethylenedioxythiophene) (PEDOT) with hydroquinone (HQ) pendant groups have been characterized in WiSEs. The quinone redox reaction occurs within the potential region where the polymer is conducting, and fast redox conversion that involves lithium cycling during pendant group redox conversion was observed. These properties make conducting redox polymers promising candidates as cathode-active materials for safe and high-energy aqueous LIBs. An organic-based aqueous LIB, with a HQ-PEDOT as a cathode, Li 4 Ti 5 O 12 (LTO) as an anode, and ca. 15 m lithium bis(trifluoromethanesulfonyl)imide water/dimethyl carbonate (DMC) as electrolyte, yielded an output voltage of 1.35 V and high rate capabilities up to 500C. Unlabelled Image • A hybrid organic lithium ion battery using a water-in-salt electrolyte (WISE) • Electrochemical characterization of a conducting redox polymer (CRP) in WiSEs. • The battery yielded a voltage of 1.35 V and high rate capabilities, up to 500C. • Quinones can be forced to cycle lithium in water electrolyte. [ABSTRACT FROM AUTHOR]

Rechargeable batteries that use redox-active organic compounds are currently considered an energy storage technology for the future. Functionalizing redox-active groups onto conducting polymers to make conducting redox polymers (CRPs) can effectively solve the low conductivity and dissolution problems of redox-active compounds. Here, we employ a solution-processable postdeposition polymerization (PDP) method, where the rearrangements ensured by partial dissolution of intermediated trimer during polymerization were found significant to produce high-performance CRPs. We show that quinizarin (Qz)- and naphthoquinone (NQ)-based CRPs can reach their theoretical capacity through optimization of the polymerization conditions. Combining the two CRPs, with the Qz-CRP as a cathode, the NQ-CRP as an anode, and a protic ionic liquid electrolyte, yields a 0.8 V proton rocking-chair battery. The conducting additive-free all-organic proton battery exhibits a capacity of 62 mAh/g and a capacity retention of 80% after 500 cycles using rapid potentiostatic charging and galvanostatic discharge at 4.5 C.

Utilizing organic redox-active materials as electrodes is a promising strategy to enable innovative battery designs with low environmental footprint during production, which can be hard to achieve with traditional inorganic materials. Most electrode compositions, organic or inorganic, require binders for adhesion and conducting additives to enable charge transfer through the electrode, in addition to the redox-active material. Depending on the redox-active material, many types and combinations of binders and conducting additives have been considered. We designed a conducting polymer (CP), with a soluble, trimeric unit based on 3,4-ethylenedioxythiophene (E) and 3,4-propylenedioxythiophene (P) as the repeat unit, acting as a combined binder and conducting additive. While CPs as additives have been explored earlier, in the current work, the use of a trimeric precursor enables solution processing together with the organic redox-active material. To evaluate this concept, the CP was blended with a redox polymer (RP), which contained a naphthoquinone (NQ) redox group at different ratios. The highest capacity for the total weight of the CP/RP electrode was 77 mAh/g at 1 C in the case of 30% EPE and 70% naphthoquinone-substituted poly(allylamine) (PNQ), which is 70% of the theoretical capacity given by the RP in the electrode. We further used this electrode in an aqueous battery, with a MnSO 4 cathode. The battery displayed a voltage of 0.95 V, retaining 93% of the initial capacity even after 500 cycles at 1 C. The strategy of using a solution-processable CP precursor opens up for new organic battery designs and facile evaluation of RPs in such.

Organic materials receive increasing attention as environmentally benign and sustainable electrode-active materials. We present a conducting redox polymer (CRP) based on poly(3,4-ethylenedioxythiophene) with naphthoquinone pendant group, which is formed from a stable suspension of a trimeric precursor and an oxoammonium cation as oxidant. This suspension allows us to easily coat the polymer onto a current collector, opening up use of roll-to-roll processing or ink-jet printing for electrode preparation. The CRP showed a full capacity of 76 mAh g -1 even at a high C rate of 100 C in acidic aqueous electrolyte. These properties make the CRP a promising candidate as anode-active material; a polymer-air secondary battery was fabricated with the CRP as anode, a conventional Pt/C catalyst as cathode, and sulfuric acid aqueous solution as electrolyte. This battery yielded a discharge voltage of 0.50 V and showed good cycling stability with 97 % capacity retention after 100 cycles and high rate capabilities up to 20 C., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite a large number of publications describing biosensors based on electrochemical impedance spectroscopy (EIS), little attention has been paid to the stability and reproducibility issues of the sensor interfaces. In this work, the stability and reproducibility of faradaic EIS analyses on the aptamer/mercaptohexanol (MCH) self-assembled monolayer (SAM)-functionalized gold surfaces in ferri- and ferrocyanide solution were systematically evaluated prior to and after the aptamer-probe DNA hybridization. It is shown that the EIS data exhibited significant drift, and this significantly affected the reproducibility of the EIS signal of the hybridization. As a result, no significant difference between the charge transfer resistance ( R CT ) changes induced by the aptamer-target DNA hybridization and that caused by the drift could be identified. A conditioning of the electrode in the measurement solution for more than 12 h was required to reach a stable R CT baseline prior to the aptamer-probe DNA hybridization. The monitored drift in R CT and double layer capacitance during the conditioning suggests that the MCH SAM on the gold surface reorganized to a thinner but more closely packed layer. We also observed that the hot binding buffer used in the following aptamer-probe DNA hybridization process could induce additional MCH and aptamer reorganization, and thus further drift in R CT . As a result, the R CT change caused by the aptamer-probe DNA hybridization was less than that caused by the hot binding buffer (blank control experiment). Therefore, it is suggested that the use of high temperature in the EIS measurement should be carefully evaluated or avoided. This work provides practical guidelines for the EIS measurements. Moreover, because SAM-functionalized gold electrodes are widely used in biosensors, for example, DNA sensors, an improved understanding of the origin of the observed drift is very important for the development of well-functioning and reproducible biosensors.

In the water-oxidizing reactions of photosystem II (PSII), a tyrosine residue plays a key part as an intermediate electron-transfer reactant between the primary donor chlorophylls (the pigment P(680)) and the water-oxidizing Mn cluster. The tyrosine is deprotonated upon oxidation, and the coupling between the proton reaction and electron transfer is of great mechanistic importance for the understanding of the water-oxidation mechanism. Within a programme on artificial photosynthesis, we have made and studied the proton-coupled tyrosine oxidation in a model system and been able to draw mechanistic conclusions that we use to interpret the analogous reactions in PSII.