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An affordable, safe, and scalable battery system is presented, which uses organic polymers as the charge-storage material in combination with inexpensive dialysis membranes and an aqueous sodium chloride solution as the electrolyte. An affordable redox-flow battery Redox-flow batteries are seen as a promising technology for storing energy from renewable resources: they are rechargeable and are easily adapted to larger scales simply by increasing the volume of the liquid electrolytes. Most redox-flow batteries are based on metals, usually vanadium, in acidic media, and charge generation is based on ion-selective membranes separating the two electrolytes. Now Ulrich Schubert and colleagues have developed a redox-flow battery that uses organic polymers as the charge-storage material, in combination with inexpensive dialysis membranes and an aqueous sodium chloride solution as the electrolyte. The battery is non-toxic and cheaper to produce than traditional flow batteries. For renewable energy sources such as solar, wind, and hydroelectric to be effectively used in the grid of the future, flexible and scalable energy-storage solutions are necessary to mitigate output fluctuations 1 . Redox-flow batteries (RFBs) were first built in the 1940s 2 and are considered a promising large-scale energy-storage technology 1 , 3 , 4 . A limited number of redox-active materials 4 , 5 , 6 , 7 , 8 , 9 , 10 —mainly metal salts, corrosive halogens, and low-molar-mass organic compounds—have been investigated as active materials, and only a few membrane materials 3 , 5 , 11 , 12 , 13 , 14 , such as Nafion, have been considered for RFBs. However, for systems that are intended for both domestic and large-scale use, safety and cost must be taken into account as well as energy density and capacity, particularly regarding long-term access to metal resources, which places limits on the lithium-ion-based and vanadium-based RFB development 15 , 16 . Here we describe an affordable, safe, and scalable battery system, which uses organic polymers as the charge-storage material in combination with inexpensive dialysis membranes, which separate the anode and the cathode by the retention of the non-metallic, active (macro-molecular) species, and an aqueous sodium chloride solution as the electrolyte. This water- and polymer-based RFB has an energy density of 10 watt hours per litre, current densities of up to 100 milliamperes per square centimetre, and stable long-term cycling capability. The polymer-based RFB we present uses an environmentally benign sodium chloride solution and cheap, commercially available filter membranes instead of highly corrosive acid electrolytes and expensive membrane materials.

The enhancement of separation processes and electrochemical technologies such as water electrolysers 1 , 2 , fuel cells 3 , 4 , redox flow batteries 5 , 6 and ion-capture electrodialysis 7 depends on the development of low-resistance and high-selectivity ion-transport membranes. The transport of ions through these membranes depends on the overall energy barriers imposed by the collective interplay of pore architecture and pore–analyte interaction 8 , 9 . However, it remains challenging to design efficient, scaleable and low-cost selective ion-transport membranes that provide ion channels for low-energy-barrier transport. Here we pursue a strategy that allows the diffusion limit of ions in water to be approached for large-area, free-standing, synthetic membranes using covalently bonded polymer frameworks with rigidity-confined ion channels. The near-frictionless ion flow is synergistically fulfilled by robust micropore confinement and multi-interaction between ion and membrane, which afford, for instance, a Na + diffusion coefficient of 1.18 × 10 −9  m 2  s –1 , close to the value in pure water at infinite dilution, and an area-specific membrane resistance as low as 0.17 Ω cm 2 . We demonstrate highly efficient membranes in rapidly charging aqueous organic redox flow batteries that deliver both high energy efficiency and high-capacity utilization at extremely high current densities (up to 500 mA cm –2 ), and also that avoid crossover-induced capacity decay. This membrane design concept may be broadly applicable to membranes for a wide range of electrochemical devices and for precise molecular separation. The authors develop a strategy that allows the diffusion limit of ions in water to be approached for large-area, free-standing, synthetic membranes using covalently bonded polymer frameworks with rigidity-confined ion channels.

The presence of metal centres in synthetic polymers can impart interesting functionality on the resultant material. This Review Article focuses on the use of metal-containing polymers in a diverse range of applications, for example, in emissive and optical materials, in nanomaterials, as sensors, stimuli-responsive gels, catalysts and artifical metalloenzymes. Synthetic polymers containing metal centres are emerging as an interesting and broad class of easily processable materials with properties and functions that complement those of state-of-the-art organic macromolecular materials. A diverse range of different metal centres can be harnessed to tune macromolecular properties, from transition- and main-group metals to lanthanides. Moreover, the linkages that bind the metal centres can vary almost continuously from strong, essentially covalent bonds that lead to irreversible or 'static' binding of the metal to weak and labile, non-covalent coordination interactions that allow for reversible, 'dynamic' or 'metallosupramolecular', binding. Here we review recent advances and challenges in the field and illustrate developments towards applications as emissive and photovoltaic materials; as optical limiters; in nanoelectronics, information storage, nanopatterning and sensing; as macromolecular catalysts and artificial enzymes; and as stimuli-responsive materials. We focus on materials in which the metal centres provide function; although they can also play a structural role, systems where this is solely their purpose have not been discussed.

Decoupling the production of solar hydrogen from the diurnal cycle is a key challenge in solar energy conversion, the success of which could lead to sustainable energy schemes capable of delivering H 2 independent of the time of day. Here, we report a fully integrated photochemical molecular dyad composed of a ruthenium-complex photosensitizer covalently linked to a Dawson polyoxometalate that acts as an electron-storage site and hydrogen-evolving catalyst. Visible-light irradiation of the system in solution leads to charge separation and electron storage on the polyoxometalate, effectively resulting in a liquid fuel. In contrast to related, earlier dyads, this system enables the harvesting, storage and delayed release of solar energy. On-demand hydrogen release is possible by adding a proton donor to the dyad solution. The system is a minimal molecular model for artificial photosynthesis and enables the spatial and temporal separation of light absorption, fuel storage and hydrogen release. Decoupling the processes of light harvesting and catalytic hydrogen evolution could be a potentially important step in storing solar energy. This has now been achieved with a single molecular unit: a light-harvesting ruthenium complex–polyoxometalate dyad that absorbs light, separates and stores charge and then generates hydrogen on demand following the addition of a proton donor.

Improving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis. Reliability of stability data for perovskite solar cells is undermined by a lack of consistency in the test conditions and reporting. This Consensus Statement outlines practices for testing and reporting stability tailoring ISOS protocols for perovskite devices.

A bstract We evaluate the master integrals for the two-loop, planar box-diagrams contributing to the elastic scattering of muons and electrons at next-to-next-to leading-order in QED. We adopt the method of differential equations and the Magnus exponential series to determine a canonical set of integrals, finally expressed as a Taylor series around four space-time dimensions, with coefficients written as combination of generalised polylogarithms. The electron is treated as massless, while we retain full dependence on the muon mass. The considered integrals are also relevant for crossing-related processes, such as di-muon production at e + e − -colliders, as well as for the QCD corrections to top -pair production at hadron colliders.

A bstract We showcase the calculation of the master integrals needed for the two loop mixed QCD-QED virtual corrections to the neutral current Drell-Yan process ( q q ¯ → l + l − ). After establishing a basis of 51 master integrals, we cast the latter into canonical form by using the Magnus algorithm. The dependence on the lepton mass is then expanded such that potentially large logarithmic contributions are kept. After determining all boundary constants, we give the coefficients of the Taylor series around four space-time dimensions in terms of generalized polylogarithms up to weight four.

Within the last decade, inkjet printing technology has developed from only a text and graphic industry to a major topic of scientific research and development. Inkjet printing can be used as a highly reproducible noncontact patterning technique to print at high speeds either small or large areas with high quality features; it requires only small amounts of functional materials, which immediately lower production costs. Furthermore, inkjet printing reduces the amount of processing steps due to its additive technique of materials deposition, which further decreases productions costs. This contribution provides a literature survey covering the latest results in low temperature sintering inkjet-printed metal precursor materials in a fast and efficient manner, aiming for roll-to-roll processing. The prepared features can be used as interconnects and contacts for microelectronic applications, including organic light-emitting diodes, organic photovoltaics, and radio frequency identification tags.

A bstract We evaluate the master integrals for the two-loop non-planar box-diagrams contributing to the elastic scattering of muons and electrons at next-to-next-to-leading order in QED. We adopt the method of differential equations and the Magnus exponential to determine a canonical set of integrals, finally expressed as a Taylor series around four space-time dimensions, with coefficients written as combination of generalised polylogarithms. The electron is treated as massless, while we retain full dependence on the muon mass. The considered integrals are also relevant for crossing-related processes, such as di-muon production at e + e − colliders, as well as for the QCD corrections to top-pair production at hadron colliders. In particular our results, together with the planar master integrals recently computed, represent the complete set of functions needed for the evaluation of the photonic two-loop virtual next-to-next-to-leading order QED corrections to μe → μe and e + e − → μ + μ − .