Porous Semiconducting Polymer Nanoparticles as Intracellular Biophotonic Mediators to Modulate the Reactive Oxygen Species Balance.

The integration of nanotechnology with photoredox medicine has led to the emergence of biocompatible semiconducting polymer nanoparticles (SPNs) for the optical modulation of intracellular reactive oxygen species (ROS). However, the need for efficient photoactive materials capable of finely controlling the intracellular redox status with high spatial resolution at a nontoxic light density is still largely unmet. Herein, highly photoelectrochemically efficient photoactive polymer beads are developed. The photoactive material/electrolyte interfacial area is maximized by designing porous semiconducting polymer nanoparticles (PSPNs). PSPNs are synthesized by selective hydrolysis of the polyester segments of nanoparticles made of poly(3-hexylthiophene)-graft-poly(lactic acid) (P3HT-g-PLA). The photocurrent of PSPNs is 4.5-fold higher than that of nonporous P3HT-g-PLA-SPNs, and PSPNs efficiently reduce oxygen in an aqueous environment. PSPNs are internalized within endothelial cells and optically trigger ROS generation with a >1.3-fold concentration increase with regard to nonporous P3HT-SPNs, at a light density as low as a few milliwatts per square centimeter, fully compatible with in vivo, chronic applications.

3D printed PEDOT:PSS-based conducting and patternable eutectogel electrodes for machine learning on textiles.

The proliferation of medical wearables necessitates the development of novel electrodes for cutaneous electrophysiology. In this work, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is combined with a deep eutectic solvent (DES) and polyethylene glycol diacrylate (PEGDA) to develop printable and biocompatible electrodes for long-term cutaneous electrophysiology recordings. The impact of printing parameters on the conducting properties, morphological characteristics, mechanical stability and biocompatibility of the material were investigated. The optimised eutectogel formulations were fabricated in four different patterns -flat, pyramidal, striped and wavy- to explore the influence of electrode geometry on skin conformability and mechanical contact. These electrodes were employed for impedance and forearm EMG measurements. Furthermore, arrays of twenty electrodes were embedded into a textile and used to generate body surface potential maps (BSPMs) of the forearm, where different finger movements were recorded and analysed. Finally, BSPMs for three different letters (B, I, O) in sign-language were recorded and used to train a logistic regressor classifier able to reliably identify each letter. This novel cutaneous electrode fabrication approach offers new opportunities for long-term electrophysiological recordings, online sign-language translation and brain-machine interfaces.

Current Trends and Perspectives of Polymers in Batteries.

This Perspective aims to present the current status and future opportunities for polymer science in battery technologies. Polymers play a crucial role in improving the performance of the ubiquitous lithium ion battery. But they will be even more important for the development of sustainable and versatile post-lithium battery technologies, in particular solid-state batteries. In this article, we identify the trends in the design and development of polymers for battery applications including binders for electrodes, porous separators, solid electrolytes, or redox-active electrode materials. These trends will be illustrated using a selection of recent polymer developments including new ionic polymers, biobased polymers, self-healing polymers, mixed-ionic electronic conducting polymers, inorganic-polymer composites, or redox polymers to give some examples. Finally, the future needs, opportunities, and directions of the field will be highlighted.

Eutectogels as a Semisolid Electrolyte for Organic Electrochemical Transistors.

Organic electrochemical transistors (OECTs) are signal transducers offering high amplification, which makes them particularly advantageous for detecting weak biological signals. While OECTs typically operate with aqueous electrolytes, those employing solid-like gels as the dielectric layer can be excellent candidates for constructing wearable electrophysiology probes. Despite their potential, the impact of the gel electrolyte type and composition on the operation of the OECT and the associated device design considerations for optimal performance with a chosen electrolyte have remained ambiguous. In this work, we investigate the influence of three types of gel electrolytes-hydrogels, eutectogels, and iongels, each with varying compositions on the performance of OECTs. Our findings highlight the superiority of the eutectogel electrolyte, which comprises poly(glycerol 1,3-diglycerolate diacrylate) as the polymer matrix and choline chloride in combination with 1,3-propanediol deep eutectic solvent as the ionic component. This eutectogel electrolyte outperforms hydrogel and iongel counterparts of equivalent dimensions, yielding the most favorable transient and steady-state performance for both p-type depletion and p-type/n-type enhancement mode transistors gated with silver/silver chloride (Ag/AgCl). Furthermore, the eutectogel-integrated enhancement mode OECTs exhibit exceptional operational stability, reflected in the absence of signal-to-noise ratio (SNR) variation in the simulated electrocardiogram (ECG) recordings conducted continuously over a period of 5 h, as well as daily measurements spanning 30 days. Eutectogel-based OECTs also exhibit higher ECG signal amplitudes and SNR than their counterparts, utilizing the commercially available hydrogel, which is the most common electrolyte for cutaneous electrodes. These findings underscore the potential of eutectogels as a semisolid electrolyte for OECTs, particularly in applications demanding robust and prolonged physiological signal monitoring.

Biobased Acrylic Latexes/Sodium Carboxymethyl Cellulose Aqueous Binders for Lithium-Ion NMC 811 Cathodes.

The increasing demands for sustainable energy storage technologies have prompted extensive research in the development of eco-friendly materials for lithium-ion batteries (LIBs). This research article presents the design of biobased latexes, which are fluorine-free and rely on renewable resources, based on isobornyl methacrylate (IBOMA) and 2-octyl acrylate (2OA) to be used as binders in batteries. Three different compositions of latexes were investigated, varying the ratio of IBOMA and 2OA: (1) Poly2OA homopolymer, (2) Poly(2OA0,6-co-IBOMA0,4) random copolymer, and (3) PolyIBOMA homopolymer. The combination of the two monomers provided a balance between rigidity from the hard monomer (IBOMA) and flexibility from the soft one (2OA). The study evaluated the performance of the biobased latexes using sodium carboxymethyl cellulose (CMC) as a thickener and cobinder by fabricating LiNi0.8Mn0.1Co0.1O2 (NMC 811) cathodes. Also, to compare with the state of the art, organic processed PVDF electrodes were prepared. Among aqueous slurries, rheological analysis showed that the CMC + Poly(2OA0,6-co-IBOMA0,4) binder system resulted in the most stable and well-dispersed slurries. Also, the electrodes prepared with this latex demonstrated enhanced adhesion (210 ± 9 N m-1) and reduced cracks compared to other aqueous compositions. Electrochemical characterization revealed that the aqueous processed cathodes using the CMC + Poly(2OA0,6-co-IBOMA0,4) biobased latex displayed higher specific capacities than the control with no latex at high C-rates (100.3 ± 2.1 vs 64.5 ± 0.8 mAh g-1 at 5C) and increased capacity retention after 90 cycles at 0.5C (84% vs 81% for CMC with no latex). Overall, the findings of this study suggest that biobased latexes, specifically the CMC + Poly(2OA0,6-co-IBOMA0,4) composition, are promising as environmentally friendly binders for NMC 811 cathodes, contributing to the broader goal of achieving sustainable energy storage systems.

Recent Advances and Developments in Injectable Conductive Polymer Gels for Bioelectronics.

Soft matter bioelectronics represents an emerging and interdisciplinary research frontier aiming to harness the synergy between biology and electronics for advanced diagnostic and healthcare applications. In this context, a whole family of soft gels have been recently developed with self-healing ability and tunable biological mimetic features to act as a tissue-like space bridging the interface between the electronic device and dynamic biological fluids and body tissues. This review article provides a comprehensive overview of electroactive polymer gels, formed by noncovalent intermolecular interactions and dynamic covalent bonds, as injectable electroactive gels, covering their synthesis, characterization, and applications. First, hydrogels crafted from conducting polymers (poly(3,4-ethylene-dioxythiophene) (PEDOT), polyaniline (PANi), and polypyrrole (PPy))-based networks which are connected through physical interactions (e.g., hydrogen bonding, π-π stacking, hydrophobic interactions) or dynamic covalent bonds (e.g., imine bonds, Schiff-base, borate ester bonds) are addressed. Injectable hydrogels involving hybrid networks of polymers with conductive nanomaterials (i.e., graphene oxide, carbon nanotubes, metallic nanoparticles, etc.) are also discussed. Besides, it also delves into recent advancements in injectable ionic liquid-integrated gels (iongels) and deep eutectic solvent-integrated gels (eutectogels), which present promising avenues for future research. Finally, the current applications and future prospects of injectable electroactive polymer gels in cutting-edge bioelectronic applications ranging from tissue engineering to biosensing are outlined.

ROS-Responsive 4D Printable Acrylic Thioether-Based Hydrogels for Smart Drug Release.

Reactive oxygen species (ROS) play a key role in several biological functions like regulating cell survival and signaling; however, their effect can range from beneficial to nondesirable oxidative stress when they are overproduced causing inflammation or cancer diseases. Thus, the design of tailor-made ROS-responsive polymers offers the possibility of engineering hydrogels for target therapies. In this work, we developed thioether-based ROS-responsive difunctional monomers from ethylene glycol/thioether acrylate (EGnSA) with different lengths of the EGn chain (n = 1, 2, 3) by the thiol-Michael addition click reaction. The presence of acrylate groups allowed their photopolymerization by UV light, while the thioether groups conferred ROS-responsive properties. As a result, smart PEGnSA hydrogels were obtained, which could be processed by four-dimensional (4D) printing. The mechanical properties of the hydrogels were determined by rheology, pointing out a decrease of the elastic modulus (G') with the length of the EG segment. To enhance the stability of the hydrogels after swelling, the EGnSA monomers were copolymerized with a polar monomer, 2-hydroxyethyl acrylate (HEA), leading to P[(EGnSA)x-co-HEAy] with improved compatibility in aqueous media, making it a less brittle material. Swelling properties of the hydrogels increased in the presence of hydrogen peroxide, a kind of ROS, reaching values of ≈130% for P[(EG3SA)7-co-HEA93] which confirms the stimuli-responsive properties. Then, the P[(EG3SA)x-co-HEAy] hydrogels were employed as matrixes for the encapsulation of a chemotherapeutic drug, 5-fluorouracil (5FU), which showed sustained release over time modulated by the presence of H2O2. Finally, the effect of the 5-FU release from P[(EG3SA)x-co-HEAy] hydrogels was tested in vitro with melanoma cancer cells B16F10, pointing out B16F10 growth inhibition values in the range of 40-60% modulated by the EG3SA percentage and the presence or absence of ROS agents, thus confirming their excellent ROS-responsive properties for the treatment of localized pathologies.

All-Polymer Nanocomposite as Salt-Free Solid Electrolyte for Lithium Metal Batteries.

Solid polymer electrolytes that combine both a high lithium-ion transference number and mechanical properties at high temperatures are searched for improving the performance of batteries. Here, we show a salt-free all-polymer nanocomposite solid electrolyte for lithium metal batteries that improves the mechanical properties and shows a high lithium-ion transference number. For this purpose, lithium sulfonamide-functionalized poly(methyl methacrylate) nanoparticles (LiNPs) of very small size (20-30 nm) were mixed with poly(ethylene oxide) (PEO). The morphology of all-polymer nanocomposites was first investigated by transmission electron microscopy (TEM), showing a good distribution of nanoparticles (NPs) even at high contents (50 LiNP wt %). The crystallinity of PEO was investigated in detail and decreased with the increasing concentration of LiNPs. The highest ionic conductivity value for the PEO 50 wt % LiNP nanocomposite at 80 °C is 1.1 × 10-5 S cm-1, showing a lithium-ion transference number of 0.68. Using dynamic mechanic thermal analysis (DMTA), it was shown that LiNPs strengthen PEO, and a modulus of ≈108 Pa was obtained at 80 °C for the polymer nanocomposite. The nanocomposite solid electrolyte was stable with respect to lithium in a Li||Li symmetrical cell for 1000 h. In addition, in a full solid-state battery using LiFePO4 as the cathode and lithium metal as the anode, a specific capacity of 150 mAhg-1 with a current density of 0.05 mA cm-2 was achieved.

Light-Based 3D Multi-Material Printing of Micro-Structured Bio-Shaped, Conducting and Dry Adhesive Electrodes for Bioelectronics.

In this work, a new method of multi-material printing in one-go using a commercially available 3D printer is presented. The approach is simple and versatile, allowing the manufacturing of multi-material layered or multi-material printing in the same layer. To the best of the knowledge, it is the first time that 3D printed Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) micro-patterns combining different materials are reported, overcoming mechanical stability issues. Moreover, the conducting ink is engineered to obtain stable in-time materials while retaining sub-100 µm resolution. Micro-structured bio-shaped protuberances are designed and 3D printed as electrodes for electrophysiology. Moreover, these microstructures are combined with polymerizable deep eutectic solvents (polyDES) as functional additives, gaining adhesion and ionic conductivity. As a result of the novel electrodes, low skin impedance values showed suitable performance for electromyography recording on the forearm. Finally, this concluded that the use of polyDES conferred stability over time, allowing the usability of the electrode 90 days after fabrication without losing its performance. All in all, this demonstrated a very easy-to-make procedure that allows printing PEDOT:PSS on soft, hard, and/or flexible functional substrates, opening up a new paradigm in the manufacturing of conducting multi-functional materials for the field of bioelectronics and wearables.

Fast Visible-Light 3D Printing of Conductive PEDOT:PSS Hydrogels.

Functional inks for light-based 3D printing are actively being searched for being able to exploit all the potentialities of additive manufacturing. Herein, a fast visible-light photopolymerization process is showed of conductive PEDOT:PSS hydrogels. For this purpose, a new Type II photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine (TEA), and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is investigated for the visible light photopolymerization of acrylic monomers. PEDOT:PSS has a dual role by accelerating the photoinitiation process and providing conductivity to the obtained hydrogels. Using this PIS, full monomer conversion is achieved in less than 2 min using visible light. First, the PIS mechanism is studied, proposing that electron transfer between the triplet excited state of the dye (3 Rf*) and the amine (TEA) is catalyzed by PEDOT:PSS. Second, a series of poly(2-hydroxyethyl acrylate)/PEDOT:PSS hydrogels with different compositions are obtained by photopolymerization. The presence of PEDOT:PSS negatively influences the swelling properties of hydrogels, but significantly increases its mechanical modulus and electrical properties. The new PIS is also tested for 3D printing in a commercially available Digital Light Processing (DLP) 3D printer (405 nm wavelength), obtaining high resolution and 500 µm hole size conductive scaffolds.

Bio-based ether solvent and ionic liquid electrolyte for sustainable sodium-air batteries.

Sodium-air batteries (SABs) are receiving considerable attention for the development of next generation battery alternatives due to their high theoretical energy density (up to 1105 W h kg-1). However, most of the studies on this technology are still based on organic solvents; in particular, diglyme, which is highly flammable and toxic for the unborn child. To overcome these safety issues, this research investigates the first use of a branched ether solvent 1,2,3-trimethoxypropane (TMP) as an alternative electrolyte to diglyme for SABs. Through this work, the reactivity of the central tertiary carbon in TMP towards bare sodium metal was identified, while the addition of N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyr][TFSI]) as a co-solvent proved to be an effective strategy to limit the reactivity. Moreover, a Na-ß-alumina disk was employed for anode protection, to separate the TMP-based electrolyte from the sodium metal. The new cell design resulted in improved cell performance: discharge capacities of up to 1.92 and 2.31 mA h cm-2 were achieved for the 16.6 mol% NaTFSI in TMP and 16.6 mol% NaTFSI in TMP/[C4mpyr][TFSI] compositions, respectively. By means of SEM, Raman and 23Na NMR techniques, NaO2 cubes were identified to be the major discharge product for both electrolyte compositions. Moreover, the hybrid electrolyte was shown to hinder the formation of side-products during discharge - the ratio of NaO2 to side-products in the hybrid electrolyte was 2.4 compared with 0.8 for the TMP-based electrolyte - and a different charge mechanism for the dissolution of NaO2 cubes for each electrolyte was observed. The findings of this work demonstrate the high potential of TMP as a base solvent for SABs, and the importance of careful electrolyte composition design in order to step towards greener and less toxic batteries.

Hydrophobic Eutectogels as Electrodes for Underwater Electromyography Recording.

Underwater recording remains a critical challenge in bioelectronics because traditional flexible electrodes can not fulfill essential requirements such as stability and steady conductivity in aquatic environments. Herein, we show the use of elastic gels made of hydrophobic natural eutectic solvents as water-resistant electrodes. These eutectogels are designed with tailorable mechanical properties via one-step photopolymerization of acrylic monomers in different eutectic mixtures composed of fatty acids and menthol. The low viscosity of the eutectics turns the formulations into suitable inks for 3D printing, allowing fast manufacturing of complex objects. Furthermore, the hydrophobic nature of the building blocks endows the eutectogels with excellent stability and low water uptake. The obtained flexible eutectogel electrodes can record real-time electromyography (EMG) signals with low interference in the air and underwater.

Bio-Based Polyhydroxyanthraquinones as High-Voltage Organic Electrode Materials for Batteries.

Organic materials have gained much attention as sustainable electrode materials for batteries. Especially bio-based organic electrode materials (OEMs) are very interesting due to their geographical independency and low environmental impact. However, bio-based OEMs for high-voltage batteries remain scarce. Therefore, in this work, a family of bio-based polyhydroxyanthraquinones (PHAQs)-namely 1,2,3,4,5,6,7,8-octahydroxyanthraquinone (OHAQ), 1,2,3,5,6,7-hexahydroxyanthraquinone (HHAQ), and 2,3,6,7-tetrahydroxyanthraquinone (THAQ)-and their redox polymers were synthesized. These PHAQs were synthesized from plant-based precursors and exhibit both a high-potential polyphenolic redox couple (3.5-4.0 V vs Li/Li+) and an anthraquinone redox moiety (2.2-2.8 V vs Li/Li+), while also showing initial charging capacities of up to 381 mAh g-1. To counteract the rapid fading caused by dissolution into the electrolyte, a facile polymerization method was established to synthesize PHAQ polymers. For this, the polymerization of HHAQ served as a model reaction where formaldehyde, glyoxal, and glutaraldehyde were tested as linkers. The resulting polymers were investigated as cathode materials in lithium metal batteries. PHAQ polymer composites synthesized using formaldehyde as linker and 10 wt % multiwalled carbon nanotubes (MWCNTs), namely poly(THAQ-formaldehyde)-10 wt % MWCNTs and poly(HHAQ-formaldehyde)-10 wt % MWCNTs, exhibited the best cycling performance in the lithium metal cells, displaying a high-voltage discharge starting at 4.0 V (vs Li/Li+) and retaining 81.6 and 77.3 mAh g-1, respectively, after 100 cycles.

Bimodal modulation of in vitro angiogenesis with photoactive polymer nanoparticles.

Angiogenesis is a fundamental process in biology, given the pivotal role played by blood vessels in providing oxygen and nutrients to tissues, thus ensuring cell survival. Moreover, it is critical in many life-threatening pathologies, like cancer and cardiovascular diseases. In this context, conventional treatments of pathological angiogenesis suffer from several limitations, including low bioavailability, limited spatial and temporal resolution, lack of specificity and possible side effects. Recently, innovative strategies have been explored to overcome these drawbacks based on the use of exogenous nano-sized materials and the treatment of the endothelial tissue with optical or electrical stimuli. Here, conjugated polymer-based nanoparticles are proposed as exogenous photo-actuators, thus combining the advantages offered by nanotechnology with those typical of optical stimulation. Light excitation can achieve high spatial and temporal resolution, while permitting minimal invasiveness. Interestingly, the possibility to either enhance (≈+30%) or reduce (up to -65%) the angiogenic capability of model endothelial cells is demonstrated, by employing different polymer beads, depending on the material type and the presence/absence of the light stimulus. In vitro results reported here represent a valuable proof of principle of the reliability and efficacy of the proposed approach and should be considered as a promising step towards a paradigm shift in therapeutic angiogenesis.

Carrageenans as Sustainable Water-Processable Binders for High-Voltage NMC811 Cathodes.

Poly(vinylidene fluoride) (PVDF) is the most common binder for cathode electrodes in lithium-ion batteries. However, PVDF is a fluorinated compound and requires toxic N-methyl-2-pyrrolidone (NMP) as a solvent during the slurry preparation, making the electrode fabrication process environmentally unfriendly. In this study, we propose the use of carrageenan biopolymers as a sustainable source of water-processable binders for high-voltage NMC811 cathodes. Three types of carrageenan (Carr) biopolymers were investigated, with one, two, or three sulfonate groups (SO3-), namely, kappa, iota, and lambda carrageenans, respectively. In addition to the nature of carrageenans, this article also reports the optimization of the cathode formulations, which were prepared by using between 5 wt % of the binder to a lower amount of 2 wt %. Processing of the aqueous slurries and the nature of the binder, in terms of the morphology and electrochemical performance of the electrodes, were also investigated. The Carr binder with 3SO3- groups (3SO3-Carr) exhibited the highest discharge capacities, delivering 133.1 mAh g-1 at 3C and 105.0 mAh g-1 at 5C, which was similar to the organic-based PVDF electrode (136.1 and 108.7 mAh g-1, respectively). Furthermore, 3SO3-Carr reached an outstanding capacity retention of 91% after 90 cycles at 0.5C, which was attributed to a homogeneous NMC811 and a conductive carbon particle dispersion, superior adhesion strength to the current collector (17.3 ± 0.7 N m-1 vs 0.3 ± 0.1 N m-1 for PVDF), and reduced charge-transfer resistance. Postmortem analysis unveiled good preservation of the NMC811 particles, while the 1SO3-Carr and 2SO3-Carr electrodes showed damaged morphologies.

Semiconducting Polymer Nanoporous Thin Films as a Tool to Regulate Intracellular ROS Balance in Endothelial Cells.

The design of soft and nanometer-scale photoelectrodes able to stimulate and promote the intracellular concentration of reactive oxygen species (ROS) is searched for redox medicine applications. In this work, we show semiconducting polymer porous thin films with an enhanced photoelectrochemical generation of ROS in human umbilical vein endothelial cells (HUVECs). To achieve that aim, we synthesized graft copolymers, made of poly(3-hexylthiophene) (P3HT) and degradable poly(lactic acid) (PLA) segments, P3HT-g-PLA. In a second step, the hydrolysis of sacrificial PLA leads to nanometer-scale porous P3HT thin films. The pore sizes in the nm regime (220-1200 nm) were controlled by the copolymer composition and the structural arrangement of the copolymers during the film formation, as determined by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The porous P3HT thin films showed enhanced photofaradaic behavior, generating a higher concentration of ROS in comparison to non-porous P3HT films, as determined by scanning electrochemical microscopy (SECM) measurements. The exogenous ROS production was able to modulate the intracellular ROS concentration in HUVECs at non-toxic levels, thus affecting the physiological functions of cells. Results presented in this work provide an important step forward in the development of new tools for precise, on-demand, and non-invasive modulation of intracellular ROS species and may be potentially extended to many other physiological or pathological cell models.

Lignin-Derivative Ionic Liquids as Corrosion Inhibitors.

Corrosion is a significant problem that negatively affects a wide range of structures and buildings, resulting in their premature failure, which causes safety hazards and significant economic loss. For this reason, various approaches have been developed to prevent or minimize the effects of corrosion, including corrosion inhibitors. Recently, biobased inhibitors have gained a certain interest thanks to their unique properties, eco-friendliness, and availability. Among all the green precursors, lignin is of particular interest, being a natural polymer that can be obtained from different sources including agricultural residues. Corrosion inhibitors based on ionic liquids (ILs) also present interesting advantages, such as low volatility and high tunability. If combined, it may be possible to obtain new lignin-based ILs that present interesting corrosion inhibitor properties. In this work, the inhibition properties of new biobased lignin ILs and the influence of anions and cations on the corrosion of mild steel in an aqueous solution of 0.01 M NaCl were investigated by Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) and Cyclic Potentiodynamic Polarization (CPP). Moreover, the surface was characterized using SEM, EDS, and optical profilometry. The IL choline syringate showed promising performance, reducing the corrosion current after 24 h immersion in 0.01 M sodium chloride, from 1.66 µA/cm2 for the control to 0.066 µA/cm2 with 10 mM of the IL present. In addition to its performance as a corrosion inhibitor, both components of this IL also meet or exceed the current additional desired properties of such compounds, being readily available, and well tolerated in organisms and the environment.

Polyimides as Promising Cathodes for Metal-Organic Batteries: A Comparison between Divalent (Ca2+, Mg2+) and Monovalent (Li+, Na+) Cations.

Ca- and Mg-based batteries represent a more sustainable alternative to Li-ion batteries. However, multivalent cation technologies suffer from poor cation mass transport. In addition, the development of positive electrodes enabling reversible charge storage currently represents one of the major challenges. Organic positive electrodes, in addition to being the most sustainable and potentially low-cost candidates, compared with their inorganic counterparts, currently present the best electrochemical performances in Ca and Mg cells. Unfortunately, organic positive electrodes suffer from relatively low capacity retention upon cycling, the origin of which is not yet fully understood. Here, 1,4,5,8-naphthalenetetracarboxylic dianhydride-derived polyimide was tested in Li, Na, Mg, and Ca cells for the sake of comparison in terms of redox potential, gravimetric capacities, capacity retention, and rate capability. The redox mechanisms were also investigated by means of operando IR experiments, and a parameter affecting most figures of merit has been identified: the presence of contact ion-pairs in the electrolyte.

Interface engineering for high-performance, triple-halide perovskite-silicon tandem solar cells.

Improved stability and efficiency of two-terminal monolithic perovskite-silicon tandem solar cells will require reductions in recombination losses. By combining a triple-halide perovskite (1.68 electron volt bandgap) with a piperazinium iodide interfacial modification, we improved the band alignment, reduced nonradiative recombination losses, and enhanced charge extraction at the electron-selective contact. Solar cells showed open-circuit voltages of up to 1.28 volts in p-i-n single junctions and 2.00 volts in perovskite-silicon tandem solar cells. The tandem cells achieve certified power conversion efficiencies of up to 32.5%.

Mixed Conductive, Injectable, and Fluorescent Supramolecular Eutectogel Composites.

Eutectogels are an emerging family of soft ionic materials alternative to ionic liquid gels and organogels, offering fresh perspectives for designing functional dynamic platforms in water-free environments. Herein, the first example of mixed ionic and electronic conducting supramolecular eutectogel composites is reported. A fluorescent glutamic acid-derived low-molecular-weight gelator (LMWG) was found to self-assemble into nanofibrillar networks in deep eutectic solvents (DES)/poly(3,4-ethylenedioxythiophene) (PEDOT): chondroitin sulfate dispersions. These dynamic materials displayed excellent injectability and self-healing properties, high ionic conductivity (up to 10-2  S cm-1 ), good biocompatibility, and fluorescence imaging ability. This set of features turns the mixed conducting supramolecular eutectogels into promising adaptive materials for bioimaging and electrostimulation applications.