Electrolytes critically influence the electrochemical performance and cycle life of lithium ion batteries (LIBs). This holds especially for organic redox polymer-based batteries, such as those employing poly(3-vinyl-N-methylphenoxazine) (PVMPO), where solubility limits performance in conventional ethylene carbonate (EC)/ dimethyl carbonate (DMC)-based electrolytes. Reducing EC content has shown solubility suppression when using ethyl methyl carbonate (EMC) as a co-solvent, however, capacity fading persists due to PVMPO electrode degradation. To address this degradation, this study explores the use of EC-free electrolytes, with and without fluoroethylene carbonate (FEC). Electrochemical investigations, UltraViolet/Visible (UV/Vis) spectroscopy, post-cycling Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) mapping, and X-ray Photoelectron Spectroscopy (XPS) analyses are employed to evaluate solubility, interfacial properties, and electrode integrity. The EC-free electrolyte system with FEC retains 95 mAh g‒1, while that without FEC retains 86 mAh g‒1, outperforming the 76 mAh g‒1 observed in EC-based systems after 500 cycles at 1C. FEC containing electrolyte systems display reduced interfacial resistance, fewer surface cracks, and minimal electrode degradation. These findings demonstrate that EC-free electrolytes, particularly with FEC, effectively suppress electrode degradation and enhance the cycle life of organic LIBs.

Organic redox-active electrode materials are gaining increasing attention due to their eco-friendliness, abundance, and structural versatility. However, their processing typically depends on poly(vinylidene difluoride) (PVdF) as binder and N-methyl-2-pyrrolidone (NMP) as solvent, both are expensive and hazardous. While aqueous processing methods are well established for inorganic electrodes, their application to organic materials remains largely unexplored. This study investigates the use of water-processable binders, specifically sodium carboxymethyl cellulose (Na-CMC) and styrene-butadiene rubber (SBR) for fabricating poly(3-vinyl-N-methylphenothiazine) electrodes. Key factors influencing electrode performance and microstructure were systematically studied, including the choice of conductive additive, mixing procedures, hot-pressing, and densification. Among these, the selection of conductive additive, mixing method, and room temperature densification at different pressure had the most pronounced impact on electrochemical performance. Electrodes using Na-CMC as the primary binder retained ≈90% of their theoretical capacity over 1000 cycles at 1C rate, comparable to PVdF-based electrodes. While increased densification pressure improved electrode uniformity, it had a detrimental effect on electrochemical performance. Introducing SBR as a co-binder at various weight ratios enhanced mechanical integrity and mitigated the negative effects of high densification pressure, ultimately leading to improved electrochemical performance under these applied operation conditions.

Rechargeable aluminum batteries (RABs) are promising post-lithium energy storage systems due to the high abundance and volumetric capacity of aluminum, yet stable positive electrodes development remains a bottleneck. Cross-linked poly(3-vinyl-N-methylphenothiazine) (X-PVMPT) as a p-type redox polymer shows reversible two-electron redox chemistry at relatively high potentials and excellent cycling stability in RABs when paired with chloroaluminate-based ionic liquid electrolytes. Here, we present the investigation of volume expansion and morphological evolution of X-PVMPT composite electrodes during cycling using electrochemical (ec-) atomic force microscopy (AFM) and cyclic voltammetry. ec-AFM data reveals the dynamics of reversible expansion during anion insertion and (ir)reversible changes associated with prolonged cycling. In situ linescan profiling and 2D nanomechanical imaging allows visualization of pronounced and reversible volume change during cycling, associated with the insertion of AlCl4-/ Al2Cl7- anions. Complementary electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) measurements validate these observations at the macroscopic scale, confirming that volume expansion and electrochemical stiffening are homogeneous, bulk phenomena of the X-PVMPT framework. We determined a reversible swelling amplitude of 1.1 +/- 0.1 & micro;m during anion insertion for a 9.6 & micro;m thick film, correlated with a 4-fold increase in stiffness. While initial cycles involve large-scale structural changes, the network rapidly reaches a mechanically stabilized state after the initial cycle, where the polymer matrix undergoes irreversible reorganization. After the steady-state phase (from cycle 120 onwards), the swelling amplitude drops by 60-75% to 0.3 - 0.4 & micro;m with sustained faradaic performance, highlighting the ability of the cross-linked matrix to establish ion-conduction pathways during prolonged cycling.

Chiral conjugated nanohoops are attractive based on their potential circularly polarized luminescence (CPL) activity. Using an approach of merging chiral pillar[5]arene (P[5]A) macrocycles with a conjugated nanohoop architecture, we report the enantioselective synthesis of [n]cycloparaphenylene ([n]CPP)-P[5]A conjugates, [n]CPP-PAn/3 (n = 9, 12 and 15), using a Pt-mediated macrocyclization of enantiopure phenylene-extended P[5]A. The three multi-macrocycles exhibit photophysical behavior closely related to their parent [n]CPPs. Their high fluorescence quantum yield (Φ F = 56-81%) and circularly polarized luminescence (CPL) with dissymmetry factors g lum of 4.2 × 10-4-3.0 × 10-3 lead to CPL brightnesses B CPL of up to 96 M-1 cm-1 in [15]CPP-PA3. This study presents the selective synthesis of statistically disfavored isomers to obtain high-symmetry chiral nanohoops suitable for chiroptical applications.

Flexible electronic systems require energy-dense batteries that can tolerate repeated mechanical deformation without loss of electrochemical performance. Conventional flexible battery architectures typically rely on weakly bound electrode-electrolyte interfaces, which are prone to interfacial resistance, disrupted mass transport, and mechanical failure under flexion. A covalent interface engineering strategy based on electrochemical sol-gel deposition is presented to create mechanically robust, chemically bonded electrochemical interfaces. In this approach, an similar to 80 nm thick conformal silanol gel layer is electrochemically deposited to chemically anchor ionic liquid electrolytes to graphite cathodes in flexible aluminum-graphite batteries. This method enables precise control over interfacial thickness and chemistry while preserving electrode flexibility. Electrochemical characterizations using variable-rate cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic cycling demonstrate that covalent interface formation suppresses flex-induced interfacial resistance, shifts charge storage toward surface-controlled regimes, and enables rapid ion transport through ordered interfacial pathways without compromising electronic conductivity. Flexible full cells exhibit stable long-term cycling for >260 cycles with a specific capacity of 56 mAh/g of graphite. Individual electrodes retain electrochemical performance under bending up to 180 degrees. By decoupling mechanical compliance from electrochemical stability, this work establishes a generalizable synthesis strategy for inherently flexible batteries and introduces an interface design paradigm for next-generation wearable and integrated energy storage devices.

Conjugated nanohoops, such as [n]cycloparaphenylenes ([n]CPPs) and derivatives, exhibit unique structural and optoelectronic properties, making them promising candidates for applications in optoelectronic materials, and as hosts for supramolecular chemistry. Using π-systems unsymmetric to rotation or incorporating chiral units can furnish chiral nanohoops. We herein present the synthesis and characterization of diketo[8]- and diketo[9]CPPs, along with their corresponding dibenzo[a,e]pentalene (DBP) derivatives, DBP[8]- and DBP[9]CPP. Due to the central chirality of the diketone-units, these nanohoops are chiral without the possibility of racemization through rotation and show distinct chiroptical properties. The diketo[n]CPPs possess high fluorescence quantum yields of 87% (n = 8) and 92% (n = 9). The shape-adaptive properties of diketo[n]CPPs, facilitated by the tunable kink angle of the diketo unit, enable efficient host-guest interactions with fullerenes. Fluorescence titration revealed a similar binding constant for both fullerenes C60 and C70 (5 × 104 to 7 × 104 M-1 in toluene), corroborated by DFT calculations that illustrate adaptive changes in nanohoop geometry upon fullerene complexation. ESI-MS is employed to generate ionized [1 : 1] host-guest complexes of diketo[9]CPP and DBP[9]CPP with C60 and C70 as guests. The relative stabilities of these complexes are evaluated in energy-resolved collision experiments.

Anion-rocking chair batteries, functioning without any metals, are intriguing candidates as alternative, more sustainable energy storage systems. They can be operated by using two types of p-type organic electrode-active materials (OAMs) with low and high redox potentials for the negative and positive electrode, respectively. However, identifying compatible material pairs delivering a potential difference above 1.5 V is challenging. Viologens are promising candidates as low-potential OAMs, but they usually lack stability when cycled over both redox processes. Herein, we report on linear and crosslinked N-aryl viologen polymers with enhanced electrochemical stability over both redox processes in lithium half-cells. We employ these as negative electrodes in anion-rocking chair full-cells with a dimethoxyphenothiazine-polymer-based positive electrode, able to undergo two reversible oxidations. The full-cell, using 2 m LiClO4 in PC as electrolyte, delivered a voltage of ca. 1.8 V and a capacity of up to 78 mAh g(-1) and could be cycled over 100 cycles with a capacity retention of 71%. We further demonstrate a metal-free all-organic full-cell using nBu(4)NClO(4) as electrolyte salt that delivers an even higher specific discharge capacity of up to 88 mAh g(-1). This work constitutes a step forward toward anion-rocking chair batteries with attractive cell voltages exceeding 1.5 V.

Organic electrode-active materials offer a sustainable pathway toward sodium-based batteries, yet their application is hindered by electrolyte dissolution, limited conductivity, and synthetic challenges. Herein, we present an efficient nickel-free synthesis of poly(pyrene-4,5,9,10-tetraone) (PPTO), a high-capacity organic carbonyl-based polymer, via oxidative Pd-catalyzed homopolymerization of propylene glycol-protected PTO boronic esters. Among different conductive carbon-based electrodes, a PPTO@CNTs@Ketjen Black composite electrode achieves a reversible capacity of 286 mAh g-1 at 1 A g-1, 72% capacity retention over 500 cycles, and delivers 201 mAh g-1 even at 10 A g-1. An energy density of 549 Wh kg-1 (at low rates) and 346 Wh kg-1 (at high rates) is achieved based on active-material mass under half-cell conditions (275 Wh kg-1 based on total electrode mass). Ex situ spectroscopy, combined with theoretical calculations, reveals a two-electron redox process of each PTO unit with possible intermolecular interactions stabilizing the reduced state. Kinetic studies demonstrate rapid Na+ transport (D Na + approximate to 10-10 cm2 s-1) and capacitive-dominated storage. Tomographic 3D image data reconstruction highlights the favorable microstructure of the CNT/Ketjen Black composite in hindering PPTO dissolution. This work provides insights into the interplay between polymer chemistry, electrode architecture, and ion transport, offering design principles for organic electrode materials for sodium-based batteries.

Organic electrode-active materials (OAMs) represent an alternative to (transition-) metalbased materials used in conventional battery cells. Reversibly oxidizable p-type OAMs allow realizing full-organic battery cells operating in an anion-rocking chair mechanism. In the search for p-type materials with a low redox potential so-called super-electron-donors (SEDs) are a promising class of molecules. Herein, we implement a bi(benzimidazole) (BBI)-based SED into three polymers, PBBI, a conjugated homopolymer, PSBBI as a styrene-based side chain polymer, and X-PSBBI as its crosslinked counterpart. Their properties as potential OAMs in lithium-organic half cells were investigated, and PBBI was found to be electrochemically inactive. The sidechain polymers showed reversible cycling behavior in binder-free powder electrodes in LiBF4-based electrolytes, even though the accessible capacity quickly faded. As possible degradation mechanism we propose decomposition via a dicarbene species as a plausible, reactive key species. This study showcases bi(benzimidazole)s as redox-active groups in OAMs with low redox potential and provides insight into challenges associated with obtaining a reversibly cycling behavior in battery electrodes.

Antiaromatic compounds are often difficult to work with due to their relative instability in comparison with aromatic analogues. As a consequence, their application in functional materials remains in its infancy. Here, we report the synthesis of porous M II 4 L 6 (M = Fe, Zn) coordination cages equipped with dibenzo[ a , e ]pentalene panels involving the antiaromatic motif of pentalene stabilized by benzannulation. Both cages encapsulate fullerenes, undergoing pronounced structural reconfiguration upon C 60 inclusion, and displaying broader affinity for polycyclic aromatic hydrocarbons. The cages selectively bind anthraquinone over its reduced form and interact with steroids such as testosterone and cholesterol. Remarkably, the chemical shifts of the guests are affected by the Clar sextets rather than the pentalene motif. These assemblies represent only the second reported example of a supramolecular cage with a cavity fully enclosed by antiaromatic walls, offering new insights into the effects of (anti)aromaticity in confined spaces and demonstrating that appropriately modified antiaromatic units do not inevitably induce paramagnetic deshielding of encapsulated guests.

Poly(1,4-anthraquinone) (P14AQ) has emerged as a promising cathode material, offering high capacity and good cycling stability, yet the atomic-scale mechanisms governing metal-ion binding and electrochemical behavior remain poorly understood. To address this, we investigate the binding mechanisms of Li, Na, Mg, and Ca to P14AQ using quantum mechanical methods, particularly DFT and DFTB. A key challenge lies in the material's structural complexity: multiple conformers of P14AQ are energetically similar but kinetically isolated due to significant energy barriers. To account for this, we develop an automated method to generate all unique P14AQ conformers for a periodic polymer chain without rotational duplicates through an orientation labeling scheme. For each conformer, we systematically place a metal atom adjacent to every oxygen site, enabling a complete exploration of binding configurations. We observe two structural motifs: a single metal-oxygen bond and coordination to two opposite oxygen atoms. While Li and Na exhibit continuous energy distributions, Mg and Ca show an energy gap between the two motifs, with a strong preference for the two-oxygen binding configuration. Galvanostatic measurements support these findings by showing lower gravimetric capacities for Ca and Mg than for Li and Na. For Na, the different numbers of metal-oxygen bonds are reflected in the two voltage plateaus observed experimentally. Overall, the combined computational and experimental results explain the higher capacity of monovalent ions in P14AQ: divalent ions cannot bind efficiently to a single oxygen site due to unfavorable energetics, and the conformational distribution of the polymer chain prevents optimal coordination.

Antiaromatic compounds are often difficult to work with due to their relative instability in comparison with aromatic analogues. As a consequence, their application in functional materials remains in its infancy. Here, we report the synthesis of porous M II 4L6 (M = Fe, Zn) coordination cages equipped with dibenzo-[a,e]-pentalene panels involving the antiaromatic motif of pentalene stabilized by benzannulation. Both cages encapsulate fullerene C60, with the more adaptable zinc-(II) cage also binding C70, undergoing pronounced structural reconfiguration upon C60 inclusion, and displaying broader affinity for polycyclic aromatic hydrocarbons. The cages selectively bind anthraquinone over its reduced form and interact with steroids such as testosterone and cholesterol. Remarkably, the chemical shifts of the guests are affected by the aromatic Clar sextets rather than the antiaromatic pentalene motif. These assemblies represent only the second reported example of a supramolecular cage with a cavity fully enclosed by antiaromatic walls and demonstrate that benzannulated antiaromatic motifs can be incorporated into cages without interrupting conventional host-guest behavior, while simultaneously allowing for a systematic tuning of magnetic shielding effects.

Thermally activated delayed fluorescence (TADF) compounds have found great application as photocatalysts in recent years. Their use as photosensitizers (PS), however, is still limited although they have huge potential as abundant alternatives to traditional noble metal-based PSs, such as [Ru(bpy)3]2+. We herein investigate the TADF compound 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) as a PS together with the catalyst cobaloxime (Co(dmgH)2(py)Cl) in the photochemical hydrogen evolution reaction (HER). Systematic optimization of the solvent composition, 4CzIPN and catalyst concentration, and sacrificial electron donor (SED) identified ammonium ascorbate as the most effective SED under the conditions tested. Under optimized conditions, the system reached a TON of 6451 ± 82 after 20 h irradiation. Stern-Volmer quenching experiments and scalar-relativistic quantum-chemical calculations provided rate constants for the different processes in the photosensitization mechanism, demonstrating that the quenching of the excited singlet state (S1) of 4CzIPN by ammonium ascorbate is by far more dominant than the quenching of its excited triplet state (T1). This work demonstrates that 4CzIPN can sensitize the cobaloxime-catalyzed light-driven HER with ammonium ascorbate as the SED and provides mechanistic insight into the role of singlet- and triplet-state quenching in TADF photosensitization.

The design flexibility of organic materials has enabled numerous applications for energy storage systems. However, few examples of low-potential p-type materials for the negative electrode are known in the field of organic batteries, particularly relevant for anion-rocking-chair full-cells. Herein, we present a synthetic design to incorporate bridged 2,2'-bipyridinium units, which in their reduced form are known as super-electron-donors, into a polymer structure. By adapting their synthesis, we obtain a hydroxy-functionalized bridged bipyridinium salt with interesting structural features that are determined by molecular symmetry and environmental effects. Incorporation into a linear and cross-linked poly(methacrylate) reduces its electrolyte solubility, enabling its initial electrochemical evaluation in lithium battery half-cells. After testing electrodes with different compositions and screening electrolytes, we demonstrate that these polymers have the potential to function as electrode-active materials, operating at an attractively low potential of 1.8 V vs. Li/Li+. This work highlights the opportunities of low-potential 2,2'-bipyridinium-based polymers and demonstrates how synthetic design strategies can guide the development of novel organic electrode materials, providing a foundation for future research in this field.

The photocatalytic production of green hydrogen constitutes an important step towards sustainable energy storage. An ambitious goal is to couple reductive and oxidative photocatalysis, i.e., the hydrogen-evolution reaction (HER) with water oxidation to achieve overall water splitting. Herein, we explore a pathway towards such coupled processes by using phenothiazines (PTs) as redox mediators (RMs) in HER. In this work, we explored the reductive half reaction utilizing a new hybrid SED-RM architecture with a photocatalytic system consisting of the thiomolybdate cluster (NH4)2[Mo3S13] as catalyst, ascorbic acid as sacrificial electron donor, and [Ru(bpy)3](PF6)2 (bpy = 2,2 '-bipyridine) as photosensitiser (PS). We show that the catalytic performance of the system is improved by a factor of three (increase in turnover number (TON) from 6760 to 20 660 and in turnover frequency (TOF) from 1130 h-1 to 3440 h-1 (for 6h)) with 10H-phenothiazine (PTH) as RM. Stern-Volmer experiments show that PTH and derivatives effectively quench the excited state of [Ru(bpy)3](PF6)2 - independent of pH - enabling photocatalytic HER to be performed at the lower pH of 2.55, where the catalyst is more active due to a higher availability of protons. A near-linear correlation between the emission quenching ability of the PT derivatives and the photocatalytic performance suggests the initial reductive quenching step to be an important kinetic factor in the catalytic cycle. Our study proposes RMs as a strategy to boost the performance of photocatalytic HER systems by mediating efficient electron transfers even at low pH values and paves the way towards coupled reductive and oxidative photocatalysis.

Multivalent metal batteries are attractive options to diversify energy storage options offering higher sustainability, but the high charge density of multivalent ions poses challenges to electrode materials. Organic electrode materials are currently the best-performing candidates, and among them, poly(1,4-anthraquinone) (P14AQ) shows excellent electrochemical properties. This holds in particular for magnesium-ion batteries, where the polymer displays reversible insertion of Mg2+ ions with high cycling stability. The conventional synthesis of P14AQ, however, employs stoichiometric amounts of bis(cycloocta-1,5-diene)nickel(0) (Ni(COD)2), which is an air- and light-sensitive and expensive chemical, and therefore lacks sustainability. Herein a synthetic route to P14AQ is presented that uses only catalytic amounts of dibromobis(triphenylphosphine)nickel(II) (NiBr2(PPh3)2). This route - in addition to being more cost-efficient and less toxic - results in higher yields and polymer molecular weights. A life-cycle assessment (LCA) comparing the new and conventional polymerization methods shows that regarding the environmental impact categories climate change, human toxicity, and cumulative energy demand, the new method brings significant improvement.

Conjugated nanohoops have become highly relevant compounds based on their unique conjugation, structural, optoelectronic, and morphological properties. Recent synthetic efforts have progressed to access more elaborate structures, incorporating two conjugated nanohoops covalently linked by a central linking unit, so-called double nanohoops. Double nanohoops broaden the molecular diversity of strained nanocarbons, and they can show properties exceeding those of single nanohoops. They are often inherently chiral and attractive candidates as chiral-polarized-light emitters, and with two cavities are interesting supramolecular hosts. We herein provide an overview of double nanohoops reported to date, with loops built from only oligo(paraphenylene) units. We categorize their structures into phenylene-linked double nanohoops, double nanohoops with X-linkers, zig-zag double nanohoops, lemniscular double nanohoops, and "other" double nanohoops. We identify four main synthetic pathways that are typically employed, making use of kinked precursors to oligo(paraphenylenes). We individually discuss properties and applications of each double nanohoop. This review shows that creativity and synthetic endurance can furnish unique double nanohoop structures with attractive chiroptical as well as supramolecular properties.

Organic battery electrode materials are key enablers of different postlithium cell chemistries. As a p-type compound with up to two reversible redox processes at relatively high potentials of 3.5 and 4.1 V vs. Li/Li+, phenothiazine is an excellently suited redox-active group. It can easily be functionalized and incorporated into polymeric structures, a prerequisite to obtain insolubility in liquid battery electrolytes. Phenothiazine tends to exhibit π-interactions (π*-π*-interactions) to stabilize its radical cationic form, which can increase the stability of the oxidized form but can also strongly influence its cycling performance as a battery electrode material. In recent years, we investigated a broad range of phenothiazine-based polymers as battery electrode materials, providing insight into the effect of π-interactions on battery performance, leading to design principles for highly functional phenothiazine-based polymers, and enabling the investigation of full cells. We observed that π-interactions are particularly expressed in "mono"-oxidized forms of poly-(3-vinyl-N-methylphenothiazine) (PVMPT) and are enabled in the battery electrode due to the solubility of oxidized PVMPT in many carbonate-based liquid electrolytes. PVMPT dissolves during charge and is redeposited during discharge as a stable film on the positive electrode, however, still retaining half of its charge. This diminishes its available specific capacity to half of the theoretical value. We followed three different strategies to mitigate dissolution and inhibit the formation of π-interactions in order to access the full specific capacity for the one-electron process: Adjusting the electrolyte composition (type and ratio of cyclic vs. linear carbonate), encapsulating PVMPT in highly porous conductive carbons or cross-linking the polymer to X-PVMPT. All three strategies are excellently suited to pursue full-cell concepts using PVMPT or X-PVMPT as positive electrode material. The extent of π-interactions could also be modified by structural changes regarding the polymer backbone (polystyrene or polynorbornene) or exchanging the heteroatom sulfur in phenothiazine by oxygen in phenoxazine. By changing the molecular design and attaching electron-donating methoxy groups to the phenothiazine units, its second redox process can be reversibly enabled, even in carbonate-based electrolytes. Studies by us as well as others provided a selection of high-performing phenothiazine polymers. Their applicability was demonstrated as positive electrode in full cells of different configurations, including dual-ion battery cells using an inorganic or organic negative electrode, anion-rocking-chair cells as examples of all-organic batteries, or even an aluminum battery with a performance exceeding that of aluminum-graphite battery cells. In changing the design concept to conjugated phenothiazine polymers, a higher intrinsic semiconductivity can result, enabling the use of a lesser amount of the conductive carbon additive in the composite electrode. It also provides a handle to alter the optical properties of the polymers, for instance by designing donor-acceptor type conjugated polymers with visible-light absorption, where we demonstrated an application in a photobattery. This Account provides an overview of these findings, also in the context of other literature in the field. It highlights phenothiazine polymers as versatile electrode materials for next-generation batteries.

Pyrene-4,5,9,10-tetraone (PTO) is a building block of significant interest for functional organic materials. Due to the sensitivity of the vicinal diones toward bases and metal-ion chelation, and low solubility, PTO is typically protected as a ketal with ethylene glycol (EtG). Herein, we report the use of propylene glycol (PrG), propane-1,3-diol (PD) or 2,2-dimethylpropane-1,3-diol (DMPD) for its protection. The PrG-protected PTO has a 44-fold increased solubility relative to EtG-protected PTO due the introduced regio- and stereoisomerism. Protection with PD and DMPD surprisingly produced "half" protected PTOs, with maintained protective capabilities, and milder deprotection conditions for PD. All protected PTOs underwent successful functionalization reactions with high yields. Due to its stereocenter, use of PrG-protecting groups gives entry to protected PTOs with chiral-optical properties. This new series of ketal-protecting groups should considerably facilitate the future synthesis of PTO-based materials.

Modern electronic technologies are developing at an impressive pace, shaping today’s societies by making our world more connected, safer, and cleaner. These emerging new electronic devices require battery materials and designs that are inherently flexible and adaptable. However, current flexible battery designs suffer from a lack of stability of the electrode-electrolyte interface. This work presents a new approach to maintain high interfacial stability by covalently binding the electrode and electrolyte components. Strategies for the synthesis of covalent bonded electrochemical interfaces include electrochemical sol-gel deposition[1] of (i) a silane-based precursor on graphite, organic electrodes[2] and aluminum[3], followed by a chemical reaction step with the ionic liquid, and (ii) a mixture of a silylated ionic liquid precursor[4] and tetraethyl orthosilicate (TEOS) in a single step. These electrode-electrolyte composites consist of a very thin and structured layer with low mass transport limitations. The composites are characterized by bendability up to 180 degrees with negligible decrease in ionic conductivity. Fig 1: Proposed mechanism of electrode-electrolyte composites in aluminum batteries and their potential applications References: [1] L. Fang, Q. Q. He, M. J. Zhou, J. P. Zhao, J. M. Hu, Electrochem Commun 2019, 109. [2] G. Studer, A. Schmidt, J. Büttner, M. Schmidt, A. Fischer, I. Krossing, B. Esser, Energy & Environmental Science 2023, 16, 3760-3769. [3] M. Sheffer, A. Groysman, D. Mandler, Corrosion Science 2003, 45, 2893-2904. [4] J. A. Marins, B. G. Soares, Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017, 529, 311-319. Figure 1