An increasing demand for alternative electrolyte systems is emerging to address limitations associated with traditional liquid electrolytes in lithium-ion batteries (LIBs). Hybrid polymer-liquid electrolytes (HEs) combine the merits of solid polymers and liquid electrolytes in a heterogeneous phase-separated system where the polymer phase encapsulates the liquid ion-conducting phase. These electrolytes are synthesized through polymerization-induced phase separation (PIPS), resulting in the formation of a porous three-dimensional polymer network. Carbon black (CB) serves as conductive additive in LIBs electrodes, enhancing electric conductivity and thereby improving the battery performance and lifespan. How CB, already present in conventional electrodes, affects the PIPS process during the formation of HEs for LIBs, focusing on the material interactions and the formed microstructure properties, has been investigated. Addition of CB does not negatively affect the result of PIPS process, and it permits high conversion rate and compatibility with HE at all CB concentrations investigated. Morphological analysis in combination with nuclear magnetic resonance (NMR) and electrochemical impedance spectroscopy (EIS) reveals consistent macroporous and mesoporous structures, indicating the robustness of HEs to CB content variation. Understanding the interaction between CB and HEs during the manufacturing process and the impact of CB on the structural integrity and compatibility of the HE system, aids the integration of HEs with existing electrode materials in practical battery configurations.

Thermally annealed soft carbon and hard carbon samples were investigated by a variety of methods. The ordering of the carbon matrix with increasing heat-treatment temperature was followed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The state of Li ions that can be incorporated in the evolved carbon structures was probed using 7Li NMR spectra and by 7Li NMR spin-relaxation that report the different aspects of order and disorder at the available sites. These latter observables were recorded at different temperatures that permitted separating the various structural and dynamic features (including Li ion diffusion) influencing them. Both the initial structures and their respective structural evolution were shown to be complex. While all observations pointed to an increasing order and an increasing size of domains upon increasing heat-treatment temperature, the change in Li capacity is either non-monotonic (soft carbon) or increasingly diverging from the graphite value (hard carbon). We propose that these, apparently, contradictory trends are partly caused by kinetic limitations. Heat treatment at 2500 degrees C turned the dominating fraction of the soft carbon to essentially graphite with regard to both atomic and electronic structures and long range order, yet also created a minor fraction with a disordered structure that is responsible for the total capacity exceeding that for graphite. Untreated hard carbon permitted metallic clusters, but heat treatment eliminated the necessary sites and/or access to those.

Hypothesis: Aqueous graphene dispersions are usually obtainable by treating the surface of graphene chemically or physically. In these dispersions, the rheological properties (e.g., viscosity) are governed by a direct coupling to the graphene concentration, which limits their applicability. An alternative approach for dispersing graphene is trapping them in a viscoelastic-network formed by a co-dispersed charged fibrous-clay, Sepiolite. Contrary to surface treatment, the rheological properties of these dispersions are set by the clay particles. The rheology of charged-colloidal dispersions is governed by various parameters, including interparticle interactions. Hence, the rheology of the dispersion could be modulated by changing the clay surface charge without compromising the dispersed graphene concentration. Experimental: The surface charge of Sepiolite was modulated either by charge-screening (by NaCl added to the solution) or by surface-charging (by attachment of highly charged ions, e.g., HexaMetaPhosphate, HMP−) and the effect on rheology and graphene concentration was assessed. In particular, loading the dispersion with HMP− yielded low viscosity, storage, and loss moduli (two orders of magnitude lower than the corresponding HMP−-free dispersion) while the graphene concentration was maintained. We demonstrate that by this charge-modulation approach, reaching the rheological requirements of different applications without compromising on graphene concentration is plausible.

Recycling plastics is the key to reaching a sustainable materials economy. Biocatalytic degradation of plastics shows great promise by allowing selective depolymerization of man-made materials into constituent building blocks under mild aqueous conditions. However, insoluble plastics have polymer chains that can reside in different conformations and show compact secondary structures that offer low accessibility for initiating the depolymerization reaction by enzymes. In this work, we overcome these shortcomings by microwave irradiation as a pre-treatment process to deliver powders of polyethylene terephthalate (PET) particles suitable for subsequent biotechnology-assisted plastic degradation by previously generated engineered enzymes. An optimized microwave step resulted in 1400 times higher integral of released terephthalic acid (TPA) from high-performance liquid chromatography (HPLC), compared to original untreated PET bottle. Biocatalytic plastic hydrolysis of substrates originating from PET bottles responded to 78 % yield conversion from 2 h microwave pretreatment and 1 h enzymatic reaction at 30 °C. The increase in activity stems from enhanced substrate accessibility from the microwave step, followed by the administration of designer enzymes capable of accommodating oligomers and shorter chains released in a productive conformation.

Alternative electrolyte systems such as hybrid electrolytes are much sought after to overcome safety issues related to liquid electrolytes in lithium ion batteries (LIBs). Hybrid solid-liquid electrolytes (HEs) like the heterogeneous structural battery electrolyte (SBE) consist of two discrete co-existing phases prepared by polymerization-induced phase separation: one solid polymer phase providing mechanical integrity and the other one a percolating liquid ion-conducting phase. The present work investigates the ion and the solvent mobility in a series of HEs using morphological, electrochemical impedance and NMR spectroscopic methods. All the dried HEs exhibit a porous structure with a broad pore size distribution stretching down to <10 nm diameter. Penetration of the individual components of the solution, that is the ions and the solvent, in the solid polymer phase is demonstrated. Yet, it is the pores that are the main ion conduction channels in the liquid-saturated HEs and, in general, translational mobility is strongly dependent on the volume fraction and size of the pores and, thereby, on the initial liquid electrolyte content. We also observe that the translational mobility of solvent and the ions vary differently with the pore volume fraction. This finding is explained by the presence of small mesopores where the mobility strongly depends on the specific interactions of the molecular constituent with the pore wall. These interactions are inferred to be stronger for the EC/PC solvent than for the ions. This study shows how the morphology and the chemical composition of HEs affect the ionic and molecular transport in the system.

Conditions such as the temperature and pressure experienced by lithium-ion battery components are dependent oncell geometry and can vary widely within a large cell. The resulting uneven degradation is challenging to study at thefull cell level but can be revealed upon disassembly and post mortem analysis. In this work, we report localizedlithium plating in automotive-grade, prismatic lithium-ion cells, also under cycling conditions generally consideredto be mild (e.g., 5–65 %SOC, 23 ◦C, 0.5C cycle rate). Dead lithium content is quantified using 7Li nuclear magneticresonance spectroscopy in both electrode and separator samples, corresponding to substantial capacity fade(26–46%) of the full cells. Severe lithium plating is typically initiated in regions near the positive tab, in which boththe separators and negative electrodes are ultimately deactivated. High pressure arises during cycling, and wepropose a deactivation mechanism based on high local stress due to electrode expansion and external constraint.Further, we develop a model to demonstrate that component deactivation can result in lithium plating even undermild cycling conditions. Notably, components harvested from regions with no detected lithium plating maintainedadequate electrochemical performance.

In the cellulose scientific community, hydrogen bonding is often used as the explanation for a large variety of phenomena and properties related to cellulose and cellulose based materials. Yet, hydrogen bonding is just one of several molecular interactions and furthermore is both relatively weak and sensitive to the environment. In this review we present a comprehensive examination of the scientific literature in the area, with focus on theory and molecular simulation, and conclude that the relative importance of hydrogen bonding has been, and still is, frequently exaggerated.

Due to the steric effects imposed by bulky polymers, the formation of catalytically competent enzyme and substrate conformations is critical in the biodegradation of plastics. In poly(ethylene terephthalate) (PET), the backbone adopts different conformations, gauche and trans, coexisting to different extents in amorphous and crystalline regions. However, which conformation is susceptible to biodegradation and the extent of enzyme and substrate conformational changes required for expedient catalysis remain poorly understood. To overcome this obstacle, we utilized molecular dynamics simulations, docking, and enzyme engineering in concert with high-resolution microscopy imaging and solid-state nuclear magnetic resonance (NMR) to demonstrate the importance of conformational selection in biocatalytic plastic hydrolysis. Our results demonstrate how single-amino acid substitutions in Ideonella sakaiensis PETase can alter its conformational landscape, significantly affecting the relative abundance of productive ground-state structures ready to bind discrete substrate conformers. We experimentally show how an enzyme binds to plastic and provide a model for key residues involved in the recognition of gauche and trans conformations supported by in silico simulations. We demonstrate how enzyme engineering can be used to create a trans-selective variant, resulting in higher activity when combined with an all-trans PET-derived oligomeric substrate, stemming from both increased accessibility and conformational preference. Our work cements the importance of matching enzyme and substrate conformations in plastic hydrolysis, and we show that also the noncanonical trans conformation in PET is conducive for degradation. Understanding the contribution of enzyme and substrate conformations to biocatalytic plastic degradation could facilitate the generation of designer enzymes with increased performance.

Exploration of efficient water oxidation catalysts (WOCs) is the primary challenge in conversion of renewable energy into fuels. Here we report a molecularly well-defined heterogeneous WOC with Aza-fused, pi-conjugated, microporous polymer (Aza-CMP) coordinated single cobalt sites (Aza-CMP-Co). The single cobalt sites in Aza-CMP-Co exhibited superior activity under alkaline and near-neutral conditions. Moreover, the molecular nature of the isolated catalytic sites makes Aza-CMP-Co a reliable model for studying the heterogeneous water oxidation mechanism. By a combination of experimental and theoretical results, a pH-dependent nucleophilic attack pathway for O-O bond formation was proposed. Under alkaline conditions, the intramolecular hydroxyl nucleophilic attack (IHNA) process with which the adjacent -OH group nucleophilically attacks Co4+=O was identified as the rate-determining step. This process leads to lower activation energy and accelerated kinetics than those of the intermolecular water nucleophilic attack (WNA) pathway. This study provides significant insights into the crucial function of electrolyte pH in water oxidation catalysis and enhancement of water oxidation activity by regulation of the IHNA pathway.

We investigate hard carbon fibers in different states of charge by a combination of 7Li-NMR and 2D-XRD. In particular, we record the quadrupole-split 7Li-NMR spectra and 7Li longitudinal relaxation over a wide temperature range, and determine lithium self-diffusion both parallel and perpendicular to the fiber axis. Recording the temperature dependence permits us to interpret the presence of motional averaging of spin couplings for mobile Li. The joint analysis shows that at low Li content, Li occupies sites that lack ordered coordination and delocalized electrons and are collected in disordered spatial domains. Upon increasing the Li content, ordered sites collected in ordered domains become populated. Both disordered and ordered domains have a high inherent heterogeneity with a typical spatial extension of a few nanometers. The disordered domains exhibit a continuous topology that permits unhindered diffusion within it. At high Li content we also observe the presence of very small (∼nm) particles of metallic lithium. The joint analysis of XRD in combination with diffusion anisotropy, and anisotropy from the 7Li-NMR spectrum (with samples oriented differently with regard to the applied magnetic field), shows that the mesoscopic structure is made by ordered domains arranged in a cylindrically rolled-up manner with the mesoscopic axis parallel to the fiber axis.