Non-equilibrium metal oxides via reconversion chemistry in lithium-ion batteries

The Alkynyl π Bond of sp-C Enhanced Rapid, Reversible Li-C Coupling to Accelerate Reaction Kinetics of Lithium Ions

Graphdiyne (GDY) is a promising anode for rechargeable batteries with high capacity, outstanding cyclic stability, and low diffusion energy. The unique structure of GDY endows distinctive mechanisms for metal-ion storage, and it is of great significance to further visualize the complex reaction kinetics of the redox process. Here, we systematically tracked the reaction kinetics and provided mechanistic insights into the lithium ions in the GDY to reveal the feature of the cation-π effect. It has been demonstrated that, unlike only one π bond in sp2-C, π electrons provided by one of the two alkynyl π bonds in sp-C can achieve proper interaction and speedy capture of lithium ions; thus, reversible Li-C coupling can be formed between electron-rich sp-C and lithium ions. In addition to interlayer intercalation in sp2-C regions, nanopores filling triangular-like cavities composed of highly conjugated sp-C contribute to the major capacity in flat voltage plateau regions. Therefore, a capture/pores filling-intercalation hybrid mechanism can be found in GDY. The coexistence of sp and sp2 carbon enables GDY electrodes with rapid Li+ diffusion, high capacity of over 1435 mAh g-1, extraordinary rate capability, and cyclic stability for more than 10000 cycles at 10A g-1. These results provide guidance for developing advanced carbon electrodes with optimized reaction kinetics for rechargeable batteries.

Design and Reaction Mechanism of Rechargeable Lithium-Carbon Fluoride Battery

Recharging primary batteries is of great importance for increasing the energy density of energy storage systems to power electric aircraft and beyond. Carbon fluoride (CFx) cathodes are characterized by high specific capacity and energy density (865 mAh g-1 and 2180 Wh kg-1, respectively). Preventing the crystallization of LiF with an intermediate and lowering the energy barrier from LiF to CFx is expected to render the Li/CFx battery reversible. In this study, taking the advantage of a high-voltage-stable all-fluorinated electrolyte containing the boron-based anion receptor tris(trimethylsilyl)borate (TMSB), a rechargeable Li/CFx battery was realized with a reversible capacity of 465.9 mAh g-1 and an energy density of 1183.9 Wh kg-1, approximately 53% of that in the first discharge. After the first discharge, the charge-discharge profile featured rechargeable characteristics. In situ X-ray diffraction, ex situ soft X-ray absorption spectroscopy, pair distribution function analysis, and other measurements confirmed the generation and decomposition of Li-F and C-F bonds during cycling. Density functional theory calculations and nuclear magnetic resonance spectroscopy confirmed that TMSB serves as an anion carrier through the generation of a [TMSB-F]- complex, facilitating the conversion reactions during cycling. This study demonstrated a facile and low-cost approach for realizing high-energy-density, reversible Li/CFx batteries.

Inflammatory bowel disease is associated with an increase in the incidence of multiple sclerosis: a retrospective cohort study of 24,934 patients

BACKGROUND

Recent data suggest a potential pathophysiological link between inflammatory bowel disease (IBD) and multiple sclerosis (MS), two immune-mediated diseases both of which can have a significant impact on patients' quality of life. In the present manuscript, we investigate the association between IBD and MS in a German cohort of general practice patients. These results may have important implications for the screening and management of patients with IBD, as well as for further research into the pathophysiological mechanisms underlying both disorders.

METHODS

4,934 individuals with IBD (11,140 with Crohn's disease (CD) and 13,794 with ulcerative colitis (UC)) as well as 24,934 propensity score matched individuals without IBD were identified from the Disease Analyzer database (IQVIA). A subsequent diagnosis of MS was analyzed as a function of IBD using Cox regression models.

RESULTS

After 10 years of follow-up, 0.9% and 0.7% of CD and UC patients but only 0.5% and 0.3% of matched non-IBD pairs were diagnosed with MS, respectively (pCD = 0.002 and pUC < 0.001). Both CD (HR: 2.09; 95% CI 1.28-3.39) and UC (HR: 2.35; 95% CI 1.47-3.78) were significantly associated with a subsequent MS diagnosis. Subgroup analysis revealed that the association between both CD and UC and MS was more pronounced among male patients.

CONCLUSION

The results of our analysis suggest a notable association between IBD and a subsequent MS diagnosis. These findings warrant further pathophysiological investigation and may have clinical implications for the screening of IBD patients in the future.

Real-time tracking of electron transfer at catalytically active interfaces in lithium-ion batteries

Transition metals and related compounds are known to exhibit high catalytic activities in various electrochemical reactions thanks to their intriguing electronic structures. What is lesser known is their unique role in storing and transferring electrons in battery electrodes which undergo additional solid-state conversion reactions and exhibit substantially large extra capacities. Here, a full dynamic picture depicting the generation and evolution of electrochemical interfaces in the presence of metallic nanoparticles is revealed in a model CoCO3/Li battery via an in situ magnetometry technique. Beyond the conventional reduction to a Li2CO3/Co mixture under battery operation, further decomposition of Li2CO3 is realized by releasing interfacially stored electrons from its adjacent Co nanoparticles, whose subtle variation in the electronic structure during this charge transfer process has been monitored in real time. The findings in this work may not only inspire future development of advanced electrode materials for next-generation energy storage devices but also open up opportunities in achieving in situ monitoring of important electrocatalytic processes in many energy conversion and storage systems.

Boosting Solid-State Reconversion Reactivity to Mitigate Lithium Trapping for High Initial Coulombic Efficiency

An initial Coulombic efficiency (ICE) higher than 90% is crucial for industrial lithium-ion batteries, but numerous electrode materials are not standards compliant. Lithium trapping, due to i) incomplete solid-state reaction of Li+ generation and ii) sluggish Li+ diffusion, undermines ICE in high-capacity electrodes (e.g., conversion-type electrodes). Current approaches mitigating lithium trapping emphasize ii) nanoscaling (<50 nm) to minimize Li+ diffusion distance, followed by severe solid electrolyte interphase formation and inferior volumetric energy density. Herein, this work accentuates i) instead, to demonstrate that the lithium trapping can be mitigated by boosting the solid-state reaction reactivity. As a proof-of-concept, ternary LiFeO2 anodes, whose discharged products contain highly reactive vacancy-rich Fe nanoparticles, can alleviate lithium trapping and enable a remarkable average ICE of ≈92.77%, much higher than binary Fe2 O3 anodes (≈75.19%). Synchrotron-based techniques and theoretical simulations reveal that the solid-state reconversion reaction for Li+ generation between Fe and Li2 O can be effectively promoted by the Fe-vacancy-rich local chemical environment. The superior ICE is further demonstrated by assembled pouch cells. This work proposes a novel paradigm of regulating intrinsic solid-state chemistry to ameliorate electrochemical performance and facilitate industrial applications of various advanced electrode materials.

Revealing the effect of LiOH on forming a SEI using a Co magnetic "probe"

The solid-electrolyte-interphase (SEI) plays a critical role in lithium-ion batteries (LIBs) because of its important influence on electrochemical performance, such as cycle stability, coulombic efficiency, etc. Although LiOH has been recognized as a key component of the SEI, its influence on the SEI and electrochemical performance has not been well clarified due to the difficulty in precisely controlling the LiOH content and characterize the detailed interface reactions. Here, a gradual change of LiOH content is realized by different reduction schemes among Co(OH)2, CoOOH and CoO. With reduced Co nanoparticles as magnetic "probes", SEI characterization is achieved by operando magnetometry. By combining comprehensive characterization and theoretical calculations, it is verified that LiOH leads to a composition transformation from lithium ethylene di-carbonate (LEDC) to lithium ethylene mono-carbonate (LEMC) in the SEI and ultimately results in capacity decay. This work unfolds the detailed SEI reaction scenario involving LiOH, provides new insights into the influence of SEI composition, and has value for the co-development between the electrode materials and electrolyte.

Covalent Organic Framework Based Crosslinked Porous Microcapsules for Enzymatic Catalysis

The design of porous microcapsules with selective mass transfer and mechanical robustness for enzyme encapsulation is highly desired for biocatalysis, yet the construction remains challenging. Herein, we report the facile fabrication of porous microcapsules by assembling covalent organic framework (COF) spheres at the interfaces of emulsion droplets followed by interparticle crosslinking. The COF microcapsules could offer an enclosed aqueous environment for enzymes, with size-selective porous shells that allow for the fast diffusion of substrates and products while excluding larger molecules such as protease. Crosslinking of COF spheres not only enhances the structural stability of capsules but also imparts enrichment effects. The enzymes encased in the COF microcapsules show enhanced activity and durability in organic media as verified in both batch reaction and continuous-flow reaction. The COF microcapsules offer a promising platform for the encapsulation of biomacromolecules.

Hofmann Ni-Pz-Ni Metal-Organic Frameworks Decorated by Graphene Oxide Enabling Lithium Storage with Pseudocapacitance Contribution

Hofmann metal-organic frameworks (MOFs) are a variety of hybrid inorganic-organic polymers with a stable framework, plentiful adjustable pore size, and redox active sites, which display great application potential in energy storage. Unfortunately, the rapid and uncontrollable rate of coordination reaction results in a large size and an anomalous morphology, and the low electrical conductivity also severely limited further development, so there are few literature studies on Hofmann MOFs as anode materials for rechargeable batteries. Introducing graphene oxide can not only greatly facilitate the formation of a continuous conductive network but also effectively anchor and disperse MOF particles by utilizing the two-dimensional planar structure, thus reducing the sizes and agglomeration of particles. In this work, various mass ratios of graphene oxide with 3D Hofmann Ni-Pz-Ni MOFs were prepared via a simple one-pot solvothermal method. Benefiting from the gradually increasing capacitance characteristic during the continuous charge/discharge process, the Ni-Pz-Ni/GO-20% electrode exhibits a great reversible capacity of 896.1 mAh g^-1 after 100 cycles and excellent rate capability, which will lay a theoretical foundation for exploring the high-performance Hofmann MOFs in the future.

Dual fluorination of polymer electrolyte and conversion-type cathode for high-capacity all-solid-state lithium metal batteries

All-solid-state batteries are appealing electrochemical energy storage devices because of their high energy content and safety. However, their practical development is hindered by inadequate cycling performances due to poor reaction reversibility, electrolyte thickening and electrode passivation. Here, to circumvent these issues, we propose a fluorination strategy for the positive electrode and solid polymeric electrolyte. We develop thin laminated all-solid-state Li||FeF3 lab-scale cells capable of delivering an initial specific discharge capacity of about 600 mAh/g at 700 mA/g and a final capacity of about 200 mAh/g after 900 cycles at 60 °C. We demonstrate that the polymer electrolyte containing AlF3 particles enables a Li-ion transference number of 0.67 at 60 °C. The fluorinated polymeric solid electrolyte favours the formation of ionically conductive components in the Li metal electrode's solid electrolyte interphase, also hindering dendritic growth. Furthermore, the F-rich solid electrolyte facilitates the Li-ion storage reversibility of the FeF3-based positive electrode and decreases the interfacial resistances and polarizations at both electrodes.

A 3D structure C/Si/ZnCo2O4/CC anode for flexible lithium-ion batteries with high capacity and fast charging ability

ZnCo₂O₄ has attracted extensive attention as a bimetallic transition metal oxide anode material for lithium-ion batteries (LIBs) with high capacity. However, there is still a long way to go to meet the increasing demand for commercial batteries due to their modest conductivity and unobtrusive cycling stability. The use of finely controlled nanostructures and combination with other anode materials are the two main ways to improve the battery performance of ZnCo₂O₄. Herein, ZnCo₂O₄ (ZCO) nanosheets were in situ grown on carbon cloth (CC) through a facile solution method. Si was coated onto the ZCO nanosheet arrays by the magnetron sputtering method (SCZO/CC) to acheive the capacity increase. A layer of C was further coated onto SZCO/CC to improve the electrical conductivity of the whole electrode and to protect the SZCO nanostructure. The obtained CSZCO/CC electrode exhibits a high reversible areal capacity of 1.16 mA h cm^-2 at 5 mA cm^-2 after 500 cycles. At an ultra-high current density of 10 mA cm^-2, the CSZCO/CC electrode can still present a capacity of 0.38 mA h cm^-2 and maintain a capacity retention of 88.4% for 2000 cycles. In situ Raman spectroscopy was used to study the relationship between the electrochemical performance and structure of the electrode materials. The carbon cloth was found to have contributed a nonnegligible part of the capacity of the electrode.

Multivariate analysis of disorder in metal-organic frameworks

The rational design of disordered frameworks is an appealing route to target functional materials. However, intentional realisation of such materials relies on our ability to readily characterise and quantify structural disorder. Here, we use multivariate analysis of pair distribution functions to fingerprint and quantify the disorder within a series of compositionally identical metal–organic frameworks, possessing different crystalline, disordered, and amorphous structures. We find this approach can provide powerful insight into the kinetics and mechanism of structural collapse that links these materials. Our methodology is also extended to a very different system, namely the melting of a zeolitic imidazolate framework, to demonstrate the potential generality of this approach across many areas of disordered structural chemistry.

Structural disorder in materials is challenging to characterise. Here, the authors use multivariate analysis of atomic pair distribution functions to study structural collapse and melting of metal–organic frameworks, revealing powerful mechanistic and kinetic insight.

Entropy Stabilization Effect and Oxygen Vacancies Enabling Spinel Oxide Highly Reversible Lithium-Ion Storage

High-entropy materials are an emerging kind of solid-solution material, demonstrating various exotic physicochemical properties, that have led to increased research activity as electrode materials for rechargeable batteries. Here, a kind of high-entropy spinel oxide, (Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)₃O₄ (CCFMNO), was successfully fabricated via a solution combustion method. Due to the entropy stabilization effect and the intrinsic high mechanical strength of CCFMNO, an excellent cycling stability can be achieved. In addition, the fruitful oxygen vacancies in CCFMNO increase extra Li-ion accommodation sites, accelerating electronic conductivity and promoting Li-ion migration, thus enabling a high rate performance of 428 mAh g^-1 at a high current density of 10 A g^-1. More impressively, CCFMNO electrodes demonstrate excellent temperature adaptability with no capacity degeneration after 50 cycles at 0, 25, and 50 °C. Meanwhile, a full cell based on a CCFMNO anode and LiFePO₄ cathode delivers an impressive high energy density of 372 Wh kg^-1. All these impressive lithium storage performances strongly suggest that CCFMNO could be a promising anode material for lithium-ion batteries.

Recovering local structure information from high-pressure total scattering experiments

High pressure is a powerful thermodynamic tool for exploring the structure and the phase behaviour of the crystalline state, and is now widely used in conventional crystallographic measurements. High-pressure local structure measurements using neutron diffraction have, thus far, been limited by the presence of a strongly scattering, perdeuterated, pressure-transmitting medium (PTM), the signal from which contaminates the resulting pair distribution functions (PDFs). Here, a method is reported for subtracting the pairwise correlations of the commonly used 4:1 methanol:ethanol PTM from neutron PDFs obtained under hydro-static compression. The method applies a molecular-dynamics-informed empirical correction and a non-negative matrix factorization algorithm to recover the PDF of the pure sample. Proof of principle is demonstrated, producing corrected high-pressure PDFs of simple crystalline materials, Ni and MgO, and benchmarking these against simulated data from the average structure. Finally, the first local structure determination of α-quartz under hydro-static pressure is presented, extracting compression behaviour of the real-space structure.

Extracting interface correlations from the pair distribution function of composite materials

Using a non-negative matrix factorisation (NMF) approach, we show how the pair distribution function (PDF) of complex mixtures can be deconvolved into the contributions from the individual phase components and also the interface between phases. Our focus is on the model system Fe∥Fe3O4. We establish proof-of-concept using idealised PDF data generated from established theory-driven models of the Fe∥Fe3O4 interface. Using X-ray total scattering measurements for corroded Fe samples, and employing our newly-developed NMF analysis, we extract the experimental interface PDF ('iPDF') for this same system. We find excellent agreement between theory and experiment. The implications of our results in the broader context of interface characterisation for complex functional materials are discussed.

Electrochemical Lithiation/Delithiation of ZnO in 3D-Structured Electrodes: Elucidating the Mechanism and the Solid Electrolyte Interphase Formation

Conversion/alloy active materials, such as ZnO, are one of the most promising candidates to replace graphite anodes in lithium-ion batteries. Besides a high specific capacity (q_ZnO = 987 mAh g^-1), ZnO offers a high lithium-ion diffusion and fast reaction kinetics, leading to a high-rate capability, which is required for the intended fast charging of battery electric vehicles. However, lithium-ion storage in ZnO is accompanied by the formation of lithium-rich solid electrolyte interphase (SEI) layers, immense volume expansion, and a large voltage hysteresis. Nonetheless, ZnO is appealing as an anode material for lithium-ion batteries and is investigated intensively. Surprisingly, the conclusions reported on the reaction mechanism are contradictory and the formation and composition of the SEI are addressed in only a few works. In this work, we investigate lithiation, delithiation, and SEI formation with ZnO in ether-based electrolytes for the first time reported in the literature. The combination of operando and ex situ experiments (cyclic voltammetry, X-ray photoelectron spectroscopy, X-ray diffraction, coupled gas chromatography and mass spectrometry, differential electrochemical mass spectrometry, and scanning electron microscopy) clarifies the misunderstanding of the reaction mechanism. We evidence that the conversion and alloy reaction take place simultaneously inside the bulk of the electrode. Furthermore, we show that a two-layered SEI is formed on the surface. The SEI is decomposed reversibly upon cycling. In the end, we address the issue of the volume expansion and associated capacity fading by incorporating ZnO into a mesoporous carbon network. This approach reduces the capacity fading and yields cells with a specific capacity of above 500 mAh g^-1 after 150 cycles.

Data-driven machine learning model for the prediction of oxygen vacancy formation energy of metal oxide materials

Metal oxides are widely used in the fields of chemistry, physics and materials science. Oxygen vacancy formation energy is a key parameter to describe the chemical, mechanical, and thermodynamic properties of metal oxides. How to acquire quickly and accurately oxygen vacancy formation energy remains a challenge for both experimental and theoretical researchers. Herein, we propose a machine learning model for the prediction of oxygen vacancy formation energy via data-driven analysis and the definition of simple descriptors. Starting with the database containing oxygen vacancy formation energies for 1750 metal oxides with enough structural diversity, new descriptors that effectively avoid the defects of molecular fingerprints, molecular graphic descriptors and site descriptors are defined. The descriptors have obvious physical meanings and wide practicability. Multiple linear regression analysis is then used to screen important features for machine learning model development, and two strongly associated features are obtained. The selected descriptors are used as input for the training of 21 machine learning models to select and develop the most accurate machine learning model. Finally, it is shown that the least squares support vector regression method exhibits the best performance for accurate prediction of the targeted oxygen vacancy formation energy through systematic error analysis, and the prediction accuracy is also verified by the external dataset. Our work establishes a novel and simple computational approach for accurate prediction of the oxygen vacancy formation energy of metal oxides and highlights the availability of data-driven analysis for metal oxide material research.