High Loading Density Research Articles

A Systematic Approach for Estimating Colloidal Particle Adsorption Model Parameters

The estimation of ion- exchange chromatography model parameters is crucial to enable efficient model-assisted biopharmaceutical downstream process development. Model calibration methods can be hindered by model limitations combined with parameter correlations, leading to time-consuming repeated parameter estimations. While Steric Mass Action isotherm estimation methods exist, there is a need for a systematic approach to estimate model parameters for an emerging Colloidal Particle Adsorption (CPA) model proposed by Briskot et al. This study presents a novel strategy that addresses this challenge, offering significant improvements.Through a parameter sensitivity analysis, we identified key levers for improved CPA parameter estimation, enabling the prediction of elution behavior for low and high load densities in gradient and step elution mode. This analysis also revealed the correlation structure of parameters, allowing the establishment of a minimalized experimental data set for parameter estimation, by using one breakthrough, a high load and three low load density gradient elution experiments. Our workflow leverages a surrogate-assisted global-optimization tool, minimizing computationally expensive function evaluations during parameter fitting. Furthermore, we employed a customized objective function, specifically adapted to the model structure and sensitivity results, to enhance the solver's performance.Our strategy was tested on three model proteins with molecular weights of approximately 50, 150 and 200 kDa using a strong cation exchange Poros 50 HS resin. Our final approach enabled high throughput CPA model calibration for single components. The resulting CPA models were able to describe non-binding protein-pulses, low and high-loaded gradient elution, break through, as well as isocratic elution experiments.

Influence of Loading Density and Gender on the Welfare and Meat Quality of Horses During Transport for Slaughter.

The aim of this study was to determine the effects of loading density and gender on blood welfare indicators, carcass bruises and horsemeat quality. Data were collected from twelve transports of 89 slaughter horses originating from the same collection centre. The transportation of slaughter horses at high loading densities (>200 kg/m2), especially stallions, resulted in increased levels of lactate (p = 0.021), glucose (p < 0.0001), ceruloplasmin (p < 0.0001) and AOPP (p < 0.0001), but lower GSH levels (p < 0.0001). Compared to stallions and mares, geldings subjected to high loading density (>200 kg/m2) during transport had lower levels of the aforementioned blood metabolites. In addition, stallions exposed to a high load density (>200 kg/m2) had the highest frequency of severe (p = 0.0002), large (p < 0.0001) and circular (p = 0.0001) carcass bruises, which were predominantly located on the abdominal (p = 0.0056) and thoracic (p = 0.0004) wall. In contrast, a higher percentage (p < 0.0001) of undamaged carcasses was found in slaughter horses exposed to a low loading density (≤200 kg/m2) during transport. Stallions exposed to high loading densities (>200 kg/m2) during transport had the highest initial pH (p < 0.0001) and ultimate pH (p = 0.005) in terms of m. longissimus lumborum and redness (p = 0.017), but the lowest drip loss (p = 0.050) and lightness (p < 0.0001), which, consequently, led to the highest (p = 0.0045) proportion of DFD-like defects in the meat quality. In conclusion, the results of this study showed that high loading densities (>200 kg/m2), regardless of gender, negatively affect horse welfare during transport. In addition, stallions were more sensitive to poor pre-slaughter conditions and produced the lowest meat quality, while geldings were the most resistant. To determine the optimal transport density, further research is needed to determine the effects of different loading densities on the behaviour, physiology, carcass and meat quality of slaughter horses.

Hierarchical magneto-colorimetric labels for immediate lateral flow immunoassay of chlorothalonil residues

Quantitative detection of pesticide residues in food and environmental samples using an improved lateral flow immunoassay (LFIA) is of considerable importance for real-time analysis. This paper proposes a highly sensitive LFIA platform based on a hierarchical magneto-colorimetric compact. This compact serves as both the target magnetic enrichment substrate and a photosensitive label. Initially, a large porous dendritic silica template is prepared and doped with superparamagnetic ferric oxide nanoparticles (Fe3O4 NPs) and colloidal gold nanoparticles (AuNPs) at high densities within its vertical channels. The sequential assembly of central–radial channels allow for the three-dimensional integration of these two components, enabling independent control of their discrete functions without mutual interference. Following alkyl organosilicon encapsulation and silica sealing, the composite spheres are then applied in LFIA to detect chlorothalonil residues. Fe3O4 NPs enhance the binding efficiency to target analytes, while AuNPs amplify the signal, leveraging their high loading densities and robust optical properties. The developed LFIA platform exhibited a detection limit of 0.34 ng/mL for chlorothalonil and a linear range of 0.0085–824 ng/mL. The recoveries varied between 85.1 % and 103.1 %, and the relative standard deviations were 1.25%–8.84 %. This LFIA approach demonstrates high sensitivity, specificity, reproducibility and flexible detection modes, making it highly suitable for the on-site monitoring of pesticide residues.

Rapid, efficient and highly selective separation and enrichment of glycoprotein by surface-imprinted MOF nanoparticles loaded with high-density boric acid

Usually, glycoproteins are related to diseases or physiological processes; however, a serious challenge remains in realizing their highly specific recognition and enrichment via an imprinting strategy owing to their large molecular size, water solubility and high flexibility. Herein, we reported novel molecularly imprinted polymers based on a metal–organic framework (MOF) material, which achieved the specific enrichment of the target glycoprotein ovalbumin (OVA) by combining a boronate affinity strategy with directional surface imprinting technique. The MOF skeleton has a large specific surface area, thus resulting in a high loading density for the boric acid group (4.66 %) and a satisfactory adsorption capacity (482.56 mg/g). Boronate affinity strategy and the surface imprinting technique resulted in a high specificity of the target glycoprotein. Surface imprinting led to imprinting sites located on the shallow surface of nanoparticles, thus resulting in a rapid kinetic adsorption equilibrium (20 min). And the presence of an acyl group on phenylboronic acid led to the best enrichment effect under physiological pH (7.4). Furthermore, OVA in the real egg white was successfully analyzed, which confirmed the universality of this strategy.

Significance of homogeneous conductive network in layered oxide-based cathode for high-rate capability of electric vehicle batteries

The trade-off between battery energy density and power performance is the core problem that puzzles the development of electric vehicles (EVs). Although intensive researches are performed to explore active materials with good dynamics, the heterogeneous reactivity has been identified as an important cause for inferior capability and early death, especially for electrodes characterized with high areal loading and high compacted density. Herein, the heterogeneity and its origination of layered oxide-based (LiNixCoyMn1-x-yO2, NCM) electrodes at high C-rate are investigated through operando X-ray diffraction and ex-situ time-of-flight secondary ion mass spectrometry probe. By introducing Li3V2(PO4)3@G composite as a mixed conductor additive, the heterogeneous reactivity intro-particles are successfully mitigated, enabling NCM electrodes with both high rate capability, high energy density and high cyclability. In detail, the capacity retention at 20C is increased by 2.3 times, and the capacity retention at 0.5C after 160 full cycles is increased by 1.6 times, without electrolyte additive or material modification. This study demonstrates the significance of the homogeneous electronic/ionic transportation network to the rate capability and lifetime of an electrode, and discloses the design strategy of multifunctional additives to enhance the power density of a battery by maximizing the utility of the active particles.

Characterization of Respirable Coal Mine Dust Recovered from Fibrous Polyvinyl Chloride Filters by Scanning Electron Microscopy

The characterization of respirable dust on the basis of constituent fractions and particle sizes is increasingly of concern for evaluating exposure hazards. For high-resolution particle analysis, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) can be an effective tool. However, it requires particles to be deposited on a smooth, uniform substrate such as a polycarbonate (PC) filter for optimal results. While direct sampling onto PC is possible, this is not the standard approach in many situations. For example, in coal mines, respirable dust samples have typically been collected onto polyvinyl chloride (PVC) filters because they are intended for gravimetric and/or infrared spectroscopy analysis. Such fibrous substrates are not ideal for SEM-EDX (or other microscopy), but an effective method to recover and redeposit the dust particles could render such samples suitable for the additional analysis. Here, we present a simple method and compare SEM-EDX results for paired samples analyzed directly on PC and following recovery from PVC and redeposition on PC. Both laboratory-generated dust samples (n = 10 pairs) and field samples of respirable coal mine dust (n = 44 pairs) are included in this study. Although some changes in particle size distributions were observed between samples analyzed directly and those that were recovered and redeposited prior to analysis, the results indicate the dust recovery method generally yields a representative sample in terms of mineral constituents. That said, results also highlighted the effects of high particle loading density on individual particle analysis. Considering all sample pairs, those with similar loading density between the directly analyzed and recovered sample tended to exhibit similar mineralogy distributions. This was generally the case for the lab-generated sample pairs, and the Freeman-Halton exact test of independence indicated that the samples in just three (of 10) pairs were in disagreement in terms of their mineralogy distributions. On the other hand, for the field samples, the directly analyzed sample often had higher loading density than the recovered sample; and the Freeman-Halton test showed that 25 (of 44) pairs were in disagreement. However, the effect of possible particle agglomeration on the directly analyzed samples cannot be ruled out—and exploration of this factor was beyond the scope of the current study.

Multifunctional tri-layer aramid nanofiber composite separators for high-energy-density lithium-sulfur batteries

Lithium-sulfur (Li-S) battery has attracted much attention due to their high theoretical energy density. However, severe shuttling effect, sluggish reaction kinetics and uncontrolled dendrite formation of Li anode greatly deter their practical applications. Different to conventional separator engineering strategies that are always focused on surface coating of functional interlayer on commercial polyolefin separators, herein, we proposed a structural engineering tactic by rationally tuning the porous structure and composition of the p-aramid nanofiber (ANF) composite separator to address simultaneously the above problems. A two-step film-casting process combined with a phase inversion approach was developed to fabricate a multifunctional tri-layer ANF composite separator. This innovative separator was especially engineered to comprise a conductive and catalytic NiFe2O4 modified multi-walled carbon nanotubes/ANF layer for rapid and efficient conversion of lithium polysulfides, a microporous ANF layer for fast ion transport, and a dense nanoporous ANF layer for lithium dendrite inhibition. This tri-layer ANF-based separator possessed high porosity, excellent thermal stability, and superb electrolyte wettability. Batteries with the tri-layer ANF- based separator exhibited outstanding cyclic stability with high capacity of >3 mAh cm−2 at high sulfur loading (4 mg cm−2) and high current density (4 mA cm−2). This work opens up new opportunities for design of functional separators based on high performance polymers using the structural engineering strategy.

Synthesis and characterization of a julolidine-based electro-optic molecular glass.

Organic electro-optic (EO) materials have recently gained considerable attention owing to their advantages compared to inorganic EO materials. Among different kinds of organic EO materials, organic EO molecular glass exhibits desired prospect because of its high chromophore loading density and large macroscopic EO activity. The objective of this study is to design and synthesize a novel organic EO molecular glass JMG utilizing julolidine moiety as the electron donor, thiophene moiety as the conjugated bridge, trifluoromethyl substituted tricyanofuran derivate (Ph-CF3-TCF) as the electron acceptor. The JMG's structure was characterized through NMR and HRMS. The photophysical property, glass transition temperature, first hyperpolarizability (β) and dipole moment (μ) of JMG were determined through UV-vis spectra, DSC test and DFT calculation. JMG's Tg reached to 79 °C and it can form high-quality optical film. The theoretical calculation shows that the first hyperpolarizability (β) and dipole moment (μ) of JMG were calculated to 730×10-30 esu and 21.898 D. After connecting poling with the poling voltage of 49 V/μm at 90 ℃for 10 min, the highest EO coefficient (r33) of the poled JMG films reached to 147 pm/V. A novel julolidine-based NLO chromophore with two tert-butyldiphenylsilyl (TBDPS) groups was successfully prepared and characterized. TBDPS group is introduced as the film-forming group, and it also plays the role of isolation group, which can suppress the electrostatic interaction between chromophores, improve the poling efficiency and further enhance the EO activity. The excellent performances endow JMG with potential applications in device fabrication.

Modeling of a Bioengineered Immunomodulating Microenvironment for Cell Therapy.

Cell delivery and encapsulation platforms are under development for the treatment of Type 1 Diabetes among other diseases. For effective cell engraftment, these platforms require establishing an immune-protected microenvironment as well as adequate vascularization and oxygen supply to meet the metabolic demands of the therapeutic cells. Current platforms rely on 1) immune isolating barriers and indirect vascularization or 2) direct vascularization with local or systemic delivery of immune modulatory molecules. Supported by experimental data, here a broadly applicable predictive computational model capable of recapitulating both encapsulation strategies is developed. The model is employed to comparatively study the oxygen concentration at different levels of vascularization, transplanted cell density, and spatial distribution, as well as with codelivered adjuvant cells. The model is then validated to be predictive of experimental results of oxygen pressure and local and systemic drug biodistribution in a direct vascularization device with local immunosuppressant delivery. The model highlights that dense vascularization can minimize cell hypoxia while allowing for high cell loading density. In contrast, lower levels of vascularization allow for better drug localization reducing systemic dissemination. Overall, it is shown that this model can serve as a valuable tool for the development and optimization of platform technologies for cell encapsulation.

Lean-Electrolyte Lithium-Sulfur Cells with a Core-Shell Cathode Configuration with High Active-Material Loading and Energy Density

Introduction The growing demand for rechargeable batteries with increasingly high energy density and low-cost active material has inspired the research of low-cost cathodes with higher specific capacities than those based on intercalation lithium-ion cathodes. Among these novel energy storage technologies, the lithium-sulfur electrochemical cell is the most promising because of the high energy density, low cost, wide availability, and low environmental impact of the sulfur cathode. However, the high-capacity sulfur cathode forms insulating solid sulfur and lithium sulfide in the fully charged and discharged states. The resulting high cathode resistance limits electrochemical utilization and reversibility, and the resulting low redox kinetics leads to the poor rate performance of sulfur cathodes. Moreover, these solid-state active materials are converted to liquid-state polysulfides during intermediate charging and discharging. The liquid-state polysulfides readily dissolve in the lithium-sulfur battery electrolyte, resulting in irreversible polysulfide loss and poor discharge-charge efficiency of the cell. The inefficient and unstable cell electrochemistry of sulfur can be mitigated by designing appropriate configurations of cathode materials. However, the modification of cathode materials often encounters the inability to accommodate a sufficient amount of sulfur in the cathode under lean electrolyte conditions while maintaining electrochemical stability. Results and Discussion In this presentation, we present the design of a core-shell architecture for the entire cathode, which features a conductive carbon shell having a fabric-like tubular structure to accommodate an active material core and provide fast charge transfer to the active material. In addition to the novel cathode configuration, we present a summary of a number of active material cores, including a pure sulfur core and a pure lithium sulfide core as solid-state active material cores, and a polysulfide catholyte core as a liquid-state active material (Figure 1) [1-3]. With these three different core-shell cathodes, we will comprehensively report the material design with high electrochemical utilization and efficiency, and the designed cell configuration stabilizes the reversible lithium-sulfur electrochemistry. Most importantly, we propose the sulfur core to demonstrate the high-loading sulfur cathode with the highest sulfur loading and content, and the sulfide and polysulfide cores to demonstrate the lean-electrolyte cells with low electrolyte to active material ratios. Specifically, we design a series of lithium-sulfur battery cathodes with a unique cathode material and configuration. In terms of the cathode material, a high-loading sulfur cathode prepared with pure sulfur powder, a high-concentration polysulfide prepared as the catholyte, and a sulfide cathode prepared in an ether-based solvent are reported. The sulfur, polysulfide, and sulfide serve as a high-loading active materials. The conductive carbon shell encapsulates the active material during cycling and resting. The integrated design of the cathode material and configuration enables the core-shell cathodes to achieve high sulfur loadings ranging from of 4 to 30 mg cm−2 and high sulfur contents in the range of 60-70 wt%. The high-loading core-shell cathodes excellent electrochemical utilization of the large amount of active material, showing high peak charge-storage capacity of 600-800 mA∙h g−1 at C/10 rate, long cycle life of 100-200 cycles, and high rate performance of C/10-C/2 rates with long-term cyclability and high capacity retention of 70% after 200 cycles. Moreover, by using polysulfide and sulfide cores, we demonstrate a lean electrolyte cell with low electrolyte/sulfur ratios of 6-3 μL mg-1. Accordingly, the designed core-shell cathodes achieve a high areal capacity of about 10 mA∙h cm-2, high gravimetric capacities of ~500 mA∙h g-1, and an energy density of about 20 mW∙h cm-2. Conclusion In summary, we report in the presentation a summary of our high-loading core-shell sulfur cathodes and the design of their application in the development of the lean-electrolyte lithium-sulfur cells. Our core-shell cathodes exhibit excellent electrochemical utilization and retention of active material in both solid and liquid state, which shows the long cycle life and long shelf life of the high energy density lithium-sulfur cell. Figure 1. Illustration of a lithium-sulfur cell with the core-shell cathode equipped with sulfur, polysulfide, and sulfide cores. References -C. Wu, S.-H. Chung, J. Mater. Chem. A 2023, 10.1039/D3TA00210A.-H. Chung, A. Manthiram, Adv. Energy Mater. 2017, 7, 1700537.-H. Chung, A. Manthiram, Energy Environ. Sci. 2016, 9, 3188. Figure 1

An energy storage planning method for improving the security of receiving-end system considering the selection of power conversion systems

China's power demand in high load density areas is satisfied by a centralized feed of several large-capacity HVDC links, forming a typical receiving-end system, which is facing problems such as shortage of dynamic reactive power and increased risk of commutation failure. Electrochemical energy storage (ES) has characteristics such as strong dynamic active and reactive power regulation ability, rapid response and flexible control mode, making it a high-quality resource in improving the security of the receiving-end system. Therefore, it is necessary to carry out research on the methods of planning of ES in receiving-end systems. This paper mainly analyzes the role of ES in providing dynamic reactive power support. According to the different control modes of power conversion system (PCS), the ES is divided into grid-following (GFL) and grid-forming (GFM), and multi-infeed short circuit ratio (MISCR) considering both is constructed. The MISCR is taken as an objective function of the ES planning model. At the same time, the method of “accompanying network + model reconstruction” is proposed to realize the linearization calculation of MISCR. In order to compensate for the economic cost of ES investment, its energy storage function should also be used to participate in peak shaving during normal operation. Therefore, an ES planning model considering PCS selection is established, which including ES planning layer, system operation layer and accompanying network layer. Finally, the effectiveness of the proposed planning method is verified by a modified IEEE-39 system.

Clarifying the limiting factor of material utilization in thick electrodes of lithium-ion batteries

Improving the energy density of lithium-ion batteries is a goal pursued in state-of-the-art batteries, and the use of thick electrodes with high active material loading densities is one of the most effective and direct methods. Most studies indicate that the hindrance to the practical application of thick electrodes is mainly attributed to the slow charge kinetics, resulting in very low utilization of active materials. Here, this work shows that the thermodynamic properties of the electrode material also have a significant impact on the electrode reaction behavior. When the equilibrium potential of the electrode material has a strong dependence on the state of charge, it promotes the uniform reaction of the electrode active material. By simulating the full battery under low and high load conditions, the reaction behavior of the thin electrodes is dominated by the equilibrium potential curve. However, the reaction behavior of thick electrodes is regulated by both kinetics and thermodynamics and depends on the strength of the relationship between these two properties. Meanwhile, the graphite anode limits the release of the full battery capacity to a greater extent. This work points out a new direction for the practical development and application of thick electrodes.

Inclusion/energy transfer/release of L-ascorbate in the interlayer gallery of layered yttrium hydroxide

L-ascorbate (AS, Vitamin C) was intercalated into the interlayer gallery of layered yttrium hydroxide (LYH), a representative member of the layered rare earth hydroxide series (LRHs), through an ion-exchange reaction in an aqueous solution of sodium ascorbate. Based on the expansion of the interlayer space of the resulting AS-LYH hybrid, it is suggested that AS anions vertically oriented to hydroxide layers would be arranged to form a partially interdigitated bilayer in the interlayer space of LYH with a high loading capacity and density of AS. This arrangement is different from the antiparallel monolayer configuration of AS anions that are horizontally or vertically oriented to the layer of classical layered double hydroxides (LDHs). The durability of AS against light and oxidation was sufficiently enhanced in the interlayer gallery of LYH so that no degradation occurred after exposure to simulated sunlight or heating at 60 °C for a long time. Practically no release of AS from AS-LYH was observed in a saline solution and simulated sea water, whereas a sustained release of AS occurred selectively in a phosphate buffer solution, with a release process best described by the first-order model. When LYH was doped with Tb3+ activator to give it photoluminescence ability, the UV light energy absorbed for the π → π* transition of AS was efficiently transferred to Tb3+, leading to strong green emission attributed to its 5D4 → 7F5 transition.

High-density Au nanoshells assembled onto Fe3O4 nanoclusters for integrated enrichment and photothermal/colorimetric dual-mode detection of SARS-CoV-2 nucleocapsid protein

Traditional lateral flow immunoassays (LFIA) suffer from insufficient sensitivity, difficulty for quantitation, and susceptibility to complex substrates, limiting their practical application. Herein, we developed a polyethylenimine (PEI)-mediated approach for assembling high-density Au nanoshells onto Fe3O4 nanoclusters (MagAushell) as LFIA labels for integrated enrichment and photothermal/colorimetric dual-mode detection of SARS-CoV-2 nucleocapsid protein (N protein). PEI layer served not only as “binders” to Fe3O4 nanoclusters and Au nanoshells, but also “barriers” to ambient environment. Thus, MagAushell not only combined magnetic and photothermal properties, but also showed good stability. With MagAushell, N protein was first separated and enriched from complex samples, and then loaded to the strip for detection. By observation of the color stripes, qualitative detection was performed with naked eye, and by measuring the temperature change under laser irradiation, quantification was attained free of sophisticated instruments. The introduction of Fe3O4 nanoclusters facilitated target purification and enrichment before LFIA, which greatly improved the anti-interference ability and increased the detection sensitivity by 2 orders compared with those without enrichment. Moreover, the high loading density of Au nanoshells on one Fe3O4 nanocluster enhanced the photothermal signal of the nanoprobe significantly, which could further increase the detection sensitivity. The photothermal detection limit reached 43.64 pg/mL which was 1000 times lower than colloidal gold strips. Moreover, this method was successfully applied to real samples, showing great application potential in practice. We envision that this LFIA could serve not only for SARS-CoV-2 detection but also as a general test platform for other biotargets in clinical samples.

Fabrication of tungstate metal foams as efficient catalysts for dimethyl sulfoxide oxidation in a microreactor

To overcome the problems of traditional catalyst in the microreaction technology, a microreactor system with tungstate metal foam catalyst was constructed and the catalytic efficiency were investigated by dimethyl sulfoxide (DMSO) oxidation reaction as a probe reaction. Three tungstate metal (CuWO4, NiWO4, FeWO4) foams were fabricated, and inherited the porous structure from the metal foam and had a high loading density of tungstate metal crystal particles. In the lab-built flat-plate microreactor, the effects of reaction temperature, residence time, molar ratio and pH on the yield of dimethyl sulfone (MSM) were investigated, and the tungstate metal foams showed prefect catalytic activity. Compared with NiWO4 foam and FeWO4 foam, the larger specific surface area and higher porosity endow CuWO4 with a better catalytic performance. When the reaction temperature was 80 °C, the residence time was 40 min, the molar ratio was 1:1 and the pH value of the reaction system was 3, the yield of MSM reached 82.1%. Furthermore, the NiWO4 foam catalyst system showed a better performance compared with other two catalyst system. This work indicates the potential opportunity of the construction of various metal foam catalysts in the versatile continuous microreaction technology.

Anti-Shedding Nickel-Protection-Layer Boosting an Ultrahigh Loading Carbon Fiber@Co-NiSx Electrode to Deliver Superior Areal/Volumetric/Gravimetric Capacitance.

Challenges remain to show good capacitive performance while achieving high loadings of active materials for supercapacitors. Trying to realize this version, a nickel-protecting carbon fiber paper@Co-doped NiSx (Ni-CP@Co-NiSx) electrode with high specific gravimetric, areal, and volumetric capacitance is reported in this work. This free-standing electrode is prepared by an electroplating-hydrothermal-electroplating (EHE) three-step method to achieve a high loading of almost 26.7 mg cm-2. The cobalt-doping and nickel-protection strategies effectively decrease the impedance and inhibit the active material dropping from the electrode resulting from the expansion stress, which endows the Ni-CP@Co-NiSx electrode with a high rate and good cycling performance, especially with an ultrahigh specific areal/volumetric/gravimetric capacitance of 53.3 F cm-2/2807 F cm-3/1997 F g-1 at 5 mA cm-2, respectively. Employing activated carbon functionalized with riboflavin (AC/VB2) as a negative electrode, the asymmetric supercapacitor device delivers a very high energy density of up to 60.4 W h kg-1. This work demonstrates that electrodes with a high loading density and excellent performance can be obtained by the combination of the EHE method to adjust the internal conductivity and external structural stability.

Tunable Conformal Electrodeposition of Ultra-Thin Polymeric Films for Electrolyte Interphases

Functional coatings and interphases influence the stability and performance parameters of electrodes in various applications. Polymer thin films offer a wide range of molecular structures and compositions for tunable functionalities that can be custom designed to the needs of an application. In solid-state energy storage devices in particular, electrolyte-type polymeric interfaces between battery components and materials with disparate functions, such as the active electrode material and solid electrolyte could overcome some of these incompatibility detriments and the increase in contact resistance over long-term operation. In high-performance micro scale power sources, 3D thin-film all-solid-state batteries show great potential as they take advantage of both short ion diffusion distances for high-rate capability with low heat generation, as well as the third dimension for high material loading and energy density. Therefore, conformal deposition methods for ultra-thin polymeric electrolyte interphases on the interior surface of electrodes with mesoscale 3D architectures and complex porosity are in demand. Here, we report a molecular design concept of dual-functional molecules that contain electrochemically active end groups for self-limiting electropolymerization, and a core molecular motif that determines the thin film functionality. The electrodeposition of this monomer represents a non-line-of-sight coating method for polymer thin films with independently tailorable functionalities and tunable properties on conductive substrates with arbitrary shape. We exemplify this method using monomers with poly(ethylene glycol) (PEG) as the core motif for lithium-ion transport and phenol as electrochemically active end groups. We studied the electrodeposition of the monomers, poly(ethylene glycol) diphenol (PEGDP), and demonstrate their self-limiting film formation mechanism (Figure 1a) which originates from the insulating nature of resulting poly(PEGDP) film that confines the charge transfer reaction. We present an exhaustive exploration of their material-processing-structure-property relationships that reveals the multi-scale control over the ultrathin-film properties. For example, the uniform film thickness is tunable from 10 to 100s of nanometer through electrodeposition conditions and molecular design, while their molecular permeability and electronic resistance can be tailored from pervious to fully blocking. We show that the electrodeposited functional interphases fully coat complex 3D electrode architectures (Figure 1b top: uncoated carbon electrode, bottom: film coated carbon electrode) with retention of their functionality in a battery. This work demonstrates that rational molecular design enables the conformal electrodeposition of ultrathin functional coatings with solid polymer electrolyte properties on 3D structured electrodes that will enable designer interphases in various solid-state battery architectures and chemistries. Figure 1

Freezing-directed construction of enzyme/nano interfaces: Reagentless conjugation, superior activity, and better stability

Immobilizing enzyme to nano interfaces has demonstrated to be a favorable strategy for prompting the industrialized application of enzyme. Despite tremendous endeavor has been devoted to using gold nanoparticles (AuNPs) as conjugation matrix due to its fascinating physico-chemical properties, maintaining enzymatic activity while circumventing cumbersome modification remains a formidable challenge. Herein, the freezing-directed conjugation of enzyme/nano interfaces was constructed without extra reagent. As the proof of concept, glucose oxidase (GOx) was chosen as model enzyme. The one-pot conjugation process can be facilely completed at −20 °C under aqueous solution. Moreover, with the loading of GOx on AuNP at freezing, the enzyme exhibited superior catalytic activity and stability upon thermal and pH perturbation. The mechanism of boosted activity was then discussed in detail. It was found that higher loading density under freezing condition and more enzyme tending to bind AuNPs via Au-S bond were the main factors for the superior activity. More importantly, this methodology was universal and can also be applied to other enzyme which contains natural cysteine, such as horseradish peroxidase (HRP) and papain. This facile conjugation strategy accompanied by remarkable bioactivity expand the possibilities for enzymatic biosensing, microdevice and even drug delivery.

Constructing Pure Si Anodes for Advanced Lithium Batteries.

ConspectusWith the escalating demands of portable electronics, electric vehicles, and grid-scale energy storage systems, the development of next-generation rechargeable batteries, which boasts high energy density, cost effectiveness, and environmental sustainability, becomes imperative. Accelerating these advancements could substantially mitigate detrimental carbon emissions. The pursuit of main objectives has kindled interest in pure silicon as a high-capacity electroactive material, capable of further enhancing the gravimetric and volumetric energy densities compared with traditional graphite counterparts. Despite such promising attributes, pure silicon materials face significant hurdles, primarily due to their drastic volumetric changes during the lithiation/delithiation processes. Volume changes give rise to severe side effects, such as fracturing, pulverization, and delamination, triggering rapid capacity decay. Therefore, mitigating silicon particle fracture remains a primary challenge. Importantly, nanoscale silicon (below 150 nm in size) has shown resilience to stresses induced by repeated volume changes, thereby highlighting its potential as an anode-active material. However, the volume expansion stress not only affects the internal structure of the particle but also disrupts the solid-electrolyte interphase (SEI) layer, formed spontaneously on the outer surface of silicon, causing adverse side reactions. Therefore, despite silicon nanoparticles offering new opportunities, overcoming the associated issues is of paramount importance.Thus, this Account aims to spotlight the significant strides made in the development of pure silicon anodes with particular attention to feature size. From the emergence of nanoscale silicon, the following nanotechnology played a crucial role in growing the particle through nano/microstructuring. Similarly, bulk silicon microparticles gradually surfaced with the post-engineering methods owing to their practical advantages. We briefly discuss the special characteristics of representative examples from bulk silicon engineering and nano/microstructuring, all aimed at overcoming intrinsic challenges, such as limiting large volume changes and stabilizing SEI formation during electrochemical cycling. Subsequently, we outline guidelines for advancing pure silicon anodes to incorporate high mass loading and high energy density. Importantly, these advancements require superior material design and the incorporation of exceptional battery components to ensure compatibility and yield synergistic effects. By broadening the cooperative strategies at the cell and system levels, we anticipate that this Account will provide an insightful analysis of pure silicon anodes and catalyze their practical applications in real battery systems.

Design and construction of low resistance copper doped polyaniline electrode with ultrahigh loading density for high performance supercapacitor applications

Polyaniline is a promising material for the development of high performance flexible supercapacitor devices. However, the loose structure of polyaniline materials and the high intermolecular transport impedance between molecular chains remain significant technical barriers, particularly at high loading density. In this study, we developed a copper ion doped polyaniline electrode (Cu-PANI@CC) on carbon cloth using a simple one-step in-situ electrochemical deposition method. The structure and electrochemical properties of this electrode were investigated via different testing techniques. Benefiting from the catalysis and regulation of copper ions between PANI molecular chains, the electrode demonstrated a relatively low internal resistance at high loading densities (> 10 mg cm−2). Moreover, this electrode exhibited specific capacitance of 3.49 F cm−2 at 5 mA cm−2 and capacitance retention of 83.31% at 50 mA cm−2. Two Cu-PANI@CC electrodes were used to fabricate a symmetrical capacitor, which exhibited remarkable cycling stability and wide operating temperature range. The excellent electrochemical performance of the Cu-PANI@CC electrode highlights the potential for use in high-performance supercapacitor devices.