A Cellulose Reinforced Multifunctional Binder for High-Performance Silicon Anodes.

Silicon (Si) has garnered significant interest as a potential anode material for next-generation lithium-ion batteries due to its high theoretical capacity. However, Si anodes suffer from substantial volume expansion during the charge and discharge processes, which severely undermines their cycling stability. To address this issue, developing novel binders has become an effective strategy to suppress the volume expansion of Si anodes. In this study, a multifunctional polymer binder (DCCS) was designed by the cross-linking of dialdehyde cellulose nanocrystal (DACNC) and carboxymethyl chitosan (CMCS), which forms a 3D network structure via Schiff-base bonds. The DCCS binder with abundant chemical and hydroxyl bonds shows strong adhesion between Si nanoparticles and current collectors, thus enhancing the mechanical properties of the electrode. Furthermore, the DACNC also served as the protecting buffer layer to release the inner stress and stabilize the solid electrolyte interface (SEI). At 4 A g-1, the resulting Si@25%DCCS electrode demonstrated a capacity of 1637 mAh g-1 after 500 cycles, with an average capacity fading rate of 0.07% per cycle. Therefore, this multifunctional binder is considered a promising binder for high-performance Si anodes.

Double-edged role of interlayer water on Li+ extraction from ultrahigh Mg2+/Li+ ratio brines using Li/Al-LDHs.

Lithium-aluminum layered double hydroxides (Li/Al-LDHs) are the only industrial adsorbents for Li+ extraction from Mg2+/Li+ ratio brines dependent on the special neutral desorption without dissolution damage. In this work, Li/Al-LDHs with different interlayer water contents were designed for the investigation of correlation between interlayer water and Li+ adsorption performances in high Mg2+/Li+ ratio brines. On the one hand, the Li+ adsorption capacity of Li/Al-LDHs in the Qarham Salt Lake old brine with a Mg2+/Li+ ratio exceeding 300 presented a positive correlative relation with the interlayer water content, rising from 1.05 mg/g to 7.89 mg/g as the interlayer water content increased from 5.52% to 18.18%. On the other hand, the interlayer water content would not affect the structure stability of Li/Al-LDHs, while the interlayer spacing was lessened with less interlayer water resulting in an uptrend to the adsorption selectivity on account of the depressed confinement effect. The density functional theory (DFT) calculation further indicated that LiCl was easier to enter the structure of Li/Al-LDHs with more interlayer water in view of the greater interaction energy.

Flow effects on the surface properties of surfactant foam films.

The surface electrostatic properties of liquid foam, involving the electrokinetic (EK) phenomena in the liquid-gas interface, have significant effects on the stability of the foam. Here, we established a theoretical model for ion transport in liquid films by combining the liquid flow and surface reaction. We found that the surface electrostatic properties of liquid foams were influenced unexpectedly by the pressure-induced flow. The liquid flow will induce the potential and concentration differences in the flow direction. When the pressure drop increases to a certain high value, the induced potential and salt concentration difference increases, leading to the change of the surface electrostatic properties such as zeta potential and the surface charge density. This change shows that the surface electrostatic properties of foam films depend on the coupling of various factors including ion distribution and pressure drop, which deepens our understanding of the electrostatic properties of the foam films.

Understanding surface charge regulation in silica nanopores.

Nanoporous silica is used in a wide variety of applications, ranging from bioanalytical tools and materials for energy storage and conversion as well as separation devices. The surface charge density of nanopores is not easily measured by experiment yet plays a vital role in the performance and functioning of silica nanopores. Herein, we report a theoretical model to describe charge regulation in silica nanopores by combining the surface-reaction model and the classical density functional theory (CDFT). The theoretical predictions provide quantitative insights into the effects of pH, electrolyte concentration, and pore size on the surface charge density and electric double layer structure. With a fixed pore size, the surface charge density increases with both pH and the bulk salt concentration similar to that for an open surface. At fixed pH and salt concentration, the surface charge density rises with the pore size until it reaches the bulk asymptotic value when the surface interactions become negligible. At high pH, the surface charge density is mainly determined by the ratio of the Debye screening length to the pore size (λD/D).

Non-Negligible Roles of Pore Size Distribution on Electroosmotic Flow in Nanoporous Materials.

Electroosmotic flow in nanoporous materials is of fundamental importance for the design and development of filtration membranes and electrochemical devices such as supercapacitors and batteries. Recent experiments suggest that ion transport in a porous network is substantially different from that in individual nanochannels due to the pore size distribution and pore connectivity. Herein, we report a theoretical framework for ion transport in nanoporous materials by combing the classical density functional theory to describe the electrical double layer (EDL) structure, the Navier-Stokes equation for the fluid flow, and the effective medium approximation to bridge the gap between individual nanopores and the network connectivity. We find that ion conductivity in nanoporous materials is extremely sensitive to the pore size distribution when the average size of micropores is comparable to the EDL thickness. The theoretical predictions provide an explanation of the giant gap between the conductivity of a single pore and that of a porous network and highlight the mechanism of ion transport through nanoporous materials important for numerous practical applications.

Ionic Liquid-Polypyrrole-Gold Composites as Enhanced Enzyme Immobilization Platforms for Hydrogen Peroxide Sensing.

In this work, three different aqueous solutions containing imidazole-based ILs with different alkyl chain lengths ([Cnmim]Br, n = 2, 6, 12) were adopted as the medium for the synthesis of ionic liquid-polypyrrole (IL-PPy) composites. Herein, the ILs undertook the roles of the pyrrole solvent, the media for emulsion polymerization of PPy and PPy dopants, respectively. The electrochemical performances of the three IL-PPy composites on a glassy carbon electrode (GCE) were investigated by electrochemical experiments, which indicated that [C12mim]Br-PPy (C12-PPy) composites displayed better electrochemical performance due to their larger surface area and firmer immobilization on the GCE. Further, C12-PPy/GCE were decorated with Au microparticles by electrodeposition that can not only increase the conductivity, but also immobilize sufficient biomolecules on the electrode. Then, the obtained C12-PPy-Au/GCE with outstanding electrochemical performance was employed as a horseradish peroxidase (HRP) immobilization platform to fabricate a novel C12-PPy-Au-HRP/GCE biosensor for H2O2 detection. The results showed that the prepared C12-PPy-Au-HRP/GCE biosensor exhibited high sensitivity, fast response, and a wide detection range as well as low detection limit towards H2O2. This work not only provides an outstanding biomolecule immobilization matrix for the fabrication of highly sensitive biosensors, but also advances the understanding of the roles of ILs in improving the electrochemical performance of biosensors.

Predicting the capacitance of carbon-based electric double layer capacitors by machine learning.

Machine learning (ML) methods were applied to predict the capacitance of carbon-based supercapacitors. Hundreds of published experimental datasets are collected for training ML models to identify the relative importance of seven electrode features. This present method could be used to predict and screen better carbon electrode materials.

Tough Gel Electrolyte Using Double Polymer Network Design for the Safe, Stable Cycling of Lithium Metal Anode.

The growth of lithium dendrites and low coulombic efficiency restrict the development of Li metal anodes. Polymer electrolytes are expected to be promising candidates to solve the issue, but ways to obtain a polymer electrolyte that integrates high ionic conductivity and high mechanical toughness is still challenging. By introducing a double polymer network into the electrolyte design to reshape it, a tough polymer electrolyte was developed with high conductivity, and stable operation of lithium metal anodes was further realized. The double network (DNW) gel electrolyte has high modulus of 44.3 MPa and high fracture energy of 69.5 kJ m-2 . The conductivity of DNW gel is 0.81 mS cm-1 at 30 °C. By using this gel electrolyte design, the lithium metal electrode could be cycled more than 400 times with a coulombic efficiency (CE) as high as 96.3 % with carbonate-based electrolytes.

Nanocrystalline celluloses-assisted preparation of hierarchical carbon monoliths for hexavalent chromium removal.

Hierarchical porous carbon monoliths with a 3D framework were synthesized through a facile sol-gel process using resorcinol-melamine-formaldehyde (RMF) as carbon precursors, and nanocrystalline celluloses (NCCs) as the structural inducing agent, followed by ambient pressure drying and carbonization. Polymerization of the RMF resin occurs around the nanorod-like NCCs dispersed homogeneously in water, which is quite beneficial for the formation of an interconnected network and supports the rigid macroporous structure. A hierarchical porous carbon monolith with modest micropores and well-developed macropores was prepared after CO2 activation at 950°C. The microporous structure was generated from the network of RMF polymer chains, while the macroporous structure was formed from the interconnection of polymer networks induced by NCCs. The obtained carbon monolith has a large specific surface area of 1808m2g-1 and shows a high adsorption capacity of 463mgg-1 for toxic Cr(VI) ions. Moreover, the activated carbon monolith exhibits a high selectivity for Cr(VI) in the coexistence of several other metal ions. These outstanding advantages of carbon monoliths, including their micro/macroporous structures, rich functional groups, low cost and easy synthesis, endow them with potential for use in a wide range of applications.

Colloidal Synthesis of Silicon-Carbon Composite Material for Lithium-Ion Batteries.

We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface-functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil-in-water emulsions, from which yolk-shell and dual-shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li-ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li-ion anodes composed of 46 wt % of dual-shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm-2 achieve an overall specific capacity higher than 600 mAh g-1 , which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si-C composites for Li-ion batteries.

Facile preparation and ultra-microporous structure of melamine-resorcinol-formaldehyde polymeric microspheres.

A facile hydrothermal method was developed to synthesize nitrogen-rich phenolic microspheres with a tunable ultra-microporous structure for CO(2) adsorption. The results highlighted that chemical composition and ultramicroporous size, much more than surface area, dictated the CO(2) uptake in a microporous organic polymer.