Synthesis of one-dimensional graphene-encapsulated TiO2 nanofibers with enhanced lithium storage capacity for lithium-ion batteries

Journal of Solid State Electrochemistry - The one-dimensional graphene/TiO2 composite nanofibers with the unique microstructures have been successfully synthesized via an efficient method and...     

Polythiophene-coated nano-silicon composite anodes with enhanced performance for lithium-ion batteries

Herein, a new polythiophene-coated silicon composite anode material was prepared by in situ chemical oxidation polymerization method. The structure of this material was characterized by infrared spectroscopy, which proved that the oxidative polymerization of thiophene occurred mainly in α position. The polythiophene can provide the better electric contact between silicon particles. Therefore, the as-prepared Si/polythiophene composite electrodes achieve better cycling performance than the bare Si anode. The specific capacity of the composite electrode retains 478 mA h g^?1 after 50 cycles.     

A strontium-doped Li2FeSiO4/C cathode with enhanced performance for the lithium-ion battery

Journal of Solid State Electrochemistry - Strontium-doped Li2FeSiO4/C is prepared by using the sol-gel method with soluble Li, Fe, Si, and Sr sources. X-ray diffraction, scanning electron...     

Rutile-TiO2 nanocoating for a high-rate Li4Ti5O12 anode of a lithium-ion battery

Well-defined Li(4)Ti(5)O(12) nanosheets terminated with rutile-TiO(2) at the edges were synthesized by a facile solution-based method and revealed directly at atomic resolution by an advanced spherical aberration imaging technique. The rutile-TiO(2) terminated Li(4)Ti(5)O(12) nanosheets show much improved rate capability and specific capacity compared with pure Li(4)Ti(5)O(12) nanosheets when used as anode materials for lithium ion batteries. The results here give clear evidence of the utility of rutile-TiO(2) as a carbon-free coating layer to improve the kinetics of Li(4)Ti(5)O(12) toward fast lithium insertion/extraction. The carbon-free nanocoating of rutile-TiO(2) is highly effective in improving the electrochemical properties of Li(4)Ti(5)O(12), promising advanced batteries with high volumetric energy density, high surface stability, and long cycle life compared with the commonly used carbon nanocoating in electrode materials.     

Deep learning enhanced lithium-ion battery nonlinear fading prognosis

With the assistance of artificial intelligence,advanced health prognosis technique plays a critical role in the lithium-ion(Li-ion) batteries management system.However,conventional data-driven early aging prediction exhibited dramatic drawbacks,i.e.,volatile capacity nonlinear fading trajectories create obstacles to the accurate multistep ahead prediction due to the complex working conditions of batteries.Herein,a novel deep learning model is proposed to achieve a universal and accurate Li-ion b...     

Surface enhanced optical spectroscopies for bioanalysis

Surface enhancement can provide improved detection sensitivity in a range of optical spectroscopies. When applied to bioanalysis these enhanced techniques allow for the detection of disease biomarkers at lower levels, which has a clear patient benefit. However, to achieve widespread clinical use of surface enhanced techniques there remain several "grand challenges". In this review we consider the substrates employed to achieve enhancement before reviewing each enhanced optical technique in detail; surface plasmon resonance, localised surface plasmon resonance, surface enhanced fluorescence, surface enhanced infrared absorption spectroscopy and surface enhanced (resonance) Raman spectroscopy. Finally we set out the "grand challenges" currently facing the field.     

Synthesis of Carbon/Sulfur Nanolaminates by Electrochemical Extraction of Titanium from Ti2SC

Herein we electrochemically and selectively extract Ti from the MAX phase Ti₂SC to form carbon/sulfur (C/S) nanolaminates at room temperature. The products are composed of multi‐layers of C/S flakes, with predominantly amorphous and some graphene‐like structures. Covalent bonding between C and S is observed in the nanolaminates, which render the latter promising candidates as electrode materials for Li‐S batteries. We also show that it is possible to extract Ti from other MAX phases, such as Ti₃AlC₂ , Ti₃SnC₂ , and Ti₂GeC, suggesting that electrochemical etching can be a powerful method to selectively extract the “M” elements from the MAX phases, to produce “AX” layered structures, that cannot be made otherwise. The latter hold promise for a variety of applications, such as energy storage, catalysis, etc.     

Surface enhanced spectroscopy

We review the physical processes occuring when solid surfaces are used to modify, in a substantial way, the spectroscopic properties of molecules located nearby. This is achieved by enhancement of the local laser field, increase in molecular emission, and decrease in excited state lifetime. We survey the use of flat surfaces, gratings, attenuated total reflection prisms, surfaces with small and large random roughness, isolated spheres and ellipsoids, and interacting solid surfaces. The spectroscopic techniques surveyed are surface enhanced Raman, fluorescence, resonant Raman, and absorption. The possibility of enhancing photochemical processes is also discussed. We have made an effort to present all these topics from an unifying point of view and to survey the experiments relevant to the concepts presented. The level of presentation is aimed at a nonexpert or an experimentalist without extensive theoretical skills.     

Electric-controlled pressure relief valve for enhanced safety in liquid-cooled lithium-ion battery packs

The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above IP65,which can trap flammable and explosive gases from battery thermal runaway and cause explosions.This poses serious safety risks and challenges for LCBESS.In this study,we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure r...     

Surface enhanced Raman scattering for multiplexed detection

The multiplexed detection of biological analytes from complex mixtures is of crucial importance for the future of intelligent management and detection of disease. This review focuses on recent advances in the use of surface enhanced Raman scattering (SERS) spectroscopy as an analytical technique that can deliver multiplexed detection for a variety of biological target in increasingly complex media. The use of SERS has developed from the multipelxed detection of custom dye molecules to biomolecules such as DNA and proteins. Recent work has also shown the capability of SERS multiplexing for in vivo as well as in vitro applications.     

Boehmite-coated microporous membrane for enhanced electrochemical performance and dimensional stability of lithium-ion batteries

A heat-resistant boehmite-coated polypropylene (PP) membrane has been successfully fabricated and its potential application as a promising separator in the lithium-ion battery was explored. The boehmite powders with average sizes of 0.78, 1.03, and 1.72 μm, respectively, were used to fabricate the coated membrane. It was demonstrated that the coated membrane prepared by boehmite with a 0.78-μm size showed superior heat tolerance and proper air permeability. As compared to the commercialized PP membrane, such coated membrane presented improved electrolyte uptake, better interface stability, and enhanced ionic conductivity. In addition, the lithium iron phosphate (LiFePO₄)/Li cell using this composite membrane exhibited better rate capability and cycling retention than that using PP membrane owing to its facile ion transport and excellent interfacial compatibility. The coating layer showed an advantage on solid electrolyte interface film formation and greatly reduced charge transfer resistance. All these fascinating characteristics would boost the application of this composite membrane for high-performance lithium-ion battery.     

CuFeS2 as an anode material with an enhanced electrochemical performance for lithium-ion batteries fabricated from natural ore chalcopyrite

Journal of Solid State Electrochemistry - Considering serious pollution from the traditional chemical synthesis process, the resource-rich, clean electrode materials are greatly desired....     

Higher hydrogen uptake capacity of C2H4Ti+ than C2H4Ti: a quantum chemical study

Using density functionals theory, we show that gravimetric hydrogen uptake of C₂H₄Ti complex and its cation, C₂H₄Ti⁺, differ by about 2 wt%. Six and five hydrogen molecules are found to be adsorbed on C₂H₄Ti⁺ and C₂H₄Ti complexes thereby showing a hydrogen-uptake capacity of 13.74 and 11.72 wt%, respectively. All hydrogen molecules are adsorbed in molecular form on C₂H₄Ti⁺ ion with an increase in metal bond strength, whereas in some cases, the hydrogen molecules are found to be dissociated on C₂H₄Ti neutral complex. The uptake capacity of neutral C₂H₄Ti complex shown in this work is in excellent agreement with that reported experimentally, Phillips and Shivaram (Phys Rev Lett 100:105505, 2008). The H₂ adsorption energy and its dependence on exchange and correlation functions in density functionals method were illustrated. Even after the adsorption of maximum number of hydrogen molecules on C₂H₄Ti and C₂H₄Ti⁺ complexes, Ti and Ti⁺ remain strongly bound to C₂H₄ substrate.     

Surface modification of polyurethane for enhanced blood compatibility

Surfaces of commercial polyurethanes (PUs) were modified by poly(ethylene oxide) (PEO) grafting and/or heparin immobilization or sulfonation to investigate the effect to antithrombogenicity. The hydrophilicity of the modified PUs surface was significantly increased. All the PEO-grafted PU surfaces displayed very little platelet adhesion and activation. The coupled heparin or sulfonate at the end of PEO exhibited anticoagulant activity to extend APTT. Lowering in vitro platelet adhesion of modified PUs led to a prolongation in the ex vivo occlusion time. In particular, the sulfonated PU-PEO surface showed the most enhanced blood compatibility due to the synergistic effects of PEO and SO₃ groups.     

Nitridated mesoporous Li4Ti5O12 spheres for high-rate lithium-ion batteries anode material

Nitridated mesoporous Li₄Ti₅O₁₂ spheres were synthesized by a simple ammonia treatment of Li₄Ti₅O₁₂ derived from mesoporous TiO₂ particles and lithium acetate dihydrate via a solid state reaction in the presence of polyethylene glycol 20000. The carbonization of polyethylene glycol could effectively restrict the growth of primary particles, which was favorable for lithium ions diffusing into the nanosized TiO₂ lattice during the solid state reaction to form a pure phase Li₄Ti₅O₁₂. After a subsequent thermal nitridation treatment, a high conductive thin TiO _x N _y layer was in situ constructed on the surface of the primary nanoparticles. As a result, the nitridated mesoporous Li₄Ti₅O₁₂ structure, possessing shorter lithium-ion diffusion path and better electrical conductivity, displays significantly improved rate capability. The discharge capacity reaches 138 mAh?g^?1 at 10 C rate and 120 mAh?g^?1 at 20 C rate in the voltage range of 1–3 V.     

Synthesis of MgCo2O4-coated Li4Ti5O12 composite anodes using co-precipitation method for lithium-ion batteries

Journal of Solid State Electrochemistry - In the present work, we report synthesis of MgCo2O4 (MCO)/Li4Ti5O12 (LTO) composites for Li-ion battery anodes by a co-precipitation method. The objective...     

VO2 nano-sheet negative electrodes for lithium-ion batteries

Vanadium dioxide (VO₂) nano-sheets were directly synthesized via a continuous hydrothermal process and were investigated as electrodes in a wide potential range of 0.05–3 V vs. Li/Li⁺. The nano-sheets showed excellent capacity retention, with a specific capacity of 350 mAh g^− 1 at an applied current of 0.1 A g^− 1 and 95 mAh g^− 1 at 10 A g^− 1. Further electrochemical testing suggested that a significant proportion of the charge storage in the cells was due to pseudocapacitive processes.     

Electrodeposition of mesoporous V2O5 with enhanced lithium-ion intercalation property

Mesoporous vanadium oxide (V₂O₅) thin films were deposited electrochemically onto indium tin oxide-coated glass substrates from an aqueous solution of vanadyl sulfate using CTAB (hexadecyltrimethylammonium bromide) as a templating agent. For comparison, a control sample was electrodeposited without CTAB templating. Transmission electron microscopy and small angle X-ray diffraction indicated the presence of mesoporosity with a well-ordered lamellar phase in the electrodeposited films. The crystallinity of the V₂O₅ thin films was confirmed by X-ray diffraction. Cyclicvoltammetry and chronoamperometry were used to measure electrochemical properties of synthesized films. The mesoporous films prepared with CTAB templating had a much higher capacity and lithium-ion diffusion rate than the non-porous electrode prepared without CTAB templating.     

Constructing oxygen-deficient V2O3@C nanospheres for high performance potassium ion batteries

Potassium ion batteries (PIBs) have been regarded as promising alternatives to lithium ion batteries (LIBs) on account of their abundant resource and low cost in large scale energy storage applications. However, it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V₂O₃ nanoparticles encapsulated in amorphous carbon shell (O_d-V₂O₃@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K⁺ migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, O_d-V₂O₃@C electrode exhibits superior rate capability (reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and 2000 mA/g, respectively), and ultralong cycle life (127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.     

Construction of PMIA@PAN/PVDF-HFP/TiO2 coaxial fibrous separator with enhanced mechanical strength and electrolyte affinity for lithium-ion batteries

Poly(m-phthaloyl-m-phenylenediamine) (PMIA) is promising as the separator in lithium-ion batteries (LIBs) for its excellent thermostability, insulation and self-extinguishing properties. However, its low mechanical strength and poor electrolyte affinity limit its application in LIBs. In this work, a new PMIA@polyacrylonitrile-polyvinylidene fluoride hexafluoropropylene-titanium dioxide (PMIA@PAN/PVDF-HFP/TiO₂) composite fibrous separator with a coaxial core-shell structure was developed by combining coaxial electrospinning, hot pressing, and heat treatment techniques. This separator not only inherits the exceptional thermostability of PMIA, showing no evident thermal shrinkage at 220 °C, but also reveals improved mechanical strength (29.7 MPa) due to the formation of firm connections between fibers with the melted PVDF-HFP. Meanwhile, the massive polar groups in PVDF-HFP play a vital role in improving the electrolyte affinity, which renders the separator a high ionic conductivity of 1.36 × 10⁻³ S/cm. Therefore, the LIBs with PMIA@PAN/PVDF-HFP/TiO₂ separators exhibited excellent cycling and rate performance at 25 °C, and a high capacity retention rate (76.2%) at 80 °C for 200 cycles at 1 C. Besides, the lithium metal symmetric battery assembled by the separator showed a small overpotential, indicating that the separator had a role in inhibiting lithium dendrites. In short, the PMIA@PAN/PVDF-HFP/TiO₂ separator possesses a wide application prospect in the domain of LIBs.