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Poly(methyl methacrylate)-Based Gel Polymer Electrolyte for High-Performance Solid State Li-O-2 Battery with Enhanced Cycling Stability
No full textThe lithium oxygen (Li-O-2) battery is considered as one of the promising next-generation energy storage devices due to its high theoretic specific energy. However, some critical problems such as solvent evaporation, lithium dendrites, liquid electrolyte leakage, and liquid electrolyte decomposition under high voltage seriously hinder its application. To address these issues, a well-designed poly(methyl methacrylate) (PMMA) and SiO2 composite gel polymer electrolyte (PMMA/SiO2/PP@GPE) is prepared by a phase inversion method followed by a gelation process. Benefitting from this unique architecture, the PMMA/SiO2/PP@GPE exhibits high liquid electrolyte uptake ability and adequate gelation degree, which result in well-enhanced electro-chemical performances and interfacial stability. Compared with traditional polypropylene (PP) separator and liquid electrolyte systems, the electrochemical window of a solid state Li-O-2 battery was widened to 4.9 V, and the lithium-ion transference number increased to 0.54. A lithium symmetrical battery displays an enhanced cycling stability due to improved interface compatibility. As a consequence, the solid state Li-O-2 battery employing PMMA/SiO2/PP@ GPE delivers the high first charge-discharge capacity of 6.8 mAh cm(-2) and a stable cyclic performance of 116 cycles with 0.5 mAh cm(-2)
Designing High Entropy Structure in Thermoelectrics
No full textWith the fascinating properties observed in high entropy alloys, the idea of high entropy design has been applied to many material fields. Thermoelectric materials have some particular requirements for high entropy structure according to their transport characteristics. Here, we revealed that the high entropy structure for thermoelectrics required less lattice distortion, and the doping sites should have less influence on the Fermi surface. In the designed compound of Cu0.8Ag0.2Zn0.1Ga0.4Ge0.1In0.4Te2, the room-temperature thermal conductivity is reduced by 80% as compared to the matrix, and the maximum ZT is enhanced to 1.02. In SnTe, the solid solution of AgSbSe2 reduces the room-temperature thermal conductivity by 80%, reaching 1.3 W.m(-1).K-1. This study shows that the high entropy structure following the proposed designing rules could be an important strategy for thermoelectrics
A polyurethane integrating self-healing, anti-aging and controlled degradation for durable and eco-friendly E-skin
No full textTwo of the very important demands for the elastic matrix of electronic skin (E-skin) are durability and degradability, which ensure the stable performance in daily life and green end of the E-skin. Unfortunately, these two requirements are usually incompatible. Here, we proposed the idea of controlled degradation and synthesized a polyurethane, AL-PU-4, to solve such challenge. High crystalline hydroxy-terminated poly (1,4-butylene adipate) (HTPBA) and low crystalline polycaprolactone diol (PCL diol) were mixed and used as the degradable soft segment. The dynamic disulfide bond was chosen as the chain extender, which could simultaneously endow the polyurethane with anti-aging and self-healing properties. The AL-PU-4 didn't show significant loss in mechanical and molecular weight after 12 days of accelerated aging experiment, which equaled to 12 months of daily use, and it owned a fast room temperature self-healing speed of 1.31 mu m/min. With the steric protection of the hard segment, the degradation of ester bonds in HTPBA and PCL diol segments was seriously retarded under enzymatic and low pH conditions. Only when the pH reached 14, the 'lock' on degradation was opened. The above functionalities were also verified in an E-skin demo, which could response the external pressure quickly and show high stability in cyclic test
New thermodynamic interpretation of T-0 curves in glass forming alloys
No full textThis study presents a new thermodynamic interpretation of T-0 curves in eutectic phase diagrams. By analyzing the Gibbs energy variation of liquid-solid transition in energy-composition schematics, we illustrated the thermodynamic particularities of the T-0 curves. They are experimentally observed to be boundaries between the partitionless crystallization and amorphous areas in phase diagrams. Our interpretation basically rationalizes the capability of T-0 curves in predicting new glass forming systems and their glass forming regions. Good agreements between the thermodynamic indicator phase diagram + T-0 curves for metallic glasses and the experimental information were obtained in typical systems. (C) 2021 Elsevier B.V. All rights reserved
Impact of CO2 activation on the structure, composition, and performance of Sb/C nanohybrid lithium/sodium-ion battery anodes
No full textAntimony (Sb) has been regarded as one of the most promising anode materials for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) and attracted much attention in recent years. Alleviating the volumetric effect of Sb during charge and discharge processes is the key point to promote Sb-based anodes to practical applications. Carbon dioxide (CO2) activation is applied to improve the rate performance of the Sb/C nanohybrid anodes caused by the limited diffusion of Li/Na ions in excessive carbon components. Based on the reaction between CO2 and carbon, CO2 activation can not only reduce the excess carbon content of the Sb/C nanohybrid but also create abundant mesopores inside the carbon matrix, leading to enhanced rate performance. Additionally, CO2 activation is also a fast and facile method, which is perfectly suitable for the fabrication system we proposed. As a result, after CO2 activation, the average capacity of the Sb/C nanohybrid LIB anode is increased by about 18 times (from 9 mA h g(-1) to 160 mA h g(-1)) at a current density of 3300 mA g(-1). Moreover, the application of the CO2-activated Sb/C nanohybrid as a SIB anode is also demonstrated, showing good electrochemical performance
Structure and Properties of Regenerated Cellulose Fibers Based on Dissolution of Cellulose in a CO2 Switchable Solvent
No full textDevelopment of an effective, nontoxic, and easy-to-process novel cellulose dissolution system for the preparation of regenerated cellulose fibers is of great importance and necessity for a greener and more sustainable future, with which the traditional viscose process with serious pollution can be gradually substituted. Herein, we demonstrated the successful utilization of a CO2 switchable solvent, a novel cellulose derivative dissolution system resembling viscose but without releasing toxic gases such as CS2 and H2S, for the preparation of regenerated cellulose fibers. The corncob cellulose raw material can be readily dissolved completely after the capture of CO2 in dimethyl sulfoxide (DMSO) with 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU), resulting in cellulose spinning dope with high stability. Results showed that regenerated cellulose fibers with smoother surface morphology, a higher degree of crystallinity, and satisfactory mechanical properties were obtained under mild conditions with relatively slower double diffusion. Moreover, drawing treatment further increased the degree of crystallinity and orientation and the mechanical properties. All fibers had a dense structure, circular cross sections, no fibrillation, and high thermal stability. The regenerated cellulose fibers had degrees of crystallinity and orientation and tensile strength of 75.3%, 0.82, and 1.05 cN/dtex and 68.4%, 0.82, and 1.00 cN/dtex, respectively, in water and 30 vol % DMSO coagulation baths with a drawing ratio of 2.0 and 1.5, respectively. This work illustrated that the CO2 switchable solvent, which could be considered as green viscose, is a good candidate with great potential for the preparation of regenerated cellulose fibers with high performance and various functionalities in the future
Control of the metal-insulator transition in NdNiO3 thin films through the interplay between structural and electronic properties
No full textHeteroepitaxy offers a new type of control mechanism for the crystal structure, the electronic correlations, and thus the functional properties of transition-metal oxides. Here we combine electrical transport measurements, high-resolution scanning transmission electron microscopy (STEM), and density functional theory (DFT) to investigate the evolution of the metal-to-insulator transition (MIT) in NdNiO3 films as a function of film thickness and NdGaO3 substrate crystallographic orientation. We find that for two different substrate facets, orthorhombic (101) and (011), modifications of the NiO6 octahedral network are key for tuning the transition temperature T-MIT over a wide temperature range. A comparison of films of identical thickness reveals that growth on [101]-oriented substrates generally results in a higher T-MIT, which can be attributed to an enhanced bond disproportionation as revealed by the DFT+U calculations, and a tendency of [011]-oriented films to formation of structural defects and stabilization of nonequilibrium phases. Our results provide insights into the structure-property relationship of a correlated electron system and its evolution at microscopic length scales and give new perspectives for the epitaxial control of macroscopic phases in metal-oxide heterostructures
Public-Health-Driven Microfluidic Technologies: From Separation to Detection
No full textSeparation and detection are ubiquitous in our daily life and they are two of the most important steps toward practical biomedical diagnostics and industrial applications. A deep understanding of working principles and examples of separation and detection enables a plethora of applications from blood test and air/water quality monitoring to food safety and biosecurity; none of which are irrelevant to public health. Microfluidics can separate and detect various particles/aerosols as well as cells/viruses in a cost-effective and easy-to-operate manner. There are a number of papers reviewing microfluidic separation and detection, but to the best of our knowledge, the two topics are normally reviewed separately. In fact, these two themes are closely related with each other from the perspectives of public health: understanding separation or sorting technique will lead to the development of new detection methods, thereby providing new paths to guide the separation routes. Therefore, the purpose of this review paper is two-fold: reporting the latest developments in the application of microfluidics for separation and outlining the emerging research in microfluidic detection. The dominating microfluidics-based passive separation methods and detection methods are discussed, along with the future perspectives and challenges being discussed. Our work inspires novel development of separation and detection methods for the benefits of public health
Boosting transparent electromagnetic interference shielding by multi-cavity resonances
No full textWe propose a multi-cavity resonant architecture that is established by employing two opposing ultrathin silver-based films to forma Fabry-Perot (F-P) cavity and inserting one or two metallic mesh layers in between. Compared with the single F-P cavity, the multi-cavity architecture with one metallic mesh layer experimentally exhibits a similar to 37% improvement in the average shielding effectiveness and maintains a transmittance over 80% at 550 nm. A more significant improvement of similar to 108% in shielding effectiveness (SE) can be achieved by inserting two metallic mesh layers. The proposed multi-cavity architecture provides a strategy for removal of the hindrance to transparent electromagnetic interference shielding. (C) 2021 Optical Society of Americ
Carbon nano-onions as a nanofiller for enhancing thermal conductivity of epoxy composites
No full textCarbon nano-onions (CNOs) are a relatively new member in zero-dimensional carbon nanomaterials. Each constituent unit of CNOs is a multi-layer concentric spherical structure composed of multiple fullerene-like carbon spheres. CNOs are widely used for electronic components applications due to their large specific surface area and high electric conductivity. But a few works of CNOs on thermal conduction property in electronic device applications were studied. Therefore, we prepared the CNOs/epoxy composites by blending and casting method, and investigated the thermal conduction mechanism of CNOs in the epoxy matrix. The results show that the thermal conductivity of epoxy composite with 30 wt% CNOs loading reaches 0.59 W m(-1) K-1 due to the formation of an effective thermal network of CNOs in epoxy resin, increasing by 320% in comparison with neat epoxy. In view of excellent thermal conduction performance, CNOs may be enable used as thermal conductive filler for the thermal management of electronic components