The effects of amino groups and open metal sites of MOFs on polymer-based electrolytes for all-solid-state lithium metal batteries

Metal-organic frameworks(MOFs) are becoming more and more popular as the fillers in polymer electrolytes in recent years. In this study, a series of MOFs(NH_(2)-MIL-101(Fe), MIL-101(Fe), activated NH_(2)-MIL-101(Fe) and activated MIL-101(Fe)) were synthesized and added to PEO-based solid composite electrolytes(SCEs). Furthermore, the role of the —NH_(2) groups and open metal sites(OMSs) were both examined. Different ratios of MOFs vs polymers were also studied by the electrochemical characterizations. At last, we successfully designed a novel solid composite electrolyte containing activated NH_(2)-MIL-101(Fe),PEO, Li TFSI and PVDF for the high-performance all-solid-state lithium-metal batteries. This work might provide new insight to understand the interactions between polymers and functional groups or OMSs of MOFs better.

Practical development and challenges of garnet-structured Li_(7)La_(3)Zr_(2)O_(12) electrolytes for all-solid-state lithium-ion batteries:A review

All-solid-state Li-ion batteries(ASSLIBs)have been widely studied to achieve Li-ion batteries(LIBs)with high safety and energy density.Recent reviews and experimental papers have focused on methods that improve the ionic conductivity,stabilize the electrochemical performance,and enhance the electrolyte/electrode interfacial compatibility of several solid-state electrolytes(SSEs),including oxides,sulfides,composite and gel electrolytes,and so on.Garnet-structured Li_(7)La_(3)Zr_(2)O_(12)(LLZO)is highly regarded an SSE with excellent application potential.However,this type of electrolyte also possesses a number of disadvantages,such as low ionic conductivity,unstable cubic phase,and poor interfacial compatibility with anodes/cathodes.The benefits of LLZO have urged many researchers to explore effective solutions to overcome its inherent limitations.Herein,we review recent developments on garnet-structured LLZO and provide comprehensive insights to guide the development of garnet-structured LLZO-type electrolytes.We not only systematically and comprehensively discuss the preparation,element doping,structure,stability,and interfacial improvement of LLZOs but also provide future perspectives for these materials.This review expands the current understanding on advanced solid garnet electrolytes and provides meaningful guidance for the commercialization of ASSLIBs.

Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO_(2) fillers for high-performance all solid-state lithium metal batteries

Anion-immobilized solid composite electrolytes(SCEs)are important to restrain the propagation of lithium dendrites for all solid-state lithium metal batteries(ASSLMBs).Herein,a novel SCEs based on metal-organic frameworks(MOFs,UiO-66-NH_(2))and superacid ZrO_(2)(S-ZrO_(2))fillers are proposed,and the samples were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),thermo-gravimetric analyzer(TGA)and some other electrochemical measurements.The-NH_(2) groups of UiO-66-NH_(2) combines with F atoms of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)chains by hydrogen bonds,leading to a high electrochemical stability window of 5 V.Owing to the incorporation of UiO-66-NH_(2) and S-ZrO_(2) in PVDF-HFP polymer,the open metal sites of MOFs and acid surfaces of S-ZrO_(2) can immobilize anions by strong Lewis acid-base interaction,which enhances the effect of immobilization anions,achieving a high Li-ion transference number(t_(+))of 0.72,and acquiring a high ionic conductivity of 1.05×10^(-4) S·cm^(-1) at 60℃.The symmetrical Li/Li cells with the anion-immobilized SCEs may steadily operate for over 600 h at 0.05 mA·cm^(-2) without the shortcircuit occurring.Besides,the solid composite Li/LiFePO_(4)(LFP)cell with the anion-immobilized SCEs shows a superior discharge specific capacity of 158 mAh·g^(-1) at 0.2 C.The results illustrate that the anion-immobilized SCEs are one of the most promising choices to optimize the performances of ASSLMBs.

Optimize Multiple Peening Effects on Surface Integrity and Microhardness of Aluminum Alloy Induced by LSP

Laser shock peening is a modernized surface enhancement performed methodically to improve fatigue life, enhance the hardness of the material and make coarse grains flat under the superficial layer. In this current study, the effect of varying optimized multiple laser shock peening (LSP) is studied on the surface integrity, microhardness, and mechanical properties. The results show that the LSP-treated specimens have visible signs of valleys, wavy and varying height distribution as well as dimples. However, the presence of non-uniformity and sharp protrusions was detected from the superficiality of the as-received specimen and this was so because of the SiC abrasive material used to polish the superficial layer of the specimen before the test experiment. Prior to LSP, the surface roughness was 2 μm, however, after LSP the roughness increased to 4 μm, 6 μm and 17 μm for 1, 2, and 4 impacts, respectively. High-density dislocation can also be observed close to the grain boundary because the grain boundary prevents the migration of dislocation which could lead to dislocation walls and dislocation tangles. The increase in impacts decrease the average grain size, nevertheless, the micro-strain increased after multiple impacts. Furthermore, coarse grains after LSP were transformed into finer grains. The increase in the number of impacts increases the micro-strain likewise the full-width half maximum (FWHM). Finally, the increase in microhardness increases as the LSP impacts increase.

Experimental Investigation of Two-Phase Flow Maldistribution in Plate Heat Exchangers

After conducting a critical survey of the different categories of existing heat exchangers,the results of several experiments about the behaviour of a two-phase current in an open channel are reported.The results confirm the complexity of the problems induced in heat exchangers by flow maldistribution,especially when two-phase flows are considered in multi-channel systems.It is shown that severe misalignment of heat exchangers can lead to a loss of economic performance of more than 25%.Improper distribution of fluid flow causes longer fluid coils to form,and the liquid cochlea can eventually occupy a large space,thereby reducing heat transfer and disrupting the considered biphasic system.The use of a small diameter distribution pipe with properly spaced outlet holes seems to be a promising approach to fix many of these issues.It is found that the current distribution in the channels,in addition to the header pressure distribution,also depends on factors such as the geometry and the initial flow regime in the header.

Optimization of the Cooling System of Electric Vehicle Batteries

The most important components of electrical vehicles are the battery and the related cooling system.These subsystems play a major role in determining the overall electric vehicle performances.In this study,a novel cooling system with fluid in the battery cell is proposed,by which the energy storage system can be optimized through control of the temperature of the batteries.A sensitivity analysis is conducted considering the maximum temperature,the heat rate,the coolant temperature,and the geometry of the cavities.The numerical simulations show that the parameters for the trapezoidal compartment have an impact on the thermal performance of battery.An optimal geometry is proposed accordingly.It is concluded that for high values of Reynolds number for which the flow becomes turbulent,a decrease in the battery temperature can be obtained thereby avoiding thermal stresses.

Mechanisms and absolute quantum yield of upconversion luminescence of fluoride phosphors

Mechanisms of upconversion luminescence(UCL) of SrF_2:Er phosphors corresponding to the ~4G_(11∕2)→~4I_(15∕2),~2H_(9∕2)→~4I_(15∕2),~4F_(5∕2)→~4I_(15∕2),~4F_(7∕2)→~4I_(15∕2),~2H_(11∕2)→~4I_(15∕2),~4S_(3∕2)→~4I_(15∕2),~4F_(9∕2)→~4I_(15∕2), and ~4I_(9∕2)→~4I_(15∕2) transitions upon excitation of the ~4I_(11∕2) level of Er^(3+)ions were investigated. Energy transfer upconversion processes are responsible for the populating of the ~2H_(9∕2),~2H_(11∕2),~4S_(3∕2), and ~4F_(9∕2) levels. Cooperative process is the dominant mechanism of luminescence from ~4S_(3∕2) and ~4F_(9∕2) levels for SrF_2:Er with high concentrations of Er^(3+)ions. The UCL from ~4G_(11∕2) and ~4F_(5∕2) is explained by excited-state absorption. Cross-relaxation processes take part in the population of ~4F_(9∕2) and ~4I_(9∕2) levels. For quantifying material performance, the Er^(3+)-concentration dependence of UCL and the absolute quantum yields of SrF_2:Er were studied. The most intensive visible luminescence was obtained for SrF_2:Er(14.2%) with 0.28% maximum quantum yield.