High-performance PVDF-HFP based gel polymer electrolyte with a safe solvent in Li metal polymer battery

Poly(vinylidenefluoride-co-hexafluoropropylene)(PVDF-HFP)based gel polymer electrolytes are widely studied owing to their electrochemical stability and high dielectric constant.However,most gel polymer electrolytes show unsatisfied safety and interface compatibility due to excessive absorption of volatile and flammable liquid solvents.Herein,by using a safe solvent(N-methyl-2-pyrrolidone)with higher boiling(203℃)and flash points(95℃),we initiatively fabricate a flexible PVDF-HFP based gel polymer electrolyte.The obtained gel polymer electrolyte demonstrates a high ionic conductivity of 7.24×10^−4 S cm−1,an electrochemical window of 5.2 V,and a high lithium transference number of 0.57.As a result,the synthesized polymer electrolyte exhibits a capacity retention of 70%after 500 cycles at 0.5 C,and a discharge capacity of 86 mAh g−1 even at a high current rate of 10 C for LiFePO4 based Li metal batteries.Moreover,a stable Li plating/stripping for more than 500 h is achieved under 0.1 mAh at both room temperature and 70℃.Our results indicate that the PVDF-HFP polymer electrolyte is promising for manufacturing safe and high-performance Li metal polymer batteries.

“Polymer-in-ceramic” based poly(ε-caprolactone)/ceramic composite electrolyte for all-solid-state batteries

Inspired by the concept of "polymer-in-ceramic",a composite poly(ε-caprolactone)(PCL)/ceramic containing LiTFSI is prepared and investigated as a solid electrolyte for all-solid-state batteries.The composite with the optimum concentration of 45 wt% LiTFSI and 75 wt% Li1.5Al0.5Ge1.5(PO4)3(LAGP,NASICON-type structure) exhibits a high ionic conductivity(σi=0.17 mS cm-1) at 30℃,a transference number of 0.30,and is stable up to 5.0 V.The composite electrolyte is a flexible and self-standing membrane.Solid-state LiFePO4//Li batteries with this composite electrolyte demonstrate excellent cycling stability with high discharge capacity of 157 mA h g-1,high capacity retention of 96% and coulombic efficiency of 98.5% after 130 cycles at 30℃ and 0.1 C rate.These electrochemical properties are better than other PCL-based allsolid-lithium batteries,and validate the concept of "polymer-in-ceramic" by avoiding the drawback of lower conductivity in prior "polymer-in-ceramic" electrolyte at high concentration of the ceramic.

Research on 48 V Super Capacitor Micro Hybrid System with 12 V Power Supply Multiplexing Function

48 V lithium battery micro hybrid system is the most fuel economy vehicle which can be mass produced at present.However,with the irreversible internal resistance increase of the key component 48 V lithium battery,and the capacity continues to decline,the system performance deteriorate.Worst case could be the system not functional in the middle and later age of vehicle life cycle.This paper studies the feasibility of using 48 V super capacitor as the replacement to 48 V lithium battery,and uses a 12 V module of 48 V super capacitor as the traditional 12 V power supply,further reducing the number of components or reducing the demand for parts of 48 V micro hybrid system.This paper analyses the 48 V super capacitor micro hybrid system scheme,based on which a prototype is built,and carries out the vehicle comparative test.The results show that:(1)The performance of 48 V super capacitor micro hybrid system perform comparably with 48 V lithium battery micro hybrid system,and 12 V multiplexing function does not cause power loss of super capacitor;(2)The SOC fluctuation of super capacitor is larger than that of lithium battery,but it can satisfy all test conditions through the strategy;(3)The voltage mutation of super capacitor is smaller than that of lithium battery.It can greatly reduce the impact of voltage on vehicle electrical appliances.The 48 V super capacitor micro hybrid system with 12 V multiplexing function is of great significance.

Experimental demonstration of a flexible-grid 1×(2×3)mode-and wavelength-selective switch using silicon microring resonators and counter-tapered couplers

A flexible-grid 1×(2×3)mode-and wavelength-selective switch which comprises counter-tapered couplers and silicon microring resonators has been proposed,optimized,and demonstrated experimentally in this work.By carefully thermally tuning phase shifters and silicon microring resonators,mode and wavelength signals can be independently and flexibly conveyed to any one of the output ports,and different bandwidths can be generated as desired.The particle swarm optimization algorithm and finite difference time-domain method are employed to optimize structural parameters of the twomode(de)multiplexer and crossing waveguide.The bandwidth-tunable wavelength-selective optical router composed of12 microring resonators is studied by taking advantage of the transfer matrix method.Measurement results show that,for the fabricated module,cross talk less than-10.18 dB,an extinction ratio larger than 17.41 d B,an in-band ripple lower than0.79 dB,and a 3-dB bandwidth changing from 0.38 to 1.05 nm are obtained,as the wavelength-channel spacing is 0.40 nm.The corresponding response time is measured to be 13.64μs.

Group 2 innate lymphoid cells resolve neuroinflammation following cerebral ischaemia

Background Acute brain ischaemia elicits pronounced inflammation,which aggravates neural injury.However,the mechanisms governing the resolution of acute neuroinflammation remain poorly understood.In contrast to regulatory T and B cells,group 2 innate lymphoid cells(ILC2s)are immunoregulatory cells that can be swiftly mobilised without antigen presentation;whether and how these ILC2s participate in central nervous system inflammation following brain ischaemia is still unknown.Methods Leveraging brain tissues from patients who had an ischaemic stroke and a mouse model of focal ischaemia,we characterised the presence and cytokine release of brain-infiltrating ILC2s.The impact of ILC2s on neural injury was evaluated through antibody depletion and ILC2 adoptive transfer experiments.Using Rag2−/−γc−/−mice receiving passive transfer of IL-4−/−ILC2s,we further assessed the contribution of interleukin(IL)-4,produced by ILC2s,in ischaemic brain injury.Results We demonstrate that ILC2s accumulate in the areas surrounding the infarct in brain tissues of patients with cerebral ischaemia,as well as in mice subjected to focal cerebral ischaemia.Oligodendrocytes were a major source of IL-33,which contributed to ILC2s mobilisation.Adoptive transfer and expansion of ILC2s reduced brain infarction.Importantly,brain-infiltrating ILC2s reduced the magnitude of stroke injury severity through the production of IL-4.Conclusions Our findings revealed that brain ischaemia mobilises ILC2s to curb neuroinflammation and brain injury,expanding the current understanding of inflammatory networks following stroke.

Single-atom skeletal editing of 2H-indazoles enabled by difluorocarbene

A novel difluorocarbene promoted single-atom skeletal editing of 2H-indazoles is demonstrated herein.Ethyl bromodifluoroacetate was severed as the difluorocarbene source in the current protocol,facilitating the cleavage of the N-N bond via carbon atom insertion.This metal-free ring expansion reaction enables the late-stage diversification of indazole skeletons,assembling a diverse array of functionalized quinazolin-4(3H)-ones in decent yields with excellent functional group compatibility.