Experimental evaluation of thermolysis-driven gas emissions from LiPF6-carbonate electrolyte used in lithium-ion batteries

This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and oxygen concentrations.Carried out in a home-built autoclave filled with pure helium,the experiment reveals that as the decomposition temperature increases,more types and larger quantities of gases will be released.Specifically,the experimental results demonstrate trends of logistic growth in the volume concentration of CO2,C2H6O,C2H4,CO,and C2H4O2 with the increase of decomposition temperature.With a prolonged pyrolysis duration,while volume concentrations of certain gases,such as CO2,C2H6O,C2H5F,and CO would increase,the concentration of C2H4O2 actually decreases.Moreover,concentrations of both C2H4 and C2H5F will first decrease and reach their minimum values at 1%v/v oxygen concentration,and then they would quickly climb back at higher oxygen concentrations,while the concentrations of C2H6 and C2H3F would decrease monotonically.It is envisioned that the detailed experimental results and findings on the gas generation pattern of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes can facilitate the development of an early warning mechanism of thermal runaway based on gas sensing technology,which can be effectively applied to monitor the potential thermal failures of lithium-ion batteries with the same type of electrolyte and thus promote the thermal safety of battery packs in safety-critical applications.

CHEMISTRY OF 1,2,4—TRIAZINES XIX THE ANOMALOUS SUBSTITUTED BENZENE SULFONATION AND PROPERTIES OF NUCLEOPHILIC ATTACK ON 6-CARBON OF 3-METHYLTHIO-5-HYDROXY-1,2,4-TRIAZINE

3-Methylthio-5-hydroxy-1,2,4-triazine(1c)reacted with substituted benzenesulfonyl chloride to give 3-methylthio-5-oxy-1,2,4-triazin-6-yl pyridinium betaine(4)in anhydrous pyridine.But when NaOH/H_2O/CH_3COCH_3 or NaOH/CH_3OH were used as reactant and solvent,3-methylthio-4-substituted benzenesulfonyl-5-oxo-6-hydroxy-1,4,5,6-tetrahydro-1,2,4-triazine(6)or 1-tosyl-3-methylthio-5-oxo-6-methyloxy-1,4,5,6-tetrahydro-1,2,4-triazine(7)was obtained respectively.The above reactions show anomalous properties of nucleophilic attack on 6-carbon in 1,2,4-triazine ring.

Hydrothermal Synthesis and Crystal Structure of a New 2D Layered Cadmium(II) Coordination Polymer:[Cd(bimc)_2]_n(bimc=1H-Benzimidazole-5-carboxylate)

A new coordination polymer [Cd（bimc）2]n was obtained by the reaction of Hbimc with Cd（NO3） 2·4H2O in NaOH solution, and characterized by elemental analysis, IR and singlecrystal X-ray diffraction. The crystal belongs to orthorhombic, space group Pbcn with a = 12.533（4）, b = 15.705（5）, c = 15.200（5） A, V= 2991.8（15） A^3, Mr = 434.68, Z = 8, Dc = 1.930 g/cm^3, F（000） = 1712,μ（MoKa） = 1.492 mm^-1, the final R = 0.0410 and wR = 0.0804 for 1661 observed reflections （I 〉 2σ（I））. The Cd atom exhibits a distorted six-coordinate CdNzOa octahedral coordination geometry. The complex molecules are linked by both μ2-（η2-O, O^-）, NI and μ2-（η2-O, O^-）, N3 coordination modes of ligands to form cross-like wave （4, 4） layer structures which are further stacked through interlayer hydrogen bonds and π-π stacking interactions in an offset fashion to form a 3D supramolecular structure.

Ultrafine Vacancy-Rich Nb_(2)O_(5)Semiconductors Confined in Carbon Nanosheets Boost Dielectric Polarization for High-Attenuation Microwave Absorption

The integration of nano-semiconductors into electromagnetic wave absorption materials is a highly desirable strategy for intensifying dielectric polarization loss;achieving high-attenuation microwave absorption and realizing in-depth comprehension of dielectric loss mechanisms remain challenges.Herein,ultrafine oxygen vacancy-rich Nb_(2)O_(5)semiconductors are confined in carbon nanosheets(ov-Nb_(2)O_(5)/CNS)to boost dielectric polarization and achieve high attenuation.The polarization relaxation,electromagnetic response,and impedance matching of the ov-Nb_(2)O_(5)/CNS are significantly facilitated by the Nb_(2)O_(5)semiconductors with rich oxygen vacancies,which consequently realizes an extremely high attenuation performance of-80.8 dB(>99.999999%wave absorption)at 2.76 mm.As a dielectric polarization center,abundant Nb_(2)O_(5)–carbon heterointerfaces can intensify interfacial polarization loss to strengthen dielectric polarization,and the presence of oxygen vacancies endows Nb_(2)O_(5)semiconductors with abundant charge separation sites to reinforce electric dipole polarization.Moreover,the three-dimensional reconstruction of the absorber using microcomputer tomography technology provides insight into the intensification of the unique lamellar morphology regarding multiple reflection and scattering dissipation characteristics.Additionally,ov-Nb_(2)O_(5)/CNS demonstrates excellent application potential by curing into a microwave-absorbing,machinable,and heat-dissipating plate.This work provides insight into the dielectric polarization loss mechanisms of nano-semiconductor/carbon composites and inspires the design of high-performance microwave absorption materials.

Cobalt-catalyzed divergent functionalization of N-sulfonyl amines via β-carbon elimination

This article demonstrates a catalytic method for C(aryl)-C(alkyl) bond functionalization of N-sulfonyl amines. A cobalt(III)catalyst was used to cleave the C-C bond via β-carbon elimination, providing a metallacycle intermediate. Subsequent allylation,amidation, or alkenylation of the intermediate led to divergent conversions in the presence of diverse coupling partners. when the coupling partner was a diene, an insertion-type functionalization was realized with an exclusive 1,3-regioselectivity, in which both of the fragments derived from N-sulfonyl amines were utilized.

Challenges and prospects of lithium-CO_(2) batteries

The key role played by carbon dioxide in global temperature cycles has stimulated constant research attention on carbon capture and storage.Among the various options,lithium-carbon dioxide batteries are intriguing,not only for the transformation of waste carbon dioxide to value-added products,but also for the storage of electricity from renewable power resources and balancing the carbon cycle.The development of this system is still in its early stages and faces tremendous hurdles caused by the introduction of carbon dioxide.In this review,detailed discussion on the critical problems faced by the electrode,the interface,and the electrolyte is provided,along with the rational strategies required to address these problematic issues for efficient carbon dioxide fixation and conversion.We hope that this review will provide a resource for a comprehensive understanding of lithium-carbon dioxide batteries and will serve as guidance for exploring reversible and rechargeable alkali metal-based carbon dioxide battery systems in the future.