The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main resul...The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main results obtained can be summarized as follows: The cerium carbide CeC2 can be precipitated in cast steel and distributed along the grain boundaries. Heat treating the steel as austenite, the CeC2 transformed into ternary compound Fe4Ce4 C7, its thermodynamics of formation in steel being expressed as: ac exp(6400/T-6. 28), where 1015K<T<1523K and ac 0.126. Fe4Ce4C7 in steel is primitive tetragonal, anisotmpic in polarized light, opaque in dark field and a little greyer than iron matrix in bright field. Its Vickers hardness is about 420kg/mm2 (annealed) and 750kg/mm2 (quenched). This phase in steel is stable in basic and organic solutions and can be seperated from the matrix by electrolysis. Moreover, the LaC2 in steel can not be transformed into Fe-La-C ternary compound in present investigation.展开更多
A new concept of forming solid electrolyte interphases（SEI） in situ in an ionic conducting Li（1.5）Al（0.5）Ge（1.5）（PO4）3-polypropylene（LAGP-PP） based separator during charging and discharging is proposed and...A new concept of forming solid electrolyte interphases（SEI） in situ in an ionic conducting Li（1.5）Al（0.5）Ge（1.5）（PO4）3-polypropylene（LAGP-PP） based separator during charging and discharging is proposed and demonstrated. This unique structure shows a high ionic conductivity, low interface resistance with electrode, and can suppress the growth of lithium dendrite. The features of forming the SEI in situ are investigated by scanning electron microscopy（SEM） and x-ray photoelectron spectroscopy（XPS）. The results confirm that SEI films mainly consist of lithium fluoride and carbonates with various alkyl contents. The cell assembled by using the LAGP-coated separator demonstrates a good cycling performance even at high charging rates, and the lithium dendrites were not observed on the lithium metal electrode. Therefore, the SEI-LAGP-PP separator can be used as a promising flexible solid electrolyte for solid state lithium batteries.展开更多
Lithium-ion batteries(LIBs)are energy-storage devices with a high-energy density in which the separator provides a physical barrier between the cathode and anode,to prevent electrical short circuits.To meet the demand...Lithium-ion batteries(LIBs)are energy-storage devices with a high-energy density in which the separator provides a physical barrier between the cathode and anode,to prevent electrical short circuits.To meet the demands of high-performance batteries,the separator must have excellent electrolyte wettability,thermotolerance,mechanical strength,highly porous structures,and ionic conductivity.Numerous nonwoven-based separators have been used in LIBs due to their high porosity and large surface-to-volume ratios.However,the fabrication of multi-functional fibers,the construction of nonwoven separators,and their integration into energy-storage devices present grand challenges in fundamental theory and practical implementation.Herein,we systematically review the up-to-date concerning the design and preparation of nonwoven-based separators for LIBs.Recent progress in monolayer,composite,and solid electrolyte nonwoven-based separators and their fabrication strategies is discussed.Future challenges and directions toward advancements in separator technologies are also discussed to obtain separators with remarkable performance for high-energy density batteries.展开更多
文摘The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main results obtained can be summarized as follows: The cerium carbide CeC2 can be precipitated in cast steel and distributed along the grain boundaries. Heat treating the steel as austenite, the CeC2 transformed into ternary compound Fe4Ce4 C7, its thermodynamics of formation in steel being expressed as: ac exp(6400/T-6. 28), where 1015K<T<1523K and ac 0.126. Fe4Ce4C7 in steel is primitive tetragonal, anisotmpic in polarized light, opaque in dark field and a little greyer than iron matrix in bright field. Its Vickers hardness is about 420kg/mm2 (annealed) and 750kg/mm2 (quenched). This phase in steel is stable in basic and organic solutions and can be seperated from the matrix by electrolysis. Moreover, the LaC2 in steel can not be transformed into Fe-La-C ternary compound in present investigation.
基金Project supported by the Beijing Science and Technology ProjectChina(Grant No.Z13111000340000)+1 种基金the National Basic Research Program of China(Grant No.2012CB932900)the National Natural Science Foundation of China(Grant Nos.51325206 and 51421002)
文摘A new concept of forming solid electrolyte interphases（SEI） in situ in an ionic conducting Li（1.5）Al（0.5）Ge（1.5）（PO4）3-polypropylene（LAGP-PP） based separator during charging and discharging is proposed and demonstrated. This unique structure shows a high ionic conductivity, low interface resistance with electrode, and can suppress the growth of lithium dendrite. The features of forming the SEI in situ are investigated by scanning electron microscopy（SEM） and x-ray photoelectron spectroscopy（XPS）. The results confirm that SEI films mainly consist of lithium fluoride and carbonates with various alkyl contents. The cell assembled by using the LAGP-coated separator demonstrates a good cycling performance even at high charging rates, and the lithium dendrites were not observed on the lithium metal electrode. Therefore, the SEI-LAGP-PP separator can be used as a promising flexible solid electrolyte for solid state lithium batteries.
基金the National Key Research and Development Program of China(2022YFB3803502)the National Key Research and Development Program of China(22Z10303)+2 种基金the Fundamental Research Funds for the Central Universities(2232021D-21)the Open Project Program of High-Tech Organic Fibers Key Laboratory of Sichuan Province(No.PLN2022-11)Graduate Student Innovation Fund of Donghua University(BCZD2023003).
文摘Lithium-ion batteries(LIBs)are energy-storage devices with a high-energy density in which the separator provides a physical barrier between the cathode and anode,to prevent electrical short circuits.To meet the demands of high-performance batteries,the separator must have excellent electrolyte wettability,thermotolerance,mechanical strength,highly porous structures,and ionic conductivity.Numerous nonwoven-based separators have been used in LIBs due to their high porosity and large surface-to-volume ratios.However,the fabrication of multi-functional fibers,the construction of nonwoven separators,and their integration into energy-storage devices present grand challenges in fundamental theory and practical implementation.Herein,we systematically review the up-to-date concerning the design and preparation of nonwoven-based separators for LIBs.Recent progress in monolayer,composite,and solid electrolyte nonwoven-based separators and their fabrication strategies is discussed.Future challenges and directions toward advancements in separator technologies are also discussed to obtain separators with remarkable performance for high-energy density batteries.
