Polymer-ceramic composites were prepared by twin screw melt extrusion with high-density polyethylene (HDPE) as the matrix and polystyrene-coated BaO-Nd2O3-TiO2 (BNT) ceramics as the filling material.Interestingly,the ...Polymer-ceramic composites were prepared by twin screw melt extrusion with high-density polyethylene (HDPE) as the matrix and polystyrene-coated BaO-Nd2O3-TiO2 (BNT) ceramics as the filling material.Interestingly,the incorporation of polystyrene (PS) by the coating route could significantly improve the thermal behaviors of the composites (HDPE-PS/BNT),besides the temperature stability of dielectric properties and thermal displacement.The microwave dielectric properties of the composites were investigated systematically.The results indicated that,as the volume fraction of BNT ceramic particles increased from 10 to 50 vol％ in the composites,the dielectric constant increased from 3.54 (9.23 GHz) to 13.14 (7.20 GHz),which can be beneficial for the miniaturization of microwave devices;the dielectric loss tangent was relatively low (0.0003-0.0012);more importantly,the ratio of PS to HDPE increased accordingly,making the composite containing 50 vol％ BNT ceramics have a low value of temperature coefficient of resonant frequency (τf =-11.2 ppm/℃) from-20 to 60 ℃.The GPS microstrip antennas were therefore designed and prepared from the HDPE-PS/BNT composites.They possessed good thermal stability (τf=23.6 ppm/℃) over a temperature range of-20 to 60 ℃,promising to meet the requirements of practical antenna applications.展开更多
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 io...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.展开更多
The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecula...The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecular weight,and the polydispersivity index of the synthesized PCS are SiC_(1.94)H_(5.01)O_(0.028),1135,and 1.66,respectively,which can be attributed to the higher reaction temperature used for polymerization.The polymer to ceramic conversion of PCS was completed at 900℃with a ceramic yield of 85%.The crystallization started at 1100℃,and at 1200℃,well resolved peaks ofβ-SiC were formed with small amount ofα-cristobalite.The X-ray diffraction(XRD)and transmission electron microscopy(TEM)studies indicated the presence of nanocrystallineβ-SiC.展开更多
基金the National Natural Science Foundation of China，the Ministry of Science and Technology of China through 973 Program under Grant No.2015CB654605,and Tsinghua National Laboratory for Information Science and Technology (TNList)Cross-discipline Foundation
文摘Polymer-ceramic composites were prepared by twin screw melt extrusion with high-density polyethylene (HDPE) as the matrix and polystyrene-coated BaO-Nd2O3-TiO2 (BNT) ceramics as the filling material.Interestingly,the incorporation of polystyrene (PS) by the coating route could significantly improve the thermal behaviors of the composites (HDPE-PS/BNT),besides the temperature stability of dielectric properties and thermal displacement.The microwave dielectric properties of the composites were investigated systematically.The results indicated that,as the volume fraction of BNT ceramic particles increased from 10 to 50 vol％ in the composites,the dielectric constant increased from 3.54 (9.23 GHz) to 13.14 (7.20 GHz),which can be beneficial for the miniaturization of microwave devices;the dielectric loss tangent was relatively low (0.0003-0.0012);more importantly,the ratio of PS to HDPE increased accordingly,making the composite containing 50 vol％ BNT ceramics have a low value of temperature coefficient of resonant frequency (τf =-11.2 ppm/℃) from-20 to 60 ℃.The GPS microstrip antennas were therefore designed and prepared from the HDPE-PS/BNT composites.They possessed good thermal stability (τf=23.6 ppm/℃) over a temperature range of-20 to 60 ℃,promising to meet the requirements of practical antenna applications.
基金financially supported by the National Natural Science Foundation of China(Nos.21701083 and 51801078)the Zhenjiang Key Laboratory of Marine Power Equipment Performance(No.SS2018006)+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Nos.SJCX19_0612 and KYCX20_3137)the Project of Jiangsu University(High-Tech Ship)Collaborative Innovation Center(No.2019,1174871801-11).
文摘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.
文摘The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecular weight,and the polydispersivity index of the synthesized PCS are SiC_(1.94)H_(5.01)O_(0.028),1135,and 1.66,respectively,which can be attributed to the higher reaction temperature used for polymerization.The polymer to ceramic conversion of PCS was completed at 900℃with a ceramic yield of 85%.The crystallization started at 1100℃,and at 1200℃,well resolved peaks ofβ-SiC were formed with small amount ofα-cristobalite.The X-ray diffraction(XRD)and transmission electron microscopy(TEM)studies indicated the presence of nanocrystallineβ-SiC.
