High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high el...High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high electric field could affect the capacitor lifetime, and this effect on metallized polypropylene film capacitors (MPPFCs) in pulsed-power applications is studied and presented. Experimental re- sults show that the lifetime of MPPFCs decreases with the increasing peak value of charged electric field, and this decrease could be described by function (L/L0) ∝ (E/E0)–m, where, m=7.32. The lifetime of MPPFCs also decreases with the increase of the reversal coeffi- cients in underdamped circuits, which could be described by (L/L0) ∝ (ln(1/K0)/(ln(1/K))–b, where, b=0.7. These results provide a basis for the lifetime prediction of MPPFCs in pulsed-power applications.展开更多
Metallised film capacitors(MFCs)are renowned for their unique self-healing(SH)properties,which bestow them with exceptional reliability and stability in the face of intense electric fields,high voltages,and pulse powe...Metallised film capacitors(MFCs)are renowned for their unique self-healing(SH)properties,which bestow them with exceptional reliability and stability in the face of intense electric fields,high voltages,and pulse power applications.Nonetheless,the exploration of SH characteristics concerning single-layer dielectric film remains insufficient for advancing MFC reliability evaluation.To establish the theoretical correlation of SH characteristics from the device to the film in the MFCs,this work developed a simulation model to analyse the SH dynamic behaviour in the MFCs.The effects of coupling capacitors,arc resistance and insulation resistance on the macroscopic characteristics(voltage drop and pulse current)are focused during the SH process in MFCs.The results indicate that SH is primarily associated with the voltage drop duration rather than the sampling current.Consequently,the SH process in MFC is characterised as an abrupt decrease in voltage to its minimum value.This refinement enhances the SH energy dissipation model of MFC.The quantified relationship between the macroscopic characteristics and microstructure evolution(polypropylene decomposition and aluminium electrode vaporisation)is established in MFCs under diverse SH energy levels.As SH energy and duration increase,the proportion of energy attributed to polypropylene decomposition increases,resulting in multi-layer ablation and adhesion within the metallised film and a pronounced deterioration in MFC electrical performance.The examination of macro-micro perspectives sheds new light on the intricate mechanisms governing the SH behaviour in MFCs,offering valuable insights for the advancement of their design,reliability evaluation,and performance optimisation in diverse electrical applications.展开更多
Ensuring reliable and safe operation of high-power electronic devices necessitates the development of high-quality dielectric nano-capacitors with high recoverable energy density(URec)and efficiency(η)at low applied ...Ensuring reliable and safe operation of high-power electronic devices necessitates the development of high-quality dielectric nano-capacitors with high recoverable energy density(URec)and efficiency(η)at low applied electric fields(E)/voltages.In this work,we demonstrate ultra-high URec andηat low E<500 kV/cm in as-grown epitaxial relaxor ferroelectric(RFE)PMN-33PT films,rivaling those typically achieved in state-of-the-art RFE and antiferroelectric(AFE)materials.The high energy storage properties were achieved using a synergistic strategy involving large polarization,a giant built-in potential/imprint(five times higher than the coercive field),and AFE like behavior.The structural,chemical,and electrical investigations revealed that these achievements mainly arise from the effects of strain,dipole defects,and chemical composition.For instance,at low E,the capacitors exhibit under 160 kV/cm(i.e.,8 V)and 400 kV/cm(i.e.,20 V),respectively,an ultra-highΔP(45μC/cm^(2)and 60μC/cm^(2)),UE=URec/E(21 J·MV/cm^(2)and 17 J·MV/cm^(2)),and UF=URec/(1-η)(20 J/cm^(3)and 47 J/cm^(3))with a robust charge-discharge fatigue endurance and outstanding frequency and thermal stability.Additionally,the designed films exhibit outstanding energy storage performance at higher E up to 2 MV/cm(ΔP≈78μC/cm^(2),UE≈17.3 J·MV/cm^(2)and UF≈288 J/cm^(3))due to their low leakage current density.展开更多
The Cl2-sensitive heteropolysiloxanes(HPS) film was formed on the interdigital capacitor based on silicon dioxide by means of sol-gel process and spin-on technique.Measurements of interdigital capacitance were perform...The Cl2-sensitive heteropolysiloxanes(HPS) film was formed on the interdigital capacitor based on silicon dioxide by means of sol-gel process and spin-on technique.Measurements of interdigital capacitance were performed at room temperature for frequencies 100 Hz,1 kHz and 10 kHz.It is shown that there is a linear relationship between the capacitance and the concentration of chlorine gas.Influences of the measurement frequency and film thickness of silicate on the sensitivity of the sensor to C12 gas were discussed.And organically modified N,N-diethylaminopropyl-trimethoxysilane (APMS) had a much higher sensitivity.展开更多
The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge e...The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material.However,it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously.Considering that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)films.By revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from electrodes.Worthy to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin layer.In addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.展开更多
基金Project supported by Opening Foundation of National Engineering Laboratory for UltraHigh Voltage Engineering Technology (Kunming, Guangzhou, China)
文摘High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high electric field could affect the capacitor lifetime, and this effect on metallized polypropylene film capacitors (MPPFCs) in pulsed-power applications is studied and presented. Experimental re- sults show that the lifetime of MPPFCs decreases with the increasing peak value of charged electric field, and this decrease could be described by function (L/L0) ∝ (E/E0)–m, where, m=7.32. The lifetime of MPPFCs also decreases with the increase of the reversal coeffi- cients in underdamped circuits, which could be described by (L/L0) ∝ (ln(1/K0)/(ln(1/K))–b, where, b=0.7. These results provide a basis for the lifetime prediction of MPPFCs in pulsed-power applications.
基金Major Research Plan of the National Natural Science Foundation of China,Grant/Award Numbers:92166206,92366302Science and Technology Projects of Hunan Province,Grant/Award Number:2024JJ6051。
文摘Metallised film capacitors(MFCs)are renowned for their unique self-healing(SH)properties,which bestow them with exceptional reliability and stability in the face of intense electric fields,high voltages,and pulse power applications.Nonetheless,the exploration of SH characteristics concerning single-layer dielectric film remains insufficient for advancing MFC reliability evaluation.To establish the theoretical correlation of SH characteristics from the device to the film in the MFCs,this work developed a simulation model to analyse the SH dynamic behaviour in the MFCs.The effects of coupling capacitors,arc resistance and insulation resistance on the macroscopic characteristics(voltage drop and pulse current)are focused during the SH process in MFCs.The results indicate that SH is primarily associated with the voltage drop duration rather than the sampling current.Consequently,the SH process in MFC is characterised as an abrupt decrease in voltage to its minimum value.This refinement enhances the SH energy dissipation model of MFC.The quantified relationship between the macroscopic characteristics and microstructure evolution(polypropylene decomposition and aluminium electrode vaporisation)is established in MFCs under diverse SH energy levels.As SH energy and duration increase,the proportion of energy attributed to polypropylene decomposition increases,resulting in multi-layer ablation and adhesion within the metallised film and a pronounced deterioration in MFC electrical performance.The examination of macro-micro perspectives sheds new light on the intricate mechanisms governing the SH behaviour in MFCs,offering valuable insights for the advancement of their design,reliability evaluation,and performance optimisation in diverse electrical applications.
基金supported by the Slovenian Research Agency(Nos.P2-0091,J2-2510,N2-0187,N2-0149,and P1-0125)the Swiss National Science Foundation(Lead Agency Grant No.192047)the Region Hauts-de-France(Projects TERRA(AAP STARS-N°21002758)and TRANSITION(CPER MANIFEST-N°22006563)).
文摘Ensuring reliable and safe operation of high-power electronic devices necessitates the development of high-quality dielectric nano-capacitors with high recoverable energy density(URec)and efficiency(η)at low applied electric fields(E)/voltages.In this work,we demonstrate ultra-high URec andηat low E<500 kV/cm in as-grown epitaxial relaxor ferroelectric(RFE)PMN-33PT films,rivaling those typically achieved in state-of-the-art RFE and antiferroelectric(AFE)materials.The high energy storage properties were achieved using a synergistic strategy involving large polarization,a giant built-in potential/imprint(five times higher than the coercive field),and AFE like behavior.The structural,chemical,and electrical investigations revealed that these achievements mainly arise from the effects of strain,dipole defects,and chemical composition.For instance,at low E,the capacitors exhibit under 160 kV/cm(i.e.,8 V)and 400 kV/cm(i.e.,20 V),respectively,an ultra-highΔP(45μC/cm^(2)and 60μC/cm^(2)),UE=URec/E(21 J·MV/cm^(2)and 17 J·MV/cm^(2)),and UF=URec/(1-η)(20 J/cm^(3)and 47 J/cm^(3))with a robust charge-discharge fatigue endurance and outstanding frequency and thermal stability.Additionally,the designed films exhibit outstanding energy storage performance at higher E up to 2 MV/cm(ΔP≈78μC/cm^(2),UE≈17.3 J·MV/cm^(2)and UF≈288 J/cm^(3))due to their low leakage current density.
文摘The Cl2-sensitive heteropolysiloxanes(HPS) film was formed on the interdigital capacitor based on silicon dioxide by means of sol-gel process and spin-on technique.Measurements of interdigital capacitance were performed at room temperature for frequencies 100 Hz,1 kHz and 10 kHz.It is shown that there is a linear relationship between the capacitance and the concentration of chlorine gas.Influences of the measurement frequency and film thickness of silicate on the sensitivity of the sensor to C12 gas were discussed.And organically modified N,N-diethylaminopropyl-trimethoxysilane (APMS) had a much higher sensitivity.
基金supported by the National Natural Science Foundation of China(Grant Nos.51937007,and 51921005)National Key Research and Development Program of China(No.2021YFB2401502).
文摘The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material.However,it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously.Considering that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)films.By revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from electrodes.Worthy to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin layer.In addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.
