通过与电喷雾质谱(Electrospray ionization mass spectrometry,ESI-MS)对比的方式,对高电压辅助激光解吸附离子化质谱(High-voltage-assisted laser desorption ionization mass spectrometry,HALDI-MS)中的盐效应进行了研究。在正、...通过与电喷雾质谱(Electrospray ionization mass spectrometry,ESI-MS)对比的方式,对高电压辅助激光解吸附离子化质谱(High-voltage-assisted laser desorption ionization mass spectrometry,HALDI-MS)中的盐效应进行了研究。在正、负离子模式下,分别以L-酪氨酸、β-环糊精、α-硫辛酸以及α-硫辛酸-β-环糊精复合体系为例,对比分析了加盐前后所得的ESI-MS和HALDI-MS谱图,发现HALDI-MS比ESI-MS具有更高的盐容忍度。本实验还发现在HALDI-MS中加入适量盐会引起α-硫辛酸与β-环糊精络合离子信号增强的特殊现象,并提出了产生这种信号增强作用的原因是溶液中盐类阳离子与α-硫辛酸-β-环糊精复合体系形成了三元复合物。展开更多
A precise theoretical calculation off the pinch of voltage of the box-like ion implantation 4H-SiC MESFETs is investigated with the consideration of the effects of the ion-implanted channel and the depth of MESFETs ch...A precise theoretical calculation off the pinch of voltage of the box-like ion implantation 4H-SiC MESFETs is investigated with the consideration of the effects of the ion-implanted channel and the depth of MESFETs channel.The implant depth profile is simulated using the Monte Carlo simulator TRIM.The effects of parameters such as temperature,acceptor density,and activation rate on channel depth a,pinch off voltage are studied.展开更多
Based on orthogonal experiments,the effects of voltage,frequency,duty ratio and their interactions on the thickness and corrosion resistance of coatings prepared by plasma electrolytic oxidation(PEO)on aluminum in an ...Based on orthogonal experiments,the effects of voltage,frequency,duty ratio and their interactions on the thickness and corrosion resistance of coatings prepared by plasma electrolytic oxidation(PEO)on aluminum in an alkaline silicate-containing electrolyte were investigated.The thicknesses of these coatings were obtained by measuring their cross-section using Image J software.Their corrosion resistances were evaluated in HCl and NaCl media through spot test and electrochemical test.The results show that the experimental design of this study is the key to investigate the interactions among these electrical parameters.Additionally,not only each independent factor,but also their interactions exhibit a remarkable influence on the coatings.The combination of high voltage,low frequency and large duty ratio significantly increases the coating thickness and content of the corrosion resistance phase,and thus improves the corrosion resistance of the coating in HNO3 medium.Conversely,the coating possessing the densest microstructure and best corrosion resistance in NaCl medium is obtained when low voltage and high frequency match with a small duty ratio.展开更多
Thermal runaway has been a long-standing safety issue impeding the development of high-energy- density batteries. Physical safety designs such as employing circuit-breakers and fuses to batteries are limited by small ...Thermal runaway has been a long-standing safety issue impeding the development of high-energy- density batteries. Physical safety designs such as employing circuit-breakers and fuses to batteries are limited by small operating voltage windows and no resumption of original working condition when it is cooled down. Here we report a smart thermoresponsive polymer electrolyte that can be incorporated inside batteries to prevent thermal runaway via a fast and reversible sol-gel transition, and successfully combine this smart electrolyte with a rechargeable Zn/^-Mn02 battery system. At high temperature, bat- tery operation is inhibited as a result of the increased internal resistance caused by the gelation of liquid electrolyte. After cooling down, the electrolyte is spontaneously reversed to sol state and the electro- chemical performance of the battery is restored. More importantly, sol-gel transition enables the smart battery to experience different charge-discharge rates under various temperature levels, providing a smart and active strategy to achieve dynamic and reversible self-protection.展开更多
Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea...Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea-based polyimide/reduced graphene oxide(PNTCSA/RGO)composite was synthesized via a condensation polymerization method.As a cathode material in lithium-ion batteries,excellent performance is demonstrated with high reversible capacity(144.2 mA h g^−1),high discharge voltage(∼2.5 V),and long cycling life(over 2000 cycles at 500 mA g^−1),which are comparable to those of other well documented in organic electrodes.Encouraging electrochemical performance is also demonstrated for sodium ion batteries(a cycling life of 800 cycles at 500 mA g^−1),while poor performance is delivered in potassium ion batteries.Theoretical studies reveal that the active sites are carbonyl groups for all alkali ions but one inserted alkali metal ion is shared by two carbonyl groups from the two neighbor units.More importantly,K ions have stronger interaction with S atoms than Li/Na ions,which may lead to poor structure reversibility and account for the poor cycling performance.Our findings provide a fundamental understanding of polyimide based polymer electrodes and help to design and develop high performance organic electrode materials for alkali metal ion batteries.展开更多
文摘通过与电喷雾质谱(Electrospray ionization mass spectrometry,ESI-MS)对比的方式,对高电压辅助激光解吸附离子化质谱(High-voltage-assisted laser desorption ionization mass spectrometry,HALDI-MS)中的盐效应进行了研究。在正、负离子模式下,分别以L-酪氨酸、β-环糊精、α-硫辛酸以及α-硫辛酸-β-环糊精复合体系为例,对比分析了加盐前后所得的ESI-MS和HALDI-MS谱图,发现HALDI-MS比ESI-MS具有更高的盐容忍度。本实验还发现在HALDI-MS中加入适量盐会引起α-硫辛酸与β-环糊精络合离子信号增强的特殊现象,并提出了产生这种信号增强作用的原因是溶液中盐类阳离子与α-硫辛酸-β-环糊精复合体系形成了三元复合物。
文摘A precise theoretical calculation off the pinch of voltage of the box-like ion implantation 4H-SiC MESFETs is investigated with the consideration of the effects of the ion-implanted channel and the depth of MESFETs channel.The implant depth profile is simulated using the Monte Carlo simulator TRIM.The effects of parameters such as temperature,acceptor density,and activation rate on channel depth a,pinch off voltage are studied.
基金Project(1111RJDA011)supported by the Creative Research Group Fund of Gansu Province,ChinaProject(SKLAB02015006)supported by the State Key Laboratory Open Fund of Advanced Processing and Recycling of Nonferrous Metals,China。
文摘Based on orthogonal experiments,the effects of voltage,frequency,duty ratio and their interactions on the thickness and corrosion resistance of coatings prepared by plasma electrolytic oxidation(PEO)on aluminum in an alkaline silicate-containing electrolyte were investigated.The thicknesses of these coatings were obtained by measuring their cross-section using Image J software.Their corrosion resistances were evaluated in HCl and NaCl media through spot test and electrochemical test.The results show that the experimental design of this study is the key to investigate the interactions among these electrical parameters.Additionally,not only each independent factor,but also their interactions exhibit a remarkable influence on the coatings.The combination of high voltage,low frequency and large duty ratio significantly increases the coating thickness and content of the corrosion resistance phase,and thus improves the corrosion resistance of the coating in HNO3 medium.Conversely,the coating possessing the densest microstructure and best corrosion resistance in NaCl medium is obtained when low voltage and high frequency match with a small duty ratio.
基金supported by NSFC/RGC Joint Research Scheme under Project N_CityU123/15 and NSFC 5151101197a Grant from City University of Hong Kong (PJ7004645)sponsored by Science & Technology Department of Sichuan Province (2017JY0088)
文摘Thermal runaway has been a long-standing safety issue impeding the development of high-energy- density batteries. Physical safety designs such as employing circuit-breakers and fuses to batteries are limited by small operating voltage windows and no resumption of original working condition when it is cooled down. Here we report a smart thermoresponsive polymer electrolyte that can be incorporated inside batteries to prevent thermal runaway via a fast and reversible sol-gel transition, and successfully combine this smart electrolyte with a rechargeable Zn/^-Mn02 battery system. At high temperature, bat- tery operation is inhibited as a result of the increased internal resistance caused by the gelation of liquid electrolyte. After cooling down, the electrolyte is spontaneously reversed to sol state and the electro- chemical performance of the battery is restored. More importantly, sol-gel transition enables the smart battery to experience different charge-discharge rates under various temperature levels, providing a smart and active strategy to achieve dynamic and reversible self-protection.
基金This work was financially supported by the National Natural Science Foundation of China(51672188 and 21703036).
文摘Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea-based polyimide/reduced graphene oxide(PNTCSA/RGO)composite was synthesized via a condensation polymerization method.As a cathode material in lithium-ion batteries,excellent performance is demonstrated with high reversible capacity(144.2 mA h g^−1),high discharge voltage(∼2.5 V),and long cycling life(over 2000 cycles at 500 mA g^−1),which are comparable to those of other well documented in organic electrodes.Encouraging electrochemical performance is also demonstrated for sodium ion batteries(a cycling life of 800 cycles at 500 mA g^−1),while poor performance is delivered in potassium ion batteries.Theoretical studies reveal that the active sites are carbonyl groups for all alkali ions but one inserted alkali metal ion is shared by two carbonyl groups from the two neighbor units.More importantly,K ions have stronger interaction with S atoms than Li/Na ions,which may lead to poor structure reversibility and account for the poor cycling performance.Our findings provide a fundamental understanding of polyimide based polymer electrodes and help to design and develop high performance organic electrode materials for alkali metal ion batteries.
