Ethylene carbonate(EC)is susceptible to the aggressive chemistry of nickel-rich cathodes,making it undesirable for high-voltage lithium-ion batteries(LIBs).The arbitrary elimination of EC leads to better oxidative tol...Ethylene carbonate(EC)is susceptible to the aggressive chemistry of nickel-rich cathodes,making it undesirable for high-voltage lithium-ion batteries(LIBs).The arbitrary elimination of EC leads to better oxidative tolerance but always incurs interfacial degradation and electrolyte decomposition.Herein,an EC-free electrolyte is deliberately developed based on gradient solvation by pairing solvation-protection agent(1,3,5-trifluorobenzene,F_(3)B)with propylene carbonate(PC)/methyl ethyl carbonate(EMC)formulation.F_(3)B keeps out of inner coordination shell but decomposes preferentially to construct robust interphase,inhibiting solvent decomposition and electrode corrosion.Thereby,the optimized electrolyte(1.1 M)with wide liquid range(-70–77℃)conveys decent interfacial compatibility and high-voltage stability(4.6 V for LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2),NCM622),qualifying reliable operation of practical NCM/graphite pouch cell(81.1%capacity retention over 600 cycles at 0.5 C).The solvation preservation and interface protection from F_(3)B blaze a new avenue for developing high-voltage electrolytes in next-generation LIBs.展开更多
解决110 k V阳山变电站两台主变压器并列运行时产生环流的问题。基于主变压器并列运行时环流产生的机理,对阳山变电站两台并列运行主变压器的运行台账、负荷数据、技术参数等进行分析,得出环流产生的主要原因是两台变压器35k V侧电压档...解决110 k V阳山变电站两台主变压器并列运行时产生环流的问题。基于主变压器并列运行时环流产生的机理,对阳山变电站两台并列运行主变压器的运行台账、负荷数据、技术参数等进行分析,得出环流产生的主要原因是两台变压器35k V侧电压档位不一致使得电压变比不同。现场检查结果显示:1号、2号主变压器35 k V侧电压档位分别处于5档和3档位置,由此验证了分析的准确性。在运行过程中,如发现两台并列运行的主变压器中压侧档位不一致,应尽快将主变压器分列运行或转检修后进行档位调整,以及时消除环流。展开更多
An on-chip voltage reference with a wide supply voltage range is required by some applications,especially that of power management （PM） controller chips applied to telecommunication, automotive, lighting equipment, ...An on-chip voltage reference with a wide supply voltage range is required by some applications,especially that of power management （PM） controller chips applied to telecommunication, automotive, lighting equipment, etc., when high power supply voltage is needed. Accordingly,a new bandgap reference with a wide supply voltage range is proposed. Due to the improved structure,it features a high power supply rejection ratio （PSRR） and high temperature stability. In addition, an auxiliary micro-power reference is introduced to support the sleep mode of the PM chip and reduce its standby power consumption. The auxiliary reference provides bias currents in normal mode and a 1.28V reference voltage in sleep mode to replace the main reference and save power. Simulation results show that the reference provides a reference volt- age of 1.27V,which has a 3.5mV drift over the temperature range from -20 to 120~C and 56t^V deviation over a supply voltage range from 3 to 40V. The PSRR is higher than 100dB for frequency below 10kHz. The circuit was completed in 1.5tzm BCD （Bipolar-CMOS-DMOS） technology. The experimental results show that all main expectations are achieved.展开更多
p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of ...p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of p-GaN limit the further improvement of device performance.Thus,the more cost-effective cap layer has attracted wide attention in GaN-based HEMT.In this paper,p-type tin monoxide(p-SnO)was firstly investigated as a gate cap to realize E-mode AlGaN/GaN HEMT by both Silvaco simulation and experiment.Simulation results show that by simply adjusting the thickness(50 to 200 nm)or the doping concentration(3×10^(17)to 3×10^(18)cm^(-3))of p-SnO,the threshold voltage(V_(th))of HEMT can be continuously adjusted in the range from zero to 10 V.Simultaneously,the device demonstrated a drain current density above 120 mA mm^(-1),a gate breakdown voltage(V_(BG))of 7.5 V and a device breakdown voltage(V_(B))of 2470 V.What is more,the etching-free AlGaN/GaN HEMT with sputtered p-SnO gate cap were fabricated,and achieved a positive V_(th) of 1 V,V_(BG) of 4.2 V and V_(B) of 420 V,which confirms the application potential of the p-SnO film as a gate cap layer for E-mode GaN-based HEMT.This work is instructive to the design and manufacture of p-oxide gate cap E-mode AlGaN/GaN HEMT with low cost.展开更多
基于功率为4.5 k W燃料电池堆的台架动态循环工况试验,研究质子交换膜燃料电池(PEMFC)堆单体电池电压的一致性。选用熵值法对循环工况中的电流密度进行权重分析,选出开路电压、怠速功率、15%额定功率及额定功率对应的特征电流密度,并对...基于功率为4.5 k W燃料电池堆的台架动态循环工况试验,研究质子交换膜燃料电池(PEMFC)堆单体电池电压的一致性。选用熵值法对循环工况中的电流密度进行权重分析,选出开路电压、怠速功率、15%额定功率及额定功率对应的特征电流密度,并对单体电池电压一致性变化规律进行整体分析,验证特征电流密度可替代循环工况中的不同电流密度点,反映单体电池的电压一致性。利用统计学参数变异系数和相对极差来衡量单体电池的电压一致性,发现在大电流密度及长时间运行时,电压一致性明显变差。性能最差时,变异系数为3.1%,相对极差为9.4%。展开更多
Through tailoring interfacial chemistry,electrolyte engineering is a facile yet effective strategy for highperformance lithium(Li)metal batteries,where the solvation structure is critical for interfacial chemistry.Her...Through tailoring interfacial chemistry,electrolyte engineering is a facile yet effective strategy for highperformance lithium(Li)metal batteries,where the solvation structure is critical for interfacial chemistry.Herein,the effect of electrostatic interaction on regulating an anion-rich solvation is firstly proposed.The moderate electrostatic interaction between anion and solvent promotes anion to enter the solvation sheath,inducing stable solid electrolyte interphase with fast Li+transport kinetics on the anode.This asdesigned electrolyte exhibits excellent compatibility with Li metal anode(a Li deposition/stripping Coulombic efficiency of 99.3%)and high-voltage LiCoO_(2) cathode.Consequently,the 50μm-thin Li||high-loading LiCoO_(2) cells achieve significantly improved cycling performance under stringent conditions of high voltage over 4.5 V,lean electrolyte,and wide temperature range(-20 to 60℃).This work inspires a groundbreaking strategy to manipulate the solvation structure through regulating the interactions of solvent and anion for highperformance Li metal batteries.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFB2404800)。
文摘Ethylene carbonate(EC)is susceptible to the aggressive chemistry of nickel-rich cathodes,making it undesirable for high-voltage lithium-ion batteries(LIBs).The arbitrary elimination of EC leads to better oxidative tolerance but always incurs interfacial degradation and electrolyte decomposition.Herein,an EC-free electrolyte is deliberately developed based on gradient solvation by pairing solvation-protection agent(1,3,5-trifluorobenzene,F_(3)B)with propylene carbonate(PC)/methyl ethyl carbonate(EMC)formulation.F_(3)B keeps out of inner coordination shell but decomposes preferentially to construct robust interphase,inhibiting solvent decomposition and electrode corrosion.Thereby,the optimized electrolyte(1.1 M)with wide liquid range(-70–77℃)conveys decent interfacial compatibility and high-voltage stability(4.6 V for LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2),NCM622),qualifying reliable operation of practical NCM/graphite pouch cell(81.1%capacity retention over 600 cycles at 0.5 C).The solvation preservation and interface protection from F_(3)B blaze a new avenue for developing high-voltage electrolytes in next-generation LIBs.
文摘解决110 k V阳山变电站两台主变压器并列运行时产生环流的问题。基于主变压器并列运行时环流产生的机理,对阳山变电站两台并列运行主变压器的运行台账、负荷数据、技术参数等进行分析,得出环流产生的主要原因是两台变压器35k V侧电压档位不一致使得电压变比不同。现场检查结果显示:1号、2号主变压器35 k V侧电压档位分别处于5档和3档位置,由此验证了分析的准确性。在运行过程中,如发现两台并列运行的主变压器中压侧档位不一致,应尽快将主变压器分列运行或转检修后进行档位调整,以及时消除环流。
文摘An on-chip voltage reference with a wide supply voltage range is required by some applications,especially that of power management （PM） controller chips applied to telecommunication, automotive, lighting equipment, etc., when high power supply voltage is needed. Accordingly,a new bandgap reference with a wide supply voltage range is proposed. Due to the improved structure,it features a high power supply rejection ratio （PSRR） and high temperature stability. In addition, an auxiliary micro-power reference is introduced to support the sleep mode of the PM chip and reduce its standby power consumption. The auxiliary reference provides bias currents in normal mode and a 1.28V reference voltage in sleep mode to replace the main reference and save power. Simulation results show that the reference provides a reference volt- age of 1.27V,which has a 3.5mV drift over the temperature range from -20 to 120~C and 56t^V deviation over a supply voltage range from 3 to 40V. The PSRR is higher than 100dB for frequency below 10kHz. The circuit was completed in 1.5tzm BCD （Bipolar-CMOS-DMOS） technology. The experimental results show that all main expectations are achieved.
基金supported by the National Natural Science Foundation of China(62003151,61925404,62074122,and 61904139)the Key Research and Development Program in Shaanxi Province(2016KTZDGY-03-01)。
文摘p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of p-GaN limit the further improvement of device performance.Thus,the more cost-effective cap layer has attracted wide attention in GaN-based HEMT.In this paper,p-type tin monoxide(p-SnO)was firstly investigated as a gate cap to realize E-mode AlGaN/GaN HEMT by both Silvaco simulation and experiment.Simulation results show that by simply adjusting the thickness(50 to 200 nm)or the doping concentration(3×10^(17)to 3×10^(18)cm^(-3))of p-SnO,the threshold voltage(V_(th))of HEMT can be continuously adjusted in the range from zero to 10 V.Simultaneously,the device demonstrated a drain current density above 120 mA mm^(-1),a gate breakdown voltage(V_(BG))of 7.5 V and a device breakdown voltage(V_(B))of 2470 V.What is more,the etching-free AlGaN/GaN HEMT with sputtered p-SnO gate cap were fabricated,and achieved a positive V_(th) of 1 V,V_(BG) of 4.2 V and V_(B) of 420 V,which confirms the application potential of the p-SnO film as a gate cap layer for E-mode GaN-based HEMT.This work is instructive to the design and manufacture of p-oxide gate cap E-mode AlGaN/GaN HEMT with low cost.
文摘基于功率为4.5 k W燃料电池堆的台架动态循环工况试验,研究质子交换膜燃料电池(PEMFC)堆单体电池电压的一致性。选用熵值法对循环工况中的电流密度进行权重分析,选出开路电压、怠速功率、15%额定功率及额定功率对应的特征电流密度,并对单体电池电压一致性变化规律进行整体分析,验证特征电流密度可替代循环工况中的不同电流密度点,反映单体电池的电压一致性。利用统计学参数变异系数和相对极差来衡量单体电池的电压一致性,发现在大电流密度及长时间运行时,电压一致性明显变差。性能最差时,变异系数为3.1%,相对极差为9.4%。
基金supported by National Nature Science Foundation of China(No.51872157 and No.52072208)National Key R&D Program of China 2021YFA1202802Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N111)。
文摘Through tailoring interfacial chemistry,electrolyte engineering is a facile yet effective strategy for highperformance lithium(Li)metal batteries,where the solvation structure is critical for interfacial chemistry.Herein,the effect of electrostatic interaction on regulating an anion-rich solvation is firstly proposed.The moderate electrostatic interaction between anion and solvent promotes anion to enter the solvation sheath,inducing stable solid electrolyte interphase with fast Li+transport kinetics on the anode.This asdesigned electrolyte exhibits excellent compatibility with Li metal anode(a Li deposition/stripping Coulombic efficiency of 99.3%)and high-voltage LiCoO_(2) cathode.Consequently,the 50μm-thin Li||high-loading LiCoO_(2) cells achieve significantly improved cycling performance under stringent conditions of high voltage over 4.5 V,lean electrolyte,and wide temperature range(-20 to 60℃).This work inspires a groundbreaking strategy to manipulate the solvation structure through regulating the interactions of solvent and anion for highperformance Li metal batteries.
