Sulfur-doped iron-cobalt tannate nanorods(S-FeCoTA)derived from metal-organic frameworks(MOFs)as electrocatalysts were synthesized via a one-step hydrothermal method.The optimized S-FeCoTA was interlaced by loose nano...Sulfur-doped iron-cobalt tannate nanorods(S-FeCoTA)derived from metal-organic frameworks(MOFs)as electrocatalysts were synthesized via a one-step hydrothermal method.The optimized S-FeCoTA was interlaced by loose nanorods,which had many voids.The S-FeCoTA catalysts exhibited excellent electrochemical oxygen evolution reaction(OER)performance with a low overpotential of 273 mV at 10 mA·cm^(-2)and a small Tafel slope of 36 mV·dec^(-1)in 1 mol·L^(-1)KOH.The potential remained at 1.48 V(vs RHE)at 10 mA·cm^(-2)under continuous testing for 15 h,implying that S-FeCoTA had good stability.The Faraday efficiency of S-FeCoTA was 94%.The outstanding OER activity of S-FeCoTA is attributed to the synergistic effects among S,Fe,and Co,thus promoting electron transfer,reducing the reaction kinetic barrier,and enhancing the OER performance.展开更多
Sulfide solid electrolytes(S-SEs)are widely preferred for their high ionic conductivity and processability.However,the further development of S-SEs is hindered by the excessive price of its critical raw materials of L...Sulfide solid electrolytes(S-SEs)are widely preferred for their high ionic conductivity and processability.However,the further development of S-SEs is hindered by the excessive price of its critical raw materials of Li_(2)S.Herein,a low-cost and environmentally friendly method is proposed to synthesize Li_(2)S by the carbothermal reduction reaction of Li_(2)SO_(4)in one step,and the effects of various factors are also discussed.As a result,a purity of 99.67%is obtained over the self-prepared Li_(2)S.More importantly,the cost of the self-prepared Li_(2)S is only about 50$/kg,which is significantly lower than that of the commercial counterpart(10000−15000 dollar/kg).Moreover,the ionic conductivity of Li_(5.5)PS_(4.5)Cl_(1.5)prepared using self-prepared Li_(2)S as raw materials is 4.19 mS/cm at room temperature,which is a little higher than that of Li_(5.5)PS_(4.5)Cl_(1.5)using commercial Li_(2)S(4.05 mS/cm).And the all-solid-state lithium batteries(ASSLBs)with the as-prepared electrolytes could maintain a discharge capacity of 109.9 mA·h/g with an average coulombic efficiency(CE)of 98%after 100 cycles at 0.2 C,which is equivalent to that using commercial Li_(2)S,demonstrating that the preparation strategy of Li_(2)S proposed in this work is feasible.展开更多
针对电网故障下的双馈风力发电机组(Doubly-Fed Induction Generations,DFIG)的低电压穿越问题,提出装设电阻型高温超导故障限流器(High Temperature Superconducting Fault Current limiter,HTS-FCL)的低电压穿越保护策略。基于HTS-FC...针对电网故障下的双馈风力发电机组(Doubly-Fed Induction Generations,DFIG)的低电压穿越问题,提出装设电阻型高温超导故障限流器(High Temperature Superconducting Fault Current limiter,HTS-FCL)的低电压穿越保护策略。基于HTS-FCL的电特性与温度特性,采用热电类比法建立了详细的HTS-FCL仿真模型。基于DFIG的暂态模型,推导了电网故障下的DFIG暂态响应,分析了HTS-FCL保护投入后其参数对DFIG暂态响应的影响,采用模糊优化与粒子群算法相结合的方法优化了HTS-FCL的主要参数。仿真结果表明,HTS-FCL参数优化结果有较好的适用性,所提策略能够实现电网严重故障下的DFIG低电压穿越。展开更多
Na0.44MnO2 nanorods have been prepared by a hydrothermal method.The experimental parameters have been systematically investigated and optimized.The results show that Na0.44MnO2 nanorods obtained via the hydrothermal t...Na0.44MnO2 nanorods have been prepared by a hydrothermal method.The experimental parameters have been systematically investigated and optimized.The results show that Na0.44MnO2 nanorods obtained via the hydrothermal treatment at 200℃for 16 h show the best electrochemical properties,which deliver the high initial discharge capacity of 110.7 mA·h/g at 50 mA/g in potential window 2.0-4.0 V.To further improve their electrochemical properties,a ball milling process with graphene has been carried out to obtain Na0.44MnO2/graphene composite.The initial discharge capacity of Na0.44MnO2/graphene composite is 106.9 mA·h/g at a current density of 50 mA/g.After 100 cycles,the residual discharge capacity is 91.8 mA·h/g and the capacity retention rate is 85.9%,which is much higher than that of pristine Na0.44MnO2 nanorods(74.7%)at the same condition.What is more,when the current density reaches 500 and 1000 mA/g,the corresponding discharge capacities of Na0.44MnO2/graphene composite are about 89 and 78 mA·h/g,respectively,indicating outstanding rate capability.展开更多
Graphene under high temperature was prepared and loaded on Ni foam.Then,cobalt tetroxide precursor was grown on Ni foam in situ by the hydrothermal method.Finally,the sample was burned at high temperature to obtain Co...Graphene under high temperature was prepared and loaded on Ni foam.Then,cobalt tetroxide precursor was grown on Ni foam in situ by the hydrothermal method.Finally,the sample was burned at high temperature to obtain Co_(3)O_(4)+graphene@Ni.The hydrothermal method used in this paper is easy to operate,with low-risk factors and environmental protection.The prepared Co_(3)O_(4)+graphene@Ni electrode exhibits superior electrochemical performance than Co_(3)O_(4)@Ni electrode.At a current density of 1 A/g,the specific capacitance of the Co_(3)O_(4)+graphene@Ni electrode calculated by a charge-discharge test is 935 F/g,which is much larger than that of Co_(3)O_(4)@Ni electrode of 340 F/g.展开更多
The temperature of proton exchange membrane fuel cell stack and the stoichiometric oxygen in cathode have relationship with the performance and life span of fuel cells closely. The thermal coefficients were taken as i...The temperature of proton exchange membrane fuel cell stack and the stoichiometric oxygen in cathode have relationship with the performance and life span of fuel cells closely. The thermal coefficients were taken as important factors affecting the temperature distribution of fuel cells and components. According to the experimental analysis, when the stoichiometric oxygen in cathode is greater than or equal to 1.8, the stack voltage loss is the least. A novel genetic algorithm was developed to identify and optimize the variables in dynamic thermal model of proton exchange membrane fuel cell stack, making the outputs of temperature model approximate to the actual temperature, and ensuring that the maximal error is less than 1 ℃. At the same time, the optimum region of stoichiometric oxygen is obtained, which is in the range of 1.8-2.2 and accords with the experimental analysis results. The simulation and experimental results show the effectiveness of the proposed algorithm.展开更多
Lanthanum titanate （La2/3 TiO3） powders were synthesized by hydrothermal method based on the reaction of TiO2, La（NO3）3 and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure, mor...Lanthanum titanate （La2/3 TiO3） powders were synthesized by hydrothermal method based on the reaction of TiO2, La（NO3）3 and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure, morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope, transmission electron microscope and impedance method. The results show that the La2/3TiO3 particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1150℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.展开更多
A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction （CTR） process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted un...A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction （CTR） process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3＋ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure（space group p I ）, isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V （vs Ei/Li^＋）, and the capacity retains 89 mA·h/g after 30 cycles.展开更多
文摘Sulfur-doped iron-cobalt tannate nanorods(S-FeCoTA)derived from metal-organic frameworks(MOFs)as electrocatalysts were synthesized via a one-step hydrothermal method.The optimized S-FeCoTA was interlaced by loose nanorods,which had many voids.The S-FeCoTA catalysts exhibited excellent electrochemical oxygen evolution reaction(OER)performance with a low overpotential of 273 mV at 10 mA·cm^(-2)and a small Tafel slope of 36 mV·dec^(-1)in 1 mol·L^(-1)KOH.The potential remained at 1.48 V(vs RHE)at 10 mA·cm^(-2)under continuous testing for 15 h,implying that S-FeCoTA had good stability.The Faraday efficiency of S-FeCoTA was 94%.The outstanding OER activity of S-FeCoTA is attributed to the synergistic effects among S,Fe,and Co,thus promoting electron transfer,reducing the reaction kinetic barrier,and enhancing the OER performance.
基金Project(52374407)supported by the National Natural Science Foundation of China。
文摘Sulfide solid electrolytes(S-SEs)are widely preferred for their high ionic conductivity and processability.However,the further development of S-SEs is hindered by the excessive price of its critical raw materials of Li_(2)S.Herein,a low-cost and environmentally friendly method is proposed to synthesize Li_(2)S by the carbothermal reduction reaction of Li_(2)SO_(4)in one step,and the effects of various factors are also discussed.As a result,a purity of 99.67%is obtained over the self-prepared Li_(2)S.More importantly,the cost of the self-prepared Li_(2)S is only about 50$/kg,which is significantly lower than that of the commercial counterpart(10000−15000 dollar/kg).Moreover,the ionic conductivity of Li_(5.5)PS_(4.5)Cl_(1.5)prepared using self-prepared Li_(2)S as raw materials is 4.19 mS/cm at room temperature,which is a little higher than that of Li_(5.5)PS_(4.5)Cl_(1.5)using commercial Li_(2)S(4.05 mS/cm).And the all-solid-state lithium batteries(ASSLBs)with the as-prepared electrolytes could maintain a discharge capacity of 109.9 mA·h/g with an average coulombic efficiency(CE)of 98%after 100 cycles at 0.2 C,which is equivalent to that using commercial Li_(2)S,demonstrating that the preparation strategy of Li_(2)S proposed in this work is feasible.
文摘针对电网故障下的双馈风力发电机组(Doubly-Fed Induction Generations,DFIG)的低电压穿越问题,提出装设电阻型高温超导故障限流器(High Temperature Superconducting Fault Current limiter,HTS-FCL)的低电压穿越保护策略。基于HTS-FCL的电特性与温度特性,采用热电类比法建立了详细的HTS-FCL仿真模型。基于DFIG的暂态模型,推导了电网故障下的DFIG暂态响应,分析了HTS-FCL保护投入后其参数对DFIG暂态响应的影响,采用模糊优化与粒子群算法相结合的方法优化了HTS-FCL的主要参数。仿真结果表明,HTS-FCL参数优化结果有较好的适用性,所提策略能够实现电网严重故障下的DFIG低电压穿越。
基金Project(51672234)supported by the National Natural Science Foundation of ChinaProject(1337304)supported by the Program for Innovative Research Cultivation Team in University,Ministry of Education,China
文摘Na0.44MnO2 nanorods have been prepared by a hydrothermal method.The experimental parameters have been systematically investigated and optimized.The results show that Na0.44MnO2 nanorods obtained via the hydrothermal treatment at 200℃for 16 h show the best electrochemical properties,which deliver the high initial discharge capacity of 110.7 mA·h/g at 50 mA/g in potential window 2.0-4.0 V.To further improve their electrochemical properties,a ball milling process with graphene has been carried out to obtain Na0.44MnO2/graphene composite.The initial discharge capacity of Na0.44MnO2/graphene composite is 106.9 mA·h/g at a current density of 50 mA/g.After 100 cycles,the residual discharge capacity is 91.8 mA·h/g and the capacity retention rate is 85.9%,which is much higher than that of pristine Na0.44MnO2 nanorods(74.7%)at the same condition.What is more,when the current density reaches 500 and 1000 mA/g,the corresponding discharge capacities of Na0.44MnO2/graphene composite are about 89 and 78 mA·h/g,respectively,indicating outstanding rate capability.
基金Project(21502014)supported by the National Natural Science Foundation of ChinaProjects(20180550736,2019-ZD 0117)supported by the Natural Science Foundation of Liaoning Province,China+1 种基金Projects(JDL 2019004,JDL 2017027)supported by the Research Foundation of Educational Committee of Liaoning Province,ChinaProject(191008-K)supported by Guangxi Key Laboratory of Information Materials(Guilin University of Electronic Technology),China。
文摘Graphene under high temperature was prepared and loaded on Ni foam.Then,cobalt tetroxide precursor was grown on Ni foam in situ by the hydrothermal method.Finally,the sample was burned at high temperature to obtain Co_(3)O_(4)+graphene@Ni.The hydrothermal method used in this paper is easy to operate,with low-risk factors and environmental protection.The prepared Co_(3)O_(4)+graphene@Ni electrode exhibits superior electrochemical performance than Co_(3)O_(4)@Ni electrode.At a current density of 1 A/g,the specific capacitance of the Co_(3)O_(4)+graphene@Ni electrode calculated by a charge-discharge test is 935 F/g,which is much larger than that of Co_(3)O_(4)@Ni electrode of 340 F/g.
基金Project (2003AA517020) supported by the National High-Technology Research Plan of China
文摘The temperature of proton exchange membrane fuel cell stack and the stoichiometric oxygen in cathode have relationship with the performance and life span of fuel cells closely. The thermal coefficients were taken as important factors affecting the temperature distribution of fuel cells and components. According to the experimental analysis, when the stoichiometric oxygen in cathode is greater than or equal to 1.8, the stack voltage loss is the least. A novel genetic algorithm was developed to identify and optimize the variables in dynamic thermal model of proton exchange membrane fuel cell stack, making the outputs of temperature model approximate to the actual temperature, and ensuring that the maximal error is less than 1 ℃. At the same time, the optimum region of stoichiometric oxygen is obtained, which is in the range of 1.8-2.2 and accords with the experimental analysis results. The simulation and experimental results show the effectiveness of the proposed algorithm.
文摘Lanthanum titanate （La2/3 TiO3） powders were synthesized by hydrothermal method based on the reaction of TiO2, La（NO3）3 and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure, morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope, transmission electron microscope and impedance method. The results show that the La2/3TiO3 particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1150℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.
基金Project(50302016) supported by the National Natural Science Foundation of China
文摘A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction （CTR） process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3＋ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure（space group p I ）, isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V （vs Ei/Li^＋）, and the capacity retains 89 mA·h/g after 30 cycles.
