锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的...锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的T-Nb_2O_5/AC锂离子混合电容器。循环伏安和恒电流充放电的测试结果表明该锂离子混合电容器具有较好的电化学性能,如在碳酸酯类的有机电解液中,工作电压可达到3.0 V;在100 m A·g^(-1)的电流密度下,电容器的比能量和比功率密度可达到53.79 Wh·kg^(-1)和294 W·kg^(-1);在200 m A·g^(-1)的电流密度下,经过1000次充放电循环后,该电容器的比能量保持率为73%。由此可见,本工作开发的T-Nb_2O_5/AC锂离子混合电容器将在高功率的储能设备中有很好地应用前景。展开更多
【目的】为研究混合锂离子超级电容器(hybrid lithium ion supercapacitor,HLIC)的性能,分析多种干扰因素对其电化学与热特性的影响。【方法】首先建立HLIC电化学热耦合模型;其次通过试验与数值模拟相互验证来证明模型的可靠性;最后分...【目的】为研究混合锂离子超级电容器(hybrid lithium ion supercapacitor,HLIC)的性能,分析多种干扰因素对其电化学与热特性的影响。【方法】首先建立HLIC电化学热耦合模型;其次通过试验与数值模拟相互验证来证明模型的可靠性;最后分析阳极活性材料颗粒粒径、充放电倍率、电芯结构状态对HLIC的电化学与热特性的影响,并通过建立核壳模型绘制核壳图,从微观的角度分析了阳极活性材料颗粒粒径对HLIC电化学性能的影响过程。【结果】HLIC在高倍率的条件下,减小粒径可使阳极活性材料颗粒锂化程度显著提高,10 C倍率下粒径15.5μm与0.5μm的单体相比,前者能量密度降低了63.14%,平均发热率增加了121.66%,最大温度上升了17.7 K;而在低倍率的条件下,粒径对HLIC的性能影响不大,无须增加成本过分减小粒径,并且电芯在层压方向导热性较差,需要在层压方向上增加散热以保证其工作性能良好。【结论】本研究对各个场景所需的HLIC性能参数的选取具有一定的参考意义。展开更多
An electrical equivalent circuit model for lithium-ion batteries used for hybrid electric vehicles （HEV） is presented. The model has two RC networks characterizing battery activation and concentration polarization p...An electrical equivalent circuit model for lithium-ion batteries used for hybrid electric vehicles （HEV） is presented. The model has two RC networks characterizing battery activation and concentration polarization process. The parameters of the model are identified using combined experimental and extended Kalman filter （EKF） recursive methods. The open-circuit voltage and ohmic resistance of the battery are directly measured and calculated from experimental measurements, respectively. The rest of the coupled dynamic parameters, i.e. the RC network parameters, are estimated using the EKF method. Experimental and simulation results are presented to demonstrate the efficacy of the proposed circuit model and parameter identification techniques for simulating battery dynamics.展开更多
This paper reports the results of investigating the permissible amount of battery deterioration. An investigation was carried out using the following two types of vehicles： a BEV （battery electric vehicle） and a H...This paper reports the results of investigating the permissible amount of battery deterioration. An investigation was carried out using the following two types of vehicles： a BEV （battery electric vehicle） and a HEV （hybrid electric vehicle）. First, a detailed evaluation was carried out to identify how the vehicle performance was adversely affected as the lithium-ion batteries installed in the vehicles deteriorated. Next, an attempt was made to determine the permissible amount of deterioration for the vehicle-mounted lithium-ion batteries. In the case of the BEV, the driving distance declined by 20% when the capacity maintenance rate was approximately 80%. Therefore, this was specified as the permissible amount of battery deterioration for the BEV. In the case of the HEV, the fuel consumption increased by 20% when the maximum battery output maintenance rate was approximately 40%. Therefore, this was specified as the permissible amount of battery deterioration for the HEV.展开更多
We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion ba...We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion batteries, the uniformly deposited amorphous silicon （a-Si） works as the active material to store electrical energy, and the pre-coated carbon nanofibers （CNFs） serve as both the electron conducting pathway and a strain/stress relaxation layer for the sputtered a-Si layers during the intercalation process of lithium ions. As a result, the as-fabricated lithium ion batteries, with deposited a-Si thicknesses of 200 nm or 300 nm, not only exhibit a high specific capacity of 〉2000 mA.h/g, but also show a good capacity retention of over 80% and Coulombic efficiency of 〉98% after a large number of charge/discharge experiments. Our approach offers an efficient and scalable method to obtain silicon-carbon nanostructured composites for application in lithium ion batteries.展开更多
TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highr...TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highrate capability is limited by their poor electronic and ionic conductivity.In particular,studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported.Herein,a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported.This binder-free TNO anode exhibits superior rate performance(~66.3%capacity retention as the rate increases from 1 to 40 C),which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods,facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network.Furthermore,the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility(no capacity loss after continuous bending for 500 times).Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 mW h cm^-3/419.3 mW cm^-3),more superior to previously reported hybrid supercapacitors.The device also efficiently powers an LED light upon 180°bending.展开更多
There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors wi...There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 （LTO） composite anode （G-LTO） and a three-dimensional porous graphene-sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries （energy source） and supercapacitors （power source）. Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA-h.g-1 for pure LTO, the G-LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·1h·g-1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0-2.5 V vs. Li/Li＋; these are among the highest values for LTO-based nano- composites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg-1 at a rate of 0.4 C （2.5 h） over a wide voltage range （0-3 V）, and still retained an energy density of 32 Wh·kg-1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.展开更多
Cobalt oxides, such as C0304 and CoO, have received increasing attention as potential anode materials for rechargeable lithium-ion batteries （LIBs） owing to their high theoretical capacity. Nanostructure engineering...Cobalt oxides, such as C0304 and CoO, have received increasing attention as potential anode materials for rechargeable lithium-ion batteries （LIBs） owing to their high theoretical capacity. Nanostructure engineering has been demonstrated as an effective approach to improve the electrochemical performance of electrode materials for LIBs. In this review, we summarize recent developments in the rational design and fabrication of various cobalt oxide-based nanomaterials and their lithium storage performance, including 1D nanowires/belts, 2D nanosheets, 3D hollow/hierarchical structures, hybrid nanostructures with carbon （amorphous carbon, carbon nanotubes and graphene） and mixed metal oxides. By focusing on the effects of their structure on their electrochemical performance, effective strategies for the fabrication of cobalt oxide/carbon hybrid nanostructures are highlighted. This review shows that by rational design, such cobalt-oxide-based nanornaterials are very promising as next generation LIB anodes.展开更多
文摘锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的T-Nb_2O_5/AC锂离子混合电容器。循环伏安和恒电流充放电的测试结果表明该锂离子混合电容器具有较好的电化学性能,如在碳酸酯类的有机电解液中,工作电压可达到3.0 V;在100 m A·g^(-1)的电流密度下,电容器的比能量和比功率密度可达到53.79 Wh·kg^(-1)和294 W·kg^(-1);在200 m A·g^(-1)的电流密度下,经过1000次充放电循环后,该电容器的比能量保持率为73%。由此可见,本工作开发的T-Nb_2O_5/AC锂离子混合电容器将在高功率的储能设备中有很好地应用前景。
文摘An electrical equivalent circuit model for lithium-ion batteries used for hybrid electric vehicles （HEV） is presented. The model has two RC networks characterizing battery activation and concentration polarization process. The parameters of the model are identified using combined experimental and extended Kalman filter （EKF） recursive methods. The open-circuit voltage and ohmic resistance of the battery are directly measured and calculated from experimental measurements, respectively. The rest of the coupled dynamic parameters, i.e. the RC network parameters, are estimated using the EKF method. Experimental and simulation results are presented to demonstrate the efficacy of the proposed circuit model and parameter identification techniques for simulating battery dynamics.
文摘This paper reports the results of investigating the permissible amount of battery deterioration. An investigation was carried out using the following two types of vehicles： a BEV （battery electric vehicle） and a HEV （hybrid electric vehicle）. First, a detailed evaluation was carried out to identify how the vehicle performance was adversely affected as the lithium-ion batteries installed in the vehicles deteriorated. Next, an attempt was made to determine the permissible amount of deterioration for the vehicle-mounted lithium-ion batteries. In the case of the BEV, the driving distance declined by 20% when the capacity maintenance rate was approximately 80%. Therefore, this was specified as the permissible amount of battery deterioration for the BEV. In the case of the HEV, the fuel consumption increased by 20% when the maximum battery output maintenance rate was approximately 40%. Therefore, this was specified as the permissible amount of battery deterioration for the HEV.
基金We acknowledge financial support from the National Science Foundation （CCF 0726815 and CCF 0702204）.
文摘We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion batteries, the uniformly deposited amorphous silicon （a-Si） works as the active material to store electrical energy, and the pre-coated carbon nanofibers （CNFs） serve as both the electron conducting pathway and a strain/stress relaxation layer for the sputtered a-Si layers during the intercalation process of lithium ions. As a result, the as-fabricated lithium ion batteries, with deposited a-Si thicknesses of 200 nm or 300 nm, not only exhibit a high specific capacity of 〉2000 mA.h/g, but also show a good capacity retention of over 80% and Coulombic efficiency of 〉98% after a large number of charge/discharge experiments. Our approach offers an efficient and scalable method to obtain silicon-carbon nanostructured composites for application in lithium ion batteries.
基金supported by the National Natural Science Foundation of China (51672205, 21673169 and 51972257)the National Key R&D Program of China (2016YFA0202602)the Natural Science Foundation of Hubei Province (2018CFB581)
文摘TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highrate capability is limited by their poor electronic and ionic conductivity.In particular,studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported.Herein,a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported.This binder-free TNO anode exhibits superior rate performance(~66.3%capacity retention as the rate increases from 1 to 40 C),which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods,facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network.Furthermore,the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility(no capacity loss after continuous bending for 500 times).Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 mW h cm^-3/419.3 mW cm^-3),more superior to previously reported hybrid supercapacitors.The device also efficiently powers an LED light upon 180°bending.
基金The authors gratefully acknowledge financial support from Ministry of Science and Technology of the People＇s Republic of China （MOST） （Grants Nos. 2012CB933401 and 2011DFB50300）, and National Natural Science Foundation of China （NSFC） （Grants Nos. 50933003 and 51273093）.
文摘There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 （LTO） composite anode （G-LTO） and a three-dimensional porous graphene-sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries （energy source） and supercapacitors （power source）. Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA-h.g-1 for pure LTO, the G-LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·1h·g-1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0-2.5 V vs. Li/Li＋; these are among the highest values for LTO-based nano- composites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg-1 at a rate of 0.4 C （2.5 h） over a wide voltage range （0-3 V）, and still retained an energy density of 32 Wh·kg-1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.
文摘Cobalt oxides, such as C0304 and CoO, have received increasing attention as potential anode materials for rechargeable lithium-ion batteries （LIBs） owing to their high theoretical capacity. Nanostructure engineering has been demonstrated as an effective approach to improve the electrochemical performance of electrode materials for LIBs. In this review, we summarize recent developments in the rational design and fabrication of various cobalt oxide-based nanomaterials and their lithium storage performance, including 1D nanowires/belts, 2D nanosheets, 3D hollow/hierarchical structures, hybrid nanostructures with carbon （amorphous carbon, carbon nanotubes and graphene） and mixed metal oxides. By focusing on the effects of their structure on their electrochemical performance, effective strategies for the fabrication of cobalt oxide/carbon hybrid nanostructures are highlighted. This review shows that by rational design, such cobalt-oxide-based nanornaterials are very promising as next generation LIB anodes.
