Mechanical degradation, especially fractures in active particles in an electrode, is a major reason why the capacity of lithiumion batteries fades. This paper proposes a model that couples Li-ion diffusion, stress evo...Mechanical degradation, especially fractures in active particles in an electrode, is a major reason why the capacity of lithiumion batteries fades. This paper proposes a model that couples Li-ion diffusion, stress evolution, and damage mechanics to simulate the growth of central cracks in cathode particles(Li Mn_2 O_4) by an extended finite element method by considering the influence of multiple factors. The simulation shows that particles are likely to crack at a high discharge rate, when the particle radius is large, or when the initial central crack is longer. It also shows that the maximum principal tensile stress decreases and cracking becomes more difficult when the influence of crack surface diffusion is considered. The fracturing process occurs according to the following stages: no crack growth, stable crack growth, and unstable crack growth. Changing the charge/discharge strategy before unstable crack growth sets in is beneficial to prevent further capacity fading during electrochemical cycling.展开更多
In this paper,the functional polymeric active materials were prepared by the grafting copolymerization and their structure and properties were studied.The results show that the structure and properties of these ac- ti...In this paper,the functional polymeric active materials were prepared by the grafting copolymerization and their structure and properties were studied.The results show that the structure and properties of these ac- tive materials have the relative large effects on the properties of gadolinium ion selective electrodes.展开更多
The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studie...The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.展开更多
A Ag|AgCl reference electrode which can be used in molten carbonate media has been described in this paper.It consists of a silver wire immersed in a solution of AgCl(1mol%) in (Li 0.62 ,K 0.38 ) 2CO 3,with ...A Ag|AgCl reference electrode which can be used in molten carbonate media has been described in this paper.It consists of a silver wire immersed in a solution of AgCl(1mol%) in (Li 0.62 ,K 0.38 ) 2CO 3,with a zirconia junction.The main properties of reference electrode,such as reproducibility ,stability and reversibility, were checked.The results have demonstrated that the reference electrode is reliable.With such reference electrode catalysis of various electrode materials to oxygen reduction in molten alkali carbonate media was investigated.It is found that as catalysts for oxygen reduction oxidized nickel niobium alloy is superior to nickel oxide.展开更多
Sodium-ion capacitors(NICs)trigger considerable attention due to their higher specific energy than electrical double-layer capacitors(EDLCs)at comparable specific power.However,the presodiation process of the anodic h...Sodium-ion capacitors(NICs)trigger considerable attention due to their higher specific energy than electrical double-layer capacitors(EDLCs)at comparable specific power.However,the presodiation process of the anodic host is extremely crucial for the construction of high-performance NICs.Herein,a positive EDL electrode containing activated carbon(AC)mixed with sodium cyanide(NaCN)as a sacrificial material was electrochemically oxidized to presodiate a Sn_(4)P_(3) anodic host buffered by hard carbon(HC).The oxidation of CN-occurred ca.2.9 V vs.Na/Na+and finished by a short region of linearly increasing potential with a total capacity close to the theoretical value of 547 mAh g^(-1).The operando electrochemical mass spectrometry(EMS)analysis of the atmosphere in the cell together with the internal pressure measurements realized during the galvanostatic oxidation of a YP80F-NaCN electrode demonstrate that the process occurs without any gas evolution.A precursor cell of an NIC was constructed in a pouch with YP80FNaCN and HC/Sn_(4)P_(3) electrodes.After the oxidative sodium transfer from NaCN to HC/Sn_(4)P_(3),the realized YP80F//Nax(HC/Sn_(4)P_(3))NIC demonstrated a discharge capacitance retention higher than 80%for 8900 cycles in the voltage range from 2.0 to 3.8 V.The infrared analysis of the anode obtained by the herein described transfer process detected polycyanogen,which stabilizes the electrode structure during cycling,and thereof is at the origin of the enhanced life span of the NIC.展开更多
The effect of smelting processes on mechanical properties and microstructure of reduced activation ferritic steels was studied.Creep properties and impact toughness of reduced activation ferritic steels were obviously...The effect of smelting processes on mechanical properties and microstructure of reduced activation ferritic steels was studied.Creep properties and impact toughness of reduced activation ferritic steels were obviously improved by vacuum induction melting followed by consumable electrode remelting process in comparison with the conventional vacuum induction melting process.The difference of impact toughness and creep properties between both steels mainly depended on the aspect ratio and mean size of precipitates.Decreasing the aspect ratio of carbides makes development of a shear band more difficult , which could increase impact energy and creep resistance.展开更多
Nanowire-shaped α-Mo O3 was synthesized on a large scale by hydrothermal route.Nanocrystalline α-Mo2 C phase was obtained by the carburization of α-Mo O3 nanowires with urea as a carbon source precursor.The phase p...Nanowire-shaped α-Mo O3 was synthesized on a large scale by hydrothermal route.Nanocrystalline α-Mo2 C phase was obtained by the carburization of α-Mo O3 nanowires with urea as a carbon source precursor.The phase purity and crystalline size of the synthesized materials were ascertained by using powder X-ray diffraction.The shape and morphology of synthesized materials were characterized by field-emission scanning electron microscopy(FE-SEM) and high resolution transmission electron microscopy(HR-TEM).The electrocatalytic activity of α-Mo2 C for I-/I3^-redox couple was investigated by the cyclic voltammetry.The synthesized α-Mo2 C was subsequently applied as counter electrode in dye-sensitized solar cells to replace the expensive platinum.展开更多
基金support of the National Natural Science Foundation of China (11472165 and 11332005)
文摘Mechanical degradation, especially fractures in active particles in an electrode, is a major reason why the capacity of lithiumion batteries fades. This paper proposes a model that couples Li-ion diffusion, stress evolution, and damage mechanics to simulate the growth of central cracks in cathode particles(Li Mn_2 O_4) by an extended finite element method by considering the influence of multiple factors. The simulation shows that particles are likely to crack at a high discharge rate, when the particle radius is large, or when the initial central crack is longer. It also shows that the maximum principal tensile stress decreases and cracking becomes more difficult when the influence of crack surface diffusion is considered. The fracturing process occurs according to the following stages: no crack growth, stable crack growth, and unstable crack growth. Changing the charge/discharge strategy before unstable crack growth sets in is beneficial to prevent further capacity fading during electrochemical cycling.
文摘In this paper,the functional polymeric active materials were prepared by the grafting copolymerization and their structure and properties were studied.The results show that the structure and properties of these ac- tive materials have the relative large effects on the properties of gadolinium ion selective electrodes.
文摘The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.
文摘A Ag|AgCl reference electrode which can be used in molten carbonate media has been described in this paper.It consists of a silver wire immersed in a solution of AgCl(1mol%) in (Li 0.62 ,K 0.38 ) 2CO 3,with a zirconia junction.The main properties of reference electrode,such as reproducibility ,stability and reversibility, were checked.The results have demonstrated that the reference electrode is reliable.With such reference electrode catalysis of various electrode materials to oxygen reduction in molten alkali carbonate media was investigated.It is found that as catalysts for oxygen reduction oxidized nickel niobium alloy is superior to nickel oxide.
基金the Foundation for Polish Science(FNP)for funding the HYCAP project(research grant TEAM TECH/POIR.04.04.00-00-3D6F/16-00)carried out within the TEAM TECH program co-financed by the European Union under the European Regional Development Fund。
文摘Sodium-ion capacitors(NICs)trigger considerable attention due to their higher specific energy than electrical double-layer capacitors(EDLCs)at comparable specific power.However,the presodiation process of the anodic host is extremely crucial for the construction of high-performance NICs.Herein,a positive EDL electrode containing activated carbon(AC)mixed with sodium cyanide(NaCN)as a sacrificial material was electrochemically oxidized to presodiate a Sn_(4)P_(3) anodic host buffered by hard carbon(HC).The oxidation of CN-occurred ca.2.9 V vs.Na/Na+and finished by a short region of linearly increasing potential with a total capacity close to the theoretical value of 547 mAh g^(-1).The operando electrochemical mass spectrometry(EMS)analysis of the atmosphere in the cell together with the internal pressure measurements realized during the galvanostatic oxidation of a YP80F-NaCN electrode demonstrate that the process occurs without any gas evolution.A precursor cell of an NIC was constructed in a pouch with YP80FNaCN and HC/Sn_(4)P_(3) electrodes.After the oxidative sodium transfer from NaCN to HC/Sn_(4)P_(3),the realized YP80F//Nax(HC/Sn_(4)P_(3))NIC demonstrated a discharge capacitance retention higher than 80%for 8900 cycles in the voltage range from 2.0 to 3.8 V.The infrared analysis of the anode obtained by the herein described transfer process detected polycyanogen,which stabilizes the electrode structure during cycling,and thereof is at the origin of the enhanced life span of the NIC.
基金Item Sponsored by National Basic Research Program of China ( 2011GB108006 )National Natural Science Foundation of China ( 51071090 )
文摘The effect of smelting processes on mechanical properties and microstructure of reduced activation ferritic steels was studied.Creep properties and impact toughness of reduced activation ferritic steels were obviously improved by vacuum induction melting followed by consumable electrode remelting process in comparison with the conventional vacuum induction melting process.The difference of impact toughness and creep properties between both steels mainly depended on the aspect ratio and mean size of precipitates.Decreasing the aspect ratio of carbides makes development of a shear band more difficult , which could increase impact energy and creep resistance.
基金the financial support from the Department of Atomic Energy–Board of Research in Nuclear Sciences(DAE-BRNS)(Grant No.2013/37P/1/BRNS),Mumbai,India
文摘Nanowire-shaped α-Mo O3 was synthesized on a large scale by hydrothermal route.Nanocrystalline α-Mo2 C phase was obtained by the carburization of α-Mo O3 nanowires with urea as a carbon source precursor.The phase purity and crystalline size of the synthesized materials were ascertained by using powder X-ray diffraction.The shape and morphology of synthesized materials were characterized by field-emission scanning electron microscopy(FE-SEM) and high resolution transmission electron microscopy(HR-TEM).The electrocatalytic activity of α-Mo2 C for I-/I3^-redox couple was investigated by the cyclic voltammetry.The synthesized α-Mo2 C was subsequently applied as counter electrode in dye-sensitized solar cells to replace the expensive platinum.