Machine learning-based methods have emerged as a promising solution to accurate battery capacity estimation for battery management systems.However,they are generally developed in a supervised manner which requires a c...Machine learning-based methods have emerged as a promising solution to accurate battery capacity estimation for battery management systems.However,they are generally developed in a supervised manner which requires a considerable number of input features and corresponding capacities,leading to prohibitive costs and efforts for data collection.In response to this issue,this study proposes a convolutional neural network(CNN)based method to perform end-to-end capacity estimation by taking only raw impedance spectra as input.More importantly,an input reconstruction module is devised to effectively exploit impedance spectra without corresponding capacities in the training process,thereby significantly alleviating the cost of collecting training data.Two large battery degradation datasets encompassing over 4700 impedance spectra are developed to validate the proposed method.The results show that accurate capacity estimation can be achieved when substantial training samples with measured capacities are given.However,the estimation performance of supervised machine learning algorithms sharply deteriorates when fewer samples with measured capacities are available.In this case,the proposed method outperforms supervised benchmarks and can reduce the root mean square error by up to 50.66%.A further validation under different current rates and states of charge confirms the effectiveness of the proposed method.Our method provides a flexible approach to take advantage of unlabelled samples for developing data-driven models and is promising to be generalised to other battery management tasks.展开更多
The lithium-ion battery has been widely used as an energy source. Charge rate, discharge rate, and operating tem- perature are very important factors for the capacity degradations of power batteries and battery packs....The lithium-ion battery has been widely used as an energy source. Charge rate, discharge rate, and operating tem- perature are very important factors for the capacity degradations of power batteries and battery packs. Firstly, in this paper we make use of an accelerated life test and a statistical analysis method to establish the capacity accelerated degradation model under three constant stress parameters according to the degradation data, which are charge rate, discharge rate, and operating temperature, and then we propose a capacity degradation model according to the current residual capacity of a Li-ion cell under dynamic stress parameters. Secondly, we analyze the charge and discharge process of a series power battery pack and interpret the correlation between the capacity degradations of the battery pack and its charge/discharge rate. According to this cycling condition, we establish a capacity degradation model of a series power battery pack under inconsistent capacity of cells, and analyze the degradation mechanism with capacity variance and operating temperature difference. The comparative analysis of test results shows that the inconsistent operating temperatures of cells in the series power battery pack are the main cause of its degradation; when the difference between inconsistent temperatures is narrowed by 5 ℃, the cycle life can be improved by more than 50%. Therefore, it effectively improves the cycle life of the series battery pack to reasonably assemble the batteries according to their capacities and to narrow the differences in operating temperature among cells.展开更多
Analyzing capacity degradation characteristics and accurately predicting the knee point of capacity are crucial for the safety management of lithium-ion batteries(LIBs).However,the degradation mechanism of LIBs is com...Analyzing capacity degradation characteristics and accurately predicting the knee point of capacity are crucial for the safety management of lithium-ion batteries(LIBs).However,the degradation mechanism of LIBs is complex.A key but challenging problem is how to clarify the degradation mechanism and predict the knee point.According to the external characteristics such as capacity decline gradievnt and the peak value of increment capacity curve(IC curve),the capacity degradation can be divided into four stages,including initial decline stage,slow decline stage,transition stage and high-speed decline stage.The degradation mechanism of LIBs is compared from the longitudinal and horizontal aspects,respectively.Among them,the battery usage from the initial stage to the end of life(EOL)is longitudinal analysis.The battery under different conditions,such as charging and discharging,different discharge rate,different cathode material degradation mechanism is horizontal analysis.Moreover,a method based on neural network is proposed to predict the knee point.Two features are used to predict the capacity and cycle of the knee point,which are the gradient of the capacity degradation curve and the difference of the IC curve with the maximum correlation.The experimental results show that a two-dimensional surface can be obtained using only the first 100 cycles,which can provide a reference for the position of the knee point accurately prediction.展开更多
The ever-increasing future demands of electrification and grid storage have spurred continued research to develop rechargeable battery chemistries for reliable energy storage[1].Beyond current lithium-ion batteries,li...The ever-increasing future demands of electrification and grid storage have spurred continued research to develop rechargeable battery chemistries for reliable energy storage[1].Beyond current lithium-ion batteries,lithium–sulfur battery represents a promising system due to its high energy density(2600 Wh kg^(-1))and low material cost[2].展开更多
In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles a...In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles are studied by soft x-ray absorption spectroscopy in total electron（TEY） and fluorescence（TFY） detection modes, which provide surface and bulk information, respectively. The spectra of Co L2,3-edge indicate that Co contributes to charge compensation below 4.4 V.Combining with the spectra of O K-edge, it manifests that only O contributes to electron compensation above 4.4 V with the formation of local O 2 p holes both on the surface and in the bulk, where the surficial O evolves more remarkably. The evolution of the O 2 p holes gives an explanation to the origin of O2^-or even O2. A comparison between the TEY and TFY of O K-edge spectra of LiCoO2 cycled in a range from 3 V to 4.6 V indicates both the structural change in the bulk and aggregation of lithium salts on the electrode surface are responsible for the capacity fading. However, the latter is found to play a more important role after many cycles.展开更多
The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the...The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF（1,3,5-Triphenylformazan） amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP （pentachlorophenol） removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.展开更多
The La-Mg-Ni-Mn-based AB_2-type La_（1-x）Ce_xMgNi_（3.5）Mn_（0.5）（x = 0, 0.1, 0.2, 0.3, and 0.4） alloys were fabricated by melt spinning technology. The effects of Ce content on the structures and electrochemical...The La-Mg-Ni-Mn-based AB_2-type La_（1-x）Ce_xMgNi_（3.5）Mn_（0.5）（x = 0, 0.1, 0.2, 0.3, and 0.4） alloys were fabricated by melt spinning technology. The effects of Ce content on the structures and electrochemical hydrogen storage performances of the alloys were studied systematically. The XRD and SEM analyses proved that the experimental alloys consist of a major phase LaMgNi_4 and a secondary phase LaNi_5. The variation of Ce content causes an obvious change in the phase abundance of the alloys without changing the phase composition. Namely, with the increase of Ce content, the LaMgNi_4 phase augments and the LaNi_5 phase declines. The lattice constants and cell volumes of the alloys clearly shrink with increasing Ce content. Moreover, the Ce substitution for La results in the grains of the alloys clearly refined. The electrochemical tests showed that the substitution of Ce for La obviously improves the cycle stability of the as-spun alloys. The analyses on the capacity degradation mechanism demonstrate that the improvement can be attributed to the ameliorated anti-corrosion and antioxidation ability originating from substituting partial La with Ce. The as-spun alloys exhibit excellent activation capability, reaching the maximum discharge capacities just at the first cycling without any activation treatment. The substitution of Ce for La evidently improves the discharge potential characteristics of the as-spun alloys. The discharge capacity of the alloys first increases and then decreases with growing Ce content. Furthermore, a similar trend also exists in the electrochemical kinetics of the alloys, including the high rate discharge ability（HRD）, hydrogen diffusion coefficient（D）, limiting current density（IL） and charge transfer rate.展开更多
Nickel-rich layered oxides have been identified as the most promising commercial cathode materials for lithium-ion batteries(LIBs)for their high theoretical specific capacity.However,the poor cycling stability of nick...Nickel-rich layered oxides have been identified as the most promising commercial cathode materials for lithium-ion batteries(LIBs)for their high theoretical specific capacity.However,the poor cycling stability of nickel-rich cathode materials is one of the major barriers for the large-scale usage of LIBs.The existing obstructions that suppress the capacity degradation of nickel-rich cathode materials are as a result of phase transition,mechanical instability,intergranular cracks,side reaction,oxygen loss,and thermal instability during cycling.Core–shell structures,oxidating precursors,electrolyte additives,doping/coating and synthesizing single crystals have been identified as effective methods to improve cycling stability of nickel-rich cathode materials.Herein,recent progress of surface modification,e.g.coating and doping,in nickel-rich cathode materials are summarized based on Periodic table to provide a clear understanding.Electrochemical performances and mechanisms of modified structure are discussed in detail.It is hoped that an overview of synthesis and surface modification can be presented and a perspective of nickel-rich materials in LIBs can be given.展开更多
A model is proposed to describe the passengers’route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand,sensitive and insensitive passenger.The inse...A model is proposed to describe the passengers’route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand,sensitive and insensitive passenger.The insensitive passengers choose their route without paying much attention to congestion.To the contrary,sensitive passengers who consider route congestion choose travel route based on generalized cost.An equilibrium state is given by variational inequalities in terms of travel generalized cost,which is represented by the combinations of mean and variance of total travel time.The diagonalization algorithm is given to solve this programming.Results show that insensitive passengers have large effects on the path choice than sensitive ones,especially for the larger demand.展开更多
Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge...Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge/discharge process of commercial lithium-ion batteries of mobile telephone, degradation analysis and related mechanisms are put forward and discussed in the paper. The impedance spectra of prismatic commercial lithium-ion batteries are measured at various state of charge after different charge/discharge cycles. The incastared impedance spectra are discussed with a proposed equivalent circuit. Results indicated that the structure change of electrode materials or swell and shrink of crystal lattice, decompose of electrolyte, dissolution of active materials and solid electrolyte interphase film formation are the main reasons leading to the capacity degradation.展开更多
There is a large demand for models able to predict the future capacity retention and internal resistance(IR)of Lithium-ion battery cells with as little testing as possible.We provide a data-centric model accurately pr...There is a large demand for models able to predict the future capacity retention and internal resistance(IR)of Lithium-ion battery cells with as little testing as possible.We provide a data-centric model accurately predicting a cell’s entire capacity and IR trajectory from one single cycle of input data.This represents a significant reduction in the amount of input data needed over previous works.Our approach characterises the capacity and IR curve through a small number of key points,which,once predicted and interpolated,describe the full curve.With this approach the remaining useful life is predicted with an 8.6%mean absolute percentage error when the input-cycle is within the first 100 cycles.展开更多
In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were inves...In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were investigated in detail.The structural analysis identifies that（La,Mg）Ni3（PuNi3-type） phase transforms to amorphous,i.e.,hydrogen-induced amorphization（HIA） occurs whereas LaNi5（CaCu5-type）,（La,Mg）2Ni7（Ce2Ni7-type）,and（La,Mg）5Ni19（Pr5Co19-type） phases still keep crystalline upon hydriding/dehydriding cycling.Partial amorphization remarkably affects both the gas-solid and electrochemical storage performances.The plateau of PCT curves becomes narrow and steep with cycling.Moreover,the maximum electrochemical capacity decreases notably after gas-solid hydrogenation repeats.The electrochemical capacity reduction could be ascribed to both drop of the maximum storage capacity and the slope of plateau induced by partial amorphization.For direct electrochemical cycling,it is suggested that the capacity decay is mainly attributed to HIA in the initial stage.展开更多
基金supported by the National Key R&D Program of China(2021YFB2402002)the National Natural Science Foundation of China(51922006 and 51877009)+1 种基金the China Postdoctoral Science Foundation(BX2021035 and 2022M710379)the Beijing Natural Science Foundation(Grant No.L223013)。
文摘Machine learning-based methods have emerged as a promising solution to accurate battery capacity estimation for battery management systems.However,they are generally developed in a supervised manner which requires a considerable number of input features and corresponding capacities,leading to prohibitive costs and efforts for data collection.In response to this issue,this study proposes a convolutional neural network(CNN)based method to perform end-to-end capacity estimation by taking only raw impedance spectra as input.More importantly,an input reconstruction module is devised to effectively exploit impedance spectra without corresponding capacities in the training process,thereby significantly alleviating the cost of collecting training data.Two large battery degradation datasets encompassing over 4700 impedance spectra are developed to validate the proposed method.The results show that accurate capacity estimation can be achieved when substantial training samples with measured capacities are given.However,the estimation performance of supervised machine learning algorithms sharply deteriorates when fewer samples with measured capacities are available.In this case,the proposed method outperforms supervised benchmarks and can reduce the root mean square error by up to 50.66%.A further validation under different current rates and states of charge confirms the effectiveness of the proposed method.Our method provides a flexible approach to take advantage of unlabelled samples for developing data-driven models and is promising to be generalised to other battery management tasks.
基金supported by the National Natural Science Foundation of China(Grant Nos.61004092 and 51007088)the National High Technology Research and Development Program of China(Grant Nos.2011AA11A251 and 2011AA11A262)+1 种基金the International Science&Technology Cooperation Program of China(Grant Nos.2010DFA72760 and 2011DFA70570)the Research Foundation of National Engineering Laboratory for Electric Vehicles,China(GrantNo.2012-NELEV-03)
文摘The lithium-ion battery has been widely used as an energy source. Charge rate, discharge rate, and operating tem- perature are very important factors for the capacity degradations of power batteries and battery packs. Firstly, in this paper we make use of an accelerated life test and a statistical analysis method to establish the capacity accelerated degradation model under three constant stress parameters according to the degradation data, which are charge rate, discharge rate, and operating temperature, and then we propose a capacity degradation model according to the current residual capacity of a Li-ion cell under dynamic stress parameters. Secondly, we analyze the charge and discharge process of a series power battery pack and interpret the correlation between the capacity degradations of the battery pack and its charge/discharge rate. According to this cycling condition, we establish a capacity degradation model of a series power battery pack under inconsistent capacity of cells, and analyze the degradation mechanism with capacity variance and operating temperature difference. The comparative analysis of test results shows that the inconsistent operating temperatures of cells in the series power battery pack are the main cause of its degradation; when the difference between inconsistent temperatures is narrowed by 5 ℃, the cycle life can be improved by more than 50%. Therefore, it effectively improves the cycle life of the series battery pack to reasonably assemble the batteries according to their capacities and to narrow the differences in operating temperature among cells.
基金supported by the National Natural Science Foundation of China(No.62173211,62122041,62333013)the Natural Science Foundation of Shandong Province(No.ZR2021JQ25)which are gratefully acknowledged.
文摘Analyzing capacity degradation characteristics and accurately predicting the knee point of capacity are crucial for the safety management of lithium-ion batteries(LIBs).However,the degradation mechanism of LIBs is complex.A key but challenging problem is how to clarify the degradation mechanism and predict the knee point.According to the external characteristics such as capacity decline gradievnt and the peak value of increment capacity curve(IC curve),the capacity degradation can be divided into four stages,including initial decline stage,slow decline stage,transition stage and high-speed decline stage.The degradation mechanism of LIBs is compared from the longitudinal and horizontal aspects,respectively.Among them,the battery usage from the initial stage to the end of life(EOL)is longitudinal analysis.The battery under different conditions,such as charging and discharging,different discharge rate,different cathode material degradation mechanism is horizontal analysis.Moreover,a method based on neural network is proposed to predict the knee point.Two features are used to predict the capacity and cycle of the knee point,which are the gradient of the capacity degradation curve and the difference of the IC curve with the maximum correlation.The experimental results show that a two-dimensional surface can be obtained using only the first 100 cycles,which can provide a reference for the position of the knee point accurately prediction.
基金supported by the Agency for Science,Technology and Research(Central Research Fund Award)。
文摘The ever-increasing future demands of electrification and grid storage have spurred continued research to develop rechargeable battery chemistries for reliable energy storage[1].Beyond current lithium-ion batteries,lithium–sulfur battery represents a promising system due to its high energy density(2600 Wh kg^(-1))and low material cost[2].
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21503263,U1632269,21473235,and 11227902)
文摘In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles are studied by soft x-ray absorption spectroscopy in total electron（TEY） and fluorescence（TFY） detection modes, which provide surface and bulk information, respectively. The spectra of Co L2,3-edge indicate that Co contributes to charge compensation below 4.4 V.Combining with the spectra of O K-edge, it manifests that only O contributes to electron compensation above 4.4 V with the formation of local O 2 p holes both on the surface and in the bulk, where the surficial O evolves more remarkably. The evolution of the O 2 p holes gives an explanation to the origin of O2^-or even O2. A comparison between the TEY and TFY of O K-edge spectra of LiCoO2 cycled in a range from 3 V to 4.6 V indicates both the structural change in the bulk and aggregation of lithium salts on the electrode surface are responsible for the capacity fading. However, the latter is found to play a more important role after many cycles.
文摘The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF（1,3,5-Triphenylformazan） amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP （pentachlorophenol） removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.
基金the National Natural Science Foundation of China(Nos.51761032 and 51471054)the Natural Science Foundation of Inner Mongolia,China(No.2015MS0558)
文摘The La-Mg-Ni-Mn-based AB_2-type La_（1-x）Ce_xMgNi_（3.5）Mn_（0.5）（x = 0, 0.1, 0.2, 0.3, and 0.4） alloys were fabricated by melt spinning technology. The effects of Ce content on the structures and electrochemical hydrogen storage performances of the alloys were studied systematically. The XRD and SEM analyses proved that the experimental alloys consist of a major phase LaMgNi_4 and a secondary phase LaNi_5. The variation of Ce content causes an obvious change in the phase abundance of the alloys without changing the phase composition. Namely, with the increase of Ce content, the LaMgNi_4 phase augments and the LaNi_5 phase declines. The lattice constants and cell volumes of the alloys clearly shrink with increasing Ce content. Moreover, the Ce substitution for La results in the grains of the alloys clearly refined. The electrochemical tests showed that the substitution of Ce for La obviously improves the cycle stability of the as-spun alloys. The analyses on the capacity degradation mechanism demonstrate that the improvement can be attributed to the ameliorated anti-corrosion and antioxidation ability originating from substituting partial La with Ce. The as-spun alloys exhibit excellent activation capability, reaching the maximum discharge capacities just at the first cycling without any activation treatment. The substitution of Ce for La evidently improves the discharge potential characteristics of the as-spun alloys. The discharge capacity of the alloys first increases and then decreases with growing Ce content. Furthermore, a similar trend also exists in the electrochemical kinetics of the alloys, including the high rate discharge ability（HRD）, hydrogen diffusion coefficient（D）, limiting current density（IL） and charge transfer rate.
文摘Nickel-rich layered oxides have been identified as the most promising commercial cathode materials for lithium-ion batteries(LIBs)for their high theoretical specific capacity.However,the poor cycling stability of nickel-rich cathode materials is one of the major barriers for the large-scale usage of LIBs.The existing obstructions that suppress the capacity degradation of nickel-rich cathode materials are as a result of phase transition,mechanical instability,intergranular cracks,side reaction,oxygen loss,and thermal instability during cycling.Core–shell structures,oxidating precursors,electrolyte additives,doping/coating and synthesizing single crystals have been identified as effective methods to improve cycling stability of nickel-rich cathode materials.Herein,recent progress of surface modification,e.g.coating and doping,in nickel-rich cathode materials are summarized based on Periodic table to provide a clear understanding.Electrochemical performances and mechanisms of modified structure are discussed in detail.It is hoped that an overview of synthesis and surface modification can be presented and a perspective of nickel-rich materials in LIBs can be given.
基金Project(71525002) supported by China National Funds for Distinguished Young ScientistsProjects(71271023,71210001) supported by the National Natural Science Foundation of ChinaProject(RCS2015ZZ003) supported by the Research Foundation of State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University,China
文摘A model is proposed to describe the passengers’route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand,sensitive and insensitive passenger.The insensitive passengers choose their route without paying much attention to congestion.To the contrary,sensitive passengers who consider route congestion choose travel route based on generalized cost.An equilibrium state is given by variational inequalities in terms of travel generalized cost,which is represented by the combinations of mean and variance of total travel time.The diagonalization algorithm is given to solve this programming.Results show that insensitive passengers have large effects on the path choice than sensitive ones,especially for the larger demand.
基金"973"Project (2002CB211800)Teaching and Research Fund of Beijing Institute of Technology(20070542008)
文摘Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge/discharge process of commercial lithium-ion batteries of mobile telephone, degradation analysis and related mechanisms are put forward and discussed in the paper. The impedance spectra of prismatic commercial lithium-ion batteries are measured at various state of charge after different charge/discharge cycles. The incastared impedance spectra are discussed with a proposed equivalent circuit. Results indicated that the structure change of electrode materials or swell and shrink of crystal lattice, decompose of electrolyte, dissolution of active materials and solid electrolyte interphase film formation are the main reasons leading to the capacity degradation.
基金This project was funded by an industry-academia collaborative grant EPSRC EP/R511687/1 awarded by EPSRC&University of Edin-burgh program Impact Acceleration Account(IAA).G.dos Reis acknowledges support from the Fundaç̃ao para a Cî𝑒ncia e a Tecnologia(Portuguese Foundation for Science and Technology,Por-tugal)through the project UIDB/00297/2020(Centro de Matemática e Aplicaç̃oes CMA/FCT/UNL).
文摘There is a large demand for models able to predict the future capacity retention and internal resistance(IR)of Lithium-ion battery cells with as little testing as possible.We provide a data-centric model accurately predicting a cell’s entire capacity and IR trajectory from one single cycle of input data.This represents a significant reduction in the amount of input data needed over previous works.Our approach characterises the capacity and IR curve through a small number of key points,which,once predicted and interpolated,describe the full curve.With this approach the remaining useful life is predicted with an 8.6%mean absolute percentage error when the input-cycle is within the first 100 cycles.
基金financially supported by the National Natural Science Foundation of China(Nos.51161015 and 51371094)the Application Technology Research and Development Foundation of Inner Mongolia(No.20111401)the Innovation Foundation of Inner Mongolia University of Science and Technology(No.2012NCL024)
文摘In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were investigated in detail.The structural analysis identifies that（La,Mg）Ni3（PuNi3-type） phase transforms to amorphous,i.e.,hydrogen-induced amorphization（HIA） occurs whereas LaNi5（CaCu5-type）,（La,Mg）2Ni7（Ce2Ni7-type）,and（La,Mg）5Ni19（Pr5Co19-type） phases still keep crystalline upon hydriding/dehydriding cycling.Partial amorphization remarkably affects both the gas-solid and electrochemical storage performances.The plateau of PCT curves becomes narrow and steep with cycling.Moreover,the maximum electrochemical capacity decreases notably after gas-solid hydrogenation repeats.The electrochemical capacity reduction could be ascribed to both drop of the maximum storage capacity and the slope of plateau induced by partial amorphization.For direct electrochemical cycling,it is suggested that the capacity decay is mainly attributed to HIA in the initial stage.
