Graphene-loaded nickel−vanadium bimetal oxides as hydrogen pumps to boost solid-state hydrogen storage kinetic performance of magnesium hydride

To modify the thermodynamics and kinetic performance of magnesium hydride(MgH_(2))for solid-state hydrogen storage,Ni_(3)V_(2)O_(8)-rGO(rGO represents reduced graphene oxide)and Ni_(3)V_(2)O_(8)nanocomposites were prepared by hydrothermal and subsequent heat treatment.The beginning hydrogen desorption temperature of 7 wt.%Ni_(3)V_(2)O_(8)-rGO modified MgH_(2)was reduced to 208℃,while the additive-free MgH_(2)and 7 wt.%Ni_(3)V_(2)O_(8)doped MgH_(2)appeared to discharge hydrogen at 340 and 226℃,respectively.A charging capacity of about 4.7 wt.%H_(2)for MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO was achieved at 125℃ in 10 min,while the dehydrogenated MgH_(2)took 60 min to absorb only 4.6 wt.%H_(2)at 215℃.The microstructure analysis confirmed that the in-situ generated Mg_(2)Ni/Mg_(2)N_(i)H_(4) and metallic V contributed significantly to the enhanced performance of MgH_(2).In addition,the presence of rGO in the MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO composite reduced particle aggregation tendency of Mg/MgH_(2),leading to improving the cyclic stability of MgH_(2)during 20 cycles.

Measurement of Thermophysical Property of Energy Storage System (CaCl₂&#46NH₃System)

In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and CaCl2.mNH3 + Ti. It reveals that the thermophysical properties in this measurement would be the valuable design factors to develop energy and H2 storage systems utilizing natural resources such as solar energy.

Lithium Storage Property of Graphite/AlCuFe Quasicrystal Composites

Quasicrystals have long-range quasi-periodic translational ordering and non-crystallographic rotational symmetry.Al-Cu-Fe quasicrystals have great potential for lithium storage because of their high Al content and a large number of defects in the structure.In our previous study(J.Alloys Compd.805(2019)942)we showed that Al-Cu-Fe quasicrystals have good initial capacity whereas its cycle stability is poor.In the present study,graphite/AlCuFe is prepared by the mechanical alloying method.The results show that graphite/AlCuFe quasicrystal composites are successfully synthesized by planetary ball milling at 550 rpm for 80 h.The quasicrystal particle size decreases and the amorphous graphite forms onion-like carbon(OLC)when the two phases mix evenly.OLC forms on the surface of the Al-Cu-Fe quasicrystalline powder.Charge and discharge tests show that graphite/AlCuFe quasicrystal composites have high-stability capacity of 480 mAh/g after 20 cycles,which is larger than the sum of capacities of graphite and Al-Cu-Fe quasicrystals.

Calcium looping heat storage performance and mechanical property of CaO-based pellets under fluidization

The CaO-based pellets were fabricated using extrusion-spheronization method for calcium looping thermochemical heat storage under the fluidization.The effects of adhesive,biomass-based pore-forming agent,binder and particle size on the heat storage performance and mechanical property of the CaObased pellets were investigated in a bubbling fluidized bed reactor.The addition of 2%(mass)polyvinylpyrrolidone as an adhesive not only helps granulate,but also improves the heat storage capacity of the pellets.All biomass-templated CaO-based pellets display higher heat storage capacity than biomass-free pellets,indicating that the biomass-based pore-forming agent is beneficial for heat storage under the fluidization.Especially,bagasse-templated pellets show the highest heat storage conversion of 0.61 after 10 cycles.Moreover,Al_(2)O_(3)as a binder for the pellets helps obtain high mechanical strength.The CaO-based pellets doped with 10%(mass)bagasse and 5%(mass)Al_(2)O_(3)reach the highest heat storage density of 1621 kJ·kg^(-1) after 30 cycles and the highest crushing strength of 4.98 N.The microstructure of the bagasse-templated pellets appears more porous than that of biomass-free pellets.The bagassetemplated CaO-based pellets doped with Al_(2)O_(3)seem promising for thermochemical heat storage under the fluidization,owing to the enhanced heat storage capacity,excellent mechanical strength,and simplicity of the synthesis procedure.

Phase structure and electrochemical properties of La_(0.7)Ce_(0.3)Ni_(3.75)Mn_(0.35)Al_(0.15)Cu_(0.75-x)Fe_x hydrogen storage alloys

La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-xFex （x=0-0.20） hydrogen storage alloys were synthesized by induction melting and subsequent annealing treatment, and phase structure and electrochemical characteristics were investigated. All alloys consist of a single LaNi5 phase with CaCu5 structure, and the lattice constant a and the cell volume （V） of the LaNi5 phase increase with increasing x value. The maximum discharge capacity gradually decreases from 319.0 mA？h/g （x=0） to 291.9 mA？h/g （x=0.20） with the increase in x value. The high-rate dischargeability at the discharge current density of 1200 mA/g decreases monotonically from 53.1% （x=0） to 44.2% （x=0.20）. The cycling stability increases with increasing x from 0 to 0.20, which is mainly ascribed to the improvement of the pulverization resistance.

Preparation of ZrMn_2 hydrogen storage alloy by electro-deoxidation in molten calcium chloride

ZrMn2 alloy was electro-synthesized directly from cathode pellets compacted with powdered mixture of MnO2 and ZrO2 in molten calcium chloride. Sintering temperature, cell voltage and electrolysis time were the dominant factors that affected the characteristics of the final product. The results confirmed the formation of pure ZrMn2 alloy through the electro-deoxidation of the mixed oxide pellets at 3.1 V for 12 h in 900 °C CaCl2 melt. The X-ray diffraction（XRD） and cyclic voltammetry analysis suggested that the electro-deoxidation proceeded from the reduction of manganese oxides to Mn, followed by ZrO2 or CaZrO3 reduction on the pre-formed Mn to ZrMn2 alloy. The cyclic voltammetry measurements using powder microelectrode showed that the prepared ZrMn2 alloy has a good electrochemical hydrogen storage property.

Phase structure and electrochemical properties of La_(1.7+x)Mg_(1.3-x)(NiCoMn)_(9.3)(x=0-0.4) hydrogen storage alloys

The phase structure and electrochemical properties of La1.7＋xMg1.3-x（NiCoMn）9.3（x=0-0.4） alloys were investigated. The XRD analysis reveals that the alloys consist of LaNi5 phase and other phases, such as LaMg2Ni9 phase （PuNi3 structure） and La4MgNi19 phases （Ce5Co19＋Pr5Co19 structure, namely A5B19 type）. With the increase of the x value, the LaMg2Ni9 phase fades away and La4MgNi19 phases appear, while the abundance of LaNi5 phase firstly increases and then decreases. At the same time, the cell volume of LaNi5 phase and LaMg2Ni9 phase decreases. The electrochemical measurement shows that alloy electrodes could be activated in 4-5 cycles, and with the increase of the x value, the maximum discharge capacity gradually increases from 330.9 mA-h/g （x=0） to 366.8 mA-h/g （x=0.4）, but the high-rate dischargeability （HRD） and cyclic stability （S） decrease somewhat （x=0.4, HRD600=82.32%, S100=73.8%）. It is found that the HRD is mainly controlled by the electrocatalytic activity on the alloy electrode surface, and the decline of cyclic stability is due to the appearance of A5B19 type phase with larger hydrogen storage capacity, which leads to larger volume expansion and more intercrystalline stress and then easier pulverization during charging/discharging.

Effects of Storage Temperature on Pasting Properties of Brown Rice

[Objective] The aim of this study was to explore the effects of storage temperature on pasting properties of brown rice.[Method] Rapid viscosity analyzer was used to determine the viscosity of brown rice under different storage temperatures（30,25,20 and 15 ℃）.[Result] The peak viscosity value increased with storage time prolonging.The higher the storage temperature was,the more rapidly the increasing of peak viscosity value;different storage temperatures and storage time showed significant effects on peak viscosity value of brown rice;the difference on peak viscosity value of brown rice under different storage temperatures was significant.The hot viscosity value of brown rice stored under 30 and 25 ℃ gradually increased with the storage time prolonging;and storage time and storage temperature showed significant effects on hot viscosity value;there was extremely significant difference on hot viscosity value of brown rice under 30,25 and 20,15 ℃.The breakdown value showed a first increasing and then decreasing trend with the storage time prolonging;storage temperature and storage time had extremely significant effect on the breakdown value of brown rice;the breakdown value of brown rice among each storage temperature was extremely significant.The final viscosity of brown rice increased with storage time prolonging.The higher the temperature was,the higher the increasing rate of final viscosity;storage time and temperature showed extremely significant effect on the final viscosity of brown rice;the difference on final viscosity among different storage temperature treatments was extremely significant.The changes on setback value of brown rice under different storage temperature treatments were different with the storage time prolonging;and the storage temperature showed extremely significant effect on the setback value of brown rice.[Conclusion] The study had provided theoretical basis for the storage of brown rice.

Electrochemical hydrogen storage characteristics of Ti_(0.10)Zr_(0.15)V_(0.35)Cr_(0.10)Ni_(0.30)-10% LaNi_3 composite and its synergetic effect

Hydrogen storage composite alloy Ti0.10Zr0.15V0.35Cr0.10Ni0.30–10% LaNi3 was prepared by two-step arc-melting to improve the electro-catalytic activity and the kinetic performance of Ti-V-based solid solution alloy. The electrochemical properties and synergetic effect of the composite alloy electrode were systematically investigated by using X-ray diffractometry, field emission scanning electron microscopy, energy-dispersive spectrometry, electrochemical impedance spectroscopy and galvanostatic charge/discharge test. It is found that the main phase of the composite alloy is composed of V-based solid solution phase with a BCC structure and C14 Laves phase with hexagonal structure, while the secondary phase is formed in the composite alloy. The comprehensive electrochemical properties of the composite alloy electrode are significantly improved. The activation cycle number, the maximum discharge capacity and the low temperature dischargeability of the composite alloy are 5 cycles, 362.5 mA-h/g and 65.84% at 233 K, respectively. It is suggested that distinct synergetic effect occurs in the activation process, composite process, cyclic process and discharge process at a low or high temperature under different current densities, in the charge–transfer resistance and exchange current density.

Preparation of LaMgNi_(4-x)Co_x alloys and hydrogen storage properties

The LaMgNi4xCox （x=0, 0.3, 0.5） compounds were prepared by the method of levitation melting and a subsequent heat treatment at 1073 K for 10 h. XRD analysis shows that the obtained LaMgNia-xCox alloys consist of a single phase with the structure of cubic SnMgCu4 （AuBe5 type）. The hydrogen absorption/desorption properties of LaMgNi4 were investigated by PCI measurement at various temperatures （T=373, 398, 423 K） and the results show that the maximum absorbed hydrogen capacity reaches 1.45% （5.79H/M） under a hydrogen pressure of 4.3 MPa at 373 K. The XRD patterns during absorbing procedure at 373 K indicate the phase structure changing from cubic （a-LaMgNi4） to orthorhombic （fl-LaMgNiaH3.41） and after hydrogenation finally back to cubic （y-LaMgNiaH4.87）, and a partial desorption was also observed under this condition. With increasing temperature, a slight decrease of the absorbed hydrogen content was observed and the number of plateaus reduces from two to one, but the hydrogen absorption kinetics improves. The electrochemical properties of the LaMgNiaxCox were measured by simulated battery test, which shows that the discharge capacity of the alloys significantly improves with the increase of Co content.

Catalytic effect of SrTiO_3 on the hydrogen storage behaviour of MgH_2

The effects of Sr TiO_3 on the hydrogen storage properties of MgH_2 have been studied for the first time.The onset dehydrogenation temperature of the MgH_2-10 wt% SrTiO_3 is found to be 275 ℃, which is 55 ℃ lower as compared to the as-milled MgH_2. The composite is able to absorb 4.3 wt% of hydrogen in 60 min instead of 1.1 wt% for the as-milled Mg H_2. Meanwhile, the composite is able to release 5.3 wt% of hydrogen in 17 min compared to 1.9 wt% by the as-milled Mg H_2 at 320 ℃. The calculated Eaof the Mg H_2-10 wt% SrTiO_3 is 109 k J/mol, which is 26.3 kJ/mol lower than the calculated Eaof the as-milled MgH_2. The Sr TiO_3 is not decomposed during the ball milling and the re/dehydrogenation processes. The catalytic effect shown by the SrTiO_3 is owing to its ability to change the physical structure of the MgH_2 particles during the ball milling process.

Effect of vegetation on soil water retention and storage in a semi-arid alpine forest catchment

The runoff generated from mountainous regions is recognized as the main water source for inland river basins in arid environments. Thus, the mechanisms by which catchments retain water in soils are to be understood. The water storage capacity of soil depends on its depth and capacity to retain water under gravita- tional drainage and evapotranspiration. The latter can be studied through soil water retention curve （SWRC）, which is closely related to soil properties such as texture, bulk density, porosity, soil organic carbon conteMt, and so on. The present study represented SWRCs using HYDRUS-1D. In the present study, we measured pl^ysical and hydraulic properties of soil samples collected from Sabina przewalskii forest （south-facing slope with highest solar radiation）, shrubs （west-facing slope with medium radiation）, and Picea crassifolia forest （north-facing slope with lowest radiation）, and analyzed the differences in soil water storage capacity of these soil samples. Soil water content of those three vegetation covers were also measured to validate the soil water storage capacity and to analyze the relationship between soil organic matter content and soil water content. Statistical analysis showed that different vegetation covers could lead to different soil bulk densities and differences in soil water retention on the three slope aspects. Sand content, porosity, and organic carbon content of the P. crassifolia forest were rela- tively greater compared with those of the S. przewalskii forest and shrubs. However, silt content and soil bulk density were relatively smaller than those in the S. przewalskii forest and shrubs. In addition, there was a sig- nificant linear positive relationship between averaged soil water content and soil organic matter content （P〈0.0001）. However, this relationship is not significant in the P. crassifolia forest. As depicted in the SWRCs, the water storage capacity of the soil was 39.14% and 37.38% higher in the P. crassifolia forest than in the S. przewalskii forest and shrubs, respectively, at a similar soil depth.

Effect of stoichiometry and Cu-substitution on the phase structure and hydrogen storage properties of Ml-Mg-Ni-based alloys

To improve the electrochemical properties of rare-earth-Mg-Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the alloys were studied. Nonsubstituted Ml0.80Mg0.20（Ni2.90Co0.50-Mn0.30Al0.30）x （x=0.68, 0.70, 0.72, 0.74, 0.76） alloys and Cu-substituted Ml0.80Mg0.20（Ni2.90Co0.50-yCuyMn0.30Al0.30）0.70 （y=0, 0.10, 0.30, 0.50） alloys were prepared by induction melting. Phase structure analysis shows that the nonsubstituted alloys consist of a LaNi5 phase, a LaNi3 phase, and a minor La2Ni7 phase;in addition, in the case of Cu-substitution, the Nd2Ni7 phase appears and the LaNi3 phase vanishes. Ther-modynamic tests show that the enthalpy change in the dehydriding process decreases, indicating that hydride stability decreases with in-creasing stoichiometry and increasing Cu content. The maximum discharge capacity, kinetic properties, and cycling stability of the alloy electrodes all increase and then decrease with increasing stoichiometry or increasing Cu content. Furthermore, Cu substitution for Co ame-liorates the discharge capacity, kinetics, and cycling stability of the alloy electrodes.

Effects of annealing treatment on the microstructure and electrochemical properties of low-Co hydrogen storage alloys containing Cu and Fe

The effects of annealing treatment on the microstructure and electrochemical properties of low-Co LaNi 3.55 Mn 0.35 Co 0.20 Al 0.20 Cu 0.75 Fe 0.10 hydrogen storage alloys were investigated. X-ray diffraction （XRD） analysis indicated that annealing treatment remarkably reduced the lattice strain and defects, and increased the unit-cell volume. The optical microscope analysis showed that the as-cast alloy had a crass dendrite microstructure with noticeable composition segregation, which gradually disappeared with increasing annealing temperature, and the micro-structure changed to an equiaxed structure after annealing the alloy at 1233 K. The electrochemical tests indicated that the annealed alloys demonstrated much better cycling stability compared with the as-cast one. The capacity retention at the 100th cycle increased from 90.0% （as-cast） to 94.7% （1273 K）. The annealing treatment also improved the discharge capacity. However, the high rate dischargeability （HRD） value of the annealed alloy slightly dropped, which was believed to be ascribed to the decreased exchange current density and the hydrogen diffusion coefficient in alloy bulk.

Effect of Ti substitution on hydrogen storage properties of Zr_(1-x)Ti_xCo (x = 0, 0.1, 0.2, 0.3) alloys

Zr1-xTixCo(x = 0, 0.1, 0.2, 0.3) alloys were prepared by arc-melting method and the effect of Ti substitution on hydrogen storage properties was studied systematically. Hydrogen desorption pressure-composition-temperature(PCT) measurements were carried out using Sievert’s type volumetric apparatus for ZrCo(at 473 K, 573 K and 673 K) and Zr1-xTixCo alloys(at 673 K), respectively. Products after dehydrogenation were characterized by X-ray diffraction(XRD). In addition, the kinetics of Zr1-xTixCo hydride was investigated at 473 K and 673 K,respectively, under hydrogen pressure of 5 MPa. Results showed that Ti substitution for Zr did not change the crystal structure of ZrCo phase.With the increase of temperature from 473 K to 673 K, the extent of disproportionation for ZrCo alloy increased. With Ti content increasing at 673 K, the desorption equilibrium pressure of Zr1-xTixCo-H2 systems elevated and the disproportionation reaction of Zr1-xTixCo alloys was inhibited effectively. Ti substitution decreased the kinetics rate and the effective hydrogen storage capacity of Zr1-xTixCo alloys slightly.Generally speaking, it was found that Zr0.8Ti0.2Co alloy had better anti-disproportionation property with less decrease of effective hydrogen storage capacity which was beneficial to tritium application in the International Thermonuclear Experimental Reactor(ITER).

Hydrogen Storage Properties of Ti_(1.2)Fe+xCa Hydrogen Storage Alloys

The hydrogen storage properties of Ti1.2Fe+xCa (x=1%, 3% and 5% in mass fraction) alloys was investigated. Results stow that the modified alloys can be activated without any thermal treatment at room temperature due to the addition of Ca and excess Ti in (lie alloys. Hydrogen storage properties of these modified alloys vary with Ca amount and reaction temperature. In addition, the influence mechanism of the addition of Ca and excessive Ti on the activation behavior and hydrogen storage capacity of the alloys was discussed.

Effect of praseodymium substitution for lanthanum on structure and properties of La_(0.65-x)Pr_xNd_(0.12)Mg_(0.23)Ni_(3.4)Al_(0.1)(x=0.00–0.20) hydrogen storage alloys

In order to investigate the effect of substituting La with Pr on structural and hydrogen storage properties of La-Mg-Ni system （AB3.5-type） hydrogen storage alloys, a series of La0.65-xPrxNd0.12Mg0.23Ni3.4Al0.1（x=0, 0.10, 0.15, 0.2） hydrogen storage alloys were prepared. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive spectrometer （EDS） analyses revealed that two alloys （x=0.0 and 0.10） were composed of （La,Mg）2（Ni,Al）7 phase, La（Ni,A1）5 phase and （La,Mg）Ni2 phase, while other alloys （x=0.15 and 0.20） consisted of （La,Mg）2（Ni,A1）7 phase, La（Ni,A1）5 phase, （La,Mg）Ni2 phase and （La,Mg）（Ni,A1）3 phase. All alloys showed, however, only one pressure plateau in P-C isotherms. The Pr/La ratio in alloy composition influenced hydrogen storage capacity and kinetics properties. Electrochemical studies showed that the discharge capacity decreased from 360 mAh/g （x=-0.00） to 335 mAh/g （x=-0.20） as x increased. But the high-rate dischargeability （HRD） of alloy electrodes increased from 26% （x=0.00） to 56% （x=-0.20） at a discharge current density of Id=1800 mA/g. Anode polarization measurements were done to further understand the electrochemical kinetics properties after Pr substitution.

Phase structure and hydrogen storage properties of LaMg_(3.70)Ni_(1.18) alloy

The phase structure and hydrogen storage properties of LaMg 3.70 Ni 1.18 alloy were investigated. The LaMg 3.70 Ni 1.18 alloy consists of main LaMg 2 Ni phase, minor La 2 Mg 17 and LaMg 3 phases. The alloy can be activated in the first hydriding/dehydriding process, and initial LaMg 2 Ni, La 2 Mg 17 , and LaMg 3 phases transfer to LaH 2.34 , Mg, and Mg 2 Ni phases after activation. The reversible hydrogen storage capacity of the LaMg 3.70 Ni 1.18 alloy is 2.47 wt.% at 558 K, which is higher than that of the LaMg 2 Ni alloy. The pressure-composition-temperature （PCT） curves display two hydriding plateaus, corresponding to the formation of MgH 2 and Mg 2 NiH 4 . However, only one dehydriding plateau is observed, owing to the synergetic effect of hydrogen desorption between MgH 2 and Mg 2 NiH 4 . The uptake time for hydrogen content to reach 99% of saturated state is less than 250 s, and 90% hydrogen can be released in 1200 s in the experimental conditions, showing fast kinetics in hydriding and dehydriding. The activation energies of the LaMg 3.70 Ni 1.18 alloy are –51.5 ± 1.1 kJ/mol and –57.0 ± 0.6 kJ/mol for hydriding and dehydriding, respectively. The hydriding/dehydriding kinetics of the LaMg 3.70 Ni 1.18 alloy is better than that of the Mg 2 Ni alloy, owing to the lower activation energy values.

Effect of Ni,Fe and Fe-Ni alloy catalysts on the synthesis of metal contained carbon nano-onions and studies of their electrochemical hydrogen storage properties

Three types of carbon nano-onions（CNOs） including Ni@CNOs.Fe3C@CNOs and Fe0.64Ni0.36@CNOs nanoparticles have been synthesized by catalytic decomposition of methane at 850 ℃ using nickel,iron and iron-nickel alloy catalysts.Comparative and systematic studies have been carried out on the morphology,structural characteristics and graphitic crystallinity of these CNOs products.Furthermore,the electrochemical hydrogen storage properties of three types of CNOs have been investigated.Measurements show that the Ni@CNOs have the highest discharge capacity of 387.2 mAh/g,coiTesponding to a hydrogen storage of 1.42%.This comparison study shows the advantages of each catalyst in the growth of CNOs.enabling the controllable synthesis and tuning the properties of CNOs by mediating different metals and their alloy for using in the fuel cell system.

Effects of Strip Casting and Annealing on Electrochemical Properties of LPCNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3) Hydrogen Storage Alloys

The effect of thickness (1 similar to 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the 0.2 C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4Al0.3 alloy increases with the increase of the thickness of the ingots. As-east alloy with the thickness of 10 mm shows better activation property, higher 1C discharge capacity and better cyclic stability than others. It is mainly contributed to its larger unit cell volume and less internal stress. Annealed LPCNi3.55Co0.75Mn0.4Al0.3 alloy with the thickness of 3 mm shows much better comprehensive electrochemical properties than as-east one; The cyclic. stability of the alloy with the thickness of 6 mm and the activation properties of the alloys with the thickness of 3 similar to 6 mm are improved after annealing. It is mainly owing to the great release of internal stress and the decrease of the segregation of Mn in the alloys.