Preparation and Electrochemical Performances of Nickel Metal Hydride Batteries with High Specific Volume Capacity

Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.

The electrochemical characteristics of AB_(4)-type rare earth-Mg-Ni-based superlattice structure hydrogen storage alloys for nickel metal hydride battery

Rare earth-Mg-Ni-based alloys with superlattice structures are new generation negative electrode materials for the nickel metal hydride batteries.Among them,the novel AB_(4)-type superlattice structure alloy is supposed to have superior cycling stability and rate capability.Yet its preparation is hindered by the crucial requirement of temperature and the special composition which is close to the other superlattice structure.Here,we prepare rare earth-Mg-Ni-based alloy and study the phase transformation of alloys to make clear the formation of AB_(4)-type phase.It is found Pr_(5)Co_(19)-type phase is converted from Ce_(5)Co_(19)-type phase and shows good stability at higher temperature compared to the Ce_(5)Co_(19)-type phase in the range of 930-970℃.Afterwards,with further 5℃increasing,AB_(4)-type superlattice structure forms at a temperature of 975℃by consuming Pr_(5)Co_(19)-type phase.In contrast with A_(5)B_(19)-type alloy,AB_(4)-type alloy has superior rate capability owing to the dominant advantages of charge transfer and hydrogen diffusion.Besides,AB_(4)-type alloy shows long lifespan whose capacity retention rates are 89.2%at the 100;cycle and 82.8%at the 200;cycle,respectively.AB_(4)-type alloy delivers 1.53 wt.%hydrogen storage capacity at room temperature and exhibits higher plateau pressure than Pr_(5)Co_(19)-type alloy.The work provides novel AB_(4)-type alloy with preferable electrochemical performance as negative electrode material to inspire the development of nickel metal hydride batteries.

High-performance nickel metal hydride battery anode with enhanced durability and excellent low-temperature discharge capability

Current AB_(5)-type hydrogen storage alloys employed in nickel-metal hydride(NiMH)batteries exhibit exceptional low-temperature discharge performance but suffer from limited cycle life and insufficient high-temperature stability.To overcome these challenges,we introduce a hydrothermal synthesized LaF_(3)coating layer on the surface of the AB_(5)anode material.This LaF_(3)coating layer adds a protective barrier for the active material,significantly improving the battery's cycle life and high-temperature stability.Our findings indicate that(1)the LaF_(3)coated anode demonstrates an extended cycle life with increased specific capacity and a capacity retention of 88%after 40 cycles of abusive overcharging and rapid discharging at room temperature.(2)The synthesized anode exhibits a 97%recovery of its specific capacity of 292.7 mAh/g following 144 h of high-temperature storage.(3)The low-temperature discharge capacity of the synthesized anode remains on par with the pristine AB_(5)alloy at 230.4 mAh/g in a-40℃environment.This research presents a significant advancement in hydrogen storage alloy coatings and offers valuable insights for designing electrodes in NiMH batteries.

Effect of Overcharge on Electrochemical Performance of Sealed-Type Nickel/Metal Hydride Batteries

The effects of overcharge on electrochemical performance of AA size sealed-type nickel/metal hydride（Ni/MH） batteries and its degradation mechanism were investigated. The results indicated that the relationship between the effects of different overcharge currents on the increasing velocity of inner pressure and the degradation velocity of cycle life and discharge voltage remains in almost direct proportion. After overcharge cycles, the positive electrode materials remain the original structure, but there occur some breaks because of the irreversible expand of crystal lattice. And the negative electrode alloy particles have inconspicuous pulverization, but are covered with lots of corrosive products and its main component is rare earth hydroxide or oxide. These are all the main reasons leading to the degradation behavior of the discharge capacity and cycle life of Ni/MH batteries.

CoO AS ADDITIVE IN POSITIVE ELECTRODE OF NICKEL-METAL HYDRIDE BATTERY

A series of positive electrodes for Ni/MH battery were fabricated by addition of CoO.The morphology and microstructure of the electrodes were examined by SEM and EDS, and electrochemical behavior was investigated in three-compartment appliances at room temperature.The electrochemical performance of the positive electrodes with CoO was improved. Under the same charge-discharge cycle, the electrodes with CoO showed higher specific capacity, lower charge mean voltage and higher discharge mean voltage. But ...

Yttria promoted metallic nickel catalysts for the partial oxidation of methane to synthesis gas

A metallic Ni catalyst was prepared with nickel sponge, followed by acid treatment. It was further promoted with yttria by an impregnation method. The catalysts were characterized by SEM, BET, XRD, TPR, XPS, etc., and studied in the partial oxidation of methane to syngas. The characterization results showed that the yttria promoted metallic Ni catalysts had high specific surface area and more NiO. The reaction results showed that the yttria promoter increased the CH4 conversion and the selectivity for H2 and CO.

Electrode Characteristics of MmNi_5－type Alloys for Nickel－metal HydrideBatteries

Negative electrodes of the nickel-metal hydride battery were made from hydrogen storage alloy Mm0.9Ti0.1Ni3.9Mn0.4Co0.4Al0.3 modified by coating with nickei and mixing with cobalt powder. When the 10wt% cobalt powder was mixed with this alloy, the discharge capacity increased from 262 mAh/g to 300 mAh/g at 300K. When the alloy was coated with 11wt% nickel and mixed with 10wt% cobalt powder, the discharge capacity decay for a sealed cell (AA size, 1 Ah) was only about 4% after 200 cycles.

Effects of specific surface area of metallic nickel particles on carbon deposition kinetics

Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I（D）/I（G） of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.

Formation of Copper Nickel Bimetallic Nanoalloy Film Using Precursor Inks

Precursor (Metal-organic decomposition (MOD)) inks are used to fabricate 2D and 3D printed conductive structures directly onto a substrate. By formulating a nanoalloy structure containing multiple metals, the opportunity to modify chemical and physical properties exists. In this paper, a copper-nickel bimetallic nanoalloy film was fabricated by mixing copper and nickel precursor inks and sintering them in vacuum. The individual elemental inks were formulated and characterized using SEM, EDS, and XRD. During thermal processing, elemental copper forms first and is followed by the formation of bimetallic copper-nickel alloy. The encapsulation of the underlying copper by the nickel-rich alloy provides excellent oxidation resistance. No change in film resistance was observed after the film was exposed to an oxygen plasma. Nanoalloy films printed using reactive metallic inks have a variety of important applications involving local control of alloy composition. Examples include facile formation of layered nanostructures, and electrical conductivity with oxidative stability.

Crystallization of amorphous silicon beyond the crystallized polycrystalline silicon region induced by metal nickel

Crystallization of amorphous silicon（a-Si） which starts from the middle of the a-Si region separating two adjacent metal-induced crystallization（MIC） polycrystalline silicon（poly-Si） regions is observed. The crystallization is found to be related to the distance between the neighboring nickel-introducing MIC windows. Trace nickel that diffuses from the MIC window into the a-Si matrix during the MIC heat-treatment is experimentally discovered, which is responsible for the crystallization of the a-Si beyond the MIC front. A minimum diffusion coefficient of 1.84×10^-9cm^2/s at 550℃ is estimated for the trace nickel diffusion in a-Si.

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis

With the aid of thermomagnetic analysis (TMA) up to 800ºС the composition and distribution of particles of native iron and Fe-Ni alloy was studied in 15 sections, Gams (Austria), Verhorechie and Selbuhra (Crimea), Kvirinaki and Tetritskaro (Georgia), Aimaki, Bass, Dzhengutaj, Madzhalis and Gergebil (North Caucasus, Russia), Klyuchi and Tep-lovka (Volga Region, Russia), Koshak (Kazakhstan), Kara-Kala and Khalats (Turkmenistan). The age of sediments varies from Miocene to Early Cretaceous. Iron particles are present at 521samples out of 921studied. Their percentage varies from 10-5% to 0.05%. The distribution consists of two groups: 1) “zero” group (iron is not found by TMA);2) group of logarithmic normal distribution with a differing modes. The global enrichment by iron particles in synchronous deposits of Miocene, Maastrichtian-Danian, Santonian and Cenomanian was discovered. With respect to nickel content, the iron particles fall into two groups: 1) nearly pure iron without nickel;and 2) iron with nickel content up to 20%, with modal value of 5%. The source of iron particles is the cosmic dust. Particles of pure nickel and the alloy containing more of 20% of nickel are very rare. Possibly, such particles are related mainly with impact events. A peak of elevated iron content with nearly constant nickel of 5-6% was found in almost all studied sections. It is a global effect which is not dependent of place and time of deposition of iron particles.

黄铜集流体在无负极锂金属电池中的应用研究

虽然无负极锂金属电池(AF-LMBs)具有能量密度高、结构简单等优势,但是金属锂在负极集流体界面不可逆的沉积/剥离过程以及与电解液之间的副反应会大量消耗电池中有限的活性锂,导致电池容量迅速衰减。开发高性能的负极集流体是提升AF-LMBs循环寿命的有效策略之一。因此,本文研究了商业黄铜箔(F-Cu-Zn)作为负极集流体在AF-LMBs中的电化学性能,并且结合多种表征技术揭示了F-Cu-Zn电极在循环过程中的结构演变。结果表明:与商业铜箔(F-Cu)相比,F-Cu-Zn含有丰富的亲锂位点,诱导金属锂均匀成核与生长,所组装的Cu-Zn||NCM712软包全电池的室温循环寿命从75次增加至117次。此外,F-Cu-Zn电极中的Zn元素会在循环过程中不断溶解,最终在电极表层形成三维多孔结构。

镍闪速炉熔炼共生产品生命周期评价碳排放分配问题

金属镍生产是典型的多元素共生冶炼过程,清单分配问题是制约其生命周期评价准确性的重要技术因素。以共生反应最为密集的硫化镍矿闪速炉熔炼流程为研究对象,采取边界扩展、物理关联、质量分配等多种清单分配方法,在Ni、Cu、S这3种元素之间进行CO_(2)排放分配。边界扩展分配计算结果显示,非金属共生元素与金属产物之间的分配结果为29.86%,金属共生元素之间的分配结果为70.14%。对比分析结果显示,边界扩展方法对于中间态产物的适用性较差;物理关联分配结果准确,但需要大量流程工艺参数支撑;质量分配易于计算,但其准确性取决于共生产品之间的物理化学属性差异。

高流速离子源辉光放电质谱校正灵敏度因子法定量分析镍基高温合金中痕量稀土及贵金属元素

该文通过全面优化高流速辉光放电离子源分析高温合金痕量元素的仪器条件,系统研究高温合金复杂基体元素造成的质谱干扰,选取稀土元素和贵金属元素分析同位素与合适的质谱分辨率,确立了基于基体匹配的变形高温合金标准物质系列的校正灵敏度因子(RSF)定量方案,使测定结果的相对误差由4.0%~80%优化至7.7%~20%,并为痕量分析结果提供了可靠的计量溯源依据。基于此所建立的辉光放电质谱(GDMS)测定镍基高温合金中稀土元素和贵金属元素的方法检出限为0.0010~0.015μg/g,定量下限为0.0030~0.045μg/g。应用于变形高温合金和铸造高温合金实际样品中稀土元素和贵金属元素的分析,测定结果与湿法分析的参考值吻合较好,较好地验证了辉光放电固体样品快捷分析的优势,体现了高分辨质谱检出限低、线性范围宽、可分析元素多的特点,在高温合金材料质控中有着巨大的应用前景。

MOF-74协同膨胀阻燃EVA及其性能研究

将一种镍基金属有机框架材料(MOF-74)与焦磷酸哌嗪(PPAP)及三嗪成炭剂(CFA)以一定的质量比均匀混合后加入到乙烯-醋酸乙烯酯树脂(EVA)中,制备阻燃EVA材料并对其性能进行了表征。结果表明,PPAP/CFA(IFR)的质量比为3∶1,添加量为19%(质量分数,下同),材料在垂直燃烧测试时通过了UL 94 V-0级,极限氧指数(LOI)为26.9%;当IFR/MOF-74的质量比为97∶3,添加量为18%时,材料就能通过UL 94 V-0级,LOI值为27.1%;锥形量热测试表明,MOF-74的加入有效降低了材料的热量、烟气及一氧化碳的释放,表现了良好的协同阻燃作用,同时提高了阻燃剂与聚合物的相容性,使得阻燃EVA材料保持了良好的力学性能。

混合钎料对镍基单晶高温合金大间隙钎焊接头组织和性能的影响

【目的】采用一种新型镍基钎料和母材成分一致的高熔点合金粉混合的方法制备出混合钎料,研究了添加的高熔点合金粉的粒径和配比对钎缝微观组织和力学性能的影响。【方法】采用扫描电子显微镜对钎焊接头的析出相、元素分布、微观组织进行了分析,并对钎焊接头的硬度及持久性能进行了测试。【结果】研究表明,接头主要由钎料合金区(FAZ)、界面连接区(IBZ)和扩散影响区(DAZ)三部分组成。钎料合金区主要由M3B2和M8B型硼化物及γ/γ′相组成。界面连接区由γ和γ′沉淀强化相组成。当合金粉粒径为44μm和75μm时,均可得到无缺陷的焊接接头;但当合金粉粒径尺寸达177μm时,钎缝内会形成孔洞缺陷。【结论】随着合金粉比例的提高,接头连接区的显微硬度有所上升。当合金配比由30%到50%,接头的持久寿命由15 h增加至34 h;但进一步提升比例至60%时,接头的持久寿命下降至0.6 h。该文的结果可为实现高温热端零部件的连接和修复工程应用提供理论依据和参考价值。

动力氢镍电池市场现状与前景

金属氢化物镍(氢镍)电池在新能源汽车领域占据重要地位。分析氢镍电池在新能源汽车市场的竞争力,探讨技术特点、市场规模、发展前景及面临的机遇与挑战。通过技术创新提升氢镍电池的性能,可满足市场的需求。氢镍电池面临着原材料价格波动及其他类型电池的挑战,虽具有经济竞争力,但仍需持续创新,以应对未来新能源汽车市场的需求。

金属有机框架衍生镍纳米颗粒在宽电位窗口内高效电催化二氧化碳还原

电催化二氧化碳(CO_(2))还原被认为是将CO_(2)转化为可再生能源产品的一种有前途的方法。开发性能优异的电催化剂高效完成这一重要反应是关键。镍基催化剂广泛应用于电催化CO_(2)还原研究,但是,镍纳米颗粒经常表现较差的催化性能。在本文中,通过在氮气气氛中高温热解镍基金属有机骨架(MOF)、尿素和炭黑混合物,获得了镍纳米颗粒负载于多孔碳氮中的催化材料(NiNPs-NC)。有趣的是,NiNPs-NC在H型和流动相电池中都表现出优异的CO_(2)电还原性能。在H型电解池和-0.67–-1.07 V vs.RHE(可逆氢电极)电位窗口内,NiNPs-NC催化CO_(2)还原为CO的法拉第效率大于90%,其中,在-0.87 V vs.RHE时,CO的法拉第效率约为100%。在流动相电解池和-0.50–-0.70 V vs.RHE电位窗口内,NiNPs-NC催化CO_(2)还原为CO的选择性大于95%。电化学阻抗谱图和塔菲尔斜率表征显示,NiNPs-NC的高催化活性归因于其在催化过程中的快速电荷转移。本文提供了一种制备高效CO_(2)电还原催化剂的方法。

还原介质对镍渣直接还原提铁的影响

如何从富铁镍渣中高效提铁是该资源综合再利用的关键。本文采用焦炭和烟煤作为还原剂,对镍渣进行直接还原提铁试验研究,对比两种还原剂在镍渣还原过程中产生有效还原介质的差异,借助热力学软件对不同还原介质的还原能力进行热力学分析,然后通过试验及表征研究两种还原剂对镍渣还原过程金属化率变化及微观结构演变的影响。结果表明:烟煤含有的高挥发分会产生CO-H_(2)混合的还原介质,而焦炭则主要以CO还原介质为主;热力学分析结果表明,CO-H_(2)混合气对铁氧化物的还原能力优于纯CO。镍渣还原焙烧试验结果显示,使用烟煤作为还原剂,1 300℃下还原20 min,镍渣球团的金属化率可达90.20%;而采用焦炭作为还原剂时其金属化率仅达到72.97%,烟煤对镍渣的还原能力优于焦炭。

SA508-3/690异种金属焊接接头显微组织及裂纹形成机理

镍基焊材52M因具有优异的抗晶间腐蚀性和耐蚀性,被广泛应用在核电站关键部位的焊接。通过焊条电弧焊用焊材52M焊接低合金钢SA508Gr.3Cl.2和镍基Inconel690合金。结合光学显微镜和扫描电子显微镜分析熔合边界附近的微观组织、成分分布及析出相,探究其对熔敷金属内裂纹形成及硬度变化的影响。结果表明:隔离层熔合边界附近形成Ⅰ型边界、Ⅱ型边界、半岛状组织及岛状组织;S、Nb、Mo元素在局部晶界偏析发生共晶反应引起液化,进而导致在熔敷金属中形成少量结晶裂纹;由于Nb、Mo、Cr等元素的固溶强化作用,熔敷金属的显微硬度略高于两侧母材。