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.

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.

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 ...

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.

Understanding the catalysis of chromium trioxide added magnesium hydride for hydrogen storage and Li ion battery applications

This study explores how the chemical interaction between magnesium hydride(MgH_(2))and the additive CrO_(3) influences the hydrogen/lithium storage characteristics of MgH_(2).We have observed that a 5 wt.%CrO_(3) additive reduces the dehydrogenation activation energy of MgH_(2) by 68 kJ/mol and lowers the required dehydrogenation temperature by 80℃.CrO_(3) added MgH_(2) was also tested as an anode in an Li ion battery,and it is possible to deliver over 90%of the total theoretical capacity(2038 mAh/g).Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH_(2).In depth characterization study by X-ray diffraction(XRD)technique provides convincing evidence that the CrO_(3) additive interacts with MgH_(2) and produces Cr/MgO byproducts.Gibbs free energy analyses confirm the thermodynamic feasibility of conversion from MgH_(2)/CrO_(3) to MgO/Cr,which is well supported by the identification of Cr(0)in the powder by X ray photoelectron spectroscopy(XPS)technique.Through high resolution transmission electron microscopy(HRTEM)and energy dispersive spectroscopy(EDS)we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt nanoparticles.There is also convincing ground to consider that MgO rock salt accommodates Cr in the lattice.These observations support the argument that creation of active metal–metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH_(2),both for the improved storage of hydrogen and lithium.

Homogenous metallic deposition regulated by abundant lithiophilic sites in nickel/cobalt oxides nanoneedle arrays for lithium metal batteries

Although lithium(Li)metal delivers the highest theoretical capacity as a battery anode,its high reactivity can generate Li dendrites and"dead"Li during cycling,resulting in poor reversibility and low Li utilization.Inducing uniform Li plating/stripping is the core of solving these problems.Herein,we design a highly lithiophilic carbon film with an outer sheath of the nanoneedle arrays to induce homogeneous Li plating/stripping.The excellent conductivity and 3D framework of the carbon film not only offer fast charge transport across the entire electrode but also mitigate the volume change of Li metal during cycling.The abundant lithiophilic sites ensure stable Li plating/stripping,thereby inhibiting the Li dendritic growth and"dead"Li formation.The resulting composite anode allows for stable Li stripping/plating under 0.5 mA cm^(-2) with a capacity of 0.5 mA h cm^(-2) for 4000 h and 3 mA cm^(-2) with a capacity of3 mA h cm^(-2) for 1000 h.The Ex-SEM analysis reveals that lithiophilic property is different at the bottom,top,or channel in the structu re,which can regulate a bottom-up uniform Li deposition behavior.Full cells paired with LFP show a stable capacity of 155 mA h g^(-1) under a current density of 0.5C.The pouch cell can keep powering light-emitting diode even under 180°bending,suggesting its good flexibility and great practical applications.

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.

Recovery of rare earths from acid leach solutions of spent nickel-metal hydride batteries using solvent extraction

The extraction of rare earths from acid leach solutions of spent nickel-metal hydride batteries using a primary amine ex- tractant of N 1923 was studied. The effects of feed pH, temperature, agitation rate and time on the extraction of rare earths, as well as stripping agent composition and concentration, phase ratio on the stripping were investigated. In addition, the extraction isotherm was determined. The pilot plant test results showed that the extraction of rare earths reached 99.98% after a five-stage counter current extraction. The mixed rare earths oxalates with the 99.77% purity of rare earth elements and impurity content less than 0.05% were obtained by the addition of oxalic acids in loaded strip liquors. The extractant exhibited good selectivity of rare earths over base metals of iron, nickel, copper and manganese.

Effects of Annealing Temperature on Microstructure and Electrochemical Properties of Perovskite-type Oxide LaFeO3 as Negative Electrode for Metal Hydride/Nickel（MH/Ni） Batteries

We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction（XRD） patterns show that the annealed LaFeO3 powder has orthorhombic structure. Scanning electron microscopy（SEM） and transmission electron microscopy（TEM） images show the presence of homogeneously dispersed, less aggregated, and small crystals（30--40 nm） at annealing temperatures of 500 and 600 ℃. However, as the annealing temperature was increased to 700 and 800 ℃, the crystals began to combine with each other and grew into further larger crystals（90--100 nm）. The electrochemical performance of the annealed oxides was measured at 60 ℃ using chronopotentiometry, potentiodynamic polarization, and cyclic voltammetry. As the annealing temperature increased, the discharge capacity and anti-corrosion ability of the oxide electrode first increased and then decreased, reaching the optimum values at 600 ℃, with a maximum discharge capacity of 563 mA-h/g. The better electrochemical performance of LaFeO3 annealed at 600℃ could be ascribed to their smaller and more homogeneous crysals.

Effects of flaky rare earth oxide additives on the high temperature performance of nickel electrodes

Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...

Microstructural analyses of all-solid-state Li–S batteries using LiBH4-based solid electrolyte for prolonged cycle performance

Complex hydride materials have been widely investigated as potential solid electrolytes because they have good compatibility with the lithium metal anodes used in all-solid-state batteries. However, the development of all-solid-state batteries utilizing complex hydrides has been difficult as these cells tend to have short cycle lives. This study investigated the capacity fading mechanism of all-solid-state lithium–sulfur(Li–S) batteries using Li4(BH4)3I solid electrolytes by analyzing the cathode microstructure. Crosssectional scanning electron microscopy observations after 100 discharge–charge cycles revealed crack formation in the Li4(BH4)3I electrolyte and an increased cathode thickness. Raman spectroscopy indicated that decomposition of the Li4(BH4)3I solid electrolyte occurred at a constant rate during the cycling tests.To combat these effects, the cycle life of Li–S batteries was improved by increasing the amount of solid electrolyte in the cathode.

Consistency Research of Negative Electrode Pasting for MH/Ni High Power Battery

It is discovered that the consistency of negative electrode is one of the main influences on battery performance, since the main raw material in negative electrode is metal hydride powder, ingredients, particle distribution and density of the powder could influence the pasting consistency in some aspects.With the study of MH powder characteristics, through the modification of the coating die, the consistency of negative electrode is improved efficiently.

Electrochemical Properties and Crystal Structure of Rare Earth AB_(3.5)-Type Alloy as Negative Electrode Material in MH-Ni Battery

The electrochemical characteristics and crystal structure of metal hydride electrode of AB_(3.5)-type alloy was studied. The electrochemical properties of the metal hydride electrode were investigated at room temperature and -30 ℃. The partial substitution of Ni by Al element causes an expansion of the lattice cell and increases the specific capacity and rate discharge ability of the alloy.

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。

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。

基于翻转课堂的混合式教学质量提高的探索与实践——以“镍氢电池及材料”课程为例

“镍氢电池及材料”课程是新能源材料与器件专业的一门理论和实践性都很强的专业课程,因其知识点较多且枯燥,学生很难理解课本理论知识,想要激发学生的学习兴趣和自主学习的能力较难。随着混合式教学模式(线上+线下)在“镍氢电池及材料”课程中的实施,翻转课堂得以实现。研究结果表明:这种教学方式提高了学生的学习积极性和主动性,教师的教学质量和教学效果也得到了一定的改善。

Metal phosphonate-derived cobalt/nickel phosphide@N-doped carbon hybrids as efficient bifunctional oxygen electrodes for Zn-air batteries

The exploration of efficient bifunctional electrocatalysts for oxygen reduction reaction and oxygen evolution reaction is pivotal for the development of rechargeable metal–air batteries.Transition metal phosphides are emerging as promising catalyst candidates because of their superb activity and low cost.Herein,a novel metal phosphonate-derived cobalt/nickel phosphide@N-doped carbon hybrid was developed by a carbothermal reduction of cobalt/nickel phosphonate hybrids with different Co/Ni molar ratios.The metal phosphonate derivation method achieved an intimately coupled interaction between metal phosphides and a heteroatom-doped carbon substrate.The resultant Co_(2)P/Ni_(3)P@NC-0.2 enables an impressive electrocatalytic oxygen reduction reaction activity,comparable with those of state-of-the-art Pt/C catalysts in terms of onset potential(0.88 V),4e‒selectivity,methanol tolerance,and long-term durability.Moreover,remarkable oxygen evolution reaction activity was also observed in alkaline conditions.The high activity is ascribed to the N-doping,abundant accessible catalytic active sites,and the synergistic effect among the components.This work not only describes a highefficiency electrocatalyst for both oxygen reduction reaction and oxygen evolution reaction,but also highlights the application of metal phosphonate hybrids in fabricating metal phosphides with tunable structures,which is of great significance in the energy conversion field.

Improving sulfur transformation of lean electrolyte lithium-sulfur battery using nickel nanoparticles encapsulated in N-doped carbon nanotubes

Efficient redox reactions of lean electrolyte lithium-sulfur(Li-S)batteries highly rely on rational catalyst design.Herein,we report an electrocatalyst based on N-doped carbon nanotubes(CNT)-encapsulated Ni nanoparticles(Ni@NCNT)as kinetics regulators for Li-S batteries to propel the polysulfide-involving multiphase transformation.Moreover,such a CNT-encapsulation strategy greatly prevents the aggregation of Ni nanoparticles and enables the extraordinary structural stability of the hybrid electrocatalyst,which guarantees its persistent catalytic activity on sulfur redox reactions.When used as a modified layer on a commercial separator,the Ni@NCNT interlayer contributes to stabilizing S cathode and Li anode by significantly retarding the shuttle effect.The corresponding batteries with a 3.5 mg cm^(−2)sulfur loading achieve the promising cycle stability with~85%capacity retention at the electrolyte/sulfur ratios of 5 and 3μL mg^(−1).Even at a high loading of 12.2 mg cm^(−2),the battery affords an areal capacity of 7.5 mA h cm^(−2).

电池废料中有价金属的回收工艺研究

废旧锂离子电池正极材料提锂后,废料需要进行深度处理,从而回收镍、钴和锰。试验采用酸浸工艺处理废料,利用硫酸对镍、钴和锰进行浸出。试验结果表明,原料质量为50 g,硫酸用量为80 g,水添加量为200 mL,浸出时间为60 min,浸出温度为80 ℃时,镍、钴和锰的酸浸效果良好,镍浸出率为99.48%,钴浸出率为99.43%,锰浸出率为89.24%。酸浸工艺可用于处理废料,实现镍、钴和锰的高效浸出,为镍、钴与锰的分离奠定基础,应用前景较好。