Electrochemical performance of nickel／metal hydride batteries under unconventional conditions and degradation analysis

The charge-discharge performance and cycle stability of D size Ni/MH batteries at -20℃, 25℃ and 55℃ were examined. The results show that the decline rate of Ni/MH battery discharge capacity at -20℃ and 55℃ are 12.1% and 13.6% ,and the average discharge voltage decreases by a value of 0.13V and 0.06V respectively,cycling stability declines obviously at various temperatures. The capacity degradation of Ni/MH batteries under low temperature is reversible, belonging to transient degradation and that of high and normal temperatures are not reversible, belonging to permanent degradation. Electrochemical impedance spectroscopy, scanning electron microscope and energy dispersive X-ray analyzer were introduced to study the main causes of cycling deterioration of Ni/MH batteries.     

Effect of surface modification of metal hydride electrode on performance of MH/Ni batteries

A novel method was applied to the surface modification of the metal hydride(MH)electrode of MH/Ni batteries.Both sides of the electrode were plated with a thin silver film about 0.1μm thick using vacuum evaporation plating technology,and the effect of the electrode on the performance of MH/Ni batteries was examined.It is found that the surface modification can enhance the electrode conductivity and decrease the battery ohimic resistance.After surface modification,the discharge capacity at 5C(7.5A)is increased by 212 mA.h and the discharge voltage is increased by 0.11 V,the resistance of the batteries is also decreased by 32%.The batteries with modified electrode exhibit satisfactory durability.The remaining capacity of the modified batteries is 89%of the initial capacity even after 500 cycles.The inner pressure of the batteries during overcharging is lowered and the charging efficiency of the batteries is improved.     

Degradation analysis of nickel／metal hydride battery and its electrodes materials

The results indicate that during charge and discharge, the expansion of Ni(OH)2 crystal, pulverization of MH alloy particles and falling off from current collector are identified as the main causes for deterioration of Ni/MH batteries. Meanwhile, the contact resistance of inner battery increases due to the deterioration of the negative and positive electrode, and these changes lead to increasing battery body temperature and damaging its electrode and separator. The fibre‘s expansion and hole‘s diminishment of battery’s separator after degradation will affect the electrochemical performance and cycle life of Ni/MH batteries.     

过渡金属硒化物在锂硫电池中的应用

锂硫电池因较高的理论比容量(1675 mAh g_^-1)和能量密度(2600 Wh kg_^-1)成为研究的热点。硫资源丰富,无毒和环境友好等优势也使锂硫电池成为最有前途的储能体系之一。然而,仍然有硫的导电性差、多硫化物在电极之间来回“穿梭”和硫与其还原产物密度差异等问题制约其应用化发展。相关研究表明,过渡金属硒化物具有良好的导电性。基于其极性特征,过渡金属硒化物可以加速氧化还原反应动力学,抑制穿梭效应,改善锂硫电池的电化学性能。本文主要综述了过渡金属硒化物在锂硫电池正极材料以及隔膜等方面的应用,并且对过渡金属硒化物在锂硫电池应用的未来研究方向和发展趋势提出展望。     

Gas atomization of Cu-modified AB5 metal hydride alloys

Gas atomization together with a hydrogen annealing process has been proposed as a method to achieve improved low-temperature performance of AB₅ alloy electrodes in Ni/MH batteries and restore the original cycle life which was sacrificed by the incorporation of copper in the alloy formula. While the gas atomization process reduces the lattice constant aspect ratio c/a of the Cu-containing alloys, the addition of a hydrogen annealing step recovers this property, although it is still inferior to the conventionally prepared annealed Cu-free alloy. This observation correlates very well with the cycle life performance. In addition to extending the cycle life of the Cu-containing metal hydride electrode, processing by gas atomization with additional hydrogen annealing improves high-rate, low-temperature, and charge retention performances for both Cu-free and Cu-containing AB₅ alloys. The degradation mechanisms of alloys made by different processes through cycling are also discussed.     

Compositional optimization of vanadium-free hypo-stoichiometric AB2 metal hydride alloy for Ni/MH battery application

In an effort to reduce raw material cost and improve the charge retention characteristic of nickel metal hydride batteries, the Ti, Zr, and Ni-contents in vanadium-free AB₂ metal hydride alloys were optimized according to their capacity, charge retention, activation, high-rate capability, low-temperature performance, and cycle stability. A multi-component hypo-stoichiometric AB₂ alloy with a composition of Ti₁₀Zr₂₇Cr₈Mn₁₅Co₅Ni₃₅ was identified and compared to vanadium-containing AB₂ metal hydride alloys. Vanadium-free alloys provided better charge retention performance but with a trade-off in cycle life. The gaseous and electrochemical storage properties were correlated to both the average composition and the stoichiometry of the main AB₂ phases.     

机械化学法强化废弃锂离子电池中钴和锂的浸出

以SiO2为助磨剂,采用机械化学法提高废弃锂离子电池中Co和Li的浸出率.实验结果表明,在SiO2与LiCoO2质量比为1:1、研磨转速为500 r/min及研磨时间为30 min的最优条件下,Co和Li在柠檬酸中的浸出率分别达到94.91％和97.22％.表征结果表明,通过机械化学研磨,LiCoO2形成新的活性表面,...     

Si/MgO composite anodes for Li-ion batteries

A Si/MgO composite anode material was prepared by a simple magnesium reduction process using silicon oxide and magnesium as starting reactants.The feasibility of this process is discussed from the thermodynamic viewpoint.The resultant composite material is mainly composed of Si and MgO components.MgO,acting as a buffer layer,can accommodate the large volume change of active Si during the charge/discharge process,thus the cycling stability is improved.Electrochemical tests demonstrate that the first charge and discharge capacities of the synthesized Si/MgO composite anode are ca.1380 and 1046 mAh g-1,respectively,with an initial coulomb efficiency of ca.76%.The magnesium reduction process provides a novel idea for the synthesis of Si-based anode materials.     

Improvement in the low-temperature performance of AB5 metal hydride alloys by Fe-addition

The structures and electrochemical properties of a series of annealed AB₅, La_10.5Ce_4.3Pr_0.5Nd_1.4Ni_64.3−xCo_5.0Mn_4.6Al_6.0Cu_3.2Zr_0.2Fe_x (x = 0.0, 0.5, 1.0, and 1.5), metal hydride alloys were studied for improvement in the low-temperature performance of nickel/metal hydride batteries. As the Fe-content in the alloy increases, the following was observed: lattice constant a first increases and then decreases; lattice constant c and c/a ratio increase; unit cell volume increases monotonically; the main AB₅ phase becomes hyper-stoichiometric containing no Zr and its Fe-content is close to the target composition; an additional AB₇ phase appears; maximum gaseous hydrogen storage, PCT plateau pressure, and hysteresis first increase and then decrease while the trend of reversible hydrogen storage is the opposite; enthalpy and entropy of hydride formation remain unchanged; electrochemical full capacity decreases while the high-rate dischargeability and surface reaction exchange current increase; and bulk hydrogen diffusion increases first and then decreases by very small amounts. The product of charge-transfer resistance and double-layer capacitance measured at −40 °C indicates an improvement in the surface catalysis with Fe-addition. In the sealed cell, the addition of Fe improves both the specific power and −10 °C low temperature performance, slightly reduces the charge retention, and first marginally improves and then deteriorates the cycle life performance.     

锂离子电池的工作原理与关键材料

锂离子电池具有能量密度高、自放电小和循环寿命长等优点,被广泛用于便携式电子设备和电动汽车等方面,不断推动着社会朝着智能化和清洁化方向发展.简要阐述了锂离子电池的发展历程和工作原理,从材料结构和储锂机制方面对正极材料和负极材料进行分类并综述其性能特点与研究现状,介绍了液态电解液中锂盐、溶剂、添加剂以及固态电解质在锂离子电...     

Effects of Mo additive on the structure and electrochemical properties of low-temperature AB5 metal hydride alloys

After an annealing treatment at 960 °C for 8 h, the molybdenum added into previously designed AB₅ alloys for −30 °C applications segregates into spheres with diameters between 1 and 10 μm. A secondary phase with Zr-to-other elements ratio of about 1-to-5, over- (AB₇), and under-stoichiometric (AB₄) phases were observed in most of the alloys regardless of Mo-content. As the Mo-content increases, the AB₇ phase disappears while the AB₄ phase grows in size and abundance. Regarding the gaseous absorption properties, a small amount of Mo (0.2 at.%) in the main phase reduces the plateau pressure and hydride heat of formation uniformly for all Mo-containing alloys. The reduction in main phase abundance causes a decrease in both the total and the reversible hydrogen storage capacities. In electrochemical testing, the addition of Mo decreases the discharge capacity, high-rate dischargeability, and hydrogen diffusion in the bulk. The influence of Mo-addition to general battery performance is very minor. However, the low-temperature AC impedance measured at −40 °C shows reduced charge transfer resistance and increased double layer capacitance in the Mo-containing alloys. Mo was found to assist the surface reaction at very low temperatures, and the effect is proportional to the amount of addition as noted by the increasing surface area and catalytic ability, which is similar to the case of AB₂ alloys.     

SnO2/Ni复合锂离子电池负极材料的制备及其电化学性能

采用机械球磨法将纳米SnO2和Ni粉末复合,作为锂离子电池负极材料。采用XRD、SEM、TEM和EDS分析球磨过程中材料结构和形貌的变化。对SnO2/Ni复合负极材料的首次库仑效率、循环稳定性及CV曲线等进行测试分析。结果表明:将复合粉末球磨适当时间后,SnO2和Ni可形成结合充分、颗粒尺寸细小、分布均匀的复合材料;SnO2和Ni的复合可有效提高SnO2的首次库仑效率和循环稳定性;SnO2/Ni复合负极材料的循环稳定性随球磨时间的延长而增加,但电极的首次库仑效率随球磨时间的延长呈先增加后下降的趋势;Ni的引入有效减小了SnO2在首次充放电循环过程中生成Li2O的不可逆反应程度,并在随后的循环过程中部分以Li-O化合物的形式进行可逆反应。     

金属有机框架衍生的Bi/C复合材料作为钠离子电池负极材料的研究

金属铋(Bi)用作钠离子电池的负极材料具有较高的理论比容量和较低的嵌钠电位,但是在钠离子嵌入和脱出的过程中容易发生较为严重的体积膨胀,从而导致循环性能较差。为改善金属Bi负极的循环性能,将其与具有多孔结构的碳复合是一种有效的改善手段。在过去几年中,金属有机框架(metal-organic frameworks,MOFs)作为一种合成前驱体被广泛应用于各种金属氧化物及多孔碳材料的合成中。合成了一种含铋的金属有机框架材料,并以其为前驱体,再经高温煅烧合成了多孔碳包覆的金属铋复合材料,该复合材料中的碳骨架及其丰富的孔结构能有效缓解Bi在钠离子脱嵌过程中的体积膨胀,从而提高其循环稳定性。     

锂离子电池含硫无机电极材料研究进展

锂离子电池含硫无机电极材料包括二元金属硫化物、硫氧化物、Chevrel相化合物、尖晶石硫化物、聚阴离子型磷硫化物等。综述了含硫无机材料作为锂离子电池电极材料的研究现状,展望其发展趋势,并指出聚阴离子型磷硫化物等新型材料的重大研究价值。     

Rare earth-Mg-Ni-based hydrogen storage alloys as negative electrode materials for Ni/MH batteries

This review is devoted to new rare earth-Mg-Ni-based (R-Mg-Ni-based) hydrogen storage alloys that have been developed over the last decade as the most promising next generation negative electrode materials for high energy and high power Ni/MH batteries. Preparation techniques, structural characteristics, gas-solid reactions and electrochemical performances of this system alloy are systematically summarized and discussed. The improvement in electrochemical properties and their degradation mechanisms are covered in detail. Optimized alloy compositions with high discharge capacities, good electrochemical kinetics and reasonable cycle lives are described as well. For their practical applications in Ni/MH batteries, however, it is essential to develop an industrial-scale homogeneous preparation technique, and a low-cost R-Mg-Ni-based electrode alloy (low-Co or Co-free) with high discharge capacity, long cycle life and good kinetics.     

新型负极添加剂对MH/Ni电池性能的影响

用过渡金属氧化物作为ＭＨ／Ｎｉ电池的负极添加剂,研究了它对ＭＨ／Ｎｉ电池容量、放电电压、电池内压和循环性能的影响。加人２％的新型负极添加剂,可以在保证电池容量不受影响的前提下,使ＭＨ／Ｎｉ电池的放电中值电压升高约２０ｎＶ,以１Ｃ倍率电流充电时的最大电池内压减少０．４ＭＰＡ,并显著提高电池循环性能。以１Ｃ倍率快速充放测试徨４００次时,其容量保持率在９０％以上,放电中值电压变１．２１６Ｖ。     

锂蓄电池正极材料LiV3O8的合成和充放电性能

采用一种液相反应的方法合成LiV3O8化合物 ,首先由NH3·H2 O ,LiOH与V2 O5反应合成含有Li和V的反应前驱产物 ,然后在 180℃的真空环境中进行干燥处理 ,最后将此物质在 5 80℃温度下煅烧成最终产物。采用热重分析试验分析了反应的机理。X射线衍射结果显示得到的物质与用传统合成方法得到的LiV3O8化合物的结构相比 ,在 (10 0 )方向上的衍射峰强度降低很多。在室温、恒电流为 3A/m2 条件下进行充放电试验 ,在 1.8～4.0V范围内 ,首次放电容量达到 2 30Ah/kg ,15周后仍能达到 2 10Ah/kg。     

纳米结构尖晶石型锂离子电池电极材料的研究进展

综述了近年来纳米结构尖晶石型锂离子电池电极材料（LiMn2O4、LiNi0.5Mn1.5O4和Li4Ti5O12）的研究进展,重点对纳米结构与电化学性能之间的关联性进行了总结和探讨,并对纳米结构电极材料的发展前景进行了展望。     

花状CuO和花状CuO/石墨烯复合材料的制备及其在锂离子电池中的应用(英文)

采用水热法合成了花状CuO和花状CuO/石墨烯复合材料。采用XRD、SEM、TEM、BET、TG对材料的结构、形貌及性能进行表征和分析。花状CuO由CuO的纳米片组成,平均直径为4.2μm,比表面积为12.6m2/g。与花状CuO相比,花状CuO/石墨烯复合材料具有更高的充放电容量和更优良的循环稳定性。在0.1C、1C倍率下,其放电容量分别为603mA·h/g、382mA·h/g;在1C倍率下,经过50次循环,其容量保持率高达95.5%。     

Preparation of LiNi1/3Co1/3Mn1/3O2 cathode materials from spent Li-ion batteries

A recycling process including separation of electrode materials by ultrasonic treatment, acid leaching, Fe-removing, precipitation of cobalt, nickel, manganese and lithium has been applied successfully to recycle spent lithium-ion batteries and to synthesize LiNi1/3Co1/3Mn1/3O2. When ultrasonic treatment with 2-nitroso-4-methylphenol（NMP） at 40 ℃ for 15 min, the electrode materials are separated completely. Above 99% of Co, Ni, Mn and Li, 95% of Fe in the separated electrodes are acid-leached in the optimized conditions of 2 mol/L H2SO4, 1：2 H2O2：H2SO4 （molar ratio）, 70 ℃, 1：10 initial S：L ratio, and l h. 99.5% of Fe and less than 1% of Co, Ni, Mn in the leaching solution can be removed in the conditions of initial pH value 2.0-2.5 adjusted by adding 18% Na2CO3, 90 ℃ and stirring time 3 h. After adjusted to be equal by adding NiSO4, COSO4 and MnSO4 solution, 97.1% of Ni, Co, Mn in the Fe-removing surplus leaching solution can be recovered as Ni1/3Co1/3Mn1/3（OH）2. 94.5% of Li in the surplus filtrate after the deposition of Co, Ni and Mn can be recovered as LiECO3. The LiNi1/3Co1/3Mnl/3O2, prepared from the recovered compounds, is found to have good characteristics of the layered structure and elecrtochemical performance.