镍氢动力电池正极材料的研究

为了研究镍氢动力电池正极材料氢氧化镍,收集目前常用的镍氢动力电池用正极材料——普通型及覆钴型氢氧化镍,制备独有技术产品钙镁掺杂型氢氧化镍。通过对该3大类产品进行高温大电流性能的测试表明,适用于镍氢动力电池的氢氧化镍正极材料为覆钴型及钙镁掺杂型氢氧化镍。再考察不同覆钴量的覆钴型氢氧化镍及不同配比的钙镁型氢氧化镍,对覆钴量及钙镁掺杂量进行研究,得出主要用于镍氢动力电池的氢氧化镍产品为覆钴量为Co3.5%的覆钴型氢氧化镍及Ca2Mg0.5、Ca1.5Mg0.2、Ca1Mg0.3等3种成分的钙镁型氢氧化镍。     

表面包覆法合成的LiN0.8Co0.2O2材料的结构表征

LiNi0.8Co0.2O2是锂离子电池界公认的最有希望取代商业化正极材料LiCoO2的新型正极材料之一.本文所研究的复合正极材料LiNi0.8Co0.2O2是由细小的晶粒构成的球形颗粒,单一相,属于R3m空间群.对复合材料LiNi0.8Co0.2O2的Co-K和Ni-K的XANES分析可知,在600～850℃范围温度对于钴元素的影响不明显,而对于镍元素的影响比较显著,随着Ni-K边位置向高能量移动LiNi0.8Co0.2O2正极材料的放电容量升高.复合材料LiNi0.8Co0.2O2和LiNiO2的Ni-K边XANES相似,表明少量钴的引入对晶体结构的改变不是太多,但是峰的强度较高和峰的位置向高能量移动,表明钴Co对Ni的局域结构进行了调制.     

锂离子电池正极材料的研究进展

综述了近年来发展起来的一些锂离子电池正极材料 ,主要包括嵌锂的层状LixMO2 结构和尖晶石型LixM2 O4 结构的过渡金属氧化物 (M =Co、Ni、Mn、Cr等 )。重点介绍了锂钴氧化物、锂镍氧化物、锂锰氧化物的性能、制备、结构以及改性方法等 ,并对纳米电极材料和其它正极材料的发展情况作了简介     

锂离子电池正极材料Li[Ni_(0.92)Co_(0.04)Mn_(0.04)]O_2的合成新方法

采用溶胶-凝胶法在球形Ni(OH)2颗粒表面包覆钴、锰氧化物,合成了核壳结构的镍钴锰酸锂复合正极材料Li[Ni0.92Co0.04Mn0.04]O2。用X射线衍射、扫描电镜、恒电流充放电测试等方法对材料的结构、表观形貌及电化学性能进行了表征。结果表明,与镍酸锂材料相比,该镍酸锂复合正极材料表现出了较高的比容量,较好的循环稳定性及更好的安全性。     

纳米Co(OH)2的制备与电化学性能的研究

采用湿化学法合成了纳米Co(OH)2。并运用XRD、TEM等方法对反应产物进行了观察分析,结果表明得到的为六方片状的β-Co(OH)2,粒径在20-40nm之间。将该纳米β-Co(OH)2添加到镍正极中,电池测试结果表明,纳米β-Co(OH)2在电解质溶液中具有高的反应活性,能均匀地分散在镍正极中。与金属钴相比,能显著地提高镍电极中活性物质Ni(OH)2的利用率。     

激光熔覆制备抗冲蚀磨损镍基复合涂层的研究进展

冲蚀磨损是材料在流体或含固体颗粒流体的冲击作用下造成的表面磨损现象,在传统材料表面熔覆粉末可以有效改善其表面性能,抑制材料损伤速度,降低制造成本.采用激光熔覆制备的涂层具有结合强度高、对基材的稀释率低和热影响程度小等优点,用于解决恶劣环境下服役零件的冲蚀磨损问题,具有很好的应用前景.熔覆材料主要包括铁基、钴基、镍基三个体系.其中,铁基涂层抗磨性好、成本低,但涂层易产生裂纹缺陷,自溶性、抗氧化性差;钴基涂层耐磨耐蚀性好,但是价格昂贵;镍基涂层抗高温氧化性和耐磨耐蚀性好,价格适宜,综合起来优势明显,应用前景广阔.国内外很多研究人员通过调整镍基合金粉末的成分和激光熔覆的工艺参数改善涂层的性能,如向镍粉中加入硬质陶瓷颗粒或者合适的元素等提高镍基复合涂层的性能.主要硬质颗粒包括WC、Al2 O3、SiC、TiC等.一些学者通过加入镍铝金属间化合物来提高涂层的耐蚀性能;一些学者向涂层中加入稀土元素以生成稳定的化合物;一些学者研究工艺参数对涂层性能的影响.此外,还有一些学者通过在渣浆泵、抽油泵、水轮机等零件上制备镍基涂层,显著提升工件的耐磨耐蚀性能.本文综述了激光熔覆镍基复合涂层的研究进展,指出了目前研究存在的问题,并对未来的研究方向进行了展望,为镍基复合涂层的深入研究和在冲蚀磨损工况条件下的推广应用提供参考.     

锂离子电池富镍正极基础科学问题:晶粒形态及组装方式调控

晶粒辐射状组装的富镍正极具有较常规无序多晶更优的断裂韧性和Li+扩散速率，是快充长寿命锂离子电池理想的正极材料。近年来，部分研究者报道了系列富镍正极晶粒形态及组装方式调控研究进展，所开发的辐射状富镍正极性能优异，代表着全球顶尖水平，且相关技术应用于韩国电池巨头LG化学。然而，高度辐射状富镍正极材料的合成在国内尚处于起步阶段，且尚无合成辐射状富镍正极所需晶粒形态及组装方式调控的系统阐述。本文首先介绍富镍正极晶粒形态及组装方式调控的必要性；再综述了晶粒辐射状富镍正极所需前驱体沉淀结晶与其受控锂化的研究进展，并对沉淀及高温煅烧结晶调控晶粒形态及组装方式所涉及机制进行了分析，以期为国内相关专业人员开发高端富镍正极材料提供参考。     

镀钴泡沫镍基板界面机理研究

研究了泡沫镍镀钴镍电极的初期化成行为,发现在电池端电压0.2V附近出现一个充电电压平台,1.0V附近出现第二个充电电压平台,而纯泡沫镍做基板的镍电极无此现象.循环伏安和XRD测试验证了两个电压平台对应的反应是Co氧化为Co(OH)2和Co(OH)2氧化为CoOOH反应.EPMA线扫描显示,镍电极化成后基板表面钴元素呈梯度分布.结果表明,泡沫镍表面的金属钴通过电化学溶解沉淀机理,在基板附近生成梯度分布的CoOOH.     

用AIR-C2H2原子吸收光谱法测定镉镍电池正极浸渍液中钴含量

本文主要简述与运用AIR-C2H2原子吸收光谱法进行镉镍电池正极浸渍液中钴含量的测定，介绍了钴最佳测定条件及呈良好线性范围的浓度。同时对样品消化处理条件，在测定中样品的干扰因素进行了综合考虑，该方法具有很好的灵敏度，很好的重复性，干扰小，同时具有方法步骤简单，操作容易掌握等特点，对样品钴含量的测定，其相对标准偏差均小于1.0%（n=6），标准加入回收率均在97.0%～102.0%(n=5）范围内，结果表明，运用AIR-C2H2原子吸收光谱法测定镉镍电池正极浸渍液中钴含量的分析，达到了实验室分析质量控制的要求，完全适用于镉镍电池正极浸渍液中钴含量的控制分析和样品系统分析。     

层状锰酸锂正极材料的掺杂改性及性能

采用溶胶-凝胶法制备层状LiMnO2的正极材料，并对其进行不同比例的过渡元素钴镍镧铈掺杂改性。用XRD以及SEM对其进行物相和表面形貌的分析，同时用锂离子电池模具装配电池以及进行恒电流充放电、循环伏安等电化学测试，分析了掺杂元素对其电化学性能的影响。XRD分析结果表明所合成的锰酸锂材料呈斜方晶系，SEM形貌显示产物为明显的层状结构，循环充放电测试结果表明掺杂2％Ni2％Co6％Ce的层状锰酸锂正极材料的初次放电比容量为161．8mAh／g，循环稳定性较好：而掺杂了6％Co4％La的层状锰酸锂正极材料的初次放电容量为111．5mAh／g，表现了很好的电化学性能。     

A simple route to electrophoretic deposition of transition metal-coated nickel oxide films for electrochemical capacitors

Nickel hydroxide films coated with transition metals such as nickel and cobalt were fabricated directly by a one-step electrophoretic deposition (EPD) in the presence of charging additives (transition metal salts). A nickel hydroxide particle with a weakly charged surface in an isopropanol solution was found to be detrimental to EPD and dispersion. When a small amount of charging additive was added to the suspension, the adsorption of dissolved metal ions on the nickel hydroxide resulted in a more positively charged particle surface, facilitating EPD and dispersion. When nickel hydroxide particles migrated to the negative electrode during the EPD process, the metal ions adsorbed on the particle were reduced electrochemically to form a metal layer. The as-deposited nickel hydroxide film converted to nickel oxide following heat treatment at 300 °C. Our results revealed that nickel oxide films coated with nickel and cobalt showed better capacitive behavior than the bare film. The improved capacitive behavior was attributed to the co-deposition of transition metals, which provided additional active sites on the nickel oxide surface for the electrochemical reaction to occur.     

钴掺杂纳米花瓣状氢氧化镍的制备及其电化学性能研究

采用水热法制备了钴掺杂的纳米花瓣状Ni(OH)2,讨论了钴掺杂量对产物形貌、结构和电化学性能的影响。结果表明,不同钴摩尔分数掺杂的样品都呈现α/β混合相花瓣微球,其比表面积均在280m2/g以上,远高于普通球形氢氧化镍(5~10m2/g)。电化学性能测试表明,钴添加剂显著提高了氢氧化镍高倍率放电容量和循环稳定性能,1.0C倍率时钴摩尔分数10%的样品放电容量可达430.1mAh/g(以纯氢氧化镍计),接近-αNi(OH)2的理论容量(480mAh/g),3.0C倍率时其放电容量(367.1mAh/g)仅比0.2C时的放电容量(406.9mAh/g)衰减9.8%。     

纳米级氢氧化镍和钴对镍电极性能的影响

通过充放电曲线和交流阻抗谱的测定探讨了纳米级氢氧化镍和氢氧化镍表面包复CoOOH以及镍箔上电镀钴层对氢氧化镍粉末压制的镍电极性能的影响。结果表明．纳米级氢氧化镍有较快的活化能力，CoOOH包Ni(OH)2则有较高的放电容量，而比例适当的纳米复合镍电极才有更好的电化学性能。氢氧化镍表面包复CoOOH可改善镍电极的充放电性能；镍箔上镀钴可大大降低电极过程的电荷转移电阻；钴含量大于3％后．虽然活化速度有所下降，但是大电流充放电时，镍电极活性物的利用率更高，放电容量更大。纳米级Ni(OH)2含量大于30%后，镍电极的活化速度不仅未能加快，反而略有减慢，而且容量也降低。     

Novel tunable hierarchical Ni-Co hydroxide and oxide assembled from two-wheeled units

A novel hierarchical Ni-Co hydroxide assembled from two-wheeled units was successfully synthesized via a simple, hydrothermal method through the reaction of nickel salt, cobalt salt and sodium hydroxide, and with a chelating agent (EDA) to control the precipitation rate. The as-synthesized materials were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), atomic absorption spectrophotometer (AAS) and thermogravimetric analysis (TG). The Ni(2+)/Co(2+) molar ratio R in the initial solution plays an important role to control the morphology of the hierarchical Ni-Co hydroxide. The influence of the EDA concentration, reaction temperature and NaOH concentration on the formation of the hierarchical Ni-Co hydroxide was also investigated. The formation mechanism of the hierarchical Ni-Co hydroxide assembled by two-wheeled units was proposed. A Ni-Co oxide with a similar structure was obtained by calcination of the as-prepared Ni-Co hydroxide.     

基于钴活化的空心玻璃微珠表面化学镀镍工艺研究

提出了利用钴对玻璃微珠表面进行活化的化学镀镍新工艺。玻璃微珠表面在六氨合钴(Ⅱ)溶液中对六氨合钴(Ⅱ)离子进行吸附,镀液中次亚磷酸根离子将六氨合钴(Ⅱ)离子还原成单质钴作为催化活性基底材料分布在玻璃微珠表面。通过扫描电镜、X射线能量色散谱仪和X射线衍射分析表明,利用该工艺可在玻璃微珠表面形成均匀光滑、包覆完整的非晶态镍磷镀层,同时对活化机理进行了分析研究。     

Optimization of Residual Stresses in Laser-Mixed WC(Co,Ni) Coatings

Strength of Materials - A ternary mixture of tungsten carbide (WC), cobalt (Co), and nickel (Ni) powders is prepared to form ceramic-metal composite coatings employed for laser cladding of 40Cr...     

Synthesis of WC hard materials using coated powders

Nickel and cobalt were used as binder materials for tungsten carbide powders (WC) hard materials. Ni and Co binder were added individually to the WC powder by two different methods namely, mechanical mixing and chemical electroless coating. In this study WC powders of grain sizes 0.3–1.0 μm were electroless coated with either nickel or cobalt. The loading of either Ni or Co coating was 13 wt.%. The electroless-coating method conditions of both Ni and Co on WC powders are described. The coated powders were cold compacted and sintered in vacuum at different sintering temperatures. For comparison, identical materials compositions were prepared by mixing the powders constituents mechanically, compacted and sintered under the same conditions.The prepared powders and sintered materials were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM). The results revealed that coated WC materials have smaller values of porosity and more homogeneous microstructure while other properties, such as transverse rupture strength, and hardness exhibit greater values than those produced using mixing elemental powders. It is possible to outline the benefits of coated powder approach in the following: high homogeneity and better distribution of binder materials within WC hard materials, higher density and good interfacial bonding, capability of using fine powders, and possibility of using small alloying and/or reinforcement additions in a more uniform manner.     

Compatibility studies of carbon fibres with nickel and cobalt

Techniques have been evolved to study the compatibility of single carbon fibres coated with nickel or cobalt, and the results have been shown to be applicable to bulk composites. Carbon fibres undergo structural recrystallisation in contact with the nickel or cobalt matrix by a dissolution/diffusion/reprecipitation mechanism. The effective activation energy for this recrystallisation process approximates that for carbon diffusion in nickel or cobalt.     

Synthesis of high-density nickel cobalt aluminum hydroxide by continuous coprecipitation method

Spherical nickel cobalt aluminum hydroxide (Ni(0.80)Co(0.15)Al(0.05)-hydroxide, NCA) was prepared by a continuous coprecipitation method. A new design of the Al solution and the feeding method was applied, which enabled to prevent rapid precipitation of Al(OH)(3) and to obtain spherical NCA with large enough particle size and high density. The active material (LiNi(0.80)Co(0.15)Al(0.05)O(2) or LNCA) prepared from it showed higher tap-density than that made from NCA prepared by general processes, and homogeneity of Al-distribution was also improved. It is expected that the electrode density of lithium ion batteries adopting LNCA could be improved with the new process proposed in this study.