钴掺杂氧化锰超级电容器的制备及其性能研究

用阴极还原二价锰和二价钴的方法在碳纤维上共沉积了Mn(OH)2和Co(OH)2前驱物,通过干燥和热处理过程制备了钴掺杂的氧化锰(CMO)。用扫描电子显微镜(SEM)、X射线衍射(XRD)、X光电子能谱(XPS)对CMO电极的形貌、结构和元素状态进行表征,用电化学工作站研究了电极材料的电化学性能。结果显示,由于钴原子进入氧化锰晶胞中,增加氧化锰的面间距,改善了氧化锰的电化学性能。     

CoO/石墨烯的制备及电化学性能研究

实验采用简单的水热法制备Co(OH)_2,将Co(OH)_2/氧化石墨烯逐层沉积在铜片上,在水平管式炉中热解得到CoO/石墨烯/Cu杂化电极。使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)以及透射电子显微镜(TEM)对材料形貌进行表征,XRD结果表明CoO结构是典型的立方体结构;SEM结果表明,CoO均匀分布在石墨烯表面。将2片电极对扣组成超级电容,使用循环伏安法以及恒流充放电法对其电化学性能进行测试,电化学性能研究结果表明,电容的比容量达到125.2 F/g;循环充放电3 000次后,电容量保持在原始电容量的93%以上,具有良好的电化学稳定性。     

柔性Yb(OH)3@Ni(OH)2/CC纳米复合电极材料的制备及性能研究

以柔性碳纤维(CC)作为基底材料,分别采用化学镀镍、电化学氧化和电化学沉积的方法制备出Yb(OH)₃复合Ni(OH)₂碳纤维纳米电极材料(Yb(OH)₃@Ni(OH)₂/CC)。以X射线衍射仪(XRD)测试材料的结构和组成成分;利用场发射扫描电子显微镜(FE-SEM)对材料的微观形貌进行表征;利用线性循环伏安法(CV)、交流阻抗法(EIS)、恒流充放电法(GCD)对材料的电化学性能进行测试研究。实验结果表明,当电流密度为10mA/cm²时,该复合材料的面积比电容高达1216mF/cm²;循环充放电1000次后的容量保持率为90%,比Ni(OH)₂/CC材料的容量保持率提高14%。     

电解法制备氢氧化钴的研究

本文对电解法制备氢氧化钴进行了研究。结果表明,当金属钴为阳极,阴极材料为钛网,电解温度为70℃左右,电解6小时,电流效率(μ_2)可为79.1％,收率以钴计算可达99.6％以上,氢氧化钴的耗电量在4.54KW-hr/kg左右。     

碳纸负载Co(OH)_2-Co纳米片的制备及其催化NaBH_4电氧化行为研究

通过电沉积和化学还原过程在碳纸表面负载Co(OH)_2-Co纳米片,制得氢氧化钴-钴@碳纸电极(Co(OH)_2-Co@CP),并将其用于催化NaBH_4的电氧化反应。利用SEM、TEM、XRD及XPS等物理表征手段对所制备电极的形貌、组成、元素价态等进行了分析,并用CV及CA等电化学方法研究了所制备电极在碱性溶液中对Na BH4的电氧化催化行为。结果表明,所制备电极对NaBH_4电氧化具有良好的催化活性。     

Co(CO3)0.35Cl0.20(OH)1.10纳米线的制备 及其超级电容器性能

通过简便的一步水热法成功制备出了Co(CO_3)_(0. 35)Cl_(0. 20)(OH)_(1.10)(Cobalt chloride carbonate hydroxide,CCCH)纳米线,并采用XRD、SEM等表征了CCCH的结构和形貌,其平均直径约为200 nm,长度大约为5μm。测定了CCCH纳米线电极的超级电容器性能,在1 A/g时,其比容量达到1536 F/g,即使在32 A/g的高电流密度下,比电容也能达到741 F/g。结果表明制得的CCCH纳米线具有良好的电化学性能,是一种有潜力的超级电容器电极材料。     

Ni(OH)_2/石墨烯/Co(OH)_2电极材料制备及其电容性能研究

将具有法拉第赝电容但导电性较差的材料与具有良好导电性的石墨烯结合是提高超级电容器电极材料电容性能的合理策略。以水热法制备的Ni(OH)_2/石墨烯复合材料与生长有Co(OH)_2的泡沫镍制得修饰电极。用循环伏安法(CV)、恒电流充放电(CP)和电化学阻抗(EIS)测试了其在6 mol/L KOH溶液中的电容行为。实验表明,片状六边形Ni(OH)_2插入薄膜状石墨烯片层间,Ni(OH)_2/石墨烯/Co(OH)_2电极材料有良好的电容性能,在电流密度为1 A/g时比电容量达到了294 F/g,能量密度为36.75 Wh/kg。充放电循环1 000圈后比电容值仍是初始电容的92.7%。     

纳米片层状氢氧化钴/泡沫镍复合材料的超级电容性能研究

本文在2.3 V电压、30 mA电流、120 s沉积时间条件下,采用控电位电沉积方法在泡沫镍基体上沉积Co(OH)_2制备了复合电极材料并研究了其超电容性能。结果表明:所获得的复合电极材料表面为纳米片层状Co(OH)_2,且保留了泡沫镍的三维网状结构。这一结构促进了电极活性物质与电解液之间的充分接触以及离子在电极体相中的吸附与脱附,使复合材料具有优异的超电容特性,比电容值高达975.8 F/g(50 mV/s),内阻仅为0.74Ω。     

温度对电沉积氢氧化镍电化学性能的影响

在0.1mol/L的Ni(NO3)2溶液中,采用电化学沉积法制备出适用于锌镍微电池的氢氧化镍电极,研究了电沉积温度对Ni(OH)2电极的电化学循环伏安性能以及充放电性能的影响。测试结果表明,电沉积方法制备的Ni(OH)2电极适合于微电池的制作。30°C下电沉积制备的Ni(OH)2电极具有优异的电化学性能,其质子扩散系数为7.71×10-12cm2/s,放电比容量为1285μAh/cm2,利用率达91.4%。     

Ni(OH)_2/C复合电极材料的合成及超电容性能研究

采用溶剂热法合成Ni(OH)_2/C复合电极材料,研究C对复合电极材料电化学性能的影响。测试结果表明,产物为片状不规则外观,且Ni(OH)_2未发生晶型结构改变,Ni(OH)_2/C复合电极材料表现出较好的电化学性能,首次放电比容量达到185.0 F·g~(-1)。当测试电流密度为0.5A·g~(-1)时,充放电循环200次后的比容量保持率为92.5%,说明复合材料具有较好的循环稳定性。     

Structure and electrochemical properties of nickel hydroxide electrodes with cobalt additives

In this article,cobalt additives are introduced into nickel hydroxide electrodes by two incorporation methods—co-precipitated cobalt hydroxide during the nickel hydroxide synthesis or post-added CoO with nickel hydroxide. The results of X-ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, and charge–discharge tests indicate that (i) the diffraction peaks show a decrease in intensity and increase in the half peak breadths for Ni(OH)₂ with co-precipitated cobalt hydroxide; (ii) the electrochemical activity of nickel hydroxide can be improved by both incorporated cobalt and the effects of post-added CoO are more notable; (iii) CoOOH derived from post-added CoO is not stable in the KOH electrolyte when the potential of the Ni(OH)₂ electrode is lowered and its reduction product may be inactive, thus results in an irreversible capacity loss of nickel-metal-hydride battery after over-discharge-state storage.     

氢氧化镍电极的修饰及电化学性能的研究

镍系列二次电池的正极活性物质Ni（OH）2的晶型和镍电极的制备工艺对电池的性能具有较大的影响。文章以镍-氢电池作为对象,着重研究作为电池正极的氢氧化镍电极。通过不同的方法制备电极的活性物质Ni（OH）2,以Co、Zn和稀土作为掺杂剂对电极进行修饰,并对不同掺杂方式构成的电池进行了测试。用金相显微镜来观察Ni（OH）2的外观、颗粒大小;通过恒电流放电曲线比较各电极的放电性能,并通过XRD谱图了解样品的晶型结构。电池性能测试结果表明：采用配位沉淀法制备的Ni（OH）2晶体为最佳;在添加剂方面,Zn、Co、Sm均对镍电极的电化学性能影响较大。     

Bi2O3 modified cobalt hydroxide as an electrode for alkaline batteries

Manganese dioxide electrode shows reversible charge storage capacity, if the charge-discharge process is limited to 0.3e⁻ exchange. Addition of small amount of Bi₂O₃ to manganese dioxide induces reversibility with an exchange of 2e⁻/Mn. Nickel hydroxide is known to reversibly exchange 1e⁻. In spite of isostructural relationship between the cobalt hydroxide, nickel hydroxide and manganese dioxide, cobalt hydroxide does not show any electrochemical activity. Bi₂O₃ modified cobalt hydroxide electrodes exchanges 0.3-0.5e⁻/Co during the charge discharge process. The oxidation-reduction process in cobalt hydroxide and Bi₂O₃ modified cobalt hydroxide electrodes were monitored using the PXRD patterns.     

Ca3(PO4)2 coating of spherical Ni(OH)2 cathode materials for Ni-MH batteries at elevated temperature

Calcium phosphate was used for surface modification of spherical nickel hydroxide to improve its high temperature performance at the first time due to its low cost. The Ca₃(PO₄)₂ and Co(OH)₂ coated nickel hydroxides were prepared by precipitation of Ca₃(PO₄)₂ on the surface of spherical nickel hydroxide, followed by precipitation of Co(OH)₂ on its surface. The optimum coating content of calcium was around 2% (atomic concentration) to obtain high discharge capacity both at 25 and 60 °C. It was shown that the discharge capacity of nickel hydroxide at higher temperatures was improved by coating of Ca₃(PO₄)₂ and cobalt hydroxide. The high temperature performances of the sealed AA-sized nickel-metal hydride (Ni-MH) batteries using Ca/Co coated nickel hydroxide as positive electrodes were carried out, showing much better than those using uncoated or only Co(OH)₂ coated nickel hydroxide electrodes. The charge acceptance of the battery using 2% Ca and 2% Co coated nickel hydroxide reached 81% at 60 °C, where the charge acceptances for uncoated and only Co(OH)₂ coated nickel hydroxide were only 42 and 48%, respectively. It has shown that the Ca/Co coating is an effective way to improve the high temperature performance of nickel hydroxide for nickel-metal hydride batteries. It is a promising cathode material of Ni-MH batteries for EV applications due to the cost.     

Structural modifications and electrochemical behaviour of the β(II)-Ni(OH)2/β(III)-NiOOH redox couple upon galvanostatic charging/discharging cycling

Among the various crystallographic phases of nickel hydroxide, the β-form is the most widely used as the active mass of the positive electrode of nickel-based secondary cells. However, the exact electrochemical and structural behaviour of the β(II)/β(III) redox system upon cycling and ageing remains to be clarified. This work reports the electrochemical behaviour under galvanostatic conditions of two non-doped Ni(OH)₂ samples having different initial crystallography and morphology. The evolution of these features is investigated as a function of the cycling conditions and more particularly as a function of the reduction state achieved on discharge. Electrodes cycled at the 1st discharge plateau show that charged/discharged active materials are very similar. However, when discharge is continued down to the so-called ‘second discharge plateau’, drastic changes are observed as an increase of the crystallisation degree and of the compactness of the Ni(OH)₂ powder. Some insights into the nickel electrode redox behaviour are given. It appears that the nickel electrode operates, upon charge, as a single-phase or as a mixed-phase system depending on the depth of discharge.     

Cyclic voltammetric studies of pasted nickel hydroxide electrode microencapsulated by cobalt

Spherical nickel hydroxide microencapsulated by cobalt has been used as the electrochemically active material in pasted-type nickel electrodes of rechargeable alkaline batteries. Cobalt coating on the surface of nickel hydroxide particles can be converted to CoOOH during charge. Well distributed CoOOH forms the conductive network on the surface of nickel hydroxide particles, thereby leading to higher utilization of active material. Cyclic voltammetric studies suggest that nickel hydroxide microencapsulated by cobalt has better reversibility of the Ni(OH)2/NiOOH redox couple, greater discharge capacity and higher oxygen evolution overpotential than nickel hydroxide with added cobalt metal powder as a conductor. The mechanism of the electrode reaction is still found to be controlled by proton diffusion, and the proton diffusion coefficient is 1. 2×10–9cm2s–1.     

Structure and electrochemical behaviors of a series of Co-B alloys

A series of Co_xB (x = 1, 2, 3) alloys were prepared by arc melting, the phase structure of the alloys were characterized by X-ray diffraction (XRD). The electrochemical experimental results demonstrated that the Co_xB (x = 1, 2, 3) series alloys showed excellent cycling stability, the capacity retention was 94.2%, 93.6% and 93.8% in the 100th cycle, respectively, as the cobalt content decreased. The CoB alloy electrode showed very good electrochemical reversibility in cyclic voltammetry (CV) curves, the oxidation and reduction peaks resembled the pure cobalt element powder electrode. The electrode mechanism was discussed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), using pure CoB alloy cast electrode. From the SEM, after first and second cycle, the surface became porous and pulverous; also, the oxidation state of Co changed through XPS, after second cycle, the Co of 0 oxidation state could not be found on the surface. Based on the experiment, a proper mechanism was proposed: on this condition, the discharge capacity may due to the Co(OH)₂/Co reaction, which happened on the porous surface as the boron dissolved when the cycle increased.     

稀土Nd~(3+)与Cu~(2+)掺杂非晶态纳米Ni(OH)_2材料的电化学性能

晶态氢氧化镍[Ni(OH)2]在碱性电解液中易发生相变,影响其电化学性能。文中采用微乳液快速冷冻共沉淀法制备Nd3+和Cu2+复合掺杂非晶态纳米Ni(OH)2粉体材料,并对其结构形貌及物理特性进行表征分析。结果表明,制备出的非晶态Ni(OH)2样品材料,微结构含有较多结晶水,物相近似球形,粒径大小在20—30nm。对样品电极材料的电化学性能测试发现,掺杂Nd3+和Cu2+的摩尔比为2∶1时,所制备的样品材料合成镍电极,并组装成MH-Ni模拟电池,在恒电流80mA/g下充电6h,40mA/g放电,终止电压为1.0V的充放电条件下,放电比容量高达348.0mA.h/g,放电中值电压为1.2723V,同时样品电极材料的氧化还原可逆性较好,电极过程的电化学阻抗较小。电化学性能优于目前MH-Ni生产应用的晶态β-Ni(OH)2电极材料。     

The effect of cobalt on the electrochemical performance of β-nickel hydroxide electrodes

Crystalline β-nickel hydroxide comprises of a periodic stacking of charge neutral nickel hydroxide layers. Translation or rotation of nickel hydroxide layers with respect to each other generates stacking faults while an intergrowth of one polymorphic modification in the other generates interstratification. These changes generate structural disorder within the sample and the phases are designated as β_bc (bc-badly crystalline) nickel hydroxide. The structure, composition and morphology of these phases differ significantly compared to highly ordered crystalline β-nickel hydroxide. Crystalline β-nickel hydroxide exchanges 0.3e/Ni whereas stacking faulted β-nickel hydroxide and β_bc-nickel hydroxide exchanges 0.8–0.9e/Ni. Inclusion of cobalt metal as a conducting additive during the electrode fabrication of pasted electrodes is expected to enhance the electrochemical performance of nickel hydroxide. In contrast to the literature reports, partial substitution of cobalt for graphite to highly ordered crystalline phase of β-nickel hydroxide does not show any improvement in their electrochemical activity. Stacking faulted β-nickel hydroxide, β_bc-nickel hydroxide and chemically substituted nickel hydroxide samples also does not show any enhancement in their reversible discharge capacity on inclusion of cobalt. This clearly demonstrates that the electrochemical activity is mainly dictated by the structural disorders at 25–30 °C.     

PVA基碱性聚合物电解质Ni(OH)2/AC超级电容器的电化学性能

Polyvinyl alcohol(PVA)-sodium polyacrylate(PAAS)-KOH-H₂O alkaline polymer electrolyte film with high ionic conductivity was prepared by a solution-casting method.Polymer Ni(OH)₂/activated carbon(AC) hybrid supercapacitors with different electrode active material mass ratios(positive to negative) were fabricated using this alkaline polymer electrolyte,nickel hydroxide positive electrodes,and AC negative electrodes.Galvanostatic charge/discharge and electrochemical impedance spectroscopy(EIS) methods were used to study the electrochemical performance of the capacitors,such as charge/discharge specific capacitance,rate charge/discharge ability,and charge/discharge cyclic stability.Experimental results showed that with the decreasing of active material mass ratio m(Ni(OH)₂)/m(AC),the charge/discharge specific capacitance increases,but the rate charge/discharge ability and the charge/discharge cyclic stability decrease.