LiNi1/3Co1/3Mn1/3O2/AC混合超级电容器正负极容量配比研究

采用1 mol/L的LiBF4/AN(CH3CN)为电解液,对LiNi1/3Co1/3Mn1/3O2/AC体系混合超级电容器进行了电化学性能对比研究.通过优化正负极的容量配比,分别评价了对应的超级电容器的充放电性能、倍率性能和循环寿命.结果表明,在正负极容量配比为4:1时,该体系超级电容器的比能量为11 Wh/kg、比...     

LiNi1/3Co1/3Mn1/3O2粉体的类共沉淀制备及性能

在含有Li+、Co2+、Ni2+、Mn2+离子的混合溶液中加入（NH4）2CO3作沉淀剂,通过一步共沉淀反应得到含有四种金属离子的混合沉淀前驱体。前驱体经烘干,研磨后在不同温度（700～1 000 ℃）及不同时间（6～24 h）条件下进行烧结,即得到LiNi1/3Co1/3Mn1/3O2粉体。分别通过X射线衍射（XRD）、扫描电镜（SEM）及循环伏安（CV）、交流阻抗对制备粉体的微结构进行表征和对样品的电化学性能进行测试。结果表明:获得的LiNi1/3Co1/3Mn1/3O2粉体为-NaFeO2层状结构,颗粒分布均匀,放电比电容高,阻抗小。其中在900 ℃下烧结12 h所得的LiNi1/3Co1/3Mn1/3O2粉体电化学性能最优。当电压窗口在（0～1.4）Vvs.SCE、扫描速度为5 mVs-1、电解液为1 molL-1 Li2SO4溶液时,其比容量可达399.46 Fg-1;并且其阻抗也最小。     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的研究进展

层状结构的LiNi1/3Co1/3Mn1/3O2正极材料具有比容量高、循环性能优异、成本较低和对环境友好的特点.综述了锂离子电池LiNi1/3Co1/3Mn1/3O2正极材料最近几年的研究现状与进展,并对其晶体结构特征、合成方法、掺杂与包覆改性以及表面修饰进行了评述,提出了目前锂离子电池正极材料研究中存在的问题,并对它未来的发展趋势进行了展望.     

锂离子电池混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4电化学性能研究

采用湿法球磨制备了锂离子电池用混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4。通过X射线衍射(XRD)和扫描电镜(SEM)表征了材料的结构和形貌,采用恒流充放电测试、循环伏安测试(CV)和电化学阻抗谱测试(EIS)方法研究了混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4的电化学性能。结果表明：混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4的晶体结构完好,碳包覆的纳米LiFePO4颗粒较好地包覆在LiNi0.5Co0.2Mn0.3O2表面。含质量分数15% LiFePO4的混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4电化学性能优良,0.2C首次充放电比容量为181.40 mAh?g–1,首次充放电效率为90.79%;1.0C循环50次后放电比容量为169.89 mAh?g–1,容量保持率为97.80%;3.0C循环5次后的放电比容量为162.22 mAh?g–1,容量保持率仍有89.43%;60 ℃高温存储7 d后,容量保持率和容量恢复率分别为86.48%和97.32%。     

锂离子电池正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的合成及性能研究

采用辐照凝胶法制备了锂离子电池正极用LiNi1/3Co1/3Mn1/3O2粉体材料。采用XRD、SEM和电化学充放电测试对制备材料的结构和性能进行了表征。结果表明:900℃制得的样品具有较好的层状结构,结晶性适中,电化学性能优异:其首次放电容量高达184mA·h/g(2.80～4.50V,C/10),30次循环后的容量保持率为87.4%,表现出较好的充放电容量和循环性能,较之850,950℃煅烧样品具有最小的交流阻抗和直流阻抗。     

LiNi_(0.5)Mn_(1.5)O_4/Li_4Ti_5O_(12)电池体系的性能研究

采用高温固相法合成了锂离子电池用正极材料LiNi0.5Mn1.5O4和负极材料Li4Ti5O12。通过XRD和SEM分析,并借恒电流充放电和循环伏安法测试了LiNi0.5Mn1.5O4/Li4Ti5O12电池体系的电化学性能。结果表明:LiNi0.5Mn1.5O4和Li4Ti5O12均为尖晶石结构,LiNi0.5Mn1.5O4/Li4Ti5O12电池具有良好的充放电循环可逆性,以0.5C倍率充放电,首次放电比容量可达124.31mAh·g–1,充放电循环50次后,放电比容量在116mAh·g–1以上,容量保持率为93.32%。     

三氟乙酸离子液体/四氟硼酸螺环季铵盐混合电解液的超级电容性质研究

采用两步法合成功能化离子液体1-甲基-3-丁基咪唑三氟乙酸盐离子液体([Bmim][CF_3CO_2]),并将其与有机电解质四氟硼酸螺环季铵盐([(C_4H_8)_2N][BF_4])组成不同浓度配比的新型混合电解液。采用活性炭为电极,组装成超级电容器,通过循环伏安、恒流充放电、交流阻抗等方法对其电化学性能进行了研究。结果显示:混合电解液的浓度为2.06 mol/L时的性能最优,这种新型的混合电解液25℃时电导率为3.99×10~(–3) S/cm,电化学窗口可达2.7 V,内阻0.96?,经过1 000次充、放电循环后仍可保留98%的初始比电容,说明该混合电解液具有突出的电化学性能和巨大的市场应用潜力。     

锂离子电池正极材料LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2的合成及电化学性能

采用碳酸盐共沉淀法合成了Ni0.4Co0.2Mn0.4CO3前驱体,然后以Ni0.4Co0.2MnCO3和LiOH为原料,合成出了层状锂离子电池正极材料LiNi0.4Co0.2Mn0.4O2.通过XRD,SEM和电化学测试对LiN0.4Co0.2Mn0.4O2材料的结构、形貌及电化学性能进行了测试和表征.结果表明,800℃下烧结12 h所得到的样品,以0.2 c放电,其首次放电容量151 mAh·g-1,循环30次后容量为138 mAh·g-1,电化学性能好.     

NaOH活化制备超级电容器用活性炭球电极材料

以NaOH为活化剂、采用蔗糖水热法,制备超级电容器用高比表面积球形活性炭电极材料。采用标准N2吸附法、SEM和XRD对活性炭的结构进行表征,用恒流充放电测试其在1mol/L Et4NBF4/PC电解液中的电化学性能,并将其与日本商业电容炭YP17进行了比较。结果表明:ζ(NaOH∶活性炭)为5∶1、600℃活化1h制备的球形活性炭比表面积为3261m2/g,其比电容可达156F/g,远大于YP17(108F/g),大电流倍率性能突出。     

锂离子电池正极材料LiNi_(1-x)Co_xO_2的合成及性能

以硝酸盐为原料,用sol-gel法合成锂离子电池正极材料LiNi1-xCoxO2,采用XRD、SEM和电化学测试等方法对材料的物理化学性质以及电化学性能进行表征。结果表明,经过Co掺杂后,材料具有较高的初始放电比容量和较好循环性能。在750℃下合成的LiNi0.8Co0.2O2,在3.0~4.2 V 0.2 C下经恒电流充放电测试,其首次放电容量为170.40mAh.g–1,经过30次充放电循环后放电容量为149.86 mAh.g–1,可逆容量的保持率为89.95%。     

High‐Performance Olivine for Lithium Batteries: Effects of Ni/Co Doping on the Properties of LiFeαNiβCoγPO4 Cathodes

New high voltage and high capacity storage systems are needed to sustain the increasing energy demand set by the portable electronics and auto­motive fields. Due to their good electrochemical performance, lithium‐transition metal‐phosphates (LiMPO₄) seem to be very attractive as cathode materials for lithium secondary batteries. Here the synthesis and the characterization of five high voltage cathodes for lithium batteries, based on lithium–iron, lithium–nickel, lithium–cobalt phosphates are described. The effect of differing degrees of cobalt and nickel doping on structure, morphology, and the electrochemical properties of the different materials is thoroughly studied. Transition metal atoms in these materials are found to be vicariant within the olivine crystal structure; however, the lattice parameters and cell volume can be modulated by varying the nickel/cobalt ratio during the synthesis. High performance battery prototypes in terms of voltage (>4.0 V), specific capacity (125 mAh g^?1), specific energy (560 mWh g^?1), and cyclic life (>150 cycles) are also demonstrated.     

Proton exchange in Y-cut LiNbO3

In the present work, planar waveguides in Y-cut LiNbO₃ were obtained using modified proton exchange (PE) conditions of: PE and subsequent annealing (APE), PE in buffered melts (BMPE), APE followed by PE (APE+PE), and PE in vapours (VPE). Benzoic acid was used as the proton source in the PE, BMPE, and (APE+PE) experiments. Cinnamic acid was used for obtaining VPE-waveguides. The main aim was to prevent surface damage of Y-cut crystals due to the strains introduced by proton exchange. The investigations performed showed that the surface etching is probably due to lattice deformation anisotropy leading to higher strains in PE Y-cut samples. Most encouraging results were observed, when an optimized (APE+PE)-procedure was used for waveguide formation. This method is very attractive for the fast preparation of deep high-index and low-loss waveguides in Y-cut LiNbO₃. This procedure allows passive and active elements to be produced in one and the same Y-cut substrate of LiNbO₃. Similar preliminary results were obtained under VPE conditions.     

Synthesis and Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2 Cathode Material

LiNi_1/3Co_1/3Mn_1/3O₂ layer-structured compound was synthesized by the rheological phase reaction method. The structure and morphology of samples were characterized by x-ray diffraction and scanning electron microscopy. The particle size was distributed from 100 nm to 400 nm, depending on the synthesis temperature. The electrochemical properties of the samples were examined using a battery testing system. The results showed that the discharge specific capacities of the samples were strongly impacted by the synthesis temperature. The LiNi_1/3Co_1/3Mn_1/3O₂ synthesized at 850°C had a high initial discharge specific capacity (about 181 mA h/g at 0.1 C) and better electrochemical cycling performance compared to the other samples. (After 50 cycles, the discharge capacity was maintained at 170 mA h/g.) The reasons why the sample synthesized at 850°C showed outstanding electrochemical properties are also discussed.     

Synthesis and Surface Modification of LiCo1/3Ni1/3Mn1/3O2 for Lithium Battery Applications

In an attempt to prepare phase-pure LiCo_1/3Mn_1/3Ni_1/3O₂ compound, the sol–gel method with precursors containing different ratios of lithium and transition-metal ions such as Li:M = 1:1, 1.05:1, 1.10:1, 1.15:1, 1.20:1, and 1.25:1 has been deployed. Properties such as phase purity, perfect layeredness, good cation ordering, and acceptable charge–discharge behavior were observed only when LiCo_1/3Ni_1/3Mn_1/3O₂ was prepared using a Li:M ratio of 1.15:1.0, leading to the recommendation of this as the optimum precursor ratio to prepare active LiCo_1/3Ni_1/3Mn_1/3O₂ cathodes for batteries. Further, with a view to suppress the capacity fade behavior of native LiCo_1/3Mn_1/3Ni_1/3O₂ cathodes observed in high-voltage (4.6 V) regions, selected HF-scavenging metal oxide (Al₂O₃) or metal hydroxide [Al(OH)₃] was deployed as a surface modifier. Interestingly, LiCo_1/3Ni_1/3Mn_1/3O₂ cathode modified with Al(OH)₃ exhibited significantly improved electrochemical properties such as lower charge-transfer resistance (42 Ω), higher specific capacity (158 mAh/g), and excellent capacity retention (99%). This study demonstrates the superiority of Al(OH)₃ over Al₂O₃ in modifying the electrochemical properties of native LiCo_1/3Ni_1/3Mn_1/3O₂ cathodes, as desired for practical lithium battery applications.     

铅镁锰锑铌多元系压电陶瓷材料

采用先驱体法制备了Pb(Mg_(1/3)Nb_(2/3))_A(Mn_(1/3)Nb_2/3))_B(Mm_(1/3)Sb_(2/3))_CZr_DTi_EO_3(PMMSN)铅镁锰锑铌多元系中温压电陶瓷材料。从XRD图谱可以看出,先驱体法容易消除焦绿石相,得到单相钙钛矿材料。实验结果表明,先驱体法制成样品的烧成温度较低,压电和介电性能优良。1100℃烧结样品的性能参数:Qm为2060,k_p为0.55,ε_r为1200,d_(33)为293 pC/N,tgδ为0.45×10~(-2),可用于压电变压器、超声换能器和压电马达等功率型器件。     

Effect of Cr2O3 Coating on LiNi1/3Co1/3Mn1/3O2 as Cathode for Lithium-Ion Batteries

Cr₂O₃ was applied to modify the surface of LiNi_1/3Co_1/3Mn_1/3O₂ cathode material by a novel facile route. X-ray diffraction (XRD), scanning electron microscopy and x-ray photoelectron spectroscopy were used to characterize the structure, shape and composite of the obtained samples. Transmission electron microscope images clearly show that the uniform coating layer thicknesses are about 40 nm and 45 nm for 1 wt.% and 2 wt.% Cr₂O₃, respectively. At the high concentration (3 wt.%), the coating layer becomes heterogeneously distributed. After coating with 1 wt.%, 2 wt.%, and 3 wt.% Cr₂O₃, the initial specific discharge capacities decrease to 159.3 mAh g^?1, 156.4 mAh g^?1, and 152.7 mAh g^?1 at 0.1 C, respectively. Despite an increasing charge transfer resistance for the Cr₂O₃ coating, a better rate capability and cycling ability have been obtained. High temperature-XRD (HT-XRD) data indicate that the thermal stability of the electrode material has also been obviously improved, which is especially helpful for LiNi_1/3Co_1/3Mn_1/3O₂ used as the cathode of lithium power batteries.     

复合先驱体法制备铅镁锰锑铌系压电陶瓷材料

采用复合先驱体法制备了Pb(Mg1/3Nb2/3)a(Mn1/3Nb2/3)b(Mn1/3Sb2/3)cZrdTieO3(PMMSN) 铅镁锰锑铌多元系中温烧结压电陶瓷材料。结果表明,相同合成条件下,三组元复合先驱体法和六组元复合先驱体法比四组元复合先驱体法制得样品的钙钛矿相含量更高,在700℃即可得到单纯钙钛矿相材料,且复合先驱体法具有比单一先驱体法(二组元)工艺更加简单、成本更加低廉的优势。性能测试结果表明,三组元复合先驱体法制成样品的性能最佳。1 100℃烧结样品的性能参数:Qm为1 916,kp为0.56,r为1 349,d33为326,tg为0.43?02,可以满足超声马达和压电变压器等应用方面的要求。