熔融盐法合成高密度锂离子电池正极材料LiNi0.8Co0.2-xAlxO2

利用低共熔组成的0.38LiOH-0.62LiNO3混合锂盐体系,与高密度前驱体Ni0.8Co0.2-xAlx(OH)2(0≤x≤0.15)在低温下自混合,无需前期研磨和后续洗涤,直接制备出高密度Co-Al共掺杂的锂离子电池正极材料LiNi0.8Co0.2-xAlxO2(0≤x≤0.15)。X射线衍射分析结果表明,合成的LiNi0.8Co0.2-xAlxO2具有规整的层状α-NaFeO2结构。扫描电镜显示产物颗粒均匀,LiNi0.8Co0.15Al0.05O2的振实密度达2.97g·cm-3。电性能测试表明,在0.2C放电倍率和3.0～4.3V的电压范围内,LiNi0.8Co0.15Al0.05O2首次放电比容量达167.5mAh·g-1,且具有良好的循环性能。     

含铝富锂正极材料xLi_2MnO_3·(1-x)LiNi_(0.8)Co_(0.15)Al_(0.05)O_2的制备和电化学性能

通过溶胶-凝胶法合成了含铝富锂正极材料xLi2MnO3·(1-x)LiNi0.8Co0.15Al0.05O2,探讨了化学组分(x=0.5,0.6,0.7,摩尔分数)和煅烧温度(850,900,950℃)对材料形貌、结构和性能的影响。采用XRD、SEM和电池充放电测试仪对材料进行物理表征和电性能测试。结果表明:所制备的材料具有典型的α-NaFeO2层状结构。当x=0.6、煅烧温度为900℃时,所合成的材料具有较好的形貌和优良的电化学性能;在2.0~4.6 V、0.1C充放电条件下,0.6Li2MnO3·0.4Li Ni0.8Co0.15Al0.05O2的首次放电比容量可达229.9 mA·h/g,且首次库仑效率为80.0%;在0.5C倍率下循环100次后,其放电比容量仍为192.7 mA·h/g,容量保持率达83.8%,显示了优良的循环性能。此外,材料显示了良好的倍率性能,在2.0C倍率下,其放电比容量仍为173.1 mA·h/g。     

Al2O3包覆LiNi0.03Co0.05Mn1.92O4正极材料的制备及其电化学性能

以Al(NO3)3?9H2O为包覆原料,通过燃烧法制备得到LiNi0.03Co0.05Mn1.92O4@Al2O3正极材料。通过X射线衍射(XRD),场发射扫描电子显微镜(FESEM)和透射电镜(TEM)等表征手段对材料的结构和形貌进行分析,并通过恒电流充放电、循环伏安(CV)、交流阻抗(EIS)等测试分析材料的电化学性能。结果表明,Al2O3包覆没有改变LiNi0.03Co0.05Mn1.92O4的尖晶石型结构,包覆层厚度约10.6nm。LiNi0.03Co0.05Mn1.92O4@Al2O3正极材料电化学性能得到了明显改善,1 C和10 C倍率下初始放电比容量分别为119.9 mAh?g-1和106.3 mAh?g-1,充放电循环500次后容量保持率分别为88.4%和78.2%,而未包覆的LiNi0.03Co0.05Mn1.92O4在1 C和10 C倍率下初始放电比容量分别为121.2 mAh?g-1和104.0 mAh?g-1,500次循环后容量保持率分别为84.1%和67.6%。LiNi0.03Co0.05Mn1.92O4@Al2O3活化能为32.92 kJ?mol-1,而未包覆材料的活化能为36.24 kJ?mol-1,包覆有效降低了材料Li+扩散所需克服的能垒,提高了材料的电化学性能。     

锂离子电池正极材料LiNi0.5Co0.2Mn0.3O2的制备及电化学性能

采用液相共沉淀法和固相烧结法分别制备镍钴锰复合氢氧化物(Ni0.5Co0.2Mn0.3(OH)2)和LiNi0.5Co0.2Mn0.3O2正极材料。通过X射线衍射和电化学性能测试对所得样品的结构及电化学性能进行了表征。结果表明:LiNi0.5Co0.2Mn0.3O2具有很好的α-NaFeO2层状结构,以20 mA/g的电流密度在2.5～4.3 V的电压区间充放电时,最高首次放电比容量达175 mA.h/g,首次库伦效率在89%～90%之间。当首次放电比容量为160～170 mA.h/g时,30循环未见容量衰减。锂含量对其电化学性能影响的结果表明:锂含量(n(Li)/n(Ni+Co+Mn))在1.03～1.09的范围内,随着锂含量的增加,放电比容量略有减小,但循环性能、中值电压以及平台性能都得到提高;当锂含量超过1.09时,循环性能、中值电压以及平台性能开始降低。     

共沉淀法制备LiNi0.8Co0.1Mn0.1O2过程中加料速度对其性能的影响

采用共沉淀法制备Ni0.8Co0.1Mn0.1(OH)2前驱体,与LiOH.H2O混合后在氧气气氛中焙烧得到LiNi0.8Co0.1Mn0.1O2正极材料,探讨共沉淀反应过程中快速加料和慢速加料制度对前驱体形貌和LiNi0.8Co0.1Mn0.1O2正极材料性能的影响。通过X射线衍射(XRD)、扫描电镜(SEM)和电化学测试对样品进行表征。结果表明:慢速加料法减小了材料的粒径,合成了平均粒径在0.5μm左右的球形Ni0.8Co0.1Mn0.1(OH)2前驱体,且粒径分布比较集中;所合成LiNi0.8Co0.1-Mn0.1O2正极材料具有良好的层状结构,且无杂相存在;缓慢加料法得到的样品的电化学性能有很大提高,在0.1 C、0.5 C和1 C下首次放电比容量分别达到223.5、194.3和190.7 mA.h/g,循环30次后,容量保持率为80.09%、80.80%和85.84%。     

熔融盐法合成高密度锂离子电池正极材料LiNi0.8Co0.2-xTixO2

利用具有低共熔组成的LiOH-LiNO3混合锂盐体系,与高密度前驱体掺杂Co的Ni(OH)2,TiO2粉末混合,经3阶段温度烧结制备出高密度Co-Ti共掺杂的锂离子电池正极材料LiNi0.8Co0.2-xTixO2（0≤x≤0.1）。XRD分析表明,合成的LiNi0.8Co0.2-xTixO2具有规整的层状α-NaFeO2结构。LiNi0.8Co0.2-xTixO2颗粒均匀,平均粒度为1~5 μm,随掺Ti量的增加而减小,LiNi0.8Co0.15Ti 0.05O2的振实密度达3.17 g·cm-3。电性能测试表明,在0.2 C放电倍率和3.0~4.3 V的电压范围内,LiNi0.8Co0.15Ti0.05O2首次放电比容量达169 mAh·g-1,且具有良好的循环性能和高倍率放电性能。     

控制结晶法合成球形正极材料LiNi0.8Co0.2O2及其电化学性能

采用控制结晶法制备锂离子电池用高密度球形正极材料LiNi0.8Co0.2O2。对前驱体Ni0.8Co0.2(OH)2制备工艺进行优化,在金属盐溶液流速为8 mL/min,搅拌速率450 r/min,pH值为11.5,氨浓度20 g/L反应36 h的条件下,合成了振实密度为2.02 g/cm3的球形Ni0.8Co0.2(OH)2。并以Ni0.8Co0.2(OH)2为原料,与LiOH.H2O进行混合研磨进行高温烧结,考察烧结制度对合成材料LiNi0.8Co0.2O2电化学性能的影响。在Li/(Ni Co)配比为1.05、氧气流量为800 mL/min,750℃下烧结16 h所得材料LiNi0.8Co0.2O2电化学性能最优:在0.2 C,3.0~4.3 V的条件下,首次放电容量达到195.4 mA.h/g,循环50次后容量保持率达到89.2%。     

球形高电压LiNi0.5Mn1.5O4的制备及其电化学性能

以化学共沉淀法制备的球形Ni0.25Mn0.75CO3为前驱体合成高电压正极材料LiNi0.5Mn1.5O4,探讨用前驱体与Li2CO3直接反应和用前驱体分解后的氧化物与Li2CO3反应两种工艺路线对LiNi0.5Mn1.5O4形貌和电化学性能的影响。用扫描电镜(SEM)和X射线衍射(XRD)对Ni0.25Mn0.75CO3前驱体和LiNi0.5Mn1.5O4样品进行表征,用充放电测试和循环伏安法对LiNi0.5Mn1.5O4样品进行电化学性能研究。结果表明:两种方法合成的LiNi0.5Mn1.5O4均具有尖晶石型结构。但以前驱体Ni0.25Mn0.75CO3直接与Li2CO3反应合成的LiNi0.5Mn1.5O4的一次粒子颗粒较大,形貌较差,性能也较差;而以前驱体分解后的氧化物与Li2CO3反应合成的LiNi0.5Mn1.5O4的形貌及性能均较好。在3.0~4.9 V的电压范围内,1C倍率下电池的放电比容量达到136.3 mA.h/g,循环100次仍有126.5 mA.h/g,且材料具有较好的倍率性能;5C倍率下的首次放电比容量高达120.7 mA.h/g。     

层状LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2正极材料的多元掺杂改性

采用共沉淀法制备锂离子电池掺杂型层状LiNi1/3Co1/3Mn1/3-xMxO2(M=Mg、Al、Cr)正极材料。采用X射线衍射、扫描电镜、充放电实验和交流阻抗实验对LiNi1/3Co1/3Mn1/3-xMxO2正极材料的结构、形貌、电化学性能以及动力学参数进行表征。结果表明:当掺杂量x=0.05时,Mg2+、Al3+掺杂的正极材料在2.8～4.3V、0.1C下的首次放电比容量分别为139.2、151.6mA·h/g,20次循环后的容量保持率分别为98.8%和96.7%;掺杂Mg2+或Al3+均能提高LiNi1/3Co1/3Mn1/3O2的交换电流密度和锂离子扩散系数。结合实验结果和掺杂离子的离子半径和化学稳定性,解释了掺杂离子在LiNi1/3Co1/3Mn1/3O2晶格中的占位及其在充放电过程中的作用。     

快速共沉淀过程pH值对Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_2及LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2性能的影响

采用快速共沉淀法制备Ni0.8Co0.1Mn0.1(OH)2前驱体,利用前驱体与LiOH.H2O的高温固相反应得到锂离子电池层状正极材料LiNi0.8Co0.1Mn0.1O2,探讨pH值对材料结构和电化学性能的影响。通过X射线衍射(XRD)、扫描电镜(SEM)和电化学测试对合成样品进行表征。结果表明,pH值为11.00~12.00时,合成的Ni0.8Co0.1Mn0.1(OH)2前驱体均无杂相;pH值为11.50时,合成的前驱体制备出的正极材料具有良好的电化学性能,0.1C倍率下首次放电比容量为192.4 mA.h/g;经过40次循环,容量保持率为91.56%。     

X-ray diffraction study of Ba0.985Na0.015Ti0.985Nb0.015O3, Ba0.6Na0.4Ti0.6Nb0.4O3 and Ba0.3Na0.7Ti0.3Nb0.7O3 compositions

The Ba_0.985Na_0.015Ti_0.985Nb_0.015O₃, Ba_0.6Na_0.4Ti_0.6Nb_0.4O₃ and Ba_0.3Na_0.7Ti_0.3Nb_0.7O₃ compositions of the (1 − x) BaTiO₃–xNaNbO₃ (BTNNx) system have been studied by X-ray diffraction and by measurements of dielectric properties. The specimens with composition BTNN (x = 0.015, 0.40 and 0.70) have been refined by the JANA program from X-ray powder diffraction data. Ceramic samples with composition (1 − x) BaTiO₃ + xNaNbO₃ (where x = 0.015, 0.40 and 0.70) were prepared by calcinations from appropriate mixture of BaCO₃, TiO₂, Na₂CO₃ and Nb₂O₅. The calcined powder was sintered at temperature range 1200–1400 °C. As the composition x increased from 0.015 (and 0.70), the ferroelectric ceramics (x = 0.015, FE) with tetragonal phase changed to the ferroelectric relaxors (RFE, x = 0.40). RFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to 180 K) due to a frustration between RFE and FE state. These ceramics present the classical ferroelectric character when 0 ≤ x < 0.075 and 0.55 < x ≤ 1 and relaxor character when 0.075 ≤ x ≤ 0.55.     

Magnetic, electrical and plastic properties of Fe76Nb2Si13B9, Fe75Ag1Nb2Si13B9 and Fe75Cu1Nb2Si13B9 amorphous alloys

Influence of 1 h annealing in vacuum on magnetic, electrical and plastic properties of Fe₇₆Nb₂Si₁₃B₉, Fe₇₅Ag₁Nb₂Si₁₃B₉ and Fe₇₅Cu₁Nb₂Si₁₃B₉ melt spun ribbons were carefully investigated. It was shown that in all cases soft magnetic properties can be significantly enhanced by applying 1-h annealing at characteristic temperatures T_op. This optimization annealing causes that permeability increases more than 15-times and magnetic losses (tangent of loss angle) achieves a minimum in relation to the as quenched state. Using structural examinations (X-ray and HRTEM) it was shown that for the Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy the optimized microstructure corresponds to a nanocrystalline αFe(Si) phase whereas in other alloys to a relaxed amorphous phase free of iron nanograins. As a consequence of this fact the Fe₇₆Nb₂Si₁₃B₉ and Fe₇₅Ag₁Nb₂Si₁₃B₉ alloys show higher plasticity in comparison to the nanocrystalline Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy. Temperatures of the first stage of crystallization, and related diffusion parameters were determined using measurements of resistivity versus temperature with different heating rates.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y₆CoBi₂ [a=0.8312(1) nm, c=0.4144(1) nm], Ho₆CoBi₂ [a=0.8246(2) nm, c=0.4095(1) nm], and Tm₆CoBi₂ [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr₆CoAs₂-type structure (space group P6b2m No. 189). The Zr₆CoAs₂-type structure is a superstructure of the Fe₂P-type structure.     

Zur Kenntnis von RbBa3Ca4Cu3V7O28

Single crystals of RbBa₃Ca₄Cu₃V₇O₂₈ were prepared above the melting point of the reaction mixture. It crystallizes with hexagonal symmetry, space group C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ is the second member of a new structure type of the copper-oxovanadates. Ba²⁺ shows an unusual 12-fold coordination. The two calcium positions are coordinated by trigonal prisms and octahedra respectively. The copper coordination is characterized by a stretched square pyramid. The Cu²⁺ ions are outside the centre nearly in plane of the pyramids.

Zusammenfassung

Einkristalle von RbBa₃Ca₄Cu₃V₇O₂₈ wurden oberhalb des Schmelzpunktes der Reaktionsmischung erhalten. Die Verbindung kristallisiert hexagonal, Raumgruppe C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ ist das zweite Beispiel für einen neuen Strukturtyp der Kupfer-Oxovanadate, mit 12-fach koordinierten Ba²⁺ -Ionen. Die zwei Calciumpositionen sind trigonal prismatisch bzw. oktaedrisch koordiniert. Die Koordination der Cu²⁺-Ionen ist durch eine gestreckte Pyramide charakterisiert. Cu²⁺ ist auβerhalb des Polyederzentrums nahezu in der quadratischen Fläche der Pyramide angeordnet.     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

电弧喷涂制备Fe65Cr20Mo7B3.5SiMn1.5W3涂层

在Q235低碳钢板上利用电弧喷涂工艺进行喷涂,以制得Fe65Cr20Mo7B3.5SiMn1.5W3涂层。喷涂材料为自行配制的丝材,按照35%的填充率将配好的粉填充到U型不锈钢外皮中,经过多道拉拔、挤压工艺制成Φ2mm的粉芯丝材。采用X射线衍射仪、扫描电镜、能谱分析仪、透射电镜对涂层的物相和组织形貌及成分进行了表征;采用差示扫描量热仪、显微硬度仪等设备对涂层的热稳定性及显微硬度进行了检测和分析。试验结果表明:涂层组织形貌呈典型的层状组织结构,由变形良好的带状粒子相互搭接堆积而成。涂层含有50.63%的非晶相,同时含有纳米级的晶相。涂层组织均匀、结构致密、孔隙率低,并且涂层硬度高达1040.5HV0.3,属硬质涂层,具有良好的热稳定性。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.