锂离子电池正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的研究进展

锂离子电池正极材料Li Ni1/3Co1/3Mn1/3O2具有比商业化正极材料——LiCoO2更低廉的成本、更低的毒性、更好的热稳定性,近年来受到广大科研工作者的关注。主要介绍了Li Ni1/3Co1/3Mn1/3O2正极材料的合成改性方法及其近年来在电化学性能方面所取得的成果和进展,并简要概括了该材料结构和发展趋势。不断提高Li Ni1/3Co1/3Mn1/3O2正极材料的振实密度以及电化学性能特别是其在高倍率充放电条件下的循环性能将成为相关科研工作者的研究重点。     

镍钴锰三元正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2最新研究进展

为解决镍钴锰三元材料存在的首次充放电效率低、大倍率性能不够理想等问题,人们对这类材料进行掺杂和表面改性方面开展了大量的研究工作。综述了近年来锂离子电池镍钴锰三元正极材料的合成方法、掺杂以及表面修饰等方面的研究进展,并简要概述了该材料的发展趋势。     

纳米SnO_2可控合成及其对LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2电化学性能的影响

采用溶胶法制备Sn(OH)4胶体,以炭载体控制吸附胶体粒径,通过高温烧结制备炭载纳米Sn O2,并通过载体转移技术将纳米Sn O2转移到Li Ni1/3Co1/3Mn1/3O2正极材料表面,考察了合成工艺条件对纳米Sn O2及其前驱体粒径的影响,并对纳米Sn O2修饰的Li Ni1/3Co1/3Mn1/3O2正极材料进行分析。结果表明:在以十二烷基苯磺酸钠为表面活性剂、陈化12 h、添加炭载体的条件下可以有效控制Sn O2前驱体胶体的粒径;Sn O2负载在Li Ni1/3Co1/3Mn1/3O2表面,没有进入Li Ni1/3Co1/3Mn1/3O2材料的结构中,纳米Sn O2提高了Li Ni1/3Co1/3Mn1/3O2的电化学性能;在0.5C、1C、2C、5C下充放电,首次放电容量分别提高了3.75%、0.96%、6.41%、8.71%,1C倍率循环50次之后,容量保持率由71.35%提高至92.14%。     

锂离子电池正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2与电解液的相容性

研究LiNi1/3Co1/3Mn1/3O2正极材料在四种不同的电解液体系中(LiPF6/EC+DEC(1∶1)、LiPF6/EC+DMC(1∶1)、LiPF∶6/EC+EMC(1∶1)和LiPF∶6/EC+PC+DMC(1∶1∶1))的电化学性能,讨论了正极材料与电解液的相容性。结果表明在1 mol·L-1LiPF6/EC+PC+DMC(1∶1∶1)电解液体系中,2.8~4.6 V电压范围内,LiNi1/3Co1/3Mn1/3O2的电化学性能最好,其首次放电比容量可达202.17 mA·h·g-1,50次的容量保持率可达88.58%。     

Ph(Zn_(1/3)Nb_(2/3))_x(Fe_(1/2)Nb_(1/2))_(0.64-x)(Fe_(2/3)W_(1/3))_(0.36)O_3系陶瓷的介电性质和钙钛矿相的稳定化

本文研究了Ph（Zn_(1/3)Nb_(2/3)）_x（Fe_(1/2)Nb_(1/2)）_(0.64-x)（Fe_(2/3)W_(1/3)）_(0.36)O_3系陶瓷中PZN含量与焦录石相形成间的关系，以及少量添加剂对钙铁矿相的稳定和介电性能的影响。在该系中仅添加0．15wt％MnCO3就可制备100％钙铁矿型结构的陶瓷。文中报导了该系组成的相关系和介电性质。钙铁矿结构的陶瓷，介电常数高，电容温度系数较低。     

Effects of microstructure on the microwave dielectric properties of Ba(Co1/3Nb2/3)O3 and (1−x)Ba(Co1/3Nb2/3)O3–xBa(Zn1/3Nb2/3)O3 ceramics

Ba(Co_1/3Nb_2/3)O₃(BCN) has a 1:2 ordered hexagonal structure. A large amount of the liquid phase, which contains high concentrations of Ba and Nb ions was found in the BCN ceramics. Q-values of BCN increased with increasing sintering temperature; however, it significantly decreased when the sintering temperature exceeded 1400 °C. The presence of a large amount of liquid phase could be responsible for the decrease of the Q-value. For (1−x)Ba(Co_1/3Nb_2/3)O₃–xBa(Zn_1/3Nb_2/3)O₃ [(1−x)BCN–xBZN] ceramics, the 1:2 ordered hexagonal structure was observed in the specimens with x⩽0.3 and the BaNb₆O₁₆ second phase was found in the specimens with x⩾0.6. Grain growth, which is related to the BaNb₆O₁₆ second phase occurred in the specimens with x⩾0.5. In this work, the excellent microwave dielectric properties of τ_f=0.0 ppm/°C, ε_r=34.5 and Q×f=97,000 GHz were obtained for the 0.7BCN–0.3BZN ceramics sintered at 1400 °C for 20 h.     

以废旧锌锰干电池制备LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2及改性研究

采用干湿结合回收技术回收了废旧锌锰干电池中的锰,讨论了硝酸浓度对碳酸锰回收率的影响。将得到的碳酸锰作为锰源,采用溶胶凝胶法制备了三元正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2。通过沉积法使氢氧化铝胶体沉积在材料表面对三元正极材料进行表面包覆改性。而且对所得产品进行了XRD、TEM表征和电化学性能检测。结果表明,少量包覆不会改变材料的层状结构,材料首次放电比容量达到152 m A·h/g,且提高了循环性能,循环充放电100次后,放电比容量为117.3 m A·h/g。     

添加剂对Ba(Zn_(1/3)Nb_(2/3))O_3-Sr(Zn_(1/3)Nb_(2/3))O_3陶瓷介电性能的影响

研究了MnCO3,BaZrO3对 0 .35Ba(Zn1 /3Nb2 /3)O3(BZN) -0 .65Sr(Zn1 /3Nb2 /3)O3(SZN)陶瓷介电性能的影响。研究表明 :添加MnCO3,BaZrO3时 ,对陶瓷的烧结均起促进作用 ,增大介电常数。加入 1% (质量分数 )的MnCO3可使陶瓷具有较小的介质损耗 ,同时MnCO3对陶瓷的介电常数温度系数具有正向调整作用。加入BaZrO3后通过生成液相而减少了第二相Ba5Nb4O1 5,BaNb2 O6 的生成。所制备的 ( 0 .35BZN -0 .65SZN) 0 .1%MnCO3陶瓷的εr≈ 43.6,αε≈ -8× 10 - 6 /K ,tanδ =0 .6× 10 - 4 ,且烧结温度低于 130 0℃。     

La(Mg1/2Ti1/2)O3–La2/3TiO3 microwave dielectric ceramics

Structure and microwave dielectric properties were studied in the (1−x)La(Mg_1/2Ti_1/2)O₃–xLa_2/3TiO₃ system. Ceramics with this composition in the 0⩽x⩽0.5 range were processed from powders obtained by a citrate-based chemical route. Structure of these perovskite solid solutions changed from orthorhombic for x=0.1 and 0.3 to pseudocubic for x=0.5. Microwave and radio frequency measurements revealed increase in permittivity and temperature coefficient of the resonant frequency τ_f with increasing of La_2/3TiO₃ content. Close to zero τ_f value was found near to x=0.5 composition of (1−x)La(Mg_1/2Ti_1/2)O₃–x La_2/3TiO₃.     

(1-y)Ca1-xLa2x/3TiO3-yCa(Mg1/3Nb2/3)O3复合体系的微波介电性能

采用固相合成法制备了(1-y)Ca1-xLa2x/3TiO3-yCa(Mg1/3Nb2/3)O3系列微波介质陶瓷材料.研究了复合系统的微波介电性能和微观结构.研究结果表明在y=0.4～0.6范围内,体系形成了单一的钙钛矿结构.当复合体系组成为0.5Ca0.6La0.267TiO3-0.5Ca(Mg1/3·Nb2/3)O3时,在1 400℃下烧结保温4 h所制备的材料表现出良好的微波介电性能εr=55,Q×f=45 000 GHz(7.6 GHz下),τf=0.04×10-6/℃.     

(1-y)Ca1-xLa2x/3TiO3-yCa(Mg1/3Nb2/3)O3复合微波介质陶瓷的研究

采用固相合成法制备了 ( 1-y)Ca1 -xLa2x/ 3 TiO3 -yCa(Mg1 / 3 Nb2 / 3 )O3 系列微波介质陶瓷材料 ,研究了复合系统的微波介电性能、烧结性能和微观结构。研究结果表明 :在y =0 .4～ 0 .6范围内 ,体系形成了单一的钙钛矿结构 ;当复合体系组成 0 .5Ca0 .6La0 .2 67TiO3 -0 .5Ca(Mg1 / 3 Nb2 / 3 )O3 时 ,在 14 0 0℃下烧结保温 4小时所得到材料的微波介电性能最佳 ;εf=5 5 ,Q×f =45 0 0 0GHz( 7.6GHz下 ) ,τf=0 .0 4ppm/℃。     

添加剂对Ba(Zn1/3Nb2/3)O3-Sr(Zn1/3Nb2/3)O3陶瓷介电性能的影响

研究了MnCO3,BaZrO3对0.35Ba(Zn1/3Nb2/3)O3(BZN)-0.65Sr(Zn1/3Nb2/3)O3(SZN)陶瓷介电性能的影响.研究表明:添加MnCO3,BaZrO3时,对陶瓷的烧结均起促进作用,增大介电常数.加入1%(质量分数)的MnCO3可使陶瓷具有较小的介质损耗,同时MnCO3对陶瓷的介电常数温度系数具有正向调整作用.加入BaZrO3后通过生成液相而减少了第二相Ba5Nb4O15,BaNb2O6的生成.所制备的(0.35BZN0.65SZN)+0.1%MnCO3陶瓷的εr≈43.6,αe≈-8×10-6/K,tanδ＝0.6×10-4,且烧结温度低于1 300℃.     

Dielectric properties of (1−x)La(Mg1/2Ti1/2)O3–xSrTiO3 ceramics

Powders of (1−x)La(Mg_1/2Ti_1/2)O₃–xSrTiO₃ series have been prepared by a non-conventional chemical route based on the Pechini method. Homogeneous solid solutions allowed the sintering of dense and single-phase ceramics for the full composition range (0⩽x<1). Crystal structure of the ceramics was investigated by XRD and several compositional driven structural transformations were observed. The dielectric function of the ceramics was measured at radio, microwave and far infrared (FIR) frequency ranges to help clarifying the relationship between dielectric properties and structure. The FIR data were found to reflect clearly the sequence of structural modifications observed. In order to evaluate the importance of intrinsic mechanisms in the dielectric response at the GHz and MHz ranges, the reflectivity spectra were fit to the Berreman–Unterwald form of dielectric function. The fits showed that the lower frequency dielectric response seems to be dominated by lattice phonons. Microwave permittivity and temperature coefficient of the resonant frequency were found to obey a hyperbolic-type law.     

(1-x)Ba(Mg1/3Nb2/3)O3-xBaSnO3陶瓷的微波介电性能

用传统陶瓷制备方法制备了(1-x)Ba(Mg1/3Nb2/3)O3-xBaSnO3[0.0≤x≤0.3,(1-x)BMN-xBS]体系微波介质陶瓷,研究了该陶瓷的微观结构和微波介电性能.用X射线衍射仪研究陶瓷的晶体结构.用扫描电镜观察陶瓷的显微结构.用网络分析仪测试陶瓷的微波介电性能.结果表明:晶格常数c和a均随x值的增加而增加;晶格常数比(c/a)随x值的增加而减小.当x≥0.1时,1∶2有序衍射峰消失.陶瓷的平均晶粒尺寸在0.7～2 μm之间.随x值的增加,陶瓷的相对介电常数(εr)和谐振频率温度系数(τr)呈线性减小;品质因数与谐振频率的乘积(Qf)呈非线性变化.当x=0.15时,Qf达到最大值,为86 200 GHz.当x=0.3时,在此体系中可以获得τf接近零的微波介质陶瓷Ba(Sn0.3Mg0.233Nb0.467)O3,其微波介电性能如下:εr=26.1;Qf=42 500GHz;τr=4.3×10-6/℃.     

(1-x)Ca_(15/16)Sr_(1/16)TiO_3-xLi_(1/2)Nd_(1/2)TiO_3陶瓷的相组成、显微结构及微波介电性能

采用传统固相法合成了(1-x)Ca_(15/16)Sr_(1/16)TiO_3-xLi_(1/2)Nd_(1/2)TiO_3(CST-LNT)系列微波介质陶瓷材料,研究了该系列材料的物相组成、显微结构及微波介电性能。XRD分析结果表明所有样品均为钙钛矿结构,无二次相出现。随着Li_(1/2)Nd_(1/2)TiO_3的加入,陶瓷平均晶粒尺寸下降,表明Li_(1/2)Nd_(1/2)TiO_3会抑制晶粒生长。随着x的增加,介电常数下降,频率温度系数向负方向移动。当x=0.85时,1250℃保温4 h可以得到优良的微波介电性能:ε_r=125.4,Q×f=2230GHz,τ_f=+14.4 ppm/℃。     

Dielectric and piezoelectric properties of Pb(Sc1/2Nb1/2)O3–Pb(Ni1/3Nb2/3)O3–PbTiO3 ternary ceramic materials

The dielectric and electrical properties of xPb(Sc_1/2Nb_1/2)O₃–yPb(Ni_1/3Nb_2/3)O₃–zPbTiO₃ (PSNNT 100x/100y/100z) ternary ceramic materials near the morphotropic phase boundary (MPB) were investigated. The MPB follows on almost linear region between PSNNT 58/00/42 and PSNNT 00/68/32 of the binary systems. The maximum electromechanical coupling factor kp=70·7% was found at PSNNT 36/26/38, where ε₃₃^T/ε₀=3019 and Tc=210°C were obtained. These values are similar to those of the Pb(Sc_1/2Nb_1/2)O₃–Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ system and better than those of PZT.     

锂离子电池三元正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的制备方法及其改性研究进展

三元正极材料(LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2)具有较好的安全性能和循环性能,兼顾了其它二元电极材料的诸多优点,成为目前高性能锂离子电池正极材料的研究重点之一,其市场占有率已经超过40%。详细叙述了近年来国内外对三元正极材料的制备和改性所做的研究,着重介绍了其高温固相法、共沉淀法、溶胶-凝胶法等制备方法及掺杂、包覆改性方法对LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2电化学性能的影响,以及这些改性方法存在的问题。     

锂离子电池三元电极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的制备方法及其改性研究进展

三元正极材料(LiNi1/3Co1/3Mn1/3O2)具有较好的安全性能和循环性能,兼顾了其它二元电极材料的诸多优点,成为目前高性能锂离子电池正极材料的研究重点之一,其市场占有率已经超过40%。详细的叙述了近年来国内外对三元正极材料的制备和改性所做的研究,着重介绍了其高温固相法、共沉淀法、溶胶-凝胶法等制备方法及掺杂、包覆改性方法对LiNi1/3Co1/3Mn1/3O2电化学性能影响,以及这些改性方法存在的问题。     

Pb(Ni_(1/3)Nb_(2/3))O_3-Pb(Mg_(1/2)W_(1/2))O_3-PbTiO_3三元系低温烧成多层陶瓷电容器瓷料的研究

本文选择Pb(Ni_(1/3)Nb_(2/3))O_3-Pb(Mg_(1/2)W_(1/2))O_3-PbTiO_3三元系低温烧成独石电容器瓷料为研究对象.实验结果表明,一次合成工艺优于分别合成工艺.采用适当的配方,可获得900℃左右烧成ε～8000,tgδ0.01～0.025,-25℃～+85℃下△C/C<±45%,且其它性能亦良好的独石瓷料.升温速度的加快将导致介电性能的下降.微观结构研究结果表明,颗粒尺寸的增加和高介电常数晶体的增多将有利于ε的提高.获得了890℃～920℃下一次烧成该瓷料用的全银电报.     

(Bi_(1/2)Na_(1/2))TiO_3BaTiO_3系无铅压电陶瓷工艺的研究

详细探讨了在制备(Bi1/2Na1/2)TiO3 BaTiO3(abbr.BNBT)系无铅压电陶瓷的过程中,合成条件Ty和烧结温度Ts对材料压电介电性能的影响,确定了较好的制备BNBT系压电陶瓷的工艺条件,并且系统地研究了(1-x)·(Bi1/2Na1/2)TiO3 xBaTiO3(x=0 02、0 04、0 06、0 08、0 10)的性能。XRD结构分析发现系统的相界在x=0 06,此时d33等压电介电性能参数达到最佳值。