Synthesis and characterization of Li<Subscript>1.3</Subscript>Al<Subscript>0.3</Subscript>Ti<Subscript>1.7</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>-coated LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> by wet chemical route

Li_1.3Al_0.3Ti_1.7(PO₄)₃-coated LiMn₂O₄ was prepared by wet chemical route. The phase, surface morphology, and electrochemical properties of the prepared powders were characterized by X-ray diffraction, scanning electron micrograph, and galvanostatic charge-discharge experiments. Li_1.3Al_0.3Ti_1.7(PO₄)₃-coated LiMn₂O₄ has similar X-ray diffraction patterns as LiMn₂O₄. The corner and border of Li_1.3Al_0.3Ti_1.7(PO₄)₃-coated LiMn₂O₄ particles are not as clear as the uncoated one. The two powders show similar values of lithium-ion diffusion coefficient. When cycled at room temperature and 55°C for 40 times at the charge-discharge rate of 0.2C, Li_1.3Al_0.3Ti_1.7(PO₄)₃-coated LiMn₂O₄ shows the capacity retentions of 98.2% and 93.9%, respectively, which are considerably higher than the values of 85.4% and 79.1% for the uncoated one. Both the capacity retention differences between Li_1.3Al_0.3Ti_1.7(PO₄)₃-coated LiMn₂O₄ and LiMn₂O₄ cycling at room temperature and 55°C become larger with the increase of charge-discharge rate. When the charge-discharge rate reaches 2C, the capacity retention of LATP-coated LiMn₂O₄ becomes 8.4% higher than the uncoated LiMn₂O₄ for room temperature cycling, and it becomes 11.1% higher than the latter when cycled at 55°C.     

添加剂Li_3PO_4对锂离子固体电解质Li_（1.3）Al_（0.3）Ti_（1.7）（PO_4）_3性能的影响

采用溶胶-凝胶法,添加不同比例的Li3PO4助熔剂,合成Li1.3Al0.3Ti1.7（PO4）3锂离子固体电解质烧结片,采用X射线衍射、扫描电子显微镜研究合成产物的结构与形貌,采用循环伏安及交流阻抗技术研究添加不同摩尔分数的Li1.3Al0.3Ti1.7（PO4）3固体电解质烧结片的结构、氧化-还原电位、离子电导率和活化能。结果表明：添加与未添加Li3PO4助熔剂的Li1.3Al0.3Ti1.7（PO4）3烧结片具有相似的X射线衍射结果。添加Li3PO4的Li1.3Al0.3Ti1.7（PO4）3烧结片的空隙率较小,更为致密。添加Li3PO4对Li1.3Al0.3Ti1.7（PO4）3的氧化-还原电位影响不大。在所有添加Li3PO4助熔剂的Li1.3Al0.3Ti1.7（PO4）3烧结片中,添加1%（摩尔分数）Li3PO4的烧结片具有最高的离子电导率6.15×10-4S/cm和最低的活化能0.3142eV。     

Synthesis and character of spinel LiMn2O4

1　INTRODUCTIONTheincreasingconcernsonportableelectricele mentsdemandmoreandmoreelectrochemicalener gy .Countriesallovertheworldhaveputlargequan tityofmanuallabors ,materialresourcesandfinancialresourcesonbasicresearchanddevelopmentonnewtypeofrechargeablebatteries[1,2 ] .However ,thisnewtypeofbatteriesisbasedonstudyinganddevel opingperfectperformanceofmaterials ,especiallyonmaterialsofthelithiumbatteries.LixMn2 O4 cathodematerialshavebeenwidelystudiedoverthelasttwodecadesasapotentialcand…     

以Mn3O4为前驱体制备尖晶石型LiMn2O4及其性能

采用改进的固相反应法合成了高性能的锂离子电池正极材料LiMn2O4。首先,以廉价的MnSO4为原料,通过水解氧化法制备纳米级Mn3O4前驱体;然后,将Mn3O4和Li2CO3混合均匀,在750℃固相反应20 h,得到尖晶石型LiMn2O4。用X射线衍射(XRD)和扫描电镜(SEM)对Mn3O4前驱体和LiMn2O4样品进行表征,用充放电测试和循环伏安技术对LiMn2O4样品进行电化学性能研究。结果表明:所制备的LiMn2O4具有完整的尖晶石型结构,且晶体粒子分布均匀。所制备的LiMn2O4材料在3.0~4.4 V之间,室温(25℃)下,在0.2C倍率下首次放电比容量为130.6 mA.h/g;在0.5C倍率下首次放电比容量为127.1 mA.h/g,30次循环后,容量仍有109.5 mA.h/g,且样品具有较好的高温性能。     

Preparation and electrochemical characteristics of CO3（PO4）2-coated LiNi0.8Co0.2O2 by solid-state reaction at room temperature

LiNi0.8Co0.2O2 particles were modified by Co3（PO4）2 coating. The effects of the Co3（PO4）2 coating on the structure and electrochemical properties of the LiNi0.8Co0.2O2 cathode material were investigated. The Co3（PO4）2 coating forms a thin layer on the surface of the LiNi0.8Co0.2O2 material and a solid solution by interacting with the LiNi0.8Co0.2O2 core material during calcination at 700℃ for 4 h. Charge-discharge experiment results show that the Co3（PO4）2 coating improves the cycling stability of the LiNi0.8Co0.2O2 cathode material. The capacity retention of the pristine LiNi0.8Co0.2O2 cathode after 50 cycles is 83.6%, whereas it is 91.7% in the case of the LiNi0.8Co0.2O2 cathode coated with 1 wt.% Co3（PO4）2. Storage tests of the 4.35 V charged electrode at 60℃ after a month show that the Co3（POg）2-coated sample exhibits good storage properties compared with the pristine sample.     

Li1.3Al0.3Ti1.7（PO4）3基锂离子导电材料的制备与表征

采用以聚乙烯醇为聚合剂的湿化学法合成Li1.3Al0.3Ti1.7(PO4)3(LATP)锂离子导电材料,以Li4P2O7(LP)为助烧剂制备LATP-xLP(x=0,0.01,0.03,0.05,摩尔分数)锂离子导电固体电解质材料。利用X射线衍射、扫描电子显微镜和交流阻抗技术分别对材料的相组成、微观组织和离子导电性进行表征。通过分析材料晶体结构和交流阻抗特性,对材料的导电机理进行研究。结果表明:LATP粉体和LATP-xLP陶瓷具有菱方晶系结构,空间群为R3-c,该晶体结构具有三维离子导电通道;添加LP助烧剂使陶瓷的烧结温度降低了150℃、电导率得到了提高。交流、直流导电特性测量得出LATP-0.03LP的离子导电性占总导电性的99.5%。     

Effects of sodium substitution on properties of LiMn2O4 cathode for lithium ion batteries

Na-doped Li1.05Mn2O4 cathodes were synthesized using a sol-gel process.The samples were characterized by X-ray diffractometry(XRD),cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and charge-discharge measurements. The results show that all the samples exhibit the same cubic spinel phase structure without impurity.The lattice constant and unit cell volume decrease with increasing the sodium dopant amount.As the molar ratio of sodium to manganese(x=n(Na)/n(Mn))increases from 0 to 0.03,the initial discharge capacity of the Li1.05Mn2O4 cathodes decreases from 119.2 to 107.9 mA·h/g,and the discharge capability at large current rate and the storage performance decline dramatically,while cycling performance at room temperature and 55℃are improved.The CV and EIS studies indicate that reversibility of Li1.05Mn2O4 cathodes decreases and the electrochemical impedance increases with increasing the sodium dopant amount.     

Electrochemical performances and structure characteristic of LiMn2O4-xYx（Y=F, Cl, Br） compounds

Spinel LiMn2 O4-x Yx (Y=F, Cl, Br) compounds were prepared by solid-state reaction and the electrochemically galvanostatic charge-discharge cycles were performed using as-prepared compounds as cathode material. The influence of halogens on their lattice constants and the relation of electrochemical properties and their lattice constants were investigated. It is concluded that when the lattice constants are smaller than that of LiMn2O4, the reversible capacity fade is suppressed and the initial capacity sacrifice is observed. When the content of fluorine is 0.05, the lattice constant of LiMn2O3.95 F0.05 is larger than that of LiMn2O4, the initial capacity is improved. An efficient method was found to control the lattice constants of LiMn2O4 through the addition of halogen, and to improve the electrochemical performance of LiMn2O4. The LiMn2O3.95 F0.05 shows excellent electrochemical charge-discharge performance, with high initial capacity of 143 mAh/g and nearly no capacity loss after 116 cycles.     

Preparation of modified LiMn2O4 by solid-state reaction

Modified lithium manganese oxides were prepared by solid-state reaction of LiMn2O4 and LiCoO2 as raw materials. A study was carried out by TG-DSC,XRD, DSC and electrochemical to analyse the reaction process and structural characterization of products. The results show that the LiMn2O4 reacts chemically with LiCoO2 at high temperature. All of Li and partial Co atoms can insert into the LiMn2O4 crystal lattice and a newly formed spinel phase-modified LiMn2O4 was obtained. The distribution of Co content is even in modified LiMN2O4 compound. The modified LiMn2O4 compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure LiMn2O4.     

高能球磨辅助固相法制备Zr掺杂的钛酸锂

采用改进的高温固相法合成Zr4+掺杂的Li4Ti5O12,研究了原位包覆技术、高能球磨和金属元素掺杂对其晶型、相结构、颗粒形貌以及电化学性能的影响。结果表明:改进后的高温固相法能有效阻止颗粒团聚、提升颗粒的均匀分散度;Zr4+掺杂能降低电极极化、提升锂离子扩散系数,从而改善电化学性能。所得Li4Ti4.95Zr0.05O12在0.5 C倍率下首次放电比容量达176 mAh·g-1,在40 C高倍率下仍达52 mAh·g-1。另探讨了不同离子半径的Zr4+和Ce4+对掺杂效果的影响,结果表明较小离子半径的元素掺杂效果较好。     

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。     

Surface modification of LiCo0. 05Mn1.95O4 cathode by coating with SiO2-TiO2 composite

1　INTRODUCTIONSincethefirstcommercializationbySonyCorpo rationintheearly 1990s ,thelithium ionbattery(LIB)hasbecomeamajorproducttodominatethemarketforsmallrechargeablebatteries .Further more ,Li ionbatteriesareexpectedtobeusedasalarge scaleenergystoragedeviceforelectricvehices(EV ) [1] .ThoughvarioustypesofcathodematerialssuchasLiCoO2 ,LiNiO2 ,LiMn2 O4 ,andsubstitutedtran sitionmetaloxidesarecurrentlyusedincommercial izedLi ionbatteries[2 ,3] ,LiCoO2 inthesecathodematerialsismost…     

锂离子电池负极材料Li_4Ti_5O_(12)的制备及电化学性能

采用嵌段聚合物型表面活性剂P123作为结构导向剂,利用溶胶-凝胶方法制备出纳米TiO2作为合成Li4Ti5O12锂离子电池负极材料的原料之一.然后采用湿法球磨辅助的固相反应合成方法,以丙酮作为球磨介质,制备出Li4Ti5O12锂离子电池负极材科,并对所制备的Li4Ti5O12电极材料进行扫描电镜SEM、透射电镜TEM、粉末X射线衍射(XRD)、循环伏安(CV)以及循环性能测试.电化学性能测试表明所制各出的锂离子电池负极材料Li4Ti5O12具有较高的放电比容量和优异的循环性能.在电流密度为16 mA/g时首次放电比容量为155 mAh/g,首次库仑效率为98.3%.300次循环结束时放电比容量仍可达150.8 mAh/g,约为首次放电比容量的97.3%,300次循环容量仅衰减了2.7%.     

Synthesis and electrochemical performances of spherical LiFePO4 cathode materials for Li-ion batteries

Spherical LiFePO4 and LiFePO4/C composite powders for lithium ion batteries were synthesized by a novel processing route of co-precipitation and subsequent calcinations in a nitrogen and hydrogen atmosphere. The precursors of LiFePO4, LiFePO4/C composite and the resultant products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and the electrochemical performances were investigated by galvanostatic charge and discharge tests. The precursors composed of amorphous Fe3(PO4)2·xH2O and crystalline Li3PO4 obtained in the co-precipitation processing have a sphere-like morphology. The spherical LiFePO4 derived from the calcinations of the precursor at 700 ℃ for 10 h in a reduction atmosphere shows a discharge capacity of 119 mAh·g -1 at the C/10 rate, while the LiFePO4/C composite with 10wt.% carbon addition exhibits a discharge capacity of 140 mAh·g -1.The electrochemical performances indicate that the LiFePO4/C composite has a higher specific capacity and a more stable cycling performance than the bare olivine LiFePO4 due to the carbon addition enhancing the electronic conductivity.     

Electrochemical performance of Al-substituted Li_3V_2(PO_4)_3 cathode materials synthesized by sol-gel method

The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 in the raw materials of Li3V2(PO4)3.The XRD analysis shows that the Al-substituted Li3V2(PO4)3 has the same monoclinic structure as the un-substituted Li3V2(PO4)3.The SEM images show that Al-substituted Li3V2(PO4)3 has regular and uniform particles.The electrochemical measurements show that Al-substitution can improve the rate capability of cathode materials.The Li3Al0.05V1.95(PO4)3 sample shows the best high-rate performance.The discharge capacity at 1C rate is 119 mA·h/g with 30th capacity retention rate about 92.97%.The electrode reaction reversibility and electronic conductivity are enhanced,and the charge transfer resistance decreases through Al-substitution.The improved electrochemical performances of Al-substituted Li3V2(PO4)3 cathode materials offer some favorable properties for their commercial application.     

Improving the electrochemical performance of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>/graphite batteries using LiF additive during fabrication

LiMn2O4/graphite batteries using LiF additive were fabricated and their electrochemical performance including discharge,cycling and storage performances were tested and compared with LiF-free LiMn2O4/graphite batteries.The LiMn2O4/graphite battery with LiF added shows better capacity (107.5 mAh/g),cycling performance (capacity retention ratio of 93% after 100 cycles),and capacity recovery ratio (98.1%) than the LiF-free battery.The improvement in electrochemical performance of the LiF-added LiMn2O4/graphite...     

二步煅烧法制备高振实密度钛酸锂负极材料

以Li2CO3和纳米TiO2为原料,通过二步煅烧固相反应法制备Li4Ti5O12负极材料。研究前驱体球磨以及球磨时间对合成Li4Ti5O12样品振实密度和电化学性能的影响。借助XRD、SEM、振实密度仪和充放电测试仪、电化学综合测试仪表征Li4Ti5O12材料的物理性能和电化学性能。结果表明:球磨工艺能够提高Li4Ti5O12的纯度,并有效提高其振实密度和电化学性能;球磨时间为2 h时,所得材料的振实密度达1.70 g/cm3,0.1C首次放电比容量为174 mA.h/g,5C放电比容量达124.2 mA.h/g。     

Synthesis and electrochemical performances of LiCoO2 recycled from the incisors bound of Li-ion batteries

A new LiCoO2 recovery technology for Li-ion batteries was studied in this paper. LiCoO2 was peeled from the Al foil with dimethyl acetamide (DMAC), and then polyvinylidene fluoride (PVDF) and carbon powders in the active material were eliminated by high tempera-1.00. The new LiCoO2 was obtained by calcining the mixture at 850℃ for 12 h in air. The structure and morphology of the recycled powders and resulting samples were studied by XRD and SEM techniques, respectively. The layered structure of LiCoO2 synthesized by adding Li2CO3 is the best, and it is found to have the best characteristics as a cathode material in terms of charge-discharge capacity and cycling mAh.g-1.     

合成温度对LiMn1.95Mg0．05O4结构与性能的影响

用柠檬酸辅助溶胶一凝胶法在不同温度下合成了LiMn1.95Mg0．05O4正极材料。用X射线衍射、充放电测试以及电化学阻抗谱分析技术研究了不同合成温度对LiMn1.95Mg0．05O4结构和电化学性能的影响。结果表明：合成温度对LiMn1.95Mg0．05O4正极材料的晶相结构、电化学性能有显著影响,LiMn1.95Mg0．05O4尖晶石相的生成和长大与其合成的温度有密切的关系,合成的最佳温度为750℃;在750℃条件下合成的LiMn1.95Mg0．05O4具有较高的电化学活性和较好的晶相结构;高温合成有利于提高LiMn1.95Mg0．05O4正极材料的放电容量,低温合成有利于提高其循环性能。     

Zr对Li1.3 Ti1.7Al0.3(PO4)3传导材料中Na/Li离子交换反应的影响

Li13Ti17Al0.3(PO4)3是具有Nasicon骨架的锂离子传导材料,其中的Li 很容易被溶液中的Na 置换.研究了在Li1.3Ti1.7Al0.3(PO4)3结构中掺入Zr来替代Ti,以提高Na/Li离子交换速度.结果表明:增加Zr元素比例可显著提高Li1.3Ti1.7-xZrxAl0.3(PO4)3材料中Na/Li离子交换反应速度.Li1.3Ti1.7-xZrxAl0.3(PO4)3材料中的Na/Li离子交换反应动力学过程可近似由JMAK方程描述.