Li2MnSiO4/C复合正极材料的合成及电化学性能

采用溶胶-凝胶法合成了Li2MnSiO4/C复合正极材料,并用TG-DTA,XRD和电化学性能测试对材料进行了表征.前驱体的TG-DTA曲线表明,合成Li2MnSiO4时烧结温度应高于500℃.XRD测试表明Li2MnSiO4具有正交结构,对应Pmn21空间群.将Li2MnSiO4/C组装成扣式电池进行电化学测试的结果表明,600℃烧结10h所得样品性能最好,首次放电比容量达到124.2mAh·g-1,为理论比容量的74.5%;循环30次后放电比容量为71.5mAh·g-1.     

Y(Ⅲ)/Mg(Ⅱ)复合掺杂非晶态氢氧化镍材料的电化学性能

采用微乳液化学共沉淀法制备出稀土Y(Ⅲ)与Mg(Ⅱ)复合掺杂非晶态氢氧化镍粉体材料。应用XRD、SAED、SEM及Raman测试样品材料的表观形貌及微结构特征,同时研究样品材料电极的电化学性能。结果表明:复合掺杂Y(Ⅲ)/Mg(Ⅱ)的非晶态氢氧化镍粉体微结构缺陷较多,无序性增强,呈不规则的类球形;材料粉体作为MH-Ni电池正极活性物质,在充放电过程中电化学阻抗较小,在以0.2C充放电,终止电压为1.0V的制度下,其放电比容量高达到364.75mAh·g-1,同时放电中值电压较高并稳定于1.276V,1C下其放电比容量可达348.82mAh·g-1,充放电循环50次容量保持率为91.87%,显示出良好的较大倍率放电性能和循环可逆性能。     

球形Li_4Ti_5O_(12)/C复合材料的制备及其性能研究

以TiCl4和导电碳黑为原料,通过外凝胶法制备出掺碳球形前驱体,再通过一定的热处理后制备出了锂离子电池球形Li4Ti5O12/C复合负极材料。采用XRD、SEM、比表面及电化学性能测试等分析手段表明,掺碳抑制了Li4Ti5O12晶粒的生长,增大了比表面积,提高了材料的反应动力学性能;掺碳后Li4Ti5O12的振实密度有所降低,但仍明显高于采用传统固相反应法和溶胶-凝胶法制备的非球形产品,掺5%碳的Li4Ti5O12振实密度可达1.71g/cm3;当充放电倍率为1.0C时,在1～3V之间充放电,其首次放电比容量高达144.2mAh·g-1,经过100次充放电循环后,其放电比容量仍有118.2mAh·g-1。     

丙烯酸络合法制备锂离子电池负极材料ZnMn2O4

采用丙烯酸络合溶胶-凝胶法合成出锂离子电池用ZnMn2O4负极材料,并用TG-DTA,XRD,SEM和电化学性能测试对材料进行了表征。结果表明,在焙烧温度达到800℃,焙烧5h时能够形成单一四方相尖晶石结构的ZnMn2O4粉体,结晶良好;络合剂丙烯酸与金属离子摩尔比显著影响微观形貌,1:1时层片状结构发育完善;组装成扣式电池进行电化学测试的结果表明,丙烯酸:金属离子=1:1的样品具有较好的电化学性能,首次放电比容量达到992.9mAh·g-1,为理论比容量的98.5%,循环60次后放电比容量为308.4mAh·g-1。     

电沉积制备锡钴碳复合负极材料的结构与性能

采用电沉积法把Sn、Co原子沉积在硬碳颗粒上得到Sn-Co-C复合负极材料,然后球磨。XRD分析表明复合粉体由Sn、Co2C、CoSn2和C组成。电子探针测试表明试样中Sn、Co、C原子分数分别为2.9145%,0.6921%,95.3879%。SEM观察显示,锡钴粒子尺寸为50～100nm,沉积在片状的硬碳颗粒上。试样与锂片组成模拟电池,首次放电比容量为551.5mAh/g,充电比容量为309.4mAh/g。循环50次后放电比容量仍保持在319.6mAh/g,充电比容量保持在281.6mAh/g。交流阻抗测试表明,在第一次放电后形成了固体电解质层膜,但循环一次后消失。     

Zn^2＋掺杂对锂离子电池正极材料LiFePO4性能的影响

以Zn(NO4)2·6H2O为Zn源,蔗糖为C源,对LiFePO4进行了Fe位掺杂和包覆研究.用XRD、交流阻抗方法和恒流充放电研究了材料的结构和电化学性能.结果表明:包覆掺杂后的材料具有橄榄石型晶体结构.从LiFePO4、LiZn0.01Fe0.09PO4到LiZn0.01Fe0.99PO4/C其电荷转移阻抗逐渐减小,材料的可逆性能逐渐增强.掺杂后的材料初始容量和循环性能都得到明显的改善,在0.1C的倍率下,LiFePO4、LiZn0.01Fe0.99PO4和LiZn0.041Fe0.99PO4/C首次放电容量分别为93.1mAh·g-1、130.4mAh·g-1和159.2 mAh·g-1.放电倍率提高到0.5C时,LiZn0.01Fe0.99PO4/C首次放电容量仍有137.3 mAh·g-1,其后的70次循环容量衰减仅4.3%.     

LiFePO4／C复合正极材料的制备及其电化学性能研究

采用高温固相碳热还原法（CTR，Carbothermal Reduction）合成了LiFePO4／C复合正极材料。采用XRD，SEM以及BET等方法对产物进行表征。结果表明，所得LiFeP04／C材料有着单一的橄榄石型晶体结构。750℃下制备产物的BET比表面积为39．7002m^2／g。利用恒流充放电，循环伏安法（CV），电化学阻抗谱（EIS）等电化学手段研究了LiFePO4／C材料的电化学性质。结果表明：750℃下制备的LiFePO4／C复合材料在25℃工作温度下，有着优异的循环稳定性和大倍率充放电性能，使用850ma／g（5C）的电流密度对电池充放电90次后，电池放电比容量仍能保持11lmAh／g。在55℃工作温度下1C充放电倍率时，首次和第90次循环的放电比容量分别为14513mAh／g和142．9mAh／g。     

Li[Li0.2Ni0.15Mn0.55Co0.1-xCrx]O2-yCly富锂正极材料的合成及电化学性能研究

采用溶胶-凝胶法合成富锂正极材料,900℃煅烧12 h得到产物Li[Li0.2Ni0.15Mn0.55Co0.1-xCrx]O2-yCly。X射线衍射光谱(XRD)测试表明,材料均具有层状α-NaFeO2结构;扫描电镜(SEM)观察材料颗粒均匀,粒径达到纳米范围;充放电测试显示,Cl-、Cr3+共掺材料在2~4.8 V电压范围及0.1 C倍率下,20℃时,首次放电比容量达到239.8 mAh·g-1,首次库伦效率为81.2%;55℃时,首次放电比容量和首次库伦效率分别为308.3 mAh·g-1和92.7%。并且40个循环之后在1 C倍率下,材料在20和55℃时放电比容量仍分别达到173.5和207.7 mAh·g-1。     

锂离子电池正极材料LiFePO4掺碳纳米管的性能研究

以Li2CO3、FeSO4·7H2O、(NH4)2HPO4和Na2EDTA为原料,掺杂碳纳米管采用水热法合成了锂离子电池正极材料LiFePO4.研究了表面活性剂和碳纳米管对产物形貌和电化学性能的影响.结果表明:LiFePO4/MWCNTs样品属于橄榄石结构,在0.1C、3.0～4.3V条件下的首次放电比容量为145 mAh·g--,第20次循环的比容量为144.3 mAh·g-1.     

氮掺杂及PEG包覆对CNT/S材料储锂性能的影响

以硫代氨基脲为氮源,用高温退火法对碳纳米管实现氮掺杂,利用PEG对掺氮复合材料(NCNT/S)进行外包覆。采用X射线衍射仪(XRD),扫描电子显微镜(SEM),X射线光电子能谱仪(XPS)对复合材料进行了表征。结果表明高温退火使氮有效地掺入碳纳米管中,而碳纳米管仍保持原本征形貌。电化学测试表明:掺氮后复合电极首次放电比容量明显提高,达到882.5 mAh·g~(-1),90次循环过后具有89.46%的容量保持量,而PEG包覆使掺氮复合电极首次放电比容量提高至1109.7 mAh·g~(-1),经过90次循环放电比容量仍保持在995.2 mAh·g~(-1)。这说明掺氮和PEG包覆均能很好地改善复合材料的电化学性能。     

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。     

Electrochemical performances of hydrogen storage alloys treated using a new milling technique

A new self-made additive of amidocyanogen-acetic salt was used in wet bail-grind technique (WBGT) for preparing hydrogen storage alloys, and the effect on the electrochemical performance of the alloy electrode was investigated in detail. It was found that the prepared electrode had perfect electrochemical performances, such as rapid activation, high capability, high-rate discharge (HRD) ability, and good stability. The first discharge capacitance at 0.2 C (throughout this study, n C rate means that the rated capacity of a hydrogen storage alloy (full capacity) is charged or discharged completely in 1/n h) reached 278mAh.g-1 and the discharge capacitance reached the maximum of 322mAh·g-1 only after two charge-discharge cycles. For the dry method, wet method, and WBGT, the high rate discharge (HRD) values (C5C/C0.2C ratio) were approximately 0.59, 0.76, and 0.83, respectively. The stable discharge capacity at 3 C increased from 275mAh·g-1 (dry method) to 295mAh·g-1 (WBGT).     

PVdF-HFP-Based Gel Polymer Electrolyte with Semi-Interpenetrating Networks For Dendrite-Free Lithium Metal Battery

The safety issues and lower energy density of the lithium metal batteries are the two main challenges that hinder their applications in the fields of electric vehicles and portable devices.In this work,the semi-interpenetrated polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-based gel polymer electrolyte was synthesized through UV-curing method by employing the ethoxylated trimethylolpropane triacrylate (ETPTA) monomer.The semi-interpenetrating networks formed by polymerization of ETPTA and the high liquid absorption rate of the PVdF-HFP impart the as-prepared electrolyte with a high room temperature ionic conductivity of 3.17 × 10-3 s cm-1 and a high mechanical strength of 3.46 MPa.LiFePO4 was selected as cathode materials,and the active material loading of the cathode is about 4.2 mg cm-2.The electrolyte shows superior long-term cycling properties (127 mAh g-1 after 200 cycles at 0.5 C),excellent rate performance (113 mAh g-1 at 1 C,80 mAh g-1 at 2 C,and the discharge capacity of 135 mAh g-1 can be restored when the rate goes back to 0.1 C) as well as good ability to inhibit the growth of lithium dendrite (about 150 h).The facile synthesis strategy and great electrochemical performance of the electrolyte make it a potential candidate for lithium metal batteries.     

Synthesis and performance of Li3Ve(PO4)3/C composites as cathode materials

Carbon-coated Li3V2(PO4)3 cathode materials for lithium-ion batteries were prepared by a carbon-thermal reduction (CTR) method using sucrose as carbon source.The Li3V2(PO4)3/C composite cathode materials were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),and electrochemical measurement.The results show that the Li3V2(PO4)3 samples synthesized using sucrose as carbon source have the same monoclinic structure as the Li3V2(PO4)3 sample synthesized using acetylene black as carbon Source.SEM image exhibits that the particle size is about 1 μm together with homogenous distribution.Electrochemical test shows that the initial discharge capacity of Li3V2(PO4)3 powders is 122 mAh·g-1 at the rate of 0.2C,and the capacity retains 111 mAh·g-1 after 50 cycles.     

Zr-Ti系贮氢合金表面改性研究

采用化学镀镍、镀钴、机械混合以及球磨几种方法对Zr-Ti系贮氢合金进行了表面改性。XRD结果表明，随着镀镍量的增加，合金越趋向微晶化；球磨时间越长，合金的衍射峰更加弥散化，充放电试验结果表明，当镀镍量为15％(质量分数，下同)时，贮氢合金在60mA.g^-1的电流密度下初始容量比未处理的合金高出130mAh．g^-1，经过6次～8次循环完全活化，最大放电容量可达400mAh．g^-1，随着镀镍量的增加，抗自放电能力增加；当镀钴量为5％时，贮氢合金在60mA．g^-1的电流密度下初始容量比未处理的合金高出40mAh．g^-1，经过7次～9次循环完全活化，最大放电容量可达390mAh．g^-1，但随着镀钴量的增加，初始容量上升较快，但放电容量在减少；而机械混合仅提高初始容量，对最大放电容量没有改善；球磨不仅改善贮氢合金的活化性能，并且其最大放电容量可达450mAh．g^-1。     

前驱体体系pH值对LiFePO4/C正极材料性能的影响

采用溶胶-凝胶法制备了LiFePO4/C正极材料.采用X射线衍射(XRD)、扫描电镜(SEM)和电化学手段对材料进行了结构表征和性能测试.研究了其前驱体体系pH值对材料性能的影响.结果表明:当前驱体体系pH值为8.4时,LiFePO4/C正极材料具有最佳的电化学性能.在0.1C倍率下充放电,磷酸铁锂首次放电比容量为16...     

Synthesis and electrochemical properties of sol-gel derived LiMn2O4cathode for lithium-ion batteries

Spinel LiMn2O4 has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost, non-toxicity and easy manufacture. The spinel lithium manganese mixed oxides were prepared from lithium nitrate, manganese nitrate and citric acid by asol-gel method and were characterized by thermogravimetric analysis, X-ray diffraction, cyclic voltammetry and constant current charging-discharging technique. The different sintering temperatures for different time have strong influence on the structure, initial discharge capacity and cycling performance of the lithium manganese oxide. It shows that the lithium manganese oxides sintered at 700 ℃ for 10 h have a single spinel structure and better electrochemical properties. The initial discharging capacity can be up to 125.9 mAh·g-1 , even after six cycles, it still retains 109.1 mAh·g-1 .     

Synthesis and electrochemical properties of Th-doped LiMn2O4 powders for lithium-ion batteries

To improve the cycle performance of eco-friendly and cost-effective spinel LiMN2O4 as the Li secondary batteries, the Th-doped LiThxMn1-xO4 spinel powers were synthesized by solid-state method. The starting materials, Li2CO3,MnO2 and Th(NO3)4·4H2O, were mixed uniformly using a traditional ball milling, which resulted in a uniform particle size distribution in the mixed powers. Tests of X-ray diffraction, SEM, impedance spectra and charge-discharge were carried out for LiThxMn1-xO4 cathode materials. Results show that the synthesized LiTh0.01Mn1.99O4 material exhibits standard spinel structure, regular particle morphology and excellent property of charge-discharge for big current. The capacity retention of the material modified by doping Th is more than 85.1% of the first discharge specific capacity of 111.5 mAh·g -1 after 20 cycles at the current rate 1C, while the pristine LiMN2O4 is only 57% of the first discharge specific capacity of 110.2 mAh·g-1 after the same cycles at the same current rate.     

活性炭-CNT/PEG/硫复合材料的制备与储锂性能研究

通过密封加热熔融的方式制备了添加CNT的活性炭/硫锂离子电池正极活性材料,并对其进行PEG包覆复合改性,制备了C-CNT/S(PEG)正极复合材料。X射线衍射(XRD)图谱显示复合材料具有较强的非晶结构,且单质硫分散在碳材料的微孔之中。扫描电镜(SEM)显示CNT均匀分散在复合材料之中,并形成了三维导电结构。放电比容量测试显示CNT的加入提高了复合材料的放电比容量;PEG包覆的复合改性材料首次放电比容量高达1371.1 m Ah/g,循环50次后放电比容量为662.8 m Ah/g。说明添加CNT及PEG包覆复合改性,使活性炭/硫正极材料的电化学性能显著提高。