锂离子电池LiFePO4/聚并苯复合正极材料的合成与改性研究

通过固相法合成了LiFePO4 /聚并苯(PAS)复合材料.纯的LiFePO4电导率仅为(0.1～1)×10-9 S/cm,合成LiFePO4/PAs复合材料电导率为2.0 S/cm,复合材料的电导率提高了10个数量级.LiFePO4/PAS复合材料具有优异的电化学性能,在室温1C倍率下首次放电容量为140 mA·h/g,经过200次循环后容量仍保持最初容量的97.14%.说明通过包覆PAS材料极大地提高了LiFePO4的大电流充、放电容量和循环性能.     

纳米结构水系NiCo/Fe电池材料的制备及电化学性能的研究

可充电的水系电池由于价格低廉、电极材料来源丰富和使用安全等优势而得到研究者们广泛关注.但是其在实用中还存在着能量密度和功率密度不足的问题.该研究以针状NiCo2O4纳米棒为水系电池正极材料,以Fe3O4纳米棒为负极材料组装成了一种NiCo/Fe电池储能器件.该储能器件表现出了优异的可充放电性能,在1.2 kW/kg功率密度下(1 A/g),其最高容量可达207.7 Wh/kg(173 mAh/g),在24 kW/kg(20 A/g)的高速率充放电速率下,其容量仍能保持70.8 Wh/kg(59 mAh/g).此外,得益于正负电极材料均为阵列结构并与基底结合牢固,该储能器件表现出优良的循环性能,即在电流密度为5 A/g下经过2 000次循环后容量仍保持近80%.     

Effect of Na~+ in situ doping on LiFePO_4/C cathode material for lithium-ion batteries

Li_1-XNaXFePO₄(X = 0, 0.01 or 0.05) composite cathode materials were synthesized by the simple solvothermal method. SEM images showed that Na doping had little effect on the morphology of particles, which provided a guarantee for its excellent electrochemical performance. Charge/discharge data revealed that an appropriate amount of doped Na could improve electrochemical performance. Li_0.99Na_0.01FePO₄ showed excellent rate capacity and cycle s...     

Fabrication and electrochemical properties of 3D nano-network LiFePO_4@multiwalled carbon nanotube composite using risedronic acid as the phosphorus source

LiFePO_4@multiwalled carbon nanotubes(LFP@MWCNTs) nanocomposite has been fabricated using risedronic acid(RDA) as a new eco-friendly phosphorus source. Microscopic, spectroscopic, and electrochemical characterization demonstrate that the MWCNTs are in the form of coiled and cross-linking nanoribbon, which wrapped and encrusted around LiFePO_4 particles to form a three-dimensional(3D) nano-network composite.This microstructure of 3D nano-network is obtained due to the reactions between RDA's special functional groups with Fe~(2+) and C-OH,-C=O or-COOH on the surface of the functionalized MWCNTs. The results also show that the particle size of the fabricated LiFePO_4@MWCNTs composite is below 300 nm with the pure crystal of olivine. This nanocomposite indicates an enhanced reversible capacity of 162.2 mAh g~(-1) at 0.2C, and high capacity retention of 76.5% even at 10C after the 800 th cycles. The electric conductivity and Li~+ diffusion coefficient(D_(Li)~+) of the LiFePO_4@MWCNTs are 3.79 × 10~(-2)S cm~(-1) and 4.46 × 10~(-11) cm~2s~(-1), respectively.These improved electrochemical parameters can be attributed to the nano-sized effect of particles, MWCNTs' wrapping effect and 3D nano-network microstructure of the LFP@MWCNTs resulted from using RDA as a new phosphorus source.     

Synthesis/Structure and Cathode Properties of Li_2CoPO_4F for High-Voltage Li-ion Batteries

1 Results Although phospho-olivine LiFePO4 has attracted much attention as next-generation cathode, the gravimetric energy density is restricted. Fluorophosphate Li2CoPO4F is strong candidate for new high-voltage cathode with large capacity,if 2 Li can be reversibly removed[1]. In the present study, we tried to synthesized Li2CoPO4F by two methods, solid state reaction in vacuumed quartz tube with Pt crucible and melt-quench process using Cu single roller in Ar. The obtained latter amorphous sample was...     

Structure and electrochemical properties of LiLaxMn2-xO4 cathode material by the ultrasonic-assisted sol-gel method

Powders of spinel LiLa_xMn_2—xO₄ were successfully synthesized by the ultrasonic-assisted sol-gel (UASG) method. The structure and properties of LiLa_xMn_2—xO₄ were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscopy (SEM), galvanostatic charge-discharge test, and cyclic voltammetry (CV). XRD results show that the La³⁺ can partially replace Mn³⁺ in the spinel and the doped materials with La³⁺ have a larger lattice constant compared with pristine LiMn₂O₄. FT-IR indicates that the absorption peak of Mn³⁺−O and Mn⁴⁺− O bonds has a red and blue shift with the increase of doping lanthanum in LiLa_xMn_2—xO₄, respectively. The charge-discharge test exhibits that the initial discharge capacity of LiLa_xMn_2—xO₄ drops off, and the capacity retention increases gradually at C/5 discharge rate with the increase of doping lanthanum, and LiLa_0.01Mn_1.99O₄ has a higher discharge capacity and a better cycling performance at 1C discharge rate. CV reveals that the doping La³⁺ is beneficial to the reversible extraction and intercalation of Li⁺ ions.     

中空TiO2/S复合物的制备及作为高性能锂硫电池正极材料

以C球为模板,通过水热反应制备中空结构TiO_2;并通过液相渗入法与单质S复合,制备出锂硫电池正极材料TiO_2/S复合物。利用透射电子显微镜(TEM)、X-射线衍射(XRD)、热重分析(TG)测试手段对复合物进行形貌、结构及不同组分含量确定的表征;利用循环伏安法(CV)、电化学阻抗谱(EIS)、恒电流充放电测试方法对其进行电化学性能表征。结果证明,单质S与中空TiO_2成功复合;中空结构的TiO_2不仅提高了S正极的导电性,还能有效控制单质S的利用,以及缓解多硫化合物的"穿梭效应",进而大大提高电池的库伦效率和循环性能。     

双碳涂层LiMnPO4/C的制备及其电化学性能的研究

以碳酸锂、草酸锰和磷酸二氢铵为原料、抗坏血酸为还原剂和碳源、PEG400为分散剂,采用二次球磨混料二次煅烧并相结合的方法合成双碳涂层包覆纳米级磷酸锰锂,并用XRD、SEM和恒电流充放电技术研究了一次煅烧温度和时间、二次煅烧温度和时间对材料结构形态和电化学性能的影响。结果表明,在550℃煅烧3 h,650℃煅烧10 h的条件下所合成的LiMnPO4为橄榄石结构的纯相材料;材料晶粒的尺寸可达到几十纳米;在0.1 C下首次充电容量为110 mA·h/g,放电容量为87 mA·h/g,首次充放电效率为79%,经过50次循环后,放电容量保持率约为98%,具有一定的循环稳定性。     

LiFe1-x Mgx PO4/C的制备和性能研究

以乙酸镁为掺杂元素、蔗糖为碳源,采用固相反应法制备镁掺杂磷酸铁锂包覆碳复合材料LiFe1-xMgxPO4/C(x=0.01,0.02,0.03,0.04).利用X射线衍射(XRD)分析其结构,扫描电镜(SEM)观察其形貌,恒电流法测定其电化学性能.研究结果表明镁离子掺杂没有影响材料的结构,而是提高了其放电容量和循环性能.在这些样品中,LiFe0.98Mg0.02位PO4/C的容量最高,首次放电达到140.0 mAh/g;并且在80次循环后容量没有衰减反而增加到148.6 mAh/g左右.     

Synthesis, Characterization and Properties of LiFePO4/C Cathode Material

Lithium iron phosphate coated with carbon (LiFePO₄/C) was synthesized by improved solid-state reaction using comparatively lower temperature and fewer sintering time. The carbon came from citric acid, which acted as a new carbon source. It was characterized by thermogravimetry and differential thermal analysis (TG/DTA), X ray diffractometer (XRD), Element Analysis (EA) and Scanning electron microscope (SEM). We also studied the electrochemical properties of the material. The first discharge capacity of the LiFePO₄/C is 121 mAh·g⁻¹ at 10 mA·g⁻¹, at room temperature. When the current density increased to 100 mA·g⁻¹, the first discharge capacity decreased to 110 mAh·g⁻¹ and retained 95% of the initial capacity after 100 cycles. The LiFePO₄/C obtained shows a good electrochemical capacity and cycle ability at a large current density. Foundation item: Supported by the National Natural Science Foundation of China (20071026) Biography: ZHOU Xin-wen (1980-), male, Master, research direction: inorganic material chemistry.     

锂离子电池负极材料M_2P_2S_6(M=Ni,Mn)的合成及电化学性能研究

通过室温固相法合成M2P2S6(M=Mn,Ni)层状结构材料,经XRD,SEM,EDS,IR和TG进行表征.结果表明,Mn2P2S6由粒径为40~50 nm的纳米球堆积而成,Ni2P2S6由不同大小粒子组成块状结构.将M2P2S6(M=Mn,Ni)作为锂离子电池负极材料进行电化学测试表明,M2P2S6(M=Mn,Ni)的首圈放电比容量分别高达800 m Ah/g和911 m Ah/g,说明M2P2S6化合物可能是一个潜在的锂离子电池负极材料.1     

Morphological evolution and kinetic enhancement of Li2FexMn1-xSiO4/Ccathodes for Li-ion battery

Li_2MnSiO_4-based cathode materials possess reasonable work potentials and high theoretical capacities,while the practical energy/power densities are constrained by their inferior kinetics of Li~+ diffusion.In this work,the Pmn2_1-structure Li_2Fe_xMn_(1-x)SiO_4/C materials were synthesized via a solvothermal method and evaluated as Liion cathode materials,with notable morphological evolutions and tunable crystallographic habits observed after solvothermal process.The Li_2Fe_(0.33)Mn_(0.67)SiO_4/C material delivers an initial reversible capacity of 250.2mAh g~(-1)at 0.1 C(～1.51 Li~+insertion/extraction,1 C=166 mA g~(-1)),excellent high-rate capability(52.2 mAh g~(-1)at 5 C),and good long-term cyclability(64.6%after 196 cycles at 2 C).The enhanced electrochemical properties are attributed to the boosted ion/electron transports induced by preferred morphological and structural characteristics of Li_2Fe_(0.33)Mn_(0.67)SiO_4/C.     

Synthesis of spherical Li1.167Ni0.2Co0.1Mn0.533O2 as cathode material for lithium-ion battery via co-precipitation

xLi2MnO3·(1-x)LiNi0.4Co0.2Mn0.4O2(x=0.5) powders were synthesized from co-precipitated spherical metal carbonate,Ni0.2Co0.1Mn0.533(CO3)x.It has been found that the preparation of metal carbonate was si...     

高电压锂离子电池正极材料LiNi 0.5 Mn 1.5 O 4制备及改性

采用草酸铵共沉淀-高温固相烧结法合成了高电压尖晶石正极材料LiNi0.5Mn1.5O4及其掺杂改性材料LiNi0.4Mg0.1Mn1.5O4.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、恒流充放电测试等对所合成样品进行表征.XRD测试表明所合成的样品具有尖晶石结构,空间群为Fd3m.电化学测试表明,样品有两个主放电平台,分别为4.7V和4.1V.经过800℃煅烧的样品LiNi0.5Mn1.5O4具有最好的倍率性能.经过900℃煅烧的样品具有最好的循环性能,以0.1C充放电,最高放电比容量达到124.2mAh.g-1,循环30次后容量保持率达92.7%.Mg掺杂的改性样品LiNi0.4Mg0.1Mn1.5O4在0.1C倍率下循环30次后容量保持率达95.7%,Mg的掺杂可以提高该材料的循环性能.     

化学合成法制备锌镍电池负极材料锌酸钙

以摩尔比为1：2.02的Ca(OH)2和ZnO为原料,通过化学合成法制备锌酸钙.采用X射线衍射、热重分析、粒度分析、循环伏安以及模拟电池的充放电等方法,对制备的样品进行表征.研究结果表明:所制得锌酸钙样品的化学组成为Ca(OH)2·2Zn(OH)2·2H2O;样品的颗粒粒径分布均匀,平均粒径为23.18 μm;以该锌酸钙为负极活性物质的模拟锌镍电池具有很高的放电平台,达到1.686 V;制得的锌酸钙的实际比容量为195.8 mA·h/g,达到了理论比容量的56.4%.     

High temperature electrochemical discharge performance of LaFeO3 coated with C/Ni as anode material for NiMH batteries

Perovskite LaFeO₃ is considered as a promising new anode material for nickel/metal hydride batteries due to its low cost, environmental friendliness and high temperature resistance. However, the poor conductivity of LaFeO₃ material restricts the discharge ability, which is problematic for its future widespread application. To solve the above issue, in this study, we prepared C/Ni-coated LaFeO₃ composite in view of the excellent electrical conductivity of carbon and nickel metal. Results show that the C/Ni-coated LaFeO₃ composite delivers remarkably increased discharge capacity of ～345 mAh g^?1 at 60 ?°C in contrast to ～267 mAh g^?1 for pure LaFeO₃. Furthermore, the carbon and nickel not only increase the electrical conductivity of the LaFeO₃ but also reduces the agglomeration of the LaFeO₃, therefore, the C/Ni-coated LaFeO₃ composite serves superior long cycle-life, which maintains 60.9% after 100 cycles (52.9% for the LaFeO₃ sample). In overall, the electrochemical behavior of the C/Ni-coated LaFeO₃ composite confirms its high potential as nickel/metal hydride batteries for energy storage applications.     

Sn/C复合材料的制备及作为锂离子电池负极材料的性能

采用SnCl2.2H2O乙醇溶液浸渍竹炭和NaBH4还原方法制备出一种锂二次电池负极用Sn/C复合材料。考察了复合材料中Sn含量对产物收率、微观结构及电化学性能的影响。结果表明,Sn2+大部分进入到竹炭的孔道中,并被还原为单质Sn;当单质Sn与复合材料质量比为42.5∶100时,复合电极材料具有555.1mAh/g的可逆容量,循环20次后容量保持在423.8 mAh/g,显示出较好的实用性能。     

Synthesis of magnetically recoverable visible-light-induced photocatalysts by combination of Fe_3O_4/ZnO with BiOI and polyaniline

Magnetically recyclable photocatalysts with efficient performances under visible light were synthesized by combining Fe_3O_4/ZnO with BiOI and polyaniline(PANI). The FT-IR, XRD, HRTEM, SEM, EDX, XPS, UV–vis DRS,VSM, BET, and PL instruments were utilized for characterization of the as-prepared products. The activity tests exhibited that the superior rate constant in photocatalytic performance was achieved over the Fe_3O_4/ZnO/BiOI/PANI(20%) nanocomposite, which enhanced for more than 59.9, 10.0, and 6.57 times, as compared to those of the Fe_3O_4/ZnO, Fe_3O_4/ZnO/PANI, and Fe_3O_4/ZnO/BiOI photocatalysts in degradation of RhB, respectively.Successful photocatalytic degradations of MO/MB and photo reduction of Cr(VI) were also investigated to confirm the potential application of the photocatalyst in removal of various pollutants. The considerably enhanced activity pointed to a promoting effect of p-n-p heterojunctions formed between PANI, ZnO, and BiOI, and improved textural characteristics, which are benefit for improvement of the photocatalytic performances.     

Synthesis and characterization of spinel Li_(1.05)Cr_(0.1)Mn_(1.9)O_(4-z)F_z as cathode materials for lithium-ion batteries

Samples with the nominal stoichiometry Li_1.05Cr_0.1Mn_1.9O_4−z F _z (z=0, 0.05, 0.1, 0.15, and 0.2) were synthesized via the solid-state reaction method and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge/discharge, and slow rate cyclic voltammetry (SSCV) techniques. The results show that the pure spinel phase indexed to Fd3m can be obtained when z=0, 0.05, and 0.1. The substitution of F for O with z≤0.1 contributes to the increase of initial capacity compared with Li_1.05Cr_0.1Mn_1.9O₄ spinels. However, when the F-dopant content is designed to be 0.15 and 0.2, the Li_1.05Cr_0.1Mn_1.9O_4−z F _z samples deliver relatively low capacity and poor cycling properties at 55°C.     

基于微米氧化铁的LiFePO4/C正极材料制备及性能研究

文章以微米级氧化铁为原料,通过前驱体预处理合成LiFePO4/C正极材料,采用X射线衍射(XRD)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)等手段对合成的磷酸铁锂材料结构和微观形貌进行表征,考察了不同球磨时间对浆料粒径的影响,分析了前驱体预处理对合成产物性能提升的原因。结果表明,以微米氧化铁为原料,经过预处理后制备得到的LiFePO4/C正极材料的电化学性能具有明显改善,0.2C和1C条件下,放电容量较之前驱体未处理样品分别提高了22.5%和27.3%,合成样品性能改善的主要原因在于前驱体预处理降低了二次团聚体粒径。