Al,Zr dual-doped cobalt-free nickel-rich cathode materials for lithium-ion batteries

Nickel-rich and cobalt-free cathode materials have obvious advantages in the aspects of energy density and economic efficiency. However, these materials are restricted from being used in commercial lithium-ion batteries due to the problems of poor structural stability and rate capability. In this study, the aluminum and zirconium dual-doped Co-free Ni-rich LiNi_0.96Mn_0.04O₂cathode material(NMAZ) is prepared by a facile high-temperature solid-phase method. The obta...     

Methods for promoting electrochemical properties of LiNil/3Col/3Mnl/3O2 for lithium-ion batteries

One popular study of the recent research is to develop the cathode materials for lithium-ion batteries. As a new cathode material for lithium-ion batteries, the LiNil/3Col/3Mnl/3O2 has drawn widespread attention because of its high capacity, high cut-off voltage and high tap density. Its theoretical capacity is 277.8 mAh/g. The crystal structure of LiNil/3Col/3Mnl/3O2 is α-NaFeO 2 . The structural and morphological features of the LiNil/3Col/3Mnl/3O2 are introduced in this paper. The emphasis is to present the methods for promoting electrochemical properties. The electrochemical properties and structure characteristics are discussed. And the prospect of layered LiNil/3Col/3Mnl/3O2 is forecast in the end.     

基于Li2MnO3的富锂类高比容量锂离子电池正极材料的研究进展

综述了近几年来基于Li2MnO3的高比容量二元和三元富锂类锂离子电池正极材料的研究进展.重点讨论了富锂材料zLi2MnO3.(1-z)LiMO2(0相似文献   

Investigation on the electrochemical activation process of Li1.20Ni 0.32Co0.004Mn0.476O2

The lithium-rich layered oxides are one of the most attractive cathode materials for lithium-ion batteries.Here,two types of Li1.20Ni0.32Co0.004Mn0.476O2 were synthesized using Li2CO3 and LiOH as lithium sources.An electrochemical activation process occurs in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from Li2CO3(LLO-1),while no obvious activation in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from LiOH(LLO-2) is observed.Via advanced scanning transmission electron microscopy(STEM),we found that Li2MnO3-like structure is rich in the surface region of LLO-2.The study provides a direct explanation for the electrochemical activation of lithium-rich materials.The sample with more LiMO2-like phase at the surface region shows a better cycling performance.It is likely that more LiMO2-like phase at the surface region could stabilize the interface and improve the cycling performance of the Li-rich cathode materials.     

Nonstoichiometric Li1±x Ni0.5Mn1.5O4 with different structures and electrochemical properties

Li1±xNi0.5Mn1.5O4(x=0.05,0) spinel powders were synthesized using a solid-state reaction.Their structures were characterized by X-ray diffraction,scanning electron microscopy and Raman spectroscopy.Their electrochemical properties for use as active cathode materials in lithium-ion batteries were measured.The LiNi0.5Mn1.5O4,Li1.05Ni0.5Mn1.5O4 and Li0.95Ni0.5Mn1.5O4 samples crystallized in Fd 3m,Fd 3m and P4332,respectively.The LiNi0.5Mn1.5O4 and Li0.95Ni0.5Mn1.5O4 samples exhibited better cycle performance than the Li1.05Ni0.5Mn1.5O4 sample,while Li0.95Ni0.5Mn1.5O4 had the worst rate performance.Thus,it appears unnecessary to introduce nominal lithium nonstoichiometry in LiNi0.5Mn1.5O4 electrode materials.     

Electrochemical performance of a nickel-rich LiNi<Subscript>0.6</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.2</Subscript>O<Subscript>2</Subscript> cathode material for lithium-ion batteries under different cut-off voltages

A spherical-like Ni_0.6Co_0.2Mn_0.2(OH)₂ precursor was tuned homogeneously to synthesize LiNi_0.6Co_0.2Mn_0.2O₂ as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi_0.6Co_0.2Mn_0.2O₂ were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge-discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi_0.6Co_0.2Mn_0.2O₂ material obtained by calcination at 900℃ displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh·g-1 at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh·g-1 at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh·g-1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively.     

Synthesis and electrochemical properties of LiNi0.8Al0.2−xTixO2 cathode materials by an ultrasonic-assisted co-precipitation method

A new co-precipitation route was proposed to synthesize LiNi_0.8Al_0.2−xTi_xO₂ (x=0.0-0.20) cathode materials for lithium ion batteries, with Ni(NO₃)₂, Al(NO₃)₃, LiOH·H₂O, and TiO₂ as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi_0.8Al_0.2−xTi_xO₂ were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge-discharge tests, respectively. The results show that the optimal molar fraction of Ti, calcination temperature and time, and additional molar fraction of Li for LiNi_0.8Al_0.2−xTi_xO₂ cathode materials are 0.1, 700°C, 20 h, and 0.05, respectively. Ti doping facilitates the formation of the α-NaFeO₂ layered structure, and ultrasonic vibration improves the electrochemical performance of LiNi_0.8Al_0.2−xTi_xO₂.     

Ce-doped LiNi1/3Co（1/3-x/3）Mn1/3Cex/3O2 cathode materials for use in lithium ion batteries

LiNi1/3Co1/3Mn1/3O2 and Ce-doped LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized by a co-precipitation method and solid phase synthesis and characterized using X-ray diffraction(XRD) and scanning electron microscopy(SEM).The results indicated that the resultant cathode materials with different Ce content all had a good layer structure and high crystallinity.Electrochemical performance testing of the cathode materials showed that the discharge capacity increased with increasing Ce content while the initial reversible capacity attenuation decreased with Ce doping.When the Ce content of the cathode materials is x=0.2,and the current charge and discharge rate is a constant 0.2 C,the discharge capacity maintained 91% of its initial capacity after cycling 50 times.     

尖晶石型Li-Mn-O多元素掺杂的高温电化学特性

采用高温固相浸渍法合成了多元复合掺杂尖晶石型锰酸锂Li 1.02MxMn 2-xQyO 4-y正极材料.XRD表征合成的产物均为良好的尖晶石型结构材料;SEM表明所合成的产物颗粒均匀且有良好的粒径分布.以该物质作为锂离子电池的正极材料组装成扣式电池,经充放电循环测试可知:多元素掺杂的尖晶石型锰酸锂正极材料Li 1.02CoaCrbLacMn 2-a-b-cFyO 4-y较富锂尖晶石和单元素Co、Cr掺杂的正极材料能够更好地抑制电池的可逆容量在充放电过程中的衰减,循环性能有了很大改善,表现出很好的电化学可逆特性,80次循环后放电容量仍能保持94.5%以上;特别是高温(55 ℃)性能更加突出,40次循环后放电容量仍能保持102.1mA.h/g(91.5%)以上.作为锂离子电池的正极材料,该复合掺杂材料是众多取代钴酸锂材料中最具竞争力的材料之一,也有望成为锂离子动力电池的正极材料.     

Comparative study of different membranes as separators for rechargeable lithium-ion batteries

Membranes of polypropylene (PP), PP coated with nano-Al₂O₃, PP electrospun with polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), and trilayer laminates of polypropylene-polyethylene-polypropylene (PP/PE/PP) were comparatively studied. Their physical properties were characterized by means of thermal shrinkage test, liquid electrolyte uptake, and field emission scanning electron microscopy (FESEM). Results show that, for the different membranes as PP, PP coated with nano-Al₂O₃, PP electrospun with PVdF-HFP, and PP/PE/PP, the thermal shrinkages are 14%, 6%, 12.6%, and 13.3%, while the liquid electrolyte uptakes are 110%, 150%, 217%, and 129%, respectively. In addition, the effects on the performance of lithium-ion batteries (LiFePO₄ and LiNi_1/3Co_1/3Mn_1/3O₂ as the cathode material) were investigated by AC impedance and galvanostatic charge/discharge test. It is found that PP coated with Al₂O₃ and PP electrospun with PVdF-HFP can effectively increase the wettability between the cathode material and liquid electrolyte, and therefore reduce the charge transfer resistance, which improves the capacity retention and battery performance.     

Electroch emical properties and interfacial reactions of LiNi0.5Mn1.5O4-δ nanorods

LiNi0.5Mn1.5O4-δ which possesses a high voltage of 4.7 V vs.Li+/Li and stable structure has been considered as a promising cathode material for high energy Li-ion batteries.In this study,well-crystalli...     

MXene and MXene-based materials for lithium-sulfur batteries

Lithium-sulfur (Li–S) batteries are regarded as potential alternatives to lithium-ion batteries due to their extremely high theoretical energy density. Nevertheless, Li–S batteries still suffer from low coulombic efficiency, low sulfur utilization, and poor cycling life, which hinder their further applications. To obtain ideal Li–S cells, intensive work has been dedicated to improve the conductivity of the electrode, inhibiting the shuttle of lithium polysulfides, and promoting the redox of sulfur. Two-dimensional transition metal carbides, nitrides or carbonitrides, also known as MXenes, attracting significant research interest in Li–S batteries due to their high conductivity, abundant active sites, layered structure and adjustable surface chemistry. In this review, we summarize the partial etching methods of MXenes with different surface terminations, the role of MXenes in Li–S batteries and MXene-based composites designed for Li–S batteries based on interfacial chemistry and interlayer structure. In the end, we also propose the perspectives of MXenes for Li–S batteries.     

电动汽车动力电池正极材料研究进展

电动汽车已成为未来汽车的主要发展方向之一,动力电池是电动汽车的核心部件,动力电池技术则是电动汽车发展的核心技术.总结了传统锂离子电池正极材料的优缺点,及对它们的改性研究,着重介绍了LiFe-SiO4、LiVPO4F、Li3V2(PO4)3和纳米正极材料的研究现状和性能改进方法,并对其发展方向进行了展望.     

以竹纤维为模板制备微米管状Li4Ti5O12负极材料

以竹纤维为模板,Ti(OC4H9)4和Li(Ac).2H2O为原料,用模板法制备锂离子电池微米管状Li4Ti5O12负极材料。采用XRD,SEM,BET,充放电实验和交流阻抗等对合成材料的结构、形貌和电化学性能进行表征。研究结果表明:制备的微米管状Li4Ti5O12负极材料由尖晶石型纳米Li4Ti5O12颗粒构成,具有较大的比表面积,该材料具有良好的电化学性能,在0.5~3.0 V,0.1C倍率下的首次放电比容量为178 mA.h/g,充放电循环100次后放电比容量仍保留162 mA.h/g,且倍率性能优异。     

Synthesis and modification of well-ordered layered cathode oxide LiNi<Subscript>2/3</Subscript>Mn<Subscript>1/3</Subscript>O<Subscript>2</Subscript>

Oxalic-acid-based co-precipitation method was employed to prepare LiNi_2/3Mn_1/3O₂ sample with a high-ordered structure. Li⁺, Ni²⁺ and Mn²⁺ acetates were used as starting materials. The influence of the amount of lithium source in the starting materials on Li⁺ content, disorder of Li⁺-Ni²⁺ ions, and electrochemical performance has been investigated. Rietveld refinement shows that the sample prepared with 20% excess Li-source in the starting materials exhibits a perfect ordered structure. A specific discharge capacity is as high as 172 mAh/g at C/20 in the voltage range of 4.35–2.7 V. However, the cyclability is not satisfactory: about 25.3% fade in capacity was observed over 50 cycles. Chemically stable SiO2 was coated on the surface of LiNi_2/3Mn_1/3O₂ particles. A significant improvement in cyclability was attained with 3 wt% SiO2 coating, which is ascribable to the protection of LiNi_2/3Mn_1/3O₂ particles from being dissolved into the electrolyte.     

Composite cathode and anode films for rechargeable lithium batteries

Recently the rechargeable Li and Li-ion polymer batteries have improved due to development of Li-ion conductive gel electrolytes and of high energe granting intercalation compounds. In our laboratory the composite cathodic film, the composite carbon anode film and PVC-based electralyte film were successfully prepared by casting procedures. Cycling experiments of the cells with Li or composite carbon anode in contact with PVC-based electrolyte and composite cathode were performed. Relatively good performance of the cell with Li anode, the composite cathode and LiPF₆-EC-DEC electrolyte was achieved in that over 50 cycles were possible with minimal capacity loss upon cycling. The same cell with PVC-based electrolyte was cycled over 20 cycles. Replacing Li anode by composite carbon anode, the cell behaved like the latter. It is found that appropriate amount of carbon content is helpful to improving specific capacity.     

Nanostructured LiMn2O4 and their composites as high-performance cathodes for lithium-ion batteries

Improvement of the energy density and power density of the lithium-ion batteries is urgently required with the rapid development of electric vehicles and portable electronic devices. The spinel LiMn2O4 is one of the most promising cathode materials due to its low cost, nontoxicity, and improved safety compared with commercial LiCoO2. Developing nanostructured electrode materials represents one of the most attractive strategies to dramatically enhance battery performance, such as capacity, rate capability and cycling life. Currently, extensive efforts have been devoted to developing nanostructured LiMn2O4 and LiMn2O4/carbon nanocomposites to further improve the rate capability of lithium-ion batteries for high-power applications. In this paper, recent progress in developing nanostructured LiMn2O4 and LiMn2O4/carbon nanocomposites is reviewed, and the benefits to the electrochemical performance of LiMn2O4-based cathodes by using these electrode materials are also discussed.     

醋酸盐体系无焰燃烧合成LiMn_2O_4及性能研究

以醋酸锂和醋酸锰为原料,浓硝酸为辅助氧化剂,在温度600℃、时间3 h下采用无焰燃烧合成尖晶石型Li Mn2O4锂离子电池正极材料,研究了不同浓度硝酸对制备尖晶石型Li Mn2O4的影响.通过XRD和SEM分别研究了产物的物相组成及微观形貌;通过电性能测试研究了产物的比容量变化.实验结果表明,当n(Li)∶n(Mn)=1∶2(mol/mol)时,可得到Li Mn2O4单相,硝酸浓度对燃烧产物颗粒影响也较大;硝酸浓度为15 mol/L时产物初始放电比容量为112.1 m Ah/g,40次充放电循环后,放电比容量为99.0 m Ah/g,容量保持率为88.3%,具有较好的容量及存储性能.     

尖晶石锰酸锂动力电池性能及应用

100Ah动力电池采用尖晶石锰酸锂作为正极材料,400Ah电池组应用于纯电动车,实验表明电池具有良好的电化学性能和安全性能。     

Preparation and performance of LiNi0. 8Co0.2O2 cathode material based on Co-substituted α-Ni（OH）2 precursor

Co-substituted α-Ni（OH）2 was synthesized by a novel microwave homogeneous precipitation method in the presence of urea. LiNi0.8Co0.2O2 cathode material was synthesized by calcining Co-substituted α-Ni（OH）2 precursor and LiOH·H2O at 900℃for 10 h in flowing oxygen. XRD, FTIR, FESEM and electrochemical tests were used to study the physical and the electrochemical performances of the materials. The results show that the prepared LiNi0.8Co0.2O2 compound has a good layered hexagonal structure. Moreover, the LiNi0.8Co0.2O2cathode material demonstrates stable cyclability with a high initial specific discharge capacity of 183.9 mAh/g. The good electrochemical performance could be attributed to the uniform distribution of Ni^2＋ and Co^2＋ ions in the crystal structure and a minimal cation mixing in LiNi0.8Co0.2O2 host structure.