Synthesis and electrochemical performances of LiCoO<Subscript>2</Subscript> 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 temperature calcining. Subsequently, Li₂CO₃, LiOH·H₂O and LiAc·2H₂O were added into the recycled powders to adjust the Li/Co molar ratio to 1.00. The new LiCoO₂ was obtained by calcining the mixture at 850°C 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 performance. The first discharge capacity is 160 mAh·g⁻¹ between 3.0–4.3 V. The discharge capacity after cycling for 50 times is still 145.2 mAh·g⁻¹.     

Microwave synthesis of LiCoO2 cathode materials

1INTRODUCTION LiCoO2isacommerciallyusedcathodemateri alforlithiumionbattery.Comparedwithothercathodematerials,suchasLiNiO2,LiMn2O4and theirdopedcompounds,LiCoO2hastheadvanta gesofhighpotential,excellentreversibility,longcyclelifeandreliableperformance[14].Thereare mainlyseveralmethodsforsynthesisofLiCoO2,suchasconventionalceramicmethod[5,6],sol gel synthesis[7],andlow temperaturesolutioncom bustion[8].Amongthesemethods,theconvention alceramicmethodhasbeenappliedtoindustrial productio…     

Surface modification and characterization of F-Co doped spinel LiMn2O4

Spinel LiCo0.09Mn1.91O3.92F0.08 as cathode material was modified with LiCoO2 by the sol-gel method, and the crystal structure, morphology and electrochemical performance were characterized with XRD, SEM, EDS, AAS and charge-discharge test in this paper. The results show that a good clad coated on parent material can be synthesized by the sol-gel method, and the materialswith modification have perfect spinel structure. LiCo0.09Mn1.91O3.92F0.08 materials coated by LiCoO2 improve the stability of crystal structure and decrease the dissolution of Mn into electrolyte. With the LiCoO2 content increasing, the specific capacity and cycle performance of samples are improved. The capacity loss is also suppressed distinctly even at 55 ℃.     

Effect of annealing temperature on structure and electrochemical properties of LiCoO2 cathode thin films

LiCoO2 thin films, which can be used as a cathode material in microbatteries, were deposited using radio frequency (r.f.) magnetron sputtering system from a LiCoO2 target and in an O2+Ar atmosphere.The films were characterized by various methods such as XRD, SEM and AFM.The LiCoO2 films were annealed in air at 300, 500, 700 and 800 ℃ respectively.The effect of the annealing temperature on the structure, the surface morphology and the electrochemical properties of the films were investigated.The LiCoO2 thin film deposited at room temperature is amorphous and has smaller grain size.With increasing of annealing temperature, the crystallinity of the films is promoted.When the annealing temperature increases to 700 ℃, the films have a perfect crystalline LiCoO2 phase.The LiCoO2 thin film without annealing has no discharge plateau and small discharge capacity (about 27 μAh·cm-2μm).The discharge capacity increases with the increasing of annealing temperature and reaches 47 μAh·cm-2μm for the film annealed with 700 ℃, which also shows the typical discharge plateau of 3.9 V.The cycle performance of LiCoO2 thin films of as grown and annealed at different temperatures were studied.In the case of the film without thermal treatment, the capacity fading is much faster than that of the film annealed at different temperature, showing about 40% capacity loss only after 25 cycles.However, in the case of the film annealed at 700 ℃, the capacity reaches to steady state gradually and maintained constantly with cycling.After 25 times cycling, the discharge capacity of the film annealed at 700 ℃ decreases to about 36.9 μAh·cm-2·μm, only 0.8% capacity loss per cycle.     

尖晶石LiMn2O4和LiCoO2与电解液的相容性

研究锂离子电池正极活性材料尖晶石LiMn2O4和LiCoO2与6种电解液充、放电时的相容性。用X射线衍射检测自制的LiCoO2试样和尖晶石LiMn2O4试样的结构；用粉末微电极循环伏安法测定6种电解液在导电剂乙炔黑表面的氧化电位；将制得的尖晶石LiMn2O4试样和LiCoO2试样在上述电解液中进行恒电流充放电实验。结果表明：充电至高电位3．3～4．3V（vs Li／Li^＋）时，如果正极活性材料表面与电解液发生不可逆反应并在其上覆盖一薄层电子不可导的钝化膜，则将导致活性材料的充、放电效率降低，放电容量减少，即正极活性材料与电解液的相容性差；反之，则相容性好；尖晶石LiMn2O4与上述6种电解液的相容性都很好，普适性强；LiCoO2与上述6种电解液的相容性差别较大，呈选择性。     

Mg-Y共掺杂高电压钴酸锂正极材料的合成及其性能研究

将Co3O4、Li2CO3、Mg(OH)2 和Y2O3 按一定化学计量比称取并混合均匀后,采用高温固相法合成LiCo1-x-yMgxYyO2正极材料并探究了Mg-Y 共掺杂对钴酸锂高电压性能的影响.采用X 射线衍射(XRD)和扫描电镜(SEM)分别表征其晶体结构和形貌.LiCo1-x-yMgxYyO2正极材料高电压性能...     

废旧LiCoO2材料再生LiNi0.8Co0.1Mn0.1O2正极材料及性能研究

针对废旧锂离子电池数量不断增加的现状,对废旧LiCoO2电池的回收和再生流程进行探究。以废旧LiCoO2电池为原料,通过预处理,酸浸,共沉淀步骤,实现了LiNi0.8Co0.1Mn.1O2正极材料的再生。ICP-OES分析浸出液中的元素含量,SEM和XRD表征材料形貌和结构,扣式电池的电化学测试定量分析材料的电化学性能。研究表明,利用浸出液可以再生形貌和层状结构良好的正极材料,在0.2C,2.8~4.3V电压范围内进行充放电循环测试,首周放电比容量可达到210.8 mAh/g,经过50周充放电循环后的容量保持率为87%,表现出良好的循环稳定性,为废旧锂离子电池的再生提供支撑和发展方向。     

LiCoO2结构及性能与锂离子电池电压特性的关系

采用激光衍射 ,BET ,XRD ,SEM等方法 ,研究了系列LiCoO2 正极材料的一些物理化学性能及其与锂离子电池电压特性的关系 ,并对由 3种LiCoO2 样品制成的试验电池进行了电压特性和循环寿命的测试 ,得出了制备有良好电压特性的锂离子电池用LiCoO2 正极材料所应具备的性能 :XRD谱线中I0 0 3 /I10 4 的值较大 ,颗粒分布均匀无团聚 ,表面光滑平整。     

高振实密度球形LiNi_(0.5)Co_(0.3)Mn_(0.2)O_2粉末的合成及性能

以共沉淀法制备的球形Ni_(0.5)Co_(0.3)Mn_(0.2)CO_3粉末为前驱体,按一定的比例将碳酸锂与前驱体混合,然后采用高温固相法合成高振实密度球形LiNi_(0.5)Co_(0.3)Mn_(0.2)O_2正极材料.该材料的振实密度达到2.60 g/cm~3,与商品化LiCoO_2的密度相当.SEM分析表明, LiNi_(0.5)Co_(0.3)Mn_(0.2)O_2正极材料与前驱体形貌有良好的继承性,均为理想的球形.XRD物相分析表明,在不同合成温度下的Li Ni_(0.5)Co_(0.3) Mn_(0.2)O_2产物均为具有α-NaFeO_2层状结构的纯相物质,在较高合成温度下所得材料的结晶度较高.电化学性能研究表明,在2.7～4.3 V的电压范围内,电池的放电比容量在0.2C倍率下为168.1 mA-h/g,在1C倍率下为157.6 mA-h/g;经50次循环后,两种放电条件下的电池容量保持率分别为95.1%和97.2%,显示出良好的电化学性能.     

LiC0O2电极材料晶体结构的XRD和TEM研究

报道了X射线衍射和电子衍射在研究锂离子正极材料LiC0O2晶体结构中的作用。测定了不同温度下合成的LiC0O2以及脱锂态产物LixC0O2（0〈x〈1）的晶体结构。X射线衍射反映了LiC0O2粉末颗粒晶体结构的统计性集体特征，电子衍射反映了LiC0O2单颗粒的精细晶体结构特征，2种方法结合起来才能较为全面地考察LiC0O2粉末颗粒的晶体结构，从而为采取综合措施提高其电化学性能提供依据。     

Self-lubricating ceramic cutting tool material with the addition of nickel coated CaF2 solid lubricant powders

A new type of self-lubricating ceramic cutting tool material with the addition of metal coated solid lubricant powders was developed. Nickel coated CaF₂ composite powders with core–shell structure were produced by electroless plating technique. The growth process of nickel coating on the solid lubricant CaF₂ powders was analyzed. The as-prepared self-lubricating ceramic cutting tool material made by adding nickel coated CaF₂ powders exhibited notable improvements in microstructure and mechanical properties, in comparison with the corresponding cutting tool material made by directly adding uncoated CaF₂ powders. Cutting tests show that the new type of self-lubricating ceramic cutting tool has better antifriction property and wear resistance than the corresponding cutting tool.     

Preparation and electrochemical properties of nanosized tin dioxide electrode material by sol-gel process

1　INTRODUCTIONTinoxideisawideenergy gapsemiconductorandhasfoundmanytechnologicalapplicationssuchascatalystsforoxidationoforganics,solid stategassen sorsandopticalelectronicdevices[1,2 ] .Recently ,sev eraltin oxide basedcompoundswerereportedtobegoodcandidatesasanodesforlithiumionbatteriesin steadofcarbonaceouselectrodes[36 ] ,theelectro chemicalreactionoccurringinthesecompoundsisnottheintercalationoflithiumintoahoststructure .Forbulksamplesofamorphousandcrystallinetinoxide ,adecomposition…     

钽铌电子材料新进展

通过降低杂质含量、改善物理性能等新技术以及Ta2O5钠还原制取高比电容钽粉、TaCl5低温钠还原制取纳米级钽粉的新工艺方法,生产了性能优良的高比容钽粉,并研究了其微观结构;同时开发了制造高比电容铌粉、一氧化铌粉的新技术,制得了高性能的电容器级铌粉和一氧化铌粉,为铌电容器作为一种新类型电容器产业参与竞争提供了优质的基础材料.     

纳米晶La0.7Pb0.3FeO3的制备及其对CO敏感特性的研究

利用溶胶-凝胶法制备了纳米晶La0.7Pb0.3FeO3气敏材料,并对其相组成、电导及其对CO气敏性能进行了研究.XRD结果表明：掺铅固溶体La0.7Pb0.3FeO3仍为正交晶系钙钛矿结构,粒径约为17nm,低于纯相LaFeO3的粒径31nm。电导测鼍显示：该材料足P型半导体导电行为，电导大于同温度下纯相LaFeO3的电导，且电导突变温度有所降低。气敏性能研究表明：Pb掺杂对其CO气敏性能有了明显改善。     

纳米晶La_(0.7)Pb_(0.3)FeO_3的制备 及其对CO敏感特性的研究

利用溶胶-凝胶法制备了纳米晶La0.7Pb0.3FeO3气敏材料,并对其相组成、电导及其对CO气敏性能进行了研究。XRD结果表明:掺铅固溶体La0.7Pb0.3FeO3仍为正交晶系钙钛矿结构,粒径约为17nm,低于纯相LaFeO3的粒径31nm。电导测量显示:该材料呈p型半导体导电行为,电导大于同温度下纯相LaFeO3的电导,且电导突变温度有所降低。气敏性能研究表明:Pb掺杂对其CO气敏性能有了明显改善。     

二氧化钛纳米粉体的可控水热合成研究

采用TiCl_4为原料,用水热法合成了二氧化钛纳米粉体,讨论了水热反应条件对二氧化钛粉体结构和微观形貌的影响.结果表明:在0.5～1.0 mol/L TiCl_4, 130～190 ℃, 3～9 h的水热条件下,合成的TiO_2纳米粉体属于金红石相;TiO_2的形貌和尺寸与原料浓度、反应时间和反应温度密切相关,随着原料浓度的增加、反应温度的升高以及反应时间的延长,TiO_2形貌由球形纳米粒子向纳米棒转变,其尺寸也随之增大.     

钛铁矿直接制备Ti(C,N)复合粉的组织与特性

以钛铁矿(FeTiO3)为原料,用碳热还原技术制备含Fe-Ti(C,N)复合粉。用酸浸工艺对复合粉进行分离提纯,并对其物相进行定性分析,对其化学组成进行定量分析,对其物理特性(如形貌、粒度、比表面积)进行测试。结果表明,Fe-Ti(C,N)复合粉主要由Ti(C,N)、α-Fe组成,其中Ti(C,N)占50.25%,α-Fe占44.08%,粉体呈不规则形状,粒度约为2~3μm,比表面积为2.39 m2.g-1。酸浸分离的Ti(C,N)粉体纯度为97%,其性能指标已达到商品粉的要求。     

研制厚膜敏感陶瓷材料的新方法

重点研究以Ba1-xSrxTiO3和(V1-xCrx)2O3为主要基体的双基体PTC热敏厚膜材料的相关特性。用(V1-xCrx)2O3取代价格昂贵的RuO2和银粉，不仅降低了室温电阻率，消除了非欧姆接触，同时提高了厚膜材料的性能，并显著降低了成本。独立地设计了用化学共沉淀方法制备Ba1-xSrxTiO3微粉的2个化学反应方程式，深入分析了聚乙二醇和无水乙醇在制备纳米粉时所起的防止颗粒发生团聚现象的作用。     

Synthesis of titanium carbide by thermo-chemical methods with TiH2 and carbon black powders

A new synthesizing method for producing submicron TiC powders was studied by using TiH₂ and carbon black powders. It is well known that hydrogen absorption transforms titanium from metal (h.c.p.) to brittle hydride (f.c.c.) powders by ball-milling. This research focused on obtaining submicron-sized TiC powders from the ball-milled mixture of TiH₂ and carbon black by thermal treatment. The hydrogen, carbon, iron, and oxygen composition changes in the mixed powders were analyzed. Thereafter, a differential thermal analysis (DTA) test was performed to observe change of phase with ball-milling time. The TiC powders were obtained by heat treating the powders milled for 5h at various temperatures (600–1200°C). The phase microstructure was investigated via DTA, X-ray diffraction (XRD), and scanning electron microscope (SEM). The mixture milled for 2h had an f.c.t. structure containing 66.73 at. %H transformed to f.c.c. by milling for 4h. After 5h of ball-milling, submicron-sized particles of 273 nm were obtained. At the isothermal heat-treating temperature of 500°C, the Ti single phase was formed completely, and the TiC phase of lattice parameter 0.310 nm was completely formed over the temperature of 1000°C.     

锂电池中铝箔表面形貌对电池性能的影响

10～20μm厚的铝箔经常应用于锂电池的阴极。将被化学腐蚀的粗糙表面铝箔与光滑平面的铝箔进行对比,以考察铝箔的表面形貌对锂电池的影响。对于高电导率且颗粒较大的LiCoO2锂电池材料,两种铝箔的锂电池性能没有明显不同。但是对于低电导率且颗粒较小的LiFePO4材料,高倍率放电性有很大的差异。通过优化铝箔的表面形貌及电池材料的颗粒尺寸,可使电池的性能得到提高。