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...     

纳米Ni(OH)2的制备及其电化学性能

采用固相法制备了纳米β-Ni(OH)2, 采用Scherrer公式由其中一样品的(100)、 (101)及(110)晶面参数计算得到晶粒尺寸分别为11.1 nm、 3.6 nm和12.1 nm. 采用循环伏安、恒电流充放电等技术对其电化学性能进行了初步研究, 结果表明 纳米Ni(OH)2的活性比较高, 其首次容量达207.9 mA*h*g-1, 第2周期容量即达到最大值240.4 mA*h*g-1, 但其容量衰退较快.     

尖晶石锰酸锂制备及其电化学性能的研究

锰酸锂被认为是取代商品锂离子电池正极材料LiCoO2的候选材料,以二氧化锰、碳酸锂为原料,在空气气氛下进行烧结,控制烧结温度和时间,制备锂离子电池正极材料锰酸锂。用X射线衍射仪、电子扫描电镜对产物的结构特征、微观表面形貌和恒流充放电性能进行了表征。结果表明:所制得的正极材料为尖晶石型锰酸锂,结晶度高、无杂质相、材料颗粒的粒径均匀,首次充放电比容量为117.3 mAh/g(0.2C,3.3～4.4V);50次循环后,放电比容量为107.9 mAh/g,不可逆容量损失为9.4 mAh/g,比容量保持率为92.0%,得到了很好的综合电化学性能。     

Mg2+掺杂对LiFePO4结构及电化学性能的影响

以MgAC2为掺杂源,采用固相反应法在惰性气氛下合成了掺Mg的LiFePO4正极材料,考察了Mg2 对于目标化合物物理及电化学性能的影响.采用粉末X射线衍射和扫描电镜技术对产物的结构、形貌及粒度等进行了表征,通过恒电流充放电和交流阻抗技术对其电化学性能进行了研究.结果表明:少量的Mg2 掺杂并未影响产物结构,但却有利于减小LiFePO4电荷转移过程中的阻抗,克服该过程中的动力学限制.在0.1C倍率下放电,掺杂LiFePO4与未掺杂LiFePO4的初始放电容量分别为136.9和111.8 mA·h/g,循环50次后,容量分别为135.6和83.9 mA·h/g;与未掺杂的LiFePO4相比,掺镁后的LiFePO4具有更为优良的循环性能.     

废锂离子电池中失效钴酸锂材料超声再生

为了恢复锂离子电池中正极钴酸锂材料的电化学活性,对置于LiOH溶液中的失效钴酸锂进行超声再生研究。采用XRD和Raman光谱分析钴酸锂晶体结构,采用SEM分析钴酸锂表面形貌和颗粒大小,采用FT-IR光谱仪和TGA热分析仪分析钴酸锂表面粘附的有机物。结果表明:超声空化效应可以有效地去除钴酸锂表面的有机物,并有利于钴酸锂晶体在LiOH溶液中Co和Li阳离子的重排。室温条件下,失效的钴酸锂在2.0 mol/L LiOH溶液中经过12 h超声处理后,成功恢复了其电化学活性。锂离子电池的首次充电容量为132.2 mA·h/g,首次放电容量为131.9 mA·h/g,第50次循环时的电容保持率为97.2%。     

锂离子电池纳米ε-VOPO_4正极材料的合成与电化学性能

以V_2O_5、H_3PO_4为原料,在V_2O_5与H_3PO_4摩尔比为1:2.4条件下通过水热法制各VOPO_4·xH_2O,得到的VOPO_4·xH_2O再通过650℃煅烧制备纳米结构ε-VOPO_4,通过X射线衍射对制备材料进行表征。采用SEM对产物形貌进行观察,考察原料配比条件对产物组成和晶相的影响;对纳米ε-VOPO_4进行电化学性能测试。结果表明:在该条件下制备出的纳米ε-VOPO4物相纯;所制备纳米结构的ε-VOPO_4颗粒粒径为200 nm,且颗粒度均匀;在0.2C倍率、电压范围为2.0~4.3 V充放电制度下,首次充电比容量可以达到227.9 mA·h/g,在0.5C倍率充放电制度下循环140次后,放电容量达160.49 mA·h/g。     

LiMn2O4正极材料的合成及电化学性能

根据Li2CO3／MnO2混合粉体的TG-DSC分析结果，采用高温固相反应法，在不同的预保温温度下合成出正极材料LiMn2O4。对其进行XRD，SEM表征和电化学性能测试，确定了在600℃预保温和830℃最终合成的优化工艺。该工艺合成的LiMn2O4粉体具有单一的尖晶石相结构和粒度分布均匀的形貌。组装成电池在常温下循环时，初始放电比容量达122mAh／g，20次循环后容量保持在96％左右。其循环伏安曲线经过20次循环后仍可保持较好的形状。     

尖晶石型LiNixMn2-xO4锂离子正极材料的电化学性能

采用Pechini法在800℃空气中焙烧6h制备LiNixMn2-xO4试样(x＝0，0．05，0．1，0.2，0．3，0．4，0．5)。经XRD测试表明除LiNi0.5Mnl．5O4以外，其它的试样均为纯净的尖晶石结构。尖晶石LiNixMn2-xO4试样电极在3．3—4．5V以及4．5—4．8V范围内的电化学性能测试表明：在3．3—4．5V范围内，试样初始充放电容量随Ni元素掺杂比例的增加而降低；在4．5—4．8V范围内，试样初始充放电容量随Ni元素掺杂比例的增加而增大；在3．3—4．8V范围内，试样总的初始容量基本不变；在3．3—4．5V范围内，试样的循环性能随Ni元素掺杂比例的增加而提高。     

固相法制备Y3+掺杂LiFePO4/C的反应机理及其电化学性能

以Fe2O3为铁源,采用高温固相法制备了Y3+掺杂的LiFePO4/C复合材料。利用TG-DSC、XRD、SEM、恒电流充放电等手段对材料的合成反应历程、粉体颗粒形貌以及电化学性能进行了研究。结果表明:Fe3+在300～550℃间被还原为Fe2+,经过650℃煅烧后,形成晶型单一的橄榄石结构晶体。LiFe0.98Y0.02PO4/C样品在0.2 C倍率下的首次放电比容量达到了151.6 mA.h/g。     

锂离子电池正极材料LiMnO_2的表面修饰及电化学性能

运用热处理技术分别制备B2O3、CuO和FePO4包覆的LiMnO2锂离子电池正极材料。采用X射线衍射(XRD)和扫描电镜(SEM)对材料的晶体结构和表观形貌进行分析,通过恒电流充放电以及电化学阻抗技术(EIS)分析其电化学性能。结果表明:包覆后材料的电化学阻抗与Warburge阻抗值有所增大,但包覆能有效抑制正极材料LiMnO2在电化学过程中锰的溶解,改善和提高材料的充放电循环性能和结构的稳定性。     

Effects of synthesis conditions on the structural and electrochemical properties of layered LiNi1/3Co1/3Mn1/3O2 cathode material via oxalate co-precipitation method

The uniform layered LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion batteries was prepared by using (Ni1/3Co1/3Mn1/3)C2O4 as precursor synthesized via oxalate co-precipitation method in air. The effects of calcination temperature and time on the structure and electrochemical properties of the LiNi1/3Co1/3Mn1/3O2 were systemically studied. XRD results revealed that the optimal calcination conditions to prepare the layered LiNi1/3Co1/3Mn1/3O2 were 950°C for 15 h. Electrochemical measurement showed that the sample prepared under the such conditions has the highest initial discharge capacity of 160.8 mAh/g and the smallest irreversible capacity loss of 13.5% as well as stable cycling performance at a constant current density of 30 mA/g between 2.5 and 4.3 V versus Li at room temperature.     

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…     

Effects of synthesis conditions on the structural and electrochemical properties of layered LiNi1/3Co1/3Mn1/3O2 cathode material via oxalate co-precipitation method

The uniform layered LiNi_1/3Co_1/3Mn_1/3O₂ cathode material for lithium ion batteries was prepared by using (Ni_1/3Co_1/3Mn_1/3)C₂O₄ as precursor synthesized via oxalate co-precipitation method in air. The effects of calcination temperature and time on the structure and electrochemical properties of the LiNi_1/3Co_1/3Mn_1/3O₂ were systemically studied. XRD results revealed that the optimal calcination conditions to prepare the layered LiNi_1/3Co_1/3Mn_1/3O₂ were 950°C for 15 h. Electrochemical measurement showed that the sample prepared under the such conditions has the highest initial discharge capacity of 160.8 mAh/g and the smallest irreversible capacity loss of 13.5% as well as stable cycling performance at a constant current density of 30 mA/g between 2.5 and 4.3 V versus Li at room temperature.     

Synthesis and electrochemical performance of La-doped Li3V2-xLax（PO4）3 cathode materials for lithium batteries

La-doped Li3V2-xLax(PO4)3 (x=0.01,0.02,and 0.03) cathode materials for lithium ion batteries were synthesized by the microwave-assisted carbothermal reduction method (MW-CTR).The structures and properties of the prepared samples were investigated by X-ray diffraction (XRD) and electrochemical measurements.The results showed that all the three Li3V2-xLax(PO4)3 samples had the same monoclinic structures and sharper diffraction peaks of the crystal plane compared with those of the undoped Li3V2(PO4)3.The initial charge/discharge specific capacity,coulomb efficiency,and discharge decay rate of all the three Li3V2-xLax(PO4)3 samples were superior to those of the undoped Li3V2(PO4)3 sample,and the Li3V1.98La0.02(PO4)3 sample exhibited the best features among the three La-doped Li3V2-xLax(PO4)3 samples.Electrochemical impedance spectroscopy (EIS) demonstrated that the Li3V1.98La0.02(PO4)3 sample had a lower charge transfer resistance and a higher Li ion diffusion coefficient compared with the undoped Li3V2(PO4)3 sample.     

Synthesis and electrochemical properties of Li<Subscript>2</Subscript>MnSiO<Subscript>4</Subscript>/C nanoparticles via polyol process

Carbon-coated lithium manganese silicate (Li₂MnSiO₄/C) nanoparticles were synthesized by polyol process. X-ray diffraction (XRD) patterns of the obtained materials exhibit a good fit with that of the Li₂MnSiO₄ phase. Field emission scanning electron microscopy (FESEM) images of the obtained samples show that the particle size is only tens of nanometers. The high resolution transmission electron microscopy (HRTEM) analysis shows that the Li₂MnSiO₄ nanoparticles are surrounded by a very thin film of amorphous carbon. The composite prepared through polyol process shows good performance as cathode materials in lithium cells at room temperature. The charge capacity of the Li₂MnSiO₄/C samples is 219 mAh/g (about 1.3 Li⁺ per unit formula extracted), and the discharge capacity is 132 mAh/g (about 0.8 Li⁺ per unit formula inserted) in the first cycle in the voltage range of 1.5–4.8 V. A good capacity cycling maintenance of 81.8% after 10 cycles was obtained.     

Recycle and synthesis of LiCoO2 from incisors bound of Li-ion batteries

1 Introduction Since the Sony Energytec unveiled the first commercial Li-ion cell[1], the Li-ion battery has become the most attractive energy source for portable electronic products, such as mobile phone, notebook computers. The market for Li-ion batter…     

多元稀土掺杂锂锰氧正极材料的结构及性能表征

采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电池性能测试系统研究了多元稀土掺杂锂锰氧正极材料的相结构、形貌,并对其活化性能、循环稳定性能进行了表征。结果表明:采用Pechini法合成多元稀土掺杂LiMn2O4样品时,只有将掺杂元素的含量严格控制在一定范围内,所合成的LiMn2O4、LiLa0.03Mn1.97O4、LiLa0.012Ce0.012Mn1.976O4、LiLa0.012Nd0.012Mn1.976O4、LiCe0.012Nd0.012Mn1.976O4样品才具有纯尖晶石型LiMn2O4结构。当稀土掺杂元素含量较高时,所合成的LiLa0.015Ce0.015Mn1.97O4、LiLa0.015Nd0.015Mn1.97O4、LiCe0.015Nd0.015Mn1.97O4样品由LiMn2O4相及微量杂质相CeO2、Nd2O3、CeO2+Nd2O3组成。所有样品呈规则的近球形或球形,其粒径范围为0.5～2.8μm。适量的稀土元素掺杂将使LiMn2O4材料的初始容量减小、充放电效率及循环稳定性能增加,LiCe0.012Nd0.012Mn1.976O4样品具有较好的综合电化学性能,其初始容量为123.5mAh/g,经30次循环充放电后的容量为113.2mAh/g,为相同条件下LiMn2O4样品放电容量的1.27倍。     

锂蓄电池正极材料LiV3O8的合成和充放电性能

采用一种液相反应的方法合成LiV3O8化合物 ,首先由NH3·H2 O ,LiOH与V2 O5反应合成含有Li和V的反应前驱产物 ,然后在 180℃的真空环境中进行干燥处理 ,最后将此物质在 5 80℃温度下煅烧成最终产物。采用热重分析试验分析了反应的机理。X射线衍射结果显示得到的物质与用传统合成方法得到的LiV3O8化合物的结构相比 ,在 (10 0 )方向上的衍射峰强度降低很多。在室温、恒电流为 3A/m2 条件下进行充放电试验 ,在 1.8～4.0V范围内 ,首次放电容量达到 2 30Ah/kg ,15周后仍能达到 2 10Ah/kg。     

Effects of Na+ doping on crystalline structure and electrochemical performances of LiNi0.5Mn1.5O4 cathode material

Pristine LiNi_0.5Mn_1.5O₄ and Na-doped Li_0.95Na_0.05Ni_0.5Mn_1.5O₄ cathode materials were synthesized by a simple solid-state method. The effects of Na⁺ doping on the crystalline structure and electrochemical performance of LiNi_0.5Mn_1.5O₄ cathode material were systematically investigated. The samples were characterized by XRD, SEM, FT-IR, CV, EIS and galvanostatic charge/discharge tests. It is found that both pristine and Na-doped samples exhibit secondary agglomerates composed of well-defined octahedral primary particle, but Na⁺ doping decreases the primary particle size to certain extent. Na⁺ doping can effectively inhibit the formation of Li_xNi_1–xO impurity phase, enhance the Ni/Mn disordering degree, decrease the charge-transfer resistance and accelerate the lithium ion diffusion, which are conductive to the rate capability. However, the doped Na⁺ ions tend to occupy 8a Li sites, which forces equal amounts of Li⁺ ions to occupy 16d octahedral sites, making the spinel framework less stable, therefore the cycling stability is not improved obviously after Na⁺ doping.