锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的合成及性能研究

以氢氧化钠为沉淀剂,采用共沉淀法合成了Ni1/3Co1/3Mn1/3(OH)2前驱体,前驱体和LiOH·H2O充分混合高温烧结制备了锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2.采用X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学性能测试对LiNi1/3Co1/3Mn1/3O2正极材料的结构、微观形貌及电化学性能进行了表征.XRD结果表明,所合成的LiNi1/3Co1/3Mn1/3O2物相单一无杂相,具有标准的α-NaFeO2型层状结构.SEM测试显示,颗粒粒度均一,粒径大约在0.5μm,粒径分布窄.以20mA/g电流密度放电,充放电电压在2.8～4.4 V之间,首次放电比容量达到181mAh/g,80次循环之后放电比容量仍然保持在172mAh/g;循环伏安测试显示,LiNi1/3Co1/3Mn1/3O2反应中主要是Ni2 /Ni4 、Co3 /Co4 2个电对在起作用,锰的价态保持不变,起到支撑结构的作用.     

锂离子电池正极材料LiNi1/3 Co1/3 Mn1/3O2的研究进展

介绍了锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的结构,综述了LiNi1/3Co1/3Mn1/3O2的正极材料制备与改性及其电化学性能研究,并对其应用前景进行了展望.     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的制备与表征

以乙酸锂、硝酸镍、硝酸钴和乙酸锰为原料,通过高温固相法,分别采用一次烧结和二次烧结合成了LiNi1/3Co1/3Mn1/3O2。采用X射线衍射、扫描电镜分析以及电化学测试等手段对LiNi1/3Co1/3Mn1/3O2的微观结构、表面形貌和电化学性能进行了研究。结果表明,高温固相法能得到结晶良好的LiNi1/3Co1/3Mn1/3O2,但二次烧结提高了材料的I(003)/I(104)值,降低了c/a值,得到的LiNi1/3Co1/3Mn1/3O2具有更完善的层状结构和更优良的电化学性能。     

LiNi1/3Co1/3Mn1/3O2正极材料的合成及电化学性能研究

通过固相自引发基团置换反应——流变相法制备出层状LiNi1/3Co1/3Mn1/3O2正极材料,研究了不同烧结温度对材料的结构特性、微观形貌以及电化学性能的影响。结果表明,850℃煅烧20h的样品具有最佳的二维层状结构和阳离子有序度,产物颗粒呈球形,分布均匀,平均粒径约250nm。在2.8～4.3V区间,以80mA/g充放电,首次放电比容量为169mAh/g,30次循环后容量保持率为82.6%。将充电截止电压提高至4.4V,材料的前几次放电容量明显提高,以32mA/g充放电,10次循环后的放电比容量为174mAh/g,其后容量衰减加快,循环稳定性变差。     

Synthesis and electrochemical properties of LiNi0.9Co0.1O2 cathode material for lithium secondary battery

Layered LiNi_0.9Co_0.1O₂ cathode material has been successfully synthesized with a calcination time of 0.5 h by a rheological phase reaction method. The obtained powder was characterized by X-ray diffraction (XRD), particle size and particle size distribution, scanning electronic microscope (SEM) and electrochemical measurements. The powder is confirmed to be α-NaFeO₂ structure. Cyclic voltammetry (CV) studies imply that the phase transitions from hexagonal to monoclinic exist during charge–discharge cycling. The LiNi_0.9Co_0.1O₂ cathode demonstrated a good electrochemical property with an initial discharge capacity of 193 mAh g^?1 and capacity retention of 88.6% after 15 cycles.     

层状锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的共沉淀法合成

以Ni(NO3)2·6H2O,Co(NO3)2·6H2O,Mn(CH3COO)2·4H2O,LiOH·H2O为原料,采用NaOH-Na2CO3共沉淀的方法,在空气中合成了三元层状锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2.采用XRD研究了所合成材料的结构.考查了不同烧结温度对材料电化学性能的影响.结果表明,所合成的材料具有典型的α-NaFeO2层状结构特征,900℃下合成的材料具有最优的循环性能,初始放电容量为169.4mAh/g,初次库仑效率为83.2%,且20次循环后,容量保持率达到96.3%.     

Recent development of LiNi1/3Co1/3Mn1/3O2 as cathode material of lithium ion battery

Layered LiNi1/3Co1/3Mn1/3O2, owing to its excellent electrochemical properties, has been used as cathode material for lithium-ion batteries, especially for hybrid electric vehicles. It has many merits such as high capacity, long cycle life, low cost and little harm to environment. Therefore, LiNi1/3Co1/3Mn1/3O2 has become a great concern by scholars on energy and material fields. However, the electronic conductivity and the charge-discharge capacity at high current should be enhanced before any materials modifications. Here, this paper summarizes the main synthetic technologies of LiNi1/3Co1/3Mn1/3O2 in recent years, including synthesis methods, doping, surface coating modification, and the future development trends discussed.     

Synthesis, structure, and some properties of LiNi1/3Co1/3Mn1/3O2

Crystalline LiNi_1/3Co_1/3Mn_1/3O₂ powders have been synthesized by two different procedures, using carbonate coprecipitation from sulfate and nitrate solutions, followed by two-step heat treatment of a mixture of the resultant Ni_1/3Co_1/3Mn_1/3CO₃ precursor and Li₂CO₃ at 500 and 900°C. The powders have been characterized by X-ray diffraction, scanning electron microscopy, and dynamic light scattering. The results demonstrate that the synthesized compounds have a hexagonally ordered, layered structure of the α-NaFeO₂ type. The primary-particle (crystallite) size in the powders is 50 nm and the aggregate size is 150–250 nm. The average size of larger structures (agglomerates) is 11 and 18 μm in the powders prepared via the sulfate and nitrate routes, respectively. The chemical stability of the synthesized powders is shown to depend on the ambient medium. Prolonged storage in air leads to the formation of new, lithium-deficient phases, especially in the case of the powders prepared from nitrate solutions.     

LiFePO4-LiNi1/3Co（1/3）Mn1/3O2混合材料对锂离子电池性能的影响

通过流变相辅助高温固相碳热还原法及碳酸共沉淀法合成了LiFePO4/C复合材料及三元系锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2。将二者按一定比例经强力搅拌混合均匀,获得均匀的共混锂离子电池用正极材料。通过循环充放电测试、交流阻抗测试等研究了混合比例对混合材料电化学性能的影响。实验结果表明LiFePO4与LiNi1/3Co1/3Mn1/3O2通过混合,二者之间产生较强的协同作用,从而实现二者之间的优势互补。并且当混合比例为1∶2时,混合电极具有较好的低温性能、倍率性能及循环稳定性和较高的平均放电平台电压及比能量密度。     

LiNi0.8-x Znx Co0.2 O2的合成及电化学性能研究

掺杂改性和表面修饰的LiNi0.8Co0.2O2是锂电池正极换代候选材料.采用共沉淀法制备了系列LiNi0.8-xZnxCo0.2O2材料,并对其进行X射线衍射(XRD)、扫描电镜(SEM)、循环伏安(CV)、电化学阻抗(EIS)和充放电循环性能(CP)测试分析.恒流循环(0.2C、3.0～4.2V)测试结果显示,Zn的掺入使材料的初始放电比容量有大幅增加,循环性能有所改善.其中LiNi0.78Zn0.02Co0.2O2的首次放电比容量达到206.37 mAh·g-1.第30循环时,放电比容量仍为204.03 mAh·g-1,不可逆容量损失仅为2.34 mAh·g-1,显示了很好的初期循环性能.     

Electrospinning synthesis of novel lithium-rich 0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2 nanotube and its electrochemical performance as cathode of lithium-ion battery

In this study, a lithium-rich layered 0.4Li₂MnO₃·0.6LiNi_1/3Co_1/3Mn_1/3O₂ nanotube cathode synthesized by novel electrospinning is reported, and the effects of temperature on the electrochemical performance and morphologies are investigated. The crystal structure is characterized by X-ray diffraction patterns, and refined by two sets of diffraction data (R-3m and C2/m). Refined crystal structure is 0.4Li₂MnO₃·0.6LiNi_1/3Co_1/3Mn_1/3O₂ composite. The inductively coupled plasma optical emission spectrometer and thermogravimetric and differential scanning calorimetry analysis measurement supply reference to optimize the calcination temperature and heat-treatment time. The morphology is characterized by scanning and highresolution transmission electron microscope techniques, and the micro-nanostructured hollow tubes of Li-rich 0.4Li₂MnO₃·0.6LiNi_1/3Co_1/3Mn_1/3O₂ composite with outer diameter of 200-400 nm and the wall thickness of 50-80 nm are synthesized successfully. The electrochemical evaluation shows that 0.4Li₂MnO₃·0.6LiNi_1/3Co_1/3Mn_1/3O₂ sintered at 800 ℃ for 8 h delivers the highest capacity of the first discharge capacity of 267.7 mAh/g between 2.5 V and 4.8 V at 0.1C and remains 183.3 mAh/g after 50 cycles. The electrospinning method with heat-treatment to get micro-nanostructured lithium-rich cathode shows promising application in lithium-ion batteries with stable electrochemical performance and higher C-rate performance for its shorter Li ions transfer channels and stable designed structure.     

LiNi1-xCoxO2正极材料的合成与电化学性能研究

以Ni1-xCox(OH)2和LiOH·H2O为原料,采用软化学法在空气气氛中于700℃煅烧16h合成出层状LiNi1-xCoxO2正极材料,研究了不同掺钴量对材料的结构和电化学性能的影响,并用XRD及电性能测试考察了所得材料的结构与电化学性能.结果表明:低掺钴量(x≤0.1)时易生成无电化学活性的Li2Ni8O10化合物,高掺钴量(0.2≤x≤0.4)可促进LiNi1-xCoxO2层状结构的生成,有效减少阳离子混排及非化学计量产物的生成.电性能测试结果表明,掺钴量为0.3时的样品LiNi0.7Co0.3O2表现出最好的电化学性能,首次放电容量为172.5mAh/g,40次循环容量保持率达95%,显示较好的循环稳定性.     

LiNi_(0.8)Co_(0.15)Al_(0.05)O_2正极材料的表面包覆改性研究

LiNi_(0.8)Co_(0.15)Al_(0.05)O_2正极材料具有容量高、价格低等优点,被认为是最具发展前景的锂离子电池正极材料之一.但LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料本身存在充放电过程中容量衰减较快、倍率性能差和储存性能差等缺陷,影响了其进一步发展.本文以LiNi_(0.8)Co_(0.15)Al_(0.05)O_2为研究对象,采用共沉淀法制备氢氧化物前驱体,在前驱体的表面包覆一层Ni_(1/3)Co_(1/3)Mn_(1/3)(OH)_2,制备成具有核壳结构的正极材料.通过XRD、SEM、EDX、电化学测试等分析手段,系统地研究了其结构、形貌以及电化学性能.分析表明:包覆改性后,LiNi_(0.8)Co_(0.15)Al_(0.05)O_2正极材料在0.1、0.2、0.5、1 C倍率下,材料的首次充放电比容量分别为167.6,160.1,150.4,138.5 mAh·g~(-1).由0.1到1C,包覆改性前后的正极材料的放电比容量衰减量由34.7 mAh·g~(-1)降为29.1 mAh·g~(-1),容量衰减百分比由22.1%降低到17.4%.综合性能分析认为,包覆改性后电化学性能有一定的改善.     

合成方法对LiNi1/3Co1/3Mn1/3O2电化学性能的影响

采用碳酸盐共沉淀法、草酸盐共沉淀法、溶胶-凝胶法、高温固相法、氢氧化物共沉淀法(pH=10、11、12)制得LiNi1/3Co1/3Mn1/3O2正极材料,通过X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试对样品的结构和性能进行了表征.结果表明,溶胶-凝胶法合成的样品层状结构较完整,阳离子混排程度低,粒径相对较小,颗粒分布均匀;该样品首次放电比容量较高为151 mAh·g-1,循环30次后容量保持率达到93.31％.     

磷酸铝纳米包覆对三元材料性能的影响

为提高三元正极材料的性能,采用纳米AlPO4包覆。并用X射线衍射(XRD),扫描电镜(SEM),透射电镜(TEM)和恒流充放电对包覆和未包覆的材料进行结构表征与性能测试分析。结果表明,AlPO4包覆并没有改变电极材料的晶体结构,仅在电极材料表面形成均匀的包覆层,厚度约为4nm。包覆后的电极材料在3～4.5V的充放电电压范围内,循环性能明显优于未包覆的材料,并且包覆量越高,材料的性能越好。但是包覆量太高会影响其初始容量,研究表明,0.2%的包覆浓度能够提高材料的电化学性能。     

不同合成方法对LiNi1/3Co1/3Mn1/3O2材料电化学性能的影响

通过固相自引发基团置换反应,流变相法和固相自引发基团置换-流变相法3种方法成功制备出LiNi1/3Co1/3Mn1/3O2材料。XRD、SEM和电化学测试表明,固-流法制备的样品具有最稳定的二维层状结构和最小的阳离子混排度及最佳的微观形貌和电化学性能。在2.8～4.3V区间内0.2、0.5、1和2C下的放电比容量分别为185.9、169.9、157.5和134.7mAh/g。0.5C下的循环测试表明,20次循环后电极的放电比容量为143.9mAh/g,容量保持率为84.7%。提高充电截止电压到4.6V,能极大地提高材料的充放电比容量,首次放电比容量为197mAh/g,同时,不可逆容量增大。     

锂离子电池正极材料LiNi1/3 Co1/3Mn1/3 O2的合成及电化学性能的研究

以LiOH·H2O与硫酸混合盐(Mn:Ni:Co=1:1:1)为原料,用液相共沉淀法合成前驱体钴镍锰复合氢氧化物,然后与Li2CO3混合,在不同的焙烧条件下合成LiNi1/3Co1/3Mn1/3O2.通过X射线衍射、DSC-TGA、SEM、充放电测试等手段对材料的物理性能、反应机理及电化学性能进行了研究.结果表明,用此方法合成的LiNi1/3Co1/3Mn1/3-O2具有单一的层状岩盐结构.采用500℃预焙烧,再经800℃焙烧的工艺条件所得产品的X衍射峰尖锐,结构规整,表面微粒较大;充放电测试表明,在4.6～2.5V的初始放电容量达到167.9 mAh/g.     

Boosting the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode materials with Zn3(PO4)2 surface coating

Ni-rich layered oxides have been demonstrated to be promising cathode materials for high-energy–density batteries. However, most of them suffer from sluggish kinetics and structural instability, severely impeding their practical applications. Herein, the surface of LiNi_0.8Co_0.1Mn_0.1O₂ cathode is modified with ionic, conducting zinc phosphate (Zn₃(PO₄)₂) nanolayers. The nanolayers are autogenously formed from the reaction of NH₄H₂PO₄ with ZnO assisted with citric acid. The as-prepared 3 wt% Zn₃(PO₄)₂ coated sample exhibits a first discharge capacity of 203.4 mAh g^-1and excellent capacity retention for 100 cycles. The surface Zn₃(PO₄)₂ nanolayers positively impact the cell performance by scavenging HF and H₂O in the electrolyte, leading to less formation of byproducts on the surface of the cathodes, which lowers the cell resistance and polarization voltage. Our study provides a simple and efficient strategy to design and optimize promising layer-structural cathodes for LIBs.