电解液添加剂PHS对LiNi0.8Mn0.1Co0.1O2锂离子电池性能的影响

以2-苯基-1-基1H-咪唑-1-磺酸酯(PHS)作为电解液添加剂,用于LiNi0.8Mn0.1Co0.1O2(NCM811)/石墨软包电池中.充放电测试和电化学测量的结果表明,PHS的添加可以提高NCM811/石墨软包电池的常温、低温和高温循环性能,令电池能够在-20～60°C的温度范围内工作,极大地提升了锂离子电池...     

层状锂离子电池正极材料LiNi0.8Co0.1Mn0.1O2的制备及性能

采用共沉淀法得到前驱体Ni0.8Co0.1Mn0.1(OH)2,利用前驱体与LiOH×H2O的高温固相反应得到高振实密度的锂离子电池层状正极材料LiNi0.8Co0.1Mn0.1O2 (2.3~2.5 g/cm3). 初步探讨了合成条件对材料电化学性能的影响. 通过X射线衍射(XRD)、扫描电镜(SEM)、热重-差热分析(TG/DTG)以及恒电流充放电测试对合成的样品进行了测试和表征. 结果表明,在750℃、氧气气氛下合成的材料具有较好的电化学性能. 通过XRD分析可知该材料为典型的六方晶系a-NaFeO2结构;SEM测试发现产物粒子是由500~800 nm的一次小晶粒堆积形成的二次类球形粒子. 电化学测试表明,其首次放电容量和库仑效率分别为168.6 mA×h/g和90.5%, 20次循环后容量为161.7 mA×h/g,保持率达到95.9%,是一种具有应用前景的新型锂离子电池正极材料.     

锂离子电池高镍三元正极材料LiNi0.8Co0.1Mn0.1O2的性能研究

富镍正极材料(LiNi0.8Co0.1Mn0.1O2)具有高容量的优点,是锂离子电池正极材料最有潜力的材料之一。为确定最佳合成条件,本工作研究了合成温度对材料性能的影响,并详细分析了材料电化学性能衰减的原因以及循环过程中材料结构的变化。采用热重/差示扫描量热法(TG/DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(HRTEM)、能谱仪(EDS)、X射线光电子能谱(XPS)等手段对合成的正极材料进行了物化表征,并对其电化学性能进行测试。结果表明,在低温段500℃保温4 h,高温段750℃保温14 h合成的正极材料NCM750在0.2 C首次放电比容量为186.2 mAh/g,首次充放电效率为82.5%,1 C放电比容量为185.1 mAh/g,100次循环后仍有175.2 mAh/g,容量保持率为95.2%。在此条件下合成的材料具有结构稳定,粒径均匀,电化学性能优异等优点,本工作对富镍正极材料的合成及结构变化进行研究,有助于加深对材料的了解。     

掺锂量对锂离子电池正极材料LiNi1／3Co1／3Mn1／3O2的影响研究

采用共沉淀法,分别控制锂过量3％、5％和7％,制备了LiNi1／3Co1／3Mn1／3O2的前驱体,把真空干燥后的前驱体置于空气气氛下的马弗炉中,控制煅烧温度为900℃,对该前驱体进行煅烧。对所得样品进行XRD、SEM表征、电性能测试,根据XRD图、SEM图和充放电循环曲线,探讨了不同掺锂量对产物的影响,最后得到过锂3％条件下煅烧的材料形貌和电化学性能最佳的结论。     

基于水热/溶剂热法制备不同形貌LiNi0.8Co0.1Mn0.1O2 锂离子电池正极材料

基于水热/溶剂热法制备LiNi_0.8Co_0.1Mn_0.1O₂电极材料,以镍、钴、锰乙酸盐为原料,以六亚甲基四胺为沉淀剂、水或乙醇为溶剂,通过调节溶剂组分控制Ni_0.8Co_0.1Mn_0.1（OH）₂（NCM）的成核与生长速率,从而合成两种形貌不同的Ni_0.8Co_0.1Mn_0.1（OH）₂前驱体,再经过混锂煅烧获得LiNi_0.8Co_0.1Mn_0.1O₂正极材料,研究比较了其电化学性能。以水为溶剂通过水热法合成的前驱体样品呈现出由一次片状颗粒紧密堆积组成的长方体状二次颗粒形貌,经混锂煅烧得到的产物表现出较高的放电比容量,在0.5C倍率下首次放电比容量可达到189.70 mA·h/g,循环200次容量保持率为69.72%。以乙醇为溶剂通过溶剂热法合成得到球形二次颗粒前驱体,最终得到的产物具有多孔球形结构,表现出了优异的循环性能,0.5C首次放电比容量为178.65 mA·h/g,循环200次容量保持率仍高达94.55%。     

LiNio.5Mn1.5O4/Li4Ti5O12全电池的制备及电化学性能研究

以5V高电压LiNi0.5Mn1 5O4为正极材料,高安全性Li4Ti5O12为负极材料制备了LiNi0.5Mn1.5O4/Li4Ti5O12全电池,重点研究了正负极容量配比对电池电化学性能的影响.其中正极容量过量40％的电池具有最好的倍率和循环性能,在0.5 C电流下,P/N=1.4的电池的最高放电比容量为164.1 mAh·g-1,循环200次的容量保持率为88％;在2C电流下,P/N=1.4的电池的最高放电比容量为135.2 mAh·g-1,循环740次的容量保持率为91.1％.P/N=1.4的电池良好的倍率和循环性能与其内阻较小、电池极化较小等因素有关.     

正极材料LiNi0.8Co0.1Mn0.1O2的合成工艺优化及电化学性能

采用高温固相法合成锂离子电池富镍三元材料LiNi_0.8Co_0.1Mn_0.1O₂,对其工艺条件进行优化,对产物进行X射线衍射（XRD（,扫描电镜（SEM（以及电化学性能分析。结果表明：在氧气气氛下,锂与金属元素摩尔比为1.05:1、烧结时间15 h、烧结温度750℃为最佳合成工艺条件。按最佳工艺合成的样品在1C首次放电容量高达174.9 mA·h·g^-1,50次循环后比容量为158.5 mA·h·g^-1,容量保持率为90.62%,表现出良好的循环稳定性。XRD和SEM表征表明,在氧气气氛下烧结的样品有良好的层状结构,阳离子混排程度小,具有较好的类球形,粒径均匀分布在10~20 μm。循环伏安（CV（和电化学阻抗（EIS（结果表明,工艺条件的优化有助于提高正极材料的电化学性能。     

电解液对锂离子电池性能的影响

锂离子电池的性能与电解液有着密切的关系。电解液的组成主要是:有机溶剂、锂盐、添加剂。本文综述了电解液组成对锂离子电池电化学性能的影响规律;探讨了电解液量对锂离子电池性能的影响以及不同正极材料锂离子电池对电解液量的需求。     

Li(Ni,Co,Mn)O_2三元材料的性能研究

近年来锂离子电池对能量密度的要求越来越高,同时也希望有较低的成本和良好的性能。采用532型Li(Ni,Co,Mn)O2三元材料设计成2200 mAh的电池,并对电池的电性能与安全性能进行了相关的测试。结果表明,采用该材料制作的电池克容量发挥可达160 mAh/g,具有较好的循环性能、倍率性能与安全性能。     

锂离子电池正极材料LiNi0.8Co0.2O2的研究

低成本、高比容量的LiNi0.8Co0.2O2是取代已商品化锂电池正极材料LiCoO2的候选材料。用工业原料,通过共沉淀法(pH=11 2±0 05)合成了β Ni0.8Co0.2(OH)2,将其和LiOH·H2O混合,在空气中先后于650℃和750℃烧结8h和20h,制得具有良好层状结构的LiNi0.8Co0.2O2。用合成的材料制备电池,在0 2C、3 0～4 1V进行充放电实验,其放电平台在3 8V以上,首次放电容量超过170mA·h/g,10次循环后,放电容量还能保持在164mA·h/g左右,且库仑效率达到96%以上。     

Influence of lithium difluorophosphate additive on the high voltage LiNi0.8Co0.1Mn0.1O2/graphite battery

Lithium-ion batteries (LIBs) possessing high energy densities are driven by the growing demands of electric vehicles (EVs) and hybrid electric vehicles (HEVs). One of the most effective strategies to improve the energy density of LIBs is to enlarge the charge cut-off voltage via a lithium salt additive for the conventional electrolyte system. Herein, lithium difluorophosphate (LIDFP) is employed to optimize and reconstruct the composition of the structure and interface for both cathode and anode, which can effectively restrain the oxidation decomposition of electrolyte as well as refrain the dissolve out of transition metals. The LiNi_0.8Co_0.1Mn_0.1O₂ (LNCM811)/graphite pouch cell with 1 wt% LIDFP in electrolyte delivers a discharge capacity retention of 91.3% at a high voltage of 4.4 V over 100 cycles, which is higher than the 82.0% of that without LIDFP additive. Additionally, the remaining capacity of LNCM811/C battery with 1 wt% LIDFP additive which is left at 60 °C for 14 days is 85.2%, and the recovery capacity is 93.3%. The LIDFP-containing electrolyte demonstrates a great application future for the LiBs operating under the high-voltage condition and high-temperature storage performance.     

Effect of micron sized particle on the electrochemical properties of nickel-rich LiNi0.8Co0.1Mn0.1O2 cathode materials

Particle size plays an important role in the electrochemical properties of cathode materials for lithium-ion battery, and the sizes of cathode powders are often designed to specific scales to obtain desired rate capacity, cyclic stability, etc. Nano-sized or micron-sized primary/secondary particles were both reported to be helpful to heighten the electrochemical properties of the same material system. However, the relationship between particle size and electrochemical properties of Ni-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM-811) has not been discussed in detail. Here, we prepared the pristine NCM-811 powders with various micro-sized particles by using solid state reaction, and investigated the influence of particle size on the electrochemical properties of typical NCM-811 cathode material, to clarify the importance of size effect. The result indicates that pristine NCM-811 cathode powders with D₅₀ = 7.7 μm displayed the best initial discharge specific capacity (224.5 and 169.1 mA h/g at 1/20 C and 1 C rate, respectively) and retention capacity (71.0% at 1 C rate) after 100th cycling at room temperature. The mutual acting mechanism in terms of layered structure, cation mixing degree, polarization state, charge-transfer resistance, and the diffusion ability of lithium-ion was confirmed by XRD, XPS, CV and EIS analyses, respectively.     

Li2ZrO3包覆LiNi0.8Co0.1Mn0.1O2的复合材料及其电化学性能

以Zr（NO₃）₄·5H₂O和CH₃COOLi·2H₂O为原料,采用湿化学法,将Li₂ZrO₃包覆在LiNi_0.8Co_0.1Mn_0.1O₂锂离子电池正极材料的表面,研究Li₂ZrO₃不同包覆比例对LiNi_0.8Co_0.1Mn_0.1O₂电化学性能的影响。SEM、TEM、EDS谱图分析表明,Li₂ZrO₃层均匀地包覆在LiNi_0.8Co_0.1Mn_0.1O₂表面,其厚度约为8 nm。与纯相相比,1%（质量分数） Li₂ZrO₃包覆的LiNi_0.8Co_0.1Mn_0.1O₂复合材料在1.0 C下首次放电比容量为184.7 mA·h·g^-1、100次循环之后放电比容量为169.5 mA·h·g^-1,其容量保持率达到91.77%,表现出良好的循环稳定性。循环伏安（CV）和电化学阻抗（EIS）测试结果表明,Li₂ZrO₃包覆层抑制了正极材料与电解液之间的副反应,减小了材料在循环过程中的电荷转移阻抗,从而提高了材料的电化学性能。     

Effects of Al2O3 and LiAlO2 Co-coating on electrochemical properties of LiNi0.8Co0.1Mn0.1O2 cathode materials

Lithium-ion batteries are widely used in aerospace, power vehicles, portable electronic devices and other fields because of their environmental friendliness, rechargeable cycle and high energy density. The nickel-cobalt-manganese ternary materials with high nickel has high specific discharge capacity and is regarded as one of the most promising cathode materials. However, with the increase of the number of cycles, the cycle performance becomes worse and the specific capacity decays sharply. In this work, Al₂O₃ and LiAlO₂ were coated on the surface of NCM811 by combining ball milling mixing and solid-phase synthesis to prepare the AL-NCM811 cathode material. The coating thickness formed by Al₂O₃ and LiAlO₂ was 10–70 nm, which effectively improves the cycle stability and rate performance of NCM811 material. When charged and discharged at 0.1C, the first discharge specific capacity and capacity retention rate after 100 cycles of 0.5AL-NCM811 were 196.26 mAh/g and 96.47%, respectively, while those of NCM811 were only 193.78 mAh/g and 72.18%, respectively. When the current density was 5.0C, the discharge specific capacity of 0.5AL-NCM811(139.16 mAh/g) was 55.368 mAh/g higher than that of NCM811(83.80 mAh/g).     

Enhanced electrochemical performance of LiNi0.8Co0.1Mn0.1O2 via titanium and boron co-doping

Titanium and boron are simultaneously introduced into LiNi_0.8Co_0.1Mn_0.1O₂ to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti⁴⁺ ion replaces Li⁺ ion and reduces the cation mixing; B³⁺ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO₆] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g^-1 at 1 C and 155.5 mAh·g^-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi_0.8Co_0.1Mn_0.1O_2.     

Enhancing high-potential stability of Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode with PrF3 coating

It is still a huge challenge to improve the safety and stability of Ni-rich (LiNi_0.8Co_0.1Mn_0.1O₂) cathode materials at elevated potential. Herein, the PrF₃ layer is employed to protect LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) via a simple wet chemical process. It was confirmed by XRD, HR-SEM, TEM, EDS, and XPS tests that PrF₃ is evenly covered throughout the surface of NCM811 without affecting the particle size and surface morphology. In particular, 1 wt% PrF₃ coated NCM811 exhibits excellent stability and rate capability with the capacity retention of 86.3% after 100 cycles at 1 C under a cut-off potential of 4.3 V, while the retention of pristine one is only 73.8%. Moreover, the capacity retention of 1 wt% PrF₃ coated samples enhances from 74.5% to 88.5% after 50 cycles at 1 C under higher cut-off voltage of 4.6 V. The superior performance for coated samples can be attributed to the fact that PrF₃ can effectively isolate the active material and the electrolyte from HF corrosion, and at the same time, reduce the generation of micro-cracks on the surface during prolonged cycles. Furthermore, as a physical barrier, PrF₃ alleviates the dissolution of transition metals in the electrolyte largely. These results suggest that the stability of NCM811 can be greatly upgraded at high voltage by PrF₃ coating.     

Synthesis and characterization of mono-dispersion LiNi0.8Co0.1Mn0.1O2 micrometer particles for lithium-ion batteries

LiNi_0.8Co_0.1Mn_0.1O₂ cathode material for lithium-ion battery exhibits high capacity, but it suffers from interfacial side reactions and structural/thermodynamic instability, which leads to capacity reduction and safety problems. Cubic brick (Ni_0.8Co_0.1Mn_0.1)C₂O₄·2H₂O particles with micron size are synthesized by co-precipitation method. The oxalic precursor is sintered with lithium hydroxide to obtain cubic mono-dispersion LiNi_0.8Co_0.1Mn_0.1O₂ micrometer particles. Structural stability, cycling performance, rate capability and compacting density of the cubic mono-dispersion material are investigated. Conventional spherical and irregular mono-dispersion LiNi_0.8Co_0.1Mn_0.1O₂ are also prepared for comparison. The results reveal that the cubic mono-dispersion LiNi_0.8Co_0.1Mn_0.1O₂ dramatically enhances the structural stability and cycling performance at a little cost of capacity and rate capability.