Surface modification of LiNi<Subscript>1/3</Subscript>Co<Subscript>1/3</Subscript>Mn<Subscript>1/3</Subscript>O<Subscript>2</Subscript> with Cr<Subscript>2</Subscript>O<Subscript>3</Subscript> for lithium ion batteries

Cr 2 O 3-coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials were synthesized by a novel method. The structure and electrochemical properties of prepared cathode materials were measured using X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The measured results indicate that surface coating with 1.0 wt% Cr 2 O 3 does not affect the LiNi 1/3 Co 1/3 Mn 1/3 O 2 crystal structure (α-NaFeO 2 ) of the cathode material compared to the pristine material, the surfaces of LiNi 1/3 Co 1/3 Mn 1/3 O 2 samples are covered with Cr 2 O 3 well, and the LiNi 1/3 Co 1/3 Mn 1/3 O 2 material coated with Cr 2 O 3 has better electrochemical performance under a high cutoff voltage of 4.5 V. Moreover, at room temperature, the initial discharging capacity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 material coated with 1.0 wt.% Cr 2 O 3 at 0.5C reaches 169 mAh·g 1 and the capacity retention is 83.1% after 30 cycles, while that of the bare LiNi 1/3 Co 1/3 Mn 1/3 O 2 is only 160.8 mAh·g 1 and 72.5%. Finally, the coated samples are found to display the improved electrochemical performance, which is mainly attributed to the suppression of the charge-transfer resistance at the interface between the cathode and the electrolyte.     

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 performances of LiNi0.6Co0.2Mn0.2O2 cathode materials

LiNi_0.6Co_0.2Mn_0.2O₂ was prepared from LiOH·H₂O and MCO₃ (M=Ni, Co, Mn) by co-precipitation and subsequent heating. XRD, SEM and electrochemical measurements were used to examine the structure, morphology and electrochemical characteristics, respectively. LiNi_0.6Co_0.2Mn_0.2O₂ samples show excellent electrochemical performances. The optimum sintering temperature and sintering time are 850 °C and 20 h, respectively. The LiNi_0.6Co_0.2Mn_0.2O₂ shows the discharge capacity of 148 mA·h/g in the range of 3.0?4.3 V at the first cycle, and the discharge capacity remains 136 mA·h/g after 30 cycles. The carbonate co-precipitation method is suitable for the preparation of LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials with good electrochemical performance for lithium ion batteries.     

丝网印刷氧化石墨烯对锂离子电池LiNi1/3Co1/3Mn1/3O2 三元正极的改性及性能影响

通过丝网印刷方法,在由LiNi_1/3Co_1/3Mn_1/3O₂、导电添加剂和聚偏氟乙烯制成的电极表面涂覆了一层薄薄的氧化石墨烯。在充电截止电压为4.3 V的条件下进行了循环性能和倍率性能测试。结果表明：未改性电极在恒电流充放电测试中容量下降且极化增加,而包覆改性后电极的容量衰减程度和极化增加速度降低。这是由于氧化石墨烯涂层抑制了LiNi_1/3Co_1/3Mn_1/3O₂电极和电解质之间的部分副反应,使得改性电极的循环稳定性和倍率性能显著提高,为提升LiNi_1/3Co_1/3Mn_1/3O₂电极性能提供了一种环境友好且非常有效的方法。     

Effect of a surface treatment for LiNi<Subscript>1/3</Subscript>Co<Subscript>1/3</Subscript>Mn<Subscript>1/3</Subscript>O<Subscript>2</Subscript> cathode material in lithium secondary batteries

LiNi_1/3Co_1/3Mn_1/3O₂ cathode material was surface-treated to improve its electrochemical performance. Al₂O₃ nanoparticles were coated onto the surface of LiNi_1/3Co_1/3Mn_1/3O₂ powder using a sol-gel method. The as-prepared Al₂O₃ nano-particle was identified as the cubic structure of Al₂O₃. XRD showed that the LiNi_1/3Co_1/3Mn_1/3O₂ structure was not affected by the Al₂O₃ coating. With a coating of 3 wt.% Al₂O₃ on LiNi_1/3Co_1/3Mn_1/3O₂, the cyclic-life performance and rate capability were improved. However, heavier coatings (5 wt.%) on LiNi_1/3Co_1/3Mn_1/3O₂ resulted in a considerable decrease of the discharge capacity and rate capability. The thermal stability of LiNi_1/3Co_1/3Mn_1/3O₂ materials was greatly improved by the 3 wt.% Al₂O₃ coating.     

Effects of ZrO2 Coating on LiNi1/3Mn1/3Co1/3O2 Particle with Microwave Pyrolysis

In this paper, ZrO₂-coated LiNi_1/3Mn_1/3Co_1/3O₂ is successfully prepared by the microwave pyrolysis method. The structure and electrochemical properties of the ZrO₂-coated LiNi_1/3Co_1/3Mn_1/3O₂ are investigated using x-ray diffraction, AC impedance, and charge/discharge tests, indicating that the lattice structure of LiNi_1/3Co_1/3Mn_1/3O₂ is unchanged after the coating but the cycling stability is improved. As the coating amount is 2 wt.%, initial capacity of the coated LiNi_1/3Co_1/3Mn_1/3O₂ decreases slightly. However, the cycling stability increases remarkably over the cut-off voltages of 2.75~4.3 V and the capacity retention reaches 93.1% after 50 cycles. Electrochemical impedance spectra results show that the increase of charge transfer resistance during cycling is suppressed significantly by coating with ZrO₂.     

Preparation and electrochemical properties of LiNi1/3Co1/3Mn1/3O2–PPy composites cathode materials for lithium-ion battery

Layered LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized by co-precipitation method, and a series of polypyrrole–LiNi_1/3Co_1/3Mn_1/3O₂ composites were then prepared by polymerizing pyrrole monomers on the surface of LiNi_1/3Co_1/3Mn_1/3O₂. The bare sample and composites were subjected to analysis and characterization by the techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical properties of the composites were investigated with galvanostatic charge–discharge test and AC impedance measurements, which show that the formed coats of polypyrrole (PPy) significantly decrease the charge-transfer resistance of LiNi_1/3Co_1/3Mn_1/3O₂. And the composite containing 2.0 wt% PPy exhibits a good electrochemical performance, its specific discharge capacity is 182 mAh g^?1 at 0.1C rate and voltage limits of 2.8–4.6 V, while the capacity of the bare sample is only 134 mAh g^?1.     

Synthesis and characterization of layered Li（Ni1/3Mn1/3CO1/3）O2 cathode materials by spray-drying method

Spherical Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1 000 ℃ for 10 h. The impacts of different sintering temperatures on the structure and electrochemical performances of Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 were compared by means of X-ray diffractometry(XRD), scanning electron microscopy(SEM), and charge/discharge test as cathode materials for lithium ion batteries. The experimental results show that the spherical morphology of the spray-dried powers maintains during the subsequent heat treatment and the specific capacity increases with rising sintering temperature. When the sintering temperature rises up to 900 ℃ , Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 attains a reversible capacity of 153 mA·h/g between 3.00 and 4.35 V at 0.2C rate with excellent cyclability.     

Enhanced cycling stability of La modified LiNi0.8–xCo0.1Mn0.1LaxO2 for Li-ion battery

A series of layered LiNi_0.8–xCo_0.1Mn_0.1La_xO₂ (x=0, 0.01, 0.03) cathode materials were synthesized by combining co-precipitation and high temperature solid state reaction to investigate the effect of La-doping on LiNi_0.8Co_0.1Mn_0.1O₂. A new phase La₂Li_0.5Co_0.5O₄ was observed by XRD, and the content of the new phase could be determined by Retiveld refinement and calculation. The cycle stability of the material is obviously increased from 74.3% to 95.2% after La-doping, while the initial capacity exhibits a decline trend from 202 mA·h/g to 192 mA·h/g. The enhanced cycle stability comes from both of the decrease of impurity and the protection of newly formed La₂Li_0.5Co_0.5O₄, which prevents the electrolytic corrosion to the active material. The CV measurement confirms that La-doped material exhibits better reversibility compared with the pristine material.     

Enhanced cycling stability of Mg–F co-modified LiNi0.6Co0.2Mn0.2–yMgyO2–zFz for lithium-ion batteries

The layered LiNi_0.6Co_0.2Mn_0.2–yMg_yO_2–zF_z (0≤y≤0.12, 0≤z≤0.08) cathode materials were synthesized by combining co-precipitation method and high temperature solid-state reaction, with the help of the ball milling, to investigate the effects of F–Mg doping on LiNi_0.6Co_0.2Mn_0.2O₂. Compared with previous studies, this doping treatment provides substantially improved electrochemical performance in terms of initial coulombic efficiency and cycle performance. The LiNi_0.6Co_0.2Mn_0.11Mg_0.09O_1.96F_0.04 electrode delivers an high capacity retention of 98.6% during the first cycle and a discharge capacity of 189.7 mA·h/g (2.8–4.4 V at 0.2C), with the capacity retention of 96.3% after 100 cycles. And electrochemical impedance spectroscopy(EIS) results show that Mg–F co-doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance. It is demonstrated that LiNi_0.6Co_0.2Mn_0.11Mg_0.09O_1.96F_0.04 is a promising cathode material for lithium-ion batteries for excellent electrochemical properties.     

Pseudocapacitance properties of AC/LiNi1/3Co1/3Mn1/3O2 asymmetric supercapacitor in aqueous electrolyte

NH₂NH₂·H₂O which was used as controlling agent was applied to prepare the precursor Ni_1/3Co_1/3Mn_1/3(OH)₂ in the hydroxide co-precipitation method. The precursor was used to synthesize LiNi_1/3Co_1/3Mn_1/3O₂. The samples were characterized by XRD, XPS and SEM. It has been found that sintered sample at 800 °C for 16 h is considered as the optimal synthetic condition. The LiNi_1/3Co_1/3Mn_1/3O₂ was used as positive electrode and the activated carbon as negative electrode of the asymmetric supercapacitor. The electrochemical capacitance performance was tested by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge. The results indicate that species of aqueous electrolyte, current density, scan rate and potential limit, etc. have influence on the capacitance property of AC/LiNi_1/3Co_1/3Mn_1/3O₂ supercapacitor. The initial discharge specific capacitance of 298 F g^?1 was obtained in 1 mol L^?1 Li₂SO₄ solution within potential range 0–1.4 V at the current density of 100 mA g^?1 and was cut down less than 0.058 F g^?1 per cycling period in 1000 cycles. The asymmetric supercapacitor exhibited a good cycling performance.     

AlF3包覆锂离子电池正极材料Li1.2(Mn0.54Ni0.16Co0.08)O2的制备、表征及电化学性能（英文）

采用溶胶-凝胶法合成锂离子电池正极材料Li1.2(Mn0.54Ni0.16Co0.08)O2,并用Al F3对这种材料进行表面包覆改性。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨率透射电子显微镜(HRTEM)等表征材料的结构和形貌。结果表明,合成的Li1.2(Mn0.54Ni0.16Co0.08)O2具有典型的层状α-Na Fe O2结构,AlF3均匀包覆在Li1.2(Mn0.54Ni0.16Co0.08)O2材料表面,包覆层厚度为5~7 nm。电化学测试表明,包覆Al F3后材料的电化学性能得到提高,在1C倍率下,包覆的AlF3材料的首次放电容量为208.2 m A·h/g,50次循环后容量保持率为72.4%,而未包覆AlF3的材料的首次放电容量和容量保持率分别为191.7 m A·h/g和51.6%。     

模拟废旧锂离子电池湿法冶金浸出液再生铝掺杂LiNi0.5Co0.2Mn0.3O2正极材料

采用共沉淀法制备均相Al掺杂的LiNi0.5Co0.2Mn0.3O2正极材料,以利用Al对再生镍钴锰(NCM)正极材料的正面改性作用,并改善锂离子电池回收过程中繁琐和高成本的除杂过程.当浸出液中的Al3+含量为过渡金属(Ni、Co和Mn)总量的1％(摩尔分数)时,制备的Al掺杂NCM正极材料中晶格氧和Ni2+的浓度增加...     

Preparation and electrochemical performance of nitrogen-doped carbon-coated Bi2Mn4O10 anode materials for lithium-ion batteries

To inhibit rapid capacity attenuation of Bi₂Mn₄O₁₀ anode material in high-energy lithium-ion batteries, a novel high-purity anode composite material Bi₂Mn₄O₁₀/ECP-N (ECP-N: N-doped Ketjen black) was prepared via an uncomplicated ball milling method. The as-synthesized Bi₂Mn₄O₁₀/ECP-N composite demonstrated a great reversible specific capacity of 576.2 mA·h/g after 100 cycles at 0.2C with a large capacity retention of 75%. However, the capacity retention of individual Bi₂Mn₄O₁₀ was only 27%. Even at 3C, a superior rate capacity of 236.1 mA·h/g was retained. Those remarkable electrochemical performances could give the credit to the introduction of ECP-N, which not only effectively improves the specific surface area to buffer volume expansion and enhances conductivity and wettability of composites but also accelerates the ion transfer and the reversible conversion reaction.     

Effects of chromium doping on performance of LiNi0.5Mn1.5O4 cathode material

In order to improve the cycle and rate performance of LiNi_0.5Mn_1.5O₄, LiCr_2YNi_0.5–YMn_1.5–YO₄ (0≤Y≤0.15) particles were synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi_0.5Mn_1.5O₄ on the structures and electrochemical properties were investigated. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge-discharge test and electrochemical impedance spectrum (EIS). The results indicate that the LiCr_2YNi_0.5–YMn_1.5–YO₄ possess a spinel structure and small particle size, and LiCr_0.2Ni_0.4Mn_1.4O₄ exhibits the best cyclic and rate performance. It can deliver discharge capacities of 143 and 104 mA·h/g at 1C and 10C, respectively, with good capacity retention of 96.5% at 1C after 50 cycles.     

一步双修饰策略提高富镍层状氧化物正极材料的电化学性能（英文）

提出一种从表面到体相的一步整体改性策略,同步合成Nb掺杂和LiNbO₃包覆的LiNi_0.83Co_0.12Mn_0.05O₂(NCM)正极材料。LiNbO₃包覆层可以调控界面并促进锂离子扩散;更强的Nb—O键能有效抑制Li⁺/Ni²⁺阳离子混排,提高晶体结构稳定性,从而有助于缓解Li⁺脱出/嵌入过程中晶格参数的各向异性变化。结果表明:双修饰材料表现出较好的结构稳定性和优异的电化学性能。最佳样品NCM-Nb2在2.7～4.3 V之间以1C循环100次后,容量保持率为90.78%,而原始样品容量保持率仅为67.90%;同时,在10C下具有149.1 mA·h/g的更高倍率性能,这些结果突显了一步双修饰策略协同提高富镍层状氧化物正极材料电化学性能的可行性。     

微乳液法制备锂离子电池用 ZnMn2O4/Mn3O4亚微米棒及其转化反应机理

采用油包水微乳液法再经煅烧制备分级ZnMn2O4/Mn3O4复合亚微米棒.ZnMn2O4/Mn3O4电极在550次连续放电/充电循环中,在500 mA/g充放电电流条件下,其比容量从440 mA·h/g增加到910 mA·h/g,并在100 mA/g下提供1276 mA·h/g的超高比容量,远高于ZnMn2O4或Mn3...     

不同锂源对高温固相法制备NCM811正极材料储锂性能的影响

采用4种不同的锂盐(LiOH.H₂O、Li₂CO₃、LiNO₃、CH₃COOLi),以高温固相法制备了LiNi_0.8Co_0.1Mn_0.1O₂正极材料。利用X射线粉末衍射(XRD)和场发射电子显微镜(FESEM)对所制LiNi_0.8Co_0.1Mn_0.1O₂材料的微观结构进行了表征,发现所有合成的LiNi_0.8Co_0.1Mn_0.1O₂样品尺寸均为微米级大小,具有层状结构(R-3m空间群)。电化学测试结果表明采用不同锂源制备的LiNi_0.8Co_0.1Mn_0.1O₂样品的电化学性能差别很大。其中采用LiOH?H₂O为锂源,经500 °C预烧结6 h后,在800 °C下烧结16 h获得的样品锂镍混排程度最低,电化学性能最佳。例如,在0.1 C(1 C=180 mA/g)倍率下其可逆比容量高达206.2 mA.h/g,在10 C大倍率下,其可逆比容量仍保持有80.9 mA.h/g;在0.5 C倍率下100次充放电循环过程中,最高放电比容量为176.2 mA.h/g,平均放电比容量为140.1 mA.h/g。动力学及电极稳定性分析发现,LiOH?H₂O制备的样品的电化学可逆性最好,Li^₊扩散系数最大,充放电循环过程中结构稳定性最好。     

Effect of lithium content on electrochemical property of Li1+x(Mn0.6Ni0.2Co0.2)1-xO2 (0≤x≤0.3) composite cathode materials for rechargeable lithium-ion batteries

In order to confirm the optimal Li content of Li-rich Mn-based cathode materials (a fixed mole ratio of Mn to Ni to Co is 0.6:0.2:0.2), Li_1+x(Mn_0.6Ni_0.2Co_0.2)_1-xO₂ (x=0, 0.1, 0.2, 0.3) composites were obtained, which had a typical layered structure with and C2/m space group observed from X-ray powder diffraction (XRD). Electron microscopy micrograph (SEM) reveals that the particle sizes in the range of 0.4-1.1 μm increase with an increase of x value. Li_1.2(Mn_0.6Ni_0.2Co_0.2)_0.8O₂ sample delivers a larger initial discharge capacity of 275.7 mA·h/g at the current density of 20 mA/g in the potential range of 2.0–4.8 V, while Li_1.1(Mn_0.6Ni_0.2Co_0.2)_0.9O₂ shows a better cycle performance with a capacity retention of 93.8% at 0.2C after 50 cycles, showing better reaction kinetics of lithium ion insertion and extraction.     

Facile synthesis of high capacity P2-type Na2/3Fe1/2Mn1/2O2 cathode material for sodium-ion batteries

P2-type Na_2/3Fe_1/2Mn_1/2O₂ was synthesized by a facile sol−gel method, and the effect of calcination temperature on the structure, morphology and electrochemical performance of samples was investigated. The results show that the sample obtained at 900 °C is pure P2-type Na_2/3Fe_1/2Mn_1/2O₂ phase with good crystallization, which consists of hexagon plate-shaped particles with the size and thickness of 2−4 µm and 200−400 nm, respectively. The sample exhibits an initial specific discharge capacity of 243 mA·h/g at a current density of 26 mA/g with good cycling stability. The high specific capacity indicates that P2-type Na_2/3Fe_1/2Mn_1/2O₂ is a promising cathode material for sodium- ion batteries.