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1.
Tin‐based oxide Li2SnO3 has been synthesized by a hydrothermal route as negative material for lithium‐ion batteries. The microstructure and electrochemical properties of the as‐synthesized materials were investigated by some characterizations means and electrochemical measurements. The as‐synthesized Li2SnO3 is a porous rod, which is composed of many uniform and regular nano‐flakes with a size of 50–60 nm. Li2SnO3 also displays an electrochemical performance with high capacity and good cycling stability (510.2 mAh g?1 after 50 cycles at a current density of 60 mA g?1 between 0.0 V and 2.0 V verusus Li/Li+). Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

2.
运用共沉淀和元素化学沉积相结合的方法,制备出了具有Ag/C 包覆层的层状富锂固溶体材料Li[Li0.2Mn0.54Ni0.13Co0.13]O2. 通过X 射线衍射(XRD)、场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、恒流充放电、循环伏安(CV),电化学阻抗谱(EIS)和X 射线能量散射谱(EDS)方法,研究了Ag/C 包覆层对Li[Li0.2Mn0.54Ni0.13Co0.13]O2电化学性能的影响. 结果表明,Ag/C 包覆层的厚度约为25 nm,Ag/C 包覆在保持了固溶体材料α-NaFeO2 六方层状晶体结构的前提下,显著地改善了Li[Li0.2Mn0.54Ni0.13Co0.13]O2 的电化学性能. 在2.0-4.8 V(vs Li/Li+)的电压范围内,首次放电(0.05C)容量由242.6 mAh·g-1提高到272.4 mAh·g-1,库仑效率由67.6%升高到77.4%;在0.2C倍率下,30 次循环后,Ag/C 包覆的电极材料容量为222.6 mAh·g-1,比未包覆电极材料的容量高出14.45%;包覆后的电极材料在1C下的容量仍为0.05C下的81.3%. 循环伏安及电化学交流阻抗谱研究表明,Ag/C包覆层抑制了材料在充放电过程中氧的损失,有效降低了Li[Li0.2Mn0.54Ni0.13Co0.13]O2颗粒的界面膜电阻与电化学反应电阻.  相似文献   

3.
应用简单的高温固相烧结法合成了Ti掺杂改性的Li2MnO3材料。电子扫描显微镜、X射线衍射以及X射线光电子能谱分析表明Ti元素取代Mn离子掺入到Li2MnO3晶格中,且掺杂能有效地抑制一次颗粒的团聚。电化学阻抗和恒流充放电测试结果表明,在2.0~4.6 V的电压窗口下,掺杂改性的样品Li2Mn0.9Ti0.03O3的首圈放电比容量达到209 mAh·g-1,库仑效率为99.5%,循环40圈后容量保持率为94%;当电流密度增大到400 mA·g-1时,掺杂改性的样品仍然可以放出120 mAh·g-1比容量,远高于同等电流密度下未掺杂的Li2MnO3原粉的比容量(52 mAh·g-1)。Ti掺杂可有效地改善Li2MnO3的循环稳定性和倍率性能,有利于促进该材料的商业化应用。  相似文献   

4.
应用简单的高温固相烧结法合成了Ti掺杂改性的Li_2MnO_3材料。电子扫描显微镜、X射线衍射以及X射线光电子能谱分析表明Ti元素取代Mn离子掺入到Li_2MnO_3晶格中,且掺杂能有效地抑制一次颗粒的团聚。电化学阻抗和恒流充放电测试结果表明,在2.0~4.6 V的电压窗口下,掺杂改性的样品Li_2Mn_(0.97)Ti_(0.03)O_3的首圈放电比容量达到209 m Ah·g~(-1),库仑效率为99.5%,循环40圈后容量保持率为94%;当电流密度增大到400 m A·g~(-1)时,掺杂改性的样品仍然可以放出120 m Ah·g~(-1)比容量,远高于同等电流密度下未掺杂的Li_2MnO_3原粉的比容量(52 m Ah·g~(-1))。Ti掺杂可有效地改善Li_2MnO_3的循环稳定性和倍率性能,有利于促进该材料的商业化应用。  相似文献   

5.
Sn-doped Li-rich layered oxides of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 have been synthesized via a sol-gel method, and their microstructure and electrochemical performance have been studied. The addition of Sn4+ ions has no distinct influence on the crystal structure of the materials. After doped with an appropriate amount of Sn4+, the electrochemical performance of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 cathode materials is significantly enhanced. The optimal electrochemical performance is obtained at x = 0.01. The Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode delivers a high initial discharge capacity of 268.9 mAh g?1 with an initial coulombic efficiency of 76.5% and a reversible capacity of 199.8 mAh g?1 at 0.1 C with capacity retention of 75.2% after 100 cycles. In addition, the Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode exhibits the superior rate capability with discharge capacities of 239.8, 198.6, 164.4, 133.4, and 88.8 mAh g?1 at 0.2, 0.5, 1, 2, and 5 C, respectively, which are much higher than those of Li1.2Mn0.54Ni0.13Co0.13O2 (196.2, 153.5, 117.5, 92.7, and 43.8 mAh g?1 at 0.2, 0.5, 1, 2, and 5 C, respectively). The substitution of Sn4+ for Mn4+ enlarges the Li+ diffusion channels due to its larger ionic radius compared to Mn4+ and enhances the structural stability of Li-rich oxides, leading to the improved electrochemical performance in the Sn-doped Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials.  相似文献   

6.
Two new quaternary delafossite type oxides with the general formula Ag(Li1/3M2/3)O2, M=Rh, Ir, have been synthesized, and their structures characterized. Based on X-ray and electron diffraction analyses the structural similarity with AgRhO2 delafossite, has been evidenced. The real structures of the quaternary delafossites have been revealed, which has allowed to fully explain the diffuse scattering as observed in X-ray powder diffraction. AgRhO2 is thermally stable up to 1173 K, the behavior of the two quaternary compounds AgLi1/3Rh2/3O2 and AgLi1/3Ir2/3O2 is comparable, and they decompose above 950 and 800 K, respectively. AgRhO2 shows temperature independent paramagnetism, while for the other two an effective magnetic moment of 1.77μB for Ir, and 1.70μB for Rh were determined, applying the Curie-Weiss law. All compounds are semiconducting with activation energies of 4.97 kJ mol−1 (AgLi1/3Rh2/3O2), 11.42 kJ mol−1 (AgLi1/3Ir2/3O2) and 17.58 kJ mol−1 (AgRhO2).  相似文献   

7.
《中国化学快报》2023,34(4):107494
Lithium rich layered oxide (LRLO) has been considered as one of the promising cathodes for lithium-ion batteries (LIBs). The high voltage and large capacity of LRLO depend on Li2MnO3 phase. To ameliorate the electrochemical performance of Li2MnO3, also written as Li(Li1/3Mn2/3)O2, we propose a strategy to substitute Mn4+ and Li+ in Mn/Li transition metal layer with Ti4+, which can stabilize the structure of Li2MnO3 by inhibiting the excessive oxidation of O2? above 4.5 V. More significantly, the unequal-valent substitution brings about the emergence of interlayer Li vacancies, which can promote the Li-ion diffusion based on the enlarged interlayer and increase the capacity by activating the Mn3+/4+ redox. We designed Li0.7[Li1/3Mn2/3]0.7Ti0.3O2 with high interlayer Li vacancies, which presents a high capacity (290 mAh/g at 10 mA/g) and stable cycling performance (84% over 60 cycles at 50 mA/g). We predict that this strategy will be helpful to further improve the electrochemical performance of LRLOs.  相似文献   

8.
The SnO2 sheet/graphite composite was synthesized by a hydrothermal method for high-capacity lithium storage. The microstructures of products were characterized by XRD and FE-SEM. The electrochemical performance of SnO2 sheet/graphite composite was measured by galvanostatic charge/discharge cycling and EIS. The first discharge and charge capacities are 1,072 and 735 mAh g?1 with coulombic efficiency of 68.6 %. After 40 cycles, the reversible discharge capacity is still maintained at 477 mAh g?1. The results show that the SnO2 sheet/graphite composite displays superior Li-battery performance with large reversible capacity and good cyclic performance.  相似文献   

9.
The electrochemical properties of 0.95LiMn0.5Ni0.5O2·0.05Li2TiO3 have been investigated as part of a study of xLiMO2·(1−x)Li2MO3 electrode systems for lithium batteries in which M=Co, Ni, Mn and M=Ti, Zr, Mn. The data indicate that the electrochemically inactive Li2TiO3 component contributes to the stabilization of LiMn0.5Ni0.5O2 electrodes, which improves the coulombic efficiency of Li/xLiMn0.5Ni0.5O2·(1−x)Li2TiO3 cells for x<1. The 0.95LiMn0.5Ni0.5O2·0.05Li2TiO3 electrodes provide a rechargeable capacity of approximately 175 mAh/g at 50 °C when cycled between 4.6 and 2.5 V; there is no indication of spinel formation during electrochemical cycling.  相似文献   

10.
The Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres are firstly prepared and subsequently transferred into the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x sample has a typical α-NaFeO2 layered structure with the existence of Li2MnO3-type integrated component, and the Al2O3 layer is uniformly coated on the surface of the spherical Li-rich Li1.3[Ni0.35Mn0.65]O2+x particles with a thickness of about 4 nm. Importantly, the Al2O3-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% Al2O3-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g?1 at a rate of 0.1 C in the voltage of 2.0–4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% Al2O3-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% Al2O3-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g?1 even at 10 C. Besides, the thin Al2O3 layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li1.3[Ni0.35Mn0.65]O2+x .  相似文献   

11.
LiNi0.80Co0.15Al0.05O2 (NCA) is explored to be applied in a hybrid Li+/Na+ battery for the first time. The cell is constructed with NCA as the positive electrode, sodium metal as the negative electrode, and 1 M NaClO4 solution as the electrolyte. It is found that during electrochemical cycling both Na+ and Li+ ions are reversibly intercalated into/de-intercalated from NCA crystal lattice. The detailed electrochemical process is systematically investigated by inductively coupled plasma-optical emission spectrometry, ex situ X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The NCA cathode can deliver initially a high capacity up to 174 mAh g?1 and 95% coulombic efficiency under 0.1 C (1 C?=?120 mA g?1) current rate between 1.5–4.1 V. It also shows excellent rate capability that reaches 92 mAh g?1 at 10 C. Furthermore, this hybrid battery displays superior long-term cycle life with a capacity retention of 81% after 300 cycles in the voltage range from 2.0 to 4.0 V, offering a promising application in energy storage.  相似文献   

12.
A hierarchical fibrous SnO2/carbon nanocomposite composed of fine SnO2 nanocrystallites immobilized as a thin layer on a carbon nanofiber surface was synthesized employing natural cellulose substance as both scaffold and carbon source. It was achieved by calcination/carbonization of the as‐deposited SnO2‐gel/cellulose hybrid in an argon atmosphere. As being employed as an anode material for lithium‐ion batteries, the porous structures, small SnO2 crystallite sizes, and the carbon buffering matrix possessed by the nanocomposite facilitate the electrode–electrolyte contact, promote the electron transfer and Li+ diffusion, and relieve the severe volume change and aggregation of the active particles during the charge/discharge cycles. Hence, the nanocomposite showed high reversible capacity, significant cycling stability, and rate capability that are superior to the nanotubular SnO2 and SnO2 sol–gel powder counter materials. For such a composite with 27.8 wt % SnO2 content and 346.4 m2 g?1 specific surface area, a capacity of 623 mAh g?1 was delivered after 120 cycles at 0.2 C. Further coating of the SnO2/carbon nanofibers with an additional carbon layer resulted in an improved cycling stability and rate performance.  相似文献   

13.
Biomimetic straw-like bundles of Co-doped Fe2O3 (SCF), with Co2+ incorporated into the lattice of α-Fe2O3, was fabricated through a cost-effective hydrothermal process and used as the anode material for lithium-ion batteries (LIBs). The SCF exhibited ultrahigh initial discharge specific capacity (1760.7 mA h−1 g−1 at 200 mA g−1) and cycling stability (with the capacity retention of 1268.3 mA h−1 g−1 after 350 cycles at 200 mA g−1). In addition, a superior rate capacity of 376.1 mA h−1 g−1 was obtained at a high current density of 4000 mA g−1. The remarkable electrochemical lithium storage of SCF is attributed to the Co-doping, which increases the unit cell volume and affects the whole structure. It makes the Li+ insertion–extraction process more flexible. Meanwhile, the distinctive straw-like bundle structure can accelerate Li ion diffusion and alleviate the huge volume expansion upon cycling.  相似文献   

14.
LiNi1/3Co1/3Mn1/3O2 cathode materials for the application of lithium ion batteries were synthesized by carbonate co-precipitation routine using different ammonium salt as a complexant. The structures and morphologies of the precursor [Ni1/3Co1/3Mn1/3]CO3 and LiNi1/3Co1/3Mn1/3O2 were investigated through X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were examined using charge/discharge cycling and cyclic voltammogram tests. The results revealed that the microscopic structures, particle size distribution, and the morphology properties of the precursor and electrochemical performance of LiNi1/3Co1/3Mn1/3O2 were primarily dependent on the complexant. Among all as-prepared LiNi1/3Co1/3Mn1/3O2 cathode materials, the sample prepared from Na2CO3–NH4HCO3 routine using NH4HCO3 as the complexant showed the smallest irreversible capacity of 19.5 mAh g−1 and highest discharge capacity of 178.4 mAh g−1 at the first cycle as well as stable cycling performance (98.7% of the initial capacity was retained after 50 cycles) at 0.1 C (20 mA g−1) in the voltage range of 2.5–4.4 V vs. Li+/Li. Moreover, it delivered high discharge capacity of over 135 mAh g−1 at 5 C (1,000 mA g−1).  相似文献   

15.
P2‐type Na2/3Ni1/3Mn2/3O2 was synthesized by a controlled co‐precipitation method followed by a high‐temperature solid‐state reaction and was used as a cathode material for a sodium‐ion battery (SIB). The electrochemical behavior of this layered material was studied and an initial discharge capacity of 151.8 mA h g?1 was achieved in the voltage range of 1.5–3.75 V versus Na+/Na. The retained discharge capacity was found to be 123.5 mA h g?1 after charging/discharging 50 cycles, approximately 81.4 % of the initial discharge capacity. In situ X‐ray diffraction analysis was used to investigate the sodium insertion and extraction mechanism and clearly revealed the reversible structural changes of the P2‐Na2/3Ni1/3Mn2/3O2 and no emergence of the O2‐Ni1/3Mn2/3O2 phase during the cycling test, which is important for designing stable and high‐performance SIB cathode materials.  相似文献   

16.
使用Ge4+、Sn4+作为掺杂离子, 通过高温固相法制备四价阳离子掺杂改性的尖晶石LiMn2O4材料. X射线衍射(XRD)和扫描电子显微镜(SEM)分析表明, Ge4+离子取代尖晶石中Mn4+离子形成了LiMn2-xGexO4 (x=0.02,0.04, 0.06)固溶体; 而Sn4+离子则以SnO2的形式存在于尖晶石LiMn2O4的颗粒表面. Ge4+离子掺入到尖晶石LiMn2O4材料中, 抑制了锂离子在尖晶石中的有序化排列, 提高了尖晶石LiMn2O4的结构稳定性; 而在尖晶石颗粒表面的SnO2可以减少电解液中酸的含量, 抑制酸对LiMn2O4活性材料的侵蚀. 恒电流充放电测试表明, 两种离子改性后材料的容量保持率均有较大幅度的提升, 有利于促进尖晶石型LiMn2O4锂离子电池正极材料的商业化生产.  相似文献   

17.
The Li2ZnTi3-xMoxO8 (x = 0, 0.05, 0.1 and 0.15) anode materials are successfully synthesized through a simple solid-state method, and few Li2MoO4 phase can be found in Li2ZnTi3-xMoxO8 (x = 0.1 and 0.15). All samples are composed of nanocrystalline particles and irregular micron-sized particles with a relatively uniform particle size of 100–200 nm Li2ZnTi2.9Mo0.1O8 shows the best electrochemical properties among all samples. The Li2ZnTi2.9Mo0.1O8 delivers a charge/discharge capacity of 188.1/188.2 mA h/g at 1 A/g after 400 cycles, but the corresponding capacity of pristine Li2ZnTi3O8 is only 104.5 (102.2) mA h/g. The Mo6+ doping enhances the reversible capacity, rate performance, and cycling stability of Li2ZnTi3O8, especially at large current densities. The improved electrochemical performance of Li2ZnTi3-xMoxO8 can be ascribed to the enhanced electrical conductivity, improved intercalation/de-intercalation reversibility of Li ions, increased lithium-ion diffusion coefficients, and reduced charge-transfer resistance. This work provides an effective strategy to construct high-performance anode materials for advanced lithium-ion battery; this effective design strategy may be used to enhance the reversible specific capacity, and rate the performance and cycle stability of other insertion-host anode materials.  相似文献   

18.
By dissolving crystalline V2O5 in hydrogen peroxide and drying at elevated temperature, the V2O5 xerogel was obtained. Its electrochemical behaviour was examined in aqueous solution of LiNO3 by both cyclic voltammetry and galvanostatic charging/discharging cycling. Peak-to-peak potential separation observed at the cyclovoltammograms indicated fast Li+ intercalation/deintercalation reactions. Initial discharge capacity amounted to 69 mAhg?1, and after 100 charging/discharging cycles, capacity fade amounted to 11% only. This presents a remarkable improvement in comparison with the behaviour of crystalline, vanadium oxide based, lithium intercalates in aqueous electrolytes.  相似文献   

19.
Lithium‐rich layer‐structured oxides xLi2MnO3? (1?x)LiMO2 (0<x<1, M=Mn, Ni, Co, etc.) are interesting and potential cathode materials for high energy‐density lithium ion batteries. However, the characteristic charge compensation contributed by O2? in Li2MnO3 leads to the evolution of oxygen during the initial Li+ ion extraction at high voltage and voltage fading in subsequent cycling, resulting in a safety hazard and poor cycling performance of the battery. Molybdenum substitution was performed in this work to provide another electron donor and to enhance the electrochemical activity of Li2MnO3‐based cathode materials. X‐ray diffraction and adsorption studies indicated that Mo5+ substitution expands the unit cell in the crystal lattice and weakens the Li?O and Mn?O bonds, as well as enhancing the activity of Li2MnO3 by lowering its delithiation potential and suppressing the release of oxygen. In addition, the chemical environment of O2? ions in molybdenum‐substituted Li2MnO3 is more reversible than in the unsubstituted sample during cycling. Therefore molybdenum substitution is expected to improve the performances of the Li2MnO3‐based lithium‐rich cathode materials.  相似文献   

20.
采用碳酸盐共沉淀法通过调节NH3·H2O用量来实现可控制备超高倍率纳米结构LiNi1/3Co1/3Mn1/3O2正极材料。NH3·H2O用量会对颗粒的形貌、粒径、晶体结构以及材料电化学性能产生较大的影响。X射线衍射(XRD)分析和扫描电镜(SEM)结果表明,随着NH3·H2O用量的降低,一次颗粒形貌由纳米片状逐渐过渡到纳米球状,且nNH3·H2O:(nNi+nCo+nMn)=1:2样品晶体层状结构最完善、Li+/Ni2+阳离子混排程度最低。电化学性能测试结果也证实了nNH3·H2O:(nNi+nCo+nMn)=1:2样品具有最优异的循环稳定性和超高倍率性能。具体而言,在2.7~4.3 V,1C下循环300次后的放电比容量为119 mAh·g-1,容量保持率为81%,中值电压基本无衰减(保持率为97%)。在100C(18 Ah·g-1)的超高倍率下,放电比容量还能达到56 mAh·g-1,具有应用于高功率型锂离子电池的前景。此NH3·H2O比例值对于共沉淀法制备其他高倍率、高容量的正/负极氧化物材料具有一定的工艺参考价值。  相似文献   

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