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PVP-functionalized nanometre scale metal oxide coatings for cathode materials: successful application to LiMn2O4 spinel nanoparticles 总被引:1,自引:0,他引:1
PVP functionalized metal oxide coatings on spinel nanoparticles demonstrated significantly improved rate characteristics under extensive cycling at 65 degrees C and exhibited over 100% improved capacity retention compared to the bare counterpart. 相似文献
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Xiang Ming He Jian Jun Li Yan Cai Yaowu Wang Jierong Ying Changyin Jiang Chunrong Wan 《Journal of Solid State Electrochemistry》2005,9(6):438-444
A novel process is proposed for synthesis of spinel LiMn2O4 with spherical particles from the inexpensive materials MnSO4, NH4HCO3, and NH3H2O. The successful preparation started with carefully controlled crystallization of MnCO3, leading to particles of spherical shape and high tap density. Thermal decomposition of MnCO3 was investigated by both DTA and TG analysis and XRD analysis of products. A precursor of product, spherical Mn2O3, was then obtained by heating MnCO3. A mixture of Mn2O3 and Li2CO3 was then sintered to produce LiMn2O4 with retention of spherical particle shape. It was found that if lithium was in stoichiometric excess of 5% in the calcination of spinel LiMn2O4, the product had the largest initial specific capacity. In this way spherical particles of spinel LiMn2O4 were of excellent fluidity and dispersivity, and had a tap density as high as 1.9 g cm–3 and an initial discharge capacity reaching 125 mAh g–1. When surface-doped with cobalt in a 0.01 Co/Mn mole ratio, although the initial discharge capacity decreased to 118 mAh g–1, the 100th cycle capacity retention reached 92.4% at 25°C. Even at 55°C the initial discharge capacity reached 113 mAh g–1 and the 50th cycle capacity retention was in excess of 83.8%. 相似文献
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尖晶石LiMn_2O_4的表面改性研究 总被引:10,自引:0,他引:10
采用溶胶_凝胶法合成尖晶石LiMn2 O4 ,并以LiCoO2 对其进行包覆 ,用XRD、SEM、EPMA等方法对修饰的尖晶石结构和性能进行研究 .结果表明 ,经包覆的LiMn2 O4 在 70 0℃焙烧 10h所得的晶粒是表层富含Co的立方尖晶石 ,而且晶粒中Co3+的含量呈现出从表到里递减的梯度分布 .以该材料作锂离子电池正极 ,虽初始容量稍有降低 ,但能有效地降低Mn2 +在电解质中的溶解 ,而且对Jahn_Teller效应有一定的抑制作用 ,包覆的LiMn2 O4 尖晶石正极材料比未包覆的有更好的循环性能 相似文献
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Peng Zhongdong Wang Gaofeng Cao Yanbing Zhang Zhijian Du Ke Hu Guorong 《Journal of Solid State Electrochemistry》2016,20(10):2865-2871
Journal of Solid State Electrochemistry - Li2MnO3 coated spinel lithium manganese oxide (LiMn2O4) materials have been successfully synthesized by a sol-gel method. Scanning electron microscopy... 相似文献
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Bowei Ju Xianyou Wang Chun Wu Qiliang Wei Xiukang Yang Hongbo Shu Yansong Bai 《Journal of Solid State Electrochemistry》2014,18(1):115-123
The Y2O3 nano-film is coated on the surface of the spherical spinel LiMn2O4 by precipitation method and subsequent heat treatment at 550 °C for 5 h in air. The structure and performance of the bare LiMn2O4 and Y2O3-coated LiMn2O4 are characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive analysis X-ray spectroscopy, galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. It has been found that the addition of Y2O3 does not change the bulk structure of LiMn2O4, and the thickness of the Y2O3 coating layer is approximate to 3.0 nm. The 1 wt% Y2O3-coated LiMn2O4 electrode reveals excellent cycling performance with 80.3 % capacity retention after 500 cycles at 1 C at 25 °C. When cycling at elevated temperature 55 °C, the as-prepared sample still shows 76.7 % capacity retention after 500 cycles. These remarkable improvements indicate that thin Y2O3 coating on the surface of LiMn2O4 is an effective way to improve the electrochemistry performance. Besides, the suppression of Mn dissolution into the electrolyte via the Y2O3 coating layer can be accounted for the improved performances. 相似文献
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Wen-Jia Zhou Shu-Juan Bao Yan-Yu Liang Ben-Lin He Hu-Lin Li 《Journal of Solid State Electrochemistry》2006,10(5):277-282
Pure-phase and well-crystallized spinel LiMn2O4 powders were successfully synthesized by a simple rheological phase method. The thermal behavior and structure properties
of the powders prepared by the rheological phase method compared with the solid-state reaction were investigated by thermogravimetry,
powder X-ray diffraction , scanning electron microscopy and transmission electron microscopy. According to the results of
the electrochemical tests, it is obvious that the sample resulting from the rheological phase method shows higher discharge
capacity and better cycling stability than one formed in the solid-state reaction. The cyclic voltammogram and columbic efficiency
curves also confirm that the product by the rheological phase method has a good cycling performance due to its fine cubic
spinel structure and morphology. 相似文献
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Yingping Wang Xianyou Wang Shunyi Yang Hongbo Shu Qiliang Wei Qiang Wu Yansong Bai Benan Hu 《Journal of Solid State Electrochemistry》2012,16(9):2913-2920
Spinel LiMn2O4 cathode materials were coated with 1.0, 3.0 and 5.0?wt.% of MgF2 by precipitation, followed by heat treatment at 400?°C for 5?h in air. The effects of MgF2 coating on the structural and electrochemical properties of LiMn2O4 cathodes were investigated using XRD, SEM, and electrochemical tests. XRD and SEM results show that no significant bulk structural differences are observed between the coated and pristine LiMn2O4. The charge–discharge tests show that the discharge capacity of LiMn2O4 decreases slightly, but the cyclability of LiMn2O4 is clearly improved when the amount of the MgF2 coated was increased to 3.0?wt.%. The 3.0?wt.% MgF2-coated LiMn2O4 exhibits capacity retention of 80.1 and 76.7 % after 100 cycles at room temperature (25?°C) and elevated temperature (55?°C) at a rate of 1?C, respectively, much higher than those of the bare LiMn2O4 (70.1 and 61.6 %). The improvement of electrochemical performance is attributed to the suppression of Mn dissolution into the electrolyte via the MgF2 coating layer. 相似文献
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采用LiNO3和MnO2为原料,在650℃下制备了尖晶石型的LiMn2O4.通过X射线衍射、扫描电子显微镜、热重分析和电化学性能测试,发现该化合物具有很高的放电比容量和较好的循环性能,首次放电比容量可达到122 mA·h/g.并对循环性能衰减的各种因素进行了讨论. 相似文献
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Wei Qiliang Wang Xianyou Yang Xiukang Shu Hongbo Ju Bowei Hu Benan Song Yunfeng 《Journal of Solid State Electrochemistry》2012,16(11):3651-3659
Journal of Solid State Electrochemistry - The spinel LiMn2O4 samples for lithium-ion battery have been synthesized through one-step solid-state method using four different polymorphs of MnO2, e.g.,... 相似文献
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G. G. Wang J. M. Wang W. Q. Mao H. B. Shao J. Q. Zhang C. N. Cao 《Journal of Solid State Electrochemistry》2005,9(7):524-530
LiMn2O4 powder for lithium-ion batteries was prepared by a precipitation method, and the effects of calcination temperature on the physical properties and electrochemical performance of the samples were investigated by various methods. The results of X-ray diffraction (XRD) showed that the lattice parameter (a) and the unit cell volume (v) decrease with the increasing calcination temperature, and the LiMn2O4 sample calcined at 750°C has smaller particle size and higher crystallinity than other samples. The results of the electrochemical experiments showed that the sample calcined at 750°C has larger peak currents, higher initial capacity, and better cycling capability, because of its lower charge-transfer resistance and larger diffusion coefficient of Li+ ions than those of other samples. 相似文献
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Brett Ammundsen Gary R. Burns Ali Amran Stig E. Friberg 《Journal of Sol-Gel Science and Technology》1994,2(1-3):341-346
A preparative technique based on the gelation of a microemulsion has provided a means of homogeneously dispersing high concentrations of metal oxide precursor salts through silica gel. The microstructures and compositions of gels containing combinations of lithium and manganese nitrate, and of the multiphase materials obtained by firing to a range of temperatures up to 1000°C, have been established. Formation of the mixed metal oxide spinel phase LiMn2O4 within a silica support has been obtained for systems comprising from 10 to 30 wt% metal nitrate by heating to temperatures between 500 and 700°C. 相似文献
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Lilong Xiong Youlong Xu Cheng Zhang Zhengwei Zhang Jiebin Li 《Journal of Solid State Electrochemistry》2011,15(6):1263-1269
Ti-doped spinel LiMn2O4 is synthesized by solid-state reaction. The X-ray photoelectron spectroscopy and X-ray diffraction analysis indicate that
the structure of the doped sample is Li( Mn3 + Mn1 - x 4 + Tix4 + )O4 {\hbox{Li}}\left( {{\hbox{M}}{{\hbox{n}}^{3 + }}{\hbox{Mn}}_{1 - x\,}^{4 + }{\hbox{Ti}}_x^{4 + }} \right){\hbox{O}}{}_4 . The first principle-based calculation shows that the lattice energy increases as Ti doping content increases, which indicates
that Ti doping reinforces the stability of the spinel structure. The galvanostatic charge–discharge results show that the
doped sample LiMn1.97Ti0.03O4 exhibits maximum discharge capacity of 135.7 mAh g−1 (C/2 rate). Moreover, after 70 cycles, the capacity retention of LiMn1.97Ti0.03O4 is 95.0% while the undoped sample LiMn2O4 shows only 84.6% retention under the same condition. Additionally, as charge–discharge rate increases to 12C, the doped sample
delivers the capacity of 107 mAh g−1, which is much higher than that of the undoped sample of only 82 mAh g−1. The significantly enhanced capacity retention and rate capability are attributed to the more stable spinel structure, higher
ion diffusion coefficient, and lower charge transfer resistance of the Ti-doped spinel. 相似文献
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Xian Ming Wu Shang Chen Fa Ren Mai Jun Hai Zhao Chang An Li Wei Liu 《Journal of Solid State Electrochemistry》2013,17(3):707-711
LiMn2O4 thin films were prepared by spin coating through intermediate amorphous layer route (IALR) and intermediate crystallized layer route (ICLR). The phase identification, surface morphology, and electrochemical properties of the films prepared by different crystallization routes were studied by X-ray diffraction, scanning electron microscopy, and galvanostatic charge–discharge experiments. The results show that both films prepared by different crystallization routes are homogeneous and crack free. Compared with the film prepared by IALR, the film prepared by ICLR shows smaller grain size and is smoother and denser. The LiMn2O4 film prepared by ICLR delivers the specific capacity of 39.8 μAh?cm?2?μm?1, which is higher than 35.6 μAh?cm?2?μm?1 for the one prepared by IALR. The capacity loss of the film prepared by ICLR after being cycled 100 times is 3.4 %, which is smaller than that of 5.5 % for the film prepared by IALR. The film prepared by ICLR shows higher specific capacity and better cycling behavior than the one prepared by IALR. 相似文献
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The spinel thin films of LiMn2O4 and LiSn0.0125Mn1.975O4 prepared by RF magnetron sputtering were studied with focusing on structural and electrochemical properties. The LiSn0.0125Mn1.975O4 thin films showed the superior properties, i.e., a high capacity retention of 94% at the current rate of 5 C after 90 cycles, due to the increase in Mn valence and the decrease in oxygen deficiency. The larger oxygen deficiency in undoped LiMn2O4 thin films was confirmed by the increased lattice volume and structural degeneration. 相似文献
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ZrO2 macroporous materials with well-ordered structures were prepared using nano-ZrO2 particles as the building materials and polystyrene spheres as the organic templates. A well-dispersed nano-ZrO2 suspension with a narrow particle size distribution was prepared by deagglomeration of as-received nano-ZrO2 powders via ultrasonication, and then centrifugation was performed to remove agglomerated bigger particles. Negatively charged polystyrene spheres were uniformly coated with positively charged nano-ZrO2 particles by means of electrostatic attraction at pH 4. Green samples were prepared by slip casting from colloidally stable suspension of nano-ZrO2 coated polystyrene spheres. ZrO2 macroporous materials with well-ordered microstructure derived from the nano-ZrO2 coated polystyrene spheres. 相似文献
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《Electrochemistry communications》2003,5(11):940-945
LiMn2O4 spinel coated sonochemically with MgO was studied as an active mass in composite cathodes in standard Li electrolyte solutions for Li-ion batteries at 60 °C. Solutions comprising 1 M LiPF6 in a mixture of ethylene, dimethyl, and diethyl carbonates (EC–DMC–DEC; 2:2:1) were used. It was possible to obtain LiMn2O4 particles fully covered by porous magnesia films that allow a free transport of Li-ions. Electrodes comprising LiMn2O4, modified by MgO showed a higher capacity retention compared to the electrodes comprising an uncoated active mass, specially at elevated temperatures. We suggest that the presence of an MgO film on the surface of the LiMn2O4 particles, reduces the detrimental effect of HF contamination present in LiPF6 solutions, reduces the electrodes’ impedance and improves their kinetics. 相似文献
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Jian Xie Cheng-Yue Sun Tie-Jun Zhu Gao-Shao Cao Xin-Bing Zhao Shi-Chao Zhang 《Journal of Solid State Electrochemistry》2013,17(10):2589-2594
LiMn2O4 microcubes with a size of 10–15 μm have been synthesized by a facile self-templating route starting from cubic MnCO3. The LiMn2O4 microcubes exhibit a hierarchical structure, where the cubes are stacked from parallel plates with a thickness of 200 nm, where each plate is composed of interconnected nanoparticles with a size of around 200 nm. The cubic LiMn2O4 shows excellent rate capability and high-rate cycling stability. At 10 C, it can yield a discharge capacity of 108 mAh g?1. A discharge capacity of 88 mAh g?1 can be retained after 100 cycles at 10 C. The excellent electrochemical performance makes it a promising cathode for high-power Li-ion batteries. 相似文献
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Journal of Thermal Analysis and Calorimetry - A series of LiMn2O4 samples with nominal Li/Mn molar ratio=1/2 has been synthesized at 700 and 750°C by the ceramic procedure from Mn2O3 and... 相似文献