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1.
Spinel LiMn2O4 is a promising cathode due to its advantages of low-cost, nontoxicity and thermal stability. However, the dissolution of manganese and the phase transformation induce the rapid capacity fade. Surface coating is an effective method to improve its electrochemical performance. In this work, spinel LiMn2O4 modified with perovskite LaCoO3 was prepared using a novel molten salt method. The resulted samples were characterized by X-ray diffraction (XRD), transmission/scanning electron microscopy (TEM/SEM), Fourier transformation infrared (FT-IR), Raman, and X-ray photoelectronic spectroscopy. The content of Mn3+ increased with the LaCoO3 coating accompanied by the increased concentration of oxygen vacancy. LiMn2O4 modified with 2% LaCoO3 shows a higher capacity and cycling stability than others at 0.2 C, while the cathode with 4% LaCoO3 shows the best rate performance at a larger current at 2 and 5 C. This enhanced performance can be attributed to improved interfacial conductivity between the cathode and electrolyte and the protective effects of coating. 相似文献
2.
Ying Li Ting-Feng Yi Xuezhong Li Xueqi Lai Jingjing Pan Ping Cui Yan-Rong Zhu Ying Xie 《Ceramics International》2021,47(13):18732-18742
Li2ZnTi3O8@α-Fe2O3 composites have been successfully prepared by a facile hydrothermal process. Li2ZnTi3O8/α-Fe2O3 composites show similar irregular spherical morphologies like Li2ZnTi3O8 and relatively smaller particle sizes than pristine Li2ZnTi3O8. Among all Li2ZnTi3O8/α-Fe2O3 composites, Li2ZnTi3O8/α-Fe2O3 composite (5 wt%) exhibits the best electrochemical properties. Li2ZnTi3O8/α-Fe2O3 composite (5 wt%) delivers a reversible charge capacity of 184.8 mAh g?1 even at 1000 mA g?1 after 500 cycles, while pristine Li2ZnTi3O8 only delivers a reversible charge capacity of 110.7 mAh g?1. The strong covalent bonds between Li2ZnTi3O8 and α-Fe2O3 will be formed, which is beneficial for the reduction of interfacial energy and thus helpful for the stabilization of the composite. Because of the special synergistic effect of the multi-phase interface, Li2ZnTi3O8/α-Fe2O3 composites not only possess the advantages of single components but also show novel and attractive performances, such as the enhanced ionic conductivity, reduced interfacial charge transfer impedance, improved migration rate of lithium ions, and the enhancement of the rate performance and reversible capacity. The as-prepared Li2ZnTi3O8/α-Fe2O3 composites reveal important potentials as anode materials for next-generation rechargeable Li-ion batteries, and this work also offers an effective strategy to design high performance lithium storage materials for advanced lithium-ion batteries. 相似文献
3.
《Ceramics International》2015,41(7):9018-9023
As one of the most potential negative electrode materials, Na2Ti6O13 is expected to play an important role in the area of high-performance battery. In this work, we have developed an easy, efficient and controllable method to prepare rod-shaped Na2Ti6O13 crystals. This approach utilized a single-source molten salt strategy and only needed to sinter a special precursor synthesized from an aqueous solution containing H3BO3 and (NH4)2TiF6 in presence of sodium salts. The component and shape of precursor crystals can be tuned by adjusting the reagent concentration and reaction temperature. By sintering precursor crystals in air at 900 °C for 30 min, Na2Ti6O13 with high crystallinity and purity can be obtained. X-ray diffraction and scanning electron micrographs results of different sintering times show that the sintering process can be divided into two steps. Firstly, the precursor crystals are converted to TiO2 (anatase) nano-particles and amorphous sodium salts. Subsequently, molten salt reaction occurs between amorphous sodium salts and TiO2 and forms rod-shaped Na2Ti6O13 crystals. 相似文献
4.
Tongzhou Lu Yongzheng Zhang Chun Cheng Yanbin Wang Yongming Zhu 《Frontiers of Chemical Science and Engineering》2020,14(4):595
A facile one-step hydrothermal method has been adopted to directly synthesize the CuCo2S4 material on the surface of Ni foam. Due to the relatively large specific surface area and wide pore size distribution, the CuCo2S4 material not only effectively increases the reactive area, but also accommodates more side reaction products to avoid the difficulty of mass transfer. When evaluated as anode for Li-ion batteries, the CuCo2S4 material exhibits excellent electrochemical performance including high discharge capacity, outstanding cyclic stability and good rate performance. At the current density of 200 mA·g−1, the CuCo2S4 material shows an extremely high initial discharge capacity of 2510 mAh·g−1, and the cycle numbers of the material even reach 83 times when the discharge capacity is reduced to 500 mAh·g−1. Furthermore, the discharge capacity can reach 269 mAh·g−1 at a current of 2000 mA·g−1. More importantly, when the current density comes back to 200 mA·g−1, the discharge capacity could be recovered to 1436 mAh·g−1, suggesting an excellent capacity recovery characteristics. 相似文献
5.
Xueyi Guo Chenlin Yang Jinxiu Chen Qinghua Tian Hongmei Zhang Guoyong Huang 《中国化学工程学报》2021,39(11):247-254
LiNi0.5Mn1.5O4 and LiMn2O4 with novel spinel morphology were synthesized by a hydrothermal and post-calcination process. The synthesized LiMn2O4 particles (5-10 μm) are uniform hexahedron, while the LiNi0.5Mn1.5O4 has spindle-like morphology with the long axis 10-15 μm, short axis 5-8 μm. Both LiMn2O4 and LiNi0.5Mn1.5O4 show high capacity when used as cathode materials for Li-ion batteries. In the voltage range of 2.5-5.5 V at room temperature, the LiNi0.5Mn1.5O4 has a high discharge capacity of 135.04 mA·h·g-1 at 20 mA·g-1, which is close to 147 mA·h·g-1 (theoretical capacity of LiNi0.5Mn1.5O4). The discharge capacity of LiMn2O4 is 131.08 mA·h·g-1 at 20 mA·g-1. Moreover, the LiNi0.5Mn1.5O4 shows a higher capacity retention (76%) compared to that of LiMn2O4 (61%) after 50 cycles. The morphology and structure of LiMn2O4 and LiNi0.5Mn1.5O4 are well kept even after cycling as demonstrated by SEM and XRD on cycled LiMn2O4 and LiNi0.5Mn1.5O4 electrodes. 相似文献
6.
通过均匀沉淀法,以氨水作为络合剂,制备了β-氢氧化镍,经450℃煅烧处理得到纳米氧化镍,通过充放电测试和循环伏安测试研究了该产物作为锂离子电池负极材料的电化学性能.XRD、IR表明,反应产物为纯相,SEM和TEM表明,产物形貌为硬币状的特殊形貌.在放电电位区间0.01~3.0 V vs Li/Li+,0.2C倍率下充放电,初始容量1 050 mAh/g,第2次容量损失35.8%,50次循环后,质量比容量为355 mAh/g,硬币状纳米氧化镍其特殊的形貌具有较大的比表面积,增加了电化学活性点,降低了界面反应的极化,从而提高了NiO电极的电化学性能. 相似文献
7.
锂离子电池正极材料LiMn_2O_4的合成与性能改进 总被引:2,自引:0,他引:2
用传统的高温固相法合成了尖晶石型LiMn_(195)La_(0.05O4)锂离子电池正极材料.通过充-放电测试,其最高容量为117.1mAh/g,经过50次循环后容量为108.4 mAh/g,平均每次循环的容量衰减率为0.15%.利用X射线衍射仪(XRD)和电子扫描电镜(SEM)对材料进行表征.XRD测试结果表明,样品为尖晶石结构;SEM结果表明,样品颗粒形状理想,粒径分布均匀. 相似文献
8.
《Ceramics International》2016,42(15):16557-16562
A novel Li3V2(PO4)3 composite modified with Fe-doping followed by C+SiO2 hybrid layer coating (LVFP/C-Si) is successfully synthesized via an ultrasonic-assisted solid-state method, and characterized by XRD, XPS, TEM, galvanostatic charge/discharge measurements, CV and EIS. This LVFP/C-Si electrode shows a significantly improved electrochemical performance. It presents an initial discharge capacity as high as 170.8 mA h g−1 at 1 C, and even delivers an excellent initial capacity of 153.6 mA h g−1 with capacity retention of 82.3% after 100 cycles at 5 C. The results demonstrate that this novel modification with doping followed by hybrid layer coating is an ideal design to obtain both high capacity and long cycle performance for Li3V2(PO4)3 and other polyanion cathode materials in lithium ion batteries. 相似文献
9.
《Ceramics International》2017,43(3):3393-3400
A modified sol-gel process using ethylene diamine tetraacetic acid and citric acid as bi-components chelating agent was used to prepare Li3.95La0.05Ti4.95Ag0.05O12 (LLTAO). The reactions between raw materials and the possible route of hydrolysis-sintering processes were detailed analyzed and studied. The phases forming mechanism and structure of the colloidal particles, gel and the precursor were also discussed. Interface reaction between chelating agents and precipitate contributes a lot to the products. XRD, SEM, FT-IR, TEM and TG-DSC were used to characterize the intermediates and final powders. The intermediate product of Li and Ti is in nanometer scale, uniformly distributed in precursor. The La3+ and Ag+ co-doping could greatly improve the electrochemical performance of LTO, which reached the capacity of 179, 168, 163, 151, 133, 109 and 76 mA h g−1 at 0.5C, 1C, 2C, 5C, 10C, 20C and 40C discharge rate, respectively. The electrochemical performance of lithium intercalation/extraction was characterized by electrochemical impedance spectroscopy at room temperature. 相似文献
10.
A simple one-step route using gas template method is applied to synthesize macroporous LiNi0.5Mn0.5O2 which is characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Telle (BET) surface area, charge–discharge tests and electrochemical impedance spectroscopy (EIS) measurements. The as-synthesized material shows pure crystalline phase of LiNi0.5Mn0.5O2, while the microstructure is comprised of macrospores ranging from 0.2 to 0.5 μm. The first discharge capacity is of 174 mAh g−1 at 0.1 C rate, which is much higher than that of the material synthesized by the conventional solid state reaction method. Furthermore, the macroporous LiNi0.5Mn0.5O2 material shows remarkable rate capacity and cycle stability, which may be attributed to the shorter lithium ion diffusion distance and better electrolyte penetration. 相似文献
11.
Well-ordered high crystalline LiNi0.5Mn1.5O4 spinel has been readily synthesized by a molten salt method using a mixture of LiCl and LiOH salts. Synthetic variables on the synthesis of LiNi0.5Mn1.5O4, such as synthetic atmosphere, LiCl salt amount, synthetic temperature, and synthetic time, were intensively investigated. X-ray diffraction (XRD) patterns and scanning electron microscopic (SEM) images showed that LiNi0.5Mn1.5O4 synthesized at 900 and 950 °C have cubic spinel structure () with clear octahedral dimension. LiNi0.5Mn1.5O4 spinel phase began to decompose at around 1000 °C accompanied with structural and morphological degradation. LiNi0.5Mn1.5O4 powders synthesized at 900 °C for 3 h delivered an initial discharge capacity of 139 mAh/g with excellent capacity retention rate more than 99% after 50 cycles. 相似文献
12.
13.
用于锂离子电池负极SnO2MCMB复合材料的研究 总被引:3,自引:0,他引:3
以中间相碳微球(MCMB)为核心,用直接沉淀法制备了一种氧化锡颗粒修饰的新型复合碳材料.用X射线衍射和扫描电镜对材料的结构及形貌进行了表征.通过恒流充放电、交流阻抗、循环伏安等测试手段对该材料的嵌脱锂特性进行了研究,循环20周后其比容量仍然保持在360 mAh/g以上.此种复合物可以作为一种锂离子电池新型负极材料. 相似文献
14.
《Ceramics International》2023,49(6):9642-9646
Zirconia nanorods and polyhedral particles were prepared using the molten-salt method. The effects of the LiF dosage on the ZrO2 crystal morphology were studied using XRD combined with Rietveld refinement, FE-SEM combined with EDS, FTIR, Raman spectroscopy, and high-temperature microscopy. The results show that the ZrO2 obtained with LiF is in the monoclinic phase. ZrO2 nanorods were synthesized at low LiF dosages. Polyhedral ZrO2 particles were synthesized, and the ZrO2 crystal planes (100) and (200) were exposed to a high LiF dosage. LiF promoted the dissolution of ZrO2 and was adsorbed onto the ZrO2 crystal surface. This work provides a new strategy for controlling morphology and crystal surface exposure. 相似文献
15.
《Ceramics International》2016,42(13):14855-14861
Pure spherical Li4Ti5O12 spinel material is quickly synthesized via an efficient hydrothermal procedure. The obtained Li4Ti5O12 particle size is about 0.5 µm. The Li4Ti5O12 has an initial discharge capacity of 162.2 mA h g−1 and capacity retention of 97.5% after 100 cycles at a rate of 0.2 C. Then, a 2.5 V and long-lasting Li-ion cell with a LiMn2O4 cathode and a Li4Ti5O12 anode is developed. Electrochemical measurements of the cell indicate that the Li4Ti5O12/LiMn2O4 full cell, with a weight ratio of 1.5 between cathode and anode, exhibits excellent electrochemical performance, delivering a reversible capacity of 130 mA h g−1 at room temperature. The full cell also exhibits outstanding electrochemical performances at high temperature, as it has an initial discharge capacity of 109.6 mA h g−1, along with a capacity retention rate of 88.9% after 100 cycles at 55 °C. 相似文献
16.
17.
Gd and Al co-doped LiMn2-x(GdAl)xO4 (x?=?0, 0.01, 0.02, 0.03, 0.04 and 0.05) materials with spinel structure were synthesized by sol–gel method. Powder X-ray diffraction results confirm the formation of cubic spinel structure and average particle sizes are found to be between 80 and 110?nm from FE-SEM and TEM analysis. Decrease in peak potential difference as a function of doping in Cyclic Voltammetry results establishes enhancement in Li+ intercalation and de-intercalation. Electrochemical Impedance Spectroscopy (EIS) results showed that accumulation of charges on electrode has improved with doping over pristine samples. At a doping of x?=?0.02 charge transfer resistance values were found to be least. First cycle charge–discharge profiles for LiMn1.96(GdAl)0.02O4 shows 139.2?mAh/g discharge capacity over other doped derivatives and pure LiMn2O4 (119.6?mAh/g) in aqueous Li2SO4 electrolyte. Doping of x?=?0.02 exhibit good cycling performance with only a total 4% capacity loss after 30 cycles. 相似文献
18.
The Li–V–O composite (nLi:nV = 1:3.5) was synthesized by a hydrothermal method and post-treated at 300 °C. XRD analysis confirms that the composite is a binary LiV3O8–V2O5 composite system with the formula of 0.8LiV3O8·0.2V2O5. The composite consists of small laminar nanocrystallites with numerous cavities between the stacked laminar nanocrystallites, which can provide good channels for Li+ transfer during charge–discharge cycling. The initial discharge capacities of LiV3O8 and 0.8LiV3O8·0.2V2O5 samples were 276 and 365 mAh/g after 20 cycles, the discharge capacities of the two samples were 197.6 and 304 mAh/g, respectively. Smaller capacity loss indicates that the capacity retention of the composite is superior to that of bare LiV3O8 cathode. 相似文献
19.
《Journal of the European Ceramic Society》2023,43(2):692-699
The focus of lightweight refractory is equivalent volume replacement that uses lower-density raw materials to replace the original high-density raw materials. In this study, we employ porous mullite microspheres (PMM) to replace mullite particles to realize the weight-lighting of mullite–cordierite saggars used to prepare cathode materials for Li-ion batteries.To confirm that lightweight saggars satisfy the quality standards of production, we conducted various tests, including mechanical properties, thermal shock stability and corrosion resistance. Compared with samples with mullite particles, samples with PMM have a comparatively stable material structure and excellent performance. Furthermore, PMM reduce mullite consumption and enhance their resistance to prevent stress shedding in the corrosion process. 相似文献