共查询到20条相似文献,搜索用时 15 毫秒
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以二茂铁为铁源,石油渣油为碳源,通过加压热解和空气氧化制备了碳包覆空心Fe3O4纳米粒子。采用X射线衍射(XRD)、透射电镜(TEM)以及高倍透射电镜(HRTEM)等测试方法对样品的形貌和结构进行表征。采用恒流充放电和交流阻抗方法测试碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能。在电流密度为0.2mA/cm2时,首次放电比容量高达1294.7mAh/g,30次循环之后其放电比容量为392.1mAh/g;电流密度为1mA/cm2时,首次放电比容量为216.3mAh/g,30次循环之后其放电比容量为113mAh/g。 相似文献
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以Ni(CH3COO)2·4H2O和Mn(CH3COO)2·4H2O为原料,分别在400、500℃分解3、7h得到镍锰复合氧化物前驱体,再与锂源Li2CO3混匀,在800℃煅烧12h,600℃退火24h得到LiNi0.5Mn1.5O4正极材料。XRD、SEM、EIS和恒流充放电测试结果表明,在400℃、7h制备的前驱体与Li2CO3合成的LiNi0.5Mn1.5O4性能最佳。室温下以0.1C倍率充放电,首次放电比容量达到141.5mAh/g,循环30次后容量保持率为98.55%;以1C倍率充放电,首次放电比容量为120.34mAh/g,循环30次后放电比容量为112.09mAh/g。 相似文献
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采用湿法球磨-喷雾干燥法制备了多孔球形锂离子电池Li2MnSiO4/C复合正极材料。X射线衍射(XRD)表明合成的Li2MnSiO4具有正交结构,属于Pmn21空间群。扫描电镜(SEM)和透射电镜(TEM)显示粉体复合材料为直径10μm左右的球形团簇,由100nm左右的颗粒堆积而成,颗粒表面包覆1层大约3nm的碳层。电化学测试表明,在0.05和0.5C倍率下,Li2MnSiO4/C样品的首次放电容量分别为153和110mAh/g,50次循环后容量分别保持80%和66%。 相似文献
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Jin Cheng Renchao Che Chongyun Liang Jiwei Liu Min Wang Junjie Xu 《Nano Research》2014,7(7):1043-1053
Large specific surface area is critical for Li4Ti5O12 to achieve good rate capacity and cycling stability, since it can increase the contact area between electrolyte/ electrode and shorten the transport paths for electrons and lithium ions. In this study, hierarchical hollow Li4Ti5O12 urchin-like microspheres with ultra-high specific surface area of over 140 m2·g^-1 and diameter more than 500 nm have been successfully synthesized by combining the versatile sol-gel process and a hydrothermal reaction, and exhibit excellent electrochemical performance with a high specific capacity of 120 mA-h.g-1 at 20 C and long cycling stability of 〈 2% decay after 100 cycles. Ex situ electron energy loss spectroscopy (EELS) analysis of Li4Ti5O12 microspheres at different charge-discharge stages indicates that only a fraction of the TP* ions are reduced to Ti3+ and a phase transformation occurs whereby the spinel phase Li4TisO12 is converted into the rock-salt phase Li7Ti5O12. Even after 100 cycles, the oxidation-reduction reaction between Ti3+ and Ti4+ can be carried out much more effectively on the surface of Li4Ti5O12 nanosheets than on commercially available Li4Ti5O12 particles. All the results suggest that these Li4Ti5O12 microspheres may be attractive candidate anode materials for lithium ion batteries. 相似文献
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Achmad Yanuar Maulana Jungwook Song Da Won Lee Chae Eun Lee Jongsik Kim 《材料科学技术学报》2021,85(26):184-193
Sodium-ion batteries(SIBs)are considered one of the most promising energy storage systems for replac-ing lithium-ion batteries because of the high abundance and low cost of sodium.Iron oxyfluoride(FeOF)is a promising conversion-based cathode material for SIBs because of its high theoretical capacity of about 855 mA h g-1,low-cost chemical compositions,and its lower sensitivity to the size of charged carrier ions.However,the poor electrical conductivity and ionic diffusion of FeOF result in a low rate capability and cyclability.In this work,FeOF nanoparticles wrapped by graphitic carbon layers were synthesized using abietic or maleopimaric acid as both the carbon source and organic ligand.In addition,the mor-phology of the FeOF particles was gradually controlled from rod to spherical shapes,simply depending on the rosin acids.The FeOF nanoparticles prepared with maleopimaric acid showed a large reversible discharge capacity of 356.7 mA h g-1 with a fading rate of 0.21%per cycle after 100 cycles at a current density of 100 mA g-1 and an excellent rate capability. 相似文献
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橄榄石型结构LiFePO4因其结构特征和潜在的低成本而有望成为下一代锂离子电池正极材料。但是要使LiFePO4商业化必须开发出适于规模化生产高性能LiFePO4正极材料的工艺。本文在综合分析LiFePO4制备方法、导电性改善及填充密度提高途径的基础上,认为可借鉴Ni-MH电池正极材料球形Ni(OH)2制备技术发展经验,从理论上深入研究LiFePO4的形成过程,通过控制橄榄石型结构LiFePO4材料的结晶度、晶粒大小及形貌、元素分布、界面结构来满足高容量、大比功率及长循环寿命的要求。 相似文献
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利用低共熔混合物LiNO3-LiOH为锂盐,与高密度前驱体Ni0.8CO0.2(OH)2混合烧结制备出了高密度锂离子电池正极材料LiNi0.8Co0.2O2.探讨了合成温度、合成时间等因素对产品的影响.X射线衍射分析表明合成的LiNi0.8Co0.2O2具有规整的层状NaFeO2结构,充放电测试表明在3.0~4.3V的电压范围内,首次放电比容量可达168mAh/g,充放电效率为95%.结果表明采用该工艺可以制备出电化学性能良好的高密度LiNi0.8Co0.2O2正极材料. 相似文献
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《Advanced Powder Technology》2022,33(2):103415
In this study, the porous material zeolite with cage-like structure was modified to prepare silver-doped zeolite 4A (abbreviated as Ag@4A) using ion exchange method, with a silver loading of 34.2 wt% and a specific surface area of ??23.62 m2/g. The adsorption performance of Ag@4A for anionic iodine in LiCl-KCl molten salt system was investigated through static adsorption experiments. The modified adsorbents and experimental samples were analyzed by XRD, SEM, ICP-OES and other methods. At 550 °C, compared with the unmodified zeolite 4A, adsorption capacity of 34 mg/g of iodine, the maximum adsorption capacity of Ag@4A for iodine ions was up to 160 mg/g. When Cs+ existed in the system, the maximum adsorption capacity of Ag@4A for iodide ions was about 64 mg/g; when Cs+ and Sr2+ coexisted, the maximum adsorption capacity of Ag@4A for iodide ions decreased to 103 mg/g. Ag@4A also showed a certain adsorption capacity for Cs+ and Sr2+. These results indicated that the Ag@4A has potential application for the removal of iodide ions and other cations in chloride molten salt. 相似文献
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Hydrated amorphous FePO4 was synthesized by a sonochemical reaction method, in which a solution of (NH4)2HPO4 and FeSO4·7H2O was irradiated by an ultrasonic wave. From this material, two kinds of cathode materials were easily prepared: (1) an amorphous sample prepared by heating at 350 °C and (2) a crystalline sample prepared by heating at 700 °C. Both samples consisted of homogeneous sub-micron particles. The amorphous sample of FePO4 exhibited high discharge capacities with more than 100 mAh g−1 in the range of 3.9-2.0 V versus Li/Li+ at a current rate of 0.2 C. The sonochemical synthesis proposed herein has the following advantages: no use of oxidation agents for production of trivalent iron ions, reduction in reaction time, control of particle size, and enlargement in surface area for the preparation of the cathode material. 相似文献
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Widely used synthetic dyes are one of the main pollutants that contaminate water environments seriously. From the environmental perspective, efficient adsorption of these wastes such as Congo red (CR) is of great importance, and numbers of adsorbents including inorganic materials have been developed. Herein, a lanthanide tetraboride nanocrystal powder CeB4 with an average particle size of 50 nm synthesized for the first time via inorganic molten salt synthesis route using cerium fluoride (CeF3) and sodium borohydride (NaBH4) as the cerium and boron precursors in argon atmosphere exhibits good performance for the adsorption of CR. Essential effluence factors, such as initial pH value, contacting time, and initial concentration, were experimentally evaluated. The adsorption was pH dependent, and the kinetic data follow the pseudo–second–order kinetic model. It was also found that the equilibrium adsorption data could be represented by Langmuir and Freundlich isotherm models, with a maximum capacity of 491.8 mg/g. On the basis of the adsorption–desorption experiments, CeB4 exhibits good reusability. 相似文献
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Yingbin Lin Ying Lin Ting ZhouGuiying Zhao Yandan HuangYanmin Yang Zhigao Huang 《Materials Chemistry and Physics》2013
LiFePO4/Si composites are synthesized via a simple milling isopropanol mixtures process, and the effects of Si-modification on the electrochemical performances of LiFePO4 are investigated systematically by charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. In comparison with the pristine LiFePO4, LiFePO4/Si-nanoparticle shows better cyclability and higher rate capability, especially at elevated temperature. An analysis of the electrochemical measurements indicates that Si incorporation could significantly improve the electrochemical performance at high charge/discharge rate and elevated temperature. Among the investigated samples, (LiFePO4)98/(Si)2 sample shows the best electrochemical performance with 150 mAhg−1 at 0.5C at 60 °C. The enhancement could be mainly attributed to the lower charge-transfer resistance and higher lithium diffusion coefficients. In addition, the dangling bonds of Si and fluorosilica compounds are responsible for suppressing the dissolution of Fe2+ from olivine phase and preventing the rise of the surface resistance and charge transfer resistance. 相似文献
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本文以甘蔗渣作为生物质碳源制备Na2MnPO4F/C正极材料。通过球磨法及原位热解法制备Na2MnPO4F/C正极材料,利用拉曼光谱对正极材料制备条件进行表征分析,得出Na2MnPO4F/C最佳制备条件为碳源用量15%、煅烧温度600℃。利用XRD、SEM、EDS、电化学测量技术等手段对材料进行表征分析,结果表明,材料结晶性良好,碳材料很好地包覆在Na2MnPO4F聚氟阴离子材料表面,并且不影响材料结构。组装成纽扣电池,进行电化学性能测试。结果表明Na2MnPO4F/C材料电化学性能优于Na2MnPO4F材料,在0.1C下,Na2MnPO4F/C材料首圈放电比容量为8.71 m Ah/g,而Na2MnPO4F材料首圈放电比容量为1.94 m Ah/g,通过原位热解法进行碳包覆能有效的提高材料的电子电导性,增加容量。 相似文献