锂离子电池正极材料LiNi_0.5Mn_1.5O_4表面包覆CuO的研究

本文首先通过共沉淀法和固相球磨法制备了纳米级的LiNi0.5Mn1.5O4高电压正极材料,然后通过溶胶-凝胶法制备了表面包覆CuO的CuO-LiNi0.5Mn1.5O4复合材料.通过对CuO包覆量为1%,3%和5%的复合材料的电化学性能对比,发现当包覆量为1%时,材料的性能最佳.在1 C下,材料的放电比容量高达126.1 mA h g?1,循环100次后容量保持率在99.5%.CuO包覆在纳米LiNi0.5Mn1.5O4材料表面,阻止电解液与活性颗粒的直接接触,削弱了电解液与LiNi0.5Mn1.5O4的相互作用,进而在一定程度上减缓了电解液的分解;CuO的包覆同时还缓解了电解液中HF对材料的攻击,阻止了锰的溶解和由此带来的结构改变,进而提高了材料的循环稳定性.     

Electrochemical intercalation kinetics of lithium ions for spinel LiNi0.5Mn1.5O4 cathode material

The crystal structure and electrochemical intercalation kinetics of spinel LiNi_0.5Mn_1.5O₄ such as the resistance of a solid electrolyte interphase (SEI) film, charge transfer resistance (R _ct), surface layer capacitance, exchange current density (i ₀), and chemical diffusion coefficient are evaluated by Fourier transform infrared (FT-IR) and electrochemical impedance spectroscopy (EIS), respectively. FT-IR shows that LiNi_0.5Mn_1.5O₄ thus obtained has a cubic spinel structure, which can be indexed in a space group of Fd3m with a disordering distribution of Ni. EIS indicates that R _s is almost a constant at different states of charge. The thickness of SEI film increases with increasing of the cell voltage. R _ct values evidently decreases when lithium ions deintercalated from the cathode in the voltage range from OCV to 4.6 V, and R _ct value increases with increasing potential of deintercalation over 4.7 V. i ₀ varies between 0.2 and 1.6 mA cm^?2, and the solid phase diffusion coefficient of Li⁺ changed depending on the electrode potential in the range of 10^?11–10^?9 cm² s^?1.     

Preparation of LiNi0.5Mn1.5O4 cathode materials by using different-sized Mn3O4 nanocrystals as precursors

Journal of Solid State Electrochemistry - High-voltage LiNi0.5Mn1.5O4 with a spinel structure is considered as important cathode materials for high-energy density Li-ion batteries (LIBs). In this...     

High performance LiNi0.5Mn1.5O4 cathode materials synthesized by a combinational annealing method

High performance LiNi_0.5Mn_1.5O₄ was prepared by a combinational annealing method. All samples were characterized by X-ray diffraction, infrared, and cell measurements. With increasing the annealing time at 600 °C, LiNi_0.5Mn_1.5O₄ showed a decreased lattice parameter and an enhanced Ni-ordering. The electrochemical property of LiNi_0.5Mn_1.5O₄ was optimized by controlling the annealing time. It was found that after annealing at 600 °C for 8 h, LiNi_0.5Mn_1.5O₄ can discharge up to 138 mA h g⁻¹ with a superior cycling performance at the rate of 5/7 C. High-rate test indicated that LiNi_0.5Mn_1.5O₄ exhibited excellent electrochemical performance when charged and discharged at 1.2 C and 2.5 C, respectively. The findings reported in this work are expected to pave the way for the practical application of LiNi_0.5Mn_1.5O₄.     

Synthesis and electrochemical performance of LiNi0.6Co0.2Mn0.2O2 as a concentration-gradient cathode material for lithium batteries

A well-ordered and spherical LiNi0.6Co0.2Mn0.2O2 cathode material was successfully synthesized from Ni and Mn concentration-gradient precursors via co-precipitation. The crystal structure, morphology and electrochemical properties of LiNi0.6Co0.2Mn0.2O2 were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and charge-discharge tests. The material delivered an initial discharge capacity of 174.3 mAh/g at 180 mA/g （1 C rate） between 2.8 and 4.3 V and more than 93.1% of that was retained after 100 cycles. In addition, it also exhibited excellent rate capability, high cut-off voltage and temperature performance.     

Dual-salts of LiTFSI and LiODFB for high voltage cathode LiNi0.5Mn1.5O4

Journal of Solid State Electrochemistry - The LiNi0.5Mn1.5O4 has been investigated as promising because of its high operating voltage (4.7 V vs. Li+/Li) and decent specific capacity....     

正极材料LiNi0.5Co0.5O2的电化学性能研究

以聚丙烯酰胺(PAM)为分散剂用微波—固相复合加热技术合成了层状锂离子电池正极材料LiNi0.5Co0.5O2。通过扫描电子显微镜(SEM)和X—射线粉末衍射(XRD)分析技术对材料的微观形貌和相结构进行了表征。恒电流充放电循环测试表明:材料的放电比容量高达154mAh/g,且有良好的循环性能。重点利用循环扫描伏安、计时电量和电化学交流阻抗测试技术,对材料在循环前后的电化学性能变化规律进行了探讨。结果表明,经过循环后材料的导电能力以及锂离子扩散能力都有了很大的提高。另外,材料中的锂含量对材料的导电能力也有很大的影响。     

Hierarchical hollow microcuboid LiNi0.5Mn1.5O4 as cathode material with excellent rate and cycling performance for lithium-ion batteries

Journal of Solid State Electrochemistry - The rational design of the structure is the key to engineering spinel LiNi0.5Mn1.5O4 cathode material to enhance Li+/electron transport and relieve the...     

Improving Interfacial Electrochemistry of LiNi0.5Mn1.5O4 Cathode Coated by Mn3O4

In this work the surface of LiNi\begin{document}$_{0.5}$\end{document}Mn\begin{document}$_{1.5}$\end{document}O\begin{document}$_{4}$\end{document} (LMN) particles is modified by Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating through a simple wet grinding method, the electronic conductivity is significantly improved from 1.53\begin{document}$\times$\end{document}10\begin{document}$^{-7}$\end{document} S/cm to 3.15\begin{document}$\times$\end{document}10\begin{document}$^{-5}$\end{document} S/cm after 2.6 wt% Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating. The electrochemical test results indicate that Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating dramatically enhances both rate performance and cycling capability (at 55 ℃) of LNM. Among the samples, 2.6 wt% Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document}-coated LNM not only exhibits excellent rate capability (a large capacity of 108 mAh/g at 10 C rate) but also shows 78% capacity retention at 55 ℃ and 1 C rate after 100 cycles.     

Enhancements of rate capability and cyclic performance of spinel LiNi0.5Mn1.5O4 by trace Ru-doping

The rate capability and cyclic performance of the LiNi_0.5Mn_1.5O₄ under high current density have been significantly improved by doping a small amount of ruthenium (Ru). Specifically, Li_1.1Ni_0.35Ru_0.05Mn_1.5O₄ and LiNi_0.4Ru_0.05Mn_1.5O₄ synthesized by solid state reaction can respectively deliver a discharge capacity of 108 and 117 mAh g^?1 at 10 C rate between 3 and 5 V. At 10 C charge/discharge rate, Li_1.1Ni_0.35Ru_0.05Mn_1.5O₄ and LiNi_0.4Ru_0.05Mn_1.5O₄ can respectively maintain 91% and 84% of their initial capacity after 500 cycles, demonstrating that Ru-doping could be a way to enhance the electrochemical performance of spinel LiNi_0.5Mn_1.5O₄.     

Enhanced electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode via dual-functional lanthanide modification

Journal of Solid State Electrochemistry - This study investigates the use of lanthanide elements to modify a layered oxide cathode through solid-state calcination. Based on the findings, the...     

锂离子电池用高电位正极材料LiNi0.5Mn1.5O4

由于具有工作电压高、工作范围宽、比能量大、无污染、使用寿命长等优点,锂离子电池具有广阔的应用前景。 然而,目前商业化的锂离子电池仍无法满足电动汽车对电池低成本及高能量密度的要求。研发比能量更高、价格更低廉、寿命更长的锂离子电池成为电动汽车产业发展的关键。尖晶石结构的镍锰酸锂（LiNi_0.5Mn_1.5O₄）具有三维扩散通道,有利于锂离子的传输,且结构稳定;其理论放电比容量可达147 mAh ·g^-1。 更重要的是,其电压平台高达4.7 V,具有高的能量密度与功率密度,被认为是未来锂离子电池发展中最具前途与吸引力的正极材料之一。本文介绍了LiNi_0.5Mn_1.5O₄的结构、制备方法、掺杂与包覆改性研究及其应用前景,着重介绍了材料的改性方法并指出LiNi_0.5Mn_1.5O₄目前亟需解决的问题和研究重点。     

Electrochemical performance of nano-sized ZnO-coated LiNi0.5Mn1.5O4 spinel as 5 V materials at elevated temperatures

ZnO-coated LiNi_0.5Mn_1.5O₄ powders with excellent electrochemical cyclability and structural stability have been synthesized. The electrochemical performance and structural stability of ZnO-coated LiNi_0.5Mn_1.5O₄ electrodes in the 5 V region at elevated temperature has been studied as function of the level of ZnO coating. The 1.5 wt% ZnO-coated LiNi_0.5Mn_1.5O₄ electrode delivers an initial discharge capacity of 137 mAh g⁻¹ with excellent cyclability at elevated temperature even at 55 °C. The reason for the excellent cycling performance of ZnO-coated LiNi_0.5Mn_1.5O₄ electrode is largely attributed to ZnO playing an important role of HF getting in the electrolyte.     

Spinel LiNi0.5Mn1.5O4 and its derivatives as cathodes for high-voltage Li-ion batteries

The spinel material LiNi_0.5Mn_1.5O₄ displays a remarkable property of high charge/discharge voltage plateau at around 4.7 V. It is a promising cathode material for new-generation lithium-ion batteries with high voltage. Recently, a lot of researches related to this material have been carried out. In this review we present a summary of these researches, including the structure, the mechanism of high voltage, and the latest developments in improving its electrochemical properties like rate ability and cycle performance at elevated temperature, etc. Doping element and synthesizing nanoscale material are effective ways to improve its rate ability. The novel battery systems, like LiNi_0.5Mn_1.5O₄/Li₅Ti₄O₁₂ with good electrochemical properties, are also in progress.     

Co-precipitation synthesis of precursor with lactic acid acting as chelating agent and the electrochemical properties of LiNi0.5Co0.2Mn0.3O2 cathode materials for lithium-ion battery

Journal of Solid State Electrochemistry - Hydroxide precursor Ni0.5Co0.2Mn0.3(OH)2 was successfully prepared by co-precipitation using lactic acid as the environment-friendly chelating agent. And...     

Enhanced electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode via wet-chemical coating of MgO

Journal of Solid State Electrochemistry - LiNi0.8Co0.1Mn0.1O2 (NCM811) has a high potential for using as the cathode material for lithium–ion batteries (LIBs) for electric vehicles owing to...     

Synthesis and electrochemical properties of high-voltage LiNi0.5Mn1.5O4 electrode material for Li-ion batteries by the polymer-pyrolysis method

A submicron LiNi_0.5Mn_1.5O₄ cathode was synthesized via the pyrolysis of polyacrylate salts as precursor polymerized by reaction of the metal salts with acrylate acid. The structure and morphology of the resulting compound was characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results reveal that the prepared LiNi_0.5Mn_1.5O₄ cathode material has a pure cubic spinel structure and submicron-sized morphology even if calcined at 900 °C and quenched to room temperature. The LiNi_0.5Mn_1.5O₄ electrodes exhibited promising high-rate characteristics and delivered stable discharge capacity (90 mAh/g) with excellent retention capacity at the current density of 50 mA/g between 3.5 and 4.9 V. The capacity of the LiNi_0.5Mn_1.5O₄ electrodes remains stable even after 30 cycles at low or high current density. This polymer-pyrolysis method is simple and particularly suitable for preparation of the spinel LiNi_0.5Mn_1.5O₄ cathode material compared to the conventional synthesis techniques.