共查询到20条相似文献,搜索用时 46 毫秒
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针对镍钴铝酸锂(NCA)三元正极材料普遍存在的循环寿命差、浆料容易凝胶等缺点进行了硼酸喷雾包覆的改性。采用X 射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)及电化学测试等方法对硼酸包覆改性前后的材料性能进行了对比表征和分析。结果表明:喷雾包覆后可以在NCA正极材料表面形成一层保护层,改性后的NCA三元正极材料循环寿命有明显提升,特别是高温(45 ℃)1C/1C倍率下循环50次容量保持率由改性前的88.0%提升至改性后的95.2%,提升近7%;硼酸包覆可以改善NCA表面特性,使正极浆料稳定性大大提高。改性后的NCA正极浆料可以稳定放置168 h(7 d),解决了NCA正极材料容易凝胶的问题。 相似文献
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为了比较不同合成方法对锰酸锂(Li4Mn5O12)锂离子筛的结构、饱和交换容量和分离因子的影响,采用低温固相反应法和溶胶-凝胶法合成了锰酸锂锂离子筛,并用X射线衍射(XRD)表征了所得材料的结构.结果表明,低温固相反应法和溶胶-凝胶法制备的锰酸锂及其离子筛均为尖晶石结构.低温固相反应法合成的锂离子筛,其锂离子饱和交换容量为16.06 mg/g(2.31 mmol/g)、分离因子αLiNa为23;溶胶-凝胶法合成的锰酸锂锂离子筛,其锂离子饱和交换容量为26.39 mg/g(3.80 mmol/g),分离因子αLiNa为216,优于低温固相反应法所得锂离子筛的性能. 相似文献
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This review is concerned with alternatives to metallic lithium for use in rechargeable lithium batteries. Emphasis is placed on the use of various materials and combinations of materials in different types of electrodes rather than on the properties of the materials themselves. The review includes carbon based electrodes, alloys, conducting polymers and transition metal compounds. Special consideration is given to electrodes and materials used in organic liquid and polymer electrolytes, whereas liquid cathode and molten salt systems are excluded. 相似文献
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Graphene nanosheets were synthesized in large quantities using a chemical approach. Field emission electron microscope observation revealed that loose graphene nanosheets agglomerated and crumpled naturally into shapes resembling flower-petals. High resolution transmission electron microscope analysis, Raman spectroscopy and ultraviolet-visible spectroscopy measurements confirmed the graphitic crystalline structure of the graphene nanosheets. The nanosheets exhibited an enhanced lithium storage capacity as anodes in lithium-ion cells and good cyclic performance. 相似文献
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Na2Li2Ti6O14电池具有较低的电位平台(1.3 V)以及经济成本低的特点,对便携式电子设备、能源汽车、生态环境等领域具有重大意义。由于钛酸锂钠电池固有离子电导率低的特点,因此提高钛酸锂钠电池锂离子扩散系数是目前研究中的主流方向,为此综述了钛酸锂钠的结构特点以及合成方法对钛酸锂钠材料粒径、形貌及电池电化学性能的影响;对比了不同掺杂离子和表面包覆改性对钛酸锂钠电池的放电比容量、循环性能及离子扩散系数的影响。掺入适量元素铌具有更高的锂离子扩散系数;包覆碳纳米管有更大的容量保持率,更有助于进一步提高钛酸锂钠电池电化学性能。 相似文献
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In order to reduce the loss of lithium in waste solutions of chemico-metallurgical lithium carbonate production, it is suggested to extract lithium from these solutions in the form of poorly soluble hydroxodialuminate under the action of sodium and potassium aluminates. Technological tests showed that the proposed method ensures almost complete isolation of lithium from waste solutions of lithium carbonate production. 相似文献
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Xin Shen Rui Zhang Shuhao Wang Xiang Chen Chuan Zhao Elena Kuzmina Elena Karaseva Vladimir Kolosnitsyn Qiang Zhang 《中国化学工程学报》2021,37(9):137-143
Lithium (Li) metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li den-drites in Li metal anodes remarkably hinders the practical applications of Li metal anodes.Herein,the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy.As revealed by the phase field simulations,the formation of aggregated Li dendrites under high current den-sity is attributed to the locally concentrated electric field rather than the depletion of Li ions.More specif-ically,the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities.Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites,and ultimately columnar Li morphology.The methodol-ogy and mechanistic understanding established herein give a significant step toward the practical appli-cations of Li metal anodes. 相似文献
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介绍了合成高纯无水的LiBF4和LiAsF6的新方法,并讨论了其合成条件,指出制备多孔状LiF和控制反应温度是合成的关键。 相似文献
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Atef Y. Shenouda 《Electrochimica acta》2006,51(26):5973-5981
New vanadate compounds having the molecular structure LixMg1−xV2−xMoxO6 (0 ≤ x ≤ 1) were studied. Six samples were prepared by sol-gel process from precursor using the following ratios of x = 0, 0.2, 0.4, 0.6, 0.8 and 1, respectively. These samples were labeled S1, S2, S3, S4, S5 and S6. The final process of firing occurred at 750 °C for 18 h in air. The prepared materials were characterized by XRD, SEM, IR, electron spin resonance (ESR) and magnetic measurements. The morphologies of S1, S2, S5 and S6 are prismatic as they have monoclinic crystal structures. S3 and S4 differ in the crystal morphology from the other previous samples due to their triclinic crystal lattice structure. IR spectra revealed that the bond lengths of the vanadyl groups νVO, νsy V-O and σV-O increase in the same direction from S1 to S6. The data of the ESR explain the existence of V4+ beside V5+ in S1, S4 and S6 and also presence of Mo5+ with Mo6+ in S4 and S6. S4 exhibited better magnetic susceptibility and saturated magnetization than the other samples. The first specific discharge capacities of the samples were performed. S4 showed the maximum specific capacity of 265 mAh g−1 in comparison with the other samples. Cyclic voltammogram of S4 exhibited the highest current intensity in comparison with the other samples. This sample showed two peaks at 0.53 and 1.3 V versus Li/Li+ characterizing double de-insertions of two lithium atoms from Li1.6Mg0.4V1.4Mo0.6O6−x and Li0.6Mg0.4V1.4Mo0.6O6, respectively. Also, two additional peaks were characterized for the oxidation of Mo5+ to Mo6+ and V4+ to V5+ at 3.5 and 4 V, respectively. 相似文献
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锂离子电池正极材料锰酸锂的改性研究 总被引:2,自引:1,他引:1
用氟化锂对预先合成的锰酸锂(LiMn2O4)进行氟化处理,研究了处理温度对材料电化学比容量与高温下循环稳定性的影响.结果表明,氟化锂/锰酸锂混合体系在500 ℃以上开始反应,所形成材料的特性发生了明显的变化;氟化锂处理可以改善锰酸锂材料的结晶度,热处理温度越高,处理后材料的结晶度越好;随着处理温度的升高,锰酸锂材料经历了从"烧结型"到"结晶型"的转变,700 ℃以上烧结的材料形成了八面体的晶体颗粒;初始比容量与循环性能也随着处理温度的不同而变化,600 ℃条件下处理的材料初始比容量最低,但循环性能最好. 相似文献