锰系空心球形正极材料的制备及其电化学性能研究
发布时间：2018-07-14 09:13
【摘要】：锂离子电池如今被认为是未来混合电动和全电动汽车以及抑制温室效应的技术层面的选择。尖晶石锰酸锂作为一种正极材料,因其成本低、毒性小和相对较高的能量密度等优势而受到广泛的关注。然而,尖晶石结构的锰酸锂材料仍然存在其本身固有的Jahn-Teller效应和锰离子溶解等问题,高温下其容量衰减较为严重。为了改进锰酸锂正极材料的能量密度,通过制备镍锰酸锂的二元复合物材料,可以提高其充放电电压,也是改进其性能的一种方法。对于电极材料而言,形貌可控,大小均一的材料能够防止局部极化,增加锂离子的扩散作用。因而,我们首先通过沉淀法研究空心球形锰酸锂材料的制备及电化学性能;进而通过原位掺杂镍离子进入锰酸锂的晶格中,研究LiNi_(0.33)Mn_(1.67)O_4空心微球材料晶体结构、离子扩散、电化学性能的影响;在此基础上制备了高电压LiNi_(0.5)Mn_(1.5)O_4空心微球正极材料,对其进行了电化学性能研究。主要的研究工作如下:1.通过碳酸盐沉淀和固相烧结法,制备了空心球形结构的尖晶石锰酸锂正极材料。SEM结果显示该空心球粒径在3.0-4.0μm之间,具有多孔结构,其表面较为光滑。锂锰配比为0.53得到的样品具有优越的电化学性能,在首次充放电循环中,0.2 C下首次放电比容量为134.58 mAh g~(-1),首次充放电库伦效率达96.6%,在0.2 C下100次循环后容量保持率达95.1%,具有较好的循环稳定性。2.通过碳酸盐共沉淀法将镍离子原位掺杂制备Ni_(0.17)Mn_(0.83)CO_3空心球,固相烧结后制备了空心球形结构的尖晶石LiNi_(0.33)Mn_(1.67)O_4材料,使少量的镍离子取代锰酸锂结构中部分的Mn3+,利用镍离子的静电作用稳定锰酸锂的晶体结构,进而改善其循环稳定性。SEM结果显示该空心球粒径在2.0-4.0μm之间,反应条件研究结果表明在55℃进行共沉淀反应制备的产品形貌更为均一。该材料在0.5 C下的首次放电比容量为134.49 mAh g~(-1),在1.0 C下200次循环后容量保持率可达97.2%,在5.0 C倍率下放电比容量达124.11 mAh g~(-1),200次循环后的容量衰减在6.4%以内,具有较好的循环稳定性。与沉淀法制备的锰酸锂相比,该材料表现出更好的倍率性能。3.第二部分的研究发现,LiNi_(0.33)Mn_(1.67)O_4材料是锰酸锂和高电压LiNi_(0.5)Mn_(1.5)O_4的微晶混合形成的空心球结构。进一步在LiNi_(0.33)Mn_(1.67)O_4增加镍离子的含量,制备了纯相的LiNi_(0.5)Mn_(1.5)O_4空心微球。SEM结果显示该空心球粒径在3.5-4.5μm之间,具有多孔结构。EDS结果显示镍离子和锰离子在材料中分布很均匀。所得材料在0.5 C下首次放电比容量为135.21 mAh g~(-1),300次循环后容量保持率达92.0%,具有较高的比容量和较好的循环性能。其在2.0 C下放电比容量达124.47 mAh g~(-1),200次循环后的容量衰减在1.5%以内,说明其具有很优异的倍率性能。
[Abstract]:Lithium-ion batteries are now seen as the future technical options for hybrid electric and all-electric vehicles and for suppressing Greenhouse Effect. As a kind of cathode material, spinel lithium permanganate has attracted wide attention because of its advantages of low cost, low toxicity and relatively high energy density. However, the spinel LiMnO _ 4 material still has its inherent Jahn-Teller effect and manganese ion dissolution problems, and its capacity attenuation is serious at high temperature. In order to improve the energy density of lithium permanganate cathode material, the charge and discharge voltage of lithium nickel manganese oxide binary composite material can be increased by preparing it, and it is also a method to improve its performance. For electrode materials, the materials with controllable morphology and uniform size can prevent local polarization and increase the diffusion of lithium ions. Therefore, the preparation and electrochemical properties of hollow spherical lithium manganese oxide materials were studied by precipitation method, and then the crystal structure and ion diffusion of LiNi0.33 Mn1.67 O4 hollow microspheres were studied by in-situ doping of nickel ions into the lattice of lithium manganese oxide. The electrochemical properties of high voltage LiNi0.5 Mn1.5 O4 hollow microspheres cathode materials were prepared, and the electrochemical properties of the hollow microspheres were studied. The electrochemical properties of Lini _ (0.5) mn _ (1.5) O _ 4 hollow microspheres were investigated. The main research work is as follows: 1: 1. The hollow spherical spinel lithium manganese oxide cathode material was prepared by carbonate precipitation and solid phase sintering. The SEM results show that the hollow sphere has a porous structure and a smooth surface with a particle size ranging from 3.0 渭 m to 4.0 渭 m. The sample with Li / mn ratio of 0.53 has excellent electrochemical performance. In the first charge / discharge cycle, the first discharge specific capacity is 134.58 mAh g ~ (-1), the first charge / discharge Coulomb efficiency is 96. 6, and the capacity retention rate is 95. 1 after 100 cycles at 0. 2 C. it has good cycle stability. Ni _ (0.17) mn _ (0.83) CO _ 3 hollow spheres were prepared by in-situ doping of nickel ions by carbonate coprecipitation method. After solid phase sintering, spinel LiNi0.33 Mn1.67 O4 with hollow spherical structure was prepared. The crystal structure of lithium permanganate was stabilized by the electrostatic action of nickel ion, and the cyclic stability was improved. SEM results showed that the diameter of the hollow sphere was between 2.0 渭 m and 4.0 渭 m. The results of reaction conditions show that the morphology of the products prepared by coprecipitation at 55 鈩，
本文编号：2121177
[Abstract]:Lithium-ion batteries are now seen as the future technical options for hybrid electric and all-electric vehicles and for suppressing Greenhouse Effect. As a kind of cathode material, spinel lithium permanganate has attracted wide attention because of its advantages of low cost, low toxicity and relatively high energy density. However, the spinel LiMnO _ 4 material still has its inherent Jahn-Teller effect and manganese ion dissolution problems, and its capacity attenuation is serious at high temperature. In order to improve the energy density of lithium permanganate cathode material, the charge and discharge voltage of lithium nickel manganese oxide binary composite material can be increased by preparing it, and it is also a method to improve its performance. For electrode materials, the materials with controllable morphology and uniform size can prevent local polarization and increase the diffusion of lithium ions. Therefore, the preparation and electrochemical properties of hollow spherical lithium manganese oxide materials were studied by precipitation method, and then the crystal structure and ion diffusion of LiNi0.33 Mn1.67 O4 hollow microspheres were studied by in-situ doping of nickel ions into the lattice of lithium manganese oxide. The electrochemical properties of high voltage LiNi0.5 Mn1.5 O4 hollow microspheres cathode materials were prepared, and the electrochemical properties of the hollow microspheres were studied. The electrochemical properties of Lini _ (0.5) mn _ (1.5) O _ 4 hollow microspheres were investigated. The main research work is as follows: 1: 1. The hollow spherical spinel lithium manganese oxide cathode material was prepared by carbonate precipitation and solid phase sintering. The SEM results show that the hollow sphere has a porous structure and a smooth surface with a particle size ranging from 3.0 渭 m to 4.0 渭 m. The sample with Li / mn ratio of 0.53 has excellent electrochemical performance. In the first charge / discharge cycle, the first discharge specific capacity is 134.58 mAh g ~ (-1), the first charge / discharge Coulomb efficiency is 96. 6, and the capacity retention rate is 95. 1 after 100 cycles at 0. 2 C. it has good cycle stability. Ni _ (0.17) mn _ (0.83) CO _ 3 hollow spheres were prepared by in-situ doping of nickel ions by carbonate coprecipitation method. After solid phase sintering, spinel LiNi0.33 Mn1.67 O4 with hollow spherical structure was prepared. The crystal structure of lithium permanganate was stabilized by the electrostatic action of nickel ion, and the cyclic stability was improved. SEM results showed that the diameter of the hollow sphere was between 2.0 渭 m and 4.0 渭 m. The results of reaction conditions show that the morphology of the products prepared by coprecipitation at 55 鈩，
本文编号：2121177
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