锂离子电池高比容量NCA正极材料研究
发布时间：2019-01-24 12:06
【摘要】：为了实现绿色能源持续稳定的供应,研究和开发能量存储器件(如锂离子电池)的速度需要进一步加快。层状结构的LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 (NCA)正极材料,因其高容量的优势,成为高能量密度锂离子电池中的正极材料之一。本论文针对NCA材料,采用优化碳酸盐共沉淀的合成方法,通过AlPO4包覆NCA来提升性能,并设计及合成了一种梯度材料,并对它的性能进行研究。主要内容包括:1、碳酸盐共沉淀法合成NCA材料以LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 (NCA)为例,优化了合成条件,采取的反应温度为60℃,pH值为8.10,进料速度为500mL h-1,以一定的速度进行搅拌约1h后取出沉淀,进行过滤,洗涤和干燥,即得到大小均匀的NCA前驱体球形颗粒。然后与氢氧化锂以1:1.05的比例进行研磨混匀,在空气中高温锻烧一定时间,得到具有较好的层状结构以及良好电化学性能的NCA材料。2、AlP0_4包覆NCA材料制备及性能研究利用湿化学法在NCA表面均匀包覆了一层AlP0_4,目的是防止NCA与电解液接触时发生的副反应。NCA@AlPO4材料在充放电过程中具有较高的容量,同时具有优异的循环性能。在3.0-4.3 V的电压区间,0.5 C的倍率下循环150圈后,AlPO4包覆NCA材料的容量保持率为86.9%,高于未包覆的NCA(66.8%)。此外,由于NCA表面包覆层的作用,材料的热稳定性也得到极大提升。结果表明,AlP0_4包覆的NCA材料可以作为锂离子电池中具有高安全性和高容量的正极材料之一。3、梯度结构锂离子电池正极材料的制备与性能研究通过碳酸盐共沉淀法合成了浓度梯度的球形颗粒材料,该材料组成从内层的LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 (NCA)逐渐渡至外层的LiNi1/3Co1/3Mn1/3O2(NCM)。0.5 C的倍率下循环200圈后仍有99.8%的容量保持率,表现出优异的循环性能。这得益于NCM浓度梯度保护层对于内层NCA的保护作用。此外,材料具有更高的热稳定性和空气稳定性,可以满足日益增长的对于高能量密度,长循环寿命和高储能稳定性锂离子电池的需求。
[Abstract]:In order to achieve a sustainable and stable supply of green energy, the research and development of energy storage devices (such as lithium ion batteries) need to be further accelerated. Layered LiNi_ (0. 8) Co_ (0. 15) Al_ (0. 05) O\ -2 (NCA) cathode materials have become one of the cathode materials in high energy density lithium ion batteries due to their high capacity. In this paper, a kind of gradient material was designed and synthesized by optimizing the synthesis method of carbonate coprecipitation and AlPO4 coating NCA to improve the properties of NCA materials, and its properties were studied. The main contents are as follows: 1. The synthesis conditions of NCA materials synthesized by carbonate coprecipitation were optimized with LiNi_ (0.8) Co_ (0.15) Al_ (0. 05) O _ 2 (NCA) as an example, and the reaction temperature was 60 鈩，
本文编号：2414460
[Abstract]:In order to achieve a sustainable and stable supply of green energy, the research and development of energy storage devices (such as lithium ion batteries) need to be further accelerated. Layered LiNi_ (0. 8) Co_ (0. 15) Al_ (0. 05) O\ -2 (NCA) cathode materials have become one of the cathode materials in high energy density lithium ion batteries due to their high capacity. In this paper, a kind of gradient material was designed and synthesized by optimizing the synthesis method of carbonate coprecipitation and AlPO4 coating NCA to improve the properties of NCA materials, and its properties were studied. The main contents are as follows: 1. The synthesis conditions of NCA materials synthesized by carbonate coprecipitation were optimized with LiNi_ (0.8) Co_ (0.15) Al_ (0. 05) O _ 2 (NCA) as an example, and the reaction temperature was 60 鈩，
本文编号：2414460
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