锂离子电池负极材料硅酸锰的制备及其电化学性能研究

发布时间：2018-07-08 15:20

  本文选题：硅酸锰 + 碳包覆　； 参考：《山东大学》2017年硕士论文

【摘要】：作为一种新型绿色能源,锂离子二次电池受到了广泛的关注和研究,并逐渐应用于混合动力汽车等大型设备中。负极材料的选择会造成锂离子电池电化学性能的优劣差别。目前工业上碳材料应用比较广泛,但其容量较低,与现阶段人们对高能量密度能源的要求还有一定的差距,因此当下研究的方向为探求更高容量、更低成本的新型材料。本文运用简单的合成方法制备了硅酸锰负极材料,研究了其电化学性能。主要研究内容为:(1)利用Na_2SiO_3·9H_2O和MnCl_2·4H_2O的简单反应合成了硅酸锰。经过碳包覆的硅酸锰材料用作锂离子电池负极材料展现出优良的倍率性能及高倍率循环稳定性。在100、200、400、800和1600 mA/g电流密度下其比容量分别为323、293、261、227和176mAh/g,远高于商用石墨化材料。而其在500mA/g的电流密度下循环400次后,比容量仍能达到343 mAh/g,也比常用钛酸锂负极材料性能优良。结合电化学测试结果进行分析发现,在硅酸锰纳米颗粒周围均匀包裹的碳层提高了材料的导电性,且固态电解质硅酸锂的形成也有利于电化学性能的提升。碳包覆硅酸锰能够满足快速充放电锂离子电池的要求。(2)通过水煮处理Na_2SiO_3·9H_2O和MnCl_2·4H_2O的水溶液成功合成了非晶硅酸锰。以葡萄糖为碳源进行碳包覆后,即使在700 ℃下硅酸锰依旧能保持非晶态。将经过碳包覆的非晶硅酸锰材料用于锂离子电池负极材料并进行电化学性能测试,结果表明水煮4小时并在600 ℃碳包覆后获得的非晶硅酸锰材料具备最佳的循环性能,在500 mA/g电流密度下循环400次后,比容量仍能维持在421 mAh/g。这种非晶硅酸锰具有多孔结构及较大的比表面积,有利于锂离子的传输,并且在硅酸锰颗粒表面包覆的均匀碳层作为导电性材料也有助于其电子电导率的提升。
[Abstract]:As a new kind of green energy, lithium ion secondary battery has been widely paid attention to and studied, and has been gradually used in hybrid electric vehicles and other large equipment. The selection of anode materials will lead to the difference of electrochemical performance of lithium ion battery. At present, carbon materials are widely used in industry, but their capacity is relatively low, which is still far from the requirement of high energy density energy. Therefore, the current research direction is to explore new materials with higher capacity and lower cost. In this paper, manganese silicate anode materials were prepared by a simple synthesis method and their electrochemical properties were studied. The main research contents are as follows: (1) Manganese silicate was synthesized by the simple reaction of NaSZ _ 2SiO _ 3H _ 2O and MnCl _ 2H _ 2O. The carbon-coated manganese silicate used as anode material for lithium ion batteries shows excellent performance and high rate cycling stability. The specific capacity of 100200400800 and 1600 mA/g current density is 323293261227 and 176mAh/ g, respectively, which is much higher than that of commercial graphitization materials. After 400 cycles at the current density of 500mA/g, the specific capacity is 343mAh / g, which is better than that of lithium titanate anode material. The results of electrochemical measurement show that the carbon layer encapsulated uniformly around the manganese silicate nanoparticles improves the electrical conductivity of the material and the formation of lithium silicate as solid electrolyte is beneficial to the improvement of electrochemical performance. The carbon-coated manganese silicate can meet the requirements of rapid charge and discharge lithium-ion batteries. (2) Manganese silicate has been successfully synthesized by boiling Na2SiO3 9H 2O and MnCl 24 H 2O aqueous solutions. After carbon coating with glucose as carbon source, manganese silicate can remain amorphous even at 700 鈩，

本文编号：2107855