【摘要】：鋰離子電池因為環(huán)境污染和能源危機等問題越來越嚴重而在人們日常生活中扮演著越來越重要的角色。但是以磷酸鐵鋰等為正極、石墨為負極的傳統(tǒng)鋰離子電池因為能量密度和功率密度較低等因素逐漸無法滿足人們對下一代鋰離子電池的需求。因此,發(fā)展新型的鋰離子電池材料、對材料進行改性及構建新型全電池具有重要研究意義。本文的主要內容包括以下幾個方面：1、采用一種簡單的分步沉淀法分別制備了一維微納層狀結構富鋰Li0.2Ni0.13co0.13Mno.54O2正極材料,高鎳LiNi0.8Co0.15Al0.05O2正極材料和尖晶石型CoMn2O4負極材料。一維Li1.2Ni0.13Co0.13Mn0.54O2微米棒展現了出色的電化學性能。其在0.1 C下首次放電容量達到300 mAhg-1,庫倫效率為86%,在2C倍率下循環(huán)100次容量保持率為90%,在10C高倍率下放電仍有127.7 mAh.g-1的放電容量。LiNi0.8CO0.15Al0.05O2微米棒也展現了出色的電化學性能。這主要因為-維微納結構的電極材料能有效縮短離子擴散距離、提供合適的電極和電解液接觸面積并能夠有效緩解材料在鋰離子脫嵌過程中的應力。為了解決富鋰材料首次庫倫效率低的問題,我們將制備的Li1.2Nio.13Co0.13微米棒在偏釩酸銨的水溶液中浸漬烘干,之后進行煅燒,得到Li1.2Ni0.13Co0.13Mn0.54O2-V2O5復合材料,經過改性,Li1.2Ni0.13Co0.13Mn0.54O2正極材料首次庫倫效率從86%提高到111%,放電容量也有了很大程度的提高。富鋰材料首次庫倫效率低的問題得到了有效解決。這主要因為V205是一種電化學活性物質,能與負極的鋰生成LixVO3等具有電化學活性的電極材料。2、將制備的Li1.2Ni0.13Co0.13Mn0.54O2微米棒與生長在銅基底上的Fe3O4/Cu陣列薄膜直接組裝構建新型Fe3O4/Cu全電池。通過調節(jié)正負極容量比為1.1：1不經過對負極的預活化這樣不僅可以利用富鋰首次的不可逆容量來彌補負極首次形成SEI膜所需的鋰量,也省去了預鋰化的繁瑣步驟。Li1.2Ni0.13Co0.13Mn0.54O2||Fe3O4/Cu全電池在0.1 C倍率下能量密度為230 Wh kg-1,在0.5 C倍率下循環(huán)50次能量密度仍能達到196Wh kg-1。
[Abstract]:Lithium-ion batteries play a more and more important role in people's daily life because of the more and more serious problems such as environmental pollution and energy crisis. However, the traditional lithium-ion batteries with lithium iron phosphate as positive electrode and graphite as negative electrode are gradually unable to meet the needs of the next generation lithium-ion batteries because of their low energy density and power density. Therefore, it is of great significance to develop new lithium-ion battery materials, modify the materials and construct a new type of whole battery. The main contents of this paper include the following aspects: 1. One-dimensional micro-nano layered lithium-rich Li0.2Ni0.13co0.13Mno.54O2 cathode materials were prepared by a simple step-by-step precipitation method. High nickel LiNi0.8Co0.15Al0.05O2 cathode material and spinel CoMn2O4 negative electrode material. One-dimensional Li1.2Ni0.13Co0.13Mn0.54O2 micrometer rods show excellent electrochemical performance. The first discharge capacity at 0.1C is 86% at 300 mAhg-1, Coulomb efficiency, and the capacity retention rate for 100 cycles is 90% at 2C rate. There is still a discharge capacity of 127.7 mAh.g-1 at high rate of 10C. LiNi0.8CO0.15Al0.05O2 micrometer rods also show excellent electrochemical performance. This is mainly due to the fact that the electrode material with Vivian micro-nano structure can effectively shorten the ion diffusion distance, provide a suitable contact area between electrode and electrolyte, and can effectively alleviate the stress of the material in the process of lithium ion deintercalation. In order to solve the problem of low Coulomb efficiency of lithium-rich materials for the first time, the prepared Li1.2Nio.13Co0.13 micron rods were soaked and dried in ammonium metavanadate aqueous solution, and then calcined to obtain Li1.2Ni0.13Co0.13Mn0.54O2-V2O5 composites. After modification, the Coulomb efficiency of Li1.2Ni0.13Co0.13Mn0.54O2 cathode material increased from 86% to 111% for the first time, and the discharge capacity was also greatly improved. For the first time, the problem of low Coulomb efficiency of lithium-rich materials has been effectively solved. This is mainly because V205 is a kind of electrochemical active substance, which can form LixVO3 and other electrode materials with electrochemical activity with lithium of negative electrode. 2, The prepared Li1.2Ni0.13Co0.13Mn0.54O2 micron rod and Fe3O4/Cu array film grown on copper substrate were directly assembled to construct a new type of Fe3O4/Cu whole cell. By adjusting the positive and negative electrode capacity ratio to 1.1 鈮，

本文編號：2494773