摘要
钠离子电池和锂离子电池具有近似的电荷存储原理，但因为钠资源更丰富、成本更低廉，所以是未来大规模储能领域最具潜力的器件选择。然而，缺乏合适的负极材料制约了钠离子电池的发展，碳材料仍然是最有潜力的选择之一。研究者们对于各类碳材料都开展了系统的研究，然而碳材料的储钠机理尚不明晰且电化学性能仍需要进一步的提高。针对上述问题，本文以碳材料的基本结构单元石墨烯为出发点，从表面改性和堆垛结构调控两个角度入手，分别设计并制备了硫功能化多孔石墨烯宏观体和生物质硬碳两种不同的碳材料，研究了其作为钠离子电池负极材料的性能，主要内容和结论如下：
马化腾背景
首先，我们对石墨烯宏观体进行表面功能化，引入了有电化学活性的含硫官能团，得到硫功能化多孔石墨烯宏观体（SPGM），在用作钠离子电池负极材料时，在0.1 A/g的电流密度下比容量达400 mAh/g左右，同时展现优异的倍率性能，5 A/g 的电流密度下比容量高达123 mAh/g，机理研究证明含硫官能团-C-S x-C-（x=1-2）是高容量的主要来源。同时我们系统探究了硫含量对石墨烯宏观体的结构和性能的影响，低硫含量时可逆容量较低，而高硫含量时容量衰减较快，优化的硫含量（16.8 wt%）则可以很好地平衡可逆容量和循环稳定性，实现了电化学性能的最优方案。win10背景
除表面化学外，硬碳材料中的石墨微晶的堆垛结构也会影响储钠行为和性能。因此，我们从调控微晶中石墨烯片层的堆垛结构入手，首次以废弃的生物质荔枝壳为前驱体，经过简单的高温碳化制备了荔枝壳
硬碳（LSC）。碳化温度对于荔枝壳硬碳的石墨烯堆垛结构以及储钠性能起到关键性作用。随着碳化温度从900 ℃到1400 ℃，比表面积减小，石墨烯片层堆垛的有序度提高，片层间距扩大，硬碳的储钠容量也随之逐渐提高，首次库伦效率总体呈现上升趋势。其中经历1400 ℃碳化的硬碳可逆比容量可高达334 mAh/g，首次库伦效率为72%。
此外，本文以产业化正极Na[Ni1/3Fe1/3Mn1/3]O2和荔枝壳硬碳（LSC）分别为正负极电极材料，组装了钠离子全电池，比容量可达57 mAh/g，能量密度为177 Wh/kg。关键词：钠离子电池；负极材料；硫功能化石墨烯；硬碳；全电池
Abstract
Sodium-ion batteries (SIBs) posss similar charge storage principle to lithium-ion batteries and are the most promising choice for large scale energy storage, becau of the abundant natural resources and lower cost of sodium. However, the lack of appropriate anode materials verely restricts the development of SIBs. Carbon materials are the most potential candidate. V arious kind of carbon materials have been widely investigated, but the sodium storage mechanism is still debatable and the electrochemical performance still need further improving. To address above-mentioned issues, solutions are propod from the perspective of graphene, which is the basic struct
ural unit of carbon materials. From both surface modification and stacking structure regulation approaches, two different kind of carbon materials, namely sulfur functionalized porous graphene monolith and biomass-derived hard carbon respectively, are designed and prepared as the anodes for SIBs. The main content and conclusion are as follows:
Firstly, we functionalized the graphene monolith and introduced electrochemical active sulfur-containing functional groups on the surface of graphene. to obtain sulfur functionalized porous graphene monolith (donated as SPGM). The prepared SPGM delivered a high capacity of ~400 mAh/g at the current density of 0.1 A/g. Besides, excellent rate capability were demonstrated as well, namely ahigh reversible capacity of 123 mAh/g can be achieved even at a current density of 5 A/g. It’s further unvealed that -C-S x-C- （x=1-2）sulfur-containing functional groups are the main contribution of high capacity of SPGM. We also investigated the the influences of sulfur contents on the micro-structure and electrochemical performance of SPGM. The as-prepared SPGM with a low sulfur content delivers lower initial reversible capacity while the SPGM with high sulfur content suffers a fast capacity fading. The SPGM with optimized sulfur contents (16.8 wt%) can obtain both high capacity and good cycling stability.
洋奶粉
In addition to the modification of surface chemistry, the regulation of stacking structure of graphene a
lso influenced the sodium storage behavior and electrochemical performance of carbon materials. Therefore, we aimed to regulate the stacking structure of graphene. The wasted biomass litchi shell was utilized as carbon precursor to prepare the litchi shell-derived hard carbon (denoted as LSC) through a simple high-temperature
springycarbonization process under inert atmosphere for the first time. It’s found that carbonization temperature was the key factor for the regulation of stacking structure of graphene and enhancing electrochemical performance. From 900 ℃ to 1400 ℃, along with the increa of temperature of carbonization, the obtained LSC witnesd a decrea in specific surface area and increasin the ordered stacking degree of graphene sheets and interlayer distance. Therefore, the sodium storage capability is incread and the initial coulombic efficiency is on the increasing trend as a whole. The sample prepared at 1400 ℃ exhibited a high capacity of 334 mAh/g and a high initial coulombic efficiency of 72 % under a current density of 20 mA/g
Furthermore, we asmbled full sodium-ion batteries with LSC-1400 as the anode and Na[Ni1/3Fe1/3Mn1/3]O2as the cathode, which delivered a high capacity of 57 mAh/gand energy density of 177 Wh/kg.
Key words: sodium-ion battery; anode material; sulfur-functionalized graphene;观察日记一百字
hard carbon; full battery
目录
第1章绪论 (1)
1.1 钠离子电池的兴起 (1)
1.2 钠离子电池简介 (2)
1.2.1 工作原理 (2)
1.2.2 正极材料 (3)
1.2.3 负极材料 (6)
1.2.4 电解液 (8)
1.3 碳基负极材料 (10)
1.3.1 石墨与类石墨层状碳材料 (10)
雅思高分范文
1.3.2 硬碳类材料 (12)
1.3.3 纳米碳材料 (14)
1.4 钠离子电池产业发展现状 (15)
1.5 课题研究内容 (17)
第2章实验方法 (18)
2.1 材料与试剂 (18)
2.2 实验设备 (18)
2.3 结构表征设备和型号 (19)
2.4 电化学分析方法 (20)
2.4.1 循环伏安法 (21)
2.4.2 恒流充放电法 (21)
2.4.3 电化学交流阻抗法 (21)
第3章硫功能化多孔石墨烯宏观体的制备和储钠性能研究 (22)
3.1 引言 (22)
3.2 材料的制备及表征 (23)
3.2.1 制备工艺 (23)
3.2.2 形貌与结构表征 (24)
3.3 储钠性能研究 (30)
3.3.1 钠离子半电池的组装和测试 (30)
3.3.2 电化学性能测试结果及分析 (31)体坛快讯
3.4 储钠反应机理探究 (34)
3.5 硫含量对结构及储钠性能的影响 (36)
3.5.1 形貌与结构表征 (37)
3.5.2 电化学性能测试与分析 (38)
3.6 本章小结 (39)
第4章荔枝壳硬碳的制备及储钠性能研究 (41)
4.1 引言 (41)
4.2 材料的制备及表征 (42)
4.3 电化学性能研究 (45)
4.4 储钠机理探究 (48)
4.5 本章小结 (50)
第5章钠离子全电池的组装和测试 (52)
5.1 引言 (52)
5.2 正极材料Na[Ni1/3Fe1/3Mn1/3]O2的结构和性能表征 (53)
5.3 全电池的组装和测试 (54)
5.3.1 不同正负极质量比的全电池 (54)
5.3.2 最优化正负极质量比的全电池的电化学测试 (56)
5.4 本章小结 (57)
食品安全监管第6章结论与展望 (58)
6.1 创新点 (58)
6.2 主要结论 (58)
6.3 今后工作展望 (59)
参考文献 (60)
致谢 (64)
声明 (65)
个人简历、在学期间发表的学术论文与研究成果 (66)
