Hollow nanostructures的合成困境
• The template-free or self-templating bottom-up approaches：hardly extended to HGN synthesis； • A template-involving top-down strategy：no catalytic capability to regularly manage the arrangement of carbon atoms； • Thus, controllable synthesis of HGNs with an engineered hollow cavity, predetermined layer number, small size, and highly crystalline fewlayer graphene shells is rarely achieved
Results and Discussion
The in situ catalytic self-limited assembly of HGNs
Morphology and structure of α-Ni(OH)2-DS
Morphology and structure of HGNs Electrochemical performance of HGN-S Morphology of cycled HGN-S electrodes
The in situ catalytic self-limited assembly of HGNs
Morphology and structure of α-Ni(OH)2-DS
Morphology and structure of HGNs
Morphology and structure of HGNs
Research background B
• 研究背景： 中空纳米结构对提升电池性能有巨大优势， 但传统方法难以制作 • 研究目的： 提升锂硫电池容量；提高电池稳定性 • 解决方案： 中空石墨烯纳米球壳结构，嵌入硫合成复 合材料，作为电池正极
Abstract
• Hollow nanostructures： 表面积大；活性部位充分暴露；物质输运的动力学性能优良； 表面通透性好 • A mesoscale approach to fabricate graphene shells: 催化剂作用下，在原位形成的纳米颗粒上实现纳米石墨烯的自 限性组装 • Use: 石墨烯纳米球壳作为基体与S复合，用作锂硫电池正极材料 • Properties: 初始放电容量：1520mAh/g(0.1C) 电流密度从0.1C提升至2.0C，70%容量保持 1000次循环，每次衰减0.06%
Research background A
• Li-S batteriy: high theoretical energy density of 2600 Wh/kg; • S: naturally abundant, economically effective, and environmentally friendly; • Graphene and other nanostructured carbon materials: excellent conductivity, high specific surface area, accommodate large volume expansion; • Issues: Li-S battery: poor cycling life and rate performance S: large volumetric expansion，poor conductivity Graphene: couldn’t integrate all the structural benefits. • The concept of HGNs might be a promising strategy, which yet calls for new synthetic methodology.
Electrochemical performance of HGN-S
Morphology of cycled HGN-S electrodes
Conclusions
• HGNs通过介尺度催化自限性组装法合成，具有非常小瓣状相形态； • 原位形成的Ni基纳米颗粒既作为硬膜板，又充当催化剂，催化3D纳米 结构的石墨烯在硬膜板上沉积；
• HGNs的粒径为10-30nm，SSA高达979平米每克，孔体积1.98立方米每 克，被用在高倍率Li-S电池中作为基体来容纳S；
• HGN-S正极材料有高的放电容量（1520、1058、737mAh/g分别对应0.1、 2.0、5.0C的电流密度） • 在1.0C的电流密度下，初始放电容量1098mAh/g，1000次循环之后放 电容量419mAh/g；衰减速率平均每圈0.06%，这显著的低于其他无硝 酸锂电解液的基于石墨烯的Li-S电池；
文献汇报
硬膜板上催化作用下的自限性组装： 用在锂硫电池中的中尺度石墨烯纳米壳
汇报人：XXX
目录
Source of the article Research background Abstract Introduction Results and Discussion Conclusions
Source of the article
Hollow nanostructures新的合成方案
• A mesoscale catalytic self-limited assembly of hollow graphene spheres was proposed. • Hard templates and working catalysts: in situ formed nickel-based NPs • Carbon source: dodecyl sulfate(DS) • 3D mesostructure: zero-dimensional (0D) HGNs construct two-dimensional (2D) nanosheets and then assemble into a threedimensional (3D) mesostructure
Introduction
Hollow nanostructures的优势
Hollow nanostructures的合成困境
Hollow nanostructures新的合成方案
Hollow nanostructures的优势
• Applications：
catalysis, adsorption, chemical sensors, drug/gene delivery, and energy storage/conversion systems
• Hollow nanocrystals：
mesoscale hollow structure, nanoscale quantum effects, and atomic-scale periodic arrangement • Hollow graphene nanoshells(HGNs)： favourable electrical conductivity, good surface functionality, mechanical/chemical stability, and biocompatibility