Porous 3D Few-Layer Graphene-like Carbon for Ultrahigh-Power Supercapacitors with Well-Defined Structure-Performance Relationship
Porous 3D Few-Layer Graphene-like Carbon for Ultrahigh-Power Supercapacitors with Well-Defined Structure-Performance Relationship
复制标题
用于超高功率超级电容器的多孔 3D 少层类石墨烯碳，具有明确的结构 - 性能关系
DOI：
10.1002/adma.201604569
复制
发表时间：
2017
影响因子：
29.4
通讯作者：
Z. Hu
中科院分区：
文献类型：
--
作者：
J. Zhao;Y. F. Jiang;H. Fan;M. Liu;O. Zhuo;X. Z. Wang;Q. Wu;L. J. Yang;Y. W. Ma;Z. Hu
DOI：10.1002/ADMA。201604569保持甚至增强，随着润湿性的增加，超容性能将有很大的提升空间。众所周知，生长在金属模板上的石墨烯通常比生长在氧化物模板上的石墨烯具有更高的结晶度和更好的导电性。[6，7]基于这些考虑，我们发展了一种类似于原位氧化镁模板法的原位多孔铜模板法来制备三维多孔碳纳米材料。制备了一种独特的三维少层类石墨烯碳材料(3DG)，其特征是具有相互连通的微细孔结构、大比表面积(>；1500m2 g−1)、高电导率(>；800 S m−1)以及在水溶液或离子液体电解质中的高润湿性。结果表明，3DG在两种电解液中均表现出较高的超容性能。特别是，基于1000℃下制备的3DG的EDLC在水溶液和离子液体电解质中分别具有1066.2和740.8 kW kg−1的超高功率密度，具有极高的能量密度、倍率能力和循环稳定性。通过详细考察等效串联电阻(RESR)随电流密度的变化行为，结合经典的电化学阻抗谱，发现其优异的性能与其独特的结构密切相关。在800℃、900℃和1000℃下制备的3DG分别表示为3DG800、3DG900和3DG1000。图1显示了3DG1000的典型形态和结构特征。3DG1000基本上保持了从碱性碳酸铜前驱体继承而来的3D多孔铜模板的轮廓，并表现出核壳结构，壳和芯中都有大量大小不一的开孔。不同放大率的扫描电子显微镜(SEM)图像显示，中孔和大孔的多孔形态呈现出不规则的自相似分形，[8]并且壳比芯更致密(图1a-f和图S1(辅助信息))。透射电子显微镜(TEM)观察进一步表明，分级孔由厚度为1到3层的相互连接的皱折石墨化层组成(图1g，h)。3DG800和3DG900具有相似的功能(图S2，支持信息)。氮气吸附等温线中p/P0<；0.01处的陡峭吸收表明存在丰富的微孔。在0.42<；p/p0<；1处的新月形磁滞回线在高p/p0处没有表现出极限吸附，并且在对应于中孔和大孔的吸附区域之间没有明确的边界(图1I和图S3(辅助信息))。这是一个典型的H3型回路，证实了3DG是一个松散的网络和共存的微中孔。[9]这个等温线与碳基纳米容器的等温线有所不同。与电池相比，双电层电容器(EDLC)，也被称为超级电容器，由于其能够提供高功率密度和长时间循环稳定性而备受关注。[1]原则上，理想的EDLC电极材料应该同时满足以下要求：(I)高比表面积(SSA)以确保电荷存储空间，(Ii)均匀的孔分布以提高比电容和倍率能力，(Iii)高导电性以确保高倍率容量和功率密度，以及(Iv)良好的润湿性以促进离子扩散并增加离子可及表面积。[1，2]sp2碳材料因其良好的导电性、丰富的…而成为最常用的电极。
DOI: 10.1002/adma. 201604569 maintained or even enhanced with increasing wettability, there will be a big space for further improvement of supercapacitive performance. As known, graphene grown on a metallic template usually has higher crystallinity and better conductivity than that grown on an oxide template.[6, 7] Based on these considerations, herein we have developed an in situ porous Cu template method to prepare 3D hierarchical porous carbon nanomaterials in analogy to the in situ MgO template method. The unique 3D few-layer graphene-like carbon (3DG) is obtained which is characterized by the open porous architecture with interconnected micro-meso-macropores, large SSA (> 1500 m2 g− 1), high conductivity (> 800 S m− 1), and high wettability either in aqueous or in ionic liquid electrolytes. As a result, 3DG presents the high supercapacitive performances in both the electrolytes. Especially, EDLCs based on the 3DG prepared at 1000 C deliver ultrahigh maximum power densities of 1066.2 and 740.8 kW kg− 1 in aqueous and ionic liquid electrolytes, respectively, with a toplevel energy density, rate capability, and cycling stability. The excellent performance is well-associated with the unique structure by detailed examination on the changing behavior of equivalent series resistance (RESR) with current density combined with the classical electrochemical impedance spectroscopy. The 3DG prepared at 800, 900, and 1000 C are denoted as 3DG800, 3DG900, and 3DG1000, respectively. Figure 1 shows the typical morphological and structural characterizations of 3DG1000. Basically, 3DG1000 maintains the profile of the 3D porous Cu template inherited from the basic copper carbonate precursor, and demonstrates a core–shell structure with abundant open pores of different sizes in either the shell or the core. The porous morphology for meso-and macropores exhibits a self-similarity of irregular fractal as shown in the scanning electron microscopy (SEM) images with different magnifications,[8] and the shell is denser than the core (Figure 1a–f and Figure S1 (Supporting Information)). Transmission electron microscopy (TEM) observations further reveal that the hierarchical pores are composed of the interconnected crumpled sheets of one to three graphitized layers in thickness (Figure 1g, h). 3DG800 and 3DG900 exhibit similar features (Figure S2, Supporting Information). The steep uptake at p/p0< 0.01 in the N2 sorption isotherm indicates the existence of abundant micropores. The crescent-like hysteresis loop at 0.42< p/p0< 1 exhibits no limiting adsorption at high p/p0 and no clear boundary between the sorption regions corresponding to meso-and macropores (Figure 1i and Figure S3 (Supporting Information)). This is a typical type H3 loop, confirming a loose network and coexisting micro-meso-macropores for the 3DG.[9] This isotherm is somewhat different from that of the carbon-based nanocagesElectrical double layer capacitors (EDLCs), also called supercapacitors, have attracted much attention due to their capability of delivering high power density and long cycling stability as compared to batteries.[1] In principle, an ideal EDLC electrode material should simultaneously meet the requirements of:(i) a high specific surface area (SSA) to ensure the space for charge storage,(ii) well-balanced pore distribution to improve both specific capacitance and rate capability,(iii) high conductivity to ensure high rate capability and power density, and (iv) good wettability to facilitate ion diffusion and increase the ion-accessible surface area.[1, 2] sp2 carbon materials are the most commonly used electrodes due to their good conductivities, abundant …