摘要
设计高体积能量密度的电极材料,是实现电化学器件致密储能的重要途径之一~([1,2])。但是,目前电极材料的高电化学活性并没有反应在器件上。这是因为从器件角度来讲,不仅需要设计高比容量的电极,还需要兼顾电极密度、电极厚度以及工作电压~([3])。由石墨烯组装体出发,我们提出了一种新颖的方法来制备石墨烯基厚密电极。通过引入氯化锌造孔剂以及毛细蒸发干燥的方式~([4]),石墨烯块体材料的比表面积能够在370m~2 g~(-1)~1000 m~2 g~(-1)范围内连续调节,同时还能保持较大的块体密度(1.6 g cm~(-3)~0.6 g cm~(-3))。该石墨烯块体可直接切割用于超级电容器电极材料。通过平衡电极的孔隙度和密度,该石墨烯电极在400μm的电极厚度下,仍可以在4 V离子液体体系下贡献出150 F cm~(-3)的体积比容量,相应器件的体积能量密度高达64.7 Wh L~(-1),是目前报道的超级电容器体积能量密度的最高值。这项工作提出了高体积能量密度储能器件的设计原则,从材料设计的角度解决了器件能量密度的问题,为电化学器件的致密储能提供了导向作用。
Compact energy storage with high volumetric performance is highly important. However, the state-of-art electrodes remain far from the requirements due to the lack of consideration from a device prospective, which not only demands a high gravimetric capacity, but also needs to take into account of operation voltage, material density and electrode thickness. By introducing zinc chloride as a sacrificing pore former, together with capillary drying, the specific surface area of graphene monolith can be tuned from 370 to 1000 m~2 g~(-1) while keeping a high density from 1.6 to 0.6 g cm~(-3). For supercapacitors, the directly sliced electrode up to 400 μm thickness delivers a capacitance of 150 F cm~(-3) in ionic liquid, converting to a record high volumetric energy density of 64.7 Wh L~(-1). This study presents a design principle of electrode from material design to device performance, which paves up a new way towards compact energy storage.
引文
[1]Zhang,C.;Lv,W.;Tao,Y.;Yang,Q.-H.Energy Environ.Sci.2015,8,1390.
[2]Li,H.;Tao,Y.;Zheng,X.;Yang,Q.-H.Nanoscale,2015,7,18459.
[3]Li,H.;Tao,Y.;Zheng,X.;Yang,Q.-H.Energy Environ.Sci.2016,accepted.
[4]Tao,Y.;Xie,X.;Lv,W.;Yang,Q.H.Sci.Rep.2013,3,2975.
