Graphene-based Li-ion hybrid supercapacitors with ultrahigh performance
graphene, hybrid supercapacitor, Li-ion battery, supercapacitor
There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors (EDLCs), leading to next generation-Ⅱ supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 (LTO) composite anode (G–LTO) and a three-dimensional porous graphene–sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries (energy source) and supercapacitors (power source). Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA·h·g–1 for pure LTO, the G–LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·h·g–1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0–2.5 V vs. Li/Li+; these are among the highest values for LTO-based nanocomposites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg–1 at a rate of 0.4 C (2.5 h) over a wide voltage range (0–3 V), and still retained an energy density of 32 Wh·kg–1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.
Tsinghua University Press
Kai Leng,Fan Zhang,Long Zhang,Tengfei Zhang,Yingpeng Wu,Yanhong Lu,Yi Huang,Yongsheng Chen, Graphene-based Li-ion hybrid supercapacitors with ultrahigh performance. NanoRes.2013, 6(7): 581–592