With the dramatic developments of portable and wearable electronics, future energy storage devices become not only thin, light, and cheap, and but also ultraflexible. All-solid-state supercapacitors (ASSSs) with robust mechanical flexibility and safety are considered as one competitive alternative to high power sources for full integration into the manufacturing process of electronics.Herein, we demonstrate the first fabrication of stacked-layer heterostructure films (denoted as TP/EG) from thiophene (TP) nanosheets and electrochemically exfoliated graphene (EG) for high-rate and flexible ASSSs (TP/EG-ASSSs) and micro-supercapacitors (TP/EG-MSCs) with superior rate capability and enhanced volumetric capacitance. The heterostructure films with a thickness of ~105 nm are produced by alternating deposition of electrochemically EG nanosheets (≤3 layers) and redox-active conducting TP nanosheets (thickness of 3.5 nm) in sequence, and exhibit large-area uniformity. Notably, the produced films were directly transferred on a polyethylene terephthalate (PET) substrate and served as binder- and additive-free electrodes for flexible supercapacitors. Remarkably, the resulting TP/EG-ASSSs exhibited a pronounced pseudocapacitance contribution with strong redox peaks, and delivered an areal capacitance of ~3.9 mF cm-2 and a volumetric capacitance of ~375 F cm-3, energy density of 13 mWh cm-3 and power density of 776 W cm-3. Meanwhile, the TP/EG-MSCs can be operated at high rate of up to 1000 V s-1, offering ultrahigh rate capability, e.g., with a landmark areal capacitance of 1.30 mF cm-2 and volumetric capacitance of 123 F cm-3 at 100 V s-1, as well as unprecedented flexibility under different bending states. We believe that this strategy of assembling stacked-layer heterostructure films will open up novel possibility for realizing 2D graphene and analogous redox nanosheets for new-concept thin-film energy storage devices.
See the article: Z.-S. Wu,* Y.J. Zheng, S. H. Zheng, S. Wang, C. L. Sun, K. Parvez, T. Ikeda, X. H. Bao, K. Müllen,* X. L. Feng,* Stacked-Layer Heterostructure Films of 2D Thiophene Nanosheets and Graphene for High-Rate All-Solid-State Pseudocapacitors with Enhanced Volumetric Capacitance. Advanced Materials, 2016, online, DOI: 10.1002/adma.201602960.