This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.

This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.

The thesis deals with the production and evaluation of porous carbon materials for energy storage technologies, namely super capacitors and lithium sulfur batteries. / Die Doktorarbeit befasst sich mit der Produktion und Evaluierung poröser Kohlenstoffmaterialien für die Anwendung in Energiespeichertechnologien, namentlich Superkondensatoren und Lithiumschwefelbatterien.

Nowadays, new approaches to fabricate high-performance electrode materials are of vital importance in the renewable energy field. Here, we present a facile synthesis procedure of 3D Ni(OH)2/graphene hybrids for supercapacitors via synchronous electrochemical-assisted exfoliation and assembly of graphene on 3D Ni(OH)2 networks. With the assistance of an electric field, the electrochemically exfoliated high-quality graphene can be readily, uniformly assembled on the surfaces of 3D Ni(OH)2. When serving as electrode materials for supercapacitors, the resulting 3D Ni(OH)2/graphene composites exhibited excellent specific capacitance (263 mF cm−2 at 2 mA cm−2), remarkable rate capability and super-long cycle life (retention of 94.1% even after 10 000 continuous charge–discharge cycles), which may be attributed to their highly porous, stable 3D architecture as well as uniform, firm anchoring of ultrathin graphene on their surfaces. Therefore, our approach provides a facile strategy for the large-scale synthesis of high-quality graphene based composites towards various applications.

Nitrogen-doped (N-doped) porous carbons have drawn increasing attention due to their high activity for electrochemical catalysis, and high capacity for lithium-ion (Li-ion) batteries and supercapacitors. So far, the controlled synthesis of N-enriched ordered mesoporous carbons (N-OMCs) for Li-ion batteries is rarely reported due to the lack of a reliable nitrogen-doping protocol that maintains the ordered mesoporous structure. In order to realize this, in this work, ordered mesoporous carbons with controllable N contents were successfully prepared by using melamine, F127 and phenolic resin as the N-source, template and carbon-source respectively via a solvent-free ball-milling method. The as-prepared N-OMCs which showed a high N content up to 31.7 wt% were used as anodes for Li-ion batteries. Remarkably, the N-OMCs with an N content of 24.4 wt% exhibit the highest reversible capacity (506 mA h g−1) even after 300 cycles at 300 mA g−1 and a capacity retention of 103.3%. N-OMCs were also used as electrode materials in supercapacitors and a capacity of 150 F g−1 at 0.2 A g−1 with stable cycling up to 2500 times at 1 A g−1 was achieved. These attractive results encourage the design and synthesis of high heteroatom content ordered porous carbons for applications in the field of energy storage and conversion.

Within the different available electrochemical energy storage systems, supercapacitors stand out due to their high power densities and ultra-long cycle life. Their key-components are the electrode materials where the charge accumulation takes place and therefore many different approaches for the synthesis of carbonaceous electrode structures with well-defined pore systems are available. This review focuses on different strategies for tailoring porous carbon materials from the micropore level, over mesopores to macropores and even external or inter-particular porosity. A wide range of materials such as activated carbons, templated carbons, carbide-derived carbons, carbon nanotubes, carbon aerogels, carbon onions, graphenes and carbon nanofibers are presented, always in relation to their pore structure and potential use in supercapacitor devices.

Monolithic integration of iontronic devices is a key challenge for future miniaturization and system integration. The G-Cap, a novel iontronic element, is a switchable supercapacitor with gating characteristics comparable to transistors in electronic circuits, but switching relies on ionic currents and ion electroadsorption. The first monolithic in-plane G-Cap integration through 3D-inkjet printing of nanoporous carbon precursors is reported. The printed G-Cap has a three-electrode architecture integrating a symmetric “working” supercapacitor (W-Cap) and a third “gate” electrode (G-electrode) that reversibly depletes/injects electrolyte ions into the system, effectively controlling the “working” capacitance. The symmetric W-Cap operates with a proton-conducting hydrogel electrolyte PVA/H₂SO₄ and shows a high capacitance (1.6 mF cm⁻²) that can be switched “on” and “off” by applying a DC bias potential (-1.0 V) at the G-electrode. This effectively suppresses AC electroadsorption in the nanoporous carbon electrodes of the W-Cap, resulting in a high capacitance drop from an “on” to an “off” state. The new monolithic structures achieve high rate performance, reversible on-off switching with an off-value reaching 0.5 %, which even surpasses recently reported values. Establishing technologies and device architectures for functional ionic electroadsorption devices is crucial for diverse fields ranging from microelectronics and iontronics to biointerfacing and neuromodulation.

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This paper reports a simple self-assembly strategy towards bowl-shaped carbon-containing hollow particles, as well as an unprecedented potential application for block copolymer vesicles in energy storage. Kippah vesicles (fully collapsed vesicles), formed by solution self-assembly of an amphiphilic polystyrene-block-poly(ethylene oxide) block copolymer, were employed as the template to guide the formation of bowl-shaped nitrogen-doped carbon hollow particles (BNCHPs). As electrode materials of supercapacitors, BNCHPs exhibit superior electrochemical performance. In particular, compared with their spherical counterpart, BNCHPs largely increase their volumetric packing density, leading to much higher volumetric capacitance or volume reduction of electrodes, which is desired for practical supercapacitor devices.