Highly Stable Supercapacitors with Conducting Polymer Core‐Shell Electrodes for Energy Storage Applications

Polyacrylonitrile (PAN)-based carbon precursor is a well-established and researched material for electrodes in energy storage applications due to its good physical properties and excellent electrochemical performance. However, in the fight of preserving the environment and pioneering renewable energy sources, environmentally sustainable carbon precursors with superior electrochemical performance are needed. Therefore, bio-based materials are excellent candidates to replace PAN as a carbon precursor. Depending on the design requirement (e.g. carbon morphology, doping level, specific surface area, pore size and volume, and electrochemical performance), the appropriate selection of carbon precursors can be made from a variety of biomass and biowaste materials. This review provides a summary and discussion on the preparation and characterization of the emerging and recent bio-based carbon precursors that can be used as electrodes in energy storage applications. The review is outlined based on the morphology of nanostructures and the precursor’s type. Furthermore, the review discusses and summarizes the excellent electrochemical performance of these recent carbon precursors in storage energy applications. Finally, a summary and outlook are also given. All this together portrays the promising role of bio-based carbon electrodes in energy storage applications.Graphic abstract

Aqueous rechargeable zinc-ion batteries (ARZIBs) are promising energy storage systems owing to their ecofriendliness, safety, and cost-efficiency. However, the sluggish Zn2+ diffusion kinetics originated from its inherent large atomic mass and high polarization remains an ongoing challenge. To this end, electrodes with 3D architectures and high porosity are highly desired. This work reports a rational design and fabrication of hierarchical core-shell structured cathodes (3D@V2 O5 ) for ARZIBs by integrating fused deposition modeling (FDM) 3D-printing with atomic layer deposition (ALD). The 3D-printed porous carbon network provides an entangled electron conductive core and interconnected ion diffusion channels, whereas ALD-coated V2 O5 serves as an active shell without sacrificing the porosity for facilitated Zn2+ diffusion. This endows the 3D@V2 O5 cathode with high specific capacity (425 mAh g-1 at 0.3 A g-1 ), competitive energy and power densities (316 Wh Kg-1 at 213 W kg-1 and 163 Wh Kg-1 at 3400 W kg-1 ), and good rate performance (221 mAh g-1 at 4.8 A g-1 ). The developed 3D@V2 O5 cathode provides a promising model for customized and scalable battery electrode engineering technology. As the ALD-coated layer determines the functional properties, the proposed strategy shows a promising prospect of FDM 3D printing using 1D carbon materials for future energy storage.

Optimising the fabrication of 3D binder-free graphene electrode for electrochemical energy storage application

Ternary nitrogen-doped graphene/nickel ferrite/polyaniline nanocomposites for high-performance supercapacitors

In the development of the next-generation safe solid-state supercapacitors with high energy density, durability, and flexibility, the synthesis of high ion conducting solid-state polymer electrolyte (SSPE) with electrochemical and mechanical stabilities is a great challenge. This study shows the promising potential of epoxy-based SSPEs containing oligoether, ionic liquid, and Li salt, where a microscopic fast ion-diffusing channel is bicontinuously interlaced with the macroscopic mechanical supporting cross-linked matrix via polymerization-induced microphase separation. Their ionic conductivities, mechanical, and dielectric properties are finely tuned through varying the Li salt concentration, thermodynamically leading to a change of the relative interactions of the two conducting and insulating phases, thereby creating variant morphologies (such as microscale, nanoscale, or less phase separation). The optimized SSPE, exhibiting an ionic conductivity of ∼10–3 S/cm and elongation at break of 153% at 25 °C, is assembled with activated carbon electrodes, allowing us to fabricate a flexible all-solid-state supercapacitor. The device shows a broad potential window (3 V), high specific capacitance (178 F/g at 0.1 A/g), large energy and power density (56 Wh/kg at 99 W/kg and 3.5 kW/kg at 13 Wh/kg), and remarkable electrochemical and mechanical stabilities under mechanical deformation (80% capacitance retention under rolling condition for 2000 cycles).

Performance of sunflower petal shaped CuCo2S4 wrapping on GO asymmetric capacitor for energy storage applications

Boosting the electrochemical performance and reliability of conducting polymer microelectrode via intermediate graphene for on-chip asymmetric micro-supercapacitor

SECONDARY BATTERIES – ZINC SYSTEMS | Zinc–Silver

ZnO doped SnO2 nano flower decorated on graphene oxide/polypyrrole nanotubes for symmetric supercapacitor applications

Nitrogen-doped reduced graphene oxide/MoS2 ‘nanoflower’ composites for high-performance supercapacitors

CeO(2) nanoparticles/graphene nanocomposite is fabricated by depositing CeO(2) nanoparticles onto three-dimensional graphene material and its supercapacitor performance is further investigated. The nanocomposite shows a high specific capacitance and power density, demonstrating a strong synergistic effect possibly contributed from improved conductivity of CeO(2) and better utilization of graphene.

High performance organic-inorganic hybrid material with multi-color change and high energy storage capacity for intelligent supercapacitor application

The theory underlying a novel method of gas compression driven by shear flow for next generation turbo-machinery is presented. The concept is based on the conversion of shaft power into hydrodynamic pressure and fluid flow that occur in the shear flow between a smooth rotating disk and a compliant surface counterface. This also holds for the inverse process, where gas expansion through the gap between the compliant surface and a shaft-mounted disk converts gas pressure into rotating power and torque. This is a logical evolutionary step that leverages the proven functionality of self-actuated fluid film compliant foil bearings and seals which operate in the hydrodynamic regime. Thus, as in these devices, the process of compression induced by shear flow is dominated by the balance between pressure and viscous forces which are in turn enhanced and controlled by tribological effects arising between the fluid film and the geometry of the counterface compliant surface. A model based on the compressible Reynolds equation coupled to the thin-plate theory formulation for compliant foil deflection is presented and parametrically solved to predict pressure, flow rate, and shear losses. The smooth disk and four-pad (sectored) compliant counterface effective size (7.6 mm < r < 14.1 mm), disk operating speed (50,000 to 360,000 rpm), nominal initial gap (0.03 mm < h0 < 0.635 mm), and overall operating conditions chosen for the parametric study correspond to those envisioned for eventual practical integration of miniaturized external combustion bladeless gas turbine engines and turbocompressors. Theoretical performance curves reporting flow versus pressure as well as compression power requirements versus speed were obtained. The predictions of the analysis are compared to results obtained experimentally on a proof of concept engine and presented in a companion paper. The simplicity of the bladeless geometry makes it amenable to deployment in multistage configurations, so that in conjunction with its foil bearing predecessors, this novel technology will result in low cost, ultra-high speed, high specific power and power density, high efficiency, oil-free and maintenance-free engines — attractive for many practical applications, ranging from military micro-UAV propulsion and portable power systems, to domestic combined heat and power turboalternators, and even micro-compressors for portable medical devices. As a point of reference, it is anticipated that a 10-stage bladeless compressor based on a compression stage as described herein would have a size comparable to that of a 355 mL soda can delivering a flow of 1 kg/min of compressed air.

COF-derived Co nanoparticles@N-doped carbon electrocatalysts for high performance Zn-air batteries

Molten salt-mediated hierarchical porous carbon derived from biomass waste for high-performance capacitive storage