[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Supercapacitors have drawn considerable attention in recent years due to their high specific power, long cycle life, and ability to bridge the power/energy gap between conventional capacitors and batteries/fuel cells. Nanostructured electrode materials have demonstrated superior electrochemical properties in producing high-performance supercapacitors. In this review article, we describe the recent progress and advances in designing nanostructured supercapacitor electrode materials based on various dimensions ranging from zero to three. We highlight the effect of nanostructures on the properties of supercapacitors including specific capacitance, rate capability and cycle stability, which may serve as a guideline for the next generation of supercapacitor electrode design.

/pdf/supercapacitor-electrode-materials-nanostructures-from-0-to-3zlm6qeqf5.pdf

Supercapacitor electrode materials: nanostructures from 0 to 3 dimensions

Hybrid quantum circuits combine two or more physical systems, with the goal of harnessing the advantages and strengths of the different systems in order to better explore new phenomena and potentially bring about novel quantum technologies. This article presents a brief overview of the progress achieved so far in the field of hybrid circuits involving atoms, spins, and solid-state devices (including superconducting and nanomechanical systems). How these circuits combine elements from atomic physics, quantum optics, condensed matter physics, and nanoscience is discussed, and different possible approaches for integrating various systems into a single circuit are presented. In particular, hybrid quantum circuits can be fabricated on a chip, facilitating their future scalability, which is crucial for building future quantum technologies, including quantum detectors, simulators, and computers.

/pdf/hybrid-quantum-circuits-superconducting-circuits-interacting-52djng19hs.pdf

Hybrid quantum circuits: Superconducting circuits interacting with other quantum systems

Notably, many significant breakthroughs for a new generation of supercapacitors have been reported in recent years, related to theoretical understanding, material synthesis and device designs. Herein, we summarize the state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors. Firstly, fundamental understanding of the mechanism is mainly focused on the relationship between the structural properties of electrode materials and their electrochemical performances based on some in situ characterization techniques and simulations. Secondly, some emerging electrode materials are discussed, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), MXenes, metal nitrides, black phosphorus, LaMnO3, and RbAg4I5/graphite. Thirdly, the device innovations for the next generation of supercapacitors are provided successively, mainly emphasizing flow supercapacitors, alternating current (AC) line-filtering supercapacitors, redox electrolyte enhanced supercapacitors, metal ion hybrid supercapacitors, micro-supercapacitors (fiber, plane and three-dimensional) and multifunctional supercapacitors including electrochromic supercapacitors, self-healing supercapacitors, piezoelectric supercapacitors, shape-memory supercapacitors, thermal self-protective supercapacitors, thermal self-charging supercapacitors, and photo self-charging supercapacitors. Finally, the future developments and key technical challenges are highlighted regarding further research in this thriving field.

Latest advances in supercapacitors: from new electrode materials to novel device designs.

A mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented. Our calculation, which traverses the weak- to strong-segregation regimes, is free of traditional approximations. Regions of stability are determined for disordered (DIS) melts and for ordered structures including lamellae (L), hexagonally packed cylinders (H), body-centered cubic spheres (QIm3m), close-packed spheres (CPS), and the bicontinuous cubic network with Ia3d symmetry (QIa3d). The CPS phase exists in narrow regions along the order−disorder transition for χN ≥ 17.67. Results suggest that the QIa3d phase is not stable above χN ∼ 60. Along the L/QIa3d phase boundaries, a hexagonally perforated lamellar (HPL) phase is found to be nearly stable. Our results for the bicontinuous Pn3m cubic (QPn3m) phase, known as the OBDD, indicate that it is an unstable structure in diblock melts. Earlier approximation schemes used to examine mean-field behavior are reviewed, and compa...

Unifying Weak- and Strong-Segregation Block Copolymer Theories

The industrial artificial fixation of atmospheric N-2 to NH3 is carried out using the Haber-Bosch process that is not only energy-intensive but emits large amounts of greenhouse gas. Electrochemical reduction offers an environmentally benign and sustainable alternative for NH3 synthesis. Although Mo-dependent nitrogenases and molecular complexes effectively catalyze the N-2 fixation at ambient conditions, the development of a Mo-based nanocatalyst for highly performance electrochemical N-2 fixation still remains a key challenge. Here, greatly boosted electrocatalytic N-2 reduction to NH3 with excellent selectivity by defect-rich MoS2 nanoflowers is reported. In 0.1 m Na2SO4, this catalyst attains a high Faradic efficiency of 8.34% and a high NH3 yield of 29.28 mu g h(-1) mg(cat.)(-1) at (-)0.40 V versus reversible hydrogen electrode, much larger than those of defect-free counterpart (2.18% and 13.41 mu g h(-1) mg(cat.)(-1)), with strong electrochemical stability. Density functional theory calculations show that the potential determining step has a lower energy barrier (0.60 eV) for defect-rich catalyst than that of defect-free one (0.68 eV).

Boosted Electrocatalytic N2 Reduction to NH3 by Defect-Rich MoS2 Nanoflower

Li-ion hybrid capacitors (LIHCs), consisting of an energy-type redox anode and a power-type double-layer cathode, are attracting significant attention due to the good combination with the advantages of conventional Li-ion batteries and supercapacitors. However, most anodes are battery-like materials with the sluggish kinetics of Li-ion storage, which seriously restrict the energy storage of LIHCs at the high charge/discharge rates. Herein, vanadium nitride (VN) nanowire is demonstated to have obvious pseudocapacitive characteristic of Li-ion storage and can get further gains in energy storage through a 3D porous architecture with the assistance of conductive reduced graphene oxide (RGO). The as-prepared 3D VN–RGO composite exhibits the large Li-ion storage capacity and fast charge/discharge rate within a wide working widow from 0.01–3 V (vs Li/Li + ), which could potentially boost the operating potential and the energy and power densities of LIHCs. By employing such 3D VN–RGO composite and porous carbon nanorods with a high surface area of 3343 m 2 g −1 as the anode and cathode, respectively, a novel LIHCs is fabricated with an ultrahigh energy density of 162 Wh kg −1 at 200 W kg −1 , which also remains 64 Wh kg −1 even at a high power density of 10 kW kg −1 .

Fast and Large Lithium Storage in 3D Porous VN Nanowires–Graphene Composite as a Superior Anode Toward High‐Performance Hybrid Supercapacitors

A series of hybrid electrochemical capacitors were fabricated by using the flower-like cobalt hydroxide (Co(OH)2) and urchin-like vanadium nitride (VN) as the positive and negative electrode materials, respectively. Both Co(OH)2 and VN electrode materials showed excellent electrochemical performance due to their unique structure and fast reversible Faradic reaction characteristics. With different operation voltage window (OVW) and negative/positive mass ratios, the impact on capacitance performance of the hybrid supercapacitor was investigated thoroughly, which demonstrated that both mass ratio and OVW played an important role in their capacitance performance. Furthermore, theoretical modeling was performed and the simulation result was found to be in agreement with the experimental result for the influence of the negative/positive mass ratio on capacitance performance of the hybrid supercapacitor. When an optimized negative/positive mass ratio was located, the Co(OH)2//VN hybrid supercapacitor could be cycled reversibly in the high-voltage region of 0–1.6 V and delivered a high energy density of 22 W h kg−1. Even at a large power density of 15.9 kW kg−1, the hybrid supercapacitor still possessed a desirable specific energy density of 9 W h kg−1. Such an impressive hybrid supercapacitor was expected to be a highly promising candidate for application in high-performance energy storage systems.

A hybrid supercapacitor based on flower-like Co(OH)2 and urchin-like VN electrode materials

Vertically aligned nickel–cobalt oxide (NCO) nanosheets with porous structure were successfully synthesized on FTO substrates by a simple electrochemical method without any templates. Cyclic voltammetry (CV) and galvanostatic charge/discharge measurements show that the porous NCO nanosheets have an ideal capacitive performance and long-term stability. With an optimum amount of Ni, the specific capacitance for the NCOs could reach as high as 453 F g−1 at a scan rate of 5 mV s−1 and 506 F g−1 at a current density of 1 A g−1, showing an improvement of around 50% compared with cobalt oxide. Furthermore, a symmetric supercapacitor based on two NCO electrodes exhibits a maximum specific capacitance of 89.2 F g−1 at 0.17 A g−1.

Controllable synthesis of porous nickel–cobalt oxide nanosheets for supercapacitors

This paper presents the preparation of unique copper sulfide flakes in CTAB/n-C5H11OH/n-C6H14/water microemulsions under hydrothermal conditions at 130 °C. With the pre-addition of n-dodecanethiol to the microemulsions, much smaller hexagonal Cu2S nanodisks resulted, which self-assembled into a superlattice. The crystal phases, absorption properties, and morphologies were characterized. The formation mechanism of the unique crystals is also discussed.

Peng Zhang

Papers

Boosted Electrocatalytic N2 Reduction to NH3 by Defect-Rich MoS2 Nanoflower

Fast and Large Lithium Storage in 3D Porous VN Nanowires–Graphene Composite as a Superior Anode Toward High‐Performance Hybrid Supercapacitors

A hybrid supercapacitor based on flower-like Co(OH)2 and urchin-like VN electrode materials

Controllable synthesis of porous nickel–cobalt oxide nanosheets for supercapacitors

Copper sulfide flakes and nanodisks