A review on the development of a porous carbon-based as modeling materials for electric double layer capacitors

Carbon electrodes are a key factor for electric double layer capacitors (EDLCs). Carbon gels have high porosity with a controllable pore structure by changing synthesis conditions and modifying preparation processing to improve the electrochemical performance of EDLCs. This review summarizes the preparation of carbon gels and their derivatives, the criteria to synthesize high surface area in each process, the development by some carbon forms, and EDLC applications. Porous carbons are also prepared as model materials by concentrating on how pore structure increases electrochemical capacitance, such as electronic and ion resistance, the tortuosity of pore channel, suitable micropore and mesopore sizes, and mesopore size distribution. This review emphasizes the significance of pore structures as the key factor to allow for the design of suitable pore structures that are suitable as the carbon electrode for EDLCs.     

High-voltage aqueous symmetric electrochemical capacitor based on Ru0.7Sn0.3O2·nH2O electrodes in 1 M KOH

A mild hydrothermal process is applied to synthesize hydrous ruthenium–tin binary oxides (Ru_0.7Sn_0.3O₂·nH₂O) with good capacitive performance in alkaline system. Then, a symmetric electrochemical capacitor (EC) is fabricated based on the as-synthesized Ru_0.7Sn_0.3O₂·nH₂O material and 1 M KOH aqueous electrolyte. Electrochemical performance of the symmetric EC is investigated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy tests. Electrochemical tests demonstrate that the symmetric EC surprisingly can operate with a high upper cell voltage limit of 1.45 V in 1 M KOH electrolyte. Maximum specific capacitance and energy density of the symmetric aqueous EC are approximately 160 F/g and 21 Wh/kg, respectively, delivered at a current density of 1.25 A/g. And the specific energy density decreases to approximately 15 Wh/kg when the specific power density increases up to approximately 1,770 W/kg. The promising specific energy and power densities are obtained simultaneously for the unwonted symmetric EC due to its larger operating potential range. Moreover, the symmetric EC exhibits electrochemical stability with 85.2% of the initial capacitance over consecutive 1,000 cycle numbers.     

基于阴离子-石墨嵌层化合物的电化学电容器

石墨可以在高电势下电化学可逆存储阴离子,有望在高电压储能器件中担当正极材料.本文介绍了基于阴离子-石墨嵌层化合物型正极材料的高比能电容器的研究进展,剖析了影响电容器性能的各方面因素,探讨了一系列表征相关电极材料储能机制的方法和手段,揭示了溶剂化效应对阴离子插嵌石墨正极电化学行为的关键性作用.并进一步概述了该种正极材料近年来在新型储能器件-双离子电池中的发展态势,展望了其应用前景和即将面临的潜在问题.     

钠离子混合电容器电极材料的研究进展

钠离子混合电容器(SIHCs)因其资源丰富和价格低廉等优点,同时具有与锂相似的物理化学性质,被认为是最具有发展前景的电化学储能器件之一。通常,SIHCs由高能量密度的阳极和高功率密度的阴极组成,可在钠离子电池和超级电容器之间搭建能量和功率的桥梁。然而,电容型正极材料和电池型负极材料之间的动力学和容量的不平衡问题成为实现其规模化应用的主要瓶颈。本文概述了SIHCs相关的工作原理和各类正、负极材料研究进展,从材料结构的可控制备和改性处理等方面对SIHCs发展趋势进行了重点评述,并讨论了SIHCs发展过程中遇到的主要挑战,最后对该领域在未来的研究方向进行了展望。     

基于电子邮件的连锁商业MIS的研究与实现

通过远程联网实现统一的进销存管理是连锁商业MIS系统的关键。文章阐述了基于电子邮件的一种连锁商业MIS联网的解决方法和相关的数据格式。实践表明本方法具备经济实用、操作维护方便等优点     

Electrical characteristics of MOS capacitor with HfTiON gate dielectric and HfTiSiON interlayer

The paper reports that HfTiO dielectric is deposited by reactive co-sputtering of Hf and Ti targets in an Ar/O₂ ambience, followed by an annealing in different gas ambiences of N₂, NO and NH₃ at 600℃ for 2 min. Capacitance--voltage and gate-leakage properties are characterized and compared. The results indicate that the NO-annealed sample exhibits the lowest interface-state and dielectric-charge densities and best device reliability. This is attributed to the fact that nitridation can create strong Si \equiv N bonds to passivate dangling Si bonds and replace strained Si--O bonds, thus the sample forms a hardened dielectric/Si interface with high reliability.     

Investigation of the Electrical and the Dielectric Properties of Various LB Films

The electrical and dielectric properties of metal-insulator-semiconductor(MIS) and metal-insulator-metal(MlM) structures of various LB films were investigated. High frequency capacitance-voltage (C-V)measurements of the MIS structures of the LB films showed the accumulation,depletion and inversion regions.The dielectric constants of various LB films were calculated. Contrast with other LB films, the microgel star-shaped amphiphile(MSA) LB film showed a potential application in electronic devices due to its higher thermal and mechanical stabilities. The breakdown voltage of the MIM structure of the MSA containing only a single monolayer is over 200 V.     

2020 roadmap on pore materials for energy and environmental applications

Porous materials have attracted great attention in energy and environment applications, such as metal organic frameworks (MOFs), metal aerogels, carbon aerogels, porous metal oxides. These materials could be also hybridized with other materials into functional composites with superior properties. The high specific area of porous materials offer them the advantage as hosts to conduct catalytic and electrochemical reactions. On one hand, catalytic reactions include photocatalytic, photoelectrocatalytic and electrocatalytic reactions over some gases. On the other hand, they can be used as electrodes in various batteries, such as alkaline metal ion batteries and electrochemical capacitors. So far, both catalysis and batteries are extremely attractive topics. There are also many obstacles to overcome in the exploration of these porous materials. The research related to porous materials for energy and environment applications is at extremely active stage, and this has motivated us to contribute with a roadmap on ‘porous materials for energy and environment applications’.     

Vacant Manganese-Based Perovskite Fluorides@Reduced Graphene Oxides for Na-Ion Storage with Pseudocapacitive Conversion/Insertion Dual Mechanisms

Na-ion capacitors (NICs) and Na-based dual-ion batteries (Na-DIBs) have been considered to be promising alternatives to traditional lithium-ion batteries (LIBs) because of the abundance and low cost of the Na-ion, but their energy density, power density and life cycle are limited. Herein, dual-vacancy (including K⁺ and F⁻ vacancies) perovskite fluoride K_0.86MnF_2.69@reduced graphene oxide (rGO; recorded as Mn−G) as anode for NICs and Na-DIBs has been developed. The special conversion/intercalation dual Na-ion energy storage mechanism and pseudocapacitive dynamics are analyzed in detail. The Mn−G//AC NICs and Mn−G//KS6 Na-DIBs delivered a maximum energy density of 92.7 and 187.6 W h kg⁻¹, a maximum power density of 20.2 and 21.12 kW kg⁻¹, and long cycle performance of 61.3 and 68.4 % after 1000 cycles at 5 A g⁻¹, respectively. Moreover, Mn−G//AC NICs and Mn−G//KS6 Na-DIBs can work well over a wide range of temperatures (−20 to 40 °C). These results make it competitive in Na-ion storage applications with high energy/power density over a wide temperature range.