A mesoporous carbon with regular three-dimensionally interconnected 2 nm pore arrays using AlMCM-48 as a template has been synthesised; the mesoporous carbon exhibited excellent performance as an electrochemical double layer capacitor.

The electric double-layer capacitor (EDLC) has been considered as a promising high power energy source for digital communication devices and electric vehicles. The advantageous features of the EDLC are its better rate capability and longer cycle life as compared to modern secondary batteries. EDLC utilizes the double layer formed at electrode/electrolyte interface where electric charges are accumulated on the electrode surfaces and ions of opposite charge are arranged in the electrolyte side. EDLC electrode materials should thus have a large surface area for charge accumulation, and should have an appropriate pore structure for electrolyte wetting and rapid ionic motion. At present, activated carbons or molecular-sieving carbons are used as the EDLC electrode materials. Even if these conventional carbons have a large surface area, their EDLC application is rather limited because they contain pores ranging from micropores (<2 nm diam) to macropores and the pores are randomly connected. 1 The micropores are not easily wetted by electrolytes, and the exposed surface in micropores may not be utilized for charge storage. Moreover, even in the situation wherein the micropores are wetted by electrolyte, ionic motion in such small pores may be so slow that the high rate capability, which is one of the advantages of EDLCs, may not be realized. 1 Both charge storage and rate capability are further limited if the pores are randomly connected. The blind or isolated pores may not be wetted by electrolytes and irregular pore connection makes ionic motion difficult. 2,3 Therefore, high-surface-area carbon materials containing regularly interconnected mesopores (>2 nm) are highly desirable for the EDLC electrode.Recently, we have synthesized a new mesoporous carbon (NMC) that appears to generally meet the above requirements. It was prepared via the template route, in which the mesoporous aluminosilicates were utilized as the template. 4,5 Phenol resin was prepared inside the pores of the template and carbonized. Mesoporous carbon with three-dimensionally interconnected ca. 2 nm pores was obtained after removing the inorganic template with a hydrofluoric acid treatment.As an extension of our previous report, this paper deals with the physicochemical properties of NMC and its EDLC performance. The pore structure and electrical conductivity of NMC were measured, and its EDLC performance characteristics including the capacitance and rate capability were analyzed. Similar measurements were carried out with a molecular-sieving carbon (MSC25) that has random cage-like micropores (<2 nm), and the effect of pore size and pore connection pattern on EDLC performances of carbon materials was discussed. ExperimentalMaterials.-The synthetic procedure for NMC was provided in our preliminary report. 4 For the synthesis, a mesoporous aluminosilicate identified as Mobile Composite Material 48 (MCM48) was used as the template. The molecular-sieving carbon (MSC25) provided by Kansai Coke and Chemicals has a specific Brunauer, Emmett, and Teller (B...

Recently, hybrid supercapacitors (HSCs), which combine the use of battery and supercapacitor, have been extensively studied in order to satisfy increasing demands for large energy density and high power capability in energy-storage devices. For this purpose, the requirement for anode materials that provide enhanced charge storage sites (high capacity) and accommodate fast charge transport (high rate capability) has increased. Herein, therefore, a preparation of nanocomposite as anode material is presented and an advanced HSC using it is thoroughly analyzed. The HSC comprises a mesoporous Nb2O5/carbon (m-Nb2O5-C) nanocomposite anode synthesized by a simple one-pot method using a block copolymer assisted self-assembly and commercial activated carbon (MSP-20) cathode under organic electrolyte. The m-Nb2O5-C anode provides high specific capacity with outstanding rate performance and cyclability, mainly stemming from its enhanced pseudocapacitive behavior through introduction of a carbon-coated mesostructure within a voltage range from 3.0 to 1.1 V (vs Li/Li(+)). The HSC using the m-Nb2O5-C anode and MSP-20 cathode exhibits excellent energy and power densities (74 W h kg(-1) and 18,510 W kg(-1)), with advanced cycle life (capacity retention: ∼90% at 1000 mA g(-1) after 1000 cycles) within potential range from 1.0 to 3.5 V. In particular, we note that the highest power density (18,510 W kg(-1)) of HSC is achieved at 15 W h kg(-1), which is the highest level among similar HSC systems previously reported. With further study, the HSCs developed in this work could be a next-generation energy-storage device, bridging the performance gap between conventional batteries and supercapacitors.

Hybrid supercapacitors (battery-supercapacitor hybrid devices, HSCs) deliver high energy within seconds (excellent rate capability) with stable cyclability. One of the key limitations in developing high-performance HSCs is imbalance in power capability between the sluggish Faradaic lithium-intercalation anode and rapid non-Faradaic capacitive cathode. To solve this problem, we synthesize Nb2O5@carbon core-shell nanocyrstals (Nb2O5@C NCs) as high-power anode materials with controlled crystalline phases (orthorhombic (T) and pseudohexagonal (TT)) via a facile one-pot synthesis method based on a water-in-oil microemulsion system. The synthesis of ideal T-Nb2O5 for fast Li(+) diffusion is simply achieved by controlling the microemulsion parameter (e.g., pH control). The T-Nb2O5@C NCs shows a reversible specific capacity of ∼180 mA h g(-1) at 0.05 A g(-1) (1.1-3.0 V vs Li/Li(+)) with rapid rate capability compared to that of TT-Nb2O5@C and carbon shell-free Nb2O5 NCs, mainly due to synergistic effects of (i) the structural merit of T-Nb2O5 and (ii) the conductive carbon shell for high electron mobility. The highest energy (∼63 W h kg(-1)) and power (16 528 W kg(-1) achieved at ∼5 W h kg(-1)) densities within the voltage range of 1.0-3.5 V of the HSC using T-Nb2O5@C anode and MSP-20 cathode are remarkable.

Template synthesis of porous materials is one of the most intensively studied research areas in materials chemistry. Since the development of M41S materials by Mobil Oil researchers in 1992, [1,2] many different mesoporous inorganic materials have been prepared using various types of organ-ic templates. [3±6] Porous polymeric and carbon materials have been synthesized using inorganic templates. [7±9] Many porous carbons have been extensively applied in separation and purification technology. [10] They are also used as catalytic supports, chromatography columns, and electrode materials for batteries and capacitors. [11±13] These porous carbons are usually microporous and the production of larger pore-sized mesoporous carbons has been intensively pursued for applications in separation of bulky organic materials and electrode materials. Recently, we have developed new preparative methods to produce mesoporous carbons using inorganic templates such as surfactant-stabilized silica sol particles [14] and mesoporous MCM-48. [15] In particular, the carbon material produced using the MCM-48 template exhibited interesting electrochemical doublelayer capacitance (EDLC) behavior, resulting from regular 3D interconnected mesopores. Difficulty in the synthesis of the template MCM-48 material, however, would hamper the extensive application of mesoporous carbon material. Herein we report the synthesis of a new mesoporous carbon using hexagonal mesoporous silica (HMS) aluminosilicate as a template. With the knowledge gained from this research, we could indirectly elucidate the pore structure of HMS. We also present preliminary results on the EDLC performance of the material.HMS has several advantages over MCM-48 from a synthetic viewpoint: 1) the use of cheap primary alkyl amines as the structure-directing agent; 2) a higher silica recovery yield (>95 %) than MCM-48 (~50 %); 3) a shorter synthesis time (18 h for HMS and 4 days for MCM-48); and 4) no hydrothermal reaction. [16,17] In the first report on HMS the authors claimed that the pore structure of the silica material is similar to that of well-known hexagonal mesoporous MCM-41, but with a much smaller scattering domain size. The small domain size enabled formation of textural pores, along with framework pores from the template. In a later publication, the same group suggested a wormhole-like pore structure for HMS based on transmission electron microscopy (TEM). [17] The pore structure and the pore connectivity of HMS have not yet been elucidated. The pore connectivity of mesoporous materials is important in catalytic and electrochemical applications. By changing the polarity of the reaction solvent, HMS with dominant framework pores has also been synthesized. In our study HMS silica with predominant framework pores (negligible textural pores) has been utilized as a template.The synthetic procedure for the synthesis of mesoporous carbon using HMS as a template is as follows: HMS was prepared by the reported method using the starting reaction mixture in a molar rati...