Colloidal Crystal-Templated Porous Carbon as a High Performance Electrical Double-Layer Capacitor Material

Moriguchi, Isamu; Nakahara, Fumihiro; Furukawa, Hiroshi; Yamada, Hirotoshi; Kudo, Tetsuichi

doi:10.1149/1.1756491

Cited by 78 publications

(60 citation statements)

References 13 publications

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“…Nanoporous carbons with an average pore diameter of 110 or 450 nm were obtained by a SiO 2 -opal template process as previously reported. 11,12 An inorganic source solution for LiMnPO 4 synthesis was prepared by dissolving LiH 2 PO 4 and Mn(CH 3 COO) 2 ¢4H 2 O in diethylene glycol with the molar ratio of Li/Mn/P = 1/1/1, in which a small amount of nitric acid was added to yield a clear solution. 0.2 g of the nanoporous carbon was dispersed in 20 mL of the inorganic source solution, then the solution was subjected to microwave irradiation (2.45 GHz, 400 W) for several minutes.…”

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Rapid Synthesis and Charge–Discharge Properties of LiMnPO4 Nanocrystallite-embedded Porous Carbons

Aono¹,

Urita²,

Yamada³

et al. 2012

Chemistry Letters

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LiMnPO 4 nanocrystallite-embedded porous carbons were successfully synthesized within a few minutes by a microwaveheating process. The nanocomposites showed higher charge discharge capacity and better rate capability than bulk-LiMnPO 4 particles synthesized in a similar manner without porous carbons.Olivine-type lithium metal phosphates have attracted much attention as a potential cathode material for secondary lithiumion batteries due to the relatively high theoretical capacity (ca. 170 mA h g ¹1 ) as well as thermal and electrochemical stabilities. However, these materials have intrinsically poor electronic conductivity and Li-ion diffusivity, and hence poor rate capability.1 Down sizing Li host particles is effective to overcome the latent problem of LiFePO 4 2,3 but not enough for LiMnPO 4 having much lower conductivity of than LiFePO 4 . 4,5 It was reported that the poor rate capability of LiMnPO 4 is ascribable to a large kinetic barrier at the mismatched interface of MnPO 4 / LiMnPO 4 during Li insertion/extraction processes and that down sizing the olivine particle to nanometer level would be effective to lower the kinetic barrier.6 Since LiMnPO 4 is expected to have higher energy density than LiFePO 4 due to its higher redox potential of 4.1 V vs. Li/Li + (3.5 V vs. Li/Li + for LiFePO 4 ), various methods to synthesize nanosized LiMn-PO 4 particles have been developed in recent years for achieving reasonable capacity and rate. However, there is still a problem of poor electronic conductivity in the electrode because strong agglomeration of nanosized particles prevents homogeneous mixing with a conductive additive such as carbon black. The present study shows the first attempt for synthesis of LiMnPO 4 nanocrystallites in the nanopores or on the pore walls of nanoporous carbons. Here the nanoporous carbon provides electron-conduction and ion-transport paths in the composite. Indeed it has been recently reported that nanoporous composites of TiO 2 /CNTs and V 2 O 5 /porous carbon exhibited excellent rate of Li insertion/extraction.79 Therefore, the present composite is expected to facilitate electrochemical reactions of LiMnPO 4 nanocrystallites. In addition, the present study succeeded in a rapid synthesis of LiMnPO 4 nanocrystallites within a few minutes through a local heating of carbon framework using a microwave irradiation, contrasting the reported synthetic processes such as a conventional solid-state, 1 solgel, 5 and polyol 10 methods requiring several hours to produce LiMnPO 4 crystals. Although colloidal crystal-derived porous carbons were employed here as a representative carbon framework, the present methodology is applicable in principle to various porous carbons such as activated carbons which can be easily obtained. Nanoporous carbons with an average pore diameter of 110 or 450 nm were obtained by a SiO 2 -opal template process as previously reported.11,12 An inorganic source solution for LiMnPO 4 synthesis was prepared by dissolving LiH 2 PO 4 and Mn(CH 3 COO) 2 ¢4H 2 O in diethylene glyco...

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“…Specific surface area (S a ) and carbon content of the samples are listed in Table 1. The S a values were determend by the ¡ s -plot analysis using the subtracting pore effect (SPE) from N 2 adsorption isotherms, 11 , respectively. This means that LMP nanocrystallites were produced preferentially in nanopores of porous carbons.…”

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Rapid Synthesis and Charge–Discharge Properties of LiMnPO4 Nanocrystallite-embedded Porous Carbons

Aono¹,

Urita²,

Yamada³

et al. 2012

Chemistry Letters

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“…Such nanoporous composites are expected to provide a high surface area interface of electrolyteactive material for increasing the chargetransfer rate and active material nanophases in the nanothick wall for reducing the Li-diffusion length, as well as electron and ion conducting paths by way of carbon phases in the wall and nanopores, respectively. 2,19,20 It is demonstrated for the first time that the ordered nanoporous composites show excellent ratecapability not only for LiFePO 4 but also for LiMnPO 4 . Nanoporous composites of LiMPO 4 (M = Fe, Mn) and carbon were synthesized by a polystyrene (PS) opal-template process as follows: A PS opal was obtained by centrifuging a monodispersed PS latex with a particle size of 190 nm (Seradyn Inc.) and subsequent drying in vacuo for 1 day.…”

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3D-ordered Nanoporous LiMPO4 (M = Fe, Mn)–Carbon Composites with Excellent Charging–Discharging Rate-capability

Moriguchi¹,

Nabeyoshi²,

Izumi³

et al. 2012

Chemistry Letters

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Highly ordered and three-dimensionally interconnected nanoporous materials, constructed with a nanothick wall of LiMPO 4 (M = Fe, Mn) and a carbon (C) nanocomposite, were successfully synthesized by a colloidal crystal-template process. It was demonstrated for the first time that the ordered nanoporous composites show excellent rate capability not only for LiFePO 4 but also for LiMnPO 4 .The recent progress in chemical fabrication of nanomaterials has prompted increased interest in nanoscale optimization of photo-and electrochemical functional materials, catalysts, and so on. Synthesis of Li-host nanoparticles is actually one of the recent research trends for yielding high-power Li-ion batteries. 14The down-sizing of Li-host materials is expected to shorten the Li-diffusion length in the solid phase to reduce Li insertion extraction times. Olivine-type lithium metal phosphates have recently emerged as potential cathode materials for Li-ion batteries, because of their relatively high capacities and redox potentials, as well as their electrochemical stabilities. LiFePO 4 and LiMnPO 4 have particularly attracted a great deal of attention for their practical merits of low cost, natural abundance of Fe and Mn, and environmental benignity. However, these materials have inherently poor electronic conductivity and Li-ion diffusivity and hence poor rate-capability.5 Down-sizing of Li-host particles and their carbon coatings were effective in overcoming the latent problem for LiFePO 4 3,59 but not enough for LiMnPO 4 , having much lower conductivity than LiFePO 4 .1012 Since LiMnPO 4 theoretically has a higher energy density than LiFePO 4 because of its higher redox potential of 4.1 V vs. Li/Li + (3.5 V for LiFePO 4 ), recent studies have focused on improving the charge discharge properties of LiMnPO 4 by nanometer level structural control. 4,1317 It was reported that LiMnPO 4 nanocrystallites embedded in porous carbon show good rate capability as a result of an extension of the solid solution region in the LiMnPO 4 nanocrystallites, which lowers the kinetic barrier of the MnPO 4 LiMnPO 4 phase transition during Li insertionextraction.18 Therefore, precise control of the nanocomposite structure composed of LiMnPO 4 and carbon is expected to bring about a high capacity and rate for LiMnPO 4 -based materials.Herein, we have newly developed ordered nanoporous materials with a three-dimensionally continuous nanothick wall composed of LiMPO 4 (M = Fe, Mn) and carbon. Such nanoporous composites are expected to provide a high surface area interface of electrolyteactive material for increasing the chargetransfer rate and active material nanophases in the nanothick wall for reducing the Li-diffusion length, as well as electron and ion conducting paths by way of carbon phases in the wall and nanopores, respectively. 2,19,20 It is demonstrated for the first time that the ordered nanoporous composites show excellent ratecapability not only for LiFePO 4 but also for LiMnPO 4 . Nanoporous composites of LiMPO 4 (M = Fe, Mn) and carbon ...

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“…A nanoporous carbon with an 65 average pore diameter of 120 nm, 45 nm or 18 nm, which was obtained by a silica opal template process as previously reported, 21 was used for the above syntheses. Hereafter the porous carbon and the SnO2-embedded nanoporous carbon composites obtained by [1] and [2] methods are denoted as CX,…”

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Enhanced charge–discharge properties of SnO₂ nanocrystallites in confined carbon nanospace

2014

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Almost perfect embedding of SnO2 nanocrystallites in carbon nanopores was achieved by in situ synthesis using vaporized SnCl2 and silica opal-derived nanoporous carbons. The reversibility of SnO2-Sn conversion and Sn-Li alloying/dealloying reactions was greatly enhanced by the confinement in 10 regulated carbon nanospace.Much research work has been devoted to the development of energy storage devices with both high energy and high power densities due to expected demand for power-grid applications as well as power sources of electric and/or hybrid electric vehicle. 15Lithium-ion secondary batteries (LIBs) are attractive power storage devices, but they still need to be further improved for the power use. Enhancement of capacities and cycleability of electrode materials is one of the tactics to improve the LIB performance. With respect to the LIB anode materials, based materials have been studied as a candidate of large capacity anode alternative to the present graphite or carbon anode. However, the electrochemical reactions of SnO2 with Li ions, which are composed of following reactions (1) and (2), are generally irreversible, and thus cause severe capacity fading 25 during cycling.Conversion reactions: SnO2 + 4 Li + + 4 e − ↔ Sn + 2 Li2O (1) Alloying/de-alloying reactions: Sn + x Li + + x e − ↔ LixSn (2) Some researchers have tried to overcome the problem from the approaches of down-sizing of SnO2 particles 1-5 and controlling 30 the morphology of SnO2 such as nanowires, 6 nanotubes 7,8 and nanospheres. 9-12 Some of them succeeded in yielding relatively high initial capacities, but the capacity retention was not improved enough due to cracking and crumbling in the SnO2-integrated electrodes caused by the volume change during Li 35 insertion and extraction. Nanocomposites of SnO2 and carbon nanomaterials such as mesoporous carbons, 13-15 carbon nanotubes 16,17 and graphene sheets [18][19][20] were effective to suppress the mechanical degradation and showed high capacities and a cycleability improved to some extent. The reported charge-40 discharge capacities of nanocomposites are including electric double layer capacities and/or Li intercalation/de-intercalation capacities of graphite phase, thus it is unclear how much the electrochemical reactions of SnO2 with Li ions contributed to the total capacities and the capacity retentions. In order to achieve 45 high performance of SnO2 electrode materials, it is essentially important to clarify the reversibility of electrochemical reactions of SnO2 with Li ions and which structure is suitable for improving the performance.Since the reported nanocomposites have heterogeneous 50 structures where SnO2 nanoparticles are incorporated in irregular interspace and inner pores of carbon nanomaterials and also are deposited on the outer surfaces of them, it is difficult to evaluate exactly the SnO2 reactions affected significantly by the reaction space. In the present study, we have succeeded in almost perfect 55 embedding of SnO2 nanocrystallites in the regulated carbon nano...

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Colloidal Crystal-Templated Porous Carbon as a High Performance Electrical Double-Layer Capacitor Material

Cited by 78 publications

References 13 publications

Rapid Synthesis and Charge–Discharge Properties of LiMnPO4 Nanocrystallite-embedded Porous Carbons

Rapid Synthesis and Charge–Discharge Properties of LiMnPO4 Nanocrystallite-embedded Porous Carbons

3D-ordered Nanoporous LiMPO4 (M = Fe, Mn)–Carbon Composites with Excellent Charging–Discharging Rate-capability

Enhanced charge–discharge properties of SnO₂ nanocrystallites in confined carbon nanospace

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Colloidal Crystal-Templated Porous Carbon as a High Performance Electrical Double-Layer Capacitor Material

Cited by 78 publications

References 13 publications

Rapid Synthesis and Charge–Discharge Properties of LiMnPO4 Nanocrystallite-embedded Porous Carbons

Rapid Synthesis and Charge–Discharge Properties of LiMnPO4 Nanocrystallite-embedded Porous Carbons

3D-ordered Nanoporous LiMPO4 (M = Fe, Mn)–Carbon Composites with Excellent Charging–Discharging Rate-capability

Enhanced charge–discharge properties of SnO2 nanocrystallites in confined carbon nanospace

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Enhanced charge–discharge properties of SnO₂ nanocrystallites in confined carbon nanospace