Nano-graphite functionalized mesocellular carbon foam with enhanced intra-penetrating electrical percolation networks for high performance electrochemical energy storage electrode materials

다국어 초록 (Multilingual Abstract)

<P>Mesocellular carbon foam (MSU-F-C) is functionalized with hollow nanographite by a simple solution-phase method to enhance the intrapenetrating electrical percolation network. The electrical conductivity of the resulting material, denoted as MSU-F-C-G, is increased by a factor of 20.5 compared with the pristine MSU-F-C. Hollow graphite nanoparticles are well-dispersed in mesocellular carbon foam, as confirmed by transmission electron microscopy (TEM), and the <I>d</I> spacing of the (002) planes is 0.343 nm, which is only slightly larger than that of pure graphite (0.335 nm), suggesting a random combination of graphitic and turbostratic stacking. After nanographitic functionalization, the BET surface area and total pore volume decreased from 928 m<SUP>2</SUP> g<SUP>−1</SUP> and 1.5 cm<SUP>3</SUP> g<SUP>−1</SUP> to 394 m<SUP>2</SUP> g<SUP>−1</SUP> and 0.7 cm<SUP>3</SUP> g<SUP>−1</SUP>, respectively. Thermogravimetric analysis in air shows that the thermal stability of MSU-F-C-G is improved relative to that of MSU-F-C, and the one-step weight loss indicates that the nanographite is homogeneously functionalized on the MSU-F-C particles. When the resulting mesocellular carbon materials are used as electrode materials for an electric double layer capacitor (EDLC), the specific capacitances (<I>C</I><SUB>sp</SUB>) of the MSU-F-C and MSU-F-C-G electrodes at 4 mV s<SUP>−1</SUP> are 109 F g<SUP>−1</SUP> and 93 F g<SUP>−1</SUP>, respectively. The MSU-F-C-G electrode exhibited a very high area capacitance (<I>C</I><SUB>area</SUB>, 23.5 μF cm<SUP>−2</SUP>) compared with that of the MSU-F-C electrode (11.7 μF cm<SUP>−2</SUP>), which is attributed to the enhanced intraparticle conductivity by the nanographitic functionalization. MSU-F-C-G exhibited high capacity retention (52%) at a very high scan rate of 512 mV s<SUP>−1</SUP>, while only a 23% capacity retention at 512 mV s<SUP>−1</SUP> was observed in the case of the MSU-F-C electrode. When applied as an anode in a lithium ion battery, a significant increase in the initial efficiency (44%), high reversible discharge capacity (580 mA h g<SUP>−1</SUP>) in the lower voltage region, and a higher rate capability were observed. The high rate capability of the MSU-F-C-G electrode as charge storage was due to the low resistance derived from the nanographitic functionalization.</P>

<P>Graphic Abstract</P><P>Nano-graphite functionalized mesocellular carbon foam exhibits advanced electrochemical performances as electrode materials in EDLC and LIB due to the role of graphite as an intrapenetrating electrical network.
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