Hata, Toshimitsu

Kyoto University Research Information Repository

TitleLithium insertion characteristics of carbonized Sugi(Cryptomeria japonica) wood sintered under high pressureAuthor(s)Hata, ToshimitsuCitationSustainable humanosphere : bulletin of Research Institute forSustainable Humanosphere Kyoto University (2009), 5: 10-10Issue Date2009-09-10URL http://hdl.handle.net/2433/182172RightType Departmental Bulletin PaperTextversionpublisherKyoto UniversityRECENT RESEARCH ACTIVITIESLithium insertion characteristics of carbonized Sugi (Cryptomeria japonica) wood                        sintered under high pressure(Laboratory of Innovative Humano-habitability, RISH, Kyoto University)Toshimitsu Hata    Much attention has focused on the development of negative electrode for lithium-ion batteries usingnanostmtured carbons that have high storage capacity [1-3, Figure 1], as intrinsic irreversible capacity andhigh hysteresis have limited their practical application [4, 5]. The present paper reports on the effects oftemperature during carbonization treatment, particle size and sintering conditions on the lithium insertioncharacteristics ofthe wood-based material.    Sugi (Cryptomeria japonica) wood was first carbonized in an electric furnace at 5000C and 7000Cunder argon at a heating rate of4 OCImin. The carbonized wood was then sintered under vacuum in a pulsecurrent sintering apparatus at up to 10500C for 15 min. The resulting carbon material was investigated in atwo-electrode cell against metallic lithium using 1 M LiPF6 in ECDEC as the electrolyte. The effects oftextural and chemical characteristics of the material on electrochemical performance, including reversibleand irreversible capacities, and cycleability, were analysed.    Our data showed a beneficial effect of optimizing the parameters such as the precarbonizationtreatment, the material particle size and the sintering process on improving the electrochemicalperformance of lithium cells. The materials sintered under high pressure showed a decrease in theirirreversible capacity compared with materials prepared with a binder on a Cu foil. Although wood char isgenerally considered to consist of hard carbons, the galvanostatic characteristics of sintered carbons arevery similar to those of soft carbons. The most effective sample (having the lowest irreversible capacityand highest reversible capacity) was prepared at 7000C with a particle size of 45-63 pm before sinteringunder pressure. Future studies will examine the porous texture of these materials in performing N2adsorption at 77K, in order to understand the effect of pressure during sintering and to further optimizetheir electrochemical perfomiance.                                                              eAcknowledgements ..G,,.,T .:•:EAideSefa,r,Chs,)l•(,a.S,ifiC,arrke,d,,,O,:`hW(l'`sh3s8PoP79rtfr.fr.OMthg ..'.iil                                                         -- -l)if(iJnaiBgrt. Of EdUCation, Culture, Sports, Science and Technology )                                                        e-eReferences                                                         ixq[1] Dominko, R., M. Gabergeek, J. Drofenik, M. Bele, S. Figure 1.Pejovnik, Electrochemical and Solid-State Letters 4(1 1) ( 2001) lithium 'A87-A190.[2] Letellier, M., F. Chevallier, C. Clinard, E. Frackowiak, J.-N. Rouzaud,Physics 118(13) (2003) 6038-6045.[3] Beguin F., F. Chevallier, C. Vix-Guterl, S. Saadallah, V. Bertagna, J.N.Carbon 43 (2005) 2160-2167.[4] Frackowiak E., F. B6guin, Carbon 40(2002) 1775-1787.[5] Beguin F., F. Chevallier, C. Vix, S. Saadallah, J.N. Rouzaud, E. Frackowiak, JournalChemist,yofSolids 65(2004)211-217.       Blethctrtse   Electrodeion cells.+  ilehMqreactlons mF. Beguin, .Journa l of ChemicalRouzaud, E. Frackowiak.ofPhysics and10

Lithium insertion characteristics of carbonized Sugi (Cryptomeria japonica) wood sintered under high pressure

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Lithium insertion characteristics of carbonized Sugi (Cryptomeria japonica) wood sintered under high pressure

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