成果報告書詳細
管理番号20090000000787
タイトル*平成20年度中間年報 次世代自動車用高性能蓄電システム技術開発/次世代技術開発/鋳型法を利用した革新的リチウムイオン電池負極材料の開発研究
公開日2010/3/24
報告書年度2008 - 2008
委託先名国立大学法人東北大学
プロジェクト番号P07001
部署名燃料電池・水素技術開発部 蓄電技術開発室
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 1 純炭素負極材料の開発 炭素質の負極材料には大きく分けて黒鉛系と非黒鉛系があり、非黒鉛系材料は黒鉛の理論容量である372 mAh/gを超える大きな可逆容量を示す。これは、グラフェンシートの層間距離が大きい部位(すなわち細孔)にリチウムが大量に貯蔵される、キャビティ容量のためと言われている。しかし、細孔内に電解液が侵入し大量の不働態膜を形成するため不可逆容量が大きいことが欠点である。そこで本研究開発では、不働態膜の生成を防ぎ、かつ可逆容量を大きくするために、粒子外表面はイオンを通すが電解液を通さない緻密な炭素層で覆われ、粒子内部にはリチウムが高密度で貯蔵される均一な細孔だけが存在する、二重構造を持つ炭素微粒子を鋳型法を利用して合成し、そのリチウム吸蔵特性を調査することを目的とした。
英文要約Title : Lithium-Ion Battery Based on Hierarchically Designed Microporous Carbon Anodes Synthesized by Template Technique: New Energy Technology Development Program. Development of High-performance Battery System for Next-generation Vehicles (FY2008-FY2009) Annual Report
1) Synthesis of the core-shell carbon particles
As a negative electrode in lithium-ion battery, graphite has been generally used because of its stable charge-discharge performance and relatively long cycle life. However, graphite has a theoretical upper limit of the capacitance (372 mAh/g). On the other hand, some of non-graphitic carbons exhibit much larger capacitance. However, such carbons have large irreversible capacitance. In this work, microporous carbon particles were synthesized by using zeolite Y as the template. The obtained carbons have very high surface area (3610 m2/g). Moreover, the outer surface of the carbon particles was covered with dense carbon layer through a CVD process to inhibit the electrolyte solutions from getting into the carbon particles. The core-shell carbons thus obtained exhibited large capacitance and better coulomb efficiency than the pristine porous carbons.
2) Synthesis of the Si/carbon nanocomposites
Si can store much larger amount of Li than carbon materials up to 4198 mAh/g. However, Si can be easily degraded during its charge-discharge cycling. To overcome this problem, we tried to synthesize Si/carbon nanocomposite where each Si nanoparticle exists in a void of the carbon matrix. Thanks to the void surrounding the Si nanoparticle, it is expected that Si will not destroy the carbon matrix during the charge-discharge cycling. Moreover, the carbon matrix will play a role of current corrector. In order to synthesize such Si/carbon nanocomposite, we reduced SiO2 nanoparticles in the SiO2/carbon nanocomposite. As a result, Si/carbon nanocomposites were obtained after the reduction.
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