Although most lithium ion batteries employ carbon in various forms such as graphite, hard carbon and microspheres, as an anode material; carbon has the low charge-discharge capacity up to 372 mAh/g. Silicon is one of the most attractive material to replace the carbon anode because it is abundant and has the high charge-discharge capacity up to 4200 mAh/g. Fully lithiated silicon is 4 times larger in volume than Si and such significant increase in volume causes fracture and pulverization of the electrode, thereby leading to capacity degradation and failure of battery cells. Recent studies showed that carbon-silicon composite material is effective to solve the silicon related problems. Here we employ SiC nanoparticles as an anode material [1]. Surface carbonization of silicon nanopartciles was performed using double multi-hollow discharges, where nanoparticle generation and the surface carbonization were independently controlled with the double multi-hollow discharges. Silicon nanoparticles were produced by the multi-hollow discharges of H2 + SiH4multi-hollow discharge plasma. CHx radicals for carbonization, which was produced by the CH4 multi-hollow discharge plasma, were irradiated to nanoparticles during their transportation to the downstream region. The electrolyte was 1M LiPF6 in ethylene carbonate (EC)/ dimethylene carbonate (DMC) (1:2). For measurements of anode properties, a Li metal sheet of 1 mm in thickness was used as a cathode [2]. Li intercalation capacity was measured with a constant current of 0.1 mA/mg. Charge-discharge capacity of the SiC nano-composite anode of the first cycle was 3000 mAh/g, which is 9 times higher than the capacity of graphite anode. SiC nano-particle-composite anode produced by plasma CVD is promising for lithium ion batteries. Lithium-ion batteries will play the most important role in the future of electric energy storage applications, including hybrid and electric vehicles over the next five years.

Work partly supported by Regional Innovation Strategy Support Program，MEXT.

[1] G. Uchida, et al., Jpn. J. Appl. Phys. 51 (2011) 01AD01-1.

[2] T. Ishihara, et al., Electrochem. Solid-State Lett., 10 (2007) A74.