酸化鉄粉末を添加したリチウム二次電池高容量SiO-C負極の電気化学特性

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The anode properties of SiO-C electrode materials [SiO-C:α-Fe2O3 = x:100 − x (wt%)] containing α-Fe2O3 fine powder (spherical particles, ca. 0.16 µm) as the additive were investigated in a lithium cell using lithium metal as the counter electrode. It was observed by scanning electron microscopy (SEM) that spherical α-Fe2O3 particles are present between the SiO-C particles. The SiO-C alloying-reaction electrode exhibited a high capacity of ca. 1330 mAh g−1. However, the electrode caused a gradual decrease in cycle capacity at around 30 cycles. On the other hand, the α-Fe2O3 conversion-reaction electrode showed a high discharge capacity of ca. 800 mAh g−1, and a good cycle performance over 50 cycles. In addition, charge and discharge were possible even for an α-Fe2O3 electrode without the addition of an electronic conductive material such as carbon. SiO-C electrodes containing a small amount of α-Fe2O3 fine powder exhibited higher capacities and improved cycle performances compared with the SiO-C electrode. The electrode with x = 50 exhibited a discharge capacity of ca. 1000 mAh g−1 and a good cycle performance over 70 cycles. The α-Fe2O3 fine powder works as a conductive path between the SiO-C particles, and prevents the disintegration of the electrode.