High-Capacity Characteristics of Li-S Rechargeable Battery Using CNT Electrode

Carbon nanotubes (CNTs) are good electronic conductors and have a high chemical stability. We have synthesized vertically aligned CNTs directly on nickel foils and applied them to a cathode of a lithium-sulfur (Li-S) rechargeable battery [1, 2]. The CNTs grown by our thermal CVD process have characteristically a spiral structure. CNT/S composite cathodes were fabricated by impregnating the CNT films with molten S. Figure 1 shows cycle performance and Columbic efficiency of the CNT/S composite cathode containing 8 mg cm^-2 with S content of 86 wt% in a 2032 type cell. LiTFSI (0.86 M) dissolved in DME/DOL (9:1 vol %) with LiNO₃ (3 wt%) additives was used as electrolyte. The high S loading cell retained a specific capacity of 1000 mAh g^-1 even after 50 cycles. This good performance is considered to be attributed by the spiral CNT structure which can hold the electrolyte containing the dissolved polysulfides with a little loss.

Reference

[1] T. Nozue, presented at the 2012 MRS Spring Meeting, San Francisco, 2012 (unpublished)

[2] T. Nozue, presented at The 54^th Battery Symposium, Osaka, 2013 (unpublished)