Authors: Y Takeuchi T Yamashita K Kuriyama K Kushida
Publish Date: 2016/01/28
Volume: 20, Issue: 7, Pages: 1885-1888
Abstract
Li5SiN3 crystals are synthesized by direct reaction between Li3N and Si3N4 with the molar ratio Li3N/Si3N4 of 101 Reaction is performed at 1073 K for 1 h under a nitrogen atmosphere of 700 Torr The lattice constant determined by the Xray powder diffraction method is 4718 Å Four broad Raman peaks are observed at 196 286 580 and 750 cm−1 By analogy with LiMgN the broad peak at 580 cm−1 with a half width of 140 cm−1 is attributed to homogenously random distribution of Li and Si atoms The band gap of Li5SiN3 is found to be a direct gap of about 25 eV by optical absorption and photoacoustic spectroscopy methods Comparison with the conventional cathode materials for lithium ion batteries this gap value is close to dd transition energy of Mn in LiMn2O4 163 eV or 200 eV and that of Co in LiCoO2 21 eV suggesting that Li5SiN3 is a possible cathode material The 5 × 5 mm2sized lithium secondary battery of Li5SiN3 cathode/propylene carbonate + LiClO4 electrolyte/Li anode structure shows a discharge capacity of 24 μAh cm−2 for a discharge current of 10 μA
Keywords: