Publication

Abstract : Conversion materials with high specific capacity are of interest to improve energy density of Li-ion batteries. Here, we present results concerning hydrothermally synthesized CuO nanoplates that exhibit high specific capacity of 800 and 698 mAh/g at C/2 and 1C rates respectively and 180 mAh/g at a high rate of 30C. The electrodes exhibit high Coulombic efficiencies of about 66% and 60% at C/2 and 1C rate respectively, these are high efficiency values compared to the ones reported in the literature at respective rates. To understand the high performance, ex situ x-ray diffraction at different states of first discharge/charge is utilized that shine light on the lithiation/delithiation pathways of the CuO nanoplates. Lithiation proceeds through multiple phase transition CuO → Cu4O3 → Cu2O → Cu and it was found that Cu4O3 is reversible at the end of first charge. Cu and residual Cu2O was observed at the end of lithiation along with Li2O and Li2O2 phases. At the end of first charge, Cu4O3 phase along with CuO was observed as a major end-product with relatively minor concentrations of Cu2O. Cu4O3 as a major constituent observed in composite electrode seems to be the key information that can explain good reversibility and high Coulombic efficiency reported in the present work. © 2017 Wiley-VCH Verlag GmbH amp; Co. KGaA, Weinheim