Electrochemical behavior of carbon-coated silicon monoxide electrode with chromium coating in rechargeable lithium cell

The effects of Cr coating are studied with respect to improving the electrochemical characteristics of carbon-coated silicon monoxide anodes in rechargeable Li cells. The Cr coating is applied by ion beam sputtering. Analyses of the coating are carried out by EDX, SEM, TEM, and EPMA. A coin cell (CR2032) with a carbon-coated SiOx anode coated with Cr and a lithium cobalt oxide (LCO) cathode is assembled in an argon-filled glove box. The charged capacity of the Cr-coated SiOx–C/LCO cell is 1127 mAh g−1 in the 1st cycle at 0.1 C, while that of the uncoated SiOx–C/LCO cell is 956 mAh g−1. In addition, the Cr-coated SiOx–C/LCO cell has a discharged capacity of 733 mAh g−1, which is higher than that of the uncoated cell (635 mAh g−1). Furthermore, the discharge capacity retention ratio (100th:2nd) of the Cr-coated cell is 75% while that of the uncoated cell is 69%. The rate capability of the Cr-coated cell is superior to that of the uncoated cell. Cr has good electrical conductivity, enabling more Li ions to be stored in the Cr-coated cell than in the uncoated cell. Investigations into the improved electrochemical characteristics are carried out through the analyses of impedance, voltage profile, and cycle data.

► Chromium is coated unto the silicon monoxide carbon composite electrode through ion beam sputter. ► Capacity of the coated cell was 1127 mAh g−1 at the first while that of the uncoated cell is 956 mAh g−1. ► The capacity retention ratio of the Cr-coated cell is 75% while that of the uncoated cell is 69%. ► The Cr has good electrical conductivity, strong adhesion to the substrate and high hardness.