A LiCoO[sub 2] Cathode Modified by Plasma Chemical Vapor Deposition for Higher Voltage Performance

Surface modification of the electrode dramatically improved the performance of a electrode charged to 4.6 V. A diamond‐like carbon thin film was deposited uniformly on the electrode surface using dc plasma chemical vapor deposition. This surface treatment suppressed electrolyte decomposition during the charge process. When a coin‐type cell using this electrode was charged to 4.6 V, the discharge capacity in the first cycle was 212 mAh/g and the charge‐discharge efficiency was over 90% through five cycles. This treatment suggests a new approach to the development of cathodes for lithium‐ion secondary batteries. © 2000 The Electrochemical Society. All rights reserved.