Remote Plasma Atomic Layer Deposition of Thin Films of Electrochemically Active LiCoO2

One of the remaining challenges in the field of portable electronics is the miniaturization of lithium-ion batteries without decreasing their storage capacity. To tackle this challenge and to effectively integrate battery technology in even a wider variety of applications, it is essential to produce high quality thin films for all-solid-state batteries. A remote plasma ALD process for the positive electrode material LiCoO2 was developed using the combination of CoCp2 as the cobalt precursor, (LiOBu)-Bu-t as the lithium precursor and O-2 plasma as the oxidant source. The thin films were deposited at a temperature of 325 degrees C with a virtually linear growth rate of 0.06 nm/cycle. After annealing the samples at 700 degrees C for 6 minutes the high temperature phase LiCoO2 was obtained, as demonstrated by XRD and Raman spectroscopy measurements. Electrochemical charge/discharge cycling showed good electrochemical activity with a promising storage capacity.