Co3O4 as anode material for thin film micro-batteries prepared by remote plasma atomic layer deposition

Cobalt oxide thin films have been deposited with remote plasma atomic layer deposition (ALD) within a wide temperature window (100–400 °C), using CoCp2 as cobalt precursor and with a remote O2 plasma as oxidant source. The growth rate was relatively high at 0.05 nm per ALD-cycle and resulted in the deposition of high density (∼5.8 g cm−3), stoichiometric Co3O4. For the electrochemical analyses, Co3O4 was deposited on a Si substrate covered with an ALD-synthesized TiN layer to prevent Li diffusion. The as-deposited electrodes were investigated in a three-electrode electrochemical cell using constant current (CC) charge/discharge cycling and Galvanostatic Intermittent Titration Technique (GITT) in combination with Electrochemical Impedance Spectroscopy (EIS). Compared to the literature, ALD-deposited Co3O4 exhibited a high electrochemical activity (∼1000 mAh g−1) and the formation of a solid electrolyte interface has been identified by EIS.

► Preparation of cobalt oxide within a wide temperature window employing atomic layer deposition. ► Consistent material properties for deposition between 100 °C and 400 °C. ► Interesting anode material for application in all-solid-state microbatteries because of a high electrochemical activity. ► Extensive electrochemical investigation and evaluation of a conversion anode material (Co3O4) for application in microbatteries.