Nickel-cobalt oxide thin-films anodes for lithium-ion batteries

Abstract

Thin-film transition metal oxides can be applied as transparent conductive coatings, photocatalysts, thermoelectric generators, and battery electrodes. In power sources application binary transition metal oxides are attractive due to high theoretical capacities. Among them nickel-cobalt oxides possess the highest (NiCoO2, 717mAh/g or 471.4 μAh cm-2 μm-1). This work is devoted to Atomic layer deposition (ALD) of thinfilms of nickel-cobalt oxides and evaluating their performance as negative electrodes for solid-state lithium-ion batteries. Ni-Co-O thin films were synthesized with different NiO/CoO ALD cycles ratio (5/1, 3/1, and 1/1) using nickelocene, cobaltocene and oxygen plasma. Both NiO and CoO crystal phases were observed in deposited films. The content of chemical elements (C, O, Ni and Co) in the film's depth are uniform, except for sample 5/1. The electrochemical performance of synthesized thin films was studied by cyclic voltammetry and galvanostatic cycling. It was found that with an increase of the nickel content in the coatings, the electrode's specific capacity is increasing. The highest capacity at high discharge currents (35C) is observed for the sample obtained with NiO/CoO - 5/1 ratio (660 μA·h·μm-1·cm-2)