Structural and electrochemical kinetics of Na-Fe-Mn-O thin-film cathode: a synergistic effect of deposition conditions

Thin films of Na-Fe-Mn-O (NFMO) are deposited on stainless steel, silicon, and Pt/Si substrate by pulsed-laser-deposition technique. Deposition done on silicon substrates are used for morphological studies. The present work establishes a co-relation among deposition temperature on morphology and electronic state, followed by its effect on electrochemical properties of NFMO thin films. Deposition on stainless steel at 600 degrees C favors a higher Fe3+/Fe4+ ratio of 1.05 and a lower Mn2+/Mn3+ ratio of 0.49 in the deposited film. This gives rise to a wide redox reaction couple of transition metal (Mn3+/Mn4+ and Fe3+/Fe4+). The NFMO thin-film cathodes offer a high capacity of 125 mAh g(-1) at 0.7 C (approximate to 182 mA g(-1)) for stainless steel substrate deposited at 600 degrees C. Cyclic voltammetry of the thin films on stainless steel substrate reveals polarization as a function of deposition temperatures. With further analysis of cyclic voltammetry, it seems likely that the extra pseudocapacitive charge storage promotes the high-capacity without leading to any structural change.

Automated summary

The study investigates the deposition of NFMO thin films on various substrates using pulsed-laser-deposition technique and explores the influence of deposition temperature on the morphology, electronic state, and electrochemical properties of the films. NFMO thin films deposited on stainless steel substrates exhibit high energy storage performance under different deposition conditions.