In Situ Liquid Electrochemical TEM Investigation of LiMn1.5Ni0.5O4 Thin Film Cathode for Micro‐Battery Applications. Issue 2 (26th December 2021)

• Record Type: Journal Article
• Authors: Bhatia, Ankush; Cretu, Sorina; Hallot, Maxime; Folastre, Nicolas; Berthe, Maxime; Troadec, David; Roussel, Pascal; Pereira‐Ramos, Jean‐Pierre; Baddour‐Hadjean, Rita; Lethien, Christophe; Demortière, Arnaud
• Is Part Of: Small methods. Volume 6:Issue 2(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-26
• Subjects: 4D STEM ASTAR -- focused ion beam lamella connection to micro‐chip -- in situ liquid electrochemical transmission electron microscopy -- LiMn 1.5Ni 0.5O 4 cathode materials -- thin film microbatteries; Nanotechnology -- Methodology -- Periodicals; Nanotechnology -- Periodicals; Periodicals; 620.5028
• DOI: 10.1002/smtd.202100891
• Languages: English
• ISSNs: 2366-9608

Abstract

Abstract: Micro‐batteries are attractive miniaturized energy devices for new Internet of Things applications, but the lack of understanding of their degradation process during cycling hinders improving their performance. Here focused ion beam (FIB)‐lamella from LiMn1.5 Ni0.5 O4 (LMNO) thin‐film cathode is in situ cycled in a liquid electrolyte inside an electrochemical transmission electron microscope (TEM) holder to analyze structural and morphology changes upon (de)lithiation processes. A high‐quality electrical connection between the platinum (Pt) current collector of FIB‐lamella and the microchip's Pt working electrode is established, as confirmed by local two‐probe conductivity measurements. In situ cyclic voltammetry (CV) experiments show two redox activities at 4.41 and 4.58/4.54 V corresponding to the Ni 2+/3+ and Ni 3+/4+ couples, respectively. (S)TEM investigations of the cycled thin‐film reveal formation of voids and cracks, loss of contact with current collector, and presence of organic decomposition products. The 4D STEM ASTAR technique highlights the emergence of an amorphization process and a decrease in average grain size from 20 to 10 nm in the in situ cycled electrode. The present findings, obtained for the first time through the liquid electrochemical TEM study, provide several insights explaining the capacity fade of the LMNO thin‐film cathode typically observed upon cycling in a conventional liquid electrolyte. Abstract : In situ cycling of a LiMn1.5 Ni0.5 O4 (LMNO) thin film cathode in an electrochemical transmission electron microscope (TEM) holder reveals structural and morphologic changes upon (de)lithiation processes. (S)TEM images of the cycled thin film reveals formation of voids, cracks and organic decomposition products. The 4D STEM ASTAR technique highlights the emergence of an amorphization process in the in situ cycled electrode.