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July, 2022

Operando electrochemical transmission electron microscopy (ec-TEM) promises high resolution (spatial and temporal) imaging of electrochemical systems, such as batteries, as they operate inside of a microscope. Such experiments are challenging in many ways but could provide new insights into the nanoscale principles of operation and degradation of societally important systems. Here, we investigate the possibility of using aerosol jet printing as a way of depositing Li-ion battery cathode and anode materials on special chips for ec-TEM. By using aerosol jet printing, we could place small features (line width <30 µm) with high accuracies as well as control the coverage and shape of the deposits. A welcome side-effect of the way aerosol jet printing works is that it selectively prints small particles, which is valued for TEM studies, where thin samples offer better resolution. We verified that the printed materials behave electrochemically similar to traditionally prepared batteries. In summary, aerosol jet printing approach is a very versatile and robust way of preparing microbatteries for ec-TEM studies and this study is an important step towards more straightforward and reliable ec-TEM studies. Future work based on this study will ultimately provide novel insights on the working and degradation principles of modern battery systems.

Figure: (a-d) SEM images of printed LiNi0.8Mn0.1Co0.1O2 (NMC811) with or without conductive carbon additive on ec-TEM chip working electrode. Scale bars are 10 µm for (a, c) and 2 µm for (b, d). (e) SEM image of fully printed ec-TEM chip containing the anode material (lithium titanate) on the outer circular counter electrode and NMC811 on an inner working electrode that is placed over an electron-transparent window. Scale bar 200 µm and 20 µm for the inset. (f) particle size distributions of printed NMC811 and just sonicated NMC811, which shows size-selectivity of the printing process. (g) TEM image of the printed samples showing small crystals of NMC811 in contact with the working electrode. Scale bar 200 nm.

J.K. Morzy, A. Sartor, W.M. Dose, C. Ou, S. Kar-Narayan, M.F.L. De Volder, and C. Ducati, "Aerosol Jet Printing as a Versatile Sample Preparation Method for Operando Electrochemical TEM Microdevices", Adv. Mater. Interfaces 2022, 9, 2200530