In situ morphological studies of lithium electrodes by atomic force microscopy (AFM)

This work demonstrates the applicability of in situ atomic force microscopy for the study of the highly sensitive lithium electrodes in Li battery electrolyte solutions. A special working station was constructed in which the AFM system is located in a vibration-protected glove box and thus, all the measurements are performed under highly pure argon atmosphere. It was demonstrated that in spite of the fact that the measurements are carried out in the so-called contact mode, there are no detrimental interactions between the tip and the electrode surfaces. Repeated scans of the same areas did not result in any change in the imaged electrode topography, and thus the measurements are reliable. In this study, Li electrodes were imaged in a variety of important Li battery electrolyte solutions as a function of immersion, cathodic and anodic processes. The effect of the solvent, salt and additives on the Li electrodes' morphology was studied. The solvents included alkyl carbonates such as propylene, ethylene and dimethyl carbonate, and the salts included LiAsF6 and LiPF6. The effect of the presence of water and CO2 was also studied. A pronounced effect of the solution composition on the Li electrodes' morphology is demonstrated.