Li-Batteries electrode characterization: from conventional to phase contrast and spatial resolution

HELEN GOITIA; J. SILVEIRA; GIOVANETTI L. J.; F G. REQUEJO

Antofasta

Congreso; 7ma versión de la Conferencia Internacional de Litio, Minerales Industriales y Energía; 2020

CELiMIN

Lithium-ion batteries (LIBs) studies look to optimize interface processes of the reversible ion uptake and limit the material deterioration during the cycles. In the pursuit of higher-energy-density LIBs, one major challenge is the stability of high-capacity and high-voltage cathodes with electrolytes. Cathode materials based on Mn spinels LMNO are promising candidates because they are safer, cheaper and possess higher energy densities compared with the state-of-the art LiCoO2 (LCO)[1]. Using DXAS beamline at the recently closed LNLS, we were able to follow changes in the electronic structure in operando conditions by X-ray absorption Near Edge Structure of LMNO modified with Ni and Ti at Ni and Mn K edges (these results are shown in the poster # presented by Giovanetti et al.). Those characterizations gave relevant information that could be improved by increasing the spatial resolution scale or taking advantage of the phase contrast capability that will be available in the new 4th generation machine (Sirius). As an example spatially correlated X-ray pictographic tomography, known as X-ray ptychography[2,3], is a lensless imaging technique that provides quantitative electron density tomograms of the extended system at levels of spatial resolution hardly achievable by common X-ray microscopic techniques. Through this phase contrast based techniques and, for example, scanning X-ray diffraction microscopy[4], it is possible to directly visualize morphological and crystalline changes. This information would enable the stresses in crystals, within individual secondary particles, that is only possible with a few nm resolutions. These tools also allow the study with chemical selectivity and in hierarchical structural levels, with spatial resolution and under real operating conditions of the batteries. In this work we describe the state of the art of these novel experimental methodologies, that could be implemented in Sirius, with the possibility of the characterization of electrodes used in Li+ ion batteries in operando conditions.