Review - multiscale characterization of Li-Ion batteries through the combined use of atomic force microscopy and X-ray microscopy and considerations for a correlative analysis of the reviewed data

The present review analyses the recent literature on the combined use of X-ray microscopy (XRM) and atomic force microscopy (AFM) for the multiscale characterization of Li+ (or Li) batteries (LiBs) with the aim of developing guidelines for their correlative analysis. The usefulness of XRM resides in the capability of affording non invasively in situ images of the inner parts of a LiB (an encapsulated device) with spatial resolution of dozens of nm during LiB operation. XRM is non destructive and affords the early diagnosis of LiBs degradation causes when these manifest themselves as microdeformations. The multiscale characterization of LiBs also requires AFM for visualizing the morphological/physical alterations of LiB components (anodes, cathodes, electrolyte) at the sub-nanometer level. Different to XRM, AFM necessitates of a modification of LiB working configuration since AFM uses a contacting probe whereas XRM exploits radiation-matter interactions and does not require the dissection of a LiB. A description of the working principles of the two techniques is provided to evidence which technical aspects have to be considered for achieving a meaningful correlative analysis of LiBs. In delineating new perspectives for the analysis of LiBs we will consider additional complementary techniques. Among various AFM-based techniques particular emphasis is given to electrochemical AFM (EC-AFM).