Scanning electron microscopy and electron energy loss spectroscopy (STEM/EELS) offers unprecedented spatial resolution, which has enabled nanoscale imaging and chemical analysis of battery materials - their surfaces, grain boundaries and phase boundaries. Combining the state-of-the-art in situ operando analytical electron microscopy with first principles (FP) computational data analysis, we reveal some insights that could not be possible to see in the past.  On the other hand coherent x-ray diffractive imaging (CXDI), a lensless form of microscopy capable of discerning electron density and strain with 20 nm resolution, can be used to map the strain evolution of a single cathode particle in a functional battery material as it is cycled in-situ. The evolution of compressive/tensile strain reveals a number of interesting phenomena. For instance, strain can be quantitatively correlated to the Lithium amount in the initial cycles, eventually becoming uncorrelated upon long-term cycling. We demonstrate that CXDI is a powerful diagnostic tool to reveal correlation between strain and electrochemistry at the single particle level and offers valuable information for electrode/battery modeling and future battery design. By combining electron based and X-ray based novel imaging techniques, we showcase the state-of-the-art diagnostic tools developed for probing functional battery materials in operando.