The focus of my research is the in-depth understanding of complex mechanisms and processes that occur in electrode materials of diverse battery chemistries during their operation. For this I employ different material characterization techniques under in situ conditions to study the morphological, micro-, electronic- and crystal-structural changes occurring during electrochemical cycling. Paired with post mortem analysis and theoretical calculations I use these insights to reconstruct a complete picture of the reversible and irreversible electrochemical reactions that determine battery performance.