The contribution emphasizes the central role of point defect chemistry for battery materials. While the significance for solid electrolytes is well appreciated, there are only a few examples, where defect chemistry is taken seriously for electrode materials. This is astonishing as it is only defect chemistry which allows for a proper understanding of both equilibrium (e.g. theoretical capacity, cell voltage) and non-equilibrium properties (losses due to transport problems, charge-transfer resistance, concentration polarization). Furthermore defect chemistry provides the framework for both a materials analysis and a materials search. Selected examples are discussed which refer to various storage modes, corroborating this statement (FePO4, Li2O2, TiO2, Ru : Li2O). (C) 2015 The Electrochemical Society. All rights reserved