Electrodes: definitions and systematisation – a crystallographers view

Electrodes are, in combination with electrolytes and the active, reacting materials the function-giving materials in electrochemical energy storage devices. They are responsible for the transfer of electrons and provide the surface at which the electrochemical reactions take place. Those electrochemical reactions span the potential difference which drives the battery. We present a crystallographically inspired systematisation of all electrodes found in electrochemical storages that comprise inert and reactive electrodes, subdivided in active and passive electrodes, and solvation, mixed crystal, and phase transition electrodes, respectively. After the description of all electrode types we present a concise summary of battery chemistries and the applied electrode types.