Solid electrolyte batteries are based on the principle of solid electrolyte fuel cells which are expanded by addition of storage elements to the battery.  These storage elements usually comprise ceramic main elements in which particles of a metal and/or a metal oxide which together form a redox pair are embedded.  In the charged state of the battery, the particles are reduced to the metal.  Energy can be obtained by means of atmospheric oxygen and be taken off as electric energy at the tapping poles of the batteries.  When the metal particles are completely oxidized to the respective metal oxide, the battery is discharged.  In order to recharge the battery, the fuel cell is then operated in the electrolysis mode, forming hydrogen which reduces the metal oxides back to the metal. 
The discharging process, i.e. the oxidation of the metal particles into solid, is based predominantly on cationic diffusion.  During the discharging process, there is therefore gradual migration of the metal of the metal particles in the direction of the oxygen source, since diffusion of the metal species occurs preferentially over the diffusion of the oxygen species.  This leads to a continuous degradation of the storage structure and thus to a gradual change in the charging and discharging characteristics, to an increase in the charging and discharging times required and also to a decrease in the useful capacity. 
Furthermore, the cationic diffusion leads to nonoptimal reaction kinetics of the redox process, since oxygen transport is inhibited in the center of the storage particles or layers.