Method for determining the state of charge of an electrochemical cell

摘要

The conductivity or the electrical resistance R of the active material of an electrode changes with the conversion level of the reaction supplying the current. If the specific conductivities of the active material and of the metallic framework substance are not too different from one another, this also applies to the electrode as an entity. A new method uses the said relationship to determine the charge state of a battery, in that a high-frequency alternating current I AC is passed through the electrode (1) in situ via the connections (2) (tab) and (4), and the resultant AC voltage U AC is picked off between the points (3) and (5). If the rms value of I AC is constant, said AC voltage U AC changes in direct proportion to R and represents a measure of the actual charge state. The charge state can be read off by means of an analog or digital display (for example in %) on a display unit which is part of the measurement arrangement.