The present invention relates to a method and a device for operating a battery, in particular a lithium ion battery, in a consumer (load).
Rechargeable batteries, in particular lithium ion batteries, are used in a multiplicity of products as energy stores. Currently available lithium ion batteries are challenging from a safety point of view. In the event of an accident, the battery can burn, emit toxic gases and dusts and even explode. The thermal runaway in the case of lithium ion batteries is primarily due to the accelerated oxidation of an organic electrolyte (frequently organic carbonates, such as, e.g., ethyl carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), etc.) at high temperatures. The decisive factor here is the exothermal self-acceleration, which a battery undergoes up to the eventual fire and the thermal runaway associated therewith. The fire is ultimately triggered by the release of oxygen by the metal oxide cathode material, which together with the organic of the electrolyte produces a combustible mixture. LiCoO2 and LiNiO2 are known for such instabilities.
By means of more stable cathode materials, such as, e.g., the so-called NCM or respectively NMC (Ni—Co—Mn based), the release of oxygen can be shifted to higher temperatures and the danger of a fire is thus reduced. Besides the composite oxide NCM, the so-called NCA (Ni—Co—Al based) is also used. Batteries which are NCA based on the cathode side are often used for high performance applications, such as, e.g., E-bikes. NCA based batteries are, however, more challenging from a safety perspective in comparison to other batteries that are based on oxidic cathode material. The primary reason for this is due to the high nickel content, which as a NCA represents a comparatively instable structure and can release oxygen at elevated temperatures. Said oxygen reacts strongly with the organic electrolyte and leads to a so-called thermal runaway, which in turn can lead to a fire or an explosion.
In order to prevent this, there is a need for a safe and reliable management of such a battery.