Lithium-ion batteries convert chemical energy into electrical energy through normal chemical reactions. In theory, the reaction that occurs inside the battery is the oxidation-reduction reaction between the positive and negative electrodes. According to this reaction, the deintercalation of ions can generate current, so lithium The ion concentration usually does not change. However, in the actual battery cycle, in addition to the normal reaction of lithium ions, many side reactions will occur, such as the formation and growth of SEI film, and the decomposition of electrolyte. Any reaction that can produce or consume lithium ions will disrupt the internal balance of the battery. Once the balance is changed, it will have a serious impact on the battery. The internal factors of the battery that cause the decrease in the capacity and life of the lithium-ion battery are as follows: 1. The change of the positive electrode material. 2. The electrolyte is decomposed. 3. The formation and growth of SEI film. 4. The formation of lithium dendrites. 5. The influence of inactive ingredients.
The internal failure mechanism of lithium batteries is mostly caused by the formation of lithium dendrites, changes in the cathode material and the decomposition of the electrolyte. Among them, the formation of lithium dendrites can easily cause short circuits and cause thermal runaway of the battery cell. Cause the battery to explode.
In the final analysis, the failure research of lithium batteries is to study battery failure modes and mechanisms, optimize the battery, and improve battery safety. Therefore, battery failure research can not only have important guiding significance for actual production and operation, but also has vital significance for improving battery life, safety and reliability of electric vehicles, and reducing the cost of electric vehicles.
Post time: Nov-08-2021