The lithium-ion battery generates heat after the first formation after charging. Battery charging and discharging efficiency is low. Battery voltage drops rapidly and continuously. the battery is dissected, it is found that there is a space corresponding to the battery compartment There are many black spots on the surface of the negative electrode, and the negative electrode plate corresponding to the black dots shows traces of. combustion and removal of powder.
The components of the black spots were determined by scanning electron microscopy energy spectrum analysis of the diaphragm black spots. From the energy spectrum data, it was known that the main components of black spots. black spots are carbon and fluoride and a small amount of iron. At the same time, there was a die leakage phenomenon at thenegative electrode corresponding to the black dots, which determined that the black dots were formed by the carbon negative electrode material. stuck to the surface of the separator.
Through microscopic observation, the black dots on the separator are essentially in the shape of round dots. The negative carbon electrode on the blackboard falls off easily, and the dark matter remains in the board. separation spots after fall. An energy spectrum scan was performed on the negative electrode surface and the positive electrode surface corresponding to the black dots on the separator. Scanning electron microscopy revealed that some of the separator micropores at the separator black spots had been closed. , it is known that the negative carbon electrode is bonded to the separator due to high local surface temperatures. ?
The energy spectrum analysis data showsNote that there is a small amount of iron ions on the blackheads after the battery is fully charged. charged, the positive and negative electrodes will expand due to the expansion of the plates. The distance between the plates will decrease due to thelithium iron phosphate microparticlespresent between the battery plates. >forming a polarization discharge and generating high temperature, the separator will partially close the poresThe negative electrode falls and is stuck to the surface of the separator.