A detailed analysis of the causes of battery failure in soft-pack battery equipment ?

Lithium-ion battery failure performance and failure mechanism

(1) Capacity attenuation: The capacity attenuation of ion batteries is mainly divided into two types: reversible capacity attenuation and irreversible capacity attenuation. Reversible capacity attenuation can recover the lost capacity by adjusting the battery charging and discharging system and improving the battery usage environment. Irreversible capacity attenuation is the irreversible change in the battery's internal capacity that produces irreversible capacity loss.The origin of battery capacity decay failure lies in the failure of data, and it is closely related to objective factors such as battery manufacturing process and battery use environment. From a data point of view, the main causes of failure are the structural failure of the positive electrode material, the transitional growth of SEI on the negative electrode surface, the decomposition and transformation of the electrolyte, the corrosion of the current collector, and the trace impurities of the system.

(2) Increase in internal resistance: The internal resistance of a lithium-ion battery is related to the process of electron transmission and ion transmission within the battery system. It is mainly divided into ohmic resistance and polarized internal resistance, during which the polarized internal resistance is mainly caused by electrochemical polarization. There are two kinds of electrochemical polarization and concentration polarization. The primary factors that lead to the increase of the internal resistance of lithium-ion batteries are divided into battery key information and battery use environment. Que Yongchun of the University of Science and Technology of China used synchrotron radiation technology to propose that the jump mechanism of transition elements is the cause of potential hysteresis and voltage attenuation: It explains that within the battery system, the abnormality of key data is the fundamental factor affecting the increase of internal resistance and battery polarization.

(3) Internal short circuit: The performance of short circuit can be divided into: ① short circuit between copper/aluminum current collectors; ② diaphragm failure loses electronic insulation or open ground becomes micro-contact between positive and negative electrodes, showing some serious heating, and then further charging and discharging In the process, it may diffuse to the surroundings and cause thermal runaway; ③The positive electrode slurry guesses that the transition metal impurities are not removed cleanly, piercing the diaphragm, or promoting the formation of negative electrode lithium dendrites, causing internal short ircuits; 

④Lithium dendrites cause internal short circuits. In addition, in the process of battery planning and manufacturing or battery pack assembly, unreasonable planning and partial pressure can also cause internal short circuits.