Three 300 cycle system tests with different charge discharge times were carried out with Sony 18650 rechargeable battery. The results show that the attenuation coefficient of battery power, the reduction of battery power, the expansion of battery internal resistance, the expansion of battery internal resistance, the expansion of battery internal resistance and the expansion of battery internal resistance; In addition, the charge and discharge of polymer cell will cause a large amount of heat in the rechargeable battery and accelerate the embrittlement of rechargeable battery. According to the observation of transmission electron microscope, it is found that the SEI film on the surface of charge and discharge level of polymer cell rechargeable battery is lower than that of charge and discharge.

3. The harm of deep discharge to the SOH value of rechargeable battery

The deep charging layer of the battery is related to the physical and mental health and embrittlement of the battery. I have the opinion that the battery has accumulated total migration energy. According to the total migration energy, I analyze the volume attenuation coefficient and embrittlement of the battery. According to the experiments on the circulation system in different deep layers of charge and discharge of lithium batteries, Fei et al analyzed the relationship between the accumulated migration kinetic energy of batteries and the attenuation coefficient of battery capacity. It was obtained that the accumulated migration energy of batteries under deep charge and deep discharge and shallow discharge were basically the same before the attenuation coefficient of battery capacity reached 85%. When the attenuation coefficient of battery capacity reached 85% ~ 75%, The accumulation and migration kinetic energy and kinetic energy efficiency of the battery under the deep charge and deep discharge method are better than those under the shallow discharge method.

4. Harm of distance between circulating systems to SOH concentration value of rechargeable battery

The interval time of the cycle system of charge and discharge lithium battery pack will also endanger the whole process of the embrittlement of the rechargeable battery. The interval time of the cycle system is different, and the internal resistance of the matched battery is different. Therefore, the scalding and reflection of the rechargeable battery during the cycle system period are slightly different, and the long-term operation will endanger the physical and mental health and embrittlement of the rechargeable battery. Experts believe that the SOC of rechargeable battery is 20% ~ 80%, which is beneficial to the physical and mental health of rechargeable battery and the service life of circulating system.

5. Harm of battery charging cut-off voltage to SOH value

Overcharge and power loss of lithium battery pack will endanger the physical and mental health of rechargeable battery, and poor working voltage upper and lower limits will also endanger the physical and mental health of lithium battery pack. With the decrease of the working voltage up to charge and discharge, the internal resistance of the battery expands, resulting in the internal scalding of the battery. In addition, it increases the adverse reactions, reduces the active substances of the battery, collapses the negative high-purity graphite sheet, accelerates the embrittlement of the battery, and reduces the volume of the attenuation coefficient. Excessive battery charging cut-off voltage will expand the internal resistance of the battery and increase the internal scalding of the charging battery. Excessive battery charging will cause negative level and “lithium precipitation”, which will increase adverse reactions and endanger the battery power and embrittlement.

In a word, the operating temperature of rechargeable battery, battery charging rate, deep charge and discharge, time interval of circulating system and battery charging cut-off voltage will endanger the physical and mental health and service life of rechargeable battery. The scientific research on the influencing factors of battery health is still in the link of qualitative analysis at this stage. The qualitative analysis of influencing factors and the coupling relationship between each element are not only a difficult problem in scientific research, but also a network hotspot in the scientific research of battery health and service life in the future.