Battery Internal Resistance affects on Lithium Battery
Description
Battery internal resistance refers to the resistance that current encounters when flowing through its interior during operation,it has multiple impacts on lithium batteries, as follows:
1.Affect the charging and discharging efficiency of the battery
1.1 Charging
It can cause the battery to heat up, and part of the electrical energy will be converted into heat energy and lost, reducing the charging efficiency,at the same time, due to heat generation, the chemical reaction rate inside the battery may accelerate, leading to overcharging during the charging process and affecting the battery’s service life.
1.2 Discharging
Internal resistance will cause the terminal voltage of the battery to drop and the output electrical energy to decrease,for instance, in some devices that require high power output, such as electric vehicles and power tools, if the internal resistance of the battery is relatively high, when discharging at a large current, the terminal voltage of the battery will drop rapidly, causing the device to be unable to obtain sufficient electrical energy and affecting its performance.
2.Affect the output power of the battery
According to the power formula (P = I*I*R) (where P represents power, I represents current, and R represents internal resistance), the greater the internal resistance, the greater the power consumed internally by the battery under the same current, and the smaller the power that can be output to the external load,this limits the use of lithium batteries in some application scenarios with high power requirements, such as unmanned aerial vehicles and high-performance electric vehicles.
3.Affect the service life of the battery
3.1 Accelerate battery aging
The heat generated by internal resistance will accelerate the decomposition of chemical substances inside the battery and the aging of electrode materials, gradually reducing the battery’s performance and shortening its cycle life,long-term use in high-temperature environments or high-current charging and discharging will cause the internal resistance to increase more rapidly, further shortening the battery’s service life.
3.2 It leads to battery imbalance
In a series lithium battery pack, due to the possible differences in internal resistance among individual cells, batteries with higher internal resistance will generate more heat during charging and discharging, causing their temperature to rise and further increasing their internal resistance,this imbalance phenomenon will intensify as the number of cycles increases, and eventually may lead to premature failure of some batteries, affecting the service life of the entire battery pack.
4.Affect the safety of the battery
4.1 Overheating risk
A relatively high internal resistance will generate a large amount of heat during charging and discharging,if the heat is not dissipated in time, it may cause the battery temperature to be too high, leading to thermal runaway and even safety accidents such as fire and explosion,especially in some high-temperature environments or when there is a short circuit inside the battery, the heat generated by the internal resistance may accumulate rapidly, increasing the safety risk.
4.2 Risks of overcharging and overdischarging
It will cause changes in the charging and discharging characteristics of the battery, increasing the risk of overcharging and overdischarging. overcharging can lead to problems such as increased internal pressure of the battery and decomposition of the electrolyte, while overdischarging may damage the electrode materials inside the battery. All these may affect the safety of the battery.
5.Conclusion
It has a wide-ranging and crucial impact on lithium batteries,it not only directly restricts the charging and discharging efficiency and output power of batteries, shortens their service life, but also brings significant safety hazards. In the research and development, production and use of lithium batteries, great attention should be paid to the internal resistance factor of the battery,through technological innovation and scientific management, the internal resistance should be reduced as much as possible to enhance the comprehensive performance and reliability of lithium batteries and ensure their safe and stable operation in various application scenarios.