Reasons for the reduced capacity of lithium-ion batteries

The capacity of lithium-ion batteries will decrease after a certain number of cycles. What is the reason for the decrease in capacity of lithium-ion batteries?

The capacity of lithium-ion batteries will decrease after a certain number of cycles, and the internal resistance will increase at the same time. What's causing this? What are the reasons for the reduction in the capacity of lithium-ion batteries?

lithium-ion battery

1. Cell aging and decay.

2. The self-discharge rate is different, resulting in an unbalanced charge of the series cells, which eventually leads to a reduction in the capacity of the lithium-ion battery and is not durable.

3. During the use and charging and discharging of lithium-ion batteries, vulcanization will occur and affect the battery capacity. The vulcanization of the battery is as follows: the voltage of the battery itself is low, it will be full after charging for a while, and it will be gone after discharging for a while. The softening of the battery is manifested as the liquid inside the battery is cloudy and black. The battery capacity is reduced, and the lead powder falls off over time and for a long time.

4. Improper charging in summer and winter. The charging voltage of the battery is inversely proportional to the ambient temperature, so the temperature in summer is high, and the overcharge of the lithium-ion battery causes the battery to lose water, resulting in the battery bulging and deforming. In winter, the mileage will decrease due to insufficient charging.

5. Each charge and discharge will make a part of the lithium ions coat the surface of the negative electrode, which hinders the insertion of normal lithium ions. After many cycles, more and more are accumulated. Capacity began to show a noticeable drop.

6. The metal lithium formed between the negative electrode and the separator will block the pores of the separator and increase the internal resistance of the battery.

7. The inert substances in the electrochemical reaction inside the lithium-ion battery will destroy the capacity balance between the electrodes, resulting in capacity loss. This loss is usually irreversible.

8. Electrode instability. The positive electrode active material will oxidatively decompose the electrolyte in the charged state, resulting in capacity loss.

There are two common repair methods for lithium-ion battery capacity decline: freezing method and overcharge and over-discharge method.

1. Freezing

Wrap the lithium-ion battery of the old mobile phone that is used for automatic shutdown with plastic wrap, and try to be docile when wrapping it. There are three layers inside and outside to ensure that the lithium-ion battery is in a vacuum state. Then, wrap three layers of newspaper on the outside of the plastic wrap to completely seal the lithium-ion battery. Put it in the freezing layer of the refrigerator. After 48 hours, take out the lithium-ion battery and remove the six layers of paper film wrapped around it. The surface of the lithium-ion battery does not expand or deform due to freezing. After cooling for a while, then recharge.

2. Overcharge method

Fully discharge Li-Ion batteries that are nearing end-of-life, then recharge them to activate them. The specific method is the deep discharge of the mobile phone, which is to achieve a deeper level of recharging by exhausting the internal power, which requires some unconventional methods. Connect the phone to a small low-voltage light bulb with a special device, and the power inside the battery is transferred to the small light bulb until it all glows. Cell phones drain power slowly through lower voltages. Under normal circumstances, if the mobile phone is connected to a voltage lower than the rated voltage of 3.6 volts, it will automatically shut down. After discharge, a recharged phone battery can last longer.

The above is the reason for the reduction of the capacity of lithium-ion batteries, I hope to help everyone. If you are interested in lithium-ion batteries, welcome to pay attention to our website.



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