As a Lithium Battery Scooter Factory, share with you. The secondary
batteries have self-discharge phenomenon, the voltage is relatively high and the
self-discharge rate is relatively low, which is a selling point of lithium
batteries. What is self-discharge? A battery that initially has a certain amount
of power will be left open for a period of time under the specified environment,
and some of the power will be lost due to various reasons. The ability of the
battery to keep exhausted or a lot of power is not lost is the ability of the
battery to charge, and the ratio of the remaining power to the original power is
the self-discharge rate.
1 Innate factors affecting self-discharge rate
Why does a battery placed in an open circuit lose charge? The innate influence mainly comes from the loss of electrochemical data inside the battery and the internal short circuit of the cell. The loss of cell data is an irreversible response, which results in the loss of cell capacity. How much is lost is the performance of capacity recovery performance; the power loss caused by the short circuit consumes the current power and the capacity is not affected by this part of the response.
The sum of the power loss caused by the capacity loss and the simple power loss is the self-discharge amount.
1.1 Side effects of electrochemical data
The secondary response of data mainly occurs in three parts, positive data, negative data and electrolyte.
The positive data are mainly all kinds of lithium compounds, and there is always a small amount of reverberation with the electrolyte. The environmental conditions are different and the intensity of the reverberation is also different. The positive electrode material and the reaction of the electrolyte generate an insoluble product, making the reaction irreversible. The positive data that participated in the response lost its original structure, and the battery lost its corresponding power and permanent capacity.
The negative electrode data, graphite negative electrode has the ability to react with the electrolyte. During the formation process, the reaction product SEI film is attached to the surface of the electrode, so that the electrode and the electrolyte have stopped the intense reaction. However, through the shortcomings of SEI membrane, this response has been carried out in a small amount. The reaction of the electrolyte and the negative electrode consumes the lithium ions in the electrolyte and the negative electrode data together. The reaction brings along with the loss of power, and also the loss of the maximum available capacity of the battery.
1.2 Internal short circuit
In the production process of the battery, some dust impurities are inevitably mixed in. These impurities have messy characteristics. Some impurities can form a slight conduction between the positive and negative electrodes, which neutralizes the charge and damages the power.
Collector size errors and processing burrs may also lead to positive and negative electrodes. At the beginning of the life of the battery cell, it only shows that the self-discharge is higher, and the longer the time, the greater the possibility of forming a large-scale short circuit of the positive and negative electrodes, which is an important cause of battery thermal runaway.
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