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What causes a battery to self-discharge
234 2023-10-23
Battery self-discharge is a complex process involving many factors. In order to better understand this problem, this paper will conduct a detailed analysis from the chemical reaction, battery internal resistance, positive and negative active substances, impurities and moisture, and battery packaging and storage.
1. Chemical reaction
The main cause of battery self-discharge is the spontaneous chemical reaction within the battery. In a battery, there is an electrochemical reaction between the positive and negative electrode materials and the electrolyte, which creates an electric current in the external circuit. Inside the battery, however, these chemical reactions can also cause a loss of power.
For lithium metal batteries, self-discharge is mainly due to REDOX reactions. During the charging process, lithium ions escape from the positive electrode material and migrate to the negative electrode material. Over time, the lithium ions will react with the negative electrode material and become lithium metal again, resulting in a loss of electricity.
2, battery internal resistance
The internal resistance of the battery refers to the internal resistance of the battery, which has a certain impact on the self-discharge of the battery. The main sources of internal resistance include electrode materials, electrolytes, diaphragms, and defects in the manufacturing process.
The internal resistance causes the voltage inside the battery to drop, which affects the output performance of the battery. In addition, the internal resistance will increase the heat inside the battery, accelerate the deterioration rate of the battery, and then lead to the attenuation of the battery capacity. Therefore, reducing the internal resistance of the battery is an important means to improve the performance of the battery and reduce the self-discharge rate.
3, positive and negative active substances
Positive and negative active substances are important components of batteries, which are closely related to battery self-discharge. The positive electrode materials generally include transition metal oxides, fluorates, etc., while the negative electrode materials include graphite, hard carbon, etc.
The stability, particle size, density and other factors of positive and negative active substances will affect the self-discharge rate of the battery. For example, the instability of the active substance may cause it to decompose during storage, triggering self-discharge. In addition, the particle size and density of the active substance also affect the electrochemical performance and self-discharge rate of the battery.
4. Impurities and moisture
Impurities and moisture are also important factors affecting the self-discharge of batteries. In the battery manufacturing process, some impurities may be mixed, such as metal particles, oxides, and so on. These impurities will accelerate the deterioration process of the battery, resulting in an increase in the self-discharge rate.
In addition, moisture is also one of the important factors of battery self-discharge. The water in the battery will react with the positive and negative electrode materials, resulting in the attenuation of the battery capacity. Especially in the high temperature and high humidity environment, the influence of water on the self-discharge of the battery is more significant. Therefore, reducing the impurity and moisture content in the battery is an effective means to improve the battery performance and reduce the self-discharge rate.
5, battery packaging and storage
Battery packaging and storage methods also have an important impact on battery self-discharge. The battery package should be tight to prevent the entry of air and moisture. At the same time, the storage environment also needs to pay attention to, high temperature, high humidity, direct sunlight and other environments will accelerate the deterioration process of the battery, resulting in an increase in the self-discharge rate.
In order to reduce the self-discharge rate of the battery, the following storage measures can be taken: First, the appropriate packaging materials should be selected, such as aluminum foil film, good air permeability plastic bags, etc., to seal and moisture-proof, secondly, the battery should be stored in a cool and dry place to avoid direct sunlight and high temperature and high source environment; Finally, for long-term storage batteries, they should be regularly charged or replaced to maintain the activity of the battery.
In short, battery self-discharge is a complex process, which is affected by many factors. In order to reduce the self-discharge rate of the battery, it is necessary to comprehensively consider the chemical reaction, internal resistance of the battery, positive and negative active substances, impurities and moisture, and battery packaging and storage. By optimizing the battery structure and manufacturing process and selecting the appropriate storage method, the self-discharge rate of the battery can be reduced from the source, and the stability and service life of the battery can be improved.