Lithium Battery Safety: The Critical Dangers of Overcharging and Over-Discharging

In modern life, lithium batteries are widely used in many fields such as mobile phones, laptops and electric vehicles. With its advantages such as high energy density and long cycle life, it has become the preferred power source for many electronic products. However, overcharging and over-discharging will have a very serious impact on the safety of lithium batteries, and may even cause safety accidents and endanger our lives and property. So, what are the hazards of overcharging and over-discharging?

Overcharging refers to charging a lithium battery for too long, exceeding its normal charging capacity. During normal charging, the electrochemical reaction inside the battery is controllable, but the overcharge state will break this balance. As the overcharge progresses, the lithium ion concentration on the surface of the negative electrode is too high and begins to deposit to form lithium dendrites. These lithium dendrites are like sharp knives, cutting the inside of the battery wantonly. Once they pierce the diaphragm, they will cause a short circuit inside the battery. At the moment of short circuit, a large amount of heat is generated, and the battery temperature rises sharply, which may cause combustion or even explosion. In addition, overcharging will cause the electrolyte to decompose, produce gas, and increase the pressure inside the battery. When the pressure exceeds the limit of the battery shell, the battery will bulge or even rupture, and harmful substances will leak, polluting the environment and endangering human health.

Over-discharge should not be underestimated either. When a lithium battery is over-discharged and the discharge termination voltage is lower than the specified minimum voltage, the surface potential of the negative electrode drops sharply, triggering a series of adverse reactions. The organic solvent inside the battery begins to decompose, producing irreversible chemical changes, leading to a decline in battery performance, capacity decay, increased internal resistance and other problems. Moreover, the diaphragm will also be damaged, increasing the risk of internal short circuits. In low-temperature environments, over-discharge may also cause the electrolyte to freeze, further hindering ion transmission, and easily causing local overheating during subsequent charging, posing a threat to battery safety.

The safe use of lithium batteries is related to all aspects of our lives. In order to avoid the serious consequences of overcharging and over-discharging, we must take effective measures. In daily life, when charging the device, you should avoid long-term continuous charging. It is best to use the original or regular manufacturer's charger. These chargers are usually equipped with overcharge protection devices, which can automatically stop charging after the battery is fully charged. For devices with replaceable batteries, charge the battery in time when the battery power is 20% - 30% remaining to avoid excessive discharge of the battery. At the same time, check the battery status regularly. If abnormal conditions such as battery bulging and leakage are found, stop using it immediately and replace the battery. For large equipment such as electric vehicles, its battery management system (BMS) is crucial. It can monitor battery voltage, current, temperature and other parameters in real time, accurately control the charging and discharging process, prevent overcharging and over-discharging, and ensure the safe and stable operation of the battery.

In short, the impact of overcharge and over-discharge on the safety of lithium batteries cannot be ignored. Understanding these hazards and using lithium batteries correctly in daily life are important measures to ensure our safety. Let us start from now, cherish batteries, stay away from overcharge and over-discharge, and jointly create a safe power environment .