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Are Batteries Safe?

In our daily lives, from mobile phones to laptops, from electric bicycles to new energy vehicles, the application of lithium batteries can be said to be pervasive. We cannot do without lithium batteries, and we are afraid of safety risks when using lithium batteries. Let’s find out how should we use lithium batteries correctly and ensure safety.

Why do we have to use lithium batteries?

Lithium batteries have become the preferred power source for electric vehicles and many other electrical appliances due to their high power density, lightweight, and environmental friendliness.

Why do lithium batteries catch fire/explode?

Lithium batteries mainly rely on the movement of lithium ions between the positive and negative electrodes to realize the charging and discharging process. From a principal point of view, the main factors causing lithium battery explosions are overcharge and short circuit.

Overcharging mainly occurs during the charging process of lithium batteries. Due to the resistance of the battery, the battery will accumulate a large amount of heat during the charging process. The protection device in lithium batteries can provide a certain degree of protection against overcharge by detecting voltage.

However, when the overcharge time is too long and the voltage continues to be too high, dendritic short circuits are likely to occur inside the lithium-ion battery, causing the temperature and pressure of the lithium battery to continue to rise, resulting in the risk of explosion and fire.

Short circuit mainly occurs during the use of lithium batteries. When the lithium battery is in use, its own temperature will continue to rise, and the battery will also maintain normal heat dissipation.

If the battery temperature is too high due to external factors, it will easily cause damage to the battery separator and cause a short circuit, which will cause excessive internal heat accumulation, trigger a chain chemical reaction, and cause the battery to explode and burn.

Therefore, some friends have said that lithium batteries are unsafe and it is better to replace lead-acid batteries in time. Is this true or false? Then read on…

Are lead-acid batteries safer?

Lead-acid batteries are used in electric vehicles, communication base stations and some portable devices.

Compared with lithium batteries, the management system of lead-acid batteries lacks overcharge protection for the battery during charging. Many chargers are also unable to cut off the power after full power. The probability of explosion when overcharged is higher than that of lithium batteries; and, The electrolyte of lead-acid batteries is highly corrosive sulfuric acid, which is more harmful than lithium batteries when leakage or explosion occurs.

Generally speaking, lead-acid batteries are not as safe as lithium batteries.

In daily life, you need to pay attention to avoid direct contact of lead-acid batteries with metal products to avoid corrosion. At the same time, avoid direct access of the battery to heat sources, which may cause excessive temperature and cause fire.

How dangerous is it to replace the battery without permission?

Changes in battery size can easily cause the internal battery to shake and affect its service life. Chargers for lithium batteries and lead-acid batteries are not universal, and there will be safety hazards when they are mixed for charging.

It is difficult to ensure that the battery connection is in full compliance with safety standards if it is modified privately, and there is a risk of short circuit or explosion during operation.

The general lifespan of an electric vehicle battery is 1 to 2 years. If the battery heats up severely during charging and has visible damage and deformation, such as a bulging battery or a damaged battery casing, it must be replaced at a professional maintenance point. In addition, “it’s full once it’s charged, and it’s empty once it runs away.” This is the most typical characteristic of battery vulcanization. At this time, the battery has failed and the battery needs to be replaced in time.

Instructions for using other batteries

1. Cell phone battery

When charging lithium batteries, you need to strictly abide by the charging time provided by the manufacturer. Terminate charging promptly when fully charged, and continuous charging should not exceed 8 hours. At the same time, do not charge in too high or too low-temperature environments, stay away from the bedroom when charging, and avoid flammable materials.

Try to choose original chargers and avoid using unqualified third-party chargers.

2. Alkaline battery

Alkaline batteries are mainly used in household equipment, such as watches, remote controls, toys, etc., which are what we often call “AA batteries” and “AA batteries”.

Alkaline batteries will “leak” when over-discharged. The alkaline solution is corrosive and will damage the equipment used.

Therefore, when using alkaline batteries, you need to pay attention to replacing low-power batteries in time. Never store batteries in the device for a long time, and avoid placing batteries in open flames to avoid explosions.

How to avoid accidents?

  1. Charge properly to avoid overcharging

When charging, plug in the battery plug first and then the power plug; when unplugging, pull out the power plug first and then the battery plug, taking care not to take too long.

2. Choose electric vehicles and battery products from regular manufacturers

Electric vehicles and battery products from regular manufacturers often undergo strict safety tests and are more secure.

Non-standard electric vehicles often have certain problems with the battery and circuit connections, which pose major safety risks during charging and use.

3. Never modify electric vehicles without permission

It is difficult to guarantee the quality of the original factory in the assembly process and cell selection of privately expanded batteries and batteries, which makes the battery prone to short circuit problems during use.

4. Use the original charger provided with your electric vehicle

Original chargers are often compatible with the battery’s charging protection function, but third-party chargers lack protection in this regard, which may cause battery damage and cause safety accidents.

5. Try to choose charging and parking locations with unified configurations

When charging and parking electric vehicles, try to choose a location with uniform configuration and high security. Do not charge or park electric vehicles in public areas such as corridors and public foyers.

6. Avoid exposing the battery to direct sunlight

Excessive external temperature can easily affect the heat dissipation of the lithium battery itself, causing the internal temperature of the battery to be too high, causing diaphragm meltdown and short circuits.

Therefore, the battery should be kept away from direct exposure to the sun and away from heat sources that are too hot.

To sum up, in daily life, we must pay attention to the correct use of batteries. Do not replace the batteries of electric vehicles without permission. Try to place them in uniformly configured parking places. Remember not to place them in corridors or public foyers. When taking public transportation, you must also abide by the regulations and do not carry excessive or substandard batteries.

Author丨Chu Yuhao, Ph.D. of Beijing University of Chemical Technology, engineer of Sinopec Beijing Research Institute of Chemical Industry

Review丨Li ​​Quan, Ph.D., Institute of Physics, Chinese Academy of Sciences

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