Once again, it’s “one bar”! Why do mobile phone batteries become less durable as they are used? | Digital Literacy

Audit expert: Zhou Hongzhi

Senior Experimenter and Master Supervisor at the School of Physics and Optoelectronic Engineering, Beijing University of Technology

Nowadays, mobile phones have become an indispensable part of our daily lives. Many people will find that as the use time increases, the battery of the mobile phone seems to be less and less durable, and the usage time after each full charge is getting shorter and shorter. This phenomenon has aroused widespread concern and discussion. Why are mobile phone batteries becoming less and less durable?

Lithium battery life decay mechanism

At present, most mobile phones on the market use lithium-ion batteries, which have the advantages of large capacity, small size, high voltage platform and long cycle life.

In fact, any chemical energy storage battery has a decay process. In layman's terms, the energy of a battery can be understood by the concept of " the number of active electrons ". The more active electrons there are, the higher the battery energy is, and vice versa, the lower the power is. This is also known as capacity.

The charging and discharging of the battery is to replenish and consume these active electrons. When the battery is used, the active electrons flow from the cathode to the anode through the external load to do work, such as the use of a mobile phone. At this time, the load consumes the active electrons, reducing the active electrons inside the battery. When charging, the charger replenishes the active electrons to the battery cathode, restores the number of active electrons in the battery, and thus restores the battery's energy.

It should be noted that the number of active electrons will gradually decrease in this repeated process . The reasons for this decrease include aging of the battery poles, oxidation and degeneration of the cathode, aging and deterioration of the chemical medium, etc. These changes are due to the characteristics of the metal electrodes themselves, as well as damage caused by improper use. Of course, lithium batteries also follow this rule.

Therefore, the life of lithium-ion batteries is limited, and their performance will gradually decline as the use time increases. This life decay is mainly affected by the following factors:

Battery cycle number : A battery cycle refers to the process of discharging the battery from a fully charged state to an empty state below 25%, and then charging it to a fully charged state above 90%. As the number of cycles increases, changes inside the battery cause the battery capacity to decrease. This number of cycles has a design life after the battery is manufactured and cannot be changed.

Improper charging method: Improper charging method will accelerate the decline of battery life.

⌛For example, overcharging or over-discharging , when the lithium-ion battery is deeply charged and discharged, the structure of the positive and negative electrode materials may be destroyed, reducing the number of lithium ions, and thus causing its capacity to decrease; using inferior charging cables and chargers, the current is unstable, which can also cause damage to the battery.

It is especially recommended that, if conditions permit, you should firmly use the original charger of the same brand as the mobile phone . Because both the battery and the charger have battery management components inside, the original charger (including power bank) and the battery can interact effectively , automatically complete the management and protection of each stage of the charging process, and give priority to ensuring the battery life. The protection here includes the restorative charging process when the battery is too low, automatic stop charging when the battery is fully charged, and the automatic adjustment process of charging during battery use. Charging equipment of different brands lacks effective communication with the battery, which can be understood as a language barrier, thus greatly reducing the protection function of the battery.

⌛Overcold or overheated charging environment : Lithium batteries are extremely sensitive to temperature. Their normal operating (discharging) temperature range is between 0°C and 35°C. Whether it is high or low temperature, it will affect the operation of lithium batteries. High temperature has a particularly significant impact on batteries. When charging at high temperatures, the chemical reaction inside the battery will be more intense, generating more heat, causing the battery temperature to rise, which in turn damages the battery life.

Tips for Extending Battery Life

After understanding the life attenuation mechanism of lithium batteries, we can take some measures to extend the life of mobile phone batteries, and the most important thing is the "correct use of the charger (power bank)".

1. Strictly use original brand chargers and power banks

The charging process will effectively ensure the safety of the battery and will not overcharge. The 100% full charge displayed is just a display. In fact, whether you connect the battery or not, the charger will not charge the battery.

2. Don't charge the battery after it runs out of power

The lithium batteries used in modern smartphones do not have a "memory effect" and do not need to be fully depleted before recharging. It is recommended to charge the battery as soon as the battery level drops below 25% to maintain the battery's health.

3. Strictly use chargers with 3C certification

The original charger and charging cable have been strictly tested and certified to ensure the stability of current and voltage and reduce battery damage. If you are forced to use a charger of a different brand, you must choose a charger with 3C certification. But try to use it in emergency situations.

4Avoid long-term charging

If you are not using the same brand of charger, do not connect your phone to the charger for a long time, especially at night. It is recommended to charge your phone at a specific time and unplug the charger in time after it is fully charged. A simple way to judge: after the phone shows that it is fully charged, touch the charger after a few minutes. If it returns to room temperature, you can rest assured that it has stopped charging. If it is still at a high temperature, it means that there is no full-charge stop function, so unplug it as soon as possible .

5Avoid charging in high temperature or below 4 degrees Celsius

In hot weather, you should try to avoid charging your phone in the sun or in a closed environment. You can choose to charge it in a cool and ventilated place, and try to remove the phone case to help dissipate heat. In low temperature conditions, the slow chemical reaction will cause charging difficulties or even stop charging.

Note: The images in this article are all generated by AI

References:

Science Popularization China: Mobile phone batteries are not durable again. You have ignored these charging details...

Science Popularization China Network: Don’t play with your phone while it’s charging! If you want your phone’s battery to last longer, pay attention to these points

Science Popularization China: Your cell phone battery is not durable? You may be doing these 5 things wrong

Scientific enlightenment: How to save your mobile phone battery

Science and Technology Daily: Your mobile phone battery is dying quickly? That's because you charge it too much.