A guide to power bank and mobile phone maintenance in the “post-Romoss” era

Before reading this article, ask yourself a question:

When was the last time you bought a new power bank?

If it was two years ago, you need to pay more attention.

In the past two weeks, the topic of power banks has been making a lot of noise. People have become nervous from airports to subways, as if the uncertain factors in everyone's pockets suddenly increased overnight.

Image | China National Radio Network

Although the problems with power banks themselves have temporarily come to an end, and several involved enterprises have each proposed solutions, it remains to be seen how the supply chain with exposed problems will be dealt with and rectified later. However, we need to focus on a broader issue behind this event:

The lifespan of power banks is not infinite - all lithium - battery products around us are consumables.

Power banks have a shelf - life

The main culprit of this large - scale power bank quality problem is a battery cell subcontractor in the power bank parts supply chain. According to reports, this subcontractor illegally replaced the separator material between the positive and negative electrodes of the battery cells during the production of a certain batch, resulting in unqualified separator quality.

Power bank products using these problematic battery cells entered the market around the beginning of 2024. Due to the unqualified separators, a series of subsequent problems such as overheating, swelling, and even smoking and catching fire occurred in the power banks, ultimately triggering recent social events such as power bank recalls and embargoes.

As shown in the schematic diagram, the "separator" is an indispensable material inside every lithium - ion battery. They not only need to maintain their physical and electrochemical properties stable in the highly corrosive electrolyte but also need to achieve a balance between thinness and puncture - and stretch - resistance performance. Only in this way can they maintain the efficiency of free lithium - ion flow (i.e., charge - discharge efficiency) while keeping the battery stable during daily bumps.

However, if the subcontractor in the supply chain switches back to the qualified separator material specified for production, can we rest easy with our various power banks? The answer is also no. Because the working principle of lithium - ion batteries has determined that no matter how excellent the craftsmanship of each battery is, it will ultimately have a lifespan limit.

To understand how the "lifespan theory" of batteries comes about, we need to have some basic knowledge of the working principle of batteries. Taking the portable power banks with large - scale problems this time as an example, regardless of external factors such as the shell, interface, charging protocol, and battery cell layout, they are essentially the same type of thing: rechargeable lithium - ion batteries.

As a secondary battery (rechargeable battery), lithium - ion batteries can be repeatedly charged and discharged, relying on these positively charged lithium ions that flow freely in the electrolyte. They migrate from the positive electrode to the negative electrode when subjected to an external voltage and move from the negative electrode to the positive electrode when releasing voltage externally, thus completing the simplest "charge - discharge" cycle. In terms of principle and process design, these chemical reactions are completely reversible.

However, in the real usage environment, it is impossible for all free lithium ions to complete the intercalation and de - intercalation between the positive and negative electrodes of the battery. There are mainly two reasons: extreme temperatures or over - charging and discharging. These two factors will disrupt the designed reaction process, causing some lithium ions to undergo an irreversible chemical reaction with the negative electrode material, precipitate from the electrolyte, and form a solid deposit on the negative electrode material.

This fatal irreversible chemical reaction, also known as "lithium plating," is the main culprit for the limited lifespan of lithium batteries.

However, why is lithium plating so fatal? The reason lies precisely in the positive - and negative - electrode separator mentioned earlier. When lithium ions continuously precipitate from the electrolyte and deposit on the negative electrode material, they will spontaneously form sharp dendritic metallic lithium, called lithium dendrites. As the deposited lithium increases, these lithium dendrites will eventually grow to a sufficient height, squeeze and pierce the separator, causing a short - circuit between the positive and negative electrodes, and then -

In the power bank accident this time, because the separator material itself was unqualified, the separator was more likely to be pierced by lithium dendrites earlier or damaged and short - circuited due to external forces. Eventually, these power banks malfunctioned collectively after just over a year of product life.

However, even if there is no problem with the separator material, as the power bank is used normally, lithium dendrites will eventually pierce the separator or other internal materials of the battery cell one day. "Lithium plating" is like the Sword of Damocles, hanging not only over every qualified and unqualified power bank but also over every mobile phone in our hands and every lithium battery commonly seen in life.

How to protect lithium batteries

The trouble with "lithium plating" is that it is an inevitable product of chemical reactions in non - ideal environments. Unless there is a fundamental change in the positive - and negative - electrode materials or the working principle of the battery, it cannot be avoided.

Moreover, it is not the only challenge that lithium batteries face during their life cycle. For example, inactivation caused by long - term high temperatures, oxidation of the external battery contacts, and even the simplest moisture corrosion are all problems we must pay attention to.

After all, in the humidity of the "returning south" weather, your chemical energy is beyond your imagination

In other words, when each lithium - ion battery leaves the factory, there is already a small alarm clock inside starting to count down. No matter how carefully we use it, at most, we can only slow down the speed at which the alarm clock reaches zero.

Of course, things are not as pessimistic as they seem. Because as long as the operation method is appropriate, the "working life" of a lithium battery can be extended for a very long time. Compared with the power banks we carry around occasionally, what we really need to pay more attention to are the old mobile phones or old tablets at home -

If you also have some similar collection hobbies, you need to be more careful

Although from a hardware perspective, smartphones produced in the past decade basically have a certain battery protection mechanism inside, the average lifespan of a general mobile phone lithium battery is 300 to 500 charge - discharge cycles. Converting the daily usage frequency, it is about two to three years.

After that, although the lithium battery will not immediately show obvious physical changes, phenomena such as a decrease in total capacity, unstable voltage, and difficult charging are almost inevitable.

Therefore, although we mostly do not use these old devices intensively, if we want them to accompany us for a long time and maintain the state of occasionally lighting up the screen to recall the past, we must pay attention to their daily maintenance.

1. Lithium batteries with physical abnormalities

If the battery of your old electronic device at home has shown physical changes, such as swelling, leakage, emitting an odor, or abnormal heating, don't hesitate. Remove them immediately. The purpose of doing this is not only to protect the electronic device itself but also to avoid dangerous battery phenomena such as fire and explosion at the source.

There is even a special term for a swollen battery: spicy pillow

Different from a simple short - circuit caused by lithium plating, battery swelling is due to the abnormal long - term chemical reaction between the positive and negative electrodes, which causes gas to accumulate inside the battery. It is not only more susceptible to external forces. When the swollen battery bursts, the airflow and exothermic oxidation may not only cause the battery to "catch fire" but also turn it into a flame thrower due to air pressure, which is much more dangerous than simple self - combustion.

More importantly, when you find that your battery has swollen, never manually disassemble the battery casing or puncture the swollen part to release the gas. As mentioned before, once the positive - and negative - electrode materials suddenly come into contact with air, a violent exothermic oxidation reaction may occur. Combined with the sudden decrease in air pressure, it is like a homemade incendiary bomb.

If conditions permit, try to take the swollen battery together with the electronic device to a mobile phone repair shop or other places that specialize in handling electronic waste and ask an experienced master to help remove the battery. It is best to seek help from professionals for such operations with a risk of combustion. Don't just throw it into the trash can casually, as it will only cause trouble for others.

In addition, a swollen battery cannot be discharged by soaking it in saltwater. Once the outer casing is damaged, the internally accumulated gas and the positive and negative electrodes will come into contact with water, which may easily cause an explosion and combustion.

For those power bank products in the recall sequence, be sure to follow the manufacturer's instructions. First, check if there is any physical deformation on the appearance, and then strictly follow the guided steps to perform the salt - water soaking and destruction operation:

2. Aged but functionally normal batteries

Compared with swollen batteries, this type of battery without physical changes but with significantly degraded performance is more common for us to encounter, and the treatment method for them is relatively simpler.

First, if you use these old electronic devices occasionally and charge and turn them on every once in a while, you don't need to take too many special precautions. Just remember the following points:

- Avoid over - charging and discharging. It is best to take them out and recharge them to about 80% every one to two weeks. For example, you can use the battery health function of your mobile phone to lock the maximum charge at 80%. If the discharge speed of the battery can no longer be controlled, it is recommended to remove the battery for separate storage or replace it with a new one.

- Avoid extreme temperatures and high - humidity environments. An electronic product moisture - proof cabinet or moisture - proof box with constant temperature and moisture - proof functions is the best choice. If your budget is limited, a well - sealed storage box plus a desiccant is also very effective.

- Pay attention to the physical changes of the battery. If you find phenomena such as swelling in the electronic device, it is better to ask a repairman to remove or replace the battery as soon as possible.

Second, if you have confirmed that you will no longer use the device, or if the device itself has problems and you keep it more for the sake of nostalgia, then a ready - made picture frame is a good choice. It can not only display the device more prominently but also give you a last sense of participation:

Even if you are too lazy to do it yourself, there are many services on e - commerce platforms that can disassemble and frame the device for you. We only need to pay attention to subsequent moisture - proofing.

3. Electronic devices in use