Swollen batteries are a common occurrence for almost anyone who has owned a smartphone or any Lithium-ion battery-powered device. The sight of a swollen battery is usually not a pretty one and what most people would like to know is why batteries swell and how to prevent them.

To do this, we will first tackle the question, of why batteries swell and how to prevent them will follow up next.

How Batteries work

The batteries on our smartphones are rechargeable. This means that you can recharge them even after they have run out.

How Smartphone Batteries Work
Credit: Australian Academy of Science

It works using a very simple principle. The battery itself is divided into 2 half-cells, one side being positive (cathode) and the other side being negative (anode). When the battery is full, all of the electrons are stored on the negative side of the battery. For the battery to work, the electrons must flow (current) out of the negative side (anode) and power the load. After this is done, the electrons then flow out to the positive side of the battery (cathode).

To recharge the battery, the electrons must be forced to return to the negative side (anode). This is done by plugging in a charger which reverses the polarity of the battery and forces the electrons to return to the negative side.

See:  How do smartphone batteries work?

Chemical causes of battery swelling

Now that we know how batteries work, it is important to note that this process is a chemical one. Therefore each recharge and discharge is a chemical reaction. Over time, these reactions are no longer fully completed. This is because the electrolyte that holds the electrons begins to decay. As it decays, it starts to release gases. When enough gases are released, they force the battery cases to bulge.

Human Causes of Battery Swelling

It is a given that all batteries will age with time. Their electrolytes will decay, and release gases, and the battery will lose all its capacity. This usually happens after a certain amount of charge cycles are reached. However, human misuse or overuse can speed up this process and cause the batteries to bulge sooner than expected.

The 5 main ways by which are:

  1. Overcharging: This is when an individual keeps their batteries at 100% for extended periods. This puts a lot of pressure on the electrolyte on the anode side of the battery, causing the electrolyte to degrade.
  2. Over current: If you use a charger with a higher current rating than your battery can handle or if you connect too many devices or draw too much power from a battery at once, it won’t be able to handle the excessive load. This excess demand for electricity leads to over current or overloading. This is especially true for powerbanks and less so smartphone batteries.
  3. Extreme temperature: Allowing your phone/power bank to heat up either by using or charging in a hot environment is a terrible idea. Heat causes the battery electrolyte to degrade very quickly.
  4. Physical damage: Physical damage to the battery could cause it to short-circuit or bend out of shape. This could impact the battery and force it to age rapidly.
  5. Poor build quality: substandard power made by unscrupulous manufacturers will age quickly and swell faster than normal.

How To Prevent Battery Swelling

  1. Avoid overcharging: Avoid overcharging your batteries or keeping them at 100% for an extended period.
  2. Avoid overcurrent: Avoid using chargers with current/voltage ratings that your phones/powerbanks are not designed to handle. Also, avoid overloading your powerbanks as well.
  3. Avoid extreme temperatures: Do not use or charge your phones and power banks when they are hot, or when the temperature is very high.
  4. Avoid physically damaging your batteries
  5. Avoid batteries and powerbanks with poor build quality

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