18650 and Lithium-ion Batteries: How do they work?


Written by: Aaron Adrian, founder of juicedbatteries.com

 

Knowing how Lithium-ion and 18650 batteries work can provide an enormous benefit. After reading this article, you will understand how to increase battery life, have longer life cycles, and have a better understanding of what causes explosions (and how you can prevent it, too). 

 

Before lithium-ion batteries, there were no rechargeable batteries. Li-ion technology made it possible for phones, laptops, and of course vape devices, to be able to withstand high-drain discharges, while also easing it's effect on the environment because you don't throw them away after a single use. 

So how do lithium-ion and 18650 batteries work?

In conventional batteries, the energy and chemical reactions only work once; they are fully charged when you buy them (with all it's energy in the negative end, the anode), then once the battery has discharged all of it's energy, it's toast. Done for.

However, with lithium-ion batteries, once the battery is discharged completely (with all of the li-ion molecules on the positive end, the cathode), it is able to reverse the reaction. When charging, the li-ion molecules are "carried" by electrolytes, from the cathode (positive end), to the anode (negative end). Once the lithium-ions have been "dropped off" at the anode, it is now fully charged. 

How Lithium-ion batteries work

 

 

Why do lithium-ion and 18650 batteries eventually fail?

There are a number of reasons a battery can fail (which in turn, may explode or vent). The top reasons for battery failure are short-circuiting, discharging the battery past it's rating, and overcharging. All of these can be very dangerous, as usually a lithium-ion battery will explode or catch fire if these things happen. 

Also, if a battery is punctured, it will short-circuit because the positive and negative sections of the battery will touch, causing the battery to discharge all of it's energy. When a battery overheats, it is called "Thermal runaway". Remember that electrolyte, which carries the lithium-ions back and forth? Yeah, that electrolyte is actually a very combustible liquid similar to gasoline and paint-thinner. So when a battery enters thermal runaway, or overheats, the electrolyte liquid catches fire which is what causes the fire and/or explosion. 

How can I prevent thermal runaway? 

You can prevent this from happening by a number of things;

1) If your battery wrap is damaged or torn, replace immediately. Even a slight tear in the battery wrap can cause a short-circuit.

2) Never overcharge your batteries. Buy "smart" lithium-ion chargers which cut off charging once it has reached it's full capacity. 

3) Never discharge a battery past it's rating or use if it's dead. Do not trust the ratings on the battery wrap, find out it's true rating by researching online. Many companies, most notably Efest, MXJO, AWT, TrustFire, etc. are Chinese-based companies that inflate the actual ratings. So a "40A" battery will actually be a "20A" battery. Only buy from companies that are honest about their ratings, like us, Juiced Batteries.

4) Never store lithium-ion or 18650 batteries in your pocket, purse, or backpack (unless in a protective plastic casing). Most cases of battery explosions were caused by keeping the battery in a pocket without protective casing. When a battery is by itself in a pocket, all it takes is one piece of metal that touches the positive end to cause a short-circuit. Always keep your batteries in a made-to-fit plastic casing, and never leave them by themselves without protection.

 

Also note, if your batteries feel warm, stop using until they cool off. If you notice an unusual smell while using IMR li-ion batteries, stop using immediately and replace the battery. 

 If you're not sure what IMR means, check out this article

By now, you understand how lithium-ion and 18650 batteries work. You also have more knowledge into what causes these batteries to explode or catch fire. 

Please leave a comment! Tell us what you liked about this article, why you use lithium-ion batteries, and whether or not you've ever experienced thermal runaway!

 

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