Each of these chemistries has its own advantages and disadvantages. I'll go through each of the chemistries and their popular 18650 models. First, let's understand what exactly these names mean...

What's in a name?

An 18650 li-ion battery consists of three parts: the cathode, the anode, and the electrolyte.

The anode of all 18650 li-ion batteries is basically the same: carbon/silicon and graphite. The cathode, however, is where batteries differ, and it's what gives each model its unique characteristics. The chemical formulas in the table refer to the battery's cathode.

One of the trade-offs with cathode chemistry is between energy, capacity, cycle life, and safety. For instance, ICR (cobalt-based) chemistries are both high energy and high capacity, but not very safe. IMR is safer, but has lower capacity than ICR. Adding nickel to manganese (IMR) gives it a higher specific energy.

Now that we know what each chemistry means, let's look at each specific chemistry.

IMR - LMO - Li-manganese

Many of the high-drain batteries used in vaping and flashlights have IMR chemistry. The reason is that manganese is awesome. It allows your battery to discharge at a high current while maintaining low temperatures. This means that it's safer than many of the older ICR batteries. Most IMR batteries don't require extensive built-in protective circuitry. 



(Pictured: LG HB2, an IMR 18650 battery)

However, most modern high-drain batteries add nickel to the mix...

INR - NMC - Lithium manganese nickel

The reigning champ of the 18650 vaping world. This chemistry adds nickel to the IMR chemistry above, making it a "hybrid" chemistry. It combines the safety and low resistance of manganese and the high energy of nickel.

(Pictured: Battery Bro Samsung 25R. Wink, wink!)

The resulting battery chemistry gives you a reasonably high capacity and a high discharge current. Importantly for vapers, the chemistry is very stable, meaning that you don't need expensive built-in protective circuits. 

There is extensive innovation within this chemistry as well. Sony, Samsung, and LG are all developing next-gen INR batteries with different ratios of manganese, nickel, and cobalt. We at Battery Bro have high hopes for this category.

Popular INR 18650 models:

• Samsung 25R
• Sony VTC4
• Sony VTC5
• LG HE2

NCA - Li-aluminum

This chemistry is similar to INR, but without the benefit of manganese. These batteries tend to support lower discharge currents, but make up for it with great capacities and cycle life. They also tend to be more resistant to physical shock, making them good options for e-bikes. Tesla uses them for its awesome electric cars.

Popular NCA models:

• Panasonic 18650PF
• Panasonic 18650B
• LG MH1

NCO

This is a very rare chemistry. The only model I can find is the Samsung 29E, which has 2900 mAh and a max continuous discharge current of 8.2A.

ICR - LCO - Li-cobalt

The big boys! This chemistry delivers the highest specific energy of any 18650 battery chemistry - but at a cost. They are the most dangerous li-ion 18650 batteries out there. This is also a problem for high-current discharging, as you can't safely discharge them at a higher current than their mAh rating.

If you use them in personal vaporizers or flashlights, for example, you'll want a model with built-in protective circuitry - which most often must be added by a third-party company like Trustfire. 

These batteries are not good for PVs or flashlights, for example, but you might have them in your laptop. Good, cheap batteries - but finicky.

IFR - LFP - Li-phosphate

These batteries are excellent in many ways, but their low (3.2V) voltage prevents them from joining the high-drain club. They also self-discharge at higher rates than other chemistries. On the flip side, they have high current ratings, even getting up to 30C, while still maintaining somewhat high capacities.