What is Lithium-ion battery (Li-ion)?

Lithium-ion batteries are popular due to their light weight, high capacity, and lack of memory effect. Many digital devices rely on them despite their higher cost, and they boast a higher energy density than Nickel-Metal Hydride batteries, with up to double the capacity for the same weight. Low self-discharge rate and no “memory effect”, in addition to not having toxic substances, enhance their appeal even further.
Moreover, lithium batteries are generally marked with English 4.2Vlithiumion battery (lithium battery) or 4.2Vlithiumion secondary battery (lithium secondary battery), or 4.2Vlithiumion rechargeable battery (rechargeable lithium battery).
Today, we will discuss the differences between 18650 and 26650 lithium batteries. Here is a simple table that you can look at very quickly, then you will be clear.

It is clear from the QUICK COMPARISION TABLE that the main difference between 18650 and 26650 batteries is size and capacity. The 26650 is larger and has a larger capacity than the 18650, but it is also heavier and more expensive. Portable electronics mostly use 18650 batteries, while high-performance flashlights and power tools use 26650 batteries.

1.What is 18650 lithium battery?

The 18650 lithium battery is a standard lithium-ion battery model designed by SONY of Japan. It is the world’s first lithium-ion battery.

2. What does “18650” mean?

Here is the basic naming rule for cylindrical lithium batteries. 18650 refers to a battery with a diameter of 18mm and a length of 65mm, while 0 represents a cylindrical battery with a diameter of 18mm and a length of 65mm. The model of the No. 5 battery has a diameter of 18 mm and a length of 65 mm. With a diameter of 14 mm and a length of 50 mm, it is 14500.

3.18650 Lithium Battery Overview

The most common 18650 batteries are Li-ion batteries and LiFePO4 batteries.
Lithium ion 18650 battery charger
Nominal voltage :3.7v
Charging cut-off voltage： 4.2V.
For 18650 LiFePO4 batteries
Nominal voltage: 3.2V
Charging cut-off voltage: 3.6V
Capacity: usually 1200mAh-3350mAh
The common capacity: 2200mAh-2600mAh
Cycle life: 1000 cycles of charging

4.What are 18650 lithium battery used in?

The 18650 lithium battery is commonly used in high-end glare flashlights, portable power supplies, wireless data transmitters, electric heating, warm clothing, shoes, portable instruments, portable lighting equipment, portable printers, industrial instruments, and medical instruments.
18650 batteries are widely used in major electronic fields because of their high capacity and stability at work.
The lithium battery standard 3.7V or 4.2V is the same. The only difference is the manufacturer’s label.
3.7V refers to the platform battery book (an atypical battery book) discharged during battery use, while 4.2V refers to the fully charged battery.
The 18650 lithium battery is commonly used in high-end glare flashlights, portable power supplies, wireless data transmitters, electric heating, warm clothing, shoes, portable instruments, portable lighting equipment, portable printers, industrial instruments, and medical instruments.

5.Advantages of 18650 lithium battery

Large capacity
When combined into a 18650 lithium battery pack, the capacity of the 18650 lithium battery pack can easily break through 5000mah, whereas the general battery capacity is only 800mah.
Long life
During normal use, the 18650 lithium battery can reach a cycle life of more than 500 cycles, which is more than twice that of ordinary batteries.
High safety performance
For one thing, 18650 lithium batteries do not explode or catch fire. On the other hand, they are non-toxic and non-polluting.
A galvanized steel shell withstands inner pressure, so it won’t explode.
In addition, 18650 lithium batteries have been RoHS (Restriction of Hazardous Substances) certified.
It has a cycle count of more than 500, and the power-up efficiency can reach 100% even at 65°C. It has good high temperature resistance.
18650 lithium batteries have separate positive and negative electrodes in order to prevent short-circuiting. Therefore, short-circuiting is extremely unlikely.
A protective board is installed inside the battery to prevent overcharging and overdischarge. This method can also prolong the battery’s life.
High voltage
Nickel-cadmium and nickel-metal hydride batteries have 1.2V voltages, while 18650 lithium batteries have 3.6V, 3.8V, and 4.2V voltages.
No memory effect
Lithium 18650 batteries do not need to be drained before charging, making them easy to use.
Small internal resistance
In comparison to ordinary liquid batteries, polymer batteries have a smaller internal resistance. It is even possible for domestic polymer batteries to have an internal resistance of less than 35mW, thereby extending the standby time of the mobile phone and reducing self-consumption.
This type of polymer lithium battery that supports large discharge currents is an excellent choice for remote control models, and has become the most promising alternative to nickel-metal hydride batteries.
Wide range of use
The 18650 battery can be used in notebook computers, walkie-talkies, portable DVD players, instrumentation, audio equipment, model aircraft, toys, video cameras, digital cameras, and other electronic equipment.
Flexible Design
18650 lithium batteries can be combined in series or parallel

6.Disadvantages of 18650 lithium battery

Its volume has been fixed
In some notebooks or products, the 18650 lithium battery is not well positioned due to its fixed volume and its fixed volume.
Of course, this disadvantage can also be said to be an advantage. This disadvantage is compared to the customizable and changeable size of lithium batteries such as polymer lithium batteries. When compared to some products that have battery specifications specified, it has become an advantage.
The 18650 battery must be equipped with a protective circuit board
18650 lithium batteries require a protective circuit to prevent overcharging and discharge.
It is necessary for lithium batteries to do this, which is also a disadvantage of lithium batteries, since the materials used in lithium batteries are mostly lithium cobalt oxide materials, and lithium cobalt oxide materials cannot be discharged at high currents, and their safety is poor.
Relatively Expensive
As compared with general battery production, 18650 lithium batteries have high production conditions, which undoubtedly increases production costs.

7.What is 26650 battery?

A 26650 lithium battery has a diameter of 26mm and a length of 65mm. The definition law for its model specification is: 26650 type, which means it has a diameter of 26mm and a length of 65mm. INR26650-3.6V-4500mAh lithium batteries and IFR26650-3.2 V-3200mAh lithium iron phosphate batteries are common lithium batteries.

8.What are 26650 lithium batteries used in?

There are many applications for 26650 lithium batteries, including power tools, lighting, landscape energy storage, electric vehicles, toys, instrumentation, UPS backup power supplies, communication equipment, medical equipment, and military lamps.

9.26650 lithium battery overview

Performance: 2000 cycles (1C charge/1C discharge, capacity retention rate 80%, DOD 100%)
Maximum continuous discharge current: 9.6A
Pulse discharge current: 15A, 5s
Operating temperature: charging: 0°C~55°C; discharging: -20°C~60°C
Storage temperature: -20°C~45°C
Battery weight: 86 g (approximately)
For 18650 Ternary lithium-ion 26650 single cell
The nominal voltage: 3.6V
Nominal capacity: 4500mAh (capacity range 4500-4650mAh)
AC inner limit: ≤30mQ (plus PTC type)
Charging conditions: cut-off voltage 4.2±0.05V, cut-off current 0.01C. (Remarks: Charge at a constant current of 0.5C to 4.2V, and charge at a constant voltage until the current drops to 0.01C cut-off)
Discharge cut-off voltage: 2.75V
Cycle performance: 500 times (1C charge/1C discharge, capacity retention rate ≥70%, 100% DOD)
Maximum continuous discharge current: 13A
Pulse discharge current: 15A, 5s
Operating temperature: charging: 0°C~55°C; discharging: -20°C~60°C
Storage temperature: -20°C~45°C
Battery weight: 92 g (approximately)
Diameter: 26.2mm Height: 65.6mm

10.Advantages of 26650 lithium battery

1.Performance of overcharged batteries: The battery’s initial state is measured after it has been charged according to the standard.
Observe the changes in the battery’s appearance when it is charged at a current of 3C to 10.0V, then at a constant voltage to terminate at a cutoff current of 0.01C.
There was no fire or explosion as a result.
2.Battery overdischarge performance is measured after the battery is charged according to the standard.
You can observe the changes in the appearance of the battery when it is discharged at 0.5C to 0V in a normal state.
There was no fire or explosion as a result.
3.External short circuits are difficult to perform: When the battery is dry and explosion-proof in the center, its positive and negative electrodes are directly shorted when the battery is dry and explosion-proof (the total circuit current is not greater than 50 mQ).
When the battery temperature drops to about 10°C below its peak temperature, the test ends. Observe the battery temperature and appearance.
There was no fire or explosion as a result.
26650 lithium battery disadvantages
As the 26650 lithium battery has a small range of use and its performance status has been replaced by the 18650 lithium battery, many manufacturers no longer produce it.
There are two types of cylindrical lithium batteries: the 26650 lithium battery and the 18650 lithium battery. So, what are the differences between them? The differences between 26650 lithium batteries and 18650 lithium batteries are explained below.

11.18650 VS 26650 The difference between 18650 and 26650 batteries

1.Differentrated capacity:
26650 has a rated capacity of 3000mAh,
18650 batteries have a capacity of 1100~1400mAh.
26650 batteries have a higher capacity than 18650 batteries when the same battery material is used. Assuming the same ternary material is used, 26650 batteries are generally rated at 5200mAh, while 18650 batteries are typically rated at 2600mAh.
2.Differentdiameters of the two batteries:
26650 has a diameter of 26 millimeters
18650s have a diameter of 18 mm.
3.Different reference quality:
26650 production test quality is 94 grams
45 grams is the quality of the 18650 production test.
4.Different battery volume;
26650 has a larger volume than 18650.
Their cell heights and diameters are the same.
26650 batteries have a 26mm diameter, while 18650 batteries have an 18mm diameter. 26650 batteries are 8mm wider than 18650 batteries.
5.Different battery capacity;
Under the same battery material, 26650 has a larger battery capacity than 18650.
26650 batteries with the same ternary material usually have a capacity of 5200mAh, while 18650 batteries have a capacity of 2600mAh.
6.Different applications;
Lighting batteries, industrial lithium battery packs, power tool batteries, electric bicycle batteries, power lithium battery packs, etc., use 18650 lithium batteries.
Integrated solar street lamp lithium battery packs, energy storage stations, solar energy storage batteries, etc., use 26650 lithium batteries.
7.Different battery life:
In comparison to 18650, 26650 is 18MM long and 65MM high, which means there is more space to fill the material and achieve a greater capacity.
Currently, 18650 batteries have capacities of 2200, 2600, 3100 MAH, etc.
Generally, 26650 batteries have a capacity of 4000, 4200, or 4500 mah,
As a result, the battery life will be longer.