Special size batteries do not have standard dimensions and are usually specially tailored to devices and equipment, assembled to a battery pack may well bring advantages because of the size. 

Li-Ion battery in special size 22650 with 3000mAh capacity and up to 15A discharge current.

Such cells are used in applications such as power storage, mobile energy, LED applications, model making, battery pack, etc. 
The cell has no integrated protection electronics, which is necessary for a safe use of Li-Ion batteries.
 

Safety instructions:

Lithium cells may only be operated with protective electronics!
Please note that lithium cells may only be used by qualified personnel.
Incorrect handling or short-circuiting may result in fire or explosion.

Further characteristics:

Lithium-ion batteries are thermally stable and are not subject to memory effect.
They work on the basis of lithium and are characterised by a high energy density.

Notes:

Charging lithium-ion batteries requires a special charger that charges the batteries according to a special charging procedure. (CCCV = constant current, constant voltage.) The batteries must not be charged above a voltage of 4.2 volts, otherwise there is a risk of fire and explosion. It is advantageous to charge the batteries only up to approx. 4.1 volts, as this significantly increases the service life or the number of charging cycles (possibly up to double). Only lithium-ion chargers may be used for charging. However, the cheap chargers sometimes have the disadvantage that they do not switch off safely at the end of the charging process, but continue to charge the batteries with a small charging current, which can be dangerous.

Furthermore, rechargeable batteries and batteries do not belong in household waste! Please dispose of them as prescribed by law at the municipal collection points or in the [usually green] containers provided by retailers.