This part is a kind of semiconductor called ICR18650-26A.

Function of this product has Lithium-Ion-Battery.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

data sheet system: nominal voltage: end charge voltage: max. charge current: charge conditions: standard charge: fast charge: charging method: capacity: nominal: minimal: max. discharge current: life time expectancy: ambient temperature range: charge: discharge: long term storage: Lithium-Ion-Battery 3,7V 4,2V 2600mA (ambient temperature 25°C) 1300mA for 3,5h min. 2600mA for 2,5h min. CC-CV (constant current and constant voltage) after standard charge 2600mAh at 0,2C discharge to 2,75V 2550mAh at 0,2C discharge to 2,75V 3600mA (ambient temperature 25°C) > 300 cycles 0…45°C -20…60°C -20…45°C (less than 3 months) -20…25°C (less than 1 year) approx. 47g h1 max. 70,2mm d1 max. 19,0mm 22 AWG 90mm±5mm long open ends 3mm ±1mm tinned (ends isolated for short circuit protection) w [ ... ]

ICR18650-26A PDF Datasheet Download