li-ion battery 18650 battery Rechargeable Battery pack power supply for flash light

Battery Type	18650 2s1p
Nominal Capacity	4400mah
Nominal Voltage	7.4V
Max Charging Voltage	4.2 ±0.05 V
Discharge ending voltage	2.7±0.05 V
Standard charge current	0.2C
Maximum Charge current	5C
Standard Discharge current	0.2C
Max discharge current	0.5C
Max recommended charge and discharge cell surface temperature	Charge: 0~45℃ Discharge: -20~60℃
Storage temperature and time	1 year:-20~25℃ 3 months:-20~45℃ 1 month:-20~60℃
Cell dimension	Height : 50.5mm    Diameter: 18.5mm
Cycle Life	>500times

Battery researchers have been focusing on lithium metal electrodes as leading contenders for improving the amount of energy that batteries can store without increasing their weight. But lithium in this metallic form has a problem that has stymied much of this research effort: As the batteries are being charged, finger-like lithium deposits form on the metal surface, which can hamper performance and even lead to short-circuits that damage or disable the battery.

Now, a team of researchers at MIT says it has carried out the most detailed analysis yet of exactly how these deposits form, and reports that there are two entirely different mechanisms at work. While both forms of deposits are composed of lithium filaments, the way they grow depends on the applied current. Clustered, “mossy” deposits, which form at low rates, turn out to grow from their roots and can be relatively easy to control. The much more sparse and rapidly advancing “dendritic” projections grow only at their tips. The dendritic type, the researchers say, are harder to deal with and are responsible for most of the problems.