3: Types of lithium-ion batteries

Classification by shape

Cylindrical type
Cylindrical type is the lowest cost andthe highest capacity, but when combining cells gaps will form and density will be smaller.The common size is 18650.

Square type
Aluminum cans are the mainstream for square type.
Caution is needed because polarity of battery is the opposite between iron can and aluminum can.
Consideration is needed in design because it may swell with charge and discharge cycles.

Laminated type
The laminated type is called a lithium polymer battery which that uses a film for the exterior, and it contains gelatinous electrolyte, but it may expand due to charge and discharge.

Positive electrode material
Cobalt type
Manganese series
Nickel type
Composite material


Composite materials such as nickel and cobalt, manganese and so on are the mainstream for the positive electrode material of lithium-ion batteries.

Nickel cobalt type is used for high capacity lithium-ion batteries (NCR series such as NCR18650BF), and nickel manganese type is inexpensive and is used for general lithium-ion batteries (UR series such as UR18650ZY).

Negative electrode material
Graphite type
Coke (carbon) type


The negative electrode material is made of carbon material but especially of graphite and coke of different structure.
Each company is researching about special carbon materials with excellent capacity and low temperature performance.

Size description
The size of the cylindrical lithium-ion battery is written as follows.
Diameter (in mm) + length (in 0.1mm)
Example 18650: diameter 18mm, length 65mm

Since there is a slight error, in the case of 18650, each company differs between 17.9mm and 18.3mm.
Size description of square lithium-ion batteries and lithium polymer batteries is different for each manufacturer.



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