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18650 batteries - what are the differences


Bob Eisenman
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The owners manual for my Gotway Monster says the battery is composed of  18650 (lithium ion) Panasonic/Sanyo batteries. It does not indicate what type of 18650 cell makes up the battery.

A Google search on 18650 batteries indicates that the term 18650 physically means

18 mm diameter

65 mm long

O means circular

"The 18650 number means that it is 18mm in diameter, 65mm long, and the zero means it is a cylinder instead of a flat foil packet."
https://www.electricbike.com/lithium-cobalt-manganese/

The following table displays the various chemical configurations of lithium used in '18650' batteries.
https://batterybro.com/blogs/18650-wholesale-battery-reviews/18880255-battery-chemistry-finally-explained

70433.png

 

The following graphic shows the anode , cathode and electrolyte compartments in a battery attached to a circuit.  Differences between different 18650 battery types (ex. LMO or NCA or LCO) are the elements used in the cathode.

70438.png

 

'Half cell' reactions determine how and with how much energy the electron is liberated or reintegrated into or out of the circuit.
https://en.m.wikipedia.org/wiki/Lithium-ion_battery

"Electrochemistry :
The reactants in the electrochemical reactions in a lithium-ion battery are the negative and positive electrodes and the electrolyte providing a conductive medium for lithium ions to move between the electrodes. Electrical energy flows out from or in to the battery when electrons flow through an external circuit during discharge or charge, respectively.

Both electrodes allow lithium ions to move in and out of their structures with a process called insertion (intercalation) or extraction (deintercalation), respectively. During discharge, the (positive) lithium ions move from the negative electrode" "to the positive electrode (forming a lithium compound) through the electrolyte while the electrons flow through the external circuit in the same direction.[82] When the cell is charging, the reverse occurs with the lithium ions and electrons moved back into the negative electrode in a net higher energy state. The following equations exemplify the chemistry."
For LCO (lithium cobalt oxide) the half reactions are:

70440.jpg

 

The rate of ion diffusion in the electrolyte is temperature dependent. The lower the temperature the slower the rate of ion diffusion...so the rate at which electron delivery to the circuit (current on demand) and electron recovery from it becomes limited by the availability of diffused lithium ions and associated elements.

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A PDF master index URL

https://drive.google.com/file/d/0B9KXttJ6nbz6VWUtcUtvZEY3dWc/view

 

Edited by Bob Eisenman
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