We are currently in the middle of a series on the manufacturing of lithium battery cells. In the first 2 articles we introduced the battery cell and looked at it a macro level. We looked at what processes are used to make a cell, how a battery is hermetically sealed, and the four main components of a cell (lithium, the metallic oxide cathode, the electrolyte, the metallic current collector. Now we want to look at the processes of battery cell manufacturing more closely by breaking down how the four main components of a cell come together.
Battery cell manufacturing processes begins with a lithium ingot. A lithium ingot is often times a cylindrical roll of lithium that weighs about 11 pounds on average. Special order ingots of course can be requested thereby changing the average weight.
Lithium ingots come from technical grade lithium carbonate which is a byproduct of lithium and a solution of lithium hydroxide. The conversion of lithium in the lithium hydroxide solution results in lithium carbonate as a fine white powder. This powder is placed into a billet container prior to being processed through the extrusion. The extruded billet may be solid or hollow in form, commonly cylindrical, used as the final length of material charged into the extrusion press cylinder. It is usually a cast product, but may be a wrought product or sintered from powder compact. This billet of lithium carbonate is the ingot.
As mentioned above the extrusion press – used to shape lithium by forcing it to flow through a shaped opening. The extruded lithium emerges as an elongated piece with the same profile as the opening. The shape is typically a thin piece of metal that stretches over 650 feet. Once the ingot is made the ingot is transformed by the extrusion press and accompanied roller system into a thin sheet of metal that is only 1/100th of an inch thick and 650 feet in length. A laminator furthers the process by stretching the 655 foot lithium roll to about 1.25 miles of lithium used to make 210 lithium batteries. The battery cell is then tested to measure 3.6V. Volts – or V – are an electrical measure of energy potential. You can think of it as the pressure being exerted by all the electrons of a battery’s negative terminal as they try to move to the positive terminal.
A punch machine is then used to cut the thin metal into the physical cell size requirements and a purification machine remove dirt and other unwanted particles.
In the next part of the series we will look at the metallic oxide cathode.
Until next time, Dan Hagopian – www.batteryship.com
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