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What is the makeup of a typical 18650 battery?

Discussion in 'Battery Discussion' started by tander, Aug 8, 2014.

  1. tander

    tander Member

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    Hi all, this is probably a silly question, but I was thinking about the gigafactory etc. and I realized I don't really even know what goes into an 18650 (which is terrible because I even remember seeing a video of the battery assembly gizmo machine Tesla uses). I know that they can differ depending on who's making them and probably what the purpose is, but google failed to show me a pie chart or something that says 18650s are x% lithium, x%nickel etc? Can anyone enlighten me or have a good link? Thanks.
     
  2. flashflood

    flashflood Member

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    Battery University is a good resource in general. Here's a place to start:

    Types of Lithium-ion Batteries – Battery University
     
  3. rabar10

    rabar10 FFE until Model 3

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  4. tander

    tander Member

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    Thanks, so is lithium considered the active material or the electrolyte (I obviously still have a lot to learn)?
     
  5. daniel Ox9EFD

    daniel Ox9EFD Member

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    Tesla uses a NCA cathode and graphite anode. NCA is considered relatively volatile yet energy dense, compared to NMC which is the automotive standard.
     
  6. Nubo

    Nubo Test Mule

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    #6 Nubo, Sep 1, 2014
    Last edited: Sep 1, 2014
    Lithium is not used as a reactant, but rather the charge carrier; more specifically, Lithium ions. Charge/discharge is basically just movement of those ions from one side of the battery to the other. There isn't "active material" in the same sense as other batteries where energy is stored and released by virtue of chemical reactions. In fact, Lithium's marked tendency to react presents a difficulty.

    The electrolyte serves as a medium through which the Lithium ions can migrate. It also serves a secondary purpose in that reaction of the electrolyte forms a "solid electrolyte interphase layer" -- a hard goo that is at once a blessing and a curse. It's a blessing because it tends to stabilize the carbon electrode and keep it from fracturing from the ion migration. It's a curse because it eventually thickens and blocks too much of the ion migration.
     

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