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I’m new to electricity, and I’ve got a question about electrons flow inside a Li-on battery. A lot of articles and videos show us only Li+ ion flows from anode to cathode through electrolyte during discharging of battery. But there is no info about e- flow from cathode to anode inside battery. As I know, there must be closed loop of electrons flow, but also there is conception that separator doesn’t let e- to flow through electrolyte. So how electrons pass through Li-on battery to comply with close loop conception?

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Always there must be a complete circuit: a closed loop of flowing charges. But no electrons flow in electrolytes. The amperes inside the battery-electrolyte are composed of flowing charged atoms; the lithium ions.

Flows of positive charge are opposite that of electrons in wires. Of course this means that, inside the battery, at one electrode surface, the +Li and the electrons are coming together and canceling out, forming neutral lithium atoms. And at the other electrode, Li atoms are donating extra electrons to the metal surface, then corroding away as +Li ions, and flowing off into the electrolyte as amperes of current.

Amperes are the coulombs of charge flowing per second. NOT just electrons flowing per second. The coulombs of charge can be ANY mobile charged particle, and conductive salts/acids/humans contain no mobile electrons to do the flowing. (Only electrons alone are flowing ...inside metal conductors. Instead make that solid, unmoving metal conductors. If your conductors are liquid metal, or are vibrating metal, then the protons within the positive metal ions are moving as well. For amperes made of pure electrons, your metal conductors must be both solid and static.)

Non-electron currents? They're extremely common. Whenever a human gets zapped by high voltage, no electrons flowed through their body. The amperes inside human tissue was made of flowing +Na, +K, -Cl, +H, OH ions only. And current in the ground (damp dirt) has no electrons, just ion-flows. And in lead-acid batteries, all the amperes within the battery acid are actually made of flowing protons! (Same thing happens inside fuel cells, where the electrolyte-layer is a proton conductor or "solid acid" material.)

If you find a textbook which claims that electrons flow through salt water or through acid, throw that book away! That single misconception is bad enough, but probably the same books has even worse mistakes. Once they get into your brain, you may never get them out again. Heh, even better, chop that book up before throwing it away, so it can never harm the mind of anyone who someday finds it in the trash...

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There does need to be a closed loop for electrons to flow, but it doesn't need to be inside the battery.

The electrons flow through the external circuit, "forced" by the battery. The current flow inside the battery is in the form of Li+ ions.

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