When electrons reenter the battery, how do the chemicals inside the battery change the electrons?

Also I know electrons flow from high potential to low potential, but what do the electrons lose that they need to regain in the battery?When electrons reenter the battery, how do the chemicals inside the battery change the electrons?
The best thing you can do is look up a diagram of a lithium ion battery.



The electrons start out in lithium cobaltate, which releases a lithium ion (into the battery) and an electron (into the external circuit).When electrons re-enter the battery, they combine back with lithium ions and get absorbed by carbon (graphite).