Generally yeah - it is both willing to give up and take back electrons pretty easily (so, discharging and charging) but in the modern era another really important factor is that it balances having these properties and also being very light relative to the amount of energy it can hold in a battery. Good for portable applications like cell phones, cars, etc.
Lithium is at the top, so you get the most voltage per molecule.
Then there’s other factors like discharge recharge, temperatures, all that, but lithium is basically the best if you can get the other factors to play nice too:
That was covered in my college chemistry class, but I took it 25 years ago and don't really remember the details. Electro negativity comes to mind, but I might have the terms wrong. In any case the laws of chemistry apply.
Is is that it freely ejects electrons at a higher rate than other materials, given a certain catalyst?