I just sold my 2014 Leaf for close to what I paid for it 5 years ago. It was cheap transportation for 5 years. Basically zero maintenance costs and only a few dollars to charge it up each time. My Leaf still had close to a 70 mile range when I sold it. I always trickle charged it, never hit it with a rapid charger.
From what you wrote, the charging of the batteries at high rates, creating heat is what kills the cells? Same as blasting a regular car battery with a quick charge deal, boils the water out of them type situation.
Not my wheelhouse, read about the heat management features built into the cars in later generations
