Like all lithium batteries, they can only recharge a certain amount before the battery expires. Nissan leaf is usually a private owned car so may last a good few year in low mileage use.
The boy sorting some out in Exeter found some had a 10 mile range when traded in. There was a dealer in Exeter selling a batch he had bought very cheaply but since that batch, has now resorted back to selling petrol cars. No history of what became of them.