This story in the Union of Concerned Scientist blog discusses a range of issues related to re-using and recycling EV batteries.
I believe that manufacturers should be made legally responsible for ensuring that EV batteries are always re-used or recycled. If re-used, it would be with an obligation that they will eventually be recycled. Done properly, this would largely eliminate wasteful disposal, plus provide a powerful incentive for manufacturers to make EV batteries circular by design.