You are right, most batteries last longer and perform better with gentle charging and discharging cycles. The converse is also true. Constant rapid charging of EV batteries is detrimental to their lifespan and performance. This is often overlooked as one of the costs of an EV. This contributes to the abysmal trade in value of EV’s. When you factor that in to an EV’s expense, It becomes insanely expensive compared to ICE powered vehicles.
I have been playing with salt batteries on a small scale. I am currently moving back off grid and want to build a large six cell salt battery to try and store my power. Even though they take up three times the space as other batteries, they have a huge advantage of endless discharge/recharge cycles without losing efficiency. They can also be made more efficient by adding Hydrogen Peroxide. The only real draw back is the cathodes and anodes are sacrificial and need to be replaced once in awhile as a regular maintenance item. But using graphite anodes greatly helps with this issue.