If you continue to cycle the batteries as deeply as you were in the car this might be true but if you're willing to charge and discharge slower as well as cycle

If you continue to cycle the batteries as deeply as you were in the car this might be true but if you're willing to charge and discharge slower as well as cycle shallower the gain in life for a Li-ion battery is quite remarkable. Obviously you need more batteries but in general energy storage is just less harsh to batteries than use in cars.