the difference between 600 cycles (best 18650) and 4000 cycles is night and day. There's already Lithium Phosphate that is warranted for 6000-8000 cycles. That's 19 years. With 600 cycles your battery will hit the landfield in 2 years. A Lithium Phosphate battery will last 19 years before it has to go to the landfield. Nobody takes the environmental cost in consideration until you take away the subsidies and look at the real numbers.