vtt said:
how far do you think NiMh will go in terms of capacity ?
i'm guessing that AA's will top at 3200-3500 mha and AAA's will top at 1300-1500 mha.
i do however think that when they get to their capacity limit they will still improve on faster charge rate , lower self discharge and maybe a longer life cycle.
what do you think ?
I'd probably say the limit is closer to the low end of your range than the high one. Note that we had 2500s well over a year ago. Now we're only up to 2700. Progress used to be much faster which tells me we're getting close to theoretical limits. I do agree that charge rate, self discharge, and perhaps number of cycles will all improve greatly.
On another note, eventually we'll certainly have AAs and AAAs in capacities far more than you mentioned but they won't be NiMH. My money is on supercapacitors for the long term. Exotic materials with high surface area relative to volume such as aerogels combined with other exotic materials with very high dielectric constants might mean AAs with capacities an order of magnitude greater than today. The potential market for cells with this kind of power density is huge. You could make EVs with 1500 to 2000 mile ranges, for example, or store solar power for night use. Best of all, supercapacitors are good for hundreds of thousands of cycles, and the charge rate is limited mainly by the internal resistance plus the power the charging system is capable of delivering.
