Like 2000mhz? Or more piwerful one?
I think you mean mAh, maybe your autocorrect has gone haywire the capacity of a battery is measured in this unit... Milliampere hours. This is the amount of energy that the battery will allow to let 1 amp of current to flow in one hour. A mAh is NOT a measurement of energy, is a measurement of the speed of the flow of energy... Therefore it's nothing to do with the "power" of the battery. So to answer your question, a 2000mAh battery is absolutely fine as long as its from a reputable manufacturer such as Ankers or Mugen; DO NOT buy any higher capacity batteries with no brand name off eBay. If you're having trouble figuring out if the battery you want is safe then just post the link here and I'll check it out for you . another option would be to get a battery from you phone manufacturer which is higher capacity, for example many HTC phones use the same size battery but some are different capacities... Yeah beats me too
This is incorrect. Using a battery of a different voltage would be damaging, but I expect all phone batteries are similar, if not the same, voltage. A battery which provides too much current may be damaging too. But a higher capacity battery is perfectly safe provided the potential difference and current are the same as usual.