I'm no expert, but everything I have seen, says that the problem of fast/rapid charging causing heat that kills batteries is over stated, and might actually be balanced out by other factors. All charging stresses the battery, and getting it off the charger quicker might actually be better than slow charging for longer (maybe like pulling off a bandage).
Nearly everything I have read is that any harm that might come from rapid/fast/quick charging a battery in a modern cell phone is negligible, and unlikely to ever be noticeable. One article suggested that you might drop to 80% max battery capacity 1 to 2 days faster than without the faster charging.