The amount of time it takes to charge a battery is inversely proportional to the current - there is nothing surprising about the fact that using more current charges a battery in less time.
What is surprising about this research is that one small process change (doing that initial charge with a high current instead of a low one) resulted in a 50% increase in the total lifetime of the battery. That's the part that feels like "free money" in that, if accurate, this means battery producers could produce batteries with much longer lifespans without any fundamental change to their battery architecture or chemistry.
