system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it that batteries cannot be charged quickly? 

It seems it takes no time at all to drain a battery but to charge it is just the opposite. What gives?
gpt
chem eng here. well recharging a battery is reversing a chemical reaction and the rate at which you can do this is limited by the rate of ion transport to the electrodes. if you go pumping high voltage and current into a system which cannot react fast enough, you will risk decomposing your reagents and damaging the battery. there are different media such as solutions, gels and pastes, each with different properties. a paste may be slow or impossible to recharge but offers the advantage of no spills.