Thanks for adding all the battery data to AIDA64 on iOS - being able to see voltage, cycle count and current goes a long way in helping to properly preserve and maintain the battery on my iPhone.
One thing I have always wanted to do is be able to set a maximum charge limit on the battery - as battery endurance is heavily impacted by the maximum charging voltage (in addition to time, charge cycles and temperature), I've always wanted to keep my devices from charging above 4V (around 70% of maximum charge) to help prevent the battery from wearing out too quickly (my iPhone is almost always plugged into a charger as I am 'chained' to my desk most of the day). Charging to 4.3V or even 4.4V on a regular basis is great for getting long single charges each day, but it wears these Li-ion batteries out extremely fast. My iPhone 6s battery has only had 235 cycles but is already at a 13% wear level, and I've only owned it for seven months now.
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
This is a bit of a long shot as this is something Apple should be implementing themselves (but won't), but if you could find a way to limit the maximum charge of an iOS device, that would be fantastic.
(After all, Tesla does this in its electric cars - allows users to specify the maximum charge between 50-100%, so yeah...)