I know, how about a chemistry that will eat away at your aircraft should the case split, produces combustible gasses when charging and discharging, is loaded with toxic materials, can have internal shorts that cause cells to fail, do not like cold weather, will go flat all on their own in a couple of months, can boil dry if overcharged, and will fail completely if discharged to lower than 50-60% of their capacity repeatedly? Sound familiar???
We are used to dealing with lead acid batteries and have come to accept their limitations and safety issues.
With LiFePO batteries we have a safer solution. As stated they are disposable without causing environmental hazard, their electrolyte is stable and non toxic and will not eat through your metalwork, they release no combustible gasses while charging and discharging, are relatively immune from the low temperature issues, due to their low internal resistance heat up less than other types of batteries for the same load applied, and have a depth of discharge down to 20% before needing to be recharged allowing a safety margin for "engine out/alternator out" gliding with all the fast glass panels people have these days, AND THEY WILL NOT SUSTAIN A FIRE under any circumstances.
Just because you are not familiar with them, does not mean they are a bad idea.
As a side note, most of you are sitting with a Li ION battery inches from your crown jewels as we speak......but you have come to accept that as "normal". Would you really go digging around in your pocket looking for a burning lump of lithium quickly enough to prevent injury?