There are 3 main Lithium based battery solutions currently avail:
Li-ion = Lithium Ion - been around longest and widest deployed (avail since mid 1990's at least) - Good density; somewhat unstable (can catch fire); moderate price
Li-Poly = Lithium Polymer - been around since early 2000's - Best density; more unstable; most expensive
LiFePO4 = Lithium Iron Phosphate - been around since early 2010's - Less density; stable; least expensive -> almost all SLA replacement batteries are these - you can typically use SLA chargers to charge and have voltages around same as typical SLA's
Which is your preferred battery for taping?
I would imagine if taping outdoors (festivals, etc) in the sun maybe the most stable batteries are best?
In indoor venues would the most dense battery best?
Also which has the least amount of memory loss over time.