Airbus has decided to revert to tried-and-true nickel-cadmium batteries in their new A350 aircraft (currently in ground testing).
The advantage of lithium based batteries (Li-ion, Li-Po, etc.) is how much smaller and lighter you can make them for a given capacity. Smaller and lighter is great for an aircraft. If Boeing can make lithium-ion batteries work then it’ll be a huge advantage for them.
On the other hand, lithium based batteries also tend to be unstable at times. I’ve had a lithium battery swell/deform and go bad on a laptop. I’m also into RC cars and there are all sorts of horror stories with people using Li-Po batteries.
I wonder if it wouldn’t be better/quicker for Boeing to swap in a known/approved nickel-cadmium system to get the Dreamliner back in the skies. They could work out the kinks in the lithium ion system and retrofit later on. If they don’t get these planes back in the sky soon the losses are going to add up fast.