Interesting is the Battery 500 project where the Lithium Air battery is aimed at. Li air is associated with a lot of hurdles, but if these can be overcome using modern material science (nano particles, graphene, etc.) it might work.
Also interesting in this regard is the Alum-air battery. Although not rechargeable currently, it holds a good promise. It can do 1300 Wh/kg as compared with current Li technology 110 Wh/kg. So this will allow good range for the Craft ultimately.
On safety area there is a lot of work to be done. Funny that NASA for the one of its space crafts developed special air bags, and recently started to use the idea for helicopters. Think this shows that there is a huge area of innovations that we will see in the air bags development for many applications: skying, motorbikes, cars outside, drones, etc.. see this link.
So there is indeed a lot of scope for such device to be used for the humming man craft. Interesting too is a type of helium emergency lifter. It would need a ca 6.6 m diameter balloon to be conceived as a huge air bag of 6.6 meter diameter. Can it be done? Again let's discuss it!
Fresh idea's, let's talk,