Is there any specific technical requirement for LiIon-batteries to be used onboard the dreamliner in any case? Anything that technically prevents other battery types from being used? Not speaking about time, cost and weight but functional hard needs. Let them be heavier and bulkier but that can't be the reason to not consider NiCads?
Yes. The answer is hidden somewhere in this long thread - the discharge rate, which is needed for the electric brakes, and for APU start.
quoting Mike Sinnet, VP of Engineering and chief project engineer for the 787:
"The driving factor in our design was really the ability of the battery to discharge a large amount of energy in a very short period of time. And this was required for two different functions at an airplane level.
One was for starting the auxiliary power unit and the other was for being able to apply braking to the airplane in the event that all other power sources in the airplane were lost. The 787 braking system is an electrical braking system. It uses electric power to stop the airplane. And we need to be able to stop the airplane, perform a rejected take off on purely battery power without any other power source at all. So those two things, electric braking on the main battery, APU start on the APU battery. Those are the two things that drove us to considering lithium ion batteries as the best power source for batteries in the design of the 787."
Boeing set up a more detailed website about the 787 here, which explain the systems "in laymans's terms":
787 Electrical System - Boeing 787 Updates
Batteries and Advanced Airplanes - Boeing 787 Updates
Are there any other applications of the LVP65 cell on commercial aircraft or is this new territory for the manufacturer?
None on commercial aircraft.
Boeing has anticipated this question...and proactively mentions that li-ion batteries (but not necessarily that cell) are used in (aero)space engineering, the Boeing 702 communications satellite, and the Mars Rover
