@CuriousVidhi this is a great question for planning the design part.
[justify]I think here we should link the weight as one of the important parameter to decide the material for frame and also need to equally account the strength as per application.[/justify]
[justify]Also batteries should weigh less but capable of delivering more power for longer run.[/justify]
For frame material how about Carbon Fiber?
And for Batteries how about Lithium Polymer Batteries?