Compressed air has volumetric energy density similar to lead acid (about half lithium ion) but extremely high power density. Energy density by weight is dependent on scale - bigger is better - because the weight scales as the surface area of the container while the energy scales with volume. But
If you are looking for a power boost on take off, compressed air is totally viable. Doubly so because it would naturally drive a propeller with an air motor which is more efficient at low speeds. Fix the expansion cooling by burning a bit of fuel in the expansion stream.
I won't want to be near a high pressure tank like that if it ruptured though! Maybe its a system that works better for cargo than human transport.