You don't even need to be an expert to poke at why this is extremely implausible.

Think about the materials involved. What material stores all this energy, which one assumes is inert and room-temp? And if it's not inert/room-temp, what material contains the other material?

In each case, how much mass is needed of each - to store, and to contain? Noting also that the more mass you need of the energy-bearing material, the more you will need of the other. Can that mass be compressed into 4 cubic centimeters?

I personally have no idea, but it's sure sounding impossible.