Abstract: Flywheel battery systems having improved energy density are provided. Such systems preferably have an inner rotor mounted coaxially and substantially cylindrically within an outer containment rotor. The outer rotor counter-rotate relative to said inner rotor so as to manage the net gyroscopic force generated by the flywheel system. The outer rotor has a greater relative inertia as compared to said inner rotor and therefore can be rotated at a relatively lower rotational velocity to balance the gyroscopic forces generated by the rotation of the inner rotor. The relative rotational velocities of the inner and outer rotor are maintained by a combined mechanical and magnetic drive/suspension system.