NOVELTY - An electromechanical battery comprises a composite rotor enclosed in a housing around a central core which is fixedly disposed in the housing and which has an internal raceway structure; and at least one set of permanent magnet arrays on the internal raceway and disposed between the composite rotor and the central core.    USE - As electromechanical battery.    ADVANTAGE - The electromechanical battery does not require active bearings. It has a composite rim which is capable of higher speeds and which is able to withstand the resulting higher forces. The battery has a passive magnetic bearing to facilitate the high speeds necessary to obtain the capacity and efficiencies desired.    DETAILED DESCRIPTION - An electromechanical battery comprises a housing (32). A central core (46) fixed in the housing has an internal raceway structure. A composite rotor (34) enclosed in the housing around the central core is configured to spin about its vertical axis in the housing. At least one set of permanent magnet arrays (38, 40, 42) is on the internal raceway (48) and between the composite rotor and the central core. A power input stores electrical power to the electromechanical battery. A power output retrieves at least a portion of the stored electrical power.    INDEPENDENT CLAIMS are also included for:    (A) a composite flywheel rim comprising hoop-wound filaments bound in an epoxy matrix forming a composite core; and a first layer of continuous composite filament wound in a first continuous filament spiral-wound pattern around the composite core; and    (B) a passive magnetic bearing comprising closely spaced closed-circuit conductive coils wrapped around a core of non-conductive material; and set(s) of permanent magnet arrays on a base structure to magnetically interact with the conductive coils when the coils pass by the magnet arrays to levitate an object connected to the conductive coils.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional side view of an electromechanical battery of the invention.    Housing (32)    Rotor (34)    Set of permanent magnet arrays (38, 40, 42)    Core (46)    Internal raceway (48)