This paper introduces a module-integrated distributed battery energy storage and management system without the need for additional battery equalizers and centralized converter interface. This is achieved by integrating power electronics onto battery cells as an integrated module. Compared with the conventional centralized battery system, the modular design brings several advantages such as reduced power rating and voltage stress of power electronics, no extra equalizers or centralized converters, active thermal distribution control ability, enhanced safety and reliability, etc. The battery system can now be built by simply attaching integrated modules together. The integrated module is implemented by a synchronous bidirectional dc/dc converter with digital control techniques. The design considerations and control strategy of the system are discussed. A prototype is built that the power electronics are integrated onto the battery cell. Experimental results of a three-module system verified that the module-integrated distributed system provides satisfied functional performance without extra equalizers, centralized charger, or bidirectional dc/dc converter.