A 3-D “phase change heat exchange” structure and method are used in a rechargeable battery to dissipate heat from surfaces of the battery cells and lower the temperature inside the battery cells. The battery cells are placed inside an enclosure and spaced apart from each other with free spaces in between. A liquid to vapor phase change material (L-V PCM) is provided inside the enclosure. A hydrophilic thin film or wick or fiber structure is provided on the cell surfaces to help form a thin liquid layer of the L-V PCM over cell surfaces. During operation, the L-C PCM is evaporated at the cell surfaces and condenses back to a liquid either on the battery enclosure or in an external heat exchanger, and drips back on top of the cells. The designs extend the battery life and improve the battery performance significantly.