A vehicle-battery system including a battery cell and a micro heat exchanger. The micro heat exchanger includes at least one fluid tube positioned in direct contact with the battery cell. The fluid tube comprises a heat-transfer tube section positioned between a fluid tube entrance and exit and in direct contact with the battery cell. The fluid tube is configured to receive a heat-transfer fluid, such a nanofluid, and channel the heat-transfer fluid through the heat-transfer tube section, to the fluid tube exit. The heat-transfer fluid is configured to cool or heat the battery cell when, in operation of the vehicle-battery system, the heat-transfer fluid is channeled through the heat-transfer tube section. The technology in various embodiments also includes a fluid modification device and a computerized controller for controlling the fluid modification device or other operations of the system such as pumping of the heat-transfer fluid.