Next-generation energy storage systems for electric vehicles, aviation and grid-scale applications require batteries with higher safety, longer lifetime and greater adaptability than conventional lithium-ion cells. This demand is driving a transition from passive energy-storage devices towards smart battery systems that can regulate local degradation, perceive hidden internal states and support decision-oriented management. From a materials perspective, this transition relies on two coupled capabilities. The first is autonomous regulation by responsive materials, including self-maintaining electrodes and interfaces, self-adaptive electrolytes and interlayers and self-defensive separators or current collectors that respond to cell-relevant mechanical, thermal, electrochemical or chemical perturbations. The second is battery-integrated perception, in which sensing and transduction materials convert local temperature, strain, pressure, gas, potential, optical or acoustic signatures into readable signals for diagnosis and safety warning. Data-driven and artificial intelligence-assisted methods further enable materials discovery, multimodal-signal interpretation and future battery-management decisions. Ultimately, realizing smart battery systems requires architectures that balance cell compatibility, manufacturability, parasitic mass and volume, sensor integration, lifecycle sustainability and closed-loop operation.