Abstract: The critical transition toward electrification in the global automotive industry faces a triangular challenge of range, safety, and cost. These three factors mutually constrain one another, forming a primary bottleneck to the widespread adoption of electric vehicles. Extending driving range typically requires increasing battery capacity or energy density, which often raises manufacturing costs. Simultaneously, increased weight and more complex thermal management requirements may compromise structural safety. Conversely, cost-control strategies may involve lower-grade materials or simplified structural designs, potentially leading to insufficient mechanical protection and thermal stability risks. Against this backdrop, innovation within the powertrain ecosystem has increasingly focused on a critical yet historically underoptimized component: the battery enclosure or pack casing. As a key enabling element, innovation in power battery enclosures has evolved from simple lightweighting toward systemic approaches characterized by material–structure–function integration. This shift reflects an emerging industry consensus that resolving the trade-off among range, safety, and cost requires holistic optimization rather than isolated parameter improvements. This paper critically examines the evolution of material systems used in power battery enclosures, including high-strength steels, aluminum alloys, and advanced composites, and identifies the inherent trade-offs across key performance dimensions for each material class. These dimensions include mechanical properties (yield strength, tensile strength, and elongation), weight-reduction potential (specific strength and weight-reduction efficiency), thermal management capability (thermal conductivity and heat dissipation efficiency), and economic viability (raw material cost and manufacturing complexity). For example, although aluminum alloys provide an effective balance between weight reduction and thermal conductivity, they exhibit lower stiffness and less favorable life-cycle cost control than certain advanced steels. Composites, while offering superior specific strength and design flexibility, face limitations related to recyclability, repairability, and high material and processing costs. Accordingly, this study examines how advanced strategies—including multi-material hybrid design, biomimetic structural optimization, and smart material integration—extend the performance limits of conventional material systems. Multi-material design has emerged as a dominant approach, enabling synergistic combinations of materials, such as pairing the thermal management advantages of aluminum with the ultra-high strength of steel in critical crash zones or integrating localized composite reinforcements. This approach requires advanced joining technologies, including adhesive bonding, bonded–riveted hybrid joints, and solid-state joining techniques. In parallel, biomimetic structural optimization, including topology optimization inspired by natural structures such as skeletal systems and honeycombs, enables the design of battery enclosures with exceptional stiffness-to-weight ratios and multifunctional properties. Furthermore, this paper investigates the integration of smart materials and embedded sensors, including self-healing polymers to limit microcrack propagation and sensors for real-time in situ monitoring of electrical properties (e.g., resistance), thereby enabling the battery enclosure to function as an active diagnostic component. Finally, from a forward-looking perspective, this paper outlines a development paradigm for next-generation power battery systems focused on intelligent and sustainable battery enclosures that integrate active safety, thermal management, and condition monitoring through material–structure co-design supported by digital twin technology. This holistic vision integrates cyber–physical design tools with advanced manufacturing, providing both theoretical guidance and an engineering framework for the technological advances required to support the widespread adoption of electric vehicles by 2030 and beyond, making them safer, more economical, and more accessible.