Development Status and Prospect of Lightweight and Multifunctional Integration of Electric Vehicle Power Battery System

The critical transition toward electrification in the global automotive industry faces a core triangular challenge of range, safety, and cost. These three factors mutually constrain each other, forming the primary bottleneck for widespread adoption of electric vehicles. Extending driving range typically requires increasing battery capacity or enhancing energy density, but this often leads to higher manufacturing costs. Simultaneously, increased weight and more complex thermal management demands may compromise structural safety. Conversely, cost-control measures may involve using lower-grade materials or simplifying structural designs, potentially resulting in inadequate mechanical protection and thermal stability risks. Against this backdrop, innovation within the powertrain ecosystem has increasingly focused on a critical yet historically under-optimized component: the battery enclosure or pack casing. As a pivotal element of solutions, innovation in power battery enclosures has evolved from mere “lightweighting” toward systemic innovation characterized by “material-structure-function integration.” This shift reflects an industry consensus: solving the trade-off triangle requires holistic optimization rather than isolated parameter adjustments. This paper critically examines the evolutionary path of material systems used in power battery enclosures—covering high-strength steel, aluminum alloys, and advanced composites, and reveals inherent trade-offs across key performance dimensions for each material category. These include mechanical properties (yield strength, tensile strength, elongation), weight reduction potential (measured by specific strength and weight reduction efficiency), thermal management capability (thermal conductivity and heat dissipation efficiency), and economic viability (raw material costs and manufacturing complexity). For instance, while aluminum alloys offer an excellent balance between weight reduction and thermal conductivity, they fall short in stiffness and lifecycle cost control compared to certain advanced steels. Composites, while unmatched in specific strength and design freedom, face challenges in recyclability, repairability, and high raw material and processing costs. Consequently, we focus on how cutting-edge strategies—such as multi-material hybrid design, biomimetic structural optimization, and smart material integration—push the performance boundaries of traditional material systems. Multi-material fusion design emerges as a dominant concept, synergistically combining materials—such as pairing aluminum's thermal management capabilities with steel's ultra-high strength in critical collision zones, or integrating localized composite reinforcements. This approach necessitates complex joining technology engineering (e.g., adhesive bonding, bonded-riveted hybrid joints, and solid-state joining techniques). Concurrently, biomimetic structural optimization—topological optimization inspired by natural principles like skeletal structures and honeycombs—enables the creation of battery enclosures with exceptional stiffness-to-weight ratios and physical properties. Furthermore, this paper explores the integration of smart materials and embedded sensors. This includes self-healing polymers to mitigate microcrack propagation, alongside sensors for real-time, in-situ monitoring of electrical properties (e.g., resistance) that adaptively transform the battery casing into an active diagnostic entity. Finally, adopting a forward-looking perspective, this paper outlines the developmental paradigm for next-generation power battery systems: achieving intelligent, sustainable battery enclosures that integrate active safety, thermal management, and condition monitoring through material-structure co-design driven by digital twin technology. This holistic vision integrates cyber-physical design tools with advanced manufacturing, providing both theoretical guidance and an engineering blueprint for the technological breakthroughs required to achieve the widespread adoption of electric vehicles by 2030 and beyond—making them truly safe, economical, and accessible.