Engineering practical lithium-sulfur batteries: from materials and cell design to advanced diagnostics, standardization, and commercial deployment

Lithium-sulfur (Li-S) batteries are emerging as a promising next-generation battery with high theoretical and practical capacity. Polysulfide dissolution and shuttling, volume expansion, electrolyte consumption, lithium-metal degradation, and poor structural and interfacial stability limit their practical application. Currently, the technology remains at the laboratory level (coin cell) and must be scaled to commercial systems (pouch cells and battery packs) to enable applications in high-energy grid and aviation. This review mainly focuses on engineering practical cell-level systems, including the development of sulfur hosts, catalytic and conductive architectures, binders, separators, electrolytes, lithium-metal interfaces, and advanced cell designs to achieve high energy density. Advanced diagnostics, including post-mortem characterization, electrochemical analysis, and failure-mode identification, are further highlighted as essential tools for establishing reliable structure-property-performance relationships. In addition, the review addresses the need for standardized testing protocols and consistent reporting of practical Li-S metrics to enable meaningful comparison across studies. Finally, challenges associated with electrode manufacturing, pouch-cell scaling, safety, reproducibility, cost, supply chains, recycling, and commercialization are evaluated. By integrating materials engineering, cell design, diagnostics, standardization, and manufacturing considerations, this review outlines a pathway toward high-energy, durable, reproducible, and commercially deployable Li-S battery systems.