Polyimide-driven innovations as "inert" components in high-performance lithium-ion batteries

The rapid proliferation of lithium-ion batteries (LIBs) across portable electronics and electrified transportation systems has propelled unprecedented requirements for high energy density, prolonged cycle life, and improved safety protocols. Polyimides (PIs), attributed to the excellent thermal stability, mechanical robustness, chemical stability, and flame retardant properties, have been widely researched as "inert" materials to address critical challenges in advancing LIBs. Herein, this review provides design principles for employing PIs' inherent characteristics to develop next-generation high-performance LIBs with balanced energy density, rate capability, and operational reliability. PI-based "inert" components, including PI-based separators, solid-state electrolytes, protective layers, and binders, overcome the limitations of conventional materials by enhancing the safety of liquid batteries, reinforcing the mechanical properties, stabilizing the electrolyte/electrode interface, and maintaining the electrode integrity. Key challenges and optimization pathways for practical implementation are discussed and proposed. Finally, prospective research directions of PIs in LIBs are also outlined to provide critical orientation for research fields.