Amino‐Rich Polybenzimidazole‐Mediated Interfacial Engineering in OPBI/Halloysite Nanotube Composite Separators for Enhanced Lithium‐Ion Battery Performance

Abstract The incompatibility between inorganic and organic materials has significantly hindered the development of high‐temperature lithium‐ion batteries (LIBs) composite separators. In this work, amino‐rich polybenzimidazole (Py‐NH ₂ ‐PBI) is synthesized and chemically coated onto halloysite nanotubes (HNTs). The modified composite (PyPBI@HNTs) nanofillers have been integrated with a polybenzimidazole (OPBI) matrix, resulting in a high‐performance OPBI@Py‐H separator with enhanced inorganic‐organic compatibility. The improved interfacial compatibility strengthens the bonding between the inorganic and organic phases, as confirmed by density functional theory (DFT) calculations. Additionally, the nitrogen‐rich Py‐NH ₂ ‐PBI in the separator enhances electrolyte affinity and provides more transport sites for fast lithium ions (Li ⁺ ) conduction. As a result, compared to the unmodified OPBI@HNTs separator, the OPBI@Py‐H separator exhibits a 30.96% increase in tensile strength (TS) and a 21.82% increase in ionic conductivity (σ). Furthermore, the LiFePO ₄ cells assembled with the OPBI@Py‐H separator demonstrate a high discharge specific capacity of 160.12 mAh g ⁻¹ at 0.5 C. The OPBI@Py‐H separator also shows exceptional inhibition of disordered lithium dendrite growth (3000‐h lithium plating/stripping test), and provides outstanding cycling stability and safety at 90 °C. This work provides a scalable strategy to overcome interfacial incompatibility, advancing the development of high‐safety, high‐energy‐density LIBs.