Amino-Rich Polybenzimidazole-Mediated Interfacial Engineering in OPBI/Halloysite Nanotube Composite Separators for...

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-NH₂-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-NH₂-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 LiFePO₄ 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.