Multi-channeled halloysite nanotube-blended polybenzimidazole separators for enhancing lithium-ion battery performance

Abstract

The microscopic transport mode of lithium ions in the separator is crucial for solving the problem of irregular lithium dendrite growth, thereby enhancing the safety of battery operation, and it also has a positive impact on the electrochemical performance of the battery. Furthermore, the heat resistance of the separator is an important indicator for measuring the performance of the separator and the safety of battery usage. In this work, we have introduced sulfonated and lithiated halloysite nanotubes into a high-temperature-resistant OPBI matrix through an easily implementable NIPS, resulting in a high-temperature-resistant separator with multiple lithium-ion micro-transport morphologies. Lithium ions can shuttle through the halloysite nanotube pores, negatively charged sulfonate groups on the surface, and larger finger-like pores formed by NIPS within the separator, creating a high and uniform lithium-ion flux that prevents excessive localized ion flow leading to the aggressive growth of lithium dendrites. According to the characterization data, this separator exhibits relatively satisfactory performance, such as an ionic conductivity of 1.82 mS cm⁻¹, a porosity of 82 %, an electrolyte uptake of 397 %, and no significant physical shrinkage at 200 °C. Additionally, the cells assembled using the OPBI@sHNT-Li20 separator delivers higher discharge capacity (164.92 mAh·g⁻¹), more stable cycle, superior rate performance. So the OPBI@sHNT-Li separator is expected to play an active role in improving the safety and electrochemical performance of lithium-ion batteries.