Highly porous zeolitic imidazolate framework-8@bacterial cellulose composite separator with enhanced electrolyte absorption capability for lithium-ion batteries

Currently, the commercial polyolefinbased separators suffer from inferior electrolyte absorption capability and poor thermal stability, leading to unsatisfactory electrochemical performance and severe safety hazards for lithium-ion batteries (LIBs). Herein, a high-performance zeolitic imidazolate framework-8@bacterial cellulose (ZIF-8@BC) composite separator was fabricated via in-situ synthesizing ZIF-8 on BC nanofibers followed by filtration process. The ZIF-8 particles served as micro-spacers to prevent the dense packing of BC nanofibers during drying and significantly improved the porosity from 54.6 (pure BC separator) to 73.2% (composite separator). Combining the exceptional electrolyte affinity and well-developed porous structure, the as-prepared ZIF-8@BC composite separator displayed high electrolyte uptake (340.5%) and good electrolyte wettability, which brought about superior ionic conductivity (1.12 mS cm(-1)) compared to commercial polypropylene separator (0.38 mS cm(-1)). These synergistic advantages eventually endowed the battery using ZIF-8@BC separator with excellent rate capability and cycling performance. Furthermore, the ZIF-8@ BC separator showed suitable mechanical strength and outstanding thermal resistance, which ensured higher safety during battery operation. Accordingly, the ZIF-8@BC composite separator is a promising candidate for next-generation LIBs with both enhanced performance and high safety. [GRAPHICS] .

Automated summary

A high-performance ZIF-8@BC composite separator was fabricated by in-situ synthesizing ZIF-8 particles on bacterial cellulose nanofibers. The composite separator showed high electrolyte absorption, improved porosity, and enhanced ionic conductivity compared to commercial polypropylene separator. It also exhibited suitable mechanical strength and outstanding thermal resistance, ensuring higher safety during battery operation. The ZIF-8@BC composite separator is a promising candidate for next-generation LIBs with enhanced performance and high safety.