Polypyrrole as the MOFs/polymer interfacial binder applied in mixed matrix porous separator for high temperature safe lithium-ion batteries

Cu-MOFs nanosheets were synthesized and subsequently post-functionalized with polypyrrole to improve their dispersibility and interfacial binding affinity. These functionalized nanosheets were then incorporated into OPBI to prepare mixed-matrix porous separators. The resulting highly porous and mass-transportive separators exhibited excellent cycling stability for Lithium-ion batteries. • The polymerization of PPy on Cu-MOFs nanosheets enhanced their dispersibility. • PPy acted as an interfacial binder i.e., homogenously adhered the MOFs to OPBI chains. • PPy@Cu-MOFs improved the porosity, wettability and conductivity of the OPBI-based MMPS. • PPy@Cu-MOFs MMPS exhibited more mass transportation (Li + flux) • This combination inhibited Li dendrite formation, resulting in long cycling stability for LIBs. Uniform distribution of two-dimensional (2D) metal organic frameworks (MOFs) in polymer composites is crucial for fabricating mixed matrix porous separators (MMPS) for metal-ion (M + ) batteries (MIBs). However, effectively incorporating 2D MOFs into mechanically robust and highly transportive MMPS, without agglomeration and leaching, has been challenging. Herein, we report the post-polymerization of polypyrrole (PPy) on 2D Cu-MOFs nanosheets, and their uniform distribution in the poly-(arylene ether benzimidazole) (OPBI) to prepare highly porous and mass transportive MMPS using non-solvent induced phase separation (NIPS) method for lithium ion (Li + ) batteries (LIBs) applications. The polymerization of PPy not only improved the dispersibility of the Cu-MOFs nanosheets, but also acted as an interfacial binder, ensuring compatibility between the MOFs and OPBI chains. The PPy@Cu-MOFs nanosheets increased the pore size and porosity of the OPBI-based MMPS, creating wider and more uniform cross-sectional channels, thereby enhancing Li + flux between the anode and cathode during battery charge/discharge cycles. The thermally stable, electrolyte-affinitive, and lithophilic PPy@Cu-MOFs/OPBI MMPS, when assembled in LIBs, achieved a discharge capacity of 150.2 mAh· g −1 with sustained performance over 200 cycles, showing no capacity fading even at elevated temperature. This work provides new insights into polymerizing conjugated polymer on 2D-MOFs nanosheets for improved dispersibility and uniform distribution, enabling the design of high-performance, mass transportive MMPS for safe LIBs application to meet current green energy demands.