An effective dual-channel strategy for preparation of polybenzimidazole separator for advanced-safety and high-performance lithium-ion batteries

Polybenzimidazole Composite Separators Engineered from MOFs-HNTs Composites Applicated in Lithium-Ion Batteries

Incorporating inorganic nanostructured materials into polymeric separators for lithium-ion batteries (LIBs) enhances properties such as ionic conductivity, electrolyte wettability, and thermal resistance. However, poor interfacial compatibility between inorganic materials and the polymeric matrix remains a significant challenge. In this study, Zr-based UiO-66 metal-organic frameworks (MOFs) is employed as an interfacial binder between halloysite nanotubes (HNTs) and a poly-(arylene ether benzimidazole) (OPBI) matrix, preparing porous separators using the non-solvent phase separation (NIPS) method. The UiO-66 MOFs promote strong adhesion of HNTs to the OPBI chains, creating a more cohesive inorganic-organic system, as confirmed by molecular dynamics (MD) simulations of binding energy. The resulting OPBI@M-H10 composite separator exhibits high porosity (80%), an electrolyte absorption capacity of 377%, and an ionic conductivity of 1.59 mS·cm⁻¹. Furthermore, LiFePO4 half-cells assembled with this composite separator show a discharge capacity of 161 mAh·g⁻¹ and a retention rate of 97.96% after 200 charge-discharge cycles. The separator also demonstrates excellent electrode stability in the plating/stripping test of Li symmetric cells, lasting up to 1600 hours and effectively inhibiting dendrite growth on the Li anode. This approach provides a promising solution for high-performance LIBs separators and paves the way for advancements in LIBs technology and energy storage applications.

Highly Stretchable Polyurethane Porous Membranes with Adjustable Morphology for Advanced Lithium Metal Batteries

A highly flexible, tunable morphology membrane with excellent thermal stability and ionic conductivity can endow lithium metal batteries with high power density and reduced dendrite growth. Herein, a porous Polyurethane (PU) membrane with an adjustable morphology was prepared by a simple nonsolvent-induced phase separation technique. The precise control of the final morphology of PU membranes can be achieved through appropriate selection of a nonsolvent, resulting a range of pore structures that vary from finger-like voids to sponge-like pores. The implementation of combinatorial DFT and experimental analysis has revealed that spongy PU porous membranes, especially PU-EtOH, show superior electrolyte wettability (472%), high porosity (75%), good mechanical flexibility, robust thermal dimensional stability (above 170 °C), and elevated ionic conductivity (1.38 mS cm-1) in comparison to the polypropylene (PP) separator. The use of PU-EtOH in Li//Li symmetric cell results in a prolonged lifespan of 800 h, surpasing the longevity of PU or PP cells. Moreover, when subjected to a high rate of 5 C, the LiFePO4/Li half-cell with a PU-EtOH porous membrane displayed better cycling performance (115.4 mAh g-1) compared to the PP separator (104.4 mAh g-1). Finally, the prepared PU porous membrane exhibits significant potential for improving the efficiency and safety of LMBs.

Microfiber/Nanofiber/Attapulgite Multilayer Separator with a Pore-Size Gradient for High-Performance and Safe Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have an extremely diverse application nowadays as an environmentally friendly and renewable new energy storage technology. The porous structure of the separator, one essential component of LIBs, provides an ion transport channel for the migration of ions and directly affects the overall performance of the battery. In this work, we fabricated a composite separator (GOP-PH-ATP) via simply laminating an electrospun polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) nanofibrous membrane coated with attapulgite (ATP) nanoparticles onto a PP nonwoven microfibrous fabric, which exhibits a unique porous structure with a pore-size gradient along the thickness direction that ranges from tens of microns to hundreds of nanometers. As a result, besides the enhanced thermal stability given by the chosen materials, the GOP-PH-ATP separator was endowed with a superhigh porosity of ~95%, strong affinity with electrolyte, and great electrolyte uptake of ~760%, thus effectively enabling an ionic conductivity of 2.38 mS cm-1 and a lithium-ion transference number of 0.62. Furthermore, the cell with the GOP-PH-ATP separator shows an excellent cycling performance with a capacity retention of 91.2% after 150 cycles at 1 C, suggesting that the composite separator with a pore-size gradient structure has great potential to be applied in LIBs.

Effects of the Separator MOF-Al2O3 Coating on Battery Rate Performance and Solid-Electrolyte Interphase Formation

Metal organic frameworks (MOFs) have unique advantages in optimizing the ionic conductivity of battery separators because of their rich cavity structure and highly ordered and connected pores. In this study, we used a hydrothermal method to synthesize a functional material, Ag-MOF crystal, as a separator coating content, and then studied the properties and application effect of the MOF-Al₂O₃-blended coating applying to a polyethylene (PE) separator (MOF_xAl_1-x/PE). Results show that MOF_0.08Al_0.92/PE (MOF/Al₂O₃ = 0.08:0.92) used in NCM811||Li cells significantly not only improves the fast charge-discharge performance of the cells but also inhibits the growth of lithium dendrites during long-term charge-discharge cycling; the Li⁺ transference number (t_Li⁺) of the MOF_0.08Al_0.92/PE composite separator is 0.61; the Li||separator||Li half-cell circulates stably for 1000 h at varying current density from 0.5 to 10 mA cm^-2 and only produces low overpotentials, indicating that MOF_0.08Al_0.92 stabilizes lithium. The initial capacity of the NCM811||Li cell using the MOF_0.08Al_0.92/PE separator is 165.0 mA h g^-1, its capacity retention is 70.67% after 300 cycles at 5 C, and the interface resistance of the cells only increases from 13.8 to 31.5 Ω, whereas the capacity retention of Al₂O₃/PE separator batteries is only 40.41% (62.2 mA h g^-1) under the same conditions. During the charge-discharge cycling, the MOF-Al₂O₃ coating induces the lithium anode to quickly form a stable and dense solid-electrolyte interphase layer, promotes the uniform deposition of Li⁺, and inhibits the growth of lithium dendrites as well.

Magnetic solid-phase extraction based on zirconium-based metal-organic frameworks for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices

A novel multi-residue method, magnetic solid-phase extraction combined with LC-MS/MS, was proposed for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices. Fe₃O₄@C@UiO-66 was firstly used to extract and enrich pesticides, showing excellent adsorption capacity, which was proved by adsorption kinetic and thermodynamic experiments. Multiple extraction parameters were optimized by Plackett-Burman and Box-Behnken design. Under optimized conditions, good linearity (1.0-200 ng L^-1, R² ≥ 0.9953) for all analytes, detection limits (0.10 to 0.35 ng L^-1), quantitation limits (0.35 to 1.00 ng L^-1), recoveries (83.68-95.99%), and precision (intra-day RSD ≤ 7.06%, inter-day RSD ≤ 9.40%) were obtained, meeting the requirements of pesticides residues analysis. It is worth mentioning that eight chiral pesticides can be separated quickly within 19 min. The above results indicate that the proposed method with satisfactory sensitivity and accuracy has the potential for routine analysis of chiral pesticide residues in aqueous samples.