Electrochemical capacitance of CNF–Ti3C2Tx MXene-based composite cryogels in different electrolyte solutions for an eco-friendly supercapacitorKokol, Vanja (Avtor) Lakshmanan, Subramanian (Avtor) Vivod, Vera (Avtor) cellulose nanofibrilsTi3C2Tx MXenefreeze-castingaqueous electrolytesphysico-chemical propertieselectric double layerpseudocapacitanceCellulose nanofibrils (CNFs) are promising materials for flexible and green supercapacitor electrodes, while Ti3C2Tx MXene exhibits high specific capacitance. However, the diffusion limitation of ions and chemical instability in the generally used highly basic (KOH, MXene oxidation) or acidic (H2SO4, CNF degradation) electrolytes limits their performance and durability. Herein, freestanding CNF/MXene cryogel membranes were prepared by deep freeze-casting (at −50 and −80 ◦C), using different weight percentages of components (10, 50, 90), and evaluated for their structural and physico-chemical stability in other less aggressive aqueous electrolyte solutions (Na2/Mg/Mn/K2-SO4, Na2CO3), to examine the influence of the ions transport on their pseudocapacitive properties. While the membrane prepared with 50 wt% (2.5 mg/cm2 ) of MXene loading at −80 ◦C shrank in a basic Na2CO3 electrolyte, the capacitance was performed via the forming of an electroactive layer on its interface, giving it high stability (90% after 3 days of cycling) but lower capacitance (8 F/g at 2 mV/s) than in H2SO4 (25 F/g). On the contrary, slightly acidic electrolytes extended the cations’ transport path due to excessive but still size-limited diffusion of the hydrated ions (SO4 2− > Na+ > Mn2+ > Mg2+) during membrane swelling, which blocked it, reducing the electroactive surface area and lowering conductivities (<3 F/g).MDPI20252025-04-07 11:59:46Članek v reviji92414UDK: 677.46:620.3COBISS_ID: 231603459DOI: 10.3390/gels11040265ISSN pri članku: 2310-2861sl© 2025 by the authors