Composite lithium-conductive LATP+PVdF membranes: Development, optimization, and applicability for Li-TEMPO hybrid redox flow batteries

A Complex Investigation of LATP Ceramic Stability and LATP+PVDF Composite Membrane Performance: The Effect of Solvent in Tape-Casting Fabrication

“…The composite membranes were fabricated using a simple tape-casting method ( Figure S2, Supplementary Materials ) close to the previously reported [ 35 ] but with several minor changes (casting temperature, heating bath, drying atmosphere etc.). The component ratios of LATP:PVDF and PVDF:solvent were optimized in our previous publications to achieve the suitable IC/permeability trade-off and for the ease of the casting procedure; the ratios equal 45:55 and 15:85, respectively [ 34 , 35 ].…”

“…The composite membranes were fabricated using a simple tape-casting method ( Figure S2, Supplementary Materials ) close to the previously reported [ 35 ] but with several minor changes (casting temperature, heating bath, drying atmosphere etc.). The component ratios of LATP:PVDF and PVDF:solvent were optimized in our previous publications to achieve the suitable IC/permeability trade-off and for the ease of the casting procedure; the ratios equal 45:55 and 15:85, respectively [ 34 , 35 ]. The as-synthesized ceramic pellets were manually ground in the agate mortar, followed by the intense ball-milling (SPEX 8000, Metuchen, NJ, USA) for 90 min in an agate vial with one milling sphere to achieve the mean particle size of about 1 μm, according to our previous report [ 35 ].…”

“…The component ratios of LATP:PVDF and PVDF:solvent were optimized in our previous publications to achieve the suitable IC/permeability trade-off and for the ease of the casting procedure; the ratios equal 45:55 and 15:85, respectively [ 34 , 35 ]. The as-synthesized ceramic pellets were manually ground in the agate mortar, followed by the intense ball-milling (SPEX 8000, Metuchen, NJ, USA) for 90 min in an agate vial with one milling sphere to achieve the mean particle size of about 1 μm, according to our previous report [ 35 ]. Simultaneously, 0.5 g of PVDF (M w ~534000, Sigma-Aldrich, St. Quentin Fallavier Cedex, France) was dissolved under magnetic stirring (400 rpm) in 3 mL of either DMF (≥99.8%, RusChem, Russia), DMSO (≥99.7%, Acros Organics, Branchburg, NJ, USA), or NMP (≥99.5%, Acros Organics, NJ, USA), all preliminarily dried with 3 Å sieves until c(H 2 O) < 25 ppm.…”

“…From now on, we additionally expected the introduction of the inert matrix to protect the LATP filler from the ambient humidity and preserve its originally high IC. Then, we reported our first version of the tape-casting fabrication route of composite LATP+PVDF membranes [ 34 ] along with their general electrochemical properties and primary performance in organic flow and Li-hybrid cells [ 35 , 36 ]. We showed that the fabricated membranes demonstrated ultimate stability to metallic Li, high IC (3.4 ∙ 10 −4 S cm −1 ), good integrity, but relatively high permeability to (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)—a model redox active compound [ 35 ].…”

“…Then, we reported our first version of the tape-casting fabrication route of composite LATP+PVDF membranes [ 34 ] along with their general electrochemical properties and primary performance in organic flow and Li-hybrid cells [ 35 , 36 ]. We showed that the fabricated membranes demonstrated ultimate stability to metallic Li, high IC (3.4 ∙ 10 −4 S cm −1 ), good integrity, but relatively high permeability to (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)—a model redox active compound [ 35 ]. Based on the results collected, we reasonably expected the membrane’s porosity to be the main reason behind its permeability and cell’s capacity decay.…”