Sulfonated fluorinated multi-block copolymer hybrid containing sulfonated(poly ether ether ketone) and graphene oxide: A ternary hybrid membrane architecture for electrolyte applications in proton exchange membrane fuel cells

A ternary hybrid membrane architecture consisting of sulfonated fluorinated multi-block copolymer （SFMC）, sulfonated （poly ether ether ketone） （SPEEK） and I or 5 wt% graphene oxide （GO） was fabricated through a facile solution casting approach. The simple, but effective monomer sulfonation was performed for SFMC to create compact and rigid hydrophobic backbone structures, while conventional random sulfonation was carried-out for SPEEK. Hydrophilic-hydrophobic-hydrophilic structure of SFMC enhances the compatibility with SPEEK and GO and allows for an unprecedented approach to alter me- chanical strength and proton conductivity of ternary hybrid membrane, as verified from universal test machine （UTM） curves and alternating current （AC） impedance plots. The impact of GO integration on the morphology and roughness of hybrid membrane was scrutinized using field emission scanning electron microscope （FE-SEM） and atomic force microscope （AFM）. Ternary hybrid showed uniform intercalation of GO nanosheets throughout the entire surface of membrane with an increased surface roughness of 8.91 nm. The constructed ternary hybrid membrane revealed excellent water absorption, ion exchange capacity and gas barrier properties, while retaining reasonable dimensional stability. The well-optimized ternary hybrid membrane containing 5 wt% GO revealed a maximum proton conductivity of 111.9 mS/cm, which is higher by a factor of two-fold with respect to that of bare SFMC membrane. The maximum PEMFC power density of 528.07mW/cm2 was yielded by ternary hybrid membrane at a load current density of 1321.1 mA/cm2 when operating the cell at 70 ℃ under 100% relative humidity （RH）. In comparison, a maximum power density of only 182.06 mW/cm2 was exhibited by the bare SFMC membrane at a load current density of 455.56 mA/cm2 under same operating conditions.

Synthesis, Self-assembly and pH Sensitivity of a Novel Fluorinated Triphilic Block Copolymer

A novel fluorinated triblock copolymer incorporating 2-ethylhexyl methacrylate （EHMA）, tert-butyl methacrylate （tBMA） and 1H,1H,2H,2H-perfluorodecyl acrylate （FA） （PEHMA-b-PtBMA-b-PFA） was first synthesized using three successive reversible addition fragmentation chain transfer （RAFT） polymerization and the subsequent hydrolyzing at acidic condition. The as-fabricated triblock copolymer exhibited an interesting morphology evolution from the multi-compartment rod-like structure to spherical structure along with the addition of a selective solution. At the same time, a visible phase separation domain could be seen in the core area due to the existence of fluorocarbon segments. Furthermore, the self- assembly behavior of the triphilic copolymer at different pH was also verified by transmission electron microscopy, as well as the dynamic light scattering. These stimuli-responsive multi-compartment nanostructures may have potential applications in drug delivery.

Designing weakly and strongly solvating polymer electrolytes:Systematically boosting high-voltage lithium metal batteries

Practical high-voltage lithium metal batteries hold promise for high energy density applications,but face stability challenges in electrolytes for both 4 V-class cathodes and lithium anode.To address this,we delve into the positive impacts of two crucial moieties in electrolyte chemistry:fluorine atom(-F)and cyano group(-CN)on the electrochemical performance of polyether electrolytes and lithium metal batteries.Cyano-bearing polyether electrolytes possess strong solvation,accelerating Li^(+)desolvation with minimal SEI impact.Fluorinated polyether electrolytes possess weak solvation,and stabilize the lithium anode via preferential decomposition of F-segment,exhibiting nearly 6000-h stable cycling of lithium symmetric cell.Furthermore,the electron-withdrawing prop-erties of-F and-CN groups significantly bolster the high-voltage tolerance of copolymer electrolyte,extending its operational range up to 5 V.This advance-ment enables the development of 4 V-class lithium metal batteries compatible with various cathodes,including 4.45 V LiCoO_(2),4.5 V LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),and 4.2 V LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2).These findings provide insights into design prin-ciples centered around polymer components for high-performance polymer electrolytes.