Preparation And Properties Of Sulfonated Poly(aryl Ether Sulfone)/inorganic Nanoparticles Composite Proton Exchange Membranes

Proton exchange membrane（PEM）is one of the core of the fuel cell,and its electrical conductivity,mechanical properties,and physical and chemical properties of fuel cells will directly affect the actual operation of fuel cells.In this paper,carboxyl-modified diamond was used to solve the problems of poor hydrophilicity of ND and poor compatibility with SPAES.Then,sulfonated diamond was used to solve the problem of low IEC of carboxyl-diamond composite films.The conductivity and battery performance are improved but stability decrease is produced.Therefore,the sulfonic acid-modified onion carbon was selected to improve the chemical stability and electrical conductivity of the membrane.Firstly,nano-diamonds were oxidized by concentrated sulfuric acid and concentrated nitric acid to prepare carboxyl-modified diamond（ND-COOH）.Blended with SPAES,a series of SPAES/ND-COOH nanocomposite membranes（1.66-1.7mmol/g）were synthesized by the method of solution casting.The SPAES/ND-COOH membrane showed good water absorption swelling rate and excellent proton conductivity.The water absorption rate at 80°C were 50.5-64.4%,and the swelling rate were 14-18.3%.The proton conductivity of the SPAES/ND-COOH-3 membrane in 80℃water reached 149.8m S/cm.Under the conditions of 80°C and 100RH%,the maximum power density of the fuel cell with SPAES/ND-COOH-3 membrane reached 461m W/cm².Secondly,oxygen-containing functional groups are introduced on the surface of nano-diamond（ND）by the oxidation of edge defect carbons with KMn O₄and concentrated H₂SO₄to get the oxide diamond（OND）.Under strong alkali conditions,ONDs are reacted with 1,4-butylene sulfonate lactone to get sulfonic acid alkyl nano-diamond（SND）,and blend with SPAES,and synthesize SPAES-SND composite membranes（1.33-1.46mmol/g）by solution casting method.The results showed that the prepared membranes had greatly improved water absorption and swelling,and exhibited higher proton conductivity.The overall performance of the SPAES-SND-0.5 membrane was better,with a proton conductivity of 166m S/cm at 80°C.At 80°C and 100%RH,the maximum power density of SPAES-SND-0.5 film reached 491 m W/cm²,which was 42.3%higher than that of SPAES film.Finally,preparation of nano-onion carbon（CNO）by thermal annealing method using ND as raw material.After being oxidized by potassium permanganate,CNO reacted with1,4-butane sultone in the presence of Na OH to successfully prepare sulfonate butyl modified onion carbon（SCNO）.SPAES-SCNO composite membranes（1.62-1.69mmol/g）was prepared by casting and blending with SPAES.SPAES-SCNO film showed good elongation at break and oxidation resistance.Among them,the elongation at break of SPAES-SCNO-2 film was 21%,and that of SPAES-SCNO-1 film was in Fenton reagent(3wt%H₂O₂+2mg/LFe²⁺).After treatment,the weight loss rate of the membrane was 8.1%.The maximum power density of the hydrogen-oxygen fuel cell with the SPAES-SCNO-1membrane at 80°C and 100%RH reached 426 m W/cm².