Study on Modification and Performance of PEMs Based on Sulfonated Poly(Ether Ether Ketone)

Author:Dong Cui Cui

Supervisor:zhou qiong


Degree Year:2018





Sulfonated poly(ether ether ketone)(SPEEK)is one of the most ideal alternatives for Nafion.There are many isolated proton channels in SPEEK membrane that make the proton conductivity is much lower than Nafion.We design and regulate the microstructure of the SPEEK membrane with layered and columnar inorganic nano-filler.The continuous proton channels are introduced into the SPEEK matrix and the discontinuous proton channels are connected.The purpose is to improve the proton conductivity and reduce the methanol permeability of the composite membrane.We install the basic functional group on the layered filler,so that the acid-base pairs could build up between layered filler and SPEEK.Furthor more,the phosphotungstic acid(HPW)is droped to the system and anchored by the alkaline nanosheet.The layered filler cooperate with HPW affect on proton conductivity,stability and DMFCs performance of composite membrane.First,the relationship between the micromorphology of SPEEK with different DS and the water uptake,swelling rate and proton conductivity are investigated,and compared with Nafion.Graphene oxide(GO)was prepared and modified by ethylenediamine(EGO).GO and EGO were doped into SPEEK matrix to construct SPEEK/GO and SPEEK/EGO composite membrane with layered microstructure.The layered structure and acid-base pair have a positive impact on the properties of the composite membrane.The selecvitity of SPEEK/EGO-1.5 composite membrane is 1.4times of SPEEK/GO-1.5 and 1.6 times of SPEEK.Graphite phase g-C3N4 with-NH-and-NH2 is prepared by calcination and ultrasonic peeling method.The g-C3N4 nanosheet and HPW are introduced into SPEEK matrix.Alkaline g-C3N4 forms acid-base pair with the SPEEK matrix to improve conductivity of membrane and form hydrogen bonds with HPW to anchored HPW in composite mebrane without leaking.The conducitivity of SPEEK/HPW/g-C3N4-1.0 increase of 183.5 to249.1 mS cm-1.The weight loss rate decrease from 62.8%to 38.4%.The powder current density is 484.9 mA cm-22 which is 1.2 times of SPEEK and 1.3 times of SPEEK/HPW.TiNFs and TNTs are prepared by calcination electrospinning and hydrothermal method,respectively.The SPEEK/TiNFs and SPEEK/TNTs composite membranes are prepared.It is found that the calcining process is safer than the hydrothermal process.The TiNFs has better dispersion in the matrix and suture the proton channel.The proton conductivity of SPEEK/TNTs-1.0 composite membrane decreased by 10.5%compared with SPEEK at 20℃,while the proton conductivity of SPEEK/TiNFs-1.0 composite membrane increase by 24.9%.HPW was doped into the spinning solution to improve the suture ability of TiNFs,and the TiO2/HPW composite fiber(TiWNFs)with high proton conductivity is prepared.The proton conductivity of the SPEEK/TiWNFs composite membrane is further improved.The proton conductivity of SPEEK/TiWNFs-1.0composite membrane increased by 84.7% compared with SPEEK at 20℃.