直接膜沉积法逐层狭缝涂布电解水膜电极：和热转印制备方法的对比A completely slot die coated membrane electrode assembly

Markus Stähler

Andrea Stähler

Fabian Scheepers

Marcelo Carmo

Detlef Stolten

Abstract

This work shows how to manufacturecompletely coated membrane electrode assemblies （CC－MEAs） for PEM waterelectrolysis by only using a slot die． Platinum， Nafion®， and IrO2 dispersionsare successively coated to the respective dried layer． For comparison reasons， MEAs with the same Iridium loading of 2．1mg cm−2 and Platinum loading of 0．4 mg cm−2， assembled with a commercialmembrane of the same 20 μm thickness， were produced via decal method． Differencesin polarization curves are attributed to the lower high frequency resistance ofCC－MEAs determined by impedance spectroscopy． The easy－to－scale CC－MEA methodpresented here offers the advantages ofdirect membrane deposition （DMD） withoutthe challenge of homogenously coating a porous transport layer （PTL）．Therefore， it allows a free choice of different PTLs – regardless if insintered form or as expanded metal． The comparability between the producedCC－MEAs and published DMD results is shown by means of cross－sectional andelectrochemical measurements．

Fig． 1 e Manufacturing process of CC－MEA．  The following parameters were the same for all steps： coating width： 50 mm； thickness  of upstream and downstream lip Lu＝Ld＝1 mm； substrate speed u＝0．3 m／min A1－A3：  Slot die coating of the PTFE substrate with cathode dispersion by means of a  template． A4： Slot die settings： Dosing rate q＝1．5 ml／min， slot width S＝250 um，  coating gap G＝900 um， calculated wet film thickness Hwet＝100 um．

B1－B3： Slot die coating of the cathode  with Nafion® dispersion including a PET frame for mechanical stabilization．  B4： Slot die settings： Dosing rate q ＝2．25 ml／min， slot width S＝250 um，  coating gap G＝350 um， calculated wet film thickness Hwet＝150 um．

C1－C3： Slot die coating of the membrane  with the anode dispersion by means of a template． C4： Slot die settings：  Dosing rate q＝1．31 ml／min， slot width S＝350 um， coating gap G＝300 um，  substrate speed u＝0．3 m／min， calculated wet film thickness Hwet＝87 um．

D1－D3： Hot pressing process at 130 C and  0．5 kN／cm2． D4： Photograph of the CC－MEA stabilized by a 23 um thin PET  frame． Edges of the PET frame are indicated by a dotted line．

Fig． 2 e Representative cross－section  images （resolution： 150 ppi） of a CC－MEA （A and C） and a decal Nafion® HP－MEA  （B and D）． Both membranes show a comparable thickness of （20 ± 2） mm．

Fig． 3 e （A） Polarization curve of a  CC－MEA in comparison to a Nafion® HP－MEA． Anode loading： （2．1 ± 0．05） mg／cm2  Iridium， cathode loading： （0．4 ± 0．02） mg／cm2 Platinum． The cell temperature  was 80 C under ambient pressure． （B） Spectra of the absolute impedance at  1．46 V， 1．50 V and 1．55 V．

Conclusions

This paper presents a slot die based  manufacturing technique that allows the building up of an electrode－membrane electrode  assembly － layer by layer － without the use of a separate membrane． This  method takes advantage of the DMD technology without the requirement of a PTL  coating．

The use of only one tool for the complete  fabrication of an MEA simplifies the production and process scalability． The  CCMEAs produced in this way achieved current densities of 11 A／cm2 at 2 V．

For future studies， the presented  technique offers many possibilities for variations to investigate  correlations in MEAs for PEM water electrolysis． From membrane thickness  adaption and applying additives to the dispersion to reduce hydrogen  permeation， through the application of an MEA with different titanium PTLs，  regardless of whether it is in sintered form or in that of expanded metal，meshes  or felts． In addition to the already existing methods， the technique  presented here will help to further improve MEAs for PEM water electrolyzers and  other electrochemical energy conversion devices in future．

看标题时没太注意不是常规的狭缝涂布。

缺点的是没法做复合膜的膜电极。