Introduction

Electrolysers, batteries and fuel cells all require judiciously designed and engineered (nano-) structures in their basic repeated units, on which their macroscopic performance depends critically: electronically-conducting anode (oxidation) | ion-conducting electrolyte | electronically-conducting cathode (reduction), with electron transfer reactions occurring at the interfaces (|). Such reactors need to be developed urgently, e.g. to: manage intermittency of renewable power sources, smooth dynamics of electrical power demands and decarbonise power sources, especially for electric and hybrid vehicles. Electron storage in chemical bonds offers high specific energies, electrochemical reactions being used to inject electrons into, and extract them from batteries, fuel cells or electrolysers.

3D inkjet printing is an efficient and scalable technology that can be used to fabricate solid oxide fuel cells (SOFCs) and electrolysers (SOEs), particularly during the R&D phase as prototypes can be produced rapidly. The steps involved in this process are:

  • formulation of printable inks;
  • fabrication of electrochemical reactor(s);
  • characterisation of their electrochemical performance.

This requires inputs from the disciplines of colloid science, rheology, and electrochemical engineering. When ink properties are optimised, 3D microstructures with pre-defined architectures can be fabricated reproducibly.

The project aims to develop 3D inkjet printing for fabrication of solid oxide electrolysers and fuel cells, thereby enabling reproducible electrolyte | electrolyte geometries to be fabricated with high densities of triple phase (electrode | electrolyte | pore) boundary lengths, so increasing reactor energy efficiencies, decreasing capital costs and achieving adequate robustness and hence lifetimes.

Aims and Objectives

Project aims

The project aims to develop 3D inkjet printing for fabrication of solid oxide electrolysers and fuel cells, thereby enabling reproducible electrolyte | electrolyte geometries to be fabricated with high densities of triple phase (electrode | electrolyte | pore) boundary lengths, so increasing reactor energy efficiencies, decreasing capital costs and achieving adequate robustness and hence lifetimes.

The project involves materials science and engineering, mathematical modelling, electrode | electrolyte and reactor design and fabrication, electrochemistry and electrochemical engineering, reactor performance characterisation, and process optimisation, with the aim of establishing relationships between materials, microstructures, properties and electrochemical reactor performance.

Electrochemical reactors using metal oxide materials for steam electrolysis at 700-900 °C to produce hydrogen and oxygen will be conceived, modelled, designed, characterised, controlled and optimised. 3D inkjet printing of metal oxide nano-particles is being used to fabricate electrodes, electrolyte | electrode structures as components of complete electrolysers and solid oxide fuel cells. The density of triple phase (electrode | electrolyte | pore) boundary lengths needs to be maximised, while minimising the spatial distribution of potential and current densities, especially normal to the electrolyte. The former will be achieved by simultaneous printing of continuous networks of NiO cathode precursors (i.e. Ni after reduction) and metal oxide (e.g. (ZrO2)0.92(Y2O3)0.08 yttrium-stabilised zirconia (YSZ)) electrolyte phases 10s of mms thick, together with a suitable organic phase to create well-defined pores after its combustion; metal oxide anodes (e.g. La0.8Sr0.2MnO3) will be deposited after sintering the cathode | electrolyte structures. Micro- and macro-spatial distributions of potential and current densities are being computed using finite element modelling to optimise the electrode and electrolyte thicknesses and geometries, thereby maximising reactor performance.

Ink