The growth of 3D printing has opened the scope for designing microstructures for solid
oxide fuel cell
s
(SOFCs) with improved power density and lifeti
me. This technique can
introduce structural modifications at a scale larger than particle size but smaller than cell
size,
such as by inserting
electrolyte pillars of ~5
-
100
µ
m. This study sets the minimum
requirements for the rational design of 3D printed
electrodes based on an electrochemical
model and analytical solutions for functional layers with negligible electronic resistance
and
no mixed conduction
. Results show that this structural modification enhances the power
density when the
ratio
k
eff
betwee
n effective conductivity and bulk conductivity of the ionic
phase
is smaller than 0.5. The maximum performance improvement is predicted as a function
of
k
eff
. A design study on a wide range of pillar shapes indicates that improvements are
achieved by any s
tructural modification which provides ionic conduction up to a
characteristic thickness ~10
-
40
µ
m without removing active volume at the electrolyte
interface. The best performance is reached for thin (< ~2
µ
m) and long (> ~80
µ
m) pillars
when the composite
electrode is optimised for ma
ximum three
-
phase boundary
density,
pointing towards the design of scaffolds with well
-
defined geometry and fractal structures.