Fabrication and characterisation of electrodeposited silver current collectors for metal-supported solid oxide electrolysis cells

Abstract

This work pioneers an efficient and scalable fabrication approach of silver (Ag) current collector (CC) layer on a porous stainless steel (SS-316L) tubular substrate for solid oxide electrolysis cell (SOEC). An Ag layer was fabricated on porous SS support using the electrodeposition technique. The highest current density 283 mA/cm2 was achieved with an optimised concentration of 0.1 M of AgNO3 solution containing 5.0 % HNO3 and an applied voltage of 2.0 V. It has been found that the strong acidic medium facilitates the migration of silver cations under controlled voltage towards the cathode. The structural properties were analysed by Raman spectroscopy and X-ray photoelectron spectroscopy to confirm the phase purity and structural properties of silver layer. The deposited Ag was a bright, uniform and well-adhered coating with an average coating thickness of 28 μm in the sintered tube. An improved electrochemical performance was attributed to the Ag-coated sample (σ = 1.24 × 10−4 S.cm−1) measured by impedance spectroscopy. The cyclic voltammetry studies of Ag coating reveal pseudo-capacitive behaviour due to its relatively low storage capacity. Ag-coated SS stable cathodic polarisation behaviour at higher potential (>1.99 V) with relatively higher corrosion potential (Ecorr = −0.05 V) signifies better corrosion resistant. AC impedance spectroscopy at 800 °C demonstrated that silver-coated SS current collector reduces area-specific resistance to 2.16 Ω·cm² in complete SOECs (SS/NiO-YSZ/GDC/LSCF-YSZ). This work underscores the transformative potential of Ag-coated SS tubular substrates can be used as an efficient cathode current collector, enhancing contact resistance, offering a promising route in developing next-generation SOEC.