ELECTRODE SPECIFICATION

SOLAR CYCLING

9-Day Solar Cycling Test

Solar-irradiance data sampled sunrise to sunset was converted into a current-density schedule and applied to our bifunctional NiCo electrode in an AEM cell with a commercial Zirfon separator for 9 continuous days. Peak current density ~570 mA/cm2.

SOLAR CYCLING

TESTBED
9-Day Solar-Coupled OperationAEM testbed · 40°C · 30 wt% KOH · current density from PV irradiance0.570j (A/cm²)1.951.40V (cell)1.80 V0123456789Time (days)9 days · no driftPV irradiance → current-density schedule applied to AEM stack with commercial Zirfon.

This spec

9 Days

SOLAR CYCLING

HER overpotential

80 mV

@ 100 mA/cm² (no IR)

OER overpotential

260 mV

@ 100 mA/cm² (no IR)

Cell @ 0.5 A/cm² / 60 °C

1.62 V

91.4% efficiency

1000-hour drift

21 µV/hr

@ 0.5 A/cm² / 40 °C

How the solar-coupled test was performed

Real-world solar-irradiance data was sampled from sunrise to sunset across 9 days and converted into a current-density schedule for the electrolyzer. The schedule peaks near 570 mA/cm2 during solar-noon windows and drops to zero overnight.

The schedule was applied to a 5 cm2 AEM cell with our bifunctional NiCo electrode on both sides and a commercial Zirfon separator (500 um) at 40 deg C in 30 wt% KOH. The cell was operated continuously across 9 days without resets.

  • Source: solar-irradiance data, sunrise to sunset
  • Conversion: irradiance to electrolyzer current density
  • Peak: ~570 mA/cm2
  • Duration: 9 continuous days
  • Cell: 5 cm2 AEM, zero-gap, 30 wt% KOH, 40 deg C
  • Components: bifunctional NiCo electrode (both sides), commercial Zirfon separator (500 um)

Result

Cell voltage tracked the input profile across all 9 days. No major changes were observed after the 9 cycles. The bifunctional NiCo electrode and commercial Zirfon separator together held their operating envelope across the full duration of the PV-derived schedule.

Why this test matters

A direct-coupled solar electrolyzer (without battery buffer) sees the full daily ramp-up, peak, and ramp-down cycle. Many catalyst and separator combinations show degradation under such transients that they do not show under steady DC. The 9-day result demonstrates that this particular electrode + separator combination tolerates the PV-coupled envelope across multiple consecutive cycles.

Where this specification matters

Industrial applications where solar dynamic load (9-day continuous) is a primary qualification metric.

Frequently asked questions

How is dynamic-load tolerance characterized?

Real PV irradiance (9 days) or wind variation (100 hours) was sampled and converted into a current-density schedule applied to the AEM cell with bifunctional NiCo electrode and commercial Zirfon separator. The 9-day solar run showed no major changes; the 100-hour wind run produced ΔV = 20 mV at 0.5 A/cm² before/after LSV.

How is solar dynamic load (9-day continuous) measured?

All published values were measured in a 5 cm² AEM cell with our bifunctional NiCo electrode on both sides, 30 wt% KOH electrolyte, zero-gap assembly, and a commercial Zirfon separator (500 µm) as the membrane reference. Overpotentials are reported without IR correction.

Can I reproduce this number on my own cell?

Yes. Bench-scale 5 cm² coupons matching the size used in our published AEM test cell are available. Reproducing the cell conditions (30 wt% KOH, zero-gap, commercial Zirfon separator, bifunctional NiCo electrode on both sides) lets a customer team confirm the published number directly.

What substrate sizes can I order?

We produce the bifunctional NiCo electrode on Ni foam in the 100 to 1000 cm² size range. Bench-scale coupons and pilot-scale electrodes both ship from this same product line. Specific sizes can be discussed for OEM stack integration.

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