RENEWABLE COUPLING
RENEWABLE COUPLINGOur NiCo Electrode for Renewable-Coupled Stacks
Electrolyzers coupled directly to solar and wind generation see variable current density throughout the day. Our bifunctional NiCo electrode in an AEM cell with a commercial Zirfon separator has been tested under both PV-derived and wind-derived current schedules.
Polarization (RT vs 60 °C)
TESTBED9-day solar cycling tested
PV-derived current schedule peaking ~570 mA/cm2 applied to the bifunctional NiCo electrode and commercial Zirfon separator for 9 continuous days. No major changes were observed.
100-hour wind cycling tested
Wind-derived schedule spanning 0 to 0.78 A/cm2 applied to the same cell for 100 hours. Linear-sweep curves before and after differ by 20 mV at 0.5 A/cm2.
91.4% efficiency at the operating point
In an AEM cell with bifunctional NiCo on both sides and commercial Zirfon as separator, 0.5 A/cm2 at 1.62 V at 60 deg C.
1000-hour steady-load stability
Continuous run at 0.5 A/cm2 and 40 deg C with bifunctional NiCo and commercial Zirfon: 21 uV/hr drift.
Renewable-coupled stacks see non-flat current
When an electrolyzer is wired directly to renewable generation (solar PV or wind), it does not see flat DC. It sees a daily cycle for solar and an irregular trace for wind. Catalysts and separators that work at steady state do not always tolerate the transients.
Our bifunctional NiCo electrode on Ni foam, electroless-deposited, has been tested in an AEM cell with a commercial Zirfon separator (500 um) under both kinds of dynamic profiles. The same coated electrode operates as HER cathode and OER anode at 80 mV and 260 mV overpotential at 100 mA/cm2 in 30 wt% KOH (no IR correction).
Continuous duration
Peak current density
Solar-irradiance-derived current schedule, 9 days
Solar-irradiance data sampled sunrise to sunset was converted into a current-density schedule peaking near 570 mA/cm2 and applied to the AEM cell with our bifunctional NiCo electrode on both sides and a commercial Zirfon separator. The cell was operated continuously for 9 days under this dynamic load at 40 deg C in 30 wt% KOH. The cell voltage tracked the input profile; no major changes were observed after 9 cycles.
Wind-variation-derived current schedule, 100 hours
Wind-speed variation data was sampled over 100 hours and converted to a current-density schedule with rapid gusts and sustained troughs, ranging from 0 to 0.78 A/cm2. The same bifunctional NiCo electrode and commercial Zirfon separator were used. Linear-sweep polarization curves before and after the 100-hour run differ by only 20 mV at 0.5 A/cm2.
The minor change after 100 hours of wind cycling indicates that the bifunctional NiCo electrode tolerates the dynamic-load envelope of wind-coupled operation.
1000-hour steady-load baseline
Alongside the dynamic-load runs, a continuous 1000-hour chronopotentiometry was performed with the same bifunctional NiCo electrode and commercial Zirfon separator at 0.5 A/cm2 and 40 deg C. The voltage drift over 1000 hours was 21 uV/hr. Before/after linear-sweep curves differ by 30 mV at the operating point.
PV-derived current profile
9 DAYSWind-derived current profile
100 HRWhat the renewable-coupled data does and does not show
The 9-day solar and 100-hour wind runs demonstrate that the bifunctional NiCo electrode and the commercial Zirfon separator hold the operating envelope under PV-derived and wind-derived current schedules. The runs do not project system-level outcomes for stack architectures we have not tested. Stack OEMs running their own balance-of-plant configurations should reproduce the dynamic-load envelope on their cell.
Frequently asked questions
Why use a bifunctional NiCo electrode for renewable energy integration?
Our bifunctional NiCo electrode operates as both HER cathode and OER anode at 80 mV and 260 mV overpotential at 100 mA/cm² in 30 wt% KOH (no IR correction). For renewable energy integration, using a single electrode SKU on both sides simplifies stack BOM and qualification.
What cell-level performance is published?
In a 5 cm² AEM cell with bifunctional NiCo electrode on both sides and a commercial Zirfon separator (500 µm) at zero-gap, the cell logs 0.5 A/cm² at 1.81 V at room temperature (82% efficiency) and 1.62 V at 60 °C (91.4%). At 1.0 A/cm²: 2.05 V at RT and 1.79 V at 60 °C.
What is the stability baseline?
Continuous 1000-hour chronopotentiometry at 0.5 A/cm² and 40 °C in 30 wt% KOH (bifunctional NiCo electrode on both sides, commercial Zirfon separator) showed voltage drift of 21 µV/hr. Before/after linear-sweep polarization curves differ by 30 mV at the operating point.
Is the electrode validated for renewable-coupled operation?
Yes. PV-irradiance-derived current schedules applied for 9 continuous days (peaks ~570 mA/cm²) and wind-variation-derived schedules for 100 hours (0 to 0.78 A/cm²) on the same cell. ΔV at 0.5 A/cm² before and after the 100-hour wind run: 20 mV.
What substrate sizes ship?
The bifunctional NiCo electrode is produced on Ni foam in the 100 to 1000 cm² size range. Bench-scale 5 cm² coupons matching the published test cell are also available so customers can reproduce numbers on their own rig before scaling up.
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