Interfacial and Kinetic Origins of Voltage Loss in Neutral Zinc‐Air Batteries

Why It Matters

Neutral zinc‑air systems promise safer, low‑cost grid storage, but voltage inefficiencies threaten commercial viability and must be resolved for large‑scale adoption.

Key Takeaways

• Neutral Zn‑air cells show stable cycling over hundreds hours
• Electrolyte suppresses oxygen evolution kinetics, raising overpotentials
• Metallic Zn deposits on air cathode, causing voltage loss
• Ni/Fe‑LDH remains OER‑biased, not limiting performance
• Ohmic resistance contributes minimally to observed voltage drop

Pulse Analysis

Neutral‑electrolyte zinc‑air batteries are attracting attention as a potentially safer alternative to alkaline designs for grid‑scale storage. By replacing highly caustic alkaline solutions with ZnCl₂‑based gel polymer electrolytes, manufacturers aim to reduce corrosion, simplify handling, and lower material costs. However, the shift in chemistry introduces new interfacial dynamics that can erode performance. Understanding how these neutral media interact with both the air cathode and the zinc anode is essential for translating laboratory prototypes into reliable, commercial‑grade energy assets.

In the reported work, researchers paired a ZnCl₂‑soaked KC‑PAA‑PAM gel with an electrochemically synthesized Ni/Fe layered double hydroxide catalyst deliberately biased toward the oxygen evolution reaction. This configuration allowed the team to isolate electrolyte‑driven limitations rather than catalyst deficiencies. Advanced diagnostics, including synchrotron soft X‑ray absorption and post‑mortem X‑ray photoelectron spectroscopy, identified two dominant loss pathways: a pronounced slowdown of oxygen kinetics within the neutral electrolyte and the formation of metallic zinc on the air‑cathode surface. Both phenomena raise the cell’s overpotential, while impedance measurements confirm that simple ohmic resistance plays a secondary role.

The findings carry clear implications for the energy storage market. Engineers must prioritize electrolyte formulations that preserve oxygen reaction rates and suppress zinc plating on the cathode, perhaps through additive strategies or protective interlayers. Simultaneously, the stability of Ni/Fe‑LDH under neutral conditions suggests that catalyst development can focus on bifunctionality without sacrificing durability. Addressing these interfacial challenges could unlock higher round‑trip efficiencies, making neutral zinc‑air batteries a competitive option for renewable integration and long‑duration storage projects.