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ZH Energy has long specialised in non‑fluorinated ion‑exchange membrane technologies. Leveraging its in‑house, fully‑controlled sulfonation modification process, the company has built three core product lines: PBI, SPEEK and SPPSU, covering diverse redox‑flow‑battery technical routes and application scenarios. Drawing on differentiated parameter‑customisation requirements from over 300 industry clients (e.g., degree of sulfonation, membrane thickness), ZH Energy has further standardised its SPEEK and SPPSU flow‑battery membranes into off‑the‑shelf product grades. Recently, both new‑generation membrane products have passed end‑to‑end mass‑production validation and are officially released for volume commercial supply.

Ion‑exchange membranes account for 8%‑10% of total system costs for redox flow batteries and represent a key target for cost reduction across the whole industrial chain. Perfluorosulfonic‑acid membranes have long dominated the market thanks to superior chemical stability; nevertheless, their high material cost remains a major bottleneck hindering flow‑battery system cost‑down. This market reality drives the industry to accelerate technical breakthroughs and mass‑scale commercialisation of high‑performance non‑fluorinated separators.

SPEEK Membrane: Low Swelling with Tunable Ion Selectivity

Sulfonated poly(ether ether ketone) (SPEEK) membranes are high‑performance non‑fluorinated ion‑exchange separators fabricated by precise sulfonation modification of poly(ether ether ketone) (PEEK) backbones. Ion‑selective performance can be accurately tuned by adjusting the degree of sulfonation, enabling a flexible balance between high ionic conductivity and effective electrolyte‑barrier properties. SPEEK membranes fit mainstream redox‑flow‑battery chemistries including zinc‑manganese, zinc‑bromine, zinc‑iron and all‑iron systems. They are also applicable to industrial electrodialysis separation processes.

Its molecular backbone built by ether linkages, ketone groups and aromatic rings delivers exceptional anti‑swelling performance under flow‑battery operating environments. The 60%‑sulfonation‑grade variant features an acid‑phase swelling ratio below 1%, while the 85%‑sulfonation grade achieves swelling ratios under 0.3%, fundamentally mitigating performance degradation triggered by dimensional swelling. Multiple grades of sulfonation degrees are commercially available, with standard thickness options at 25 μm and 50 μm to support diverse stack‑design selections.

SPPSU Membrane: Built for Longevity Under Harsh Operating Conditions

Sulfonated polyphenylsulfone (SPPSU) membranes are synthesised by sulfonation modification of polyphenylsulfone (PPSU) polymer backbones. Through tailored sulfonation chemistry, the material retains outstanding mechanical strength and chemical robustness while acquiring desirable ionic‑conducting and ion‑selective behaviour.

Its distinctive chemical structure grants outstanding durability under severe operating environments: strong alkaline conditions, highly oxidative media and high‑potential‑difference scenarios. Both acid‑ and alkali‑phase swelling ratios stay below 1%. SPPSU serves as one of the core enabling components for new‑generation redox flow batteries targeting long service lifetime and low system cost.

Mass‑Produced · Customisable · OEM‑Ready

Both non‑fluorinated membrane families are now in mass production, with stable performance verified by real‑world testing from more than 300 industry‑end users to guarantee reliable volume deliveries.

To accommodate varied customer requirements, ZH Energy provides full‑parameter customisation services:

• Adjustable degree of sulfonation, membrane thickness (15‑100 μm) and web width for compatibility with various flow‑battery systems;

• OEM membrane manufacturing and contract‑testing services to shorten clients’ R&D cycles and accelerate project execution plus cost optimisation.

Cost reduction for redox flow batteries cannot be accomplished by standalone products alone. It represents a systematic engineering effort spanning material systems, component design and mass‑manufacturing workflows. ZH Energy stands ready to collaborate with industry peers. Through systematic technology advancement, we jointly build the industrial foundation for flow‑battery cost‑efficiency improvement.