MATERIAL COMPARISONVSCelgard PP/PE

IONZERA vs Celgard PP/PE

Celgard's polypropylene and polyethylene microporous separators dominate lithium-ion batteries, but how do polyolefin films compare to IONZERA's nanocomposite for alkaline electrolysis?

IONZERA0.09–0.1Ω·cm²Mesh-FreeDesign350–410μm thinZeroAsbestosTiO₂+GONanoAWEReady

Celgard Separators: Designed for Batteries, Not Electrolysis

Celgard LLC (a Polypore International subsidiary) manufactures microporous polypropylene (PP) and polyethylene (PE) separators primarily for lithium-ion battery applications. These separators are engineered for organic electrolytes, low-temperature operation, and thin-film battery cell designs.

Some researchers and early-stage AWE developers have explored using Celgard-type polyolefin separators in alkaline electrolysis cells. However, PP and PE are fundamentally hydrophobic polymers - they resist wetting by aqueous KOH electrolyte, which is the opposite of what an AWE separator requires.

Why Hydrophilicity Is Non-Negotiable for AWE

In alkaline water electrolysis, the separator must be thoroughly wetted by the KOH electrolyte to enable hydroxide ion transport. A hydrophobic separator creates a barrier to ion flow, increasing area resistance and reducing electrolyser efficiency. IONZERA addresses this requirement decisively:

IONZERA contact angle: ~24° - strongly hydrophilic, rapid electrolyte uptake and complete pore wetting
Celgard PP/PE contact angle: >90° - hydrophobic, requires surface treatment or additives to wet in KOH
TiO₂ nanoparticles in IONZERA provide inherent hydrophilicity that does not degrade over time
GO nanosheets further enhance wettability through oxygen-containing functional groups on their surface

Nanocomposite Structure

PSU-TiO₂-GO
OH⁻OH⁻OH⁻PSU MatrixTiO₂GO SheetsPores350-410 μm

Chemical Stability in Concentrated KOH

AWE separators operate in 25–30 wt% KOH at elevated temperatures - a highly aggressive alkaline environment. IONZERA's polysulfone (PSU) matrix is chemically resistant to concentrated KOH, with proven stability across the operating temperature range.

Celgard's polyolefin separators, while chemically inert to most organic solvents, can suffer from KOH-induced embrittlement and loss of mechanical integrity over extended exposure. They were simply not designed for this operating environment.

PSU matrix: proven chemical stability in 30 wt% KOH electrolyte at operating temperatures up to 45°C
PP/PE films: potential for alkaline-induced embrittlement and reduced mechanical strength over time
IONZERA's TiO₂+GO fillers enhance alkaline stability beyond the base polymer's inherent resistance

Use the Right Tool for the Job

Celgard separators are excellent products for their intended application - lithium-ion batteries with organic electrolytes. For alkaline water electrolysis, however, a purpose-built separator like IONZERA provides the hydrophilicity, alkaline stability, and optimized pore structure that polyolefin films cannot deliver. Using a battery separator in an electrolyser is a compromise that limits performance from day one.

Inherently Hydrophilic

24° contact angle vs >90° for PP/PE - complete KOH electrolyte wetting without surface treatment

KOH-Stable Chemistry

PSU-TiO₂-GO withstands 30 wt% KOH without embrittlement or degradation

Purpose-Built for AWE

Optimized pore size, porosity, and composition specifically for alkaline electrolysis conditions

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