Pouch Cell Perspective: How New Solid-State Battery Standards Are Reshaping the Industry
At the end of December, China released its first national draft standard for solid-state batteries used in electric vehicles. While the document focuses on terminology, classification, and testing methods, its implications go far beyond policy—it directly affects how pouch cell technologies, suppliers, and OEMs position themselves in the market.
For companies working with lithium pouch cells, hybrid electrolyte systems, or next-generation solid-state designs, this draft standard provides a much-needed technical reference point.
Why Classification Matters for Pouch Cell Technology
One of the most important updates in the draft is the clear classification of batteries based on electrolyte type:
Liquid electrolyte batteries
Hybrid solid–liquid electrolyte batteries
Solid-state batteries
Notably, the commonly used but poorly defined term “semi-solid battery” is intentionally avoided. This is highly relevant for the pouch cell industry, where flexible packaging and evolving electrolyte systems often blur technical boundaries. With clearer definitions, classification becomes less about marketing and more about measurable technical behavior.
Mass Loss Rate: A Practical Criterion for Solid-State Pouch Cells
To distinguish solid-state batteries from hybrid designs, the draft introduces mass loss rate (weight loss under vacuum) as a core evaluation metric.
Industry validation tests referenced in the draft indicate:
True solid-state batteries (mainly sulfide-based systems) showed mass loss rates below 0.5%.
Hybrid solid–liquid batteries varied widely, from 1.68% to over 10%, depending on liquid electrolyte content and the ratio of solid material in the mixed electrolyte system.
As a result, the draft proposes 0.5% mass loss as the threshold for identifying a solid-state battery. For pouch cell developers, this suggests that electrolyte formulation and internal structure—not packaging format alone—will determine classification.
What the Test Method Tells Us About Pouch Cell Behavior
Beyond the threshold itself, the draft also clarifies how the test should be performed. This matters for pouch cells, where thin packaging, high surface area electrodes, and tight sealing requirements can influence the outcome.
Vacuum Conditions
The draft compares continuous vacuum holding versus periodic vacuum pumping. Test results suggest that for at least one hybrid solid–liquid cell sample, both approaches produced similar outcomes. For practical implementation, the draft recommends a continuous vacuum range of approximately –0.095 MPa to –0.1 MPa to improve convenience and repeatability.
Test Duration
Validation results also show that most mass loss occurs during the first 6 hours. The draft therefore sets 6 hours as the recommended test duration, while leaving room for continued verification as technologies evolve.
Why This Standard Matters to the Pouch Cell Supply Chain
Clear definitions and measurable criteria do more than standardize lab tests. They influence how suppliers, OEMs, and integrators communicate, compare technologies, and validate claims:
Clearer engineering communication — stakeholders can align on what “solid-state” means in a pouch cell context.
More focused R&D pathways — developers can benchmark electrolyte systems early and reduce ambiguity in performance claims.
More credible commercialization — marketing language is pressured to match testable, repeatable outcomes.
Better reference for certification and investment — mass loss rate provides a measurable indicator of electrolyte stability and maturity.
Implications for Solid-State Pouch Cell Supply
As solid-state battery development accelerates, the pouch cell format remains a practical platform for early-stage sampling, validation, and pilot-scale applications due to its flexible design and high energy density potential.
Current supply-side activity often includes:
Dry electrode or “dry cell” approaches paired with advanced cathode/anode systems
Hybrid electrolyte pouch cells transitioning toward lower liquid content
Single-layer or low-Ah solid-state pouch cells for validation, test builds, and sampling
For material suppliers, equipment vendors, and battery pack integrators, a standardized framework helps distinguish experimental concepts from engineering-ready solutions.
Looking Ahead
The draft standard is still open for public feedback, and further validation testing is planned. Thresholds and methods may evolve as solid-state technologies mature. However, one message is already clear:
For pouch cell developers, the future of solid-state batteries will be defined by measurable behavior—not terminology.
Companies that align early with transparent testing methods and realistic performance metrics will be better positioned as solid-state pouch cells move from lab samples to real-world deployment.
