Asahi Kasei Adds Wet-Process Coating at Charlotte Plant
Asahi Kasei's new Hipore coating line in Charlotte gives the separator maker North American wet-process capability at a Celgard site producing dry-process film since 1986.
Asahi Kasei has opened a Hipore wet-process lithium-ion battery separator coating line at its Celgard plant in Charlotte, North Carolina, giving the company North America-based coating and supply capability at a site that has made dry-process separators in the US since 1986.
Asahi Kasei has started up a Hipore wet-process lithium-ion battery separator coating line at its Celgard plant in Charlotte, North Carolina, giving the Japanese materials group its first North America-based coating and supply capability for wet-process separators. The site has produced dry-process separators in the United States since 1986, and the new line sits alongside that established business rather than replacing it.
The separator is the thin porous film that sits between the anode and cathode inside a lithium-ion cell. It has to keep the two electrodes from touching — a short circuit inside a cell is what leads to thermal runaway — while still letting lithium ions pass through during charge and discharge. It is one of the four core cell components, along with cathode, anode and electrolyte, and it is one of the few that has remained heavily concentrated in Asia even as North American cell assembly has multiplied.
Why the wet process matters for cell makers
Separator film is made two ways. The dry process stretches extruded polyolefin to open up pores mechanically. The wet process uses a solvent that is later extracted, producing a film with a more uniform pore structure that can be made thinner and stronger in both directions. Thinner separators free up internal volume for active material, which is why wet-process film has become the default for high-energy-density cells used in longer-range electric vehicles.
Coating is the second half of the equation. A ceramic or polymer coating applied to the base film raises its thermal stability and dimensional stability at high temperature, improves how well the electrolyte wets the surface, and helps the separator hold its shape under the compression of a wound or stacked cell. Coated wet-process separators are, in practice, a specification requirement for many current EV cell designs rather than an upgrade option.
By adding coating in Charlotte, Asahi Kasei can now offer both film families to North American customers from a North American address. Whether the base film for that coating line is produced domestically or shipped in for finishing, the company has moved the value-added step — the one most tightly specified by the cell maker and most sensitive to iteration — onto the same continent as the customer.
A 1986 plant asked to do a 2026 job
The Charlotte facility's longevity is the quiet detail in this announcement. A US separator plant that predates the commercial lithium-ion cell has been carried through several eras of battery demand, from consumer electronics to power tools to vehicles. Celgard's dry-process film built that history; the coating line is the site being retooled for the chemistry the current EV market buys.
Asahi Kasei acquired Celgard through its polypore purchase and has run the Hipore and Celgard brands as complementary lines — Hipore on the wet side, Celgard on the dry. Putting a Hipore coating line inside a Celgard plant collapses part of that split geographically, which should shorten qualification cycles for any customer that wants to evaluate both processes against a single cell design. Separator qualification is slow and expensive: samples, cycling data, safety testing, then line trials. Proximity does not eliminate that work, but it removes shipping time and customs from every iteration of it.
Localization pressure on the component tier
The broader trend this fits into is the migration of battery component supply from Asia toward the markets where cells are assembled. Cell plants came first, then cathode and anode projects, then the harder-to-move items: electrolyte, foil, binder, separator. Content and sourcing rules attached to US clean-vehicle incentives and to tariff exposure have made a domestic address commercially valuable in its own right, independent of freight cost.
The broader trend this fits into is the migration of battery component supply from Asia toward the markets where cells are assembled.
Separators have been slower to localize than cathode materials because the equipment is capital-intensive, the tolerances are tight, and the customer list is short. Each new line is therefore a meaningful data point about where the component tier expects demand to land. Asahi Kasei has not disclosed the investment figure or the nameplate capacity of the Charlotte coating line, so the scale of the commitment is not yet quantifiable from the public record. What is established is the capability and the location.
The details were reported by Charged EVs.
What to watch from here
Three things will tell investors and cell buyers how much this line matters. First, whether Asahi Kasei follows the coating step with wet-process base film production in North America — coating imported film localizes the finishing but not the substrate, and the tighter sourcing rules get, the more that distinction counts. Second, whether named customer agreements emerge; separator lines are usually built against commitments, and any disclosure of offtake would put a floor under utilization. Third, whether competitors respond with their own North American coating or film capacity, which is how a single plant turns into a regional supply base.
Asahi Kasei is not a US-listed operating company, and the Charlotte line is a component-tier investment rather than a headline number for equity markets. It landed on a broadly higher day for US benchmarks: as of the last trade at 20:00 GMT on Sept. 3, 2026, the S&P 500 tracker SPY was at $773.15, up 1.04%, the Nasdaq 100's QQQ at $717.67, up 1.19%, and the Dow tracker DIA at $536.93, also up 1.19%. For the EV supply chain, the more durable signal is structural: the parts of a battery that were hardest to move are starting to move, and North Carolina now has coating capability it did not have before.
Key facts
- What opened: Hipore wet-process lithium-ion separator coating line
- Location: Celgard manufacturing facility, Charlotte, North Carolina
- Existing site history: Dry-process separators produced in the US since 1986
- Market backdrop: SPY $773.15, +1.04%, as of 20:00 GMT Sept. 3, 2026
Frequently asked questions
What did Asahi Kasei open in Charlotte?
Asahi Kasei opened a Hipore wet-process lithium-ion battery separator coating line at its Celgard manufacturing facility in Charlotte, North Carolina. The line establishes North America-based coating and supply capability for the company's wet-process separators, adding that product family to a plant that has made dry-process separators in the United States since 1986.
What does a battery separator do?
A separator is the thin porous film placed between a lithium-ion cell's anode and cathode. It physically prevents the electrodes from touching, which would cause an internal short circuit, while still allowing lithium ions to move through it during charging and discharging. It is one of the four core cell components alongside cathode, anode and electrolyte.
How do wet-process and dry-process separators differ?
The dry process mechanically stretches extruded polyolefin film to create pores. The wet process uses a solvent that is later extracted, producing a more uniform pore structure that can be made thinner and stronger in both directions. Thinner film frees internal cell volume for active material, which is why wet-process separators are common in high-energy-density EV cells.
Why is coating the separator important?
A ceramic or polymer coating on the base film improves thermal and dimensional stability at high temperature, helps the electrolyte wet the surface, and helps the separator hold its shape under compression inside a wound or stacked cell. For many current EV cell designs, coated wet-process film is a specification requirement rather than an optional upgrade.
How much did the Charlotte coating line cost?
Asahi Kasei has not disclosed the investment amount or the nameplate capacity of the new coating line, so the financial scale of the commitment cannot be quantified from the public record. What has been confirmed is the capability itself — wet-process separator coating and supply based in North America — and the Charlotte location.
Why does localizing separator supply matter?
Battery component supply has historically been concentrated in Asia even as cell assembly expanded in North America. Separators have been among the slowest components to localize because the equipment is capital-intensive and tolerances are tight. Domestic capacity shortens qualification and shipping cycles for cell makers and can matter for sourcing and content rules attached to US clean-vehicle incentives.
Sources
Photo: cottonbro studio · Pexels Licence — source
