Shanghai Semitech New Material Co., Ltd.
1628 Lijing Road, Lingang New Area, 200000, Shanghai, China.
Mobile:
+8615639100440
Email:
info@semitechnm.com
Pack Encapsulation, Sealing and ESS Anti-Corrosion
Lithium BatteryPack SealingESS Anti-Corrosion
Pack Encapsulation & ESS Anti-Corrosion
RTV silicone bases and weather-resistant pigments for batteries and energy storage
Once the cells are stacked, the pack still has to survive 15 years of vibration, humidity, salt fog, and thermal cycling. SEMITECH supplies silanol-terminated PDMS for module potting and zinc-phosphate-grade anti-corrosive pigment for outdoor ESS housing coatings.
Contents
Pack Specs
IP ratingIP67 / IP68
Op temp−40 to 85 °C
Salt fog>1000 h
Service life15 yr
Sealing the pack — why it gets harder every generation
Cell-to-pack and cell-to-chassis architectures eliminate the module case as a separate barrier. The full burden of waterproofing, vibration damping, and thermal isolation now falls on the pack-level encapsulation layer.
Three sealing functions converge in modern pack design. RTV silicone potting fixes cells to the pack base and damps vibration. Module sealing creates the IP67/IP68 barrier between coolant channels and electrical busbars. External anti-corrosion coatings protect the steel or aluminum housing — especially critical for stationary ESS containers exposed to coastal salt fog.
RTV silicone chemistry for pack potting
One-component RTV (room-temperature-vulcanizing) silicones are the workhorse for module potting. The base is silanol-terminated PDMS — exactly what SEMITECH MESIL OH polymer provides. Combined with a moisture-curing crosslinker (alkoxy or oxime), the polymer cures by exposure to atmospheric humidity, forming a high-elongation elastomer that absorbs vibration and accommodates cell breathing over thousands of charge cycles.
Why MESIL OH polymer for battery RTVs: SEMITECH’s silanol PDMS has tightly controlled molecular weight distribution (low-end tail removed), which keeps cured elastomer modulus consistent batch-to-batch. For battery applications where modulus drift translates directly to vibration response variability, this matters more than headline TS or elongation numbers.
ESS container anti-corrosion coatings
Stationary energy storage systems sit outside in conditions that EV packs never see — coastal salt fog, desert thermal cycling, industrial SO₂ exposure, and 20-year service expectations. The container coating system has to deliver more than aesthetics: it’s the first failure point if mechanical integrity goes.
SEMITECH’s anti-corrosive pigment line (zinc phosphate, modified) provides the active corrosion-inhibiting layer in epoxy primer coats applied to ESS container steel. Unlike chromate-based legacy chemistry, zinc phosphate meets RoHS / REACH and gives 1000+ hour salt fog performance when properly formulated.
SEMITECH product portfolio
MESIL OH Polymer
Silanol-terminated PDMS, viscosities 750–80,000 cSt. Base for one-component RTV potting compounds, module sealants, and gap-fill silicones. Tightly controlled MW distribution.
Anti-Corrosive Pigment
Zinc phosphate-grade and modified zinc phosphate. Designed for epoxy and polyurethane primer coats on ESS containers, charging station enclosures, and bus bars.
Fumed Silica (rheology)
SEMISIL 200 hydrophobic-treated grade for sag control in thixotropic RTV pastes. 1–3 wt% loading prevents drip on vertical surfaces during pack assembly.
Hydrogen / Vinyl Silicone
For two-component addition-cure pottants where cure-by-heat is preferred over moisture cure (e.g., closed-housing modules where atmospheric humidity is unavailable).
Selection guide
| Application | Function | SEMITECH Product | Reference Grade |
|---|---|---|---|
| Module potting (RTV) | One-component cure | MESIL OH Polymer | MESIL-OH 5000 |
| Module gap-fill | Two-component cure | Vinyl + H Silicone | MESIL VTM |
| Sag control | Thixotropy | Fumed Silica (hydrophobic) | SEMISIL 200H |
| ESS container primer | Anti-corrosion | Zinc Phosphate Pigment | SEMICOR ZP |
| ESS topcoat | UV resistance | Silicone-modified resin | By formulator |
FAQ
Why use silicone RTV for pack potting and not polyurethane?
Polyurethane gives higher tensile strength and adhesion at lower cost — but it stiffens dramatically below −20 °C and softens above 100 °C. Silicone RTV maintains elastomer behavior from −60 to 200 °C, which matches the actual EV operating envelope. For ESS in milder climates, polyurethane is sometimes acceptable. For automotive and northern climates, silicone wins.
What’s the difference between alkoxy and oxime cure RTV?
Alkoxy releases methanol or ethanol during cure — non-corrosive to copper bus bars, preferred for battery applications. Oxime releases methyl ethyl ketoxime, faster cure but slightly corrosive. Use alkoxy systems for any contact with electronics.
Is zinc phosphate RoHS / REACH compliant?
Yes. Standard zinc phosphate (Zn₃(PO₄)₂·4H₂O) is non-toxic and meets all current heavy metal restrictions. Modified versions (zinc aluminum molybdate orthophosphate) extend salt fog performance while staying compliant.
Can your RTV silicones contact lithium-ion electrolyte?
Cured silicone elastomers tolerate occasional contact with carbonate electrolytes at < 60 °C. For prolonged or high-temperature contact, request our chemical compatibility datasheet — we’ll recommend specific grades and cure systems.
Do you offer anti-corrosion pigment for marine ESS?
Yes. Modified zinc aluminum molybdate orthophosphate grades deliver >1500 h salt fog when formulated into a 2-coat epoxy/polyurethane system. Suitable for offshore wind ESS and coastal substations.
Part of the Lithium Battery Materials hub. Pack-level formulation support and ESS coating system advice available.