橡楚编辑部 9/11/2026 47 min read
This article sorts out the core characteristics of waterproof liquid silicone rubber seals for new energy equipment, explains their core advantages such as high and low temperature resistance, weathering and aging resistance, and long-term sealing stability, covers typical application scenarios including photovoltaic modules, energy storage cabinets, and new energy vehicle electronic control units, and shares practical key points for seal selection, installation and performance testing, providing technical references for practitioners in the new energy industry supply chain.
The global transition to renewable energy has accelerated the deployment of new energy equipment ranging from electric vehicle (EV) battery packs and onshore/offshore wind turbines to energy storage systems (ESS) and photovoltaic (PV) inverters. These assets operate in highly variable and often harsh environments: EVs face exposure to rain, road salt, and car wash high-pressure sprays; offshore wind turbines endure salt spray, tidal immersion, and extreme temperature fluctuations; and ESS units installed in outdoor locations must withstand monsoons, dust storms, and UV radiation. A single seal failure can lead to catastrophic consequences: water ingress into an EV battery pack may trigger short circuits and thermal runaway, moisture penetration into a wind turbine pitch system can cause component corrosion and unplanned downtime, and water damage to a PV inverter can reduce energy conversion efficiency by 15–20% and cut its service life in half.
Liquid Silicone Rubber (LSR) has emerged as the material of choice for waterproof seals in new energy equipment due to its unique combination of inherent water repellency, wide temperature tolerance, UV resistance, and long-term mechanical stability. Unlike traditional sealing materials such as nitrile rubber (NBR) or ethylene propylene diene monomer (EPDM), LSR maintains consistent performance across -60°C to 200°C, exhibits low compression set even after decades of cyclic loading, and is compatible with automated high-precision molding processes that meet the strict dimensional tolerances required for new energy applications. This article analyzes the core performance requirements of waterproof LSR seals for new energy equipment, evaluates material formulation optimization strategies, explores real-world application cases across key new energy segments, and outlines quality control frameworks to ensure long-term seal reliability.
The operating conditions of new energy equipment impose far more stringent performance demands on seals than those in traditional industrial applications. Seals must not only meet basic waterproofing standards but also demonstrate long-term resistance to environmental stressors, compatibility with adjacent system components, and compliance with industry-specific safety regulations.
The primary function of a waterproof seal is to prevent liquid and particulate ingress, and its performance is quantified using standardized test protocols and long-term durability metrics.
First, ingress protection (IP) rating compliance is the baseline requirement. For most new energy equipment, seals must meet IP67 or higher ratings: IP67 indicates full protection against dust ingress and the ability to withstand immersion in 1 meter of water for 30 minutes without leakage. For subsea components of offshore wind turbines and high-voltage EV battery packs, the more stringent IP6K9K rating is required, which mandates resistance to high-pressure (80–100 bar) high-temperature (80°C) water jets used in heavy-duty cleaning operations. LSR’s low surface energy (20–22 mN/m) and crosslinked molecular structure prevent water absorption, with typical water absorption rates of <0.1% after 24 hours of immersion, far lower than EPDM’s 0.5–1.0% absorption rate.
Second, seals must withstand long-term exposure to harsh environmental stressors without performance degradation. Table 1 summarizes the key environmental resistance performance metrics for LSR seals used in different new energy segments:
Third, seals must maintain waterproof performance under dynamic loading conditions. EVs experience continuous vibration during operation (10–2000 Hz frequency, 1–5 g acceleration), wind turbine blades are subject to cyclic bending loads (up to 10⁷ load cycles over a 25-year service life), and ESS units may experience thermal expansion and contraction cycles as charging and discharging rates vary. LSR’s high tear strength (25–40 kN/m) and excellent fatigue resistance ensure that seals do not develop microcracks or lose contact pressure under cyclic loading, with typical seal life ratings of 15–25 years for stationary new energy equipment and 8–10 years for EV applications.
Beyond environmental resistance, waterproof LSR seals must meet strict mechanical performance and safety standards to ensure compatibility with new energy system operation requirements.
First, dimensional precision and seal contact pressure are critical for consistent waterproofing. New energy equipment housings often have complex geometries with tight assembly tolerances: EV battery pack seal grooves typically have dimensional tolerances of ±0.05 mm, and wind turbine nacelle seal mating surfaces have flatness tolerances of <0.1 mm per meter. LSR’s low viscosity during molding allows for high-precision injection molding with part tolerance control of ±0.02 mm, eliminating gaps between the seal and mating surfaces. The required seal contact pressure varies by application: 0.3–0.5 MPa for static seals in PV inverters, 0.6–1.0 MPa for EV battery pack gaskets, and 1.0–1.5 MPa for high-pressure dynamic seals in wind turbine hydraulic systems. LSR’s low compression set ensures that contact pressure remains within the required range even after 1000 hours of compression at elevated temperatures, with pressure retention rates of >80% compared to <60% for EPDM seals under the same conditions.
Second, flame retardancy is a non-negotiable safety requirement for seals used in energy storage and EV applications. Due to the risk of thermal runaway in battery systems, LSR seals must meet UL 94 V-0 flame retardancy standards: specimens must stop burning within 10 seconds after exposure to a flame, with no flaming drips that can ignite surrounding materials. Unlike hydrocarbon-based rubbers that require large amounts of halogenated flame retardants that release toxic fumes when burned, LSR can be formulated with non-halogenated flame retardants (e.g., aluminum hydroxide, platinum-based additives) that achieve UL 94 V-0 performance with a smoke density rating (DS) of <300 during combustion, complying with EU RoHS and REACH regulations for hazardous substance restrictions.
Third, seals must demonstrate compatibility with adjacent materials and system operating media. EV battery seals come into contact with coolants (ethylene glycol-water mixtures, dielectric fluids), battery electrolytes, and thermal interface materials; wind turbine seals are exposed to hydraulic oils, lubricating greases, and biocides used in cooling systems; ESS seals may be in contact with phase change materials used for thermal management. LSR’s inert chemical structure ensures minimal swelling or degradation when exposed to these media: typical volume change of <2% after 1000 hours of immersion in EV battery coolant, compared to 5–8% for NBR seals under the same conditions. This compatibility eliminates the risk of seal shrinkage or swelling that could lead to water ingress or contamination of system components.
The performance of LSR seals is directly determined by their material formulation, which is tailored to meet the specific operating requirements of different new energy applications. Formulation optimization involves balancing base polymer properties, crosslinking systems, functional additives, and processing characteristics to achieve the desired combination of waterproofing, durability, and cost-effectiveness.
The base LSR polymer and crosslinking system are the foundation of seal performance, defining the material’s mechanical properties, temperature resistance, and long-term stability.
LSR is a two-part platinum-catalyzed addition-cure silicone system consisting of vinyl-terminated polydimethylsiloxane (PDMS) base polymer, hydride-functional PDMS crosslinker, and platinum catalyst. The molecular weight and vinyl content of the base polymer are adjusted to achieve the target hardness and mechanical performance: for soft, low-compression set seals used in EV battery packs, base polymers with molecular weights of 60,000–80,000 g/mol and vinyl content of 0.1–0.3 mol% are used, resulting in Shore A hardness of 40–50; for high-hardness, wear-resistant seals used in wind turbine dynamic applications, base polymers with molecular weights of 40,000–60,000 g/mol and vinyl content of 0.3–0.5 mol% are preferred, producing Shore A hardness of 60–70.
The crosslinking system is optimized to minimize compression set and improve waterproof performance. Traditional LSR crosslinking systems use a stoichiometric ratio of hydride groups to vinyl groups of 1.2:1 to 1.5:1, but for new energy seal applications, this ratio is adjusted to 1.5:1 to 2.0:1 to increase crosslink density. Higher crosslink density reduces the free volume in the polymer matrix, lowering water absorption by up to 30% and improving resistance to hydrolytic degradation. In addition, post-cure processing (200°C for 2–4 hours) is used to remove unreacted low-molecular-weight components, reducing volatile organic compound (VOC) emissions by >90% and eliminating the risk of seal outgassing that could contaminate sensitive electronic components in PV inverters or ESS control systems.
For applications requiring low-temperature flexibility, such as wind turbine seals used in cold climate regions (operating temperatures as low as -55°C), phenyl groups are introduced into the PDMS polymer backbone to reduce the polymer’s glass transition temperature (Tg) from -120°C for standard PDMS to -110°C for phenyl-modified LSR, while improving resistance to oil and hydrocarbon exposure. For high-temperature applications such as EV fuel cell seals, fluorine-modified LSR is used, which increases the material’s maximum operating temperature to 220°C and improves resistance to acidic fuel cell electrolytes.
Additives are incorporated into LSR formulations to enhance specific performance properties without compromising the material’s inherent waterproofing and thermal stability.
Flame retardant additives are the most common functional additive for new energy LSR seals. For UL 94 V-0 compliant formulations, two primary additive systems are used:
Hydrophobic modifiers are added to further improve LSR’s waterproof performance. 1–2 wt% of fluorinated silicone additives or nano-silica particles treated with hexamethyldisilazane (HMDS) are incorporated into the formulation, reducing the material’s surface energy from 22 mN/m to 18–20 mN/m. This increases the water contact angle from 110° for standard LSR to 120–130°, creating a superhydrophobic surface that repels water, salt spray, and road deicing chemicals. Long-term immersion tests show that hydrophobic-modified LSR has a water absorption rate of <0.05% after 1000 hours of immersion in 3.5 wt% NaCl solution, compared to 0.12% for unmodified LSR.
UV stabilizers are added for seals used in outdoor applications such as PV inverters and wind turbine exterior components. 0.5–1.0 wt% of hindered amine light stabilizers (HALS) and UV absorbers (e.g., benzotriazole derivatives) are incorporated into the formulation, reducing UV-induced chain scission and crosslinking. Accelerated xenon arc aging tests show that stabilized LSR retains >90% of its original tensile strength and elongation after 5000 hours of UV exposure, with no surface cracking or discoloration, compared to unmodified LSR which loses 30% of its tensile strength and develops microcracks after 2000 hours of exposure.
Waterproof LSR seals are deployed across the entire new energy value chain, from power generation to energy storage and end-use transportation. The following case studies illustrate how tailored LSR seal solutions address the unique waterproofing challenges of each segment.
EV battery packs are the most safety-critical new energy application, requiring seals that provide reliable waterproofing, thermal stability, and crash resistance over the vehicle’s 8–10 year service life.
A leading global EV manufacturer selected LSR gaskets for its 800V high-voltage battery pack, replacing the previous EPDM gasket design. The LSR gasket was formulated with 45 Shore A hardness, UL 94 V-0 flame retardancy, and low compression set (≤12% after 1000 hours at 85°C). The gasket was overmolded directly onto the aluminum battery pack upper housing using a two-shot injection molding process, achieving a bond strength of >3 MPa between the LSR and aluminum, eliminating the need for adhesive and reducing assembly time by 40%. The seal meets IP6K9K ingress protection, withstanding high-pressure car wash sprays and immersion in 1 meter of water for 30 minutes even after 1000 thermal cycles (-40°C to 125°C). In crash tests simulating a 50 km/h side impact, the LSR gasket maintained 100% waterproof integrity, preventing coolant leakage and water ingress that could trigger thermal runaway. Compared to the EPDM gasket, the LSR design reduced seal weight by 25% and extended seal life by 30%, supporting the manufacturer’s goal of 1 million kilometer vehicle durability.
LSR seals are also used in EV high-voltage connectors, charging ports, and power electronics enclosures. For DC fast charging ports, LSR seals provide IP67 protection even after 10,000 mating cycles, withstanding exposure to rain, snow, and road salt without degradation. The low temperature flexibility of LSR ensures that charging ports remain fully sealed even in -40°C winter conditions, eliminating the risk of ice formation that could prevent connector insertion.
Offshore wind turbines operate in one of the harshest environments on Earth, with seals exposed to salt spray, tidal immersion, extreme temperatures, and high cyclic loads over a 25-year service life.
A 12MW offshore wind turbine manufacturer developed a custom LSR seal for its blade pitch system, which adjusts blade angle to optimize power output and protect the turbine during high winds. The seal is a dynamic radial seal that operates at pressures up to 1.2 MPa and temperatures ranging from -40°C to 150°C, with a required service life of 25 years (10⁷ load cycles). The LSR formulation was optimized with 60 Shore A hardness, 5000-hour salt spray resistance, and low compression set (≤10% after 1000 hours at 100°C). The seal design incorporates a dual-lip configuration with a spring energizer to maintain constant contact pressure of 1.2 MPa against the rotating shaft, even as the seal wears over time. Field testing in the North Sea showed that the LSR seal had a leakage rate of <0.1 mL/hour after 5 years of operation, compared to the previous polyurethane (PU) seal which had a leakage rate of 5 mL/hour after 2 years, requiring costly replacement. The LSR seal reduced turbine maintenance costs by 60% over the 25-year service life, with a projected return on investment of 300% compared to the PU seal design.
For outdoor ESS installations, LSR seals are used in battery module housings, HVAC systems, and DC-DC converter enclosures. A 1MWh containerized ESS manufacturer adopted LSR gaskets for its outdoor units, which are deployed in desert and tropical coastal regions. The LSR seals meet IP67 protection, withstanding 2000 hours of salt spray exposure and 3000 hours of UV radiation without degradation. The seals maintain consistent waterproof performance even during thermal cycling from -30°C to 60°C, which occurs as the ESS charges and discharges, preventing moisture ingress that could cause battery cell corrosion and reduce ESS capacity by 20% or more.
Given the critical safety and operational implications of seal failure in new energy equipment, rigorous quality control and reliability validation processes are required throughout the product lifecycle, from material incoming inspection to long-term performance testing.
LSR seal manufacturing requires strict process control to ensure consistent dimensional accuracy, material properties, and bond strength for overmolded components.
First, incoming material inspection is performed for every batch of LSR raw material. Key test parameters include: