In the formation cycle of a lithium-ion cell, the standard ethylene carbonate (EC)/ethyl methyl carbonate (EMC) electrolyte undergoes reductive decomposition at the graphite anode surface. This decomposition is non-selective under baseline conditions, forming a solid electrolyte interphase (SEI) rich in inorganic lithium carbonate (Li2CO3) and lithium alkyl carbonates. Such a layer exhibits poor long-term passivation behavior when the cell cycles in a broad temperature window, particularly above 45 °C. Vinyl Ethylene Carbonate (VEC), added at 2–5 wt% to the baseline electrolyte, shifts the SEI chemistry. The vinyl group polymerizes during the initial charge at a potential of approximately 1.1–1.3 V vs. Li/Li+, creating a polymeric backbone that embeds the cyclic carbonate moiety. Cyclic voltammetry with a three-electrode Swagelok cell setup (working electrode: copper foil, reference: lithium metal) confirms an additional reduction wave distinct from the EC peak. The resulting SEI film is thinner (15–25 nm measured by transmission electron microscopy on extracted anodes) and richer in poly(vinylene carbonate)-type species.
Production-scale cell assembly lines using pouch or cylindrical formats (e.g., 18650 cells) require the electrolyte to be metered in an argon-filled glove box with moisture controlled below 10 ppm H2O and oxygen below 5 ppm. VEC-sourced electrolyte must pass a pre-fill quality gate: a Karl Fischer titration reading exceeding 15 ppm water results in immediate batch rejection, as residual moisture hydrolyzes the cyclic carbonate ring to diol intermediates, shifting the reduction potential and increasing SEI impedance. The high-purity grade (≥99%) limits acid impurities to below 50 ppm, preventing aluminum current collector corrosion that manifests as pitting after 300 cycles at 1C charge/discharge. In cycle life testing per IEC 62660-1:2019 (clause 7.4.2.2), cells with 3 wt% VEC additive demonstrate capacity retention of 92–94% after 500 cycles at 1C/25 °C, compared to 78–82% for the baseline electrolyte. The improvement stems from a stable SEI that suppresses continued electrolyte consumption, as evidenced by post-mortem gas chromatography of the extracted electrolyte showing 30–40% lower trans-esterification byproducts. However, a known operational boundary exists: VEC concentrations above 5 wt% cause an excessive increase in SEI film resistance, raising the DC internal resistance (DCIR) by 15–25% at the 50% state of charge, which degrades rate capability at discharge currents above 5C. Mixing equipment in production generally relies on planetary centrifugal mixers operating at 1500–2000 rpm for 5–10 minutes under vacuum to degas, with the VEC introduced after lithium salt (LiPF6) dissolution to avoid exothermic side reactions.
What Happens When VEC Replaces Part of a Monomer Feed in Emulsion Copolymerization?
Emulsion polymerization of all-acrylic pressure-sensitive adhesives frequently incorporates functional monomers to enable post-cure adhesion build-up. When VEC replaces 5–15% of the butyl acrylate (BA) charge in a semi-batch process, the reactivity ratios dictate compositional drift. VEC exhibits a Q-e value placing it closer to maleic anhydride than to typical acrylates; consequently, its incorporation rate lags behind BA during the early monomer feed stage. To compensate, a shot of VEC is often introduced during the final 30% of the feed, coinciding with a reduction in the surfactant (sodium dodecyl sulfate) concentration to 0.8–1.2% based on total monomer, which minimizes secondary nucleation. The resulting latex particles (D50 = 180–250 nm by dynamic light scattering, ISO 22412:2017) carry pendant cyclic carbonate groups on their surface. Residual monomer stripping via steam distillation at 60–65 °C under 200 mbar vacuum is critical; the cyclic carbonate ring begins to hydrolyze if the latex pH drifts below 5.5 during the stripping phase. This leads to diol formation that prematurely consumes the amine crosslinker added at the point of use. A processing bottleneck observed on pilot lines with a 200 L glass-lined reactor involves VEC’s tendency to homopolymerize in the vapor phase when the monomer emulsion feed line experiences dead zones. Installing a nitrogen purge across the monomer feed manifold and limiting the VEC storage temperature to 4–8 °C reduces gel seed formation.
The latex is subsequently compounded with an aliphatic diamine (e.g., isophorone diamine) at an amine-to-carbonate molar ratio of 0.9–1.1:1. The crosslinking reaction proceeds at ambient temperature over 72 hours, forming hydroxyurethane linkages. Gel fraction measured after 7 days by Soxhlet extraction in tetrahydrofuran (ASTM D2765-16, procedure A) reaches 85–92%, compared to 45–55% for non-reactive control latices. Peel adhesion on stainless steel (PSTC 101, 20-minute dwell) builds from 3.5 N/25mm before crosslinking to 8.2 N/25mm after full cure. One notable failure mode in manufacturing: if the diamine is added under high-shear conditions (above 3000 rpm using a Cowles blade), the instantaneous local viscosity increase triggers catastrophic flocculation. Production procedures specify slow addition under anchor agitation at 80–120 rpm. For export documentation, the VEC used in the monomer mix carries a TSCA inventory listing (CAS 4427-96-7) and is accompanied by a statement that the finished latex article complies with the EU Toy Safety Directive 2009/48/EC for migration of primary aromatic amines (none detected), as the crosslinker is an aliphatic species.
When VEC Serves as a Reactive Diluent in UV-Curable Hardcoats
UV-curable hardcoat formulations for polycarbonate glazing typically balance di- and tri-functional acrylate oligomers with reactive diluents to achieve 50–150 mPa·s at 25 °C. VEC acts as a monofunctional diluent that introduces a pendant cyclic carbonate. A typical formulation blends 20–30 wt% VEC with 40–55 wt% aliphatic urethane hexaacrylate and 5–10 wt% dipropylene glycol diacrylate. Photoinitiator (bis-acylphosphine oxide type) is added at 2.5 wt%. After bar coating at 12 μm wet thickness and UV curing at 1200 mJ/cm2 (measured at 395 nm UVA band), the cyclic carbonate groups remain intact in the network. These groups are later utilized for post-cure functionalization, where the hardcoat is exposed to an amine vapor at 60 °C for 10 minutes, converting the surface layer to hydroxyurethane moieties that increase surface energy from 32 mN/m to 44 mN/m (contact angle per DIN 55660-2). The resultant printability for UV inkjet inks eliminates the need for a separate primer.
On a flatbed coater equipped with a medium-pressure mercury lamp (H-bulb, 120 W/cm), the inclusion of VEC reduces the oxygen inhibition effect because the cyclic carbonate structure does not participate in radical quenching; this yields a tack-free surface at lower inert gas consumption. Pencil hardness (ASTM D3363) after amine treatment is maintained at 2H–3H, while the cross-cut adhesion (ISO 2409) to polycarbonate substrate remains 0–1 grade. A documented process limit is the viscosity drift during storage: VEC-containing formulations stored in opaque HDPE containers at 30 °C exhibit a 5–8% viscosity increase per month due to gradual thermal polymerization. To counteract this, the blended formulation is stabilized with 200–300 ppm of metquinol (MEHQ) and shipped under nitrogen blanket. Furthermore, the UV line speed must be adjusted when VEC exceeds 30 wt%; insufficient double bond conversion results in uncured extractables migrating to the surface under 85 °C/85%RH damp heat aging, causing haze increase above 2% (ASTM D1003). Patch testing on a 600 mm wide roll-to-roll line, using an in-line FT-NIR spectrometer to monitor acrylate conversion, showed that conversion dropped from 96% to 88% when VEC content was raised from 25% to 35% at a fixed line speed of 15 m/min.
Incorporating VEC into a polyester polyol backbone for two-component polyurethane (2K-PU) adhesives modifies the network architecture before isocyanate crosslinking. During the polycondensation of adipic acid with diethylene glycol at 200–220 °C in a stainless-steel reactor operated under nitrogen sweep, 3–8 mol% of the glycol component is replaced by VEC-derived diol. The cyclic carbonate ring of VEC first undergoes acid-catalyzed ring-opening with water present in the early stage, releasing a vicinal diol that incorporates into the polyester chain. This introduces pendant primary hydroxyls that alter the reactivity profile with the isocyanate hardener. Gel permeation chromatography (ISO 13885-1) of the resulting polyester polyol shows a slight broadening of molecular weight distribution (Đ from 1.8 to 2.3) due to branching, and the hydroxyl value rises from 55 mg KOH/g to 64 mg KOH/g. In a 50 kg pilot batch, the polyester cooled to 80 °C is discharged and combined with an aliphatic polyisocyanate (HDI trimer) at an NCO:OH ratio of 1.05:1.
The cured adhesive film exhibits lap shear strength on anodized aluminum (ISO 4587) of 12.5 MPa after 7 days at 23 °C/50%RH, compared to 9.8 MPa for the unmodified analogue. The improvement is attributed to the additional hydrogen-bonding capacity provided by the secondary hydroxyls formed during ring opening. However, a critical processing caveat is the reaction water content: the ring-opening step consumes stoichiometric water, and if the reactor is not adequately purged of residual moisture after alcoholysis, the batch will exceed the target acid number. A control strategy applied on production scale is to maintain the overhead condenser temperature at 98 °C and monitor the top of column pressure differential to confirm water removal completion before adding VEC. When sealed moisture persists, the acid number of the polyester remains above 2.0 mg KOH/g, causing a 20% decrease in pot life because the free acidity catalyzes the isocyanate reaction. The VEC-modified polyester polyol, when shipped under a nitrogen seal in 200 L drums, carries a specification sheet limiting free VEC monomer content to below 200 ppm (determined by headspace GC-MS), to avoid odor and sensitization issues in downstream lamination lines.
An Under-Utilized Application: Grafting VEC onto EPDM Rubber for Peroxide Cure Enhancement
Peroxide-cured ethylene-propylene-diene monomer (EPDM) rubber compounds in automotive weatherstrip profiles require co-agents to improve crosslink density and hot tear strength. While trimethylolpropane trimethacrylate (TMPTMA) is standard, VEC has been evaluated as a grafting co-agent in an internal mixing study on a 1.5 L laboratory Banbury mixer with tangential rotors. A base compound of EPDM (100 phr), carbon black N550 (80 phr), paraffinic oil (40 phr), and dicumyl peroxide (2.8 phr, 40% active) was modified with VEC at 2, 4, and 6 phr. The compound was mixed in an upside-down procedure: all dry ingredients added first, followed by oil and VEC in a single addition. The ram was lowered and mixing continued until a temperature of 115 °C was reached, then the batch was dropped immediately to avoid premature VEC homopolymerization, which occurs violently above 120 °C even in the presence of an internal antioxidant package. A two-roll mill finishing step at 40 °C was used to sheet the compound.
Moving-die rheometer data (ASTM D5289) at 180 °C showed that 4 phr VEC increased the delta torque (MH − ML) by 18% relative to the unmodified compound, and the scorch time ts2 shortened from 1.4 min to 0.9 min. The cyclic carbonate ring did not ring-open under these curing conditions; the crosslinking contribution was solely through the vinyl group. A notable failure on the production scale was observed when a 45 L internal mixer, operated with a similar time-temperature profile, encountered a batch that scorched prematurely because the VEC had partially polymerized in the drum during storage in a hot warehouse. The compound exhibited a surface roughness with visible gel particles, and the Mooney viscosity (ML 1+4, 100 °C) jumped from 55 MU to 78 MU, making it unusable for profile extrusion. This led to a shipping specification mandating VEC drums be stored below 15 °C and that the inhibitor (typically 50–100 ppm t-butyl catechol) be verified by UV spectrophotometry before batch charging. The final vulcanizate showed compression set (ISO 815-1, 22h/70 °C/25% compression) reduced from 28% to 22% with 4 phr VEC, meeting the OEM specification of ≤25% for door seal applications.
In printed circuit board (PCB) flexible coverlay films, a nitrile-butadiene rubber (NBR) modified epoxy adhesive is often blended with a latent amine crosslinker and applied to a polyimide film. VEC has been incorporated as a reactive adhesion promoter in a solvent-based adhesive formulation. The process begins by pre-reacting VEC (5 wt% of total solids) with a high-acrylonitrile NBR (ACN 41%) in methyl ethyl ketone at 80 °C under reflux for 2 hours. Free-radical grafting is initiated with 0.8 wt% benzoyl peroxide based on rubber solids. The resultant graft copolymer still contains intact cyclic carbonate groups, which later react with the amine hardener during the final lamination cycle. The stoichiometric amine-to-carbonate ratio is set at 0.8:1, leaving residual carbonate groups that contribute to dielectric stability. The mixed adhesive is coated onto 25 μm polyimide film using a comma coater and dried in a three-zone oven with highest zone temperature of 140 °C.
After lamination to a treated copper foil (IPC 4562 grade) at 160 °C and 2 MPa for 60 minutes, peel strength measured per IPC-TM-650 method 2.4.9 yields 1.8 N/mm as-bonded, and 1.5 N/mm after 10 days aging at 85 °C/85%RH. Without VEC, the peel values drop below 1.0 N/mm after humid aging. The production line collects volatile organic compound (VOC) emissions data: VEC contributes less than 0.05 kg VOC per kg adhesive solids because its boiling point (237 °C at 760 mmHg) limits volatilization during drying. A rejection event on a lamination press was traced to a batch where the cyclic carbonate groups had partially hydrolyzed due to an open solvent container. The hydrolyzed diol failed to react with the amine and instead plasticized the interface, causing delamination blisters during solder float testing (IPC-TM-650 2.4.13). Consequently, incoming quality control requires FTIR analysis of the VEC pre-reacted masterbatch, with acceptance criteria specifying a carbonyl peak absorbance ratio (cyclic carbonate 1795 cm−1 to ester reference) within 5% of the reference standard.
| VEC Addition Level (wt% in Electrolyte) | SEI Layer Resistance (Ω cm2 after Formation, EIS at 25 °C) | Capacity Retention at 500 Cycles (1C Charge/Discharge, 25 °C) | Cell Swelling after 500 Cycles (Thickness Increase, %) |
| 0 (Baseline EC/EMC) | 4.2–5.0 | 78–82 | 7.5–9.0 |
| 2 | 5.8–6.4 | 87–91 | 5.0–6.2 |
| 3 | 6.5–7.2 | 92–94 | 4.2–5.0 |
| 5 | 8.0–9.1 | 83–86 | 6.8–8.0 |
| Property | VEC-Free Polyester Polyol Adhesive | VEC-Modified Polyester Polyol (6 mol% VEC) | Test Standard |
| Hydroxyl Value (mg KOH/g) | 55 ± 3 | 64 ± 4 | ISO 4629-1 |
| Lap Shear Strength on Al (MPa) | 9.8 ± 1.2 | 12.5 ± 1.4 | ISO 4587 |
| Pot Life at 25 °C (min, to double viscosity) | 45–50 | 38–42 | Brookfield RV, spindle #6, 20 rpm |
| Free Monomer VEC (ppm) | <10 | <200 | Headspace GC-MS, internal method |
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Vinyl Ethylene Carbonate (VEC), IUPAC name 4-vinyl-1,3-dioxolan-2-one, CAS 4427-96-7, is supplied as a High Purity Grade with a minimum assay of ≥99.0% (GC area%, ASTM D4058). This cyclic carbonate monomer, a clear, colorless liquid at ambient temperature, combines a five-membered carbonate ring with a pendant vinyl group, enabling participation in both radical-induced addition polymerizations and ionic ring-opening pathways. The high-purity specification targets applications intolerant of protic residues: water content is certified below 100 mg/kg (ASTM E203), acidity as acetic acid below 50 mg/kg (ASTM D1613), and chloride below 5 mg/kg (ion chromatography, EPA 300.1). Physical constants include a density of 1.188–1.194 g/mL at 20°C (ASTM D4052), a refractive index n20D 1.450–1.455, a boiling point of 237–239°C at 101.3 kPa, and a flash point above 110°C (Pensky-Martens closed cup, ASTM D93). Unlike its saturated analogue ethylene carbonate—a solid below 36°C—VEC remains liquid down to −25°C, a feature exploited in low-temperature electrolyte blends without requiring co-solvent dilution.
What Limits the Substitution of Propylene Carbonate with VEC in UV-Curable Oligomer Backbones?
Radical copolymerization data for VEC with electron-deficient acrylic monomers reveals reactivity ratios (Fineman-Ross method, from J. Polym. Sci. Part A: Polym. Chem., 2005, 43, 3110) near r1 (VEC) ≈ 0.08 and r2 (methyl methacrylate) ≈ 2.5, classifying the pair as a strongly alternating tendency with a significant homo-propagation penalty for VEC. When a formulator substitutes propylene carbonate (PC, a non-reactive plasticizer) with VEC in a urethane acrylate oligomer matrix cured by UV-LED at 385 nm, the pendant vinyl ether moiety is partially incorporated into the network during post-cure, increasing crosslink density. Dynamic mechanical analysis (ISO 6721-11, dual-cantilever, 1 Hz, ramp 3°C/min) on films of 100 μm thickness showed that replacing 15 phr of PC with an equimolar amount of VEC elevated the storage modulus at 80°C from 42 MPa to 78 MPa, confirming anti-plasticization. However, the resulting network heterogeneity also concentrated stress: elongation at break (ASTM D638-14, Type V specimen, 50 mm/min) collapsed from 215% to 88%, and the onset of thermal decomposition in air (TGA, 10°C/min) dropped by 12°C, attributed to unreacted carbonate rings acting as labile sites. This property cliff-edge at addition levels above 12 phr in low-Tg urethane systems forces a narrow processing window where rigidity can be gained only with a severe ductility penalty.
On a twin-screw extruder (co-rotating, L/D 44:1, screw diameter 27 mm, zone temperatures 90–140°C) used for dispersing silica-filled polyethylene formulations, substitution of ethylene carbonate (EC) with VEC as a temporary polar processing aid was trialed at 2.0 wt%. The lower melting point of VEC eliminated the need for heated hoppers required by EC (m.p. 36.4°C), reducing pre-conditioning downtime. Yet torque readings at the kneading blocks increased by 8–11% compared to EC-equilibrated runs, indicative of a viscosity rise rather than the expected plasticization; the carbonate ring’s stronger association with silica silanol groups via hydrogen bonding—when not shielded by the saturated ethylene bridge of EC—retarded chain mobility. This effect inverted when the filler was hydrophobic fumed silica treated with dimethyldichlorosilane, where torque returned to baseline. Operators should expect this filler-dependent shift when reconfiguring from EC to VEC, particularly on narrow-diameter extruders with short residence times.
Electrolyte Additive Thresholds: SEI Passivation Versus Impedance Growth in LiNi0.8Co0.1Mn0.1O2 / Graphite Pouch Cells
In lithium-ion battery electrolytes, VEC is added at 1–3 wt% into standard 1 M LiPF6 in EC/ethyl methyl carbonate (EMC) (3:7 v/v) as a film-forming additive. Its reduction potential, determined by cyclic voltammetry on glassy carbon (scan rate 0.5 mV/s), occurs at approximately 1.4 V vs. Li/Li+, preceding carbonate solvent reduction and generating a poly(vinylethylene carbonate)-rich solid electrolyte interphase (SEI). In high-nickel NCM811/graphite pouch cells (capacity 2.5 Ah, formation at C/10 to 4.2 V, cycling at 1C at 45°C), incorporation of 2.0 wt% VEC depressed the post-formation CO2 gas volume measured by Archimedes’ principle from 4.8 mL (additive-free electrolyte) to 0.7 mL, extending the cycle life to 80% capacity retention by 620 cycles compared to 440 cycles for the baseline. Nevertheless, the effect is dose-sensitive: at 3.5 wt%, the post-cycle direct current internal resistance (DCIR, 10 s pulse at 50% SOC) rose by 45% vs. the 2.0 wt% level, and rate capability at 3C discharge sank to 83% of nominal capacity from 93%. The thickened SEI from excessive VEC oligomerization impedes Li+ transport—a trade-off quantified on symmetrical EIS cells showing interfacial resistance (RSEI) jumping from 4.2 Ω·cm² to 7.8 Ω·cm². These boundary conditions form a critical processing window of ±0.5 wt% around the optimum 2.0 wt%, beyond which cell manufacturability suffers from increased formation time and elevated reject rates for DCIR outliers per AEC-Q100-REV-H reliability stress-test grading.
Direct gravure coating of VEC-containing electrode slurries onto aluminum foil (NMP-based, PVDF binder, LFP active material) reveals an additional nuance: VEC’s relatively high surface tension (~42 mN/m vs. ~28 mN/m for PC) decreases wetting on plasma-treated current collectors when slot-die coating speed exceeds 6 m/min. Adding 0.2 wt% of a non-ionic fluorosurfactant (perfluoroalkyl-substituted polyethylene glycol, MW ~600) restored wetting without affecting SEI chemistry, as confirmed by XPS F1s/P2p ratio constancy. This process sensitivity is absent for ethylene carbonate or propylene carbonate at identical loading, making VEC demands on mixing apparatus—typically a planetary centrifugal mixer with degassing to −90 kPa—more stringent during slurry preparation.
When Halogen-Free Flame Retardancy in Polycarbonate Must Be Retained After Repeated Extrusion Cycles
VEC functions as a reactive charring synergist in phosphorus-based flame retardant packages, contrasting with the non-reactive plasticization of propylene carbonate. In a bisphenol-A polycarbonate (Lexan™ 143R) compound containing 12 wt% resorcinol bis(diphenyl phosphate) (RDP), replacing 3 wt% of the liquid RDP reservoir with VEC while keeping total phosphate loading constant yielded a UL 94 V-0 rating at 1.5 mm thickness after five injection molding recycle loops (barrel temperature 280°C, residence time 120 s). The 3 wt% VEC compound maintained a limiting oxygen index (LOI, ISO 4589-2) of 34.5%, whereas the all-RDP variant exhibited LOI drift from 34.8% on virgin pellets to 29.7% by the fifth pass due to RDP volatilization and hydrolysis-induced migration. Cone calorimetry (ISO 5660-1, 50 kW/m²) confirmed a peak heat release rate of 318 kW/m² for the VEC-stabilized compound after five cycles versus 422 kW/m² for the control. The improvement is traced to the vinyl group’s grafting onto polycarbonate chain ends during reprocessing, generating a non-volatile, phosphorus-anchored char precursor. A limitation emerges in transparent polycarbonates: even 1 wt% of VEC causes an increase in yellowness index (YI, ASTM E313) by 2.1 units after the first thermal history, owing to thermo-oxidative discoloration of the poly(vinylethylene carbonate) domains, disqualifying VEC from optical-grade articles.
Storage, Handling, and Pre-Treatment Requirements Under ISO 9001-Controlled Logistics
The product is packaged in 22 kg net-weight fluorinated HDPE drums or 200 kg stainless steel returnable containers, blanketed with dry nitrogen (<10 ppm O2, dew point <−50°C). Opening must be performed under a nitrogen sweep or in a dry room (dew point ≤−40°C) to prevent hydrolysis to 2-hydroxyethyl vinyl carbonate and subsequent acidity build-up. If water content exceeds 150 mg/kg upon receipt, the material can be dried by percolation through a column of 3A molecular sieves (pre-activated at 300°C for 4 hr) at 0.5 bed volumes/hr; vacuum distillation (10–20 mbar, 85–95°C head) restores assay above 99.5%. The liquid is incompatible with strong amines (e.g., triethylamine, imidazole) which catalyze ring-opening polymerization at ambient temperature, generating exotherms that can pressurize sealed containers. Storage stability under the recommended conditions: 12 months from date of certification when kept between +5°C and +30°C, away from direct light. Material freeze-thaw cycles (−20°C to +25°C) up to 3 repetitions show no assay loss when warmed under nitrogen with gentle agitation.
Comparative Carbonate Specifications Across Six Monomer Platforms
The following table condenses key physical and purity parameters for VEC alongside four related cyclic carbonates and one fluorinated derivative, enabling direct selection based on process temperature constraints, solvency, and reactivity to nucleophiles. While ethylene carbonate offers the highest dielectric constant, its solid handling requirements and limited miscibility restrict its use as a sole reactive diluent. Vinylene carbonate (VC) rivals VEC in SEI formation but decomposes exothermically above 60°C in the presence of LiPF6 acid spikes. VEC occupies a niche defined by a broad liquid range, a relatively high boiling point, and a single vinyl functionality that avoids the crosslinking oligomerization pathway typical of divinyl compounds.
Physical property comparison of high-purity cyclic carbonates (typical values, not specifications)
| Property | VEC (≥99%) | Ethylene Carbonate (EC) | Propylene Carbonate (PC) | Vinylene Carbonate (VC) | Fluoroethylene Carbonate (FEC) |
|---|
| CAS | 4427-96-7 | 96-49-1 | 108-32-7 | 872-36-6 | 114435-02-8 |
| Melting point (°C) | < −25 | 36.4 | −48.8 | 22 | 19–20 |
| Boiling point (°C) at 101.3 kPa | 237–239 | 248 | 242 | 162 | 210 |
| Density (g/mL at 20°C) | 1.19 | 1.32 (at 40°C) | 1.20 | 1.36 | 1.50 |
| Viscosity (mPa·s at 25°C) | 11.5 | solid | 2.5 | 1.9 | 4.1 |
| Flash point (°C) | >110 | 160 | 135 | 79 | 102 |
| Reactive unsaturation | 1 vinyl group | none | none | 1 vinylidene group | none (fluoro substituent) |
| Typical water content (mg/kg) in high-purity grade | <100 | <50 | <100 | <50 | <50 |
High Purity VEC specification (certificate of analysis limits)
| Parameter | Method | Limit |
|---|
| Assay (GC, area%) | ASTM D4058 | ≥99.0% |
| Water content | ASTM E203 (Karl Fischer coulometric) | ≤100 mg/kg |
| Acidity (as acetic acid) | ASTM D1613 | ≤50 mg/kg |
| Chloride (IC) | EPA 300.1 | ≤5 mg/kg |
| Color (APHA) | ASTM D1209 | ≤10 |
| Inhibitor (4-methoxyphenol) | HPLC-UV at 280 nm | 100±20 mg/kg |
Shelf life is 12 months from date of certification when stored unopened in original containers under nitrogen. Before use, drum contents must be homogenized by rolling for 30 min if crystallization of inhibitor has occurred near closure threads. Material withdrawn for electrolyte blending should be protected from ambient moisture with a dry air purge (dew point ≤ −60°C) and filtered through a 0.2 μm PTFE membrane to eliminate particulate precursors that seed lithium dendrite growth in finished cells.
