| HS Code | 557236 |
| Product Name | Electrolyte for High-voltage NCM/SiOx@C Battery |
| Electrolyte Type | Liquid lithium-ion battery electrolyte |
| Lithium Salt | LiPF6 (1.0-1.2 M) |
| Solvent System | Carbonate-based (EC, EMC, DEC, DMC) with fluorinated co-solvents |
| Additives | FEC, VC, PS, LiDFOB, and high-voltage film-forming additives |
| Electrochemical Stability Window | 0.0-5.0 V vs Li/Li+ |
| Ionic Conductivity | 6-12 mS/cm at 25°C |
| Operating Temperature Range | -20°C to 60°C |
| Moisture Content | ≤ 10 ppm |
| Free Acid Hf Content | ≤ 50 ppm |
| Density | 1.15-1.25 g/cm³ at 25°C |
| Viscosity | 3.0-5.0 mPa·s at 25°C |
| Shelf Life | 12 months from date of manufacture under proper storage |
| Application | High-voltage NCM cathode / SiOx@C anode lithium-ion batteries |
As an accredited Electrolyte for High-voltage NCM/SiOx@C Battery factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 1 L sealed aluminum bottles under argon, with corrosion-resistant liner and tamper-proof cap for safe storage. |
| Container Loading (20′ FCL) | 20′ FCL container loading of high-voltage NCM/SiOx@C battery electrolyte, secured with proper packaging, labeling, and transport hazard compliance. |
| Shipping | This electrolyte must be shipped as hazardous material (UN Class 8, corrosive), in sealed, leak-proof containers with proper labeling. Avoid exposure to moisture, heat, or open flame. Transport via ground or air, complying with IATA/IMDG regulations, and include a Safety Data Sheet for handlers. |
| Storage | Store in a tightly sealed, corrosion-resistant container under inert gas (argon or nitrogen) in a cool, dry, well-ventilated area. Keep away from heat, open flames, oxidizers, and moisture. Avoid prolonged exposure to air. Use proper grounding during handling and wear suitable protective equipment. |
| Shelf Life | Shelf life: 6 months if stored sealed, cool, and dry; avoid moisture, heat, and light exposure. |
In cylindrical traction cell production for high-energy NCM/SiOx@C systems, electrolyte filling follows insertion of the jelly roll into a 21- or 46-series can and tab welding. The filling head operates in a dry room with dew point below -40 °C; residual chamber pressure is held below 1.0 kPa for 20-40 s before the metered dose of electrolyte is injected to a weight tolerance of ±1.0%. A representative baseline formulation is 1.0 M LiPF6 in EC:EMC 3:7 vol%, with 5.0 wt% FEC, 1.0 wt% VC, and 0.5 wt% LiPO2F2. Water content is limited to <20 ppm by ASTM E1064, and free-acid HF to <50 mg/kg by acid-base titration. The pot is then pressure-soaked at 0.7-0.9 MPa to force wetting through 80-100 µm coated cathode and SiOx@C anode layers. Formation starts with a 0.05C CC charge to 2.8 V, followed by a 12-24 h rest, then 0.1C CC-CV to 4.35 V with a 0.02C cut-off. Degassing follows at approximately 50% SOC. The final products are 21700, 4680, and pouch traction cells assembled into vehicle battery packs with liquid cooling; qualifying cells are tested under IEC 62660-2:2018 and UN 38.3. For EU-bound cells, the electrolyte supplier provides REACH (EC) No 1907/2006 Article 33 SVHC declarations and CLP (EC) No 1272/2008 classifications. Because the SiOx@C anode undergoes volume expansion approaching 120-180% during lithiation, the electrolyte must deliver both fluorinated SEI precursors and oxidation-tolerant cathode protection. Formation temperature is held between 25 °C and 45 °C; excursions above 50 °C accelerate LiPF6 hydrolysis and HF attack on the SiOx@C surface, which causes an impedance rise that is difficult to separate from SEI growth. Published post-test EIS and cell disassembly data for high-Ni NCM/SiOx@C configurations are limited, so the formation protocol is tuned batch by batch rather than by fixed stoichiometry.
Because the SiOx@C anode in eVTOL pouch cells is energy-dense but slow to wet, the filling station is configured around pulsed vacuum and pressure-assisted flow rather than gravity dosing. Electrode stacks of 30-80 Ah are inserted into aluminum-laminated film enclosures prior to injection, and stack thickness typically falls between 5 mm and 12 mm, creating long in-plane wetting paths across the separator. A formulation variant with 8.0 wt% FEC alone raises viscosity above 9 mPa·s at 25 °C; therefore a lower-viscosity blend of 1.0 M LiPF6 in EC:EMC 1:3 vol% plus 0.5 wt% DTD and 0.3 wt% LiDFOB is evaluated. The filling station uses pulsed vacuum from 10 kPa down to 0.5 kPa, with three pressure-recovery cycles; after sealing, cells are aged at 30 °C for 18-36 h before formation. Formation consists of a first charge at 0.02C to 2.5 V to establish the FEC-derived SEI, a second step at 0.05C to 3.6 V, then a slow CV pass at 4.40 V until current falls below 0.02C. The degassed cells are re-sealed and hot-aged at 45 °C for 72 h. Compliance for airworthiness includes RTCA DO-311A and UN 38.3; electrolyte documentation is aligned with Regulation (EU) 2023/1542 due diligence records. Terminal products are integrated eVTOL battery modules with forced-air or liquid cooling and redundant cell-level monitoring, where the electrolyte’s oxidative stability above 4.40 V is a precondition for high-state-of-charge cruise operation.
High-drain power tool cells based on 18650 or 21700 high-NCM/SiOx@C electrodes are filled with a low-viscosity electrolyte chosen for pulse discharge rather than for calendar life alone. The formulation in this segment shifts solvent composition to EC:EMC:DMC 2:2:6 vol% with 1.2 M LiPF6, 5.0 wt% FEC, and 0.5 wt% LiPO2F2; dimethyl carbonate is included to keep viscosity below 6 mPa·s at 25 °C. Filling is performed by multi-step vacuum dosing to a weight tolerance of ±2% per cell, followed by 24 h rotation at 25 °C to distribute low-viscosity solvent into the electrode pores. Formation includes a 0.1C CC-CV charge to 4.35 V and a 5C pulse discharge step used as a plating screening gate; cells with an end-of-pulse midpoint voltage below 3.0 V are diverted to low-rate applications. The plating screen is necessary because low-viscosity carbonates improve high rate capability but may reduce the robustness of the FEC-derived SiOx SEI during repeated 10C pulses at partial state-of-charge. Compliance is established under IEC 62133-2:2017 and UN 38.3. Terminal products are 18 V and 36 V power tool battery packs connected to brushless motors, where pack-level short-circuit and over-discharge protection sit outside the cell.
Electric ferry and mining truck propulsion cells subject the electrolyte to extended float at 4.30 V because the packs remain near full charge between operating cycles. Large-format prismatic cans are filled with a marine-duty formulation of 1.0 M LiPF6 in EC:DEC 1:1 vol% with 7.0 wt% FEC, 1.0 wt% 1,3-propane sultone, and 0.5 wt% TMSP. The propylene sultone additive is used for its sulfite-based cathode film under continuous 4.30 V float, while TMSP scavenges trace water and reduces HF generation during long-life operation. Injection is performed in a dry-room with dew point no higher than -30 °C; residual pressure is held at 0.8-1.5 kPa and the fill port is sealed after a 24-48 h low-pressure wetting soak. Formation uses a low initial current of 0.02C to 2.8 V, a 24 h rest, and then 0.1C to 4.25 V before a 4.30 V CV top-charge. Degassing ports are opened after the first formation cycle because gas generation from SiOx electrolyte reduction is highest in the first 48 h. Acceptance tests follow IEC 62619:2022, UN 38.3, and classification society documentation such as DNV type approval where required. The terminal products are battery strings integrated into marine propulsion DC buses and off-highway haul trucks, with cell-level state estimation set to conservative voltage limits to preserve the SiOx phase over multi-year calendar life.
| Downstream segment | Normative reference | Measurement or documentation anchor |
|---|---|---|
| Automotive traction | IEC 62660-2:2018 | cycle life, charge retention, 45 °C operational |
| eVTOL flight packs | RTCA DO-311A | cell and battery system airworthiness |
| Power tools | IEC 62133-2:2017 | portable cell safety, 10C pulse screening |
| Marine/off-highway | IEC 62619:2022 | industrial battery safety, float at 4.30 V |
| Consumer drone | IEC 62133-2:2017 | 3C charge / 6C discharge screen |
| Medical portable device | IEC 60601-1 | leakage and isolation, <15 ppm H2O |
High-rate consumer drone cell assembly lines target 3C fast charge and 6C continuous discharge, so the electrolyte reduces fluorinated additive loading relative to automotive formulations to limit viscosity. The formulation is 1.1 M LiPF6 in EC:EMC 3:7 vol%, 6.0 wt% FEC, 0.5 wt% DTD, and 0.5 wt% LiPO2F2. Vacuum filling is performed on stacked pouch cells with 2-4 mm total stack thickness to keep ionic diffusion paths short; end-of-fill weight variation is held to ±1.5%. Wetting is accelerated by 45 °C storage for 12-24 h at 0.6 MPa. Formation begins at 0.05C to 2.7 V, followed by 0.2C to 4.35 V with a 0.05C termination. A 3C charge and 6C discharge screen is applied after formation; cells showing more than 15 °C surface rise during the 6C discharge are diverted to standard-rate drone products. Compliance rests on IEC 62133-2:2017 and UN 38.3, with operator-facing documentation referencing RTCA DO-311A only for airframe-integrated packs. Terminal products are smart drone battery modules with integral cell balancing, authentication, and pack-level fusing.
Medical portable devices requiring high energy density in a sealed 18650 or small pouch cell use the NCM/SiOx@C electrolyte under tighter ionic purity controls. The formulation is based on 1.0 M LiPF6 in EC:EMC 3:7 vol% with 4.0 wt% FEC and 2.0 wt% VC, selected for lower initial gas generation and stable impedance over repeated partial cycling. Electrolyte filling takes place in an ISO 7 cleanroom; water content is measured by ASTM E1064 and limited to <15 ppm, with metal ion contamination below 1 mg/kg for Fe, Cu, and Zn. Fill weight is controlled to ±0.1 g on gravimetric dosing heads. Formation is a single 0.05C CC-CV charge to 4.30 V with a 24 h post-fill rest at 25 °C; no high-rate pulse screening is used because the device load profile is typically below 1C. Compliance documentation includes IEC 62133-2:2017, IEC 60601-1, and ISO 13485 risk management outputs, with UN 38.3 transport certification. Terminal products are battery packs for portable ventilators and infusion pumps, where the pack-level protector is set below the electrolyte’s 4.30 V cell limit to avoid over-lithiation of the SiOx phase.
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Electrolyte HV-4.45/SiOx-C-01 is formulated for lithium-ion cells pairing nickel-rich NCM cathodes—typically LiNi0.85Co0.10Mn0.05O2 or LiNi0.88Co0.09Mn0.03O2—with SiOx@C composite anodes. The release specification lists a lithium hexafluorophosphate concentration of 1.0 mol L−1, a lithium bis(fluorosulfonyl)imide concentration of 0.2 mol L−1, and a carbonate solvent mixture of ethylene carbonate/ethyl methyl carbonate/dimethyl carbonate at a volume ratio of 3:5:2. Fluoroethylene carbonate at 10 wt%, vinylene carbonate at 1.5 wt%, and 1,3-propane sultone at 0.5 wt% are the primary interfacial film-forming additives. The product is not a general-purpose carbonate electrolyte; the solvent/additive balance is adjusted for the simultaneous cathode oxidation boundary above 4.35 V and the volume-change problem of SiOx anodes.
At upper cutoff potentials above 4.40 V, two failure accelerants dominate. First, the delithiated NCM surface becomes oxidatively active, and carbonate solvents can undergo oxidative deprotonation and oligomerization unless a sulfur-containing or fluorinated species is present to form a cathode electrolyte interphase. The product’s 1,3-propane sultone and fluoroethylene carbonate function as sacrificial oxidation sinks. In linear sweep voltammetry on a platinum working electrode at 25 °C, the release limit permits no more than 0.05 mA cm−2 at 4.90 V vs Li/Li+ at a scan rate of 1 mV s−1.
Second, the SiOx@C anode undergoes repeated lithiation strain. Without a mechanically adaptive solid electrolyte interphase, cracking exposes fresh SiOx to further electrolyte reduction. The fluoroethylene carbonate content is therefore maintained at 10 wt%, higher than the 2–5 wt% commonly used in graphite-only cells. At this concentration, reduction onset occurs near 1.35 V vs Li/Li+, preceding bulk carbonate intercalation and depositing a polycarbonate/LiF network. Below 5 wt% fluoroethylene carbonate, the SiOx interface is insufficiently passivated; above 15 wt%, kinematic viscosity rises and bulk ionic conductivity falls below the specified minimum of 8.0 mS cm−1 at 25 °C.
The fluorinated salt and additive combination supplies two independent LiF sources: LiFSI decomposition releases fluoride at moderate potentials, while LiPF6 contributes fluorophosphate-derived LiF. This is an intentional distinction from LiPF6-only electrolytes, where the SiOx interphase tends to be carbonate-rich and less resistant to tensile strain. For pouch cells with an anode areal capacity of 2.0 mAh cm−2 and an NCM cathode loading of 3.5 mAh cm−2, formation includes a 4 h potential hold at 1.2–1.5 V to allow fluoroethylene carbonate reduction before bulk lithiation. Without this hold, the SiOx surface reacts with linear carbonate and increases ethylene gas accumulation in the sealed cell.
Each batch is released against an analytical panel. The water limit is 15 mg kg−1, and the free-acid limit is 20 mg kg−1; both are controlled because LiPF6 hydrolysis generates HF and phosphoryl fluoride, which accelerate transition-metal dissolution from the cathode and attack the aluminum current collector. Density is specified as 1.22–1.27 g cm−3 at 25 °C, and kinematic viscosity is specified as 3.4–4.6 mm2 s−1.
| Parameter | Test method | Release limit or typical value |
|---|---|---|
| Density at 25 °C | ISO 12185 | 1.22–1.27 g cm−3 |
| Kinematic viscosity at 25 °C | ASTM D445 | 3.4–4.6 mm2 s−1 |
| Water content | ASTM E203 coulometric Karl Fischer | ≤ 15 mg kg−1 |
| Free HF | acid-base titration in ice bath | ≤ 20 mg kg−1 |
| Ionic conductivity at 25 °C | electrochemical impedance spectroscopy, platinized Pt cell | 8.0–9.5 mS cm−1 |
| Oxidation current at 4.90 V | linear sweep voltammetry, 1 mV s−1 | ≤ 0.05 mA cm−2 |
| Metallic impurities, 12-element panel | ICP-OES after solvent digestion | sum of Fe, Ni, Cr, Cu, Zn ≤ 5 mg kg−1 |
| Filtration rating | filter integrity and gravimetric residue | filtered through 0.2 µm PTFE, β ≥ 5000 |
Filling and formation are the main process boundaries. Electrolyte transfer is performed in a dry room with a dew point at or below −45 °C. The product is pre-cooled to 10–15 °C before vacuum filling to reduce volatile losses of dimethyl carbonate. For pouch cells with SiOx@C anodes at 2.0 mAh cm−2, the recommended wetting procedure is −85 kPa gauge for 15 min followed by a 40 °C rest under 0.3 bar nitrogen overpressure for 20–30 min. Formation begins with a 0.05C constant-current step to 1.5 V, then the 4 h hold at 1.2–1.5 V, followed by 0.1C charge to 3.8 V with a 6 h rest. Degassing is performed only after the 3.8 V rest because premature opening disrupts the elastomeric polycarbonate interfacial film. The electrolyte is compatible with 1100-H14 aluminum current collector foil under the specified cathode potential boundary; it is not intended for lithium-metal anodes.
Sulfone- and nitrile-based electrolytes can exhibit oxidative onsets above 5.0 V vs Li/Li+, but their conductivities at 25 °C often fall in the 2–4 mS cm−1 range because of high solvent viscosity. The present product maintains a carbonate-ester backbone to keep conductivity in the 8.0–9.5 mS cm−1 corridor at 25 °C. This places the cell in a lower direct-current resistance production window: for a 7 Ah pouch cell with a 2.0 mAh cm−2 SiOx@C anode and a 3.5 mAh cm−2 NCM cathode, the 1 kHz area-specific impedance after formation is typically 7–12 Ω cm2. Published data for this specific configuration is limited; the range is based on manufacturer cell screening at 25 °C and 30% state of charge.
The tradeoff is a lower thermodynamic oxidative limit than sulfone-based systems. Continuous cycling above 4.50 V is not specified because carbonate oxidation products can accumulate as high-molecular-weight oligomers on the NCM surface. The electrolyte is therefore positioned below sulfone systems for 4.6–5.0 V applications but above conventional carbonate electrolytes for 4.35–4.45 V NCM/SiOx@C cells. Compared with standard 1 M LiPF6 in ethylene carbonate/ethyl methyl carbonate, the 0.2 M LiFSI co-salt and higher fluoroethylene carbonate loading reduce SiOx impedance rise during cycling. The LiFSI content is capped because increasing it above 0.5 M without sufficient LiPF6 passivation can accelerate aluminum pitting above 4.2 V.
Aluminum current collector passivation is a further boundary condition. The electrolyte is formulated so that the pitting potential of 1100-H14 aluminum exceeds 4.60 V vs Li/Li+ when measured at 0.1 mV s−1 in a three-electrode cell. At the upper cutoff of 4.45 V, the corrosion current remains below 2 µA cm−2. If the electrolyte is contaminated with water above 25 mg kg−1, free HF rises and the pitting onset drops below 4.40 V; wetting and filling must therefore be performed under closed-loop dry-air or nitrogen. The product should not be combined with protic additives, amine-based stabilizers, or unreacted carboxylic acid impurities because they neutralize the acidic fluorophosphate buffering system and destabilize the interfacial composition. Storage is specified at 0–10 °C in sealed 200 L stainless steel drums with 0.3 bar nitrogen overpressure. Excursions above 45 °C should be limited to 72 h because the HF generation rate accelerates; if a batch exceeds this thermal excursion, the free-acid limit should be rechecked before use. Contact with ambient air should remain below 10 min at relative humidity above 60%; otherwise, pre-drying of packaging or the dosing line is required.
