Lithium-ion battery electrode manufacture is the largest and fastest growing outlet, where NMP dissolves PVDF binder to make the cathode slurry. Electronics and semiconductor processing use it for photoresist stripping, wafer cleaning and polyimide work. At refinery scale it serves as an extraction solvent for aromatics, butadiene recovery and acetylene removal. Beyond those, it goes into high-performance coatings and wire enamels, industrial cleaning and paint stripping — an application now substantially restricted — and gas purification.

It is restricted rather than banned, and the distinction matters. Under REACH Annex XVII entry 71, applicable since May 2020, NMP may be placed on the market and used in the EU as a substance or in mixtures at 0.3% or above only where the derived no-effect levels are met — 14.4 mg/m³ for inhalation and 4.8 mg/kg body weight per day for dermal exposure — and where the supplier provides, and the user implements, appropriate risk management measures and operational conditions. In practice that means industrial use with proper containment continues; consumer and poorly controlled uses do not. Other jurisdictions including the United States have pursued their own restrictions, so the position should be confirmed for the destination market and application.

Because of what it has to dissolve. Lithium-ion cathodes are bound with polyvinylidene fluoride, a fluoropolymer chosen for its electrochemical stability in the cell, and very few solvents dissolve PVDF at all. NMP does, and it also disperses the active material and conductive carbon into a stable slurry with the rheology needed for precision coating onto foil, and it evaporates cleanly in the drying oven. Water-based binder systems exist and are established on the anode side, but transferring them to the cathode has proved difficult because the cathode chemistry is moisture sensitive and the aqueous systems reach different electrode structures. Substitution is being worked on seriously across the industry; it is not solved at scale.

Because it inverts the usual assumption. Most solvent exposure assessments are built around inhalation, and NMP has a very low vapour pressure, so air monitoring typically shows low concentrations and the operation looks well controlled. But NMP passes through intact skin readily, and dermal uptake can dominate the total dose in operations involving hand contact with wetted surfaces, wipes or components. This is why REACH sets a separate dermal DNEL alongside the inhalation one. The practical implication is that glove material and change frequency, and preventing incidental skin contact, deserve at least as much attention as ventilation.

The organic assay is only marginally higher — around 99.9% against 99.5% — but the specification is written on entirely different parameters. Electronic and battery grades are controlled for metals such as sodium, iron, calcium, copper and nickel in parts per billion, because trace metals in a photoresist strip or a cathode slurry cause device defects or electrochemical problems in the cell. Particle counts by size band are specified, the material is filtered and packaged accordingly, and water is held to 0.03% or below rather than 0.1%. Colour is tighter as well. For a battery or semiconductor application the metals and particle data are the specification, and the assay figure is almost incidental.

Every shipment includes a Certificate of Analysis covering purity, water, colour, acidity, amine value, gamma-butyrolactone, methylamine, non-volatile residue and iron, with metals and particle count data for electronic and battery grades; a Safety Data Sheet to GHS and REACH format including the exposure scenario and DNELs required under Annex XVII entry 71; SVHC communication under REACH Article 33; confirmation that the material is not regulated as dangerous goods; an origin certificate; and destination-market regulatory confirmation for the declared use.