Most people are rather confused as to what N-Methyl-2-pyrrolidone is, knowing only that it is a chemical and not exactly what it is used for. Even those in the lithium industry have not necessarily heard of it. Due to the rise of the new energy industry in recent years, lithium batteries have been widely used, indirectly leading to the commercial development of many raw materials. One of them is NMP solvent (full name N-Methyl-2-pyrrolidone), one of the co-materials of lithium battery cathode materials, which is also gradually known to the industry (e.g. the core team that manufactures the battery cells). Follow ZESHENG to take you into the world of NMP.

[What is N-Methyl-2-pyrrolidone?]

In fact, N-Methyl-2-pyrrolidone is the N-methyl derivative of 2-pyrrolidone. NMP belongs to the nitrogen heterocyclic compound, the molecular formula is C5H9O, and is a colorless transparent liquid high boiling point solvent (when left too long or stored in a relatively high humidity environment, it will slowly show light yellow, but does not affect the use).

NMP (N-Methyl-2-pyrrolidone) has the characteristics of strong polarity, inertness, low viscosity, strong solubility, good stability, non-corrosive, low volatility, etc.; it has been used in many fields such as lithium batteries, pharmaceuticals, petroleum extraction, food, daily chemicals, textiles, detergents, etc. It is mainly used as a solvent for polymerization reactions, and as a binder for PVDF and CNT diffusion solutions. The lithium battery industry happens to be ZESHENG's main focus, focusing on supplying quality NMP solvents to the new energy industry for 10+ years, thus having rich industry experience and hands-on experience in creating NMP recycling solutions. Follow ZESHENG to get instant NMP quotes.

[The production process of NMP(N-Methyl-2-pyrrolidone)]

There are two main ways to produce NMP, synthesis or recycling and purification. At present, the manufacturers with NMP synthesis technology can mass production, including BASF/GAF/Japan Mitsubishi/Pearson, and ZESHENG, etc.; while the recycling and purification technology and factories, respectively, Shandong Changxin Chemical, Jiangsu Tianna, Guangdong ZESHENG, etc.

[NMP in lithium battery cell production]

NMP(N-Methyl-2-pyrrolidone) is miscible with water, PVDF, positive grade materials, and other substances, and thus is widely used in the preparation of lithium batteries. When making electrode sheets, NMP is used as a solvent to fuse together various substances required for electrodes such as a binder, positive active material, and conductive agent, so that the binder can be fully contacted with other substances and evenly distributed.NMP, as one of the main auxiliary materials in the manufacturing process of lithium-ion battery cathode materials, has a direct impact on the quality of lithium-ion battery pulling slurry coating and environmental protection requirements.

Therefore, NMP(N-Methyl-2-pyrrolidone) is mainly used in lithium battery production for slurry mixing, coating, and other stages, as a diffusion solution to dissolve or swell the binder PVDF and CNT, and can be used to dilute the slurry. The concentration of NMP used in the manufacturing process of lithium batteries is generally required to be above 99.9% electronic grade.

[The main processes involved in the manufacture of lithium batteries by NMP are as follows]

Coating: A coating machine is used to apply the positive slurry (a mixture of lithium nickel cobalt manganate, conductive carbon black, solvent NMP, and binder PVDF) evenly on both sides of the aluminum foil.

The dryer uses an airtight negative-pressure extractor dryer (drying channel).

During the coating process, only a small amount of NMP is volatilized at the inlet and outlet of the coating machine. The exhaust gas in the dryer is led to the exhaust gas treatment facility through an induced draft fan and then discharged at a high altitude; a very small amount of NMP exhaust gas is disorganized and volatilized in the workshop due to insufficient drying etc.

Baking: After the coating is completed, the positive electrode sheet is baked and dried in the vacuum dryer at a temperature of 120±5°C; the NMP content on the electrode is removed. The dried gas enters the NMP recovery unit for recovery.

NMP accounts for about 3%-6% of the cost of manufacturing lithium-ion batteries. The market size and demand for NMP are also growing with the growth of lithium-ion batteries, especially energy storage batteries and power batteries. According to the incomplete statistics in the previous article, the production capacity of NMP is forecast to reach more than 2 million tonnes in 2025.

Although the industry has been studying how to replace NMP solvents, especially the European market considers NMP as a hazardous chemical. But in fact, NMP is a general chemical, it is not only used in the lithium battery industry, but also in semiconductor cleaning, pharmaceuticals, oil extraction, industrial cleaning agents, and other fields.

Moreover, with the continuous improvement of China's scientific and technological capabilities, large battery factories are now generally using closed automated production workshops, where staff does not directly touch or inhale NMP solvents; and as an integrated service provider of NMP supply and waste liquid recycling, the ZESHENG team is committed to creating a closed-loop NMP pipeline transportation and recycling system for customers, which fundamentally avoids NMP It can also save the battery factory a lot of money in project cost. The ZESHENG team is committed to creating a closed-loop NMP pipeline transport and recycling system for our customers.