Properties of NMP and its role in lithium ion battery production

Nature of NMP

Chinese title of NMP: N-methylpyrrolidone

English title of NMP: 1-Methyl-2-pyrrolidinone

Chinese alias of NMP: NMP; 1-methyl-2-pyrrolidone; N-methylpyrrolidone (industrial grade); N-methylpyrrolidone (electronic grade)

NMPCASRN.：872-50-4

NMP molecular formula: C5H9NO

Physical and chemical properties of NMP: colorless transparent oily liquid with slight smell of amine.

NMP melting point: - 24.4 ℃

NMP boiling point: 203 ℃

NMP relative density: 1.0260

NMP refractive index: 1.486

NMP flash point: 95 ℃

NMP solubility: mutually soluble with water, alcohol, ether, ester, ketone, halohydrocarbon and aromatic hydrocarbon.

Use of NMP: It is widely used for the environmental protection disposal of NMP waste liquid, such as the refining of smooth oil, the synthesis of polymers, insulation materials, pesticides, pigments and cleaning agents. The used and dirty N-methylpyrrolidone can be recycled and applied through the solvent recovery machine and vacuum decompression system. Because of its relatively high boiling point, the direct recovery method cannot be used. After vacuum decompression, the recovery heating temperature can be reduced, the recovery quality can be guaranteed, and the improvement of the recovery safety factor has the above properties. It can be seen that the substance and water can be mutually soluble. The heat release you find is just the heat of dissolution released when it is dissolved in water, which is similar to the heat release when concentrated sulfuric acid is added to water. Attached dissolution heat: refers to the thermal effect produced when a certain amount of solute dissolves in the solvent at a certain temperature and pressure (usually the standard state of 298K temperature and 100kPa pressure). It is equal to the heat generated or absorbed when one mole of solute dissolves in roughly accumulated solvent.

The role of NMP in lithium ion battery production

Lithium ion battery is an internationally recognized ideal chemical energy source. It has the advantages of small size, large capacitance and high voltage. It is widely used in mobile phones, laptops and other electronic products. The expanding field of electric vehicles will bring more space for lithium ion battery development in the future. China and the world's major developed countries have introduced many policies to support new energy vehicles. The development plan of seven strategic emerging industries, including new energy vehicles, will be further promoted from the policy level. In 2009, the global output of lithium ion batteries was about 3.05 billion, and the total battery capacity was about 15000 WWh. The data shows that in 2013, the lithium battery capacity of electric vehicles reached 14000 WWh, which is equivalent to 93% of the global small lithium battery capacity in 2009. In 2018, the lithium battery capacity of electric vehicles reached 45000 Wh, which is equivalent to nearly three times of the small lithium battery capacity in 2009.

NMP is a nitrogen heterocyclic compound with a series of excellent physical and chemical properties. It is a non-toxic, high boiling point, strong polarity, low viscosity, low corrosivity, large solubility, low volatility, good stability, and easy to recover highly efficient selective solvent. It is widely used in petrochemical, pesticide, medicine, electronic materials and other fields.

NMP is a very important auxiliary material for the production of lithium ion battery electrodes. It is the most commonly used solvent in the front batching process of lithium ion batteries, commonly known as methyl, scientific name is N-methylpyrrolidone, and the molecular formula is C5H9N0. In the batching stage, as PVDF solvent, NMP participates in the slurry dispersion to form a slurry with uniform medium and long stability within a certain viscosity range.

In the coating stage: as the main liquid carrier of the slurry, it is evenly coated on the metal substrate with a stable thickness. It is required to have very good wettability and fluidity with the metal substrate. In the coating and baking stage: the wet film runs at a uniform speed in the oven, the solvent volatilizes regularly, NMP undertakes the pore forming function, and NMP volatilizes from the wet film at a stable speed to form a porous microelectrode structure with uniform pore diameter and uniform distribution.

The NMP waste gas recovery and treatment system and waste heat recovery device of the coating machine recover the NMP waste gas. After the air is purified, it meets the "zero" emission requirements. The waste heat recycling can achieve the heat energy saving efficiency of 65-80% according to the customer's requirements. The investment is small, the energy consumption is low, and the power is small. It is about 10% of the imported machine. It can meet and exceed the performance indicators of the Japanese NICHIAS hydrophobic zeolite ketone adsorption honeycomb runner without the runner, It is a cost-effective product.

NMP waste gas recovery and treatment system can be designed as 50-100% full closed cycle, solvent recovery

-The refrigeration internal circulation adsorption concentration technology is used to recover the organic solvent in the waste gas. The recovery rate of the organic solvent is more than 85-95%. Because of the large exhaust air volume and low concentration of the coater, the internal circulation is used to continuously concentrate the organic solvent in the waste gas to a certain concentration, and then the condensation recovery is carried out to reduce the recovery cost. At the same time, the product has the following advantages:

1. The solvent recovery efficiency is 85-95%, and the heat energy saving efficiency is 60-80%. For example, for the treatment of 10000 air volume, the ZN-FSQ-10000-1 combined solvent unit (including heat recovery unit) is used to recover 46kg/h of solvent (the indicators of the pole plate design are within the reasonable NMP concentration range of 10000 air volume, saving 187kw/h of electricity, and the value of recovered solvent plus saved electricity in one year is up to RMB 2 million (based on 10000 yuan/ton of recovered solvent, the electricity cost is 0.7 yuan/ton).

2. The content of organic solvent in the gas after solvent recovery treatment can be less than 39ppm, or meet the "zero" emission requirements. The NMP exhaust gas emission shall refer to the former Soviet Union working environment

* * Allowable Concentration of Harmful Organic Matter in Ambient Air and the standard requirements of emission rate calculated according to Technical Methods for Formulating Local Emission Standards of Air Pollutants (GB/T3840-91).

Fully meet the requirements of IS014000 and the national Integrated Emission Standard of Air Pollutants

GB16297-1996。

3. The air in the coater adopts closed cycle, and the influence of ambient temperature, humidity and air quality on the coating quality is reduced.