Lithium-ion battery is an internationally recognized ideal chemical energy source. It has the advantages of small size, large capacity, and high voltage. It is widely used in mobile phones, laptops and other electronic products. The expanding field of electric vehicles will bring more lithium-ion batteries in the future. Large space for development. China and the major developed countries in the world have introduced many policies to support new energy vehicles. The development planning of seven strategic emerging industries such as new energy vehicles will further advance China's electric vehicles from a policy perspective. In 2009, the global lithium-ion battery output was about 3.05 billion, and the total battery capacity was about 15000WMh. The data shows that the lithium battery capacity of electric vehicles reached 14000WMh in 2013, which is equivalent to 93% of the global small lithium battery capacity in 2009: electric vehicles in 2018 Lithium battery capacity reached 45000WMh, equivalent to nearly three times the capacity of small lithium batteries 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 corrosiveness, large solubility, low volatility, good stability, easy to recycle. Selective solvent. Widely used in petrochemical, pesticide, pharmaceutical, electronic materials and other fields.
NMP is a very important auxiliary material for the production of lithium-ion battery electrodes. The solvent commonly used in the front-end batching process of lithium-ion batteries is commonly called methyl, and its scientific name is N-methylpyrrolidone. Its molecular formula is C5H9NO.
In the batching stage: As a PVDF solvent, it participates in the dispersion of the slurry to form a uniform medium and maintains a stable slurry for a long time in 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 an even speed in the oven, the solvent volatilizes regularly, and NMP assumes the pore-forming function. NMP volatilizes from the wet film at a stable rate, forming a porous microelectrode structure with uniform pore size and uniform distribution.
The NMP exhaust gas recovery and treatment system and waste heat return device of the coating machine recover the NMP waste gas. After the air is purified, it reaches the "zero" emission requirement. The waste heat recycling can reach 65-80% of the energy saving efficiency according to customer requirements. Low investment, low energy consumption and low power, which is about 10% of imported machines. It can reach and exceed the performance indicators of Japan ’s NICHIAS hydrophobic zeolite ketone adsorption honeycomb runners without using wheels at all. It is a cost-effective product.
It works as follows:
I. The NMP exhaust gas recovery and treatment system can be designed as a 50-100% fully closed cycle, solvent recovery-using refrigeration-inner cycle adsorption concentration technology to recover organic solvents in the exhaust gas, the recovery rate of organic solvents is greater than 85-95%: The exhaust air volume of the cloth spreader is large and the concentration is low. The internal circulation of the organic solvent in the exhaust gas is continuously concentrated to a certain concentration, and then the condensation is recovered to reduce the recovery cost. At the same time, this product has the following advantages:
1. The solvent recovery efficiency is 85-95%, and the energy saving efficiency is 60-80%. For example: ZN-FSQ-10000-1 combined solvent unit (including heat recovery unit) is used to process 10,000 air volume, and the solvent is recovered at 46kg / h (the indexes of the pole piece design are in the NMP concentration range with reasonable air volume of 10,000, which saves The power is 187kw / h, and the value of energy saved by recycling the solvent in one year is RMB 2 million (based on the recovered solvent of 10,000 / ton, and the electricity cost is 0.7 yuan / calculated).
2. The content of organic solvents in the gas after solvent recovery and treatment can be below 39ppm, or reach the "zero" emission requirement. The NMP exhaust emission refers to the implementation of the "Large Allowable Concentration of Harmful Organic Matters in the Air of the Former Soviet Union Working Environment" and Technical Methods for Local Air Pollutant Emission Standards "(GB / T3840-91) calculated the emission rate standard requirements. It fully meets the requirements of ISO14000 and meets the National Comprehensive Air Pollutant Discharge Standard GB16297-1996.
3. The air in the coating machine adopts a closed cycle, and the influence of ambient temperature, humidity and air quality on the coating quality is reduced.
Second, waste heat recovery-using energy-saving technology to reduce the thermal energy consumption of the coating machine by 60-80%: Under normal circumstances, a large amount of gas is discharged during the coating process, and its temperature is generally around 110, while a large amount of fresh air is added to the coating Machine. Our company adopts advanced internal circulation sensible heat exchange heat transfer technology to exchange a small amount of heat between the exhaust gas and the fresh air supplemented to the coating machine, and most of it is not exchanged to be added to the coating machine immediately after purification treatment. Preheat the air replenished to the coater to about 85.5, so that the heating energy of the coater is reduced by about 60-80%, and the temperature of the air entering the surface cold is reduced to 55.
At present, most of the domestic users use the Chuyi measurement and control NMP solution concentration detector to perform real-time detection of the recovered NMP solution concentration. Generally, the recovered concentration of NMP liquid is between 75-85%. After reaching the set concentration value, it passes the PLC. Automatically control the liquid discharge pneumatic ball valve to discharge the waste liquid into the liquid storage tank, so as to facilitate the next process for rectification to form a high-purity NMP solution, which is directly used as a solvent for production. The relatively well-known domestic users are: Lishen Battery, Xingyuan Material, Guoxuan High-tech, etc.