Why do lithium battery manufacturers prefer to NMP?

In the previous article, the editor mentioned that there are very few professional explanations about the application of NMP in the lithium battery industry, and they basically only exist in the research reports of researchers, or very professional research websites and forums. In order to give everyone a clearer understanding of NMP (N-methylpyrrolidone) as a solvent, it’s importance and indispensability for the preparation of lithium batteries, and in response to the messages of interested friends, the editor has carefully organized More relevant information will be presented to you one by one next.

1Q: What is the composition and proportion of NMP in the lithium batteries? (For more:<Revealed:Main applications of NMP solvents in lithium batteries.>)

Firstly let us to check what are the main parts in  Lithium battery? It is mainly composed of positive electrode materials, negative electrode materials, separators and electrolytes, etc. The positive materials account for more than 40% of the total cost of lithium batteries. It is understood that the performance of cathode materials, including NMP solvents, directly affects various performance  indicators of lithium batteries, which shows the core position of cathode materials in lithium battery manufacturing, including NMP ( N-methyl 2- pyrrolidone) solvent. But sorry, WIT FENGZE&ZESHENG focus on the production and supply of NMP solvents, as well as NMP waste liquid recovery systems and waste liquid solutions, which are still recognized by many big brands in the lithium battery industry and maintain long-term cooperation.

2Q: The cathode material of lithium battery and the various processes? (For more:<The production line of CATL is exposed! Why it was scrambled for Volkswagen, BMW or Mercedes-Benz?>)

The positive electrode materials of lithium battery includes positive electrode material (lithium cobalt oxide, lithium manganate , ternary material) + conductive agent (acetylene black) + binder (PVDF) + solvent (NMP) + current collector (aluminum foil);

The negative electrode material is: graphite + conductive agent (acetylene black) + thickener (CMC) + binder (SBR) + current collector (copper foil);

The production process of lithium battery:

The first step – electrode slurry preparation: mainly mix electrode active materials, binders, solvents, etc. together, and fully stir and disperse to form a slurry.

The second step – coating: The slurry prepared in the first step is uniformly coated on the current collector (aluminum foil or copper foil, etc.) with the specified thickness, and the solvent is dried.

The third step – pole piece punching: punch the pole piece produced in the previous step into the specified size and shape.

Step 4 – Lamination: Assemble the positive and negative plates and the diaphragm together, and form the pole core after the glue is applied.

Step 5 – Assemble the soft pack battery: put the pole core produced in the previous step into the aluminum-plastic film that has been punched in the hole, and complete the top seal, side seal, etc. soft pack battery.

Step 6 -Injection: Inject the specified amount of electrolyte into the inside of the pouch cell. Of course, the cells have to be baked and injected in a low-humidity environment. Too much moisture is not good.

The seventh step – battery sealing: extract the gas inside the battery cell in a vacuum environment and complete the sealing.

The specific process, the editor has also mentioned in the previous article, you can read it. Here, we will show you the discussions of relevant researchers on NMP solvents and PVDF binders:

3Q: How to choose a more suitable solvent for lithium battery manufacturing?

In the previous batching process of lithium batteries, the solvent that will be used in multiple stages is NMP. NMP solvent is like water and air, it is all around us, very common, but indispensable! Why is NMP selected for the solvent used in the slurry of lithium batteries? The solvent to be used in the lithium battery slurry should actually meet the following aspects: suitable for mass production and reasonable price; non-toxic, non-polluting and environmentally friendly; low melting point, high boiling point, and stable chemical properties; Modified resin.

After many experiments, scientists have studied various solvents such as H20, NMP, DMF, DMAC, DMSO, etc. The conclusion is that NMP and water are the best! But the solvent the scientists finally chose  NMP. Because the oily PVDF system is used in the cathode material, if such a combination is used: H20+CMC+SBR, it will cause various problems.

Choosing water as the solvent in the cathode material of lithium batteries will firstly cause the cathode materials to settle in the CMC+SBR glue system, which is not conducive to the stability of the slurry; secondly, it will cause the unsaturated bonds of SBR to occur at high potentials Oxidation, loss of cohesiveness, powder drop of the pole piece, and cycle deterioration are all important factors for the instability of the battery; thirdly, the later baking process is extremely difficult, because the specific surface area of the positive electrode materials is relatively large, if water is used as the Solvent, then after the positive electrode material particles show adsorption of water, it will increase the difficulty of the later baking process, thus greatly affecting the performance of the lithium battery.

Why are there so many battery fires and energy storage system explosions on the market? It is not only caused by improper use and charging, but also the performance of the battery is unstable. As a result of the instability of battery performance, all materials, various solvents, binders, etc., various processes and processes will have an impact on it. So don’t look at NMP solvent, it seems that it is not used much, but its quality, purity and production capacity will still have a certain impact on lithium batteries. For better NMP solvents, please pay attention to WIT FENGZE&ZESHENG! High-quality supplier in China’s new energy industry, focusing on the production and supply of NMP for nearly 10 years!

Ten years is an era, ten years can make a sapling grow into a big tree; it takes ten years to sharpen a sword, and the sword goes straight to the sky! WIT FENGZE&ZESHENG has experienced 10 years of industry tests, the production team is more professional, and the industrial reputation and reputation accumulated over the past 10 years are more trustworthy! It is our constant expectation to continue to provide NMP for the leading companies in the global lithium battery industry and provide better solutions that can change the world. We look forward to your joining!