Introduction Of Lithium Battery Electrode Coating Technology

The main purpose of coating is to evenly coat the slurry with good stability, good viscosity and good fluidity on the positive and negative electrode surfaces. Its importance to lithium batteries is mainly reflected in three aspects: consistency, cycle life and safety.

During the coating process, if the coating thickness of the positive and negative electrode slurry at the front, middle and rear stages of the electrode piece is inconsistent, or the parameters before and after the electrode piece are inconsistent, it is easy to cause the battery capacity to be too low or too high, and lithium precipitation may be formed during the battery cycle, which will affect the battery life.

The coating process should strictly ensure that there are no particles, sundries, dust, etc. mixed into the pole piece, if mixed with sundries, it will cause a micro-short circuit inside the battery, and in serious cases, the battery will catch fire and explode. Therefore, in order to make the middle winding process as uniform and compact as possible, the coating error of the positive and negative electrodes is required to be as small as possible, and the advanced degree of the coating machine will directly affect the quality of the chemical properties of the battery, as well as the yield rate of the final product (battery manufacturers usually require more than 99%). The coating machine is the core equipment of the front-end process.

The coating machine has undergone the evolution of three types of structures, which are squeegee type, transfer type and slit extrusion type coating. The scraper type is mainly used in laboratory conditions; Transfer coating is mainly used in the production of 3C batteries; Slit extrusion coating is mainly used in power batteries, and this type has increased rapidly in recent years due to the explosion of demand for power battery production. Extrusion coating technology, the most advanced of the three, can be used to coat higher viscosity fluids to achieve high-precision coatings.

From the perspective of the structure of the lithium ion battery electrode coating machine , the design of the coating head has an extremely important impact on the coating accuracy, and the core components of such high-precision control still need to be imported. The technological advancement of coating machine equipment mainly examines four aspects: coating technology, tension technology, deviation correction technology, and drying technology. The coating technology needs to meet the production requirements of different thicknesses, and now the thickness of the cathode lithium battery aluminum foil has been as thin as 6-8 microns, the thickness of the negative lithium battery copper foil has been as thin as 4.5-6 microns, the separator coating is only a few microns, and the graphene coating is even thinner. 

Tension technology, because the web movement along the coating direction inevitably occurs uneven tension, resulting in a lack of consistency in coating quality, so it is necessary to ensure that each section of the sheet operation has good tension control. In order to ensure that both copper and aluminum films and very thin diaphragms can run smoothly and effectively on the sheet and achieve precision coating, it is necessary to choose different driving forms with response control systems to correct deviations. Drying technology, the speed bottleneck of coating production lies in drying and drying, the most direct means is to lengthen the bellows, but it will bring about an increase in cost and land occupation, and it is necessary to enhance the correction and tension control after strengthening, in order to further improve the drying efficiency, it is necessary to improve the control of the wind field, the control of the temperature field, the layout form, and try to reduce the length of the bellows under the condition of ensuring the coating speed.

Coating efficiency is an important criterion for leading companies to further compete with each other in terms of technical strength. At present, the leading coating machine equipment in the premise of ensuring the above technology, the main focus on improving the coating efficiency, the main means include increasing the running speed and coating width of the battery coating machine, the leading enterprises can reach 120m/min coating speed, coating width up to 1400mm.ACEY-AC300J lithium ion battery coating machine is a three-roll transfer coating equipment, which can be used for continuous and intermittent coating, and is convenient to apply to various substrate surface coating processes. Especially used in the lithium-ion battery industry, the equipment is designed to be convenient for researchers to use, and to meet the requirements of coating accuracy and consistency, which is no different from production. The drying effect is excellent. It is a lithium-ion battery, super capacitor, nickel battery and others. Ideal for secondary battery development and small trials.   

Acey New Energy is specialized in researching and manufacturing of high-end equipment for lithium-ion battery cell and pack.We can not only provide battery lab research machine, but also provide equipment for cylindrical, pouch cell, prismatic lithium ion battery pack assembly.If you are new in lithium ion battery industry, and want to build your own lithium ion battery production line or lithium ion battery pack assembly line, we can provide you professional technical support and guidance, please feel free to contact us!