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Lithium battery production process and links

Lithium battery production process and links

August 25, 2023

Latest company news about Lithium battery production process and links

Lithium batteries are mainly composed of four parts: positive electrode, negative electrode, non-aqueous electrolyte and separator. At present, the lithium batteries used more in the market are mainly lithium iron phosphate batteries and ternary lithium batteries. The positive electrode raw materials of the two are quite different, and the production process is relatively close, but the process parameters need to change greatly. If lithium iron phosphate is fully replaced with ternary materials, the rectification effect of the old production line will not be good. For the relevant battery manufacturers, a large area of equipment on the production line must be replaced.


Lithium battery manufacturing process: the front, middle and back three processes, accounting for nearly 35%/30%/35%
The production process of lithium batteries is relatively complicated, and the important production process mainly covers the stirring and coating stage (front stage) of electrode production, the winding liquid injection stage (middle stage) of cell synthesis, and the packaging and testing stage (post stage) of chemical packaging. The proportion of value (purchase amount) is about (35~40%): (30~35)%: (30~35)%. The differences mainly come from different equipment suppliers, differences in import/domestic ratios, etc. The process flow is basically the same, and the value ratio is biased but generally in line with the ratio.


The lithium battery equipment corresponding to the front-end process of lithium battery production mainly includes vacuum mixers, coating machines, roller presses, etc.; the middle-end process mainly includes die-cutting machines, winding machines, stacking machines, liquid injection machines, etc.; the back-end process includes chemical forming machines. , capacity testing equipment, process warehousing and logistics automation, etc. In addition, the production of battery packs requires Pack automation equipment.


Lithium battery front-end production process: pole piece manufacturing is related to the core performance of the battery
The result of the lithium battery front-end process is that the positive and negative electrodes of the lithium battery are prepared. The first process is stirring, that is, mixing the positive and negative solid battery materials evenly, adding a solvent, and stirring them into a slurry by a vacuum mixer. The stirring of ingredients is the basis of the follow-up process of lithium batteries, and high-quality stirring is the follow-up


The basis for high-quality finishes in coating and rolling processes.
The coating and rolling process is followed by slitting, that is, the coating is subjected to a slitting process. If burrs appear during the slitting process, there will be safety hazards in the subsequent assembly, electrolyte injection and other procedures, and even the battery use process. Therefore, the front-end equipment in the production process of lithium batteries, such as mixers, coating machines, roller presses, and slitting machines, are the core machines of battery manufacturing, which are related to the quality of the entire production line. Therefore, the value (amount) of front-end equipment accounts for the entire lithium battery The proportion of automated production lines is the highest, about 35%.


Lithium battery mid-stage process: efficiency first, winding before stacking
In the lithium battery manufacturing process, the middle process is mainly to complete the forming of the battery. The important process includes sheet production, pole piece winding, die cutting, cell winding forming and lamination forming, etc., which is currently a relatively fierce competition among domestic equipment manufacturers. One area accounts for about 30% of the value of lithium battery production lines.


At present, there are mainly two types of cell manufacturing processes for power lithium batteries: winding and stacking. The corresponding battery structures are mainly cylindrical, square, and soft-packed. Cylindrical and square batteries are mainly produced by winding processes, and soft-packed lithium batteries The lamination process is mainly used. The cylinder is mainly represented by 18650 and 26650 (Tesla has independently developed the 21700 battery, which is being promoted in the whole industry). The difference between the square and the soft package is that the outer shell is made of duralumin shell and aluminum-plastic film, and the soft package is mainly made of lamination technology. Mainly, the aluminum shell is mainly based on the winding process.


The structure of soft packs is mainly aimed at the high-end digital market, and the profit margin per unit product is relatively high. Under the same output conditions, the relative profit is higher than that of aluminum shell batteries. Since aluminum-cased batteries are easy to form scale effect, product qualification rate and cost are easy to control, both currently have considerable profits in their respective market fields, and it is difficult for both of them to be completely replaced in the foreseeable future.


Since the winding process can realize the high-speed production of battery cells through the rotating speed, and the speed that the lamination technology can increase is limited, at present, the domestic power lithium battery mainly adopts the winding process, so the shipment volume of the winding machine is currently larger than that of the stacking machine. chip machine.


The previous process corresponding to winding and lamination production is the production and die-cutting of pole pieces. Sheet production includes welding pole pieces/tabs after slitting, dedusting pole pieces, pasting protective tape, tab wrapping and winding or cutting to length, in which the winding pole pieces are used for subsequent fully automatic winding, The fixed-length cutting pole piece is used for subsequent semi-automatic winding; the die-cut pole piece is to punch and shape the slit pole piece winding for subsequent lamination process.


In terms of lithium battery packaging and welding, Lianying, Han's, and Everbright's mainstream laser technology integration application manufacturers are all involved, which can meet the demand and do not need to import.


Lithium battery back-end process: capacity separation and formation is the core link
The post-production process of lithium batteries mainly includes four processes of capacity separation, formation, testing, and packaging and storage, accounting for about 35% of the value of the production line. Formation and capacity separation are the most important links in the back-end process. The formed battery is activated and tested. Due to the long charge and discharge test cycle of the battery, the value of the equipment is the highest. The important purpose of the formation process is to charge and activate the cells after liquid injection packaging, and the capacity separation process is to test the battery capacity and other electrical performance parameters after the battery is activated and to classify it. Formation and volume separation are performed by the formation machine and the volume separation machine, usually by an automated volume separation and formation system.


Lithium battery pack technology: it seems simple but must be combined with systematic design
The power lithium battery pack system is a battery pack that connects many individual cells in series and parallel, and integrates battery hardware systems such as power and thermal management. Pack is the key to the production, design and application of power lithium battery systems. It is the core link connecting upstream cell production and downstream vehicle application. Usually, the design requirements are put forward by cell factories or automobile factories, usually by battery factories, automobile factories or third parties. Pack factory completed.


The lithium battery Pack production line is relatively simple. The core processes include feeding, bracket sticking, electric welding, testing and other processes. The core equipment is a laser welding machine and various sticking testing equipment. At present, major lithium battery equipment manufacturers have few automation integration layouts in this field, while laser equipment manufacturers such as Han's Laser and Lianying Laser have a relatively high market share in the field of Pack equipment due to their absolute advantages in the laser field.


At present, the automation ratio of Pack production is relatively low, because the current sales of new energy vehicles are not large enough, and the cost of automatic production lines is relatively high.


Lithium iron phosphate and ternary: the topic of energy density cannot be avoided, and different materials require a complete set of equipment investment.


At present, the positive electrode materials of domestic mainstream power lithium batteries are divided into two types: lithium iron phosphate and ternary. Among them, lithium iron phosphate is currently the safest lithium battery cathode material, and its cycle life is usually more than 2,000 times. In addition, due to the decline in price and technical threshold due to the maturity of the industry, many manufacturers will consider it due to various factors. Using lithium iron phosphate battery. However, lithium iron phosphate batteries have obvious defects in energy density. At present, the energy density of BYD lithium iron phosphate single cell, the leading lithium iron phosphate battery, is 150Wh. By the end of 2017, BYD is expected to increase the energy density to 160Wh. In theory, lithium iron phosphate It is difficult for the energy density to exceed 200Gwh.


Ternary polymer lithium battery refers to a lithium battery in which nickel-cobalt-manganese oxide is used as the positive electrode material, and the actual ratio of nickel-cobalt-manganese can be adjusted according to specific requirements. As the ternary lithium battery has a higher energy density (the energy density of the ternary lithium battery of the first-class power lithium battery manufacturers such as CATL can generally reach 200Wh/kg-220Wh/kg, the industry expects that by 2020, the single cell of the ternary battery The energy density will reach the level of 300Wh/kg), the passenger car market has begun to turn to ternary lithium batteries, and lithium iron phosphate is more popular in passenger cars with higher safety requirements. With the development of all-electric passenger vehicles, ternary lithium batteries are occupying an increasingly important position.


The energy density and cost of the two materials are different, and different cars and different car companies have different choices. The production process of the two is roughly the same, and the difference is mainly reflected in the use and ratio of materials, the specific process parameters are quite different, the equipment cannot be produced on the same line, and the cost of simply transforming and switching output is high (ternary materials are relatively high) Vacuum dehumidification and other requirements are strict, and the previous lithium iron phosphate production line basically did not have dehumidification requirements), so many battery cell factories will simultaneously deploy and purchase equipment separately in production planning.


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