Analysis of lithium battery manufacturing process

　　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-stage process mainly includes die-cutting machines, winding machines, laminating machines, liquid injection machines, etc.; the back-stage process includes formation machines. , volumetric testing equipment, process warehousing and logistics automation, etc. In addition, the production of battery packs also requires Pack automation equipment.

　　Pole piece manufacturing is related to battery core performance

　　The result of the lithium battery front-end process is to prepare the positive and negative electrode sheets of the lithium battery. The first step is stirring, that is, mixing the positive and negative solid-state battery materials evenly, adding the solvent, and stirring them into a slurry through a vacuum mixer. The mixing of ingredients is the basis for the subsequent lithium battery process, and high-quality mixing is the basis for the high-quality completion of the subsequent coating and rolling processes.

　　The coating and rolling process is followed by slitting, where the coating is slit. If burrs are generated during the cutting process, there will be safety risks during subsequent assembly, electrolyte injection, and even battery use. Therefore, the front-end equipment in the lithium battery production process, such as mixers, coating machines, roller presses, slitting machines, etc., are the core machines of battery manufacturing and are related to the quality of the entire production line. Therefore, the value (amount) of the front-end equipment accounts for the entire lithium battery production line. Automated production lines have the highest proportion, about 35%.

　　Efficiency comes first, winding goes before lamination

　　In the lithium battery manufacturing process, the middle process is mainly to complete the forming of the battery. The main process includes sheeting, pole piece winding, die cutting, cell winding and lamination forming, etc. It is currently a fierce competition among domestic equipment manufacturers. A field that accounts for about 30% of the value of lithium battery production lines.

　　At present, the cell manufacturing processes of power lithium batteries mainly include winding and lamination. The corresponding battery structures are mainly cylindrical, square, and soft-packed. Cylindrical and square batteries are mainly produced using the winding process, while soft-packed batteries are Mainly using lamination technology. The cylindrical ones are mainly represented by 18650 and 26650 (Tesla has independently developed the 21700 battery and is promoting it throughout the industry). The difference between square and soft packages is that the outer shells are made of hard aluminum shells and aluminum-plastic films respectively. The soft packages are mainly made of lamination technology. Mainly, the aluminum shell is mainly based on the winding process.

　　The soft package structure is mainly aimed at the mid-to-high-end digital market. The profit margin per unit product is relatively high. Under the same production capacity, the relative profit is higher than that of aluminum-shell batteries. Since aluminum-shell batteries are easy to form economies of scale, and product qualification rates and costs are easy to control, both currently have considerable profits in their respective market fields. In the foreseeable future, it will be difficult for both to be completely replaced.

　　Since the winding process can achieve high-speed production of battery cells through rotational speed, but the speed that lamination technology can increase is limited, domestic power lithium batteries currently mainly use the winding process. Therefore, the shipment volume of winding machines is currently larger than that of lamination. film machine.

　　The corresponding front-end processes for winding and lamination production are pole piece production and die-cutting. Production includes welding the slit pole pieces/lugs, dusting the pole pieces, applying protective tape, wrapping the tabs, and winding or cutting to length, in which the winding pole pieces are used for subsequent fully automatic winding. The cut-to-length pole pieces are used for subsequent semi-automatic winding; the punched pole pieces are rolled and punched into shape for subsequent lamination processes.

　　The back-end production process of lithium batteries mainly consists of four processes: volume separation, formation, testing and packaging and warehousing, accounting for about 35% of the value of the production line. Formation and volume separation are the most important links in the back-end process, and the formed batteries are activated and tested. Since the battery has a long charge and discharge test cycle, the value of the equipment is the highest. The main function of the formation process is to charge and activate the cells after liquid injection and encapsulation. The capacity dividing process is to test the battery capacity and other electrical performance parameters and classify them after the battery is activated. The formation and volume separation are performed by the formation machine and the volume separation machine respectively, usually by an automated volume separation and conversion system.

　　The power battery pack system is a battery pack in which many individual cells are connected in series or parallel. It integrates battery hardware systems such as power and thermal management. Pack is the key to the production, design and application of power battery systems. It is the core link connecting upstream cell production and downstream vehicle applications. Usually design requirements are proposed by the cell factory or automobile factory, usually by the battery factory, automobile factory or third-party Pack The factory is completed.

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

　　At present, the cathode materials of mainstream domestic power lithium batteries are divided into two categories: lithium iron phosphate and ternary. Among them, lithium iron phosphate is currently the safest lithium-ion battery cathode material. Its cycle life is usually more than 2,000 times. Coupled with the decline in price and technical threshold due to the maturity of the industry, many manufacturers have considered it due to various factors. Lithium iron phosphate batteries will be used. However, lithium iron phosphate batteries have obvious shortcomings in terms of energy density. The current energy density of BYD's lithium iron phosphate single cell, the leader in lithium iron phosphate batteries, is 150Wh. By the end of 2017, BYD is expected to increase the energy density to 160Wh. In theory, lithium iron phosphate The energy density is difficult to exceed 200Gwh.

　　Ternary polymer lithium batteries refer to lithium batteries that use lithium nickel cobalt manganese oxide as the positive electrode material. The actual proportion of nickel cobalt manganese can be adjusted according to specific needs. Since ternary lithium batteries have higher energy density (currently, the energy density of ternary lithium batteries from first-class power battery manufacturers such as Ningde Times can generally reach 200Wh/kg-220Wh/kg, the industry expects that by 2020, the single cell of ternary batteries Energy density will reach the level of 300Wh/kg), the passenger car market is beginning to turn to ternary lithium batteries, and lithium iron phosphate is more popular in buses with higher safety requirements. With the development of all-electric passenger vehicles, ternary lithium batteries are occupying an increasingly important position.

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