Discussion on the current production process and flow of AAA rechargeable battery

　　Lithium-ion batteries are mainly composed of four parts: positive electrode, negative electrode, non-aqueous electrolyte and diaphragm. At present, the AAA rechargeable battery used more in the market are mainly lithium iron phosphate batteries and ternary AAA rechargeable battery. The raw materials of the positive electrodes of the two are quite different. The production process is relatively similar, 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 is not good. For battery manufacturers, it is necessary to replace a large area of equipment on the production line.

　　Lithium battery manufacturing process: front, middle and back three processes, accounting for nearly 35%/30%/35%

　　The production process of AAA rechargeable battery is relatively complicated. The main production process mainly covers the stirring and coating stage (front stage) of electrode production, the winding and liquid injection stage (middle stage) of battery cell synthesis, and the packaging and testing stage (back stage) of chemical packaging. The value (purchase amount) accounts for about (35~40%): (30~35)%: (30~35)%. The difference mainly comes from different equipment suppliers and differences in the proportion of imports/domestic products. The process is basically the same, and the value share is biased but generally in line with this proportion.

　　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, laminating machines, liquid injection machines, etc.; the back-end process includes formation machines, capacity detection equipment, process storage and logistics automation, etc. In addition, the production of battery packs also 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 front-end process of AAA rechargeable battery is to prepare the positive and negative pole pieces of AAA rechargeable battery. The first process is stirring, that is, mixing the positive and negative solid-state battery materials evenly and adding solvents, and stirring them into a slurry through a vacuum mixer. The stirring of ingredients is the basis of the subsequent process of AAA rechargeable battery, and high-quality stirring is the basis for the high-quality completion of the subsequent coating and rolling processes.

　　After the coating and rolling processes, slitting is performed, that is, the coating is subjected to slitting process. If burrs are generated during the slitting process, there will be safety hazards in the subsequent assembly, electrolyte injection and other procedures, and even during the use of the battery. 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, which are related to the quality of the entire production line. Therefore, the value (amount) of the front-end equipment accounts for the highest proportion of the entire lithium battery automation production line, about 35%.

　　Lithium battery mid-stage process: efficiency first, winding before lamination

　　In the lithium battery manufacturing process, the mid-stage process is mainly to complete the battery molding. The main process includes film making, pole piece winding, die cutting, battery cell winding and lamination, etc., which is a field where domestic equipment manufacturers are currently competing fiercely, accounting for about 30% of the value of the lithium battery production line.

　　At present, there are two main cell manufacturing processes for power AAA rechargeable battery: winding and lamination. The corresponding battery structure forms are mainly cylindrical, square and soft pack. Cylindrical and square batteries are mainly produced by winding process, while soft pack batteries are mainly produced by lamination process. The cylindrical batteries are mainly represented by 18650 and 26650 (Tesla has independently developed 21700 batteries and is promoting them throughout the industry). The difference between the square and soft pack batteries is that the outer shells are made of hard aluminum shells and aluminum-plastic films, respectively. The soft packs are mainly based on the lamination process, while the aluminum shells are mainly based on the winding process.

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

　　Since the winding process can achieve high-speed production of battery cells through the rotation speed, and the speed that can be increased by the lamination technology is limited, the current domestic power AAA rechargeable battery mainly use the winding process, so the shipment volume of the winding machine is currently greater than that of the lamination machine.

　　The front-end processes corresponding to the winding and lamination production are the production and die-cutting of the pole piece. The production process includes welding the slit pole piece/ear piece, dust removal of the pole piece, application of protective tape, rubber coating of the ear piece, and winding or cutting to a fixed length. The winding pole piece is used for the subsequent fully automatic winding, and the fixed length cutting pole piece is used for the subsequent semi-automatic winding; the punching pole piece is to roll and punch the slit pole piece for the subsequent lamination process.

　　In terms of lithium battery packaging and welding, the mainstream laser technology integration application manufacturers such as Lianying, Daju, and Guangda are all involved, which can meet the needs and do not need to be imported.

　　Lithium battery back-end process flow: capacity division and formation are the core links

　　The lithium battery back-end production process mainly includes four processes: capacity division, formation, testing and packaging and warehousing, accounting for about 35% of the value of the production line. Formation and capacity division 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 main function of the formation process is to charge and activate the battery cell after liquid injection and packaging. The capacity division process is to test the battery capacity and other electrical performance parameters after the battery is activated and graded. The formation and capacity division are completed by the formation machine and the capacity division machine respectively, usually by the automated capacity division formation system.

　　Lithium battery pack process: Seemingly simple but needs to be combined with systematic design

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

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

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

　　Lithium iron phosphate and ternary: Energy density is an unavoidable topic, different materials require a full set of equipment investment

　　Currently, the positive electrode materials of mainstream domestic power AAA rechargeable battery are divided into two categories: lithium iron phosphate and ternary. Among them, lithium iron phosphate is the safest lithium-ion battery positive electrode material at present, and its cycle life is usually more than 2,000 times. In addition, due to the maturity of the industry, the price and technical threshold have dropped, so many manufacturers will adopt lithium iron phosphate batteries for various reasons. However, lithium iron phosphate batteries have obvious defects in energy density. At present, the energy density of lithium iron phosphate monomer cells of BYD, the leader of lithium iron phosphate batteries, is 150Wh. By the end of 2017, BYD expects to increase the energy density to 160Wh. In theory, the energy density of lithium iron phosphate is difficult to exceed 200Gwh.

　　Ternary polymer lithium battery refers to a lithium battery whose positive electrode material uses nickel cobalt manganese oxide. The actual ratio of nickel, cobalt and manganese can be adjusted according to specific needs. Since ternary AAA rechargeable battery have higher energy density (currently, the energy density of ternary AAA rechargeable battery of first-class power battery manufacturers such as CATL can generally reach 200Wh/kg-220Wh/kg, and the industry expects that by 2020, the energy density of ternary battery cells will reach 300Wh/kg), the passenger car market has begun to turn to ternary AAA rechargeable battery, while lithium iron phosphate is more popular in buses with higher safety requirements. With the development of all-electric passenger cars, ternary AAA rechargeable battery 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 two are roughly the same in production process flow, 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 production capacity is high (ternary materials have strict requirements on vacuum dehumidification, etc., and the previous lithium iron phosphate production line basically has no dehumidification requirements), so many battery cell factories will simultaneously layout and purchase equipment separately in capacity planning.

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