According to Coating Online, the differences mainly stem from different equipment suppliers and varying import/domestic ratios. The basic process flow remains the same, and while there are deviations in the value proportions, they generally conform to the expected ratio.
The main lithium battery production equipment used in the front-end processes includes vacuum mixers, coating machines, and rolling mills; the mid-end processes mainly include die-cutting machines, winding machines, stacking machines, and liquid injection machines; and the back-end processes include formation machines, capacity testing equipment, and automated process warehousing and logistics. In addition, battery pack production also requires automated pack manufacturing equipment.
Lithium-ion battery front-end manufacturing process: Electrode manufacturing is crucial to core battery performance
The result of the front-end process of lithium batteries is the preparation of the positive and negative electrode sheets. The first step is stirring, which involves mixing the positive and negative solid battery materials evenly, adding a solvent, and stirring into a slurry using a vacuum mixer. The stirring of the materials is the foundation of subsequent lithium battery processes, and high-quality stirring is the basis for the high-quality completion of subsequent coating and rolling processes.
Following coating and rolling processes comes slitting, which involves cutting the coated material. If burrs are generated during slitting, they can pose safety hazards in subsequent assembly, electrolyte injection, and even during battery use. Therefore, front-end equipment in lithium battery production, such as mixers, coating machines, rolling mills, and slitting machines, are core machines in battery manufacturing, affecting the quality of the entire production line. Consequently, the value (amount) of front-end equipment accounts for the highest proportion of the entire automated lithium battery production line, approximately 35%.
Lithium-ion battery mid-stage process flow: Efficiency first, winding precedes stacking.
In the lithium battery manufacturing process, the mid-stage process mainly completes the battery forming. The main process flow includes sheet making, electrode winding, die cutting, cell winding and forming, and stacking. This is currently a highly competitive area for domestic equipment manufacturers, accounting for about 30% of the value of lithium battery production lines.
Currently, there are two main manufacturing processes for power lithium-ion battery cells: winding and stacking. The corresponding battery structures are mainly cylindrical, prismatic, and pouch cells. Cylindrical and prismatic batteries are primarily produced using the winding process, while pouch cells mainly use the stacking process. Cylindrical cells are mainly represented by the 18650 and 26650 (Tesla has developed the 21700 battery separately and is promoting it across the industry). The difference between prismatic and pouch cells lies in the outer casing: one uses a hard aluminum shell, and the other uses an aluminum-plastic film. Pouch cells primarily use the stacking process, while aluminum shells primarily use the winding process.
According to Coating Online, soft-pack batteries primarily target the mid-to-high-end digital market, offering higher profit margins per unit. Under the same production capacity, their relative profit is higher than that of aluminum-cased batteries. Because aluminum-cased batteries are easier to scale up, and product qualification rates and costs are easier to control, both currently enjoy considerable profits in their respective market segments. In the foreseeable future, neither is likely to be completely replaced.
Since the winding process can achieve high-speed cell production through rotational speed, while the stacking technology can only improve speed to a limited extent, the domestic power lithium battery currently mainly adopts the winding process. Therefore, the shipment volume of winding machines is currently greater than that of stacking machines.
The preceding processes for winding and stacking production are electrode sheet preparation and die-cutting. Electrode sheet preparation includes welding the slit electrode sheets/tabs, dust removal from the electrode sheets, applying protective tape, coating the tabs with adhesive, and winding or cutting to a fixed length. The wound electrode sheets are used for subsequent fully automatic winding, while the cut electrode sheets are used for subsequent semi-automatic winding. Die-cut electrode sheets are formed by die-cutting the slit electrode sheets after winding, and are used for subsequent stacking processes.
In the field of lithium battery packaging and welding, mainstream laser technology integration and application manufacturers such as Lianying, Han's Laser, and Everbright are all involved, which can meet the needs and eliminate the need for imports.
The core process of lithium battery back-end manufacturing is capacity testing and formation.
The main downstream production process of lithium batteries consists of four steps: capacity grading, formation, testing, and packaging/warehousing, accounting for approximately 35% of the production line's value. Formation and capacity grading are the most crucial downstream processes, activating and testing the formed batteries. Due to the long charge-discharge testing cycle, the equipment used in these processes has the highest value. The main function of the formation process is to activate the electrolyte-filled and packaged cells by charging, while the capacity grading process tests the battery's capacity and other electrical performance parameters after activation and performs grading. Formation and capacity grading are typically completed by automated capacity grading and formation systems, with formation machines and capacity grading machines respectively.
Lithium-ion battery pack manufacturing process: seemingly simple but requires integration with system design.
A power battery pack system is a battery pack that connects numerous individual cells in series and parallel, integrating battery hardware systems such as power and thermal management. The 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 application. The design requirements are usually put forward by cell manufacturers or car manufacturers, and are usually completed by battery manufacturers, car manufacturers, or third-party pack manufacturers.
Lithium-ion battery pack production lines are relatively simple, with core processes including material loading, bracket bonding, welding, and testing. The core equipment consists of laser welding machines and various bonding and testing devices. According to Coating Online, major lithium-ion battery equipment manufacturers currently have limited automation integration in this field, while laser equipment manufacturers such as Han's Laser and Lianying Laser have a high market share in pack equipment due to their absolute advantage in the laser field.
Lithium iron phosphate and ternary lithium batteries: Energy density is an unavoidable topic, and different materials require a complete set of equipment investment.
Currently, the mainstream cathode materials for power lithium batteries in China are divided into two main categories: lithium iron phosphate (LFP) and ternary lithium batteries. LFP is currently the safest cathode material for lithium-ion batteries, with a cycle life typically exceeding 2000 cycles. Furthermore, the maturity of the industry has led to lower prices and reduced technological barriers, causing many manufacturers to adopt LFP batteries for various reasons. However, LFP batteries have a significant drawback in terms of energy density. Currently, BYD, a leading LFP battery manufacturer, has an energy density of 150Wh for a single LFP cell, and BYD plans to increase this to 160Wh by the end of 2017. Theoretically, it is difficult for the energy density of LFP to exceed 200GWh.
Ternary polymer lithium batteries refer to lithium batteries that use nickel-cobalt-manganese lithium oxide as the cathode material. The actual ratio of nickel, cobalt, and manganese can be adjusted according to specific needs. Because ternary lithium batteries have higher energy density (currently, the energy density of ternary lithium batteries from leading power battery manufacturers such as CATL generally reaches 200Wh/kg-220Wh/kg, and the industry predicts that by 2020, the energy density of a single ternary battery cell will reach 300Wh/kg), the passenger vehicle market is beginning to shift towards ternary lithium batteries. However, in buses with higher safety requirements, lithium iron phosphate batteries are more favored. With the development of all-electric passenger vehicles, ternary lithium batteries are occupying an increasingly important position.
The two materials differ in energy density and cost, leading to different choices for different automobiles and automakers. According to Coating Online, their production processes are largely the same, with the main differences lying in the materials used and their proportions, significant variations in specific process parameters, and the inability to produce on the same production line. Furthermore, simply modifying and switching production capacity is costly (ternary materials have strict requirements for vacuum dehumidification, while previous lithium iron phosphate production lines had virtually no dehumidification requirements). Therefore, multiple battery cell manufacturers plan to simultaneously deploy and separately procure equipment in their capacity planning.
