lithium battery

Lithium-ion battery is a complex system including positive electrode, negative electrode, diaphragm, electrolyte, collector, binder, conductive agent and so on. The reactions involved include electrochemical reactions of positive and negative electrodes, lithium ion conduction and electron conduction, and heat diffusion. The production process of lithium battery is long, involving more than 50 processes.

Lithium batteries can be divided into cylindrical batteries, square batteries and soft pack batteries according to their forms, and their production processes are somewhat different, but overall the lithium manufacturing process can be divided into the front section of the process (electrode manufacturing),best lithium ion battery machine company the middle section of the process (core synthesis), and the back section of the process (chemical encapsulation). Due to the high safety performance requirements of lithium-ion batteries, so the battery manufacturing process of lithium equipment precision, stability and automation level are extremely high requirements.

Lithium equipment is a kind of equipment that can manufacture materials such as positive and negative electrode materials, diaphragm materials and electrolyte in an orderly manner, which is one of the decisive for lithium battery assembly According to the different process flow, lithium equipment can be divided into the front part of the equipment, the middle part of the equipment and the back part of the equipment.

The production goal of the front section process is to complete the manufacture of (positive and negative) pole pieces. The main processes in the front section process are: mixing, coating, roller pressing, slitting, making, die cutting, and the equipment involved mainly includes: mixer, coating machine, roller press, slitter, making machine, die cutting machine, etc.

Slurry mixing (equipment used: vacuum mixer) is to mix the positive and negative solid battery materials evenly and then add solvents to mix into a slurry. Slurry mixing is the starting point of the first section of the process, and is the prelude to the completion of the subsequent coating, roller pressing and other processes.

Coating (equipment used: coating machine) is to evenly coat the stirred slurry on the metal foil and dry it to make positive and negative electrode wafers. As the core link of the previous process, the execution quality of the coating process profoundly affects the consistency, safety and life cycle of the finished battery, so the coating machine is the most valuable equipment in the previous process.

Roller pressing (equipment used: roller press) is to further compact the coated pole piece, so as to improve the energy density of the battery. The degree of flatness of the pole piece after rolling will directly affect the processing effect of the subsequent slitting process, and the uniformity of the active substance of the pole piece will also indirectly affect the performance of the battery cell.

Slitting (equipment used: slitter) is the continuous longitudinal cutting of a wide roll of poles into a number of narrow pieces of the required width. Pole piece in the slitting encountered shear fracture failure, slitting edge flatness (no burr, no flexing) is the key to examine the performance of the slitting machine.

Sheet making (equipment used: sheet making machine) includes welding lugs on the slit poles, applying protective tape, wrapping the lugs with adhesive, or using laser cutting to form the lugs, etc., so as to be used in the subsequent winding process. Die-cutting (equipment used: die-cutting machine) is the process of punching and cutting the coated poles into shape for use in subsequent processes.

The production goal of the intermediate stage process is to complete the manufacturing of the battery. There are differences in the technical routes and production equipment for different types of lithium battery intermediate processes. The essence of the intermediate process is the assembly process, specifically the orderly assembly of the (positive and negative) pole pieces made in the previous process with the diaphragm and electrolyte. Due to the different energy storage structures of square (rolled), cylindrical (rolled) and flexible (laminated) batteries, there are obvious differences in the technical routes and production equipment of different types of lithium batteries in the intermediate process. Specifically, the main processes in the intermediate process of square and cylindrical batteries are winding, liquid injection and packaging, involving equipment mainly winding machines, liquid injection machines and packaging equipment (shelling machines, slot rolling machines, sealing machines and welding machines). The main processes in the intermediate stage of flexible batteries are lamination, liquid injection and packaging, and the equipment involved mainly includes laminating machines, liquid injection machines and packaging equipment.

Winding (equipment used: winding machine) is the production process or winding die-cutting machine to produce the pole piece winding into lithium-ion battery cells, mainly used for square, round lithium battery production. Winding machine can be subdivided into two categories: square winding machine and cylindrical winding machine, which are used in the production of square and cylindrical lithium batteries respectively. Compared with cylindrical winding, square winding process requires higher tension control, so square winding machine is more technically difficult.

Stacking (equipment used: stacking machine) is the die-cutting process of monomer pole pieces made into lithium-ion battery cells, mainly used for soft pack battery production. Compared with square and cylindrical cells, soft pack cells have obvious advantages in energy density, safety, discharge performance and other aspects. However, the stacking machine to complete a single stacking task, involving a number of sub-processes in parallel with the complex mechanism of synergy, to improve the stacking efficiency need to deal with the complex dynamics of the control problem; while the winding machine speed and winding efficiency directly linked to the efficiency of the means of increasing efficiency is relatively simple. At present, there is a gap between the production efficiency and yield rate of stacked batteries and wound batteries.

Liquid injection machine (equipment used: liquid injection machine) is to quantitatively inject the electrolyte of the battery into the electric core.

Core encapsulation (technical equipment used: shelling machine, rolling groove machine, sealing machine, welding machine) is to put the coiled core into the core shell.

The production goal of the latter process is to complete the chemical encapsulation. As of the middle process, the functional structure of the lithium battery core has been formed, and the significance of the latter process is to activate it, and after testing, sorting and assembling, to form a finished product of lithium battery with safe use and stable performance. The main processes in the latter part of the process are: formation, capacity, testing, sorting, etc. The equipment involved mainly includes: charging and discharging machine, testing equipment, etc.

Formation (equipment used: charge/discharge machine) is activated by the first charging of the battery cell, the formation of effective passivation film on the surface of the negative electrode (SEI film) in the process of achieving the lithium battery "initialization". The secondary capacity (equipment used: charger/discharger) is the "analyzed capacity", which is converted to a battery according to the charge/discharge design criteria, in order to measure the capacity of the battery. The charging and discharging process of the battery takes place throughout the formation and distribution of the battery's capacity, so the charger/discharger is the most commonly used back-end core device. The smallest unit of the charger/discharger is the "channel", a "unit" (BOX) by a number of "channel" combined, multiple "units A "unit" (BOX) consists of several "channels", and several "units" are combined to form a charger/discharger.

Detection (equipment used: testing equipment) in the charging, discharging, static before and after are to be carried out; sorting is based on the test results of the chemical into, after the separation of the battery according to certain standards for classification and selection. The significance of the testing and sorting process is not only to exclude substandard products, due to the practical application of lithium-ion batteries, cells are often combined in parallel and series, so the selection of close to the performance of the cell, which helps to optimize the overall performance of the battery.

Lithium battery production is inseparable from the lithium battery production equipment, in addition to the materials used in the battery itself, the manufacturing process and production equipment is an important factor in determining the performance of the battery.

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