Low-temperature annealing system and low-temperature annealing method

Abstract

The invention discloses a low-temperature annealing system and a low-temperature annealing method, which are used for annealing a battery piece with a metal film. The low-temperature annealing system comprises at least one annealing unit, a transmission assembly, a temperature control device, a vacuum device and a gas source. The annealing unit comprises a feeding cavity, a process cavity and a discharging cavity; the transmission assembly is used for moving the battery piece into or out of the annealing unit and transmitting the battery piece among the feeding cavity, the process cavity and the discharging cavity; the temperature control device is used for adjusting the temperature of the process cavity to realize annealing treatment and adjusting the temperature of the discharge cavity to cool the treated battery piece; the vacuum device is used for providing a vacuum environment for the annealing unit; the gas source is used for providing inert gas for the annealing unit. The vacuum device and the gas source are connected into the annealing unit, so that the oxidation risk of the metal film in the sintering process can be effectively reduced, the low-temperature annealing of the metal film is realized, and the battery performance is improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and more specifically, to a low-temperature annealing system and a low-temperature annealing method. Background Art

[0002] For different battery structures such as Passivated Emitter and Rear Contact (PERC), Tunneling Oxide Passivated Contact Solar Cells (Topcon), and Back Contact Cells (BC) technologies, the outer film layers of the battery are all made of insulating materials. In order to form a good ohmic contact between the battery grid line and the silicon material of the battery, a high-temperature sintering method is required to "burn through" the insulating material on the surface of the battery, so that the grid line directly contacts the silicon material, thereby achieving an effective connection. In traditional processes, silver paste is usually used to make the grid line, and high-temperature sintering is used to "burn through" the insulating material of the silver grid line, so that the silver grid line directly contacts the silicon material.

[0003] With the continuous development of photovoltaic cells, competition in photovoltaic cell manufacturing costs continues to intensify. Silver paste has long accounted for a significant portion of the battery metallization process. Silver resources are limited, and its price continues to rise, making the substitution of copper for silver a hot topic in the industry. However, copper is more susceptible to oxidation than silver, increasing the difficulty and complexity of the battery metallization process and significantly increasing process costs. Consequently, existing annealing equipment suitable for sintering silver paste is difficult to adapt to sintering copper paste. Summary of the Invention

[0004] In view of this, the present application provides a low-temperature annealing system and a low-temperature annealing method for annealing battery cells with metal films, which can effectively reduce the annealing temperature, realize low-temperature annealing of the metal film, reduce the risk of oxidation of the metal film during the annealing process, and effectively reduce costs; in addition, the low-temperature annealing system can effectively shorten the production line length, which is conducive to reducing the footprint.

[0005] In a first aspect, an embodiment of the present application provides a low-temperature annealing system, which includes: a plurality of annealing units arranged in parallel, a transmission component, a temperature control device, a vacuum device, and a gas source. The annealing unit includes a feed chamber, a process chamber and a discharge chamber. The feed chamber, the process chamber and the discharge chamber can be interconnected or isolated from each other, and the feed chamber and the discharge chamber can be connected to or isolated from the outside world. The annealing unit is used to anneal the battery cells provided with base metal slurry to form electrodes; the transmission component is used to move the battery cells into or out of the multiple annealing units, and to transfer the battery cells between the feed chamber, the process chamber and the discharge chamber; the temperature control device includes a first temperature control component located in the process chamber and a second temperature control component located in the discharge chamber, the first temperature control component is used to heat the process chamber, and the second temperature control component is used to cool the discharge chamber; a vacuum device is connected to the annealing unit, and the vacuum device is used to provide a vacuum environment for the annealing unit; a gas source is connected to the annealing unit, and the gas source is used to provide flowing inert gas to the annealing unit.

[0006] In this application, an annealing unit is connected through a vacuum device and a gas source, a vacuum environment is provided for the annealing unit through the vacuum device, and a flowing inert gas is provided for the annealing unit through the gas source. With the cooperation of the two, the oxidation risk of the metal film during the sintering process can be effectively reduced, the uniformity of annealing can be improved, low-temperature annealing of the metal film can be achieved, and battery performance can be improved; moreover, the vacuum environment can greatly reduce the use of inert gases such as nitrogen, thereby reducing costs.

[0007] As a possible implementation manner, the feed chamber and the discharge chamber are the same chamber, the annealing unit includes a plurality of process chambers, and the feed chamber is located between the plurality of process chambers.

[0008] As a possible implementation, the transport assembly includes: a first transport mechanism, a second transport mechanism, and a transfer mechanism. The first transport mechanism is located outside the annealing unit and is used to move the cell to or from the outside of the feed chamber; the second transport mechanism is located inside the annealing unit and is used to drive the cell to transfer between the feed chamber and the plurality of process chambers; and the transfer mechanism is located above the feed chamber and the first transport mechanism and is used to transfer the cell between the first and second transport mechanisms.

[0009] As a possible implementation manner, the low-temperature annealing system includes a plurality of the annealing units arranged in parallel, and a first transmission mechanism and a transfer mechanism are provided between two adjacent annealing units.

[0010] As a possible implementation method, the low-temperature annealing system includes a plurality of annealing units arranged side by side, and the plurality of annealing units share the same feed chamber and the same discharge chamber. The feed chamber and the discharge chamber are respectively located at opposite ends of the process chamber. Along the first direction from the feed chamber to the discharge chamber, the process chamber includes a plurality of second chambers connected in series.

[0011] As a possible implementation, the vacuum device includes a first vacuum component and a second vacuum component. The first vacuum component is connected to the process chamber to provide a vacuum environment for the process chamber; the second vacuum component is respectively connected to the feed chamber and the discharge chamber to provide a vacuum environment for the feed chamber and the discharge chamber.

[0012] As a possible implementation, the process chamber includes a preheating zone and a constant temperature zone that are interconnected, and the temperature gradient of the preheating zone increases along the direction from the preheating zone to the constant temperature zone.

[0013] As a possible implementation, the low-temperature annealing system further includes a circulation device communicated with the discharge chamber, and the circulation device is used to cool and recycle the inert gas discharged from the discharge chamber.

[0014] As a possible implementation, each process chamber has a plurality of processing areas arranged in parallel along a direction perpendicular to the transmission direction of the battery slices, and a flow equalizer is provided between two adjacent processing areas.

[0015] As a possible implementation, the second temperature control component includes cooling coils distributed around the discharge cavity, and coolant is provided in the cooling coils.

[0016] In the second aspect, an embodiment of the present application provides a low-temperature annealing method, including: transferring a first battery cell to be processed to an inlet and outlet chamber, and vacuuming the inlet and outlet chamber; connecting the inlet and outlet chamber and a first process chamber in a vacuum state, and transferring the first battery cell to the first process chamber; heating the first process chamber, and injecting flowing inert gas into the first process chamber to anneal the first battery cell; in the process of annealing the first battery cell in the first process chamber, connecting the second process chamber and the inlet and outlet chamber, and transferring the second battery cell annealed in the second process chamber to the inlet and outlet chamber for cooling; after cooling, injecting inert gas into the inlet and outlet chamber to the atmospheric environment, and moving the annealed second battery cell out of the inlet and outlet chamber.

[0017] Conventional annealing processes are mostly high-temperature annealing processes performed at atmospheric pressure, using chain furnaces with long production lines. Driven by the chain, individual carriers are heated in a step-by-step manner, resulting in low annealing efficiency and poor annealing results. Furthermore, these processes are usually open-type, and the metal films used for processing (such as silver paste films) are not easily oxidized in an oxygen environment. Clearly, this type of annealing equipment cannot be used for annealing oxygen-sensitive metal materials.

[0018] The annealing process of the present application is to evacuate the inlet and outlet chambers and the process chamber, and at the same time, a flowing inert gas (such as nitrogen) is injected into the chamber in conjunction with a gas source, which can effectively reduce the oxidation of metal materials (such as copper) that are sensitive to oxygen. At the same time, the vacuum environment can greatly reduce the amount of nitrogen used, reducing costs. Moreover, in the annealing process of the present application, the carrier is stationary in the process chamber, and the inlet and outlet inert gases remain in a flowing state (such as lateral convection). The thermal field is more uniform, and the metal film can be fully annealed, which is beneficial to reduce the diffusion or penetration of the metal at high temperatures and improve the performance of the battery. The inert gas flowing during the cooling process can also make the cooling more uniform, further improving the performance of the battery. In addition, the annealing temperature of the annealing process of the present application can also achieve a gradient temperature design to further improve the annealing effect. The low-temperature annealing process of the present application is simple in process, and the inlet and outlet chambers are designed with multiple process chambers, which can make full use of the inlet and outlet chambers and the process chamber, effectively improve the annealing efficiency, make rational use of space, have low costs, and avoid the conventional lengthy and high-temperature sintering process.

[0019] As a possible implementation, during the annealing process of the battery cell, the battery cell is stationary in the process chamber, and the annealing process includes a gradient temperature control process, which includes a temperature rise stage and a constant temperature stage.

[0020] As a possible implementation, during the cooling process, the method further includes: cooling the inert gas in the inlet and outlet cavity and recycling it.

[0021] In a third aspect, an embodiment of the present application provides another low-temperature annealing method, comprising: transferring a plurality of battery cells to be processed to a feed chamber, and evacuating the feed chamber; connecting the feed chamber and a plurality of process chambers in a vacuum state and arranged side by side, and transferring the plurality of battery cells to the plurality of process chambers respectively; heating the plurality of process chambers, and injecting flowing inert gas into the plurality of process chambers to anneal the plurality of battery cells respectively; connecting the plurality of process chambers and a discharge chamber in a vacuum state, and transferring the plurality of battery cells after annealing to the feed chamber and discharge chamber for cooling, and injecting flowing inert gas into the discharge chamber during the cooling process; and, after the cooling is completed, injecting inert gas into the discharge chamber to the atmospheric environment, and moving the battery cells after annealing out of the discharge chamber.

[0022] Compared with the above embodiment, the low temperature annealing method of this embodiment can achieve continuous annealing, which can further improve the annealing efficiency. In addition, the annealing method of this embodiment can also design multiple process chambers in series according to the process cycle requirements.

[0023] As a possible implementation, during the cooling process, the method further includes: cooling the inert gas in the discharge chamber and recycling it.

[0024] As a possible implementation method, along the first direction of the feed chamber toward the discharge chamber, the process chamber includes a first chamber and a second chamber connected in series. In the step of annealing the battery cell, the method includes: driving the battery cell into the first chamber and the second chamber in sequence for annealing, wherein along the first direction, the temperature gradient in the first chamber increases, and the temperature in the second chamber remains constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a hardware framework diagram of a low-temperature annealing system according to an embodiment of the present application.

[0026] Figure 2 This is a top view of a partial structure of a low-temperature annealing system according to an embodiment of the present application.

[0027] Figure 3 This is a side view of the corresponding inlet and outlet chambers in the low-temperature annealing system according to one embodiment of the present application.

[0028] Figure 4 Schematic diagram of the structure of a carrier board according to an embodiment of the present application.

[0029] Figure 5 This is a structural diagram of a carrier frame according to an embodiment of the present application.

[0030] Figure 6Schematic diagram of the structure of a process chamber according to an embodiment of the present application.

[0031] Figure 7 FIG. 1 is a side view of a single process chamber according to an embodiment of the present application.

[0032] Figure 8 This is a side view of a single inlet and outlet cavity according to an embodiment of the present application.

[0033] Figure 9 This is a hardware framework diagram of a low-temperature annealing system according to another embodiment of the present application.

[0034] Figure 10 This is a top view of a partial structure of a low-temperature annealing system according to another embodiment of the present application.

[0035] Figure 11 A side view of two process chambers arranged side by side according to an embodiment of the present application.

[0036] Figure 12 This is a side view of two parallel feeding and discharging cavities according to an embodiment of the present application.

[0037] Figure 13 This is a flow chart of a low temperature annealing method according to an embodiment of the present application.

[0038] Figure 14 This is a flow chart of a low temperature annealing method according to another embodiment of the present application.

[0039] Description of main component symbols:

[0040] Low temperature annealing system 100,200 tray 71 Annealing unit 10,10a Discharge cavity 8 Transmission components 1,1a Isolation door 9 First transmission mechanism 11 Temperature control device 20 Second transmission mechanism 12 First temperature control component 201 Transfer institution 13 Second temperature control component 202 Inlet and outlet cavity 2 Vacuum device 30 heat sink 23 First vacuum assembly 301 process chamber 3,3a Second vacuum assembly 302 Processing Area 31,21 Gas source 40 Flow plate 32,22 Carrier 50 Preheating area 33 frame 501 Constant temperature zone 34 slots 502 First cavity 35 case 60 Second cavity 36 Circulation device 70 air intake 37 Circulation pump 701 exhaust port 38 heat exchanger 702 Feed cavity 4 Circulation pipeline 703 Loading position 5 First direction X Unloading position 6 Second direction Y carrier board 7 vertical direction Z

[0041] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0042] Because copper easily oxidizes at the nanoscale, it can typically only be used within extremely short processing times, which increases the difficulty of the actual sintering process. Furthermore, if copper paste is sintered using existing high-temperature sintering processes, the high sintering temperature causes copper elements to easily diffuse and penetrate the cell, forming deep energy-level centers that destroy the passivation effect and affect battery performance. Therefore, existing high-temperature sintering processes are difficult to apply to copper paste processes.

[0043] The inventors of this application have discovered that to prevent copper oxidation and copper diffusion and penetration on the cell at high temperatures, electrodes can be fabricated in two steps: first, a "seed layer" is formed on the cell at high temperature to burn through the insulating material and establish good contact with the silicon material; then, a copper paste is applied to the surface of the seed layer and a low-temperature sintering process is used to form the copper layer. Furthermore, low-temperature sintering of copper paste requires an oxygen-free or low-oxygen sintering furnace, and cannot be used in furnaces similar to those used to sinter silver paste.

[0044] To do this, see Figure 1 and Figure 2 One embodiment of the present application provides a low-temperature annealing system 100 for solar cells, which is used to anneal cells with base metal thin films to form electrodes. The low-temperature annealing system 100 includes at least one annealing unit 10, a transport assembly 1, a temperature control device 20, a vacuum device 30, and a gas source 40. The transport assembly 1 can move unannealed cells into and out of the annealing unit 10, which anneals the base metal thin films on the cells to form electrodes.

[0045] The annealing unit 10 includes a feed chamber, a discharge chamber, and multiple process chambers 3, which can be interconnected or isolated. The temperature control device 20 includes a first temperature control assembly 201 located within the process chamber 3 and a second temperature control assembly 202 located within the discharge chamber. The first temperature control assembly 201 heats the process chamber 3 to the desired annealing temperature. The second temperature control assembly 202 cools the discharge chamber to cool the annealed cells.

[0046] The vacuum device 30 is capable of regulating the vacuum level within the annealing unit 10, providing a low-oxygen vacuum environment for the annealing process. Specifically, the vacuum device 30 comprises a first vacuum assembly 301 and a second vacuum assembly 302. The first vacuum assembly 301 communicates with the process chamber 3, providing a vacuum environment there. The second vacuum assembly 302 communicates with the feed chamber and discharge chamber, respectively, providing a vacuum environment there. Since the process chamber 3 remains in a vacuum state throughout the annealing process and does not require direct communication with the outside world, independent control by the first vacuum assembly 301 facilitates precise regulation of the vacuum level in the process chamber 3. However, the vacuum level in the feed chamber and discharge chamber varies significantly during the loading and unloading process and requires communication with the outside world. Independent vacuum control by the second vacuum assembly 302 facilitates vacuum control. Furthermore, the first vacuum assembly 301 is also connected to a combustion tower, allowing the organic waste gas generated during the annealing process to be drawn to the combustion tower for combustion and then routed to the plant's organic waste gas discharge system. In some embodiments, when the annealing unit 10 includes multiple process chambers 3, the first vacuum assembly 301 can be connected to the multiple process chambers 3 through pipelines to independently control the multiple process chambers 3, or to control them in a coordinated manner. In some embodiments, the second vacuum assembly 302 can be connected to the feed chamber and the discharge chamber through pipelines to perform vacuum control on the feed chamber and the discharge chamber.

[0047] The gas source 40 can provide a small amount of flowing inert gas to the annealing unit 10. The flowing inert gas can realize gas convection in the annealing unit 10, making the thermal field more uniform, and can improve the temperature uniformity in the annealing unit 10, thereby improving the uniformity of battery cell annealing and improving battery performance.

[0048] The low-temperature annealing system 100 may include a plurality of annealing units 10 arranged in parallel. The plurality of annealing units 10 can be independently controlled, so that one or more of them can be flexibly selected to be opened according to actual needs. When a plurality of annealing units 10 are opened at the same time, the annealing efficiency can be effectively improved. Moreover, the plurality of annealing units 10 arranged in parallel can also shorten the length of the production line and reduce the space occupied by the workshop.

[0049] In some possible embodiments, the base metal material may be selected from at least one of copper (Cu), nickel, chromium, lead, aluminum, or silver-clad copper.

[0050] See also Figure 2The low-temperature annealing system 100 also includes a loading position 5 and a unloading position 6 provided at opposite ends of the transmission component 1. The loading position 5 is used to temporarily store cells that have not been annealed, and the unloading position 6 is used to temporarily store cells that have been annealed. The annealing unit 10 can be located between the loading position 5 and the unloading position 6. The transmission component 1 can transfer the cells on the loading position 5 to the annealing unit 10 for annealing, and can also transfer the cells that have been annealed in the annealing unit 10 to the unloading position 6. The loading position 5 and the unloading position 6 are arranged at opposite ends of the transmission component 1, which can facilitate the connection of the low-temperature annealing system 100 to the process line of the solar cell. The loading position 5 can be connected to the previous process of the process line, and the unloading position 6 can be connected to the next process of the process line. It is understandable that the loading position 5 and the unloading position 6 can also be at the same position, which can further reduce the space occupied. In addition, the positions of the loading position 5 and the unloading position 6 can be flexibly set according to the actual site to make full use of the space.

[0051] In some possible embodiments of this application, please refer to Figure 2 The annealing unit 10 includes a feed chamber, a discharge chamber and a plurality of process chambers 3 that can be interconnected or isolated from each other. In this embodiment, the feed chamber and the discharge chamber are the same cavity, which is named as the feed chamber 2. The feed chamber 2 and the plurality of process chambers 3 can be interconnected or isolated from each other, that is, an isolation door 9 is provided between the feed chamber 2 and each process chamber 3, and the connection or isolation between the two adjacent chambers is achieved by opening and closing the isolation door 9. At the same time, the feed chamber 2 can also be connected to or isolated from the outside world to facilitate the entry and exit of the battery cells. The feed chamber 2 integrates the functions of the feed chamber and the discharge chamber, and can realize the feeding and cooling and discharging of the battery cells. In some embodiments, the inlet and outlet chamber 2 can be located between multiple process chambers 3, that is, multiple process chambers 3 can be arranged around the inlet and outlet chamber 2, and an isolation door 9 can be set between the inlet and outlet chamber 2 and each process chamber 3. Multiple process chambers 3 can be controlled independently, so that the same inlet and outlet chamber 2 can be fully utilized to realize the inlet and outlet of multiple process chambers 3, thereby improving the utilization rate and annealing efficiency of the inlet and outlet chamber 2 and the process chamber 3, and reducing the space occupied. In addition, the inlet and outlet share one cavity, reducing the design of one cavity and reducing the cost.

[0052] See also Figure 2 and Figure 3The transmission assembly 1 includes a first transmission mechanism 11, a second transmission mechanism 12 and a transfer mechanism 13. The first transmission mechanism 11 is located outside the annealing unit 10, and is used to move the battery cells to or away from the outside of the inlet and outlet chamber 2. In some embodiments, the loading position 5 and the unloading position 6 are respectively located at both ends of the transmission path of the first transmission mechanism 11. The first transmission mechanism 11 can move the battery cells from the loading position 5 to the outside of the inlet and outlet chamber 2, or move the battery cells from the outside of the inlet and outlet chamber 2 to the unloading position 6. The second transmission mechanism 12 is located inside the annealing unit 10, and is used to drive the battery cells to transfer between the inlet and outlet chamber 2 and multiple process chambers 3. The transfer mechanism 13 is located above the inlet and outlet chamber 2 and the first transmission mechanism 11. The transfer mechanism 13 is used to transfer the battery cells between the first transmission mechanism 11 and the second transmission mechanism 12 in the inlet and outlet chamber 2.

[0053] Combine Figure 2 and Figure 3 According to the setting position of the loading position 5 and the unloading position 6, the transmission path of the first transmission mechanism 11 can be a straight path or a curved path. In some embodiments, the transmission path of the first transmission mechanism 11 is a straight line extending along the first direction X, and the loading position 5 and the unloading position 6 are respectively located at opposite ends of the transmission path, then the annealing unit 10 is located on one side of the first transmission mechanism 11, so that the transmission direction of the transfer mechanism 13 (defined as the second direction Y) is perpendicular to the first direction X. The second transmission mechanism 12 is located inside the annealing unit 10 and can be set according to the relative position relationship between the process chamber 3 and the inlet and outlet chamber 2. In some embodiments, the annealing unit 10 includes two process chambers 3 and one inlet and outlet chamber 2. Along the first direction X, the two process chambers 3 are respectively located on opposite sides of the inlet and outlet chamber 2. In this way, the second transmission mechanism 12 extends along the first direction X to realize the transmission of the battery cells between the two process chambers 3 and the inlet and outlet chamber 2.

[0054] Please refer again Figure 3 The low-temperature annealing system 100 may further include a shell 60. The transmission component 1 and the annealing unit 10 may be wholly or partially located inside the shell 60. The first transmission mechanism 11 is located at the bottom of the shell 60, and the transfer mechanism 13 is located at the top of the shell 60. Through the cooperation of the first transmission mechanism 11 and the transfer mechanism 13, the transmission and transfer of the battery cells in and out of the annealing unit 10 can be realized.

[0055] In some embodiments, the first transmission mechanism 11 may be a transmission belt line, the transfer mechanism 13 may be a robotic arm, and the second transmission mechanism 12 may be a transmission roller.

[0056] Please refer again Figure 2 and Figure 3As shown, the low-temperature annealing system 100 may include a plurality of annealing units 10 arranged in parallel, and two adjacent annealing units 10 may share a first conveying mechanism 11 and a transfer mechanism 13. In some embodiments, the low-temperature annealing system 100 includes two annealing units 10 arranged in parallel, each annealing unit 10 includes two process chambers 3 and an inlet and outlet chamber 2, the first conveying mechanism 11 is located between the two annealing units 10, and can transfer the battery cell from the loading position 5 to the outside of the inlet and outlet chamber 2, the transfer mechanism 13 is located above the two inlet and outlet chambers 2 and the first conveying mechanism 11, and can grab the battery cell from the first conveying mechanism 11 and transfer it to any of the inlet and outlet chambers 2, and each annealing unit 10 is provided with a second conveying mechanism 12, which can transfer the battery cell between the inlet and outlet chamber 2 and the two process chambers 3.

[0057] See also Figure 4 , combined with Figure 2 The annealing unit 10 further includes a carrier plate 7, which is used to place the carrier racks 50. In some embodiments, a plurality of trays 71 are provided on the carrier plate 7, and a large number of battery cells can be placed on the carrier racks 50 in advance, and then the carrier racks 50 containing the battery cells are placed on the trays 71 of the carrier plate 7. Specifically, the plurality of trays 71 on the carrier plate 7 can be arranged in an array, so that the plurality of carrier racks 50 can be arranged in an array. The transmission component 1 can transfer the plurality of carrier plates 7 and the plurality of carrier racks 50 located on each carrier plate 7 from the loading position 5 to the annealing unit 10. The annealing unit 10 can anneal the plurality of carrier racks 50 at the same time, and then transfer them to the unloading position 6 after annealing, which effectively improves the annealing efficiency.

[0058] See also Figure 5 The figure shows a schematic diagram of the structure of an embodiment of a carrier rack 50. The carrier rack 50 is a roughly rectangular metal frame, including a frame body 501 and a plurality of slots 502 provided on the inner side of the frame body 501. The plurality of slots 502 are stacked along the height direction (or vertical direction Z) of the frame body 501. A battery cell can be placed in each slot 502. In this way, a large number of battery cells can be stacked in a carrier rack 50, and there is a certain gap between two adjacent battery cells to facilitate sufficient annealing of each battery cell. In addition, in order to allow the airflow and temperature to better contact the battery cells, no sealing plates are provided on the three sides of the frame body 501. Figure 2 A carrier rack 50 is placed on each tray 71 of the carrier plate 7. The carrier rack 50 extends along the vertical direction Z on the tray 71. Multiple battery cells are stacked and spaced apart along the vertical direction Z. Moreover, there is a certain distance between the carrier racks 50 on the multiple trays 71 arranged in an array. In this way, after entering the annealing unit 10, the airflow can fully contact each battery cell on each carrier rack 50, thereby performing annealing treatment on each battery cell.

[0059] Please refer again Figure 2 , combined with reference Figure 4 Along the second direction Y, the process chamber 3 has multiple processing zones 31 arranged in parallel, wherein the second direction Y is perpendicular to the first direction X and the vertical direction Z, that is, the second direction Y is the width direction of the second conveying mechanism 12. The carrier 7 can be transferred to the process chamber 3 by the second conveying mechanism 12. Corresponding to the multiple processing zones 31 in the process chamber 3, the carrier 7 is provided with multiple columns of trays 71, each column of trays 71 corresponding to a processing zone 31. In this way, along the first direction X, each processing zone 31 can be provided with a column of carriers 50, and multiple columns of processing zones 31 can be provided with multiple columns of carriers 50. Thus, multiple carriers 50 can be annealed simultaneously in the same process chamber 3, thereby improving annealing efficiency. In some embodiments, a flow plate 32 can be provided between two adjacent processing zones 31. During the annealing process, the flow plate 32 is located between two adjacent columns of carriers 50, which can make the airflow in the process chamber 3 flow more evenly to each carrier 50, thereby improving the uniformity of temperature distribution and improving product quality. It is understandable that a first temperature control component 201 may be provided between two adjacent processing areas 31 or on the flow plate 32 , thereby increasing the heat source and improving heating efficiency and temperature uniformity.

[0060] Please refer again Figure 2 As shown, a temperature gradient can be set within process chamber 3. This means that after the cell enters process chamber 3, it can remain stationary. Over time, the temperature within chamber 3 changes with a temperature gradient, achieving a preheating and constant temperature process to complete the cell annealing process. This temperature gradient allows the solvent in the metal film to fully evaporate, thereby improving battery performance. It also eliminates the need for a long transfer path, further reducing the space in process chamber 3.

[0061] It is understood that in other embodiments, please refer to Figure 6 Each process chamber 3 is a cavity. Moving away from the inlet and outlet chambers 2, at least one process chamber 3 includes a preheating zone 33 and a constant temperature zone 34. As it moves toward the constant temperature zone 34, the temperature gradient of the preheating zone 33 increases, ultimately approaching that of the constant temperature zone 34. This temperature gradient design allows the solvent in the metal film to fully evaporate, thereby improving battery performance. Specifically, the gradient temperature between the preheating zone 33 and the constant temperature zone 34 can be adjusted by adjusting the first temperature control assembly 201. For example, this can be achieved by adjusting the number or power of the first temperature control assemblies 201 at different locations.

[0062] See also Figure 7 , combined with Figure 2 and Figure 3The process chamber 3 is connected to a gas source 40. During the annealing process, an inert gas, such as nitrogen, can be introduced into the process chamber 3. In a vacuum environment, introducing an appropriate amount of inert gas, driven by the airflow, facilitates uniform temperature distribution within the process chamber 3, improving the annealing effect. Furthermore, a vacuum environment can significantly reduce nitrogen usage, thereby lowering costs. In some embodiments, the gas inlet of the gas source 40 is typically located on the sidewall of the process chamber 3, and the gas flow is directed along the second direction Y, i.e., the inlet and outlet gases are lateral convection, resulting in a more uniform thermal field.

[0063] Specifically, if Figure 7 As shown, the process chamber 3's air inlet 37 is located roughly in the center of the chamber's upper section, and the process chamber's air extraction ports 38 are located on opposite sides of the chamber. First temperature control components 201, such as infrared heating tubes or armored heaters, are distributed throughout the chamber. Air is extracted through the first vacuum assembly 301, which then passes through a combustion tower for treatment before being connected to the plant's service terminal. Air intake and extraction are coordinated in the roughly center of the chamber, achieving uniform cross-flow distribution, orderly gas flow, and a uniform thermal field.

[0064] In some embodiments, while introducing an inert gas, a trace amount of oxygen may also be introduced into the process chamber 3. The amount generally ranges from 0.1 ppm to 2000 ppm. For example, the amount of oxygen introduced may be 0.1 ppm, 10 ppm, 50 ppm, 100 ppm, 300 ppm, 500 ppm, 700 ppm, 1000 ppm, or any value in between. In an overall inert gas atmosphere, the introduction of a trace amount of oxygen does not cause oxidation of the metal film, but rather helps improve the annealing effect and reduce the line resistance of the printed grid lines on the surface of the cell.

[0065] See also Figure 3 As shown, refer to Figure 1 and Figure 2 The inlet and outlet chamber 2 integrates the feeding and discharging functions, and the inlet and outlet chamber 2 is connected to the second vacuum component 302 and the gas source 40. After the battery cell is transferred from the outside to the inlet and outlet chamber 2, the second vacuum component 302 can evacuate the inlet and outlet chamber 2, so that the inlet and outlet chamber 2 is in a vacuum environment. In this way, after the inlet and outlet chamber 2 and the process chamber 3 are connected, the vacuum degree in the process chamber 3 will not be affected, which is conducive to reducing the oxygen content in the process chamber 3, so as to reduce the oxidation of the metal film during the annealing process. In some embodiments, before the inlet and outlet chamber 2 is evacuated, an inert gas (such as nitrogen) can be introduced through the gas source 40. The inert gas can fully replace the air in the inlet and outlet chamber 2, and then evacuate it, which can further reduce the oxygen content on the surface of the battery cell.

[0066] It is understandable that when the first conveying mechanism 11 is disposed between the two annealing units 10, that is, the two annealing units 10 are disposed on both sides of the first conveying mechanism 11, each annealing unit 10 can be provided with a corresponding first vacuum component 301 and a second temperature control component 302 (such as Figure 2 shown).

[0067] See also Figure 2 and Figure 3 As shown, a second temperature control component 202 is provided in the inlet and outlet chamber 2. The second temperature control component 202 can cool the inlet and outlet chamber 2. When the battery cells after annealing in the process chamber 3 are transferred to the inlet and outlet chamber 2, the high-temperature battery cells can be cooled in the inlet and outlet chamber 2. After cooling, the inlet and outlet chamber 2 is filled with a sufficient amount of inert gas (such as nitrogen) to reach the atmospheric environment, and then the inlet and outlet chamber 2 can be opened to remove the annealed battery cells. It is understandable that during the cooling process, an appropriate amount of inert gas (such as nitrogen) can also be introduced into the inlet and outlet chamber 2 through the gas source 40. Under the action of the airflow, the cooling effect can be improved.

[0068] In some embodiments, the second temperature control component 202 can be a cooling coil distributed around the inlet and outlet cavity 2. The cooling coil is provided with a coolant, which can evenly cool the inlet and outlet cavity 2.

[0069] See also Figure 3 As shown, corresponding to the arrangement of the processing zones 31 in the process chamber 3, the inlet and outlet chamber 2 has a plurality of processing zones 21 arranged in parallel along the second direction Y. In some embodiments, a flow plate 22 can be provided between two adjacent processing zones 21. The flow plate 22 extends along the first direction X. A large number of through holes can be provided on the flow plate 22. During the annealing process, the flow plate 22 is located between two adjacent rows of carriers 50, which can make the airflow in the inlet and outlet chamber 2 flow more evenly to each carrier 50. In this way, during the cooling process, the cooling airflow can be evenly distributed in the inlet and outlet chamber 2, thereby improving the cooling uniformity and thus improving the cooling effect. It is understandable that a second temperature control component 202 can also be provided between two adjacent processing zones 21, or a second temperature control component 202 can be provided on the flow plate 22. For example, the second temperature control component 202 can be a cooling coil provided on the flow plate 22, thereby increasing the cooling effect.

[0070] See also Figure 8 , combined with Figure 2The low-temperature annealing system 100 further includes a circulation device 70, which is connected to the inlet and outlet chamber 2 and can recycle the inert gas in the inlet and outlet chamber 2 during the cooling and discharge process to reduce the amount of inert gas used and reduce costs. In some embodiments, the circulation device 70 includes a circulation pump 701, a heat exchanger 702, and a circulation pipeline 703 connected to the inlet and outlet chamber 2. The circulation pump 701 converts the hot gas extracted from the inlet and outlet chamber 2 into cooling nitrogen through the heat exchanger 702, and recirculates it into the inlet and outlet chamber 2 for reuse.

[0071] In some embodiments, heat exchanger 702 can contain 23°C cooling water. The nitrogen in inlet and outlet chamber 2 is driven by circulating pump 701, passing through heat exchanger 702 to remove heat from the nitrogen before recirculating into inlet and outlet chamber 2. Inlet and outlet chamber 2 also features air inlet holes and flow distribution plates on the lid and bottom of the chamber to cool the incoming air. Exhaust pipes are located on both sides of inlet and outlet chamber 2 for exhaust.

[0072] The low-temperature annealing system 100 provided in the embodiment of the present application has the following beneficial effects:

[0073] (1) The annealing unit 10 is connected through the vacuum device 30 and the gas source 40. The vacuum device provides a vacuum environment for the annealing unit, and the gas source 40 provides a flowing inert gas for the annealing unit 10. With the cooperation of the two, the oxidation risk of the metal film on the battery cell during the sintering process can be effectively reduced, the uniformity of annealing can be improved, the low-temperature annealing of the metal film can be achieved, and the battery performance can be improved. In addition, the vacuum environment can greatly reduce the use of inert gases such as nitrogen, thereby reducing costs.

[0074] (2) The feeding and discharging of the low-temperature annealing system 100 is a cavity (the feeding and discharging cavity 2), which can make full use of the same feeding and discharging cavity 2 to realize the feeding and discharging of multiple process cavities 3, thereby improving the utilization rate and annealing efficiency of the feeding and discharging cavity 2 and the process cavity 3; moreover, the length of the production line is shortened, the floor space is reduced, and the spatial layout of each cavity is more flexible; in addition, the feeding and discharging share a cavity, which reduces the design of one cavity and reduces the cost.

[0075] (3) The process chamber 3 can simultaneously perform annealing treatment on multiple battery cells on the carrier racks 50, with high annealing efficiency. Moreover, during the annealing process, the carrier racks 50 remain stationary in the process chamber 3, and the inert gas in the flowing state can achieve lateral convection, making the thermal field more uniform.

[0076] (4) The low-temperature annealing system 100 may include multiple annealing units 10 arranged in parallel. The multiple annealing units 10 can be independently controlled, so that one or more of them can be flexibly selected and activated according to actual needs. When multiple annealing units 10 are activated simultaneously, the annealing efficiency can be effectively improved. At the same time, the multiple annealing units 10 arranged in parallel and sharing a set of transmission components can also shorten the production line length and reduce the space occupied by the workshop.

[0077] (5) By providing the circulation device 70, nitrogen can be recycled during the cooling process, thereby reducing nitrogen consumption and further reducing costs.

[0078] See also Figure 9 and Figure 10 Another embodiment of the present application provides a low-temperature annealing system 200 for solar cells. The structure of the low-temperature annealing system 200 is basically the same as that of the low-temperature annealing system 100 in the aforementioned embodiment. The main difference is that the low-temperature annealing system 200 includes a transmission component 1a and an annealing unit 10a, wherein the annealing unit 10a includes a feed chamber 4, a process chamber 3a, and a discharge chamber 8 arranged in sequence, that is, the feed chamber 4 and the discharge chamber 8 are respectively located at the two ends of the process chamber 3. Among them, any two adjacent chambers of the feed chamber 4, the process chamber 3a, and the discharge chamber 8 can be interconnected or isolated from each other, that is, an isolation door 9 can be set between the above three chambers, and the connection or isolation between the two adjacent chambers can be achieved by opening and closing the isolation door 9. At the same time, the feed chamber 4 and the discharge chamber 8 can be connected to or isolated from the outside world.

[0079] See also Figure 10 The transmission component 1a is set throughout the entire annealing unit 10a. The transmission component 1a can be a continuous transmission line such as a transmission chain or a transmission roller. The annealing unit 10a also includes a loading position 5 and a unloading position 6, wherein the feed chamber 4 is arranged close to the loading position 5, and the discharge chamber 8 is arranged close to the unloading position 6, so that the loading position 5, the feed chamber 4, the process chamber 3a, the discharge chamber 8 and the unloading position 6 are arranged in sequence along the transmission direction or length direction of the transmission component 1a (defined as the first direction X). Under the drive of the transmission component 1a, the battery cell can enter the feed chamber 4, the process chamber 3a and the discharge chamber 8 in sequence from the loading position 5, and finally come out of the discharge chamber 8 to arrive at the unloading position 6 for temporary storage, or directly enter the next process from the unloading position 6.

[0080] The structure of the process chamber 3a can be substantially the same as that of the process chamber 3 in the aforementioned embodiment. Figure 10As shown, in this embodiment, the process chamber 3a can also include multiple chambers (35 and 36) connected in series, and the temperatures of the multiple chambers are increased in sequence. In some embodiments, the process chamber 3a includes two chambers, namely a first chamber 35 close to the feed chamber 4 and a second chamber 36 close to the discharge chamber 8, wherein the first chamber 35 is a preheating chamber and the second chamber 36 is a constant temperature chamber. In this way, the transmission component 1a drives the battery cell to enter the first chamber 35 in the process chamber 3a for preheating, and then enter the second chamber 36 for constant temperature. In some embodiments, the temperature in the first chamber 35 as a preheating chamber increases along the first direction X gradient, and finally the temperature of the first chamber 35 close to the second chamber 36 is close to the temperature of the second chamber 36. The gradient temperature design in the first chamber 35 can fully volatilize the solvent in the metal film, thereby improving the performance of the battery. According to actual needs, the first chamber 35 and the second chamber 36 can be directly connected, or an isolation door can be set. Specifically, the gradient temperature of the first cavity 35 and the second cavity 36 can be adjusted by adjusting the first temperature control component 201. For example, the gradient temperature setting can be achieved by adjusting the number or power of the first temperature control components 201 in different cavities and at different positions in the same cavity.

[0081] In some embodiments, the gas inlet of the gas source 40 is generally arranged on the side wall of the process chamber 3a, and the direction of the gas flow flows along the second direction Y. This is particularly suitable for a process chamber 3a with a gradient temperature setting, and can ensure that the temperature at the same position in the process chamber 3a is uniform, and the temperature at different positions has a certain gradient.

[0082] See also Figure 10 The low-temperature annealing system 200 can include multiple annealing units 10a arranged in parallel. Each of the multiple annealing units 10a can be independently controlled, allowing for flexible activation of one or more of them based on actual needs. Simultaneously activating multiple annealing units 10a effectively improves annealing efficiency. Furthermore, the fact that multiple annealing units 10a are arranged in parallel and share a common transmission assembly can shorten production line length and reduce workshop floor space. Furthermore, the multiple annealing units 10a can share the same feed chamber 4 and discharge chamber 8, reducing the structural complexity of the feed chamber 4 and discharge chamber 8, as well as the complexity of the temperature control device 20 and circulation device 70.

[0083] In some embodiments, the low-temperature annealing system 200 may include two annealing units 10a arranged in parallel, each annealing unit 10a corresponds to a loading position 5 and a unloading position 6, and the two annealing units 10a share a feeding chamber 4 and a discharging chamber 8, so that the two annealing units 10a can perform annealing treatment synchronously, thereby improving annealing efficiency.

[0084] See also Figure 10 and Figure 11For the solution of two annealing units 10a arranged in parallel, the two annealing units 10a are in contact with each other without a gap, which facilitates the access and layout of devices such as the temperature control device 20, the vacuum device 30 and the gas source 40, thereby further improving space utilization and rationality of space layout. In some embodiments, Figure 11 As shown, the inner walls of the two process chambers 3 arranged side by side are provided with a first temperature control component 201, and the gas source 40 is introduced into the two chambers through the adjacent side walls of the two process chambers 3, so that the airflow can bring the temperature of the side walls to the middle of the cavity, thereby improving the uniformity of the temperature distribution.

[0085] See also Figure 10 and Figure 12 As shown, for the solution of two annealing units 10a arranged in parallel, a second temperature control component 202 is provided in each of the two discharge cavities 8 arranged in parallel. The structure of the second temperature control component 202 is basically the same as that described above, thereby cooling the battery cells in the two discharge cavities 8. The discharge cavities 8 are connected to a gas source 40, and the gas source 40 is located at the side wall of the two process chambers 3 and introduced into the two discharge cavities 8. In some embodiments, the two discharge cavities 8 can be connected to each other, and the circulation pipeline 703 of the circulation device 70 is connected to the side wall of one discharge cavity 8 at one end and to the side wall of the other discharge cavity 8 at the other end, so that the gas cooling circulation can be performed for the two discharge cavities 8 at the same time.

[0086] In some embodiments, the low-temperature annealing system 200 may include a plurality of annealing units 10 a arranged in parallel, and the plurality of process chambers 3 a included in the plurality of annealing units 10 a share a first vacuum assembly 301 .

[0087] The low temperature annealing system 200 in this embodiment has the following beneficial effects:

[0088] (1) The annealing unit 10a is connected through the vacuum device 30 and the gas source 40. The vacuum device provides a vacuum environment for the annealing unit, and the gas source 40 provides a flowing inert gas for the annealing unit 10a. With the cooperation of the two, the oxidation risk of the metal film during the sintering process can be effectively reduced, the annealing uniformity can be improved, the low-temperature annealing of the metal film can be achieved, and the battery performance can be improved.

[0089] (2) The low-temperature annealing system 100 may include a plurality of annealing units 10a arranged in parallel. The plurality of annealing units 10a can be independently controlled, so that one or more of them can be flexibly selected to be turned on according to actual needs. When the plurality of annealing units 10a are turned on simultaneously, the annealing efficiency can be effectively improved. At the same time, the plurality of annealing units 10a arranged in parallel and sharing a set of transmission components can also shorten the length of the production line and reduce the space occupied by the workshop. In addition, the plurality of annealing units 10a arranged in parallel can share a feed chamber 4 and a discharge chamber 8, which can reduce the structural complexity of the feed chamber 4 and the discharge chamber 8, as well as the setting complexity of the temperature control device 20 and the circulation device 70.

[0090] (3) By providing the circulation device 70, nitrogen can be recycled during the cooling process, thereby reducing nitrogen consumption and further reducing costs.

[0091] (4) In the annealing unit 10a, the feed chamber 4, the process chamber 3a and the discharge chamber 8 are continuously arranged, and the continuous transmission is performed by the transmission component 1a, so that the annealing efficiency can be improved and the structure of the transmission component 1a can be simplified.

[0092] See also Figure 13 , and refer to Figures 1 to 8 The present invention also provides a low-temperature annealing method for solar cells, which is performed using the low-temperature annealing system 100 described above. When the annealing unit 10 includes multiple process chambers 3, and the multiple process chambers 3 share a common inlet and outlet chamber 2, for example, the multiple process chambers 3 may include a first process chamber 3 and a second process chamber 3, respectively. The low-temperature annealing method specifically includes the following steps:

[0093] In step S10 , the battery cell to be processed (eg, the first battery cell) is transferred to the inlet and outlet chamber 2 , and the inlet and outlet chamber 2 is evacuated.

[0094] Specifically, the carrier plate 7 carrying multiple carriers 50 is transferred from the loading position 5 to the outside of the inlet and outlet chamber 2 by the first conveying mechanism 11, and each carrier 50 is stacked with a large number of battery cells. Afterwards, the top isolation door (or hatch) of the inlet and outlet chamber 2 is opened, and the carriers 50 on the carrier plate 7 are transported to the second conveying mechanism 12 in the inlet and outlet chamber 2 by the transfer mechanism 13, wherein the second conveying mechanism 12 can also be provided with the same carrier plate 7 for loading the carriers 50. It can be understood that the transfer mechanism 13 can grab and transfer one carrier 50 at a time, or it can grab and transfer two or more carriers 50 at a time. After all the carriers 50 are transported to the inlet and outlet chamber 2, the inlet and outlet chamber 2 is closed, and the inlet and outlet chamber 2 is evacuated by the second vacuum assembly 302. Before evacuation, nitrogen can also be injected into the inlet and outlet chamber 2 through the gas source 40 to fully replace the air inside, thereby reducing the oxygen content in the chamber.

[0095] In step S20 , the material inlet and outlet chamber 2 is connected to the first process chamber 3 in a vacuum state, and the first battery cell is transferred into the first process chamber 3 .

[0096] Specifically, during the annealing process, since multiple process chambers 3 share one inlet and outlet chamber 2, at this time, an idle first process chamber 3 can be selected, and the first process chamber 3 can be vacuumed in advance through the first vacuum component 301. After the vacuum in the inlet and outlet chamber 2 meets the requirements, the isolation door 9 between the inlet and outlet chamber 2 and the first process chamber 3 can be opened. Under the drive of the second transmission mechanism 12, the carrier plate 7 carrying the carrier rack 50 enters the first process chamber 3 from the inlet and outlet chamber 2, and then the inlet and outlet chamber 2 and the first process chamber 3 are closed.

[0097] Step S30 , heating the first process chamber 3 to perform annealing treatment on the first cell.

[0098] Specifically, the first process chamber 3 can be preheated by the first temperature control component 201, and the first cell can be transferred into the process chamber 3 after reaching a specific temperature. Alternatively, the first cell can be heated after being transferred into the process chamber 3. In this embodiment, the internal space of the first process chamber 3 is limited, and the carrier plate 7 can be stationary after entering the process chamber 3. At this time, the first temperature control component 201 can be used to perform gradient temperature adjustment on the first process chamber 3, so that the first cell is fully preheated in the process chamber 3 and then subjected to a constant temperature annealing treatment for a certain period of time.

[0099] In some embodiments, for the metal film formed by the copper slurry, the gradient temperature control process in the first process chamber 3 mainly includes a heating stage (or preheating stage) and a constant temperature stage. The temperature of the heating stage is 20°C to 400°C, and the time is 3 to 20 minutes; the temperature of the constant temperature stage is 20°C to 400°C, and the time is 3 to 50 minutes. For example, the temperature of the constant temperature stage can be 20°C, 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C or a value between any two of the above values. The heating stage can increase the temperature from room temperature to a certain temperature, and then maintain this temperature in the constant temperature stage. For example, when the constant temperature stage temperature required for annealing is 300°C, the heating stage can increase the temperature from room temperature to 300°C within 3 to 20 minutes, and then the constant temperature stage is maintained at 300°C for 3 to 50 minutes to complete the annealing process. The annealing system 10 of the present application can achieve low-temperature annealing treatment below 400°C.

[0100] In some embodiments, during the annealing process, a flowing inert gas, such as nitrogen, can be introduced into the first process chamber 3 through the gas source 40. An appropriate amount of inert gas can be introduced under a vacuum environment, and it is ensured that the inert gas is always in a flowing state. Driven by the airflow, it is beneficial to uniformly distribute the temperature in the first process chamber 3, improve the uniformity of annealing, and thus improve the annealing effect.

[0101] In some embodiments, while introducing inert gas, a small amount of oxygen can also be introduced into the first process chamber 3. The amount introduced is generally in the range of 0.1ppm to 2000ppm. In the overall inert gas atmosphere, the introduction of a small amount of oxygen will not cause oxidation of the metal film, but can also help improve the annealing effect and reduce the line resistance of the printed grid lines on the surface of the battery cell.

[0102] In step S40 , while the first process chamber 3 is annealing the first cell, the second process chamber 3 is connected to the inlet and outlet chamber 2 , and the annealed second cell is transferred to the inlet and outlet chamber 2 for cooling.

[0103] The annealing process in the second process chamber 3 is substantially the same as that in the first process chamber 3 , and please refer to the aforementioned steps S10 to S30 .

[0104] Specifically, after annealing is complete in the second process chamber 3, the isolation door 9 between the second process chamber 3 and the inlet / outlet chamber 2 is opened, and the second transfer mechanism 12 transfers the annealed second cell into the inlet / outlet chamber 2. At this point, the inlet / outlet chamber 2 is cooled by the second temperature control assembly 202, thereby cooling the second cell. During the cooling process, the cooling rate of the second cell can be controlled by controlling the cooling rate of the second temperature control assembly 202, thereby reducing internal defects in the electrodes formed on the cell and improving battery quality.

[0105] In some embodiments, during the cooling process, flowing inert gas may also be introduced to make the cooling gas in the inlet and outlet cavity 2 more evenly distributed and achieve a better cooling effect on the battery.

[0106] Step S50 , after cooling is completed, inert gas is injected into the inlet and outlet cavity 2 to the atmospheric environment, and the second battery cell after annealing is moved out of the inlet and outlet cavity 2 .

[0107] Specifically, a sufficient amount of nitrogen is injected into the inlet and outlet chamber 2 through the gas source 40 until it reaches the atmospheric environment, and then the top hatch of the inlet and outlet chamber 2 is opened, and the carrier 50 is transferred to the first transmission mechanism 11 through the transfer mechanism 13. The second battery cell after annealing is transferred to the unloading position 6 for temporary storage through the first transmission mechanism 11 for use in the next process, or directly enters the next process from the unloading position 6.

[0108] After the annealing treatment of the first cell in the first process chamber 2 is completed, the first cell may be cooled and discharged according to steps S40 and S50 .

[0109] It can be understood that when the annealing unit 10 includes more than two process chambers 3, it is also possible to flexibly choose to transfer the battery cells in the input and output chamber 2 to the idle process chamber 3 for annealing treatment according to the idle status of each process chamber 3, which can improve the utilization rate of the input and output chamber 2 and each process chamber 3, make full use of the waiting time of the annealing process, and improve the efficiency of the annealing treatment.

[0110] It is also understandable that when the low-temperature annealing system 100 includes two annealing units 10 arranged in parallel, the two annealing units 10 can perform the annealing process simultaneously or independently.

[0111] Conventional annealing processes are mostly high-temperature annealing processes performed at atmospheric pressure, using chain furnaces with long production lines. Driven by the chain, individual carriers are heated in a step-by-step manner, resulting in low annealing efficiency and poor annealing results. Furthermore, these processes are usually open-type, and the metal films used for processing (such as silver paste films) are not easily oxidized in an oxygen environment. Clearly, this type of annealing equipment cannot be used for annealing oxygen-sensitive metal materials.

[0112] The annealing process of the present application is to evacuate both the inlet and outlet chamber 2 and the process chamber 3, and at the same time, a flowing inert gas is injected into the chamber in conjunction with the gas source 40, which can effectively reduce the oxidation of metal materials (such as copper) that are sensitive to oxygen. At the same time, the vacuum environment can greatly reduce the amount of nitrogen used, thereby reducing costs. Moreover, the annealing temperature of the annealing process of the present application can achieve a gradient temperature design, the carrier 50 is stationary in the process chamber 3, the inlet and outlet gases are lateral convection, the thermal field is more uniform, and the metal film can be fully annealed, which is beneficial to reducing the diffusion or penetration of the metal at high temperatures and improving the performance of the battery. The low-temperature annealing process of the present application is simple in process, and the design of the inlet and outlet chamber 2 and multiple process chambers 3 can improve the utilization rate of the inlet and outlet chamber 2 and each process chamber 3, and make full use of the waiting time of the annealing process, effectively improve the annealing efficiency, rationally utilize space, and have low costs, thereby avoiding the conventional lengthy and high-temperature sintering process.

[0113] See also Figure 14 , and refer to Figures 9 to 12 The embodiment of the present application also provides another low-temperature annealing method, which is performed using the above low-temperature annealing system 200.

[0114] In step S10 ′, a plurality of cells to be processed are transferred to the feed chamber 4 , and the feed chamber 4 is evacuated.

[0115] Specifically, the carrier plate 7 carrying multiple carriers 50 is transferred from the loading position 5 to the feed chamber 4 by the transmission component 1a, where a large number of battery cells are stacked on each carrier 50, and then the feed chamber 4 is vacuumed.

[0116] In step S20 ′, the feed chamber 4 is connected to a plurality of process chambers 3 a that are in a vacuum state and arranged side by side, and a plurality of battery cells are transferred into the plurality of process chambers 3 a respectively.

[0117] Specifically, after the feed chamber 4 reaches a preset vacuum environment, the isolation door 9 between the feed chamber 4 and the multiple process chambers 3a arranged side by side is opened. When multiple annealing units 10a share a single feed chamber 4, a single isolation door 9 can be provided between the multiple process chambers 3a arranged side by side and the feed chamber 4, or an isolation door 9 can be provided between each process chamber 3a and the feed chamber 4. After the multiple parallel process chambers 3a are connected to the feed chamber 4, the multiple carriers 7 are driven by the transmission assembly 1a from the feed chamber 4 along the first direction X into each process chamber 3a, and then the isolation door 9 between the feed chamber 4 and the process chamber 3a is closed.

[0118] In step S30 , the plurality of process chambers 3 a are heated, and flowing inert gas is injected into the plurality of process chambers 3 a to perform annealing treatment on the plurality of battery cells.

[0119] Specifically, multiple process chambers 3a are heated by the first temperature control assembly 201. The process chamber 3a includes a first chamber 35 and a second chamber 36 connected in series. The transmission assembly 1a drives the battery cells along the first direction X to enter the first chamber 35 and the second chamber 36 in sequence. The cells are preheated in the first chamber 35 and kept at a constant temperature in the second chamber 36.

[0120] In some embodiments, for the metal film formed by the copper paste, the temperature in the first cavity 35 can be gradiently changed along the first direction X. Specifically, the temperature in the first cavity 35 can be gradiently increased from 20°C to 400°C or any temperature below 400°C along the first direction X to achieve preheating treatment of the battery cell. The temperature in the second cavity 36 can be constant, and the temperature of the part of the first cavity 35 close to the second cavity 36 can be close to 400°C. The specific temperature can be any temperature below 400°C to achieve constant temperature treatment of the battery cell.

[0121] In some embodiments, during the annealing process, an inert gas, such as nitrogen, can be introduced into each process chamber 3a through a gas source 40. The introduction of flowing inert gas under a vacuum environment is conducive to uniform temperature distribution in the process chamber 3a under the drive of the airflow, thereby improving the annealing effect.

[0122] In some embodiments, while introducing inert gas, a small amount of oxygen can also be introduced into the process chamber 3a. The amount introduced is generally in the range of 0.1ppm to 2000ppm. In the overall inert gas atmosphere, the introduction of a small amount of oxygen will not cause oxidation of the metal film, but can also help improve the annealing effect to reduce the line resistance of the printed grid lines on the surface of the battery cell.

[0123] In step S40 ′, the plurality of process chambers 3 a are connected to the discharge chamber 8 in a vacuum state, and the plurality of battery cells after the annealing treatment are transferred to the discharge chamber 8 for cooling treatment.

[0124] Specifically, the discharge chamber 8 is vacuumed in advance. After annealing is completed, the isolation door 9 between the multiple process chambers 3a and the discharge chamber 8 is opened. When multiple annealing units 10a share one discharge chamber 8, an isolation door 9 can be set between the multiple parallel process chambers 3a and the discharge chamber 8, or an isolation door 9 can be set between each process chamber 3a and the discharge chamber 8. When the multiple parallel process chambers 3a are connected to the discharge chamber 8, the transmission component 1a transfers the annealed battery cell to the discharge chamber 8. At this time, the discharge chamber 8 is cooled by the second temperature control component 202, which can cool the battery cell. During the cooling process, the cooling rate of the battery cell can be controlled by controlling the cooling rate of the second temperature control component 202, which is conducive to reducing the internal defects of the electrode formed on the battery cell, thereby improving the quality of the battery.

[0125] In some embodiments, during the cooling process, flowing inert gas (such as nitrogen) may also be introduced to make the cooling gas in the discharge cavity 8 more evenly distributed and improve the cooling effect of the battery.

[0126] In step S50 ′, after cooling, an inert gas is injected into the discharge chamber 8 through the gas source 40 to the atmospheric environment, and the annealed cell is removed from the discharge chamber 8 .

[0127] Specifically, a sufficient amount of nitrogen is injected into the discharge chamber 8 through the gas source 40 until it reaches the atmospheric environment, and then the isolation door 9 of the discharge chamber 8 is opened, and the annealed battery cells are transferred to the discharge position 6 for temporary storage through the transmission component 1a for use in the next process, or directly enter the next process from the discharge position 6.

[0128] It is understandable that when the low-temperature annealing system 200 includes two annealing units 10 a arranged in parallel, the two annealing units 10 a can perform annealing treatment simultaneously or independently.

[0129] Compared with the above embodiment, the present embodiment can realize continuous annealing through the above low temperature annealing system 200, further improving the annealing efficiency. In addition, the annealing method of the present embodiment can also design multiple process chambers 3a in series according to the process cycle requirements.

[0130] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application should not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A low temperature annealing system, characterized in that: The low temperature annealing system comprises: Multiple annealing units are arranged in parallel, each comprising a feed chamber, a process chamber, and a discharge chamber. Each of the feed chamber, the process chamber, and the discharge chamber can be interconnected or isolated from each other, and each of the feed chamber and the discharge chamber can be connected to or isolated from the outside. The annealing unit is used to anneal a cell provided with a base metal slurry to form an electrode. A transport assembly, configured to move the cell into or out of the plurality of annealing units, and to transport the cell between the feed chamber, the process chamber, and the discharge chamber; a temperature control device, comprising a first temperature control component located in the process chamber and a second temperature control component located in the discharge chamber, wherein the first temperature control component is used to heat the process chamber and the second temperature control component is used to cool the discharge chamber; a vacuum device, connected to the annealing unit, and configured to provide a vacuum environment for the annealing unit; A gas source is connected to the annealing unit, and is used to provide flowing inert gas to the annealing unit.

2. The low temperature annealing system according to claim 1, characterized in that: The feed chamber and the discharge chamber are the same chamber, the annealing unit includes a plurality of process chambers, and the feed chamber is located between the plurality of process chambers.

3. The low temperature annealing system according to claim 2, characterized in that: The transmission component includes: A first transport mechanism is located outside the annealing unit, and is used to move the cell to or from the outside of the feed chamber; A second transport mechanism is located inside the annealing unit, and is used to drive the cell to transfer between the feed chamber and each of the process chambers; A transfer mechanism is located above the feed cavity and the first transmission mechanism, and is used to transfer the battery cells between the first transmission mechanism and the second transmission mechanism.

4. The low temperature annealing system according to claim 3, characterized in that: It comprises a plurality of annealing units arranged in parallel, and a first transmission mechanism and a transfer mechanism are provided between two adjacent annealing units.

5. The low temperature annealing system according to claim 1, characterized in that: It includes multiple annealing units arranged side by side, and the multiple annealing units share the same feed chamber and the discharge chamber. The feed chamber and the discharge chamber are respectively located at opposite ends of the process chamber. Along the first direction from the feed chamber to the discharge chamber, the process chamber includes multiple chambers connected in series.

6. The low temperature annealing system according to any one of claims 1 to 5, characterized in that: The vacuum device includes a first vacuum component and a second vacuum component. The first vacuum component is connected to the process chamber to provide a vacuum environment for the process chamber; the second vacuum component is connected to the feed chamber and the discharge chamber respectively to provide a vacuum environment for the feed chamber and the discharge chamber.

7. The low temperature annealing system according to any one of claims 1 to 6, characterized in that: The process chamber includes a preheating zone and a constant temperature zone that are interconnected. The temperature gradient of the preheating zone increases along the direction from the preheating zone to the constant temperature zone.

8. The low temperature annealing system according to any one of claims 1 to 7, characterized in that: It also includes a circulation device communicated with the discharge cavity, and the circulation device is used to cool the inert gas discharged from the discharge cavity and recycle it.

9. The low temperature annealing system according to any one of claims 1 to 8, characterized in that: Along the transmission direction perpendicular to the battery slices, each process chamber has a plurality of processing areas arranged in parallel, and a flow equalizing plate is provided between two adjacent processing areas.

10. The low temperature annealing system according to any one of claims 1 to 9, characterized in that: The second temperature control component includes cooling coils distributed around the discharge cavity, and coolant is provided in the cooling coils.

11. A low temperature annealing method, characterized in that: include: Transferring the first battery cell to be processed to the inlet and outlet chamber, and evacuating the inlet and outlet chamber; Connecting the inlet and outlet chamber to the first process chamber in a vacuum state, and transferring the first battery cell into the first process chamber; heating the first process chamber and injecting flowing inert gas into the first process chamber to perform annealing on the first cell; During the process of annealing the first cell in the first process chamber, connecting the second process chamber and the inlet and outlet chamber, and transferring the second cell after annealing in the second process chamber to the inlet and outlet chamber for cooling; After cooling, inert gas is injected into the inlet and outlet cavity to the atmospheric environment, and the second battery cell after annealing is moved out of the inlet and outlet cavity.

12. The low temperature annealing method according to claim 11, characterized in that: During the annealing process of the battery cell, the battery cell is stationary in the process chamber. The annealing process includes a gradient temperature control process, which includes a temperature rising stage and a constant temperature stage.

13. The low temperature annealing method according to claim 11 or 12, characterized in that: During the cooling process, the method further comprises: The inert gas in the inlet and outlet cavity is cooled and recycled.

14. A low temperature annealing method, characterized in that: include: Transferring a plurality of battery cells to be processed to a feed chamber, and evacuating the feed chamber; Connecting the feed chamber to a plurality of process chambers in a vacuum state and arranged side by side, and transferring the plurality of battery cells into the plurality of process chambers respectively; heating the plurality of process chambers and injecting flowing inert gas into the plurality of process chambers to perform annealing treatment on the plurality of battery cells respectively; Connecting the multiple process chambers to a discharge chamber in a vacuum state, and transferring the multiple battery cells after annealing to the discharge chamber for cooling. During the cooling process, flowing inert gas is injected into the discharge chamber; After cooling, inert gas is injected into the discharge cavity to the atmospheric environment, and the battery cell after annealing is moved out of the discharge cavity.

15. The low temperature annealing method according to claim 14, characterized in that: During the cooling process, the method further comprises: The inert gas in the discharge cavity is cooled and recycled.

16. The low temperature annealing method according to claim 14 or 15, characterized in that: Along a first direction from the feed chamber to the discharge chamber, the process chamber includes a first chamber and a second chamber connected in series, and in the step of annealing the battery cell, the method includes: The battery cell is driven to enter the first cavity and the second cavity in sequence for annealing treatment, wherein along the first direction, the temperature gradient in the first cavity increases, and the temperature in the second cavity remains constant.

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