A pole piece pre-lithiation device and pole piece pre-lithiation method

Abstract

The present application discloses a pole piece pre-lithiation device and a pole piece pre-lithiation method. The pole piece pre-lithiation device includes a pre-lithiation unit, which includes a pre-lithiation platform and a pre-lithiation cavity; the pre-lithiation platform is used to carry the pole piece strip, and the pole piece strip is coated with an active material coating at intervals; the pre-lithiation cavity is set corresponding to the pre-lithiation platform, and the pre-lithiation cavity includes a pre-lithiation box, a heating structure and an electrolyte layer provided at the front end of the pre-lithiation box, the heating structure is used to heat the molten salt and lithium source inside the pre-lithiation box into a molten state, and the pre-lithiation surface of the electrolyte layer is used to contact the active material coating on the pre-lithiation platform, so that when the pre-lithiation voltage is loaded on the pre-lithiation cavity, the Li in the pre-lithiation cavity is heated. + The active material coating is embedded through the electrolyte layer. The electrochemical pre-lithiation method is used to transfer Li through surface-to-surface contact. + , directly Li + Replenishing into the active material coating makes it easier to control the lithium replenishment area and prevent Li + Overflow to the gap between two adjacent active material coatings.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole piece pre-lithiation device and a pole piece pre-lithiation method. Background Art

[0002] In recent years, industry experts have been exploring methods for pre-lithiation of negative electrode sheets to address the low coulombic efficiency of lithium batteries during the initial charge and discharge process, while also improving battery energy density and cycle life. Related pre-lithiation methods include lithium powder, spraying, impregnation, and rolling.

[0003] There are continuous coating and intermittent coating processes in the production of active material coating on the electrode. There is a spacing area (blank area) between the intermittent coating layers. The pre-lithiation method in the related art is difficult to avoid the spacing area during the continuous pre-lithiation operation, resulting in lithium generation or residual lithium in the spacing area. Summary of the Invention

[0004] The embodiments of the present application provide a pole piece pre-lithiation device and a pole piece pre-lithiation method, which can solve the problem that it is difficult to avoid the spacing area of the active material coating of the pole piece in the pre-lithiation method.

[0005] In a first aspect, an embodiment of the present application provides a pole piece pre-lithiation device, comprising a pre-lithiation unit, wherein the pre-lithiation unit comprises a pre-lithiation platform and a pre-lithiation cavity;

[0006] The pre-lithium platform is used to carry the pole piece strips, and the pole piece strips are coated with active material coatings at intervals;

[0007] The pre-lithium cavity is arranged corresponding to the pre-lithium platform, and the pre-lithium cavity includes a pre-lithium box, a heating structure and an electrolyte layer arranged at the front end of the pre-lithium box. The interior of the pre-lithium box has a storage space for molten salt and lithium source. The heating structure is used to heat the molten salt and lithium source into a molten state. The surface of the electrolyte layer is a pre-lithium surface, which is used to contact the active material coating on the pre-lithium platform so that the Li in the pre-lithium cavity is heated when the pre-lithium voltage is loaded. + The active material coating is embedded through the electrolyte layer.

[0008] In some embodiments, the pre-lithium platform includes a heating component, and the heating component is used to heat the active material coating on the pre-lithium platform; and / or,

[0009] The heating structure in the pre-lithium cavity includes a heating layer arranged outside the pre-lithium box, and the heating layer is used to heat the molten salt and lithium source inside the pre-lithium box.

[0010] In some embodiments, the pre-lithium box includes a main box and a sub-box connected to the main box, the molten salt and lithium source are injected into the main box through the sub-box, and the electrolyte layer is provided at the front end of the main box.

[0011] In some embodiments, the sub-box is located above the main box, the sub-box is connected to the main box through a linear pipe, and the molten salt and lithium source in the main box are above the electrolyte layer; or

[0012] The sub-box is located on the side of the main box, and the sub-box is connected to the main box through a zigzag pipe. The molten salt and lithium source in the main box are below the electrolyte layer, and the liquid level of the molten salt and lithium source in the sub-box is higher than the liquid level of the molten salt and lithium source in the main box.

[0013] In some embodiments, the pre-lithium chamber further includes a gas release valve;

[0014] The air release valve is installed on the main box body, and the air release valve is communicated with the main storage space formed by the main box body to discharge the gas in the main storage space; or,

[0015] The air release valve is installed on the sub-box body, and the air release valve is communicated with the sub-accommodation space enclosed by the sub-box body to discharge gas in the sub-accommodation space.

[0016] In some embodiments, there are a plurality of pre-lithiation units, and the plurality of pre-lithiation units are arranged at intervals along a preset conveying direction.

[0017] In some embodiments, the plurality of pre-lithium units include a plurality of pre-lithium platforms and a plurality of pre-lithium cavities;

[0018] Wherein, the plurality of pre-lithium platforms are sequentially spaced apart along the preset conveying direction;

[0019] Along a direction perpendicular to the preset conveying direction, a plurality of the pre-lithiation cavities are arranged on the same side of the pre-lithiation platform; or,

[0020] Along a direction perpendicular to the preset conveying direction, a portion of the pre-lithium cavities are arranged on the same side of the pre-lithium platform, and another portion of the pre-lithium cavities are arranged on the other side of the pre-lithium platform.

[0021] In some embodiments, when a portion of the pre-lithium cavities are located on one side of the pre-lithium platform and another portion of the pre-lithium cavities are located on the other side of the pre-lithium platform, two adjacent pre-lithium cavities are located on different sides of the pre-lithium platform.

[0022] In some embodiments, the preset transport direction is a horizontal direction, and the pre-lithiation surface of the electrolyte layer is a plane parallel to the horizontal direction.

[0023] In some embodiments, the electrode pre-lithiation equipment further includes a preheating unit and a strip retracting mechanism;

[0024] The preheating unit includes a preheating platform for carrying the pole piece strip;

[0025] The strip retracting mechanism is used to sequentially transport the active material coating on the electrode strip along a preset transport direction to the preheating platform and the pre-lithium platform;

[0026] Wherein, the preheating platform is used to heat the active material coating on the preheating platform.

[0027] In some embodiments, the electrolyte layer comprises a solid electrolyte.

[0028] In some embodiments, the pre-lithium chamber further includes a sacrificial electrode configured to contact the molten salt and the lithium source.

[0029] In a second aspect, an embodiment of the present application provides a pole piece pre-lithiation method corresponding to the pole piece pre-lithiation device as described above, comprising:

[0030] Providing a pole piece strip, wherein the pole piece strip is coated with an active material coating at intervals;

[0031] Adding molten salt and lithium source into the pre-lithium box, and heating the molten salt and lithium source to make them molten;

[0032] The pre-lithium surface of the electrolyte layer is brought into contact with the active material coating on the pre-lithium platform, and a pre-lithium voltage is applied to perform a pre-lithium treatment so that the Li + The active material coating of the electrode strip is embedded through the electrolyte layer.

[0033] In some embodiments, applying a pre-lithium voltage comprises:

[0034] A pre-lithium circuit is provided, the positive electrode of the pre-lithium circuit is electrically connected to the pre-lithium cavity, the negative electrode is electrically connected to the current collector of the electrode strip, and the pre-lithium surface of the electrolyte layer is in contact with the active material coating to apply a pre-lithium voltage.

[0035] In some embodiments, the pre-lithium treatment conditions include: the current density applied to the pre-lithium chamber by the pre-lithium circuit is β, the pre-lithium voltage is M, and the pre-lithium temperature is T x , meeting at least one of the following conditions:

[0036] (1) 20mA / cm 2 ≤β≤56mA / cm 2 ;

[0037] (2) 2.6V≤M≤4.5V;

[0038] (3)110℃≤T x ≤130℃;

[0039] Preferably,

[0040] (1)35mA / cm 2 ≤β≤45mA / cm 2 ;

[0041] (2) 3.3V≤M≤3.8V;

[0042] (3)110℃≤T x ≤120℃;

[0043] Wherein, the pre-lithium temperature is T x is the temperature of the pre-lithium platform.

[0044] In some embodiments, heating the molten salt and the lithium source to form a molten state comprises:

[0045] The heating layer of the pre-lithium cavity heats the molten salt and lithium source inside the pre-lithium cavity to a melting temperature T y , so that the molten salt and lithium source are in a molten state, 110℃≤T y ≤120℃.

[0046] In some embodiments, during the pre-lithiation process, the pressure applied by the electrolyte layer to the surface to be pre-lithiation is P, 0.1 Kg / cm 2 T≤P≤20Kg / cm 2 .

[0047] In some embodiments, before performing the pre-lithium treatment, the method further includes:

[0048] The active material coating of the electrode strip is transported to the preheating platform of the preheating unit by using the strip retracting mechanism, and after preheating, it is transported to the pre-lithium unit along a preset transport direction.

[0049] In some embodiments, the temperature Tc of the preheating treatment is: 105°C ≤ Tc ≤ 125°C.

[0050] In some embodiments, the active material coatings applied alternately on the electrode strip are transported to the pre-lithiation platform for single-sided pre-lithiation, wherein the pre-lithiation cavity is provided on the same side of the pre-lithiation platform;

[0051] There is at least one pre-lithium platform;

[0052] There is at least one pre-lithium cavity.

[0053] In some embodiments, the active material coatings applied at intervals on the electrode strip are transported to a plurality of the pre-lithiation platforms for double-sided pre-lithiation, wherein a portion of the pre-lithiation cavity is provided on one side of the plurality of the pre-lithiation platforms and a portion of the pre-lithiation cavity is also provided on the other side.

[0054] In this application, "a plurality of" means at least two.

[0055] Based on the electrode pre-lithiation device and electrode pre-lithiation method of the embodiment of the present application, an electrochemical pre-lithiation method is adopted, and the surface of the electrolyte layer of the electrode pre-lithiation device is set to contact the surface of the active material coating, and the Li is transferred by surface-to-surface contact. + , directly Li + Replenishing into the active material coating makes it easier to control the lithium replenishment area and prevent Li + Overflowing to the gap between two adjacent active material coatings makes lithiation more uniform and easier to control. When the negative electrode is used in a battery, it can improve the problem of low initial coulombic efficiency of the negative electrode, thereby effectively improving the energy density and cycle life of the lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0057] Figure 1 This is a schematic structural diagram of a pole piece pre-lithiation device according to an embodiment of the present application;

[0058] Figure 2 This is a schematic diagram of the main structure of a pole piece strip according to an embodiment of the present application;

[0059] Figure 3 This is a structural diagram of an embodiment of the present application in which a sub-box is connected to the top wall of the main box;

[0060] Figure 4 This is a structural diagram of an embodiment of the present application in which the sub-box is connected to the side wall of the main box.

[0061] Figure 5 This is a structural schematic diagram of a pole piece pre-lithiation device according to another embodiment of the present application;

[0062] Figure 6This is a schematic side view of the structure of a pole piece strip according to an embodiment of the present application.

[0063] Reference numerals:

[0064] 10. Electrode pre-lithiation equipment;

[0065] 100, pre-lithium unit; 101, first pre-lithium unit; 102, second pre-lithium unit; 110, pre-lithium platform; 120, pre-lithium chamber; 121, electrolyte layer; 123, pre-lithium box; 1231, main box; 1232, sub-box; 125, air release valve; 126, liquid level detector; 130, drive assembly;

[0066] 200, preheating unit; 210, preheating platform;

[0067] 310, unwinding assembly; 3101, unwinding roller; 311, unwinding roller; 312, unwinding splicing platform; 313, unwinding pressure bar; 314, unwinding correction system; 315, unwinding tension detection system; 320, rewinding assembly; 321, rewinding roller; 322, rewinding splicing platform; 323, rewinding pressure bar; 324, rewinding correction system; 325, rewinding tension detection system;

[0068] 500, positioning sensing device; X, preset conveying direction;

[0069] 20. Pole strip; 21. Current collector substrate; 22. Active material coating; 221. Spacer area. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0071] In the related art, lithium ions are added to the active material coating of the negative electrode of the battery through pre-lithiation treatment, which can improve the low coulombic efficiency of the battery during the first charge and discharge process, and at the same time improve the battery energy density and charge and discharge cycle life. There are two methods for coating the active material coating on the electrode in the production process: continuous coating and intermittent coating. The intermittent coating method is to coat multiple layers of active material coating on the surface of the current collector substrate of the electrode at intervals, leaving a spacing area (blank area) between two adjacent active material coatings. In the subsequent process, the tabs can be welded to the spacing area. The pre-lithiation methods in the related art, such as lithium powder method, spraying method, infiltration method, calendering method, etc., are difficult to avoid the spacing area during the continuous pre-lithiation operation, resulting in lithium generation or residual lithium in the spacing area, which directly affects the subsequent tab welding, resulting in problems such as cold welding, low welding strength, or even inability to weld. At the same time, there are also common problems such as uneven lithiation, difficulty in controlling the degree of lithiation, residual lithium replenishment solvent affecting electrical performance, and limited electrode width. Based on this, the present application provides a pole piece pre-lithiation device and a pole piece pre-lithiation method to optimize the pole piece pre-lithiation effect.

[0072] like Figure 1 , which is a structural diagram of a pole piece pre-lithiation device 10 according to an embodiment of the present application. The pole piece pre-lithiation device 10 includes a pre-lithiation unit 100 , and the pre-lithiation unit 100 includes a pre-lithiation platform 110 and a pre-lithiation cavity 120 .

[0073] Among them, the pre-lithium platform 110 is used to carry the pole piece strip 20, such as Figure 2 As shown, active material coatings 22 are applied at intervals on the electrode strip 20, and there is a spacing area 221 between two adjacent active material coatings 22 of the electrode strip 20. The electrode strip 20 can be cut at the spacing area 221 to cut the electrode strip 20 into multiple electrode sheets, which can be used as negative electrode sheets in batteries.

[0074] See also Figure 1 The pre-lithium cavity 120 is provided corresponding to the pre-lithium platform 110. The pre-lithium cavity 120 includes a pre-lithium box 123 and an electrolyte layer 121 provided at the front end of the pre-lithium box 123. The pre-lithium box 123 has a storage space for accommodating molten salt and lithium source R. The surface of the electrolyte layer 121 is a pre-lithium surface, which is used to contact the active material coating 22 on the pre-lithium platform 110 so that when the pre-lithium cavity 120 is loaded with a pre-lithium voltage, the Li in the pre-lithium box 123 is heated to 100 ℃. + The active material coating layer 22 is embedded through the electrolyte layer 121 .

[0075] The electrode pre-lithiation device 10 of the embodiment of the present application sets the surface of the electrolyte layer 121 in contact with the surface of the active material coating 22, and transfers Li in a surface-to-surface contact manner. + , directly Li +Replenishing into the active material coating 22 facilitates the control of lithium replenishment area and prevents Li + Overflowing to the spacing area 221 between two adjacent active material coatings 22 makes lithiation more uniform and easier to control, and thus when the negative electrode sheet is used in a battery, it can improve the problem of low initial coulombic efficiency of the negative electrode sheet, thereby effectively improving the energy density and cycle life of the battery.

[0076] The active material coating 22 includes a surface to be pre-lithiumed for contacting the pre-lithium surface. The size of the pre-lithium surface of the electrolyte layer 121 can be designed to be larger. When the pre-lithium surface of the electrolyte layer 121 contacts the surface to be pre-lithiumed of the active material coating 22, the pre-lithium surface of the electrolyte layer can completely cover the surface to be pre-lithiumed of the active material coating, solving the problem of limited width of the active material coating 22 in the calendering method, for example. The active material coating 22 of conventional (≤500mm*500mm) negative electrode sheets on the market can be pre-lithiumed, solving the problem of limited width (<300mm) of the active material coating 22 and low production efficiency in the traditional pre-lithium calendering method.

[0077] The electrode pre-lithiation device 10 of the embodiment of the present application adopts an electrochemical pre-lithiation method. + When the lithium is replenished through the solid electrolyte and reaches the active material coating 22 for pre-lithiation, there is no liquid phase. Therefore, compared with the solution method for lithium replenishment, the problem of residual lithium replenishment solvent affecting the electrical performance of the battery is solved. In addition, the lithium replenishment method in the related art also includes spraying method and immersion method. The spraying method and immersion method both involve lithium replenishment solvents. The lithium replenishment solvents are generally volatile or toxic organic solvents, and a solvent recovery system needs to be installed. The lithium replenishment method in the embodiment of the present application does not require additional investment in solvent recovery equipment, saving the cost of lithium replenishment. The lithium replenishment method in the related art also includes the lithium powder method. The lithium powder method is prone to lithium powder and other raw materials densely distributed in the air. Lithium powder is active and flammable, and there are safety hazards. In the lithium replenishment method in the embodiment of the present application, each raw material is bound in a physical structure and has good safety.

[0078] like Figure 1As shown, the electrode pre-lithiation equipment 10 also includes a preheating unit 200 and a strip retracting mechanism. The preheating unit 200 includes a preheating platform 210 for carrying the electrode strip 20. The preheating platform 210 and the pre-lithiation platform 110 are arranged at intervals along the preset conveying direction X. The strip retracting mechanism is used to convey the active material coating 22 of the electrode strip 20 to the preheating platform 210 and the pre-lithiation platform 110 in sequence along the preset conveying direction X. The preheating platform 210 and the pre-lithiation platform 110 jointly provide support for the electrode strip 20 and are used to adjust the position of the electrode strip 20 so that the electrode strip 20 can be conveyed along the preset conveying direction X. Optionally, the preset conveying direction X is a horizontal direction, and the pre-lithiation surface of the electrolyte layer 121 is a plane parallel to the horizontal direction. Correspondingly, the surface to be pre-lithiated of the active material coating 22 is parallel to the pre-lithiated surface of the electrolyte layer, and the surface to be pre-lithiated is also a plane parallel to the horizontal direction. In some other embodiments, the preset conveying direction X may also be a direction at an angle to the horizontal direction.

[0079] Li in the embodiment of this application + In a hot environment, the active material coating 22 can be embedded more smoothly through the electrolyte layer 121. The preheating platform 210 is also used to heat the active material coating 22 on the preheating platform 210. After the preheating platform 210 heats the active material coating 22, the strip retracting mechanism transports the heated active material coating 22 along the preset transport direction X to the pre-lithium platform 110, so that the active material coating 22 still has a high temperature after arriving at the pre-lithium platform 110, so that Li + The active material coating 22 is embedded more efficiently.

[0080] In some embodiments, the pre-lithium platform 110 includes a heating component for heating the active material coating 22 on the pre-lithium platform 110 to further heat or keep the active material coating 22 warm, so that the active material coating 22 is always at a higher temperature, which is convenient for Li + It is understandable that when pre-lithiation is performed on each layer of active material coating 22, a period of pre-lithiation is required to meet the lithium insertion amount of the active material coating 22 of the layer. While pre-lithiation is performed on one layer of active material coating 22, the pre-lithiation platform 110 can preheat the next active material coating 22 at the front end, and the next active material coating 22 can be preheated at the same time during the pre-lithiation period, thereby effectively improving work efficiency.

[0081] In some embodiments, the pre-lithium cavity 120 further includes a heating structure for heating the molten salt and the lithium source into a molten state. Optionally, a heating layer is provided on the outside of the pre-lithium box 123, the heating layer generates heat, and the heat is transferred to the molten salt and the lithium source R inside the pre-lithium box 123 to heat the molten salt and the lithium source R inside the pre-lithium box 123, and heat the molten salt and the lithium source R to a molten state. In this way, when the pre-lithium voltage is loaded on the pre-lithium cavity 120, the Li in the pre-lithium cavity 120 is heated. + The active material coating 22 is embedded through the electrolyte layer 121. The heating layer maintains the molten salt and the lithium source R at a higher temperature, so that the molten salt and the lithium source R can maintain a molten state, and prevent the molten salt and the lithium source R from being locally crystallized and affecting the Li + The uniform stability of the electrolyte layer 121 is improved to improve the pre-lithiation effect. In some other embodiments, a heating structure including an electric heater may also be provided. The electric heater is installed in the pre-lithiation box 123 and extends into the molten salt and lithium source R in the pre-lithiation box 123 to heat the molten salt and lithium source R to a molten state.

[0082] like Figure 3 and Figure 4 As shown, in some embodiments, the pre-lithium box 123 includes a main box 1231 and a sub-box 1232 connected to the main box 1231. The volume of the main box 1231 is larger than the volume of the sub-box 1232. The interior of the main box 1231 is used to accommodate a large amount of molten salt and lithium source R, and the interior of the sub-box 1232 can be used to accommodate a small amount of molten salt and lithium source R. The electrolyte layer 121 is arranged at the front end of the main box 1231. When the molten salt and lithium source R inside the main box 1231 are consumed, the molten salt and lithium source R in the sub-box 1232 can be supplied to the main box 1231 to replenish the consumed molten salt and lithium source R in the main box 1231 in time. Among them, molten salt and lithium source R can be injected into the main box 1231 through the sub-box 1232, guiding the molten salt and lithium source R to enter the main box 1231 more smoothly, reducing the amount of bubbles in the molten salt and lithium source R mixed into the main box 1231.

[0083] When the pre-lithiation cavity 120 includes a heating layer, the heating layer may be provided on the outside of the main box 1231 to heat the molten salt and lithium source R in the main box 1231, or the number of heating layers may be multiple, wherein a portion of the heating layer is provided on the outside of the main box 1231 to heat the molten salt and lithium source R in the main box 1231, and another portion of the heating layer is provided on the outside of the sub-box 1232 to heat the molten salt and lithium source R in the sub-box 1232. When pre-lithiation is performed on the active material layer on the pre-lithiation platform 110, gas should be prevented from mixing into the molten molten salt and lithium source R to ensure that the Li2O3 entering the electrolyte layer 121 is not heated. + Uniformity of distribution.

[0084] In some embodiments, as Figure 3and Figure 4 As shown, the liquid level of the molten salt and lithium source R in the sub-box 1232 is higher than the liquid level of the molten salt and lithium source R in the main box 1231. The liquid level difference is used to timely replenish the molten salt and lithium source R in the sub-box 1232 to the main box 1231, so that the main box 1231 contains an appropriate amount of molten salt and lithium source R, preventing unnecessary gas from mixing into the molten molten salt and lithium source R in the main box 1231.

[0085] In some embodiments, the pre-lithium chamber 120 further includes a gas release valve 125. Optionally, the gas release valve 125 is mounted on the main housing 1231 and communicates with the main accommodation space enclosed by the main housing 1231 to discharge gas from the main accommodation space. This also facilitates smooth entry of the molten salt and the lithium source R into the main housing 1231, allowing gas to be discharged in a timely manner, reducing the probability of gas mixing with the molten salt and lithium source R, and allowing the molten salt and lithium source R to more fully cover the electrolyte layer 121. Optionally, the gas release valve 125 is mounted on the sub-housing 1232 and communicates with the sub-housing space enclosed by the sub-housing 1232 to discharge gas from the sub-housing space, reducing the probability of gas mixing with the molten salt and lithium source R in the sub-housing 1232, thereby reducing the probability of gas being brought into the main housing 1231.

[0086] In some embodiments, the pre-lithium cavity 120 also includes a liquid level detector 126, which is arranged above the electrolyte layer 121 along the direction of gravity. The liquid level detector 126 is used to obtain the liquid level of the molten salt and lithium source R in the pre-lithium cavity 120, and generate a liquid level signal. According to the liquid level signal, the molten salt and lithium source R are replenished into the main box 1231 to prevent the amount of molten salt and lithium source R in the main box 1231 from being too small, resulting in the molten salt and lithium source R failing to completely cover the electrolyte layer 121.

[0087] Alternatively, as Figure 3 As shown, when the molten salt and lithium source R in the main tank 1231 are located above the electrolyte layer 121 in the direction of gravity, the molten molten salt and lithium source R rely on gravity to settle and cover the electrolyte layer 121. At this time, a liquid level detector 126 is provided and installed on the main tank 1231 to directly detect the liquid level of the molten salt and lithium source R in the main tank 1231. Based on the liquid level signal generated when the liquid level detector 126 detects that the liquid level of the molten salt and lithium source R in the main tank 1231 is lower than the position of the liquid level detector 126, the molten salt and lithium source R can be replenished into the main tank 1231 so that the molten salt and lithium source R can more fully cover the electrolyte layer 121.

[0088] In this device, for Figure 3The sub-box 1232 is shown located above the main box 1231. When adding materials (molten salt and lithium source R), the liquid enters the main box 1231 from the sub-box 1232 to ensure smooth addition of the liquid. The sub-box 1232 acts as a buffer to prevent the introduction of excessive bubbles that would affect the pre-lithiation effect. At this time, the sub-box 1232 and the main box 1231 can be connected via a linear pipe. The molten salt and lithium source R in the main box 1231 are above the electrolyte layer 121. The linear pipe can be a linear pipe that is angled with the horizontal direction.

[0089] Alternatively, as Figure 4 As shown, when the molten salt and lithium source R in the main tank 1231 are located below the electrolyte layer 121 in the direction of gravity, due to the liquid level difference, the molten salt and lithium source R in the main tank 1231 rely on the molten salt and lithium source R in the sub-tank 1232 to squeeze and cover the electrolyte layer 121. At this time, a liquid level detector 126 is provided and installed in the sub-tank 1232 to detect the liquid level of the molten salt and lithium source R in the sub-tank 1232. Based on the liquid level signal generated when the liquid level detector 126 detects that the liquid level of the molten salt and lithium source R in the sub-tank 1232 is lower than the position of the liquid level detector 126, the molten salt and lithium source R can be replenished into the sub-tank 1232, and the molten salt and lithium source R in the main tank 1231 can be replenished based on the liquid level difference, so that the molten salt and lithium source R can more fully cover the electrolyte layer 121.

[0090] In this device, for Figure 4 In the structure shown, the liquid level of the sub-box 1232 needs to be higher than the liquid level in the main box 1231 to ensure that the main box 1231 is always in a fully filled state, to prevent gas from entering the main box 1231, affecting the contact between the molten salt and the lithium source R and the solid electrolyte layer 121, and thus affecting the pre-lithium. At this time, the sub-box 1232 can be located on the side of the main box 1231, and the sub-box 1232 and the main box 1231 are connected through a zigzag pipe or a straight pipe. For example, the zigzag pipe can be an L-shaped pipe or a U-shaped pipe, and the straight pipe connection can be a straight pipe that is angled with both the horizontal and vertical directions. The molten salt and lithium source R in the main box 1231 are below the electrolyte layer 121, and the liquid level of the molten salt and lithium source R in the sub-box 1232 is higher than the liquid level of the molten salt and lithium source R in the main box 1231.

[0091] The electrode strip 20 includes a current collector substrate 21 and multiple active material coatings 22 arranged on the surface of the current collector substrate 21. Multiple active material coatings 22 can be arranged on the same surface of the current collector substrate 21, or a part of the active material coatings 22 can be arranged on one surface of the current collector substrate 21 and the remaining active material coatings 22 can be arranged on the other surface of the current collector substrate 21.

[0092] In some embodiments, the electrode pre-lithiation equipment 10 may include a group of pre-lithiation units 100 and a preheating platform 210 , and a pre-lithiation unit 100 sequentially performs pre-lithiation treatment on multiple active material coatings 22 of the electrode strip 20 .

[0093] In some embodiments, the electrode pre-lithiation equipment 10 may include multiple groups of pre-lithiation units 100, which are arranged at intervals along a preset conveying direction X. The active material coating 22 of the electrode strip 20 is pre-lithiated by the multiple groups of pre-lithiation units 100 to improve the pre-lithiation efficiency.

[0094] Optionally, see Figure 1 The electrode pre-lithiation equipment 10 may include multiple groups of pre-lithiation units 100 and a group of preheating platforms 210. After being preheated by the preheating platforms 210, each active material coating 22 of the electrode strip 20 passes through multiple pre-lithiation units 100 in sequence. Each time, the active material coating 22 contacts the pre-lithiation surface of the electrolyte layer 121 of at least one pre-lithiation unit 100 for at least one pre-lithiation treatment, thus completing the pre-lithiation treatment of the active material coating 22. In addition, along the preset conveying direction X, the spacing between the preheating platform 210 and the pre-lithiation platform 110, as well as the spacing between two adjacent pre-lithiation platforms 110, are equal.

[0095] In some embodiments, as Figure 5 As shown, the electrode pre-lithiation equipment 10 may include multiple groups of pre-lithium units 100 and multiple preheating platforms 210, which can divide the multiple active material coatings 22 of the electrode strip 20 into one group, move the multiple active material coatings 22 of the same group to a one-to-one correspondence with the multiple preheating platforms 210 and preheat, and then move along the preset conveying direction X to a one-to-one correspondence with the multiple pre-lithium units 100. After the electrolyte layers 121 of the multiple pre-lithium units 100 are pre-lithium treated in a one-to-one correspondence with the multiple active material coatings 22 of the same group, the pre-lithium treatment of the multiple active material coatings 22 of the group is completed. While the pre-lithium treatment of the multiple active material coatings 22 of the group is being carried out, the multiple active material coatings 22 of the next group are moved to a one-to-one correspondence with the multiple preheating platforms 210 for preheating, and the multiple groups of active material coatings 22 are moved in sequence for preheating and pre-lithium treatment. Among them, the spacing between two adjacent preheating platforms 210 and the spacing between two adjacent pre-lithium platforms 110 can be selected according to the spacing between two adjacent active material coatings 22.

[0096] When there are multiple pre-lithium units 100, the multiple pre-lithium units 100 include multiple pre-lithium platforms 110 and multiple pre-lithium cavities 120, wherein the multiple pre-lithium platforms 110 are arranged in sequence along the preset conveying direction X, that is, the pre-lithium unit 100 has a carrying surface for carrying the electrode strip 20, and the carrying surfaces of the multiple pre-lithium platforms 110 are distributed on the same straight line and in the same plane, so that the electrode strip 20 can be transported in a straight direction to prevent the position of the electrode strip 20 from being offset.

[0097] In some embodiments, a plurality of pre-lithiation cavities 120 are provided on the same side of a plurality of pre-lithiation platforms 110 along a direction perpendicular to a preset conveying direction X. In some embodiments, when a plurality of active material coatings 22 of a pole piece strip 20 are provided on the same side of a current collector substrate 21, the plurality of active material coatings 22 are moved along the preset conveying direction X, and a pre-lithiation treatment is performed on each active material coating 22, thereby completing the single-sided pre-lithiation treatment of the pole piece strip 20. In other embodiments, when a plurality of active material coatings 22 of a pole piece strip 20 are distributed on opposite sides of a current collector substrate 21, the pole piece strip 20 is moved along the preset conveying direction X, and after all the plurality of active material coatings 22 on one side of the pole piece strip 20 are pre-lithiation treated, the pole piece strip 20 is rewound, and the pole piece strip 20 is moved again along the preset conveying direction X, and after all the plurality of active material coatings 22 on the other side of the pole piece strip 20 are pre-lithiation treated, the double-sided pre-lithiation treatment of the pole piece strip 20 is completed. Optionally, the preset transport direction X is horizontal, and the pre-lithiation surface of the electrolyte layer 121 is a plane parallel to the horizontal direction. In this case, the pre-lithiation cavities 120 of the multiple pre-lithiation units 100 can be vertically arranged above the multiple pre-lithiation platforms 110; or, the pre-lithiation cavities 120 of the multiple pre-lithiation units 100 can be vertically arranged below the multiple pre-lithiation platforms 110. The multiple pre-lithiation cavities 120 arranged on the same side of the multiple pre-lithiation platforms 110 can be arranged side by side in a direction parallel to the preset transport direction X.

[0098] In some embodiments, along a direction perpendicular to the preset conveying direction X, a portion of the pre-lithiation cavities 120 are arranged on the same side of the multiple pre-lithiation platforms 110, and another portion of the pre-lithiation cavities 120 are arranged on the other side of the multiple pre-lithiation platforms 110. In this way, double-sided pre-lithiation can be performed. When the multiple active material coatings 22 of the electrode strip 20 are distributed on opposite sides of the current collector substrate 21, the electrode strip 20 is directly moved along the preset conveying direction X, and the pre-lithiation cavities 120 distributed on opposite sides of the multiple pre-lithiation platforms 110 can perform pre-lithiation treatment on the active material coatings 22 on the corresponding side, thereby improving the pre-lithiation efficiency.

[0099] In some more specific embodiments, when a portion of the pre-lithium cavities 120 are disposed on one side of the plurality of pre-lithium platforms 110 and another portion of the pre-lithium cavities 120 are disposed on the other side of the plurality of pre-lithium platforms 110, the pre-lithium cavities 120 located on the upper and lower sides of the plurality of pre-lithium platforms 110 may be arranged crosswise, that is, each pre-lithium unit 100 has a pre-lithium cavity 120 and a pre-lithium platform 110, and the pre-lithium cavities 120 of two adjacent pre-lithium units 100 are disposed on opposite sides of the pre-lithium platform 110. Optionally, the preset transport direction X is a horizontal direction, and the pre-lithium surface of the electrolyte layer 121 is a plane parallel to the horizontal direction. In this case, the pre-lithium cavities 120 of a portion of the pre-lithium units 100 are disposed vertically above the plurality of pre-lithium platforms 110, and the pre-lithium cavities 120 of the remaining portion of the pre-lithium units 100 are disposed vertically below the plurality of pre-lithium platforms 110.

[0100] In some more specific embodiments, when a portion of the pre-lithium cavities 120 are arranged on one side of multiple pre-lithium platforms 110 and another portion of the pre-lithium cavities 120 are arranged on the other side of the multiple pre-lithium platforms 110, it is also possible that n consecutive pre-lithium cavities 120 are all arranged on the same side of the multiple pre-lithium platforms 110, and n adjacent consecutive pre-lithium cavities 120 are all arranged on the other side of the multiple pre-lithium platforms 110. In this way, n consecutive surfaces to be pre-lithiumed on the same side can be pre-lithiumed at the same time, and then the corresponding surfaces to be pre-lithiumed on the other side can be pre-lithiumed at the same time to complete double-sided pre-lithiation.

[0101] In some embodiments, the strip retracting mechanism of the electrode pre-lithiation equipment 10 includes a control system, and the pre-lithiation unit 100 includes a driving device 130, which is connected to the pre-lithiation cavity 120. The control system is in signal communication with the driving device 130 to control the driving device 130 to drive the pre-lithiation cavity 120 to move, thereby driving the electrolyte layer 121 to move to contact the active material coating 22 for pre-lithiation treatment, and after the pre-lithiation is completed, the driving device 130 is controlled to drive the pre-lithiation cavity 120 to move so that the electrolyte layer 121 is separated from the active material coating 22. The control system is also in signal communication with the preheating platform 210 to control the heating state of the preheating platform 210 to adjust the preheating temperature of the active material coating 22. The control system is also in signal communication with the heating component provided on the pre-lithiation platform 110 to control the heating state of the heating component to adjust the temperature of the active material coating 22 corresponding to the pre-lithiation platform 110.

[0102] In some embodiments, the strip retracting mechanism of the electrode pre-lithiation device 10 includes an unwinding assembly 310 and a rewinding assembly 320 arranged relatively to each other along a preset conveying direction X, and a pre-lithiation unit 100 is provided between the unwinding assembly 310 and the rewinding assembly 320. The control system is also in signal communication with the unwinding assembly 310 and the rewinding assembly 320 respectively to control the unwinding assembly 310 and the rewinding assembly 320 to pull the two ends of the electrode strip 20, thereby tightening the electrode strip 20 between the unwinding assembly 310 and the rewinding assembly 320, and conveying the electrode strip 20 from the unwinding assembly 310 to the rewinding assembly 320, so that the electrode strip 20 is in a stretched state, so that the active material coating 22 is in flat contact with the preheating platform 210 and the pre-lithiation platform 110, thereby improving the pre-lithiation effect and preventing the electrode strip 20 from slacking and causing the tape to shift.

[0103] The unwinding assembly 310 includes an unwinding roller 3101, multiple unwinding rollers 311, an unwinding splicing platform 312, and an unwinding pressure bar 313. The winding assembly 320 includes a winding roller 3202, multiple winding rollers 321, a winding splicing platform 322, and a winding pressure bar 323. The unwinding roller 3101 is used to wind up the electrode strip 20 that has not undergone pre-lithium treatment, and the winding roller 3202 is used to wind up the electrode strip 20 that has undergone pre-lithium treatment. The unwinding roller 311 and the winding roller 321 are used to position and support the electrode strip 20 between the unwinding roller 3101 and the winding roller 3202. The unwinding pressure rod 313 and the unwinding splicing platform 312 act on the electrode strip 20 on one side of the pre-lithium unit 100 and provide a pre-tightening force, and the winding pressure rod 323 and the winding splicing platform 322 act on the electrode strip 20 on the other side of the pre-lithium unit 100 and provide a pre-tightening force. They are used together to perform splicing before the pre-lithium operation. After the pre-lithium operation is completed, some empty current collector substrate 21 can be retained in the electrode pre-lithiation equipment 10, which is convenient for splicing during the next pre-lithium operation.

[0104] In some embodiments, the unwinding assembly 310 further includes an unwinding correction system 314, and the rewinding assembly 320 further includes a rewinding correction system 324. The control system is in signal communication with the unwinding correction system 314 and the rewinding correction system 324, respectively. The control system is used to control the unwinding correction system 314 to act on the electrode strip 20 when the unwinding assembly 310 is unwinding and moving, and adjust the electrode strip 20 to be in a predetermined unwinding position. The rewinding correction system 324 is provided corresponding to the rewinding assembly 320, and the control system is used to control the rewinding correction system 324 to act on the electrode strip 20 when the rewinding assembly 320 is rewinding and moving, and adjust the electrode strip 20 to be in a predetermined rewinding position. The positions of the two ends of the electrode strip 20 are corrected in time by the unwinding correction system 314 and the rewinding correction system 324, so that the electrode strip 20 between the unwinding assembly 310 and the rewinding assembly 320 can be accurately moved to the preheating platform 210 and the pre-lithium platform 110.

[0105] In some embodiments, the strip retracting mechanism of the electrode pre-lithiation equipment 10 also includes a positioning sensing device 500. The control system is in signal communication with the positioning sensing device 500, and controls the positioning sensing device 500 to identify and feedback the positions of the electrode strip 20 and the active material coating 22, so as to obtain the position of the active material coating 22 relative to the preheating platform 210 or the pre-lithiation platform 110, and obtain the position of the electrode strip 20, which is then used to control the unwinding correction system 314 and the rewinding correction system 324 to adjust the position of the electrode strip 20.

[0106] In some embodiments, the unwinding assembly 310 further includes an unwinding tension detection system 315, and the rewinding assembly 320 further includes a rewinding tension detection system 325. The control system is in signal communication with the unwinding tension detection system 315 and the rewinding tension detection system 325, respectively. The control system is configured to control the unwinding tension detection system 315 to detect the unwinding tension applied by the unwinding assembly 310 to the electrode strip 20. The unwinding tension detection system 315 generates an abnormal unwinding tension signal when the unwinding tension is abnormal. The control system adjusts the unwinding tension applied by the unwinding assembly 310 to the electrode strip 20 according to the abnormal unwinding tension signal. The control system is configured to control the rewinding tension detection system 325 to detect the rewinding tension applied by the rewinding assembly 320 to the electrode strip 20. The rewinding tension detection system 325 generates an abnormal rewinding tension signal when the rewinding tension is abnormal. The control system adjusts the rewinding tension applied by the rewinding assembly 320 to the electrode strip 20 according to the abnormal rewinding tension signal. The tension acting on both ends of the electrode strip 20 is obtained through the unwinding tension detection system 315 and the winding tension detection system 325, and then the tension of the electrode strip 20 between the unwinding component 310 and the winding component 320 is indirectly controlled to be appropriate, so that the electrode strip 20 can be in a stretched state and contact the preheating platform 210 and the pre-lithium unit 100 respectively, and prevent the electrode strip 20 from being subjected to excessive tension, which causes the electrode strip 20 to be pulled and deformed.

[0107] In some embodiments, the electrolyte layer 121 includes a solid electrolyte, and the electrolyte layer 121 can be processed into a predetermined shape so as to contact the active material coating 22. Preferably, the material of the solid electrolyte includes Li7La3Zr2O 12 、Li 6.4 La3Ta 0.6 Zr 1.4 O 12 、LiTi2(PO4)3、Li 14 At least one of Zn(GeO4)4, Li2S-P2S5, LiBH4, LiI, Li3PO4, Li2B4O7, lithium nitride phosphate, a lithium ion solid electrolyte containing a polymer, and a lithium ion solid electrolyte doped with β-Al2O3.

[0108] In some embodiments, the pre-lithium chamber 120 further includes a sacrificial electrode, which is used to contact the molten salt and the lithium source R and lose electrons to provide Li + The active material coating 22 embedded in the electrode strip 20 is subjected to electrochemical pre-lithiation treatment. The principle of electrochemical pre-lithiation treatment is as follows: the sacrificial electrode of the pre-lithiation cavity 120 is electrically connected to the positive electrode of the pre-lithiation circuit, and the negative electrode of the pre-lithiation circuit is electrically connected to the metal foil of the electrode strip 20. After power is applied, the Li in the pre-lithiation cavity 120 is + The active material coating 22 is embedded through the electrolyte layer 121. For example, the sacrificial electrode is Zn.

[0109] Positive electrode reaction equation: Zn-xe - =Zn 2+ ;

[0110] Negative electrode reaction equation: xLi + +6C+xe - =Li x C6.

[0111] Preferably, the molten salt includes at least one of LiF, KF, NaF, RbF, CsF, BaF2, LiCl, KCl, NaCl, RbCl, CsCl, BaCl2, LiBr, KBr, NaBr, RbBr, CsBr, BaBr2, LiI, KI, NaI, RbI, CsI, BaI2, LiNO3, KNO3, NaNO3, LiAlCl4, and NaAlCl4;

[0112] Preferably, the lithium source includes at least one of a lithium salt and a lithium alloy; the lithium salt includes at least one of LiF, LiCl, LiI, and LiNO3; and the lithium alloy includes at least one of a Li-Zn alloy, a Li-Sn alloy, a Li-Bi alloy, a Li-Pb alloy, a Li-Cu alloy, and a Li-Al alloy.

[0113] Preferably, the sacrificial electrode is an aluminum electrode, a magnesium electrode, a zinc electrode or an alloy electrode thereof.

[0114] The present application also provides a method for pre-lithiation of a pole piece corresponding to the pole piece pre-lithiation device 10. The method for pre-lithiation of a pole piece includes:

[0115] Step S110: providing a pole piece strip 20, wherein the pole piece strip 20 is coated with an active material coating 22 at intervals;

[0116] Step S120: loading molten salt and lithium source R into the pre-lithium box 123, heating the molten salt and lithium source R to make them molten;

[0117] Step S130: contact the pre-lithiation surface of the electrolyte layer 121 with the active material coating 22 on the pre-lithiation platform 110, and apply a pre-lithiation voltage to the pre-lithiation cavity 120 to perform a pre-lithiation process so that the Li + The active material coating 22 of the electrode strip 20 is embedded through the electrolyte layer 121 .

[0118] The pre-lithiation method of the embodiment of the present application brings the surface of the electrolyte layer 121 into contact with the surface of the active material coating 22, and adjusts the current density parameters of the external circuit through the electrochemical lithium replenishment method to adjust the amount of lithium replenished into the corresponding active material coating 22, so as to achieve a uniform and controllable lithium replenishment effect. In addition, pre-lithiation can also be performed on pole pieces with different lithium densities. In actual production, the size of the pre-lithiation platform 110 and the electrolyte layer 121 can be adjusted accordingly according to the outer dimensions of the active material coating 22 and the spacing between two adjacent active material coatings 22. It is not limited by the size of the active material coating 22, and a pole piece pre-lithiation device 10 with a large width can be developed according to the size of the active material coating 22. Moreover, during the pre-lithiation treatment process, it is only necessary for the electrolyte layer 121 to be in contact with the surface of the active material coating 22, and no other structure is required to participate in the pre-lithiation treatment. The operation is convenient, the process is simple, and the pre-lithiation efficiency can be effectively improved.

[0119] In some embodiments, applying a pre-lithium voltage to the pre-lithium cavity 120 in step S130 includes providing a pre-lithium circuit, electrically connecting the positive electrode of the pre-lithium circuit to the pre-lithium cavity 120, electrically connecting the negative electrode of the pre-lithium circuit to the current collector of the electrode strip 20, and contacting the pre-lithium surface of the electrolyte layer 121 with the active material coating 22 to apply the pre-lithium voltage across the positive and negative electrodes. Specifically, when the pre-lithium cavity 120 includes a sacrificial electrode, the positive electrode of the pre-lithium circuit is electrically connected to the sacrificial electrode.

[0120] In some embodiments, the pre-lithiation treatment conditions include: the current density applied to the pre-lithiation chamber 120 by the pre-lithiation circuit is β, 20 mA / cm 2 ≤β≤56mA / cm 2 , for example, β can be 32 mA / cm 2 , 25mA / cm 2 、30mA / cm 2 、36mA / cm 2 , 48mA / cm 2 , 56mA / cm 2 Or any of the above two ranges, by selecting the current density β applied to the pre-lithium cavity 120 within the above range, it is convenient to control the Li + The migration rate of Li + The active material coating 22 is uniformly embedded, and the pre-lithiation efficiency is high. When the current density β is less than 20mA / cm2 When the current density β is too small, the pre-lithiation time will be prolonged, resulting in the risk of decomposition of the adhesive in the active material coating 22. At the same time, there is also the problem of low pre-lithiation rate, resulting in low pre-lithiation efficiency. When the current density β is greater than 56 mA / cm 2 When the current density β is too large, Li + The migration rate is greater than that of Li + The rate of Li + Point-like accumulation makes effective pre-lithiation impossible and also causes the adhesive to decompose and fail, and the active material coating 22 to stick and fall off. Preferably, 35mA / cm 2 ≤β≤45mA / cm 2 .

[0121] In some embodiments, the conditions for pre-lithium treatment include: the pre-lithium voltage M applied to the pre-lithium chamber 120 by the pre-lithium circuit is 2.6V≤M≤4.5V, for example, M can be 2.6V, 2.9V, 3.2V, 3.6V, 4.2V, 4.5V or any range thereof. By selecting the pre-lithium voltage M applied to the pre-lithium chamber 120 within the above range, the Li + When the pre-lithiation voltage M is less than 2.6V, the pre-lithiation current density is small and the pre-lithiation time is long. When the pre-lithiation voltage M is greater than 4.5V, the molten salt will undergo side reaction decomposition. Preferably, 3.3V≤V≤3.8V.

[0122] In some embodiments, the pre-lithium treatment conditions include: the pre-lithium temperature applied to the pre-lithium chamber 120 by the pre-lithium circuit is T x , where the pre-lithium temperature T x It can be the temperature of the pre-lithium platform 110, 110℃≤T x ≤130℃, for example, T x The temperature can be 110°C, 114°C, 116°C, 118°C, 120°C, 125°C, 130°C or any range thereof. x In the above range, the temperature of the active material coating 22 can be kept within an appropriate range, which is convenient for Li + Move smoothly, making Li + The active material coating 22 can be smoothly embedded. x If the temperature is lower than 110℃, the molten salt dissolution effect close to the pre-lithiation surface is poor, and effective pre-lithiation cannot be performed. In addition, the temperature of the active material coating 22 is too low, and the Li + It is difficult to enter the active material coating 22 and to perform effective pre-lithiation. xWhen the temperature is greater than 130° C., the temperature of the active material coating 22 is too high, which may easily lead to failure and decomposition of the adhesive in the active material coating 22 , thereby causing the active material coating 22 to fall off. In addition, when the current collector is a copper foil, it may also easily lead to oxidation of the copper foil.

[0123] Preferably, 110°C ≤ T x ≤120℃, within this temperature range, the dissolution effect of molten salt is better, which improves the Li + activity, making Li + It can be smoothly embedded in the active material coating 22 for pre-lithiation, and in the pre-lithiation process, the organic material sticking phenomenon is avoided, the active material coating is stable, and a good pre-lithiation effect is obtained.

[0124] In some embodiments, in step S120, the molten salt and the lithium source R are heated to a molten state, including: the heating layer of the pre-lithium cavity 120 heats the molten salt and the lithium source R inside the pre-lithium cavity 120 to a melting temperature Ty, 110°C ≤ T y ≤120℃, so that the molten salt and lithium source R are in a molten state, for example, T y The melting temperature T can be 110°C, 112°C, 115°C, 118°C, 120°C or any range thereof. y In the above range, the molten salt and the lithium source R can be fully melted to increase the Li + The liquidity of Li + It can smoothly pass through the electrolyte layer 121 and enter the active material coating layer 22 .

[0125] In some embodiments, during the pre-lithiation process of step S130, the pre-lithiation surface of the electrolyte layer 121 is brought into contact with the active material coating 22 on the pre-lithiation platform 110, and the pressure applied by the electrolyte layer 121 to the pre-lithiation surface of the active material coating 22 is P, 0.1 kg / cm 2 ≤P≤20Kg / cm 2 For example, P can be 0.1 Kg / cm 2 , 1.0Kg / cm 2 、3.5Kg / cm 2 , 5Kg / cm 2 、10Kg / cm 2 、15Kg / cm 2 , 20Kg / cm 2 Or any range of the above two. By selecting the pressure P applied by the electrolyte layer 121 to the surface to be pre-lithiated within the above range, the electrolyte layer 121 can be closely attached to the surface to be pre-lithiated, so that the Li +It can smoothly enter the active material coating 22 and prevent the electrolyte layer 121 and the active material coating 22 from being crushed due to excessive pressure between the electrolyte layer 121 and the active material coating 22 .

[0126] In some embodiments, before performing the pre-lithium treatment, the process also includes: using a strip retracting mechanism to transport the active material coating 22 of the electrode strip 20 to the preheating platform 210 of the preheating unit 200, and after preheating treatment, transporting it to the pre-lithium unit 100 along a preset conveying direction X, thereby saving time and improving pre-lithium efficiency.

[0127] In some embodiments, the preheat treatment temperature Tc is 105°C ≤ Tc ≤ 125°C. For example, Tc can be 105°C, 110°C, 112°C, 115°C, 120°C, 125°C, or any range thereof. By selecting the preheat treatment temperature Tc within the above range, the active material coating 22 reaching the pre-lithiation platform 110 has a suitable temperature, thereby allowing for efficient pre-lithiation treatment.

[0128] In some embodiments, multiple pre-lithiation platforms 110 are arranged along a preset conveying direction X, and multiple pre-lithiation cavities 120 are provided on the same side of the multiple pre-lithiation platforms 110 to convey the active material coatings 22 coated at intervals on the electrode strip 20 to the multiple pre-lithiation platforms 110 for single-sided pre-lithiation. Specifically, when the electrode strip 20 is coated with active material coatings 22 on both sides, the multiple active material coatings 22 coated at intervals on one side of the electrode strip 20 are first conveyed to the multiple pre-lithiation platforms 110 for single-sided pre-lithiation. After the overall pre-lithiation of that side of the electrode strip is completed, the electrode strip 20 is rewound, and the multiple active material coatings 22 coated at intervals on the other side of the electrode strip 20 are conveyed to the multiple pre-lithiation platforms 110 for single-sided pre-lithiation, and the other side is subjected to overall pre-lithiation.

[0129] In some embodiments, multiple pre-lithiation platforms 110 are arranged along a preset conveying direction X, and a portion of the pre-lithiation cavity 120 is provided on one side of the multiple pre-lithiation platforms 110, and a portion of the pre-lithiation cavity 120 is also provided on the other side. The active material coating 22 coated at intervals on the electrode strip 20 is transported to the multiple pre-lithiation platforms 110 for double-sided pre-lithiation, that is, when the electrode strip is transported, pre-lithiation is performed on both sides.

[0130] In the embodiment of the present application, the electrode strip 20 can be cut and used as a negative electrode in a battery. The material of the electrode strip 20 is not particularly limited in the embodiment of the present application, and any electrode strip 20 that can be used in the art is suitable for this application.

[0131] The following describes the electrode pre-lithiation method corresponding to the electrode pre-lithiation device 10 in conjunction with specific embodiments. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation method is within the scope of this application.

[0132] Example

[0133] Below, taking lithium-ion batteries as an example, examples and comparative examples are given to more specifically illustrate the implementation of the pole piece pre-lithiation method corresponding to the pole piece pre-lithiation device 10 of the present application. Those skilled in the art will understand that the pole piece pre-lithiation method described in this application is only an example, and any other suitable pole piece pre-lithiation method is within the scope of this application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0134] Example 1

[0135] Preparation of negative electrode sheet

[0136] (1) Providing a pole piece strip 20.

[0137] Silicon-carbon material 650-K, conductive carbon black SuperP, styrene-butadiene rubber emulsion SBR driver 130 (BM451B), and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 95:2:1.5:1.5, added to deionized water, and stirred evenly in a vacuum mixer to produce a negative electrode slurry. The negative electrode slurry was evenly coated on one surface of a 10μm-thick negative electrode current collector copper foil. The negative electrode slurry was then dried at 95°C and cold-pressed to produce a negative electrode strip 20 coated on one side with a negative electrode active material coating 22. The above steps were then repeated on the other surface of the copper foil to produce a negative electrode strip 20 coated on both sides with a negative electrode active material coating 22.

[0138] like Figure 6 As shown, multiple negative electrode active material coatings 22 are provided on the same side of the negative electrode current collector. Adjacent negative electrode active material coatings 22 are spaced apart, and the multiple layers of active material coatings 22 provided on both sides of the current collector correspond one to one. Along the length of the negative electrode active material coatings 22, the current collector has a leading empty foil region and a trailing empty foil region. Neither the leading empty foil region nor the trailing empty foil region is coated with negative electrode active material coating 22.

[0139] The length of each negative electrode active material coating 22 is 75 mm, the width is 50 mm, and the compaction density of the negative electrode active material coating 22 is 1.5 g / cm 3 The distance between two adjacent negative electrode active material coatings 22 along their length direction is 25 mm.

[0140] (2) Adoption Figure 5 The electrode pre-lithiation equipment 10 performs pre-lithiation treatment on the electrode strip 20. Figure 5 The electrode pre-lithiation device 10 includes two groups of pre-lithiation units 100 and two groups of preheating platforms 210, and the pre-lithiation chambers 120 of the two groups of pre-lithiation units 100 are located on the same side of the pre-lithiation platform 110 in the horizontal direction.

[0141] use Figure 5 The steps of the electrode pre-lithiation device 10 performing pre-lithiation treatment on the electrode strip 20 are as follows:

[0142] a. Turn on the dehumidification system in the pre-lithium drying room and control the dew point between -60℃ and -80℃.

[0143] b. Mix NaAlCl4 and LiAlCl4 in a mass ratio of 1:1 to obtain molten salt. Mix the lithium source LiCl and the molten salt in a mass ratio of 1:7.5, and then place the molten salt and the lithium source R in the main box 1231 and the sub-box 1232. Start the heating layer outside the main box 1231 and the sub-box 1232 to heat the molten salt and the lithium source R to the melting temperature T y The temperature is 115°C, so that the molten salt and the lithium source R are in a molten state.

[0144] c. Install the wound negative electrode strip 20 on the unwinding assembly 310, and pull the empty foil area of the head of the current collector through the preheating platform 210 and the pre-lithium platform 110 in sequence, and install it on the winding assembly 320, so that the negative electrode strip 20 is in a tensioned state under the traction of the unwinding assembly 310 and the winding assembly 320.

[0145] d. Start the unwinding assembly 310 and the rewinding assembly 320 to convey the negative electrode sheet strip 20 along the preset conveying direction X, and start the unwinding tension detection system 315 and the rewinding tension detection system 325 to automatically detect and adjust the tension acting on the negative electrode sheet strip 20; and start the unwinding correction system 314 and the rewinding correction system 324 to automatically detect and adjust the negative electrode sheet strip 20 to ensure that there is no deviation or wrinkle during the conveying process.

[0146] Furthermore, the positioning sensing device 500 is activated to automatically detect and adjust the first negative electrode active material coating 22 a on the upper and lower surfaces of the current collector substrate 21 to correspond to the first preheating platform 210 and the second negative electrode active material coating 22 b to correspond to the second preheating platform 210 .

[0147] e. Start the preheating platform 210, which heats the corresponding negative electrode active material coating 22 to a temperature Tc of 115°C. After the preheating is completed, the negative electrode strip 20 is conveyed, and the first negative electrode active material coating 22a on the upper surface of the current collector is transported to the pre-lithium platform 110 corresponding to the second pre-lithium unit 102, and the second negative electrode active material coating 22b on the upper surface corresponds to the pre-lithium platform 110 of the first pre-lithium unit 101. The pre-lithium platform 110 heats the corresponding negative electrode active material coating 22 to a pre-lithium temperature of Tc. xThe temperature is 115° C. At the same time, the third negative electrode active material coating 22 c and the fourth negative electrode active material coating 22 d on the upper surface of the current collector substrate 21 respectively arrive at the first preheating platform 210 and the second preheating platform 210 for preheating treatment.

[0148] f. Start the driving devices 130 of the first pre-lithium unit 101 and the second pre-lithium unit 102. The driving device 130 drives the electrolyte layer 121 of the corresponding pre-lithium cavity 120 to adhere to the surface of the negative electrode active material coating 22 on each pre-lithium platform 110. The pressure P of the electrolyte layer 121 on the corresponding negative electrode active material coating 22 to be pre-lithium is 3.5Kg / cm 2 At this time, the pre-lithium circuit is started to apply a pre-lithium voltage to each pre-lithium cavity 120 to perform the pre-lithium treatment. The current density of the pre-lithium treatment is 45 mA / cm 2 , the pre-lithium voltage M is 3.8V, and the pre-lithium time Ts is 1.7min.

[0149] g. After the pre-lithiation treatment is completed, the driving devices 130 of the first pre-lithiation unit 101 and the second pre-lithiation unit 102 are controlled to drive the electrolyte layer 121 of the pre-lithiation chamber 120 to separate from the negative electrode active material coating 22, and the pre-lithiation chamber 120 is reset. Then, the third negative electrode active material coating 22c and the fourth negative electrode active material coating 22d on the upper surface of the current collector substrate 21 are transported to the corresponding pre-lithiation platforms 110 of the second pre-lithiation unit 102 and the first pre-lithiation unit 101, respectively. The third negative electrode active material coating 22c and the fourth negative electrode active material coating 22d are pre-lithiation treated according to the same pre-lithiation treatment conditions as the first negative electrode active material coating 22a and the second negative electrode active material coating 22b. At the same time, the last two active material coatings 22 on the upper surface of the current collector are moved to the preheating platform 210 for preheating. The above process is repeated for the remaining active material coatings 22, and the operation is continued until the pre-lithiation of one side of the negative electrode strip 20 is completed.

[0150] h. After rewinding the negative electrode strip 20 that has been pre-lithiated on the upper surface of the current collector, repeat steps (d) to (g) to pre-lithiate the active material coating 22 on the lower surface of the current collector substrate 21 until all the negative electrode active material coatings 22 of the electrode strip 20 have been pre-lithiated, and the pre-lithiation treatment of the electrode strip 20 is completed.

[0151] (3) Cutting the electrode strip 20 at the spacer area 221 between two adjacent negative electrode active material coatings 22 to form a plurality of negative electrode sheets of predetermined specifications.

[0152] Then, the obtained negative electrode sheet is used as a pre-lithium negative electrode sheet to assemble a half cell or a full cell.

[0153] Example 2

[0154] The difference from Example 1 is:

[0155] In the step (2) of preparing the negative electrode sheet, the Figure 1 The electrode pre-lithiation equipment 10 performs double-sided pre-lithiation treatment on the electrode strip 20. Figure 1 The electrode pre-lithiation equipment 10 includes two groups of pre-lithiation units 100 and a group of preheating platforms 210, and the pre-lithiation cavities 120 of the two groups of pre-lithiation units 100 are located on different sides of the pre-lithiation platform 110 in the horizontal direction; and in step (2) of preparing the negative electrode, the steps after step c are different from those in Example 1.

[0156] The steps after step c in Example 2 are as follows:

[0157] d. Start the positioning sensing device 500 to automatically detect and adjust the first negative electrode active material coating 22 a on the upper and lower surfaces of the current collector substrate 21 to correspond to the preheating platform 210 .

[0158] e. Start the preheating platform 210, which heats the first negative electrode active material coating 22a on the upper and lower surfaces of the corresponding current collector to a temperature Tc of 110°C. After the first negative electrode active material coating 22a is preheated, the negative electrode strip 20 is moved, and the first negative electrode active material coating 22a on the upper surface of the current collector is transported to the pre-lithium platform 110 corresponding to the first pre-lithium unit 101. The pre-lithium platform 110 heats the corresponding negative electrode active material coating 22 to a pre-lithium temperature Tc of 110°C. x The temperature is 115° C. At the same time, the second negative electrode active material coatings 22 b on the upper and lower surfaces of the current collector substrate 21 arrive at the preheating platform 210 for preheating.

[0159] f. Start the driving device 130 of the first pre-lithium unit 101, and the driving device 130 drives the electrolyte layer 121 of the pre-lithium cavity 120 to adhere to the surface of the first negative electrode active material coating 22a on the upper surface of the current collector substrate 21. The pressure P of the electrolyte layer 121 on the first negative electrode active material coating 22a on the upper surface of the current collector to be pre-lithium is 3.5Kg / cm 2 At this time, the pre-lithium circuit is started to apply a pre-lithium voltage to the pre-lithium cavity 120 of the first pre-lithium unit 101 to perform the pre-lithium treatment. The current density of the pre-lithium treatment is 36.4 mA / cm 2 , the pre-lithium voltage M is 3.8V, and the pre-lithium time Ts is 2.1min.

[0160] g. After the pre-lithiation treatment of the first negative electrode active material coating 22a on the upper surface of the current collector substrate 21 is completed, the driving device 130 of the first pre-lithiation unit 101 drives the electrolyte layer 121 of the pre-lithiation cavity 120 to separate from the first negative electrode active material coating 22a on the upper surface of the current collector, and resets the pre-lithiation cavity 120.

[0161] Then, the first negative electrode active material coating 22a on the lower surface of the current collector substrate 21 is moved to the corresponding pre-lithium platform 110 of the second pre-lithium unit 102, and the driving device 130 of the second pre-lithium unit 102 is started. The driving device 130 drives the electrolyte layer 121 of the pre-lithium cavity 120 to fit with the surface of the first negative electrode active material coating 22a on the lower surface of the current collector substrate 21. The pressure P of the electrolyte layer 121 on the surface to be pre-lithium of the first negative electrode active material coating 22a on the lower surface of the current collector substrate 21 is 3.5Kg / cm 2 . At this time, the pre-lithium circuit is started to apply a pre-lithium voltage to the pre-lithium cavity 120 of the second pre-lithium unit 102 for pre-lithium treatment. The current density of the pre-lithium treatment is 36.4 mA / cm2, the pre-lithium voltage M is 3.8 V, and the pre-lithium time Ts is 2.1 min. At the same time, the second negative electrode active material coating 22b on the upper surface of the current collector substrate 21 moves to the corresponding first pre-lithium unit 101 for pre-lithium treatment, and the third negative electrode active material coating 22c on the current collector substrate 21 moves to the corresponding preheating platform 210 for preheating treatment.

[0162] h. Repeat the steps (d) to (g) above for the remaining active material coatings 22 until all the negative electrode active material coatings 22 of the electrode strip 20 are pre-lithium treated, thus completing the pre-lithium treatment of the electrode strip 20.

[0163] (3) Cutting the electrode strip 20 at the spacer area 221 between two adjacent negative electrode active material coatings 22 to form a plurality of negative electrode sheets of preset specifications.

[0164] Then, the obtained negative electrode sheet is used as a pre-lithium negative electrode sheet to assemble a half cell or a full cell.

[0165] The difference between Examples 3 to 9 and Example 1 is that the current density β of the pre-lithiation treatment is different. The specific parameters are shown in Table 1.

[0166] The difference between Example 10 to Example 15 and Example 1 is that the pre-lithiation voltage M of the pre-lithiation treatment is different. The specific parameters are shown in Table 1.

[0167] The difference between Example 16 to Example 21 and Example 1 is that the pre-lithiation temperature Tx of the pre-lithiation treatment is different. The specific parameters are shown in Table 1.

[0168] Example 22 differs from Example 1 in that the size of the negative electrode active material coating 22 of the electrode strip used is different, wherein the negative electrode active material coating 22 is 355 mm long and 80 mm wide.

[0169] Comparative Example 1

[0170] The difference from Example 1 is that the negative electrode plate obtained in step 1 is directly used as a non-pre-lithium negative electrode plate to assemble a half-cell or a full cell.

[0171] Comparative Example 2

[0172] The difference from Example 1 is that the calendering method is used for pre-lithiation in step (2) of preparing the negative electrode sheet.

[0173] The calendering method for pre-lithiation includes: cutting the negative electrode strip 20 obtained in step (1) of Example 1 to form a plurality of negative electrode sheets of the same specifications as Example 1. 2 , pre-lithium time 1.7min) pre-lithium amount, calculated per cm 2 The negative electrode active material coating uses a 6.2 μm ultra-thin lithium film, which is bonded to the surface of the negative electrode active material coating 22 of each negative electrode plate to obtain a composite pre-lithium negative electrode plate.

[0174] Comparative Example 3

[0175] The difference from Example 22 is that the calendering method is used for pre-lithiation in step (2) of preparing the negative electrode sheet. During the pre-lithiation process, it was found that the pressure on both sides along the length of the active material coating was uneven, the bonding force was poor, and it was easy to peel off and fall off.

[0176] The performance of the pre-lithium negative electrode sheets obtained in each embodiment and comparative example was tested in the following directions.

[0177] 1. Initial Coulombic efficiency test of half-cell:

[0178] 1. Preparation of half-cell

[0179] First, place a gasket (φ15.8mm thickness 0.5mm) in the negative electrode shell, then place a lithium sheet (φ14 thickness 1.5mm), drip 40 microliters of electrolyte and place the diaphragm (φ16mm), then drip 40 microliters of electrolyte and place the negative electrode sheet; then place a gasket (φ15.8mm thickness 0.5mm) and a spring (funnel-shaped, φ15.4 thickness 1.1mm), and finally cover the positive electrode shell, flip the button battery over and place it in the sealing machine mold for sealing and pressing, with a pressure of 50kg / cm 2 Maintain the pressure for 60 seconds to obtain a button cell, which can be tested after standing for 12 hours. The electrolyte used is CLUDE MA-EN-EL-00241.

[0180] The diaphragm used is "Celgard2400" diaphragm with a thickness of 6.2μm.

[0181] The outer packaging uses the steel shell of the CR2032 button battery of CROOD.

[0182] 2. First Coulombic efficiency test

[0183] First coulombic efficiency test of half-cell: buckle the negative electrode side - lithium sheet / buckle the positive electrode side - negative electrode sheet;

[0184] At 25±2°C, the battery was left uncharged for 12 h, discharged at a constant current (CC) of 0.13 mA to 0.05 V, with the discharge capacity recorded as C1 mAh. After leaving the battery for 10 min, the battery was charged at a constant current (CC) of 0.13 mA to 3 V, with the charge capacity recorded as C2 mAh, and the battery was terminated. The first coulombic efficiency of the half-cell, FE, was calculated as: C2 / C1×100%.

[0185] 2. Initial Coulombic Efficiency Test of Full Battery

[0186] 1. Preparation of full battery

[0187] (1) Preparation of positive electrode sheet

[0188] Nickel-cobalt-lithium ternary material NCM811, conductive carbon black SuperP, and polyvinylidene fluoride PVDF5300 (preheated platform 210) were mixed in a mass ratio of 96:2:2, added to a methyl pyrrolidone solution, and stirred evenly in a vacuum mixer to produce a positive electrode slurry. The positive electrode slurry was evenly coated on one surface of a 12μm thick positive electrode current collector aluminum foil. The mixture was then dried at 110°C and cold-pressed to produce a positive electrode strip 20 coated on one side with an 85μm thick positive electrode active material coating 22. The above steps were then repeated on the other surface of the foil to produce a positive electrode strip 20 coated on both sides with a positive electrode active material coating 22.

[0189] The positive electrode strip 20 is cut to obtain positive electrode sheets of the same specifications as the negative electrode sheets in Example 1. The compaction density of the positive electrode active material coating 22 is 3.0 g / cm 3 .

[0190] (2) Assembly of the full battery

[0191] First, place a gasket (φ15.8mm, thickness 0.5mm) in the negative electrode shell, then place the negative electrode sheet (φ14mm), and drip the electrolyte.

[0192] After adding 40 microliters of electrolyte, place the diaphragm (φ16mm), then drop 40 microliters of electrolyte and place the positive electrode (φ12mm); then place a pad

[0193] Sheet (φ15.8mm thickness 0.5mm) and spring (funnel-shaped, φ15.4 thickness 1.1mm), and finally cover the positive shell, turn the buckle over and place it on the

[0194] The sealing machine performs sealing and pressing in the mold with a pressure of 50kg / cm2 Maintain the pressure for 60 seconds to obtain a full button battery, which can be tested after standing for 12 hours.

[0195] Among them, the electrolyte selected is the electrolyte of Kruder MA-EN-EL-00241.

[0196] The diaphragm used is "Celgard2400" diaphragm with a thickness of 6.2μm.

[0197] The outer packaging uses the steel shell of the CR2032 button battery of CROOD.

[0198] 2. First Coulombic efficiency test

[0199] First coulombic efficiency test of the whole battery: buckle the negative electrode side - negative electrode sheet / buckle the positive electrode side - positive electrode sheet;

[0200] At 25±2℃, let it stand for 12h, then charge it at 0.02C constant current (CC) to 4.3V, the charging capacity is recorded as C2mAh, let it stand for 10min, then discharge it at 0.02C constant current (CC) to 2.75V, the discharge capacity is recorded as C1mAh;

[0201] The first coulombic efficiency of the full battery FE = C1 / C2×100%.

[0202] 3. Specific capacity test of full battery

[0203] A coin cell assembled using the same method as used in the first Coulombic efficiency test.

[0204] Specific capacity test: Constant current charge and discharge test at 25±2℃ / 2.75V-4.2V voltage range.

[0205] During the first discharge process, discharge at a constant current rate of 0.02C to 2.75V. After standing still until the voltage returns to a stable value, discharge at a constant current rate of 40μA to 2.75V. After standing still until the voltage returns to a stable value, discharge at a constant current rate of 10μA to 2.75V. During the charging process, discharge at a constant current rate of 0.02C.

[0206] Charge to 4.2V, completing the first charge and discharge cycle; then discharge the battery at a constant current rate of 0.02C to 2.75V, and let it stand until the voltage returns to a stable state.

[0207] After the value is set, discharge it at a constant current of 40μA to 2.75V. Let it stand until the voltage returns to a stable value, then discharge it at a constant current of 10μA to 2.75V.

[0208] The charging process is carried out at a constant current of 0.02C to 4.2V, completing the second cycle, and obtaining the charging and discharging curves of the second charge and discharge cycle.

[0209] In the discharge curve of the second charge and discharge cycle, the discharge capacity (mAh) in the voltage range of 3.0V-4.2V is divided by the negative electrode activity in the negative electrode sheet.

[0210] The mass (g) of the material coating 22 is recorded as the actual discharge specific capacity (unit: mAh / g) of the negative electrode active material coating 22 at 3.0V-4.2V.

[0211] Batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in Table 1.

[0212] Table 1

[0213]

[0214] Coulombic efficiency refers to the ratio of a battery's discharge capacity to its charge capacity during the cycle. For negative electrodes, it reflects the ratio of the negative electrode's lithium removal capacity to the lithium insertion capacity (in this application, the ratio is discharge capacity / charge capacity for a full battery, and charge capacity / discharge capacity for a half-cell). A higher coulombic efficiency indicates better charge and discharge performance. Specific capacity refers to the capacity per unit weight or unit volume of a battery. A higher specific capacity indicates a higher capacity negative electrode.

[0215] According to the comparison of Examples 1 to 22 in Table 1 with Comparative Example 1, it can be seen that the negative electrode plates prepared by the electrode plate pre-lithiation method of the embodiments of the present application have good first coulombic efficiency regardless of whether they are used in half-cells or full batteries. In addition, the full battery obtained in Example 1 has a higher specific capacity, indicating that the negative electrode plate prepared in Example 1 is used in the battery, and the battery has good charge and discharge performance.

[0216] Comparison of Examples 1 to 22 with Comparative Example 2 shows that when the pre-lithiation area is small, the present process can achieve similar results to the calendering method. When further adjusting the parameters of the present process, such as current density, pre-lithiation voltage, and pre-lithiation temperature, the first coulombic efficiency and specific capacity in the examples are further improved. When the area to be pre-lithiation increases, the effect of the calendering method deteriorates, as shown in Comparative Example 3.

[0217] According to Example 1 and Example 2 in Table 1, the negative electrode sheets prepared by double-sided pre-lithiation in different ways are applied to batteries, and the batteries have good charge and discharge performance.

[0218] It can be seen from Examples 3 to 9 of Table 1 that:

[0219] When the current density is 20 mA / cm 2 ~56mA / cm 2When the pre-lithiation time is 2.9min~1.4min, the half-electric first coulombic efficiency is above 72%, the full-electric first coulombic efficiency is above 90%, and the specific capacity of the full battery is above 394.9mAh / g, which shows that a good pre-lithiation effect is achieved; furthermore, the current density is 35mA / cm 2 -40 mA / cm 2 The pre-lithiation efficiency (pre-lithiation time 2.2min~1.9min) is moderate, the half-electric first coulombic efficiency is 75.02%~76.24% and the full-electric first coulombic efficiency is 93.06%~94.37%, both of which are relatively high. At the same time, the specific capacity of the whole battery is also improved by 408.60mAh / g~414.35mAh / g.

[0220] It can be seen from Examples 10 to 15 of Table 1 that:

[0221] When the pre-lithium voltage is 2.6V~4.5V, the first coulombic efficiency of half-cell is above 70.95%, the first coulombic efficiency of full-cell is above 90.39%, and the specific capacity of the full battery is above 396.87mAh / g, which shows that a good pre-lithium effect is achieved. Furthermore, the pre-lithium time at the pre-lithium voltage of 3.3V~3.5V is 2.1min~1.9min, which is lower than the pre-lithium time of 2.9min~2.7min corresponding to the pre-lithium voltage of 2.6V~3.0V. The pre-lithium efficiency is high, and when the pre-lithium voltage is 3.3V~3.5V, the first coulombic efficiency of the half-cell, the first coulombic efficiency of the full battery and the specific capacity of the full battery are all high, indicating that the pre-lithium effect is better.

[0222] It can be seen from Examples 16 to 20 in Table 1 that:

[0223] When the pre-lithiation temperature was 105°C, the initial pre-lithiation current was 0.2 mA and continued for 7 minutes without any increase. Inspection found that the molten salt was sandy and had not reached a good melting state, resulting in poor pre-lithiation. When the pre-lithiation temperature was between 125°C and 130°C, problems such as foil oxidation and sticking occurred, indicating that too high a pre-lithiation temperature would affect the electrode. When the pre-lithiation temperature was in the range of 110°C to 120°C, the first coulombic efficiency of the half-cell, the first coulombic efficiency of the full cell, and the specific capacity of the full cell were all high, indicating that the pre-lithiation effect was good when the pre-lithiation temperature was between 110°C and 120°C.

[0224] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0225] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A pole piece pre-lithiation device, characterized in that: It includes a pre-lithium unit and a strip retracting and releasing mechanism, wherein the pre-lithium unit includes a pre-lithium platform and a pre-lithium cavity; The pre-lithium platform is used to carry the pole piece strips, and the pole piece strips are coated with active material coatings at intervals; The pre-lithium cavity is arranged corresponding to the pre-lithium platform, and the pre-lithium cavity includes a pre-lithium box, a heating structure and an electrolyte layer provided at the front end of the pre-lithium box, the electrolyte layer is a solid electrolyte, and the interior of the pre-lithium box has a storage space for accommodating molten salt and a lithium source, the heating structure is used to heat the molten salt and the lithium source into a molten state, and the surface of the electrolyte layer is a pre-lithium surface, which is used to contact the active material coating on the pre-lithium platform so that when the pre-lithium voltage is loaded, the Li+ in the pre-lithium cavity passes through the electrolyte layer and is embedded in the active material coating; The strip retracting and unwinding mechanism includes a control system, and the pre-lithium unit includes a driving device, which is connected to the pre-lithium cavity. The control system is in signal communication with the driving device to control the driving device to drive the pre-lithium cavity to move, thereby driving the electrolyte layer to move to contact the active material coating for pre-lithium treatment, and after the pre-lithium is completed, the driving device is controlled to drive the pre-lithium cavity to move so that the electrolyte layer is separated from the active material coating.

2. The electrode pre-lithiation device according to claim 1, characterized in that: The pre-lithium platform includes a heating component, and the heating component is used to heat the active material coating on the pre-lithium platform; and / or, The heating structure in the pre-lithium cavity includes a heating layer arranged outside the pre-lithium box, and the heating layer is used to heat the molten salt and lithium source inside the pre-lithium box.

3. The electrode pre-lithiation equipment according to claim 1, characterized in that: The pre-lithium box includes a main box and a sub-box connected to the main box. The molten salt and lithium source are injected into the main box through the sub-box. The electrolyte layer is arranged at the front end of the main box.

4. The electrode pre-lithiation device according to claim 3, characterized in that: The sub-box is located above the main box, the sub-box is connected to the main box through a linear pipe, and the molten salt and lithium source in the main box are above the electrolyte layer; or The sub-box is located on the side of the main box, and the sub-box is connected to the main box through a zigzag pipe. The molten salt and lithium source in the main box are below the electrolyte layer, and the liquid level of the molten salt and lithium source in the sub-box is higher than the liquid level of the molten salt and lithium source in the main box.

5. The electrode pre-lithiation equipment according to claim 3, characterized in that: The pre-lithium cavity further includes a gas release valve; The air release valve is installed on the main box body, and the air release valve is communicated with the main storage space formed by the main box body to discharge the gas in the main storage space; or, The air release valve is installed on the sub-box body, and the air release valve is communicated with the sub-accommodation space enclosed by the sub-box body to discharge gas in the sub-accommodation space.

6. The electrode pre-lithiation equipment according to claim 1, characterized in that: There are a plurality of pre-lithium units, and the plurality of pre-lithium units are arranged at intervals along a preset conveying direction.

7. The electrode pre-lithiation device according to claim 6, characterized in that: The plurality of pre-lithium units include a plurality of pre-lithium platforms and a plurality of pre-lithium cavities; Wherein, a plurality of the pre-lithium platforms are sequentially spaced apart along the preset conveying direction; Along a direction perpendicular to the preset conveying direction, a plurality of the pre-lithiation cavities are arranged on the same side of the pre-lithiation platform; or, Along a direction perpendicular to the preset conveying direction, a portion of the pre-lithium cavities are arranged on the same side of the pre-lithium platform, and another portion of the pre-lithium cavities are arranged on the other side of the pre-lithium platform.

8. The electrode pre-lithiation device according to claim 7, characterized in that: When a portion of the pre-lithium cavities are located on one side of the pre-lithium platform and another portion of the pre-lithium cavities are located on the other side of the pre-lithium platform, two adjacent pre-lithium cavities are located on different sides of the pre-lithium platform.

9. The electrode pre-lithiation device according to claim 6, characterized in that: The preset transport direction is a horizontal direction, and the pre-lithiation surface of the electrolyte layer is a plane parallel to the horizontal direction.

10. The electrode pre-lithiation equipment according to claim 1, characterized in that: The electrode pre-lithiation equipment further includes a preheating unit; The preheating unit includes a preheating platform for carrying the pole piece strip; The strip retracting mechanism is used to sequentially transport the active material coating on the electrode strip along a preset transport direction to the preheating platform and the pre-lithium platform; Wherein, the preheating platform is used to heat the active material coating on the preheating platform.

11. The electrode pre-lithiation device according to claim 1, characterized in that: The pre-lithium cavity further includes a sacrificial electrode, which is used to contact the molten salt and the lithium source.

12. The electrode pre-lithiation method corresponding to the electrode pre-lithiation device according to any one of claims 1 to 11, characterized in that: include: Providing a pole piece strip, wherein the pole piece strip is coated with an active material coating at intervals; Adding molten salt and lithium source into the pre-lithium box, and heating the molten salt and lithium source to make them molten; The pre-lithiation surface of the electrolyte layer is brought into contact with the active material coating on the pre-lithiation platform, and a pre-lithiation voltage is applied to perform pre-lithiation treatment so that the Li+ in the pre-lithiation cavity passes through the electrolyte layer and is embedded in the active material coating of the electrode strip.

13. The electrode pre-lithiation method according to claim 12, characterized in that: Applying a pre-lithium voltage comprises: A pre-lithium circuit is provided, the positive electrode of the pre-lithium circuit is electrically connected to the pre-lithium cavity, the negative electrode is electrically connected to the current collector of the electrode strip, and the pre-lithium surface of the electrolyte layer is in contact with the active material coating to apply a pre-lithium voltage.

14. The electrode pre-lithiation method according to claim 12, characterized in that: The pre-lithiation treatment conditions include: the current density applied to the pre-lithiation chamber by the pre-lithiation circuit is β, the pre-lithiation voltage is M, the pre-lithiation temperature is Tx, and at least one of the following conditions is satisfied: (1)20mA / cm 2 ≤β≤56mA / cm 2 ; (2) 2.6V≤M≤4.5V; (3) 110℃≤Tx≤130℃; The pre-lithium temperature Tx is the temperature of the pre-lithium platform.

15. The electrode pre-lithiation method according to claim 14, characterized in that: The pre-lithium treatment satisfies at least one of the following conditions: (1)35mA / cm 2 ≤β≤45mA / cm 2 ; (2) 3.3V≤M≤3.8V; (3) 110℃≤Tx≤120℃.

16. The electrode pre-lithiation method according to claim 12, characterized in that: The step of heating the molten salt and the lithium source to form a molten state comprises: The heating layer of the pre-lithium cavity heats the molten salt and the lithium source inside the pre-lithium cavity to a melting temperature Ty, so that the molten salt and the lithium source are in a molten state, 110°C≤Ty≤120°C.

17. The electrode pre-lithiation method according to claim 12, characterized in that: During the pre-lithiation process, the pressure applied by the electrolyte layer to the surface to be pre-lithiated is P, 0.1 Kg / cm 2 ≤P≤20 Kg / cm 2 .

18. The electrode pre-lithiation method according to claim 12, characterized in that: Before performing the pre-lithium treatment, the method further comprises: The active material coating of the electrode strip is transported to the preheating platform of the preheating unit by using the strip retracting mechanism, and after preheating, it is transported to the pre-lithium unit along a preset transport direction.

19. The electrode pre-lithiation method according to claim 18, characterized in that: The temperature Tc of the preheating treatment is: 105°C≤Tc≤125°C.

20. The electrode pre-lithiation method according to claim 12, characterized in that: The active material coatings coated at intervals on the electrode strip are transported to the pre-lithiation platform for single-side pre-lithiation, wherein the pre-lithiation cavity is provided on the same side of the pre-lithiation platform; There is at least one pre-lithium platform; There is at least one pre-lithium cavity.

21. The electrode pre-lithiation method according to claim 12, characterized in that: The active material coatings coated at intervals on the electrode strip are transported to the plurality of pre-lithiation platforms for double-sided pre-lithiation, wherein a portion of the pre-lithiation cavity is provided on one side of the plurality of pre-lithiation platforms and a portion of the pre-lithiation cavity is also provided on the other side.

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