A lithium-ion energy storage device with a pre-lithiation function

Abstract

The present invention provides a lithium-ion energy storage device with a pre-lithiation function, which includes a housing, an electrode core, and an electrolyte. The electrode core is made by stacking a positive electrode sheet, a separator, and a negative electrode sheet in sequence, and the outermost layer of the electrode core is wrapped by the separator; the electrode core is arranged inside the housing; the positive electrode sheet of the electrode core is connected to a positive electrode terminal, and the negative electrode sheet of the electrode core is connected to a negative electrode terminal; the housing includes a positive electrode cover plate, a negative electrode cover plate, a front housing, and a side housing. The front housing or the side housing is further provided with a protruding portion, and a lithium foil is arranged on the protruding portion. After the pre-lithiation process ends, the lithium foil disappears. The present invention makes the lithium foil contact the electrode core more closely, which is more convenient for the diffusion of lithium ions, thereby accelerating the pre-lithiation process and improving the pre-lithiation efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion energy storage devices, and particularly relates to a lithium-ion energy storage device with a pre-lithiation function. Background Art

[0002] Lithium-ion energy storage devices are lithium-ion capacitors, lithium-ion batteries, or lithium-ion battery capacitors with an internal parallel structure. For lithium-ion energy storage devices that require pre-lithiation, a soft packaging method is usually adopted. As disclosed in Chinese Patent CN104008893A, electrode plates and a separator are stacked or wound in the order of positive electrode / separator / negative electrode to form an electrode core, the electrode core is placed in an aluminum-plastic composite film housing, the top edge and the first side edge of the aluminum-plastic composite film housing are heat-sealed, the tabs of the positive and negative electrodes of the electrode core extend out of the aluminum-plastic composite film housing from the top edge, a metallic lithium electrode is placed in the aluminum-plastic composite film housing, the metallic lithium electrode is placed adjacent to the electrode core and separated by a separator, and the tab of the metallic lithium electrode extends out of the aluminum-plastic composite film housing from the second side edge; an excessive amount of electrolyte is injected into the aluminum-plastic composite film housing, and then the second side edge of the aluminum-plastic composite film housing is heat-sealed; in a constant current manner, with the negative electrode as the working electrode and the metallic lithium electrode as the counter electrode, pre-lithiation of the negative electrode is carried out; the metallic lithium electrode is taken out, the excess electrolyte is poured out, the second side edge of the aluminum-plastic composite film housing is vacuum heat-sealed, and finally a lithium-ion hybrid capacitor is obtained. However, this method is not applicable to lithium-ion energy storage devices with a steel shell. Summary of the Invention

[0003] In view of this, the present invention provides a lithium-ion energy storage device with a pre-lithiation function, which can realize pre-lithiation of a lithium-ion energy storage device with a steel shell, and the structure of the lithium-ion energy storage device can also make the lithium foil contact the electrode core more closely, which is more convenient for the diffusion of lithium ions, thereby accelerating the pre-lithiation process and improving the pre-lithiation efficiency.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A lithium-ion energy storage device with a pre-lithiation function includes a housing, an electrode core, and an electrolyte. The electrode core is made by stacking in the order of separator, negative electrode plate, separator, positive electrode plate, separator... negative electrode plate, separator, positive electrode plate, separator, negative electrode plate, separator, and the outermost layer of the electrode core is wrapped by a separator; the electrode core is arranged inside the housing; the positive electrode plate of the electrode core is connected to a positive electrode terminal, and the negative electrode plate of the electrode core is connected to a negative electrode terminal; the housing includes a positive electrode cover plate, a negative electrode cover plate, a front housing, and a side housing. The front housing or the side housing is further provided with a convex portion, and a lithium foil is arranged on the convex portion, and the lithium foil disappears after the pre-lithiation process ends.

[0006] Further, the housing and the convex portion are made of stainless steel, copper, or nickel.

[0007] Further, the raised portion is an elastomer.

[0008] Further, the thickness of the raised portion is 0.1 - 5 mm.

[0009] Further, the distance between the raised portion and the electrode core is less than or equal to 5 mm.

[0010] Further, the connection mode between the negative electrode sheet of the electrode core and the negative electrode terminal is ultrasonic welding, laser welding, riveting or resistance welding.

[0011] Further, the positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad. The negative electrode terminal is in contact with the negative electrode cover plate, and the two are electrically connected. The negative electrode cover plate is electrically connected to the front shell. The raised portion is located in the middle of the front shell, and the arrangement direction of the raised portion is parallel to that of the positive electrode sheet and the negative electrode sheet. The length of the raised portion is 0.5 - 1.0 times the length of the electrode core, and the width of the raised portion is 0.5 - 1.0 times the width of the electrode core. The length of the lithium foil provided on the raised portion is 0.5 - 1.0 times the length of the raised portion, the width of the lithium foil is 0.5 - 1.0 times the width of the raised portion, and the thickness of the lithium foil is 0.01 - 10 mm.

[0012] Further, the positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad, and the negative electrode terminal and the negative electrode cover plate are separated by a negative electrode terminal insulating pad. The raised portion is located in the middle of the front shell, and the arrangement direction of the raised portion is parallel to that of the positive electrode sheet and the negative electrode sheet. The length of the raised portion is 0.5 - 1.0 times the length of the electrode core, and the width of the raised portion is 0.5 - 1.0 times the width of the electrode core. The length of the lithium foil provided on the raised portion is 0.5 - 1.0 times the length of the raised portion, the width of the lithium foil is 0.5 - 1.0 times the width of the raised portion, and the thickness of the lithium foil is 0.01 - 10 mm.

[0013] Further, the positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad, and the negative electrode terminal and the negative electrode cover plate are separated by a negative electrode terminal insulating pad. A raised portion is provided on the side shell. The raised portion is located in the middle of the side shell, and the arrangement direction of the raised portion is perpendicular to that of the positive electrode sheet and the negative electrode sheet. The length of the raised portion is 0.5 - 1.0 times the length of the electrode core, and the width of the raised portion is 0.5 - 1.0 times the thickness of the electrode core. The length of the lithium foil provided on the raised portion is 0.5 - 1.0 times the length of the raised portion, the width of the lithium foil is 0.5 - 1.0 times the width of the raised portion, and the thickness of the lithium foil is 0.01 - 10 mm.

[0014] Further, a positive electrode pole column insulating pad is used to separate the positive electrode cover plate from the positive electrode pole column. The negative electrode pole column is in contact with the negative electrode cover plate, and the two are electrically connected. The negative electrode cover plate is electrically connected to the side shell. A convex portion is provided on the side shell. The convex portion is located in the middle of the side shell and is perpendicular to the arrangement direction of the positive electrode sheet and the negative electrode sheet. The length of the convex portion is 0.5 to 1.0 times the length of the electrode core, and the width of the convex portion is 0.5 to 1.0 times the thickness of the electrode core. The length of the lithium foil provided on the convex portion is 0.5 to 1.0 times the length of the convex portion, the width of the lithium foil is 0.5 to 1.0 times the width of the convex portion, and the thickness of the lithium foil is 0.01 to 10 mm.

[0015] Beneficial effects:

[0016] The technical solution proposed by the present invention can overcome the deficiency in the prior art that only soft-pack lithium-ion energy storage devices can be pre-lithiated while steel-shell lithium-ion energy storage devices cannot be pre-lithiated, and realize the pre-lithiation function of steel-shell lithium-ion energy storage devices. After adopting this technical solution, it is also convenient for lithium ions to diffuse along the side direction of the electrode core, thereby accelerating the pre-lithiation process and improving the pre-lithiation efficiency. After adopting the elastic convex portion, the lithium foil is in closer contact with the electrode core, the lithium ion diffusion path is shortened, and the pre-lithiation time is shortened. If a lithium foil is provided on the side shell, there is no need to use a current collector with a through hole, which can further reduce the production cost. Description of the drawings

[0017] Figure 1 is a side view of the structure of the lithium-ion energy storage device according to Embodiment 1 of the present invention;

[0018] Figure 2 is a front view of the structure of the lithium-ion energy storage device according to Embodiment 1 of the present invention, and the dotted box in the figure represents the convex portion;

[0019] Figure 3 is a side view of the structure of the lithium-ion energy storage device according to Embodiment 2 of the present invention;

[0020] Figure 4 is a front view of the structure of the lithium-ion energy storage device according to Embodiment 2 of the present invention, and the dotted box in the figure represents the convex portion;

[0021] Figure 5 is a side view of the structure of the lithium-ion energy storage device according to Embodiment 3 of the present invention;

[0022] Figure 6 is a front view of the structure of the lithium-ion energy storage device according to Embodiment 3 of the present invention;

[0023] Figure 7 is a side view of the structure of the lithium-ion energy storage device according to Embodiment 4 of the present invention;

[0024] Figure 8It is the front view of the structure of the lithium-ion energy storage device according to Embodiment 4 of the present invention.

[0025] Among them, 101 is the positive electrode terminal, and 102 is the negative electrode terminal; 201 is the positive electrode cover plate, 202 is the negative electrode cover plate, 203 is the front housing, and 204 is the side housing; 4 is the convex part, and 5 is the electrode core; 601 is the positive electrode terminal insulating pad, and 602 is the negative electrode terminal insulating pad; 7 is the explosion-proof port, 8 is the liquid injection port, and 9 is the lithium foil. Specific Embodiments

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be 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 the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] As Figure 1 , shown in FIGS. 3, 5, and 7, the lithium-ion energy storage device of the present invention includes a housing, an electrode core 5, and an electrolyte. The electrode core 5 is laminated in the order of separator, negative electrode sheet, separator, positive electrode sheet, separator... negative electrode sheet, separator, positive electrode sheet, separator, negative electrode sheet, separator. The outermost layer of the electrode core 5 is wrapped by a separator; the positive electrode sheet of the electrode core 5 is connected to the positive electrode terminal 101, and the negative electrode sheet of the electrode core 5 is connected to the negative electrode terminal 102; the housing includes a positive electrode cover plate 201, a negative electrode cover plate 202, a front housing 203, and a side housing 204. The front housing 203 or the side housing 204 is further provided with a convex part 4, and a lithium foil 9 is provided on the convex part 4. After the pre-lithiation process is completed, the lithium foil 9 disappears. The housing is made of a metal material, which is made of stainless steel or copper or nickel.

[0028] The lithium-ion energy storage device of the present invention can be a lithium-ion capacitor, a lithium-ion battery, or a lithium-ion battery capacitor with an internal parallel structure. Among them, the lithium-ion capacitor includes a capacitance-type positive electrode sheet and a battery-type negative electrode sheet, and its positive electrode sheet is mainly composed of a capacitance material, and the negative electrode sheet is mainly composed of a battery material. The lithium-ion battery capacitor has at least one electrode formed by a battery material and a capacitance material to form a so-called "internal parallel structure", that is, it can be equivalently regarded as a battery element and a capacitance element coexisting in the same energy storage device to form an internal parallel structure.

[0029] The negative electrode sheet of the lithium-ion energy storage device of the present invention includes a negative electrode current collector and a coating layer thereon. The negative electrode current collector is copper foil, perforated copper foil with through holes, copper foam or conductive carbon cloth; the thickness of the negative electrode current collector is 3 to 20 micrometers. The positive electrode sheet of the lithium-ion energy storage device of the present invention includes a positive electrode current collector and a coating layer thereon. The positive electrode current collector is aluminum foil, perforated aluminum foil with through holes, aluminum foam or conductive carbon cloth; the thickness of the positive electrode current collector is 5 to 20 micrometers. The porosity of the perforated copper foil is 2 to 50%. The composition of the coating layer is: the mass percentage of the binder is 3 to 30%, the mass percentage of the conductive agent is 5 to 15%, and the mass percentage of the negative electrode active material is 55 to 92%. The negative electrode sheet and the positive electrode sheet are obtained by mechanical mixing, coating and cutting. The method of the mechanical mixing includes but is not limited to ball milling the materials by a planetary ball mill, mixing the materials by a planetary mixer, mixing the materials by a high-speed homogenizer, mixing by extrusion using a screw machine, and a dry process of mixing and extrusion for film formation. The coating means uniformly coating the mixed slurry on the negative electrode and the positive electrode current collectors. The coating methods include but are not limited to transfer coating, extrusion coating, double-sided extrusion coating, electrode film pressing, etc.

[0030] The separator is a porous polymer insulating separator, and can be a cellulose separator, a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, a polyimide separator, etc. These separator materials can all be commercially available products.

[0031] The lithium-ion energy storage device of the present invention can adopt the method of electrochemical pre-lithiation, which can include the following 3 types: (1) Connect the metal lithium electrode to the negative electrode of the external power supply, connect the negative electrode sheet to the positive electrode of the external power supply, and discharge at a constant current until the total amount of lithium intercalation reaches the designed value, and the current is 0.01 to 0.5C; (2) Connect the metal lithium electrode to the positive electrode of the external power supply, connect the negative electrode sheet to the negative electrode of the external power supply, and charge at a constant current until the total amount of lithium intercalation reaches the designed value, and the current is 0.01 to 0.5C; (3) Connect the metal lithium electrode to the positive electrode of the external power supply, connect the negative electrode sheet to the negative electrode of the external power supply, and charge at a constant current of 0.01 to 0.5C to 0V; then, perform constant voltage charging at a constant voltage U0 until the total amount of lithium intercalation reaches the designed value, 0 < U0 ≤ 0.15V. Among them, the meaning of C, according to the "QB / T2502-2000 General Specification for Lithium-Ion Batteries", represents the capacity when the battery discharges at a 5-hour rate to the end voltage, that is: 1C represents the current value of 1 times the capacity, and 5C represents the current value of 5 times the capacity.

[0032] The lithium-ion energy storage device of the present invention can also adopt the method of short-circuit pre-lithiation. Stack the positive electrode, separator, and negative electrode, set separators on the uppermost part and the lowermost part respectively, fix the four sides with tape, and weld the terminal welding parts of the positive electrode current collector and the negative electrode current collector to the aluminum positive terminal and the copper negative terminal respectively by ultrasonic welding to obtain an electrode stack unit. Set a lithium electrode on the upper and lower parts of the electrode stack unit respectively, and weld the terminal welding part of the lithium electrode current collector to the negative terminal part by resistance welding. After injecting the electrolyte and sealing, leave it for 20 days, disassemble the battery, and find that the metallic lithium is completely consumed, thus judging that the pre-lithiation process is completed.

[0033] In the technical solution provided by the present invention, the electrode core is laminated in the order of separator, negative electrode sheet, separator, positive electrode sheet, separator... negative electrode sheet, separator, positive electrode sheet, separator, negative electrode sheet, separator. Figure 1 ,3,5,7 The dotted line direction indicates the arrangement direction of the positive electrode sheet, separator, and negative electrode sheet. The positive electrode sheet of the electrode core is connected to the positive electrode column, and the negative electrode sheet of the electrode core is connected to the negative electrode column. The connection method is ultrasonic welding, laser welding, riveting or resistance welding.

[0034] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0035] Example 1

[0036] As Figure 1 , Figure 2 shown, in Example 1, a positive electrode column insulating pad 601 is used to separate the positive electrode cover plate 201 from the positive electrode column 101. The negative electrode column 102 is in contact with the negative electrode cover plate 202, and the two are electrically connected; the negative electrode cover plate 202 is electrically connected to the front housing 203.

[0037] A convex portion 4 is provided on the front housing 203. The convex portion 4 is made of stainless steel, copper or nickel. The convex portion 4 is located in the middle of the front housing 203, and the convex portion 4 is parallel to the arrangement direction of the positive electrode sheet and the negative electrode sheet. The length of the convex portion 4 is 0.5 to 1.0 times the length of the electrode core 5, and the width of the convex portion 4 is 0.5 to 1.0 times the width of the electrode core 5. The thickness of the convex portion 4 is 0.1 to 5 mm. The distance between the convex portion 4 and the electrode core 5 is less than or equal to 5 mm. The positive electrode cover plate 201, the negative electrode cover plate 202, the front housing 203, and the side housing 204 can be integrally designed or assembled in an argon atmosphere when the electrode core 5 is placed. An explosion-proof port 7 is provided on the positive electrode cover plate. When the internal pressure of the lithium-ion energy storage device housing is greater than the design pressure, the explosion-proof port 7 opens to release the gas in the housing.

[0038] The preparation method of the lithium-ion energy storage device in this embodiment is as follows: Fix a lithium foil 9 with a thickness of 0.01 - 10 mm on the protrusion 4. Assemble the positive electrode cover plate 201, negative electrode cover plate 202, front shell 203, and side shell 204 into a shell. Place the electrode core 5 into the shell to assemble the lithium-ion energy storage device. After injecting electrolyte from the liquid injection port 8, seal the liquid injection port 8. At this time, there is an electrical connection between the protrusion 4, the front shell 203, the negative electrode post 102, and the negative electrode cover plate 202. The lithium foil dissolves and lithium ions are embedded into the negative electrode sheet. Place the lithium-ion energy storage device until the voltage between the positive electrode post 101 and the negative electrode post 102 no longer changes. At this time, the lithium foil is completely dissolved, and the pre-lithiation process is completed. After performing 1 - 5 charge and discharge cycles on the lithium-ion energy storage device, the formation of the lithium-ion energy storage device is completed. Vacuum pump out the generated gas and finally seal the liquid injection port 8 to obtain the lithium-ion energy storage device. The protrusion 4 can also be made of an elastomer, which is a material or structure with elasticity. Using Embodiment 1 can achieve an integrated pre-lithiation function without having to disassemble the shell to remove the metallic lithium electrode again; by adjusting the gap between the protrusion 4 and the electrode core 5 and the thickness of the protrusion, it is possible to easily adjust the fitting degree between the metallic lithium electrode and the electrode core 5, thereby adjusting the transmission distance of lithium ions and shortening the pre-lithiation time.

[0039] Embodiment 2

[0040] As Figure 3 , Figure 4 shown, a positive electrode post insulating pad 601 is used to separate the positive electrode cover plate 201 and the positive electrode post 101, and a negative electrode post insulating pad 602 is used to separate the negative electrode post 102 and the negative electrode cover plate 202.

[0041] A protrusion 4 is provided on the front shell 203. The protrusion 4 is made of stainless steel, copper, or nickel. The protrusion 4 is located in the middle of the front shell 203, and the arrangement direction of the protrusion 4 is parallel to that of the positive electrode sheet and the negative electrode sheet. The length of the protrusion 4 is 0.5 - 1.0 times the length of the electrode core 5, and the width of the protrusion 4 is 0.5 - 1.0 times the width of the electrode core 5. The distance between the protrusion 4 and the electrode core 5 is less than or equal to 5 mm. An explosion-proof port 7 is provided on the positive electrode cover plate. When the internal pressure of the lithium-ion energy storage device shell is greater than the design pressure, the explosion-proof port 7 opens to release the gas inside the shell.

[0042] Preparation method of the lithium-ion energy storage device in this embodiment: Fix the lithium foil 9 on the convex part 4, where the thickness of the lithium foil 9 is 0.01 - 10 mm. Assemble the positive electrode cover plate 201, negative electrode cover plate 202, front shell 203, and side shell 204 into a shell, put the electrode core 5 into the shell to assemble a lithium-ion energy storage device. After injecting the electrolyte through the liquid injection port 8, seal the liquid injection port 8. At this time, there is no electrical connection between the convex part 4, the front shell 203, the negative electrode post 102, and the negative electrode cover plate 202. Connect the negative electrode post 102 of the lithium-ion energy storage device to the positive electrode of the Neware charge and discharge instrument, and make the front shell 203 contact the negative electrode post 102 of the Neware charge and discharge instrument. Use the method of electrochemical discharge for pre-lithiation, causing the dissolution of the lithium foil and the embedding of lithium ions into the negative electrode sheet.

[0043] Or after using the method of electrochemical discharge for partial pre-lithiation, connect the negative electrode post 102 to the front shell 203, and complete the remaining part of the pre-lithiation by short-circuiting. After performing 1 - 5 charge and discharge cycles on the lithium-ion energy storage device, complete the formation of the lithium-ion energy storage device, evacuate the generated gas under vacuum, and finally seal the liquid injection port to obtain the lithium-ion energy storage device.

[0044] Example 3

[0045] As Figure 5 , Figure 6 shown, the positive electrode post insulating pad 601 is used to separate the positive electrode cover plate 201 and the positive electrode post 101, and the negative electrode post insulating pad 602 is used to separate the negative electrode post 102 and the negative electrode cover plate 202.

[0046] A convex part 4 is provided on the side shell 204. The convex part 4 is made of stainless steel, copper, or nickel. The convex part 4 is located in the middle of the side shell 204, and the arrangement direction of the convex part 4 is perpendicular to that of the positive electrode sheet and the negative electrode sheet. The length of the convex part 4 is 0.5 - 1.0 times the length of the electrode core 5, and the width of the convex part 4 is 0.5 - 1.0 times the thickness of the electrode core 5. The distance between the convex part 4 and the electrode core 5 is less than or equal to 5 mm. An explosion-proof port 7 is provided on the positive electrode cover plate. When the internal pressure of the lithium-ion energy storage device shell is greater than the design pressure, the explosion-proof port 7 opens to release the gas in the shell.

[0047] Preparation method of the lithium-ion energy storage device in this embodiment: Fix the lithium foil 9 on the convex part 4, the thickness of the lithium foil 9 is 0.01 - 10 mm. Assemble the positive electrode cover plate 201, the negative electrode cover plate 202, the front shell 203, and the side shell 204 into a shell, put the electrode core 5 into the shell to assemble a lithium-ion energy storage device. After injecting the electrolyte from the liquid injection port 8, seal the liquid injection port 8. Connect the negative electrode terminal 102 of the lithium-ion energy storage device to the positive electrode of the Neware charge and discharge instrument, and make the front shell 203 contact with the negative electrode terminal 102 of the Neware charge and discharge instrument. Use the method of electrochemical discharge for pre-lithiation. At this time, there is no electrical connection between the convex part 4, the front shell 203 and the negative electrode terminal 102 and the negative electrode cover plate 202. After performing 1 - 5 charge and discharge cycles on the lithium-ion energy storage device, the formation of the lithium-ion energy storage device is completed. Vacuum pump out the generated gas, and finally seal the liquid injection port 8 to obtain the lithium-ion energy storage device. Since the convex part 4 is perpendicular to the arrangement directions of the positive electrode sheet and the negative electrode sheet, during the pre-lithiation process, lithium ions diffuse into the electrode core from the side of the electrode core. For the electrode sheets with a two-dimensional structure, the diffusion rate from the side is faster, and the electrochemical pre-lithiation time is shortened from two days to 2 - 8 hours.

[0048] For the structure where the convex part 4 is parallel to the arrangement directions of the positive electrode sheet and the negative electrode sheet, since lithium ions need to pass through the stacked negative electrode sheets and positive electrode sheets during pre-lithiation, the negative electrode sheet and the positive electrode sheet need to use current collectors with a through-hole structure. The cost of the current collector with a through-hole structure is 50% - 200% higher than that of the current collector without a through-hole structure, which will increase the cost. For the structure where the convex part 4 is perpendicular to the arrangement directions of the positive electrode sheet and the negative electrode sheet, since lithium ions do not need to pass through the stacked negative electrode sheets and positive electrode sheets during pre-lithiation, the negative electrode sheet and the positive electrode sheet do not need to use current collectors with a through-hole structure, which will greatly reduce the cost of the current collector.

[0049] For the structure where the convex part 4 is parallel to the arrangement directions of the positive electrode sheet and the negative electrode sheet, since lithium ions need to pass through the stacked negative electrode sheets and positive electrode sheets during pre-lithiation, the negative electrode sheet and the positive electrode sheet need to use current collectors with a through-hole structure. During the process of injecting the electrolyte and electrochemical pre-lithiation, and the potential of lithium ions drops by V when passing through each negative electrode sheet, and the potential of lithium ions drops by V when passing through each positive electrode sheet. Therefore, there is a certain limit to the thickness of the electrode core. When the thickness of the electrode core exceeds a certain thickness value, large electrochemical polarization will occur, or the pre-lithiation time will be too long due to too small pre-lithiation current. When using the structure where the convex part 4 is perpendicular to the arrangement directions of the positive electrode sheet and the negative electrode sheet, there is no limit to the thickness of the electrode core.

[0050] The cost of the current collector with a through-hole structure is 50% to 200% higher than that of the current collector without a through-hole structure, which will lead to an increase in cost. For the structure where the protruding part 4 is perpendicular to the arrangement directions of the positive electrode sheet and the negative electrode sheet, since lithium ions do not need to pass through the stacked negative electrode sheet and positive electrode sheet during pre-lithiation, the current collectors of the negative electrode sheet and the positive electrode sheet do not need to adopt a through-hole structure, which will lead to a significant reduction in the cost of the current collector.

[0051] After pre-lithiation of 30% to 90% is carried out by using the method of electrochemical discharge, the negative electrode terminal 102 can be connected to the front shell 203, and the remaining part of the pre-lithiation can be completed by the method of short circuit, so as to improve the use efficiency of the Neware charge and discharge instrument, save electric energy and production costs.

[0052] Embodiment 4

[0053] As Figure 7 , Figure 8 As shown in the figure, the positive electrode cover plate 201 and the positive electrode terminal 101 are separated by the positive electrode terminal insulating pad 601. The negative electrode terminal 102 is in contact with the negative electrode cover plate 202, and the two are electrically connected. The negative electrode cover plate 202 is electrically connected to the side shell 204.

[0054] A protruding part 4 is arranged on the side shell 204. The protruding part 4 is made of stainless steel, copper or nickel. The protruding part 4 is located in the middle of the side shell 204, and the protruding part 4 is perpendicular to the arrangement directions of the positive electrode sheet and the negative electrode sheet. The length of the protruding part 4 is 0.5 to 1.0 times the length of the electrode core 5, and the width of the protruding part 4 is 0.5 to 1.0 times the thickness of the electrode core 5. The distance between the protruding part 4 and the electrode core 5 is less than or equal to 5 mm. An explosion-proof port 7 is arranged on the positive electrode cover plate. When the internal pressure of the lithium-ion energy storage device shell is greater than the designed pressure, the explosion-proof port 7 opens to release the gas in the shell.

[0055] The preparation method of the lithium-ion energy storage device in this embodiment: A lithium foil 9 with a thickness of 0.01 to 10 mm is fixed on the protruding part 4. The positive electrode cover plate 201, the negative electrode cover plate 202, the front shell 203 and the side shell 204 are assembled into a shell, the electrode core 5 is placed in the shell and assembled into a lithium-ion energy storage device. After injecting electrolyte from the liquid injection port 8, the liquid injection port 8 is sealed. At this time, the protruding part 4, the front shell 203 are electrically connected to the negative electrode terminal 102 and the negative electrode cover plate 202, and the dissolution of the lithium foil and the embedding of lithium ions into the negative electrode sheet occur. The lithium-ion energy storage device is placed until the voltage between the positive electrode terminal 101 and the negative electrode terminal 102 no longer changes. At this time, the lithium foil is completely dissolved, and the pre-lithiation process is completed. After the lithium-ion energy storage device is charged and discharged 1 to 5 times, the formation of the lithium-ion energy storage device is completed, the gas generated by vacuum pumping is removed, and the liquid injection port is finally sealed to obtain the lithium-ion energy storage device.

[0056] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lithium-ion energy storage device with a pre-lithiation function, characterized in that: The lithium-ion energy storage device is a steel-shell lithium-ion energy storage device, and pre-lithiation is performed on it. The lithium-ion energy storage device includes a housing, an electrode core, and an electrolyte. The electrode core is laminated in the order of separator, negative electrode sheet, separator, positive electrode sheet, separator... negative electrode sheet, separator, positive electrode sheet, separator, negative electrode sheet, separator. The outermost layer of the electrode core is wrapped by a separator; the electrode core is arranged inside the housing; the positive electrode sheet of the electrode core is connected to the positive electrode terminal, and the negative electrode sheet of the electrode core is connected to the negative electrode terminal; the housing includes a positive electrode cover plate, a negative electrode cover plate, a front housing, and a side housing. The side housing is provided with a protrusion, and a lithium foil is arranged on the protrusion. After the pre-lithiation process ends, the lithium foil disappears; The distance between the protrusion and the electrode core is less than or equal to 5 mm; The arrangement direction of the protrusion is perpendicular to that of the positive electrode sheet and the negative electrode sheet.

2. The lithium-ion energy storage device according to claim 1, wherein: The housing and the protrusion are made of stainless steel, copper or nickel.

3. The lithium-ion energy storage device according to claim 1, wherein: The protrusion is an elastomer.

4. The lithium-ion energy storage device according to claim 1, characterized in that: The thickness of the protrusion is 0.1 - 5 mm.

5. The lithium-ion energy storage device according to claim 1, wherein: The connection method between the negative electrode sheet of the electrode core and the negative electrode terminal is ultrasonic welding, laser welding, riveting or resistance welding connection.

6. The lithium-ion energy storage device according to any one of claims 1 to 5, characterized in that: The positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad. The negative electrode terminal is in contact with and electrically connected to the negative electrode cover plate, and the negative electrode cover plate is electrically connected to the front housing; the protrusion is located in the middle of the front housing, and the arrangement direction of the protrusion is parallel to that of the positive electrode sheet and the negative electrode sheet. The length of the protrusion is 0.5 - 1.0 times the length of the electrode core, and the width of the protrusion is 0.5 - 1.0 times the width of the electrode core; the length of the lithium foil arranged on the protrusion is 0.5 - 1.0 times the length of the protrusion, the width of the lithium foil is 0.5 - 1.0 times the width of the protrusion, and the thickness of the lithium foil is 0.01 - 10 mm.

7. The lithium-ion energy storage device according to any one of claims 1 to 5, characterized in that: The positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad, and the negative electrode terminal and the negative electrode cover plate are separated by a negative electrode terminal insulating pad; the protrusion is located in the middle of the front housing, and the arrangement direction of the protrusion is parallel to that of the positive electrode sheet and the negative electrode sheet. The length of the protrusion is 0.5 - 1.0 times the length of the electrode core, and the width of the protrusion is 0.5 - 1.0 times the width of the electrode core; the length of the lithium foil arranged on the protrusion is 0.5 - 1.0 times the length of the protrusion, the width of the lithium foil is 0.5 - 1.0 times the width of the protrusion, and the thickness of the lithium foil is 0.01 - 10 mm.

8. The lithium-ion energy storage device according to any one of claims 1 to 5, characterized in that: The positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad, and the negative electrode terminal and the negative electrode cover plate are separated by a negative electrode terminal insulating pad; a protrusion is arranged on the side housing. The protrusion is located in the middle of the side housing, and the arrangement direction of the protrusion is perpendicular to that of the positive electrode sheet and the negative electrode sheet. The length of the protrusion is 0.5 - 1.0 times the length of the electrode core, and the width of the protrusion is 0.5 - 1.0 times the thickness of the electrode core; the length of the lithium foil arranged on the protrusion is 0.5 - 1.0 times the length of the protrusion, the width of the lithium foil is 0.5 - 1.0 times the width of the protrusion, and the thickness of the lithium foil is 0.01 - 10 mm.

9. The lithium-ion energy storage device according to any one of claims 1 to 5, characterized in that: The positive electrode cover plate and the positive electrode terminal are separated by a positive electrode terminal insulating pad. The negative electrode terminal is in contact with and electrically connected to the negative electrode cover plate, and the negative electrode cover plate is electrically connected to the side shell. A protrusion is provided on the side shell. The protrusion is located in the middle of the side shell and is perpendicular to the arrangement direction of the positive electrode sheet and the negative electrode sheet. The length of the protrusion is 0.5 to 1.0 times the length of the electrode core, and the width of the protrusion is 0.5 to 1.0 times the thickness of the electrode core. The length of the lithium foil provided on the protrusion is 0.5 to 1.0 times the length of the protrusion, the width of the lithium foil is 0.5 to 1.0 times the width of the protrusion, and the thickness of the lithium foil is 0.01 to 10 mm.

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