Lithium ion battery and liquid injection method thereof

Abstract

According to the lithium ion battery and the liquid injection method thereof provided by the invention, the electrolyte can flow through the first through hole, the second through hole and the third through hole and is injected into the shell to infiltrate the battery cell, and the second through hole is formed in the positive pole, so that opening formation can be realized after one-time liquid injection; after the opening is formed, the first through hole, the second through hole and the third through hole are used for secondary liquid injection, and the sealing bead is welded in the second through hole of the positive pole post to seal the second through hole after the secondary liquid injection, so that the battery structure can change the traditional primary liquid injection, the secondary liquid injection is realized, the liquid injection efficiency is greatly improved, and the service life of the battery is prolonged. The secondary liquid injection can enable the pole piece to be better infiltrated by the electrolyte, the service life of the battery cell is prolonged, the battery structure can change the traditional closed formation, realize open formation and discharge gas generated during formation into the battery cell, space is provided for secondary liquid injection, internal pressure is reduced, the safety of the product is improved, and the service life of the product is prolonged.

Description

[Technical field]

[0001] The present invention relates to the technical field of batteries, and in particular to a lithium ion battery and a liquid injection method thereof. [Background technology]

[0002] Lithium-ion batteries need to be injected with electrolyte during the preparation process. The existing process usually adopts one-time injection, and after injection, the cylindrical battery is sealed and packaged for formation, that is, closed-mouth formation. The existing battery structure only supports the process of one-time injection and closed-mouth formation. However, one-time injection cannot guarantee the electrode is infiltrated by the electrolyte, and closed-mouth formation prevents the gas in the formation stage from being discharged.

[0003] In view of this, it is necessary to provide a new type of lithium ion battery and its injection method to overcome the above defects. [Summary of the invention]

[0004] The object of the present invention is to provide a lithium ion battery and a preparation method thereof to solve the above technical problems.

[0005] In order to achieve the above-mentioned purpose, in the first aspect, the present invention provides a lithium-ion battery, comprising a shell with an opening at one end, a battery cell accommodated in the shell, a negative current collector and a positive current collector assembly; the negative current collector is welded to the negative end surface of the battery cell, and the positive current collector assembly is arranged at one end of the shell opening; the positive current collector assembly comprises a positive current collector, a positive electrode column, an aluminum plate and a sealing bead; the positive current collector comprises a first surface and a second surface opposite to the first surface, the first surface of the positive current collector is welded to the positive end surface of the battery cell, and one end of the positive electrode column is welded to the positive current collector. on the second surface of the shell, the other end of the positive electrode column is welded to the aluminum plate; a first through hole penetrating the first surface and the second surface is opened at the center of the positive collecting disk, a second through hole penetrating the first surface and the second surface is opened at the center of the positive electrode column, and a third through hole penetrating the first surface and the second surface is opened at the center of the aluminum plate, and the first through hole, the second through hole and the third through hole are positioned relatively; the first through hole, the second through hole and the third through hole are used to inject electrolyte into the shell, the sealing bead is welded in the second through hole of the positive electrode column and the sealing bead is used to seal the second through hole after a vacuum injection, an opening formation and a secondary vacuum injection.

[0006] In a preferred embodiment, an injection hole is provided at one end of the positive electrode column close to the aluminum plate, the injection hole is connected to the second through hole, and the diameter of the injection hole gradually decreases in a direction away from the aluminum plate.

[0007] In a preferred embodiment, a welding ring groove is formed at one end of the positive electrode column close to the aluminum plate, the welding ring groove surrounds the injection hole, and the aluminum plate is welded in the welding ring groove.

[0008] In a preferred embodiment, a ring-shaped explosion-proof scoreline is provided on the surface of the aluminum plate close to the positive electrode column, and the explosion-proof scoreline surrounds the third through hole of the aluminum plate.

[0009] In a second aspect, the present invention provides a method for injecting liquid into a lithium-ion battery, wherein the lithium-ion battery comprises a shell with an opening at one end, a battery cell contained in the shell, a negative current collector and a positive current collector assembly; the negative current collector is welded to the negative end surface of the battery cell, and the positive current collector assembly is arranged at one end of the shell opening;

[0010] The positive current collector assembly comprises a positive current collector, a positive electrode column, an aluminum plate and a sealing bead; the positive current collector comprises a first surface and a second surface opposite to the first surface, the first surface of the positive current collector is welded to the positive terminal surface of the battery cell, one end of the positive electrode column is welded to the second surface of the positive current collector, and the other end of the positive electrode column is welded to the aluminum plate; a first through hole penetrating the first surface and the second surface is provided at the center of the positive current collector, a second through hole penetrating the positive electrode column is provided at the center, and a third through hole penetrating the positive electrode column is provided at the center, and the first through hole, the second through hole and the third through hole are positioned relatively to each other;

[0011] The liquid injection method comprises the following steps:

[0012] Primary vacuum injection: injecting electrolyte into the shell for the first time, the electrolyte flows through the third through hole, the second through hole, the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell;

[0013] Opening formation: Forming is performed when the second through hole is not sealed;

[0014] Secondary vacuum injection: injecting electrolyte into the shell for the second time, the electrolyte flows through the third through hole, the second through hole, the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell;

[0015] Sealing: welding a sealing bead into the second through hole of the positive electrode column to seal the second through hole.

[0016] In a preferred embodiment, the vacuum injection further comprises the following steps:

[0017] Inserting a rubber plug into the second through hole for temporary sealing;

[0018] The temporarily sealed lithium-ion battery is placed in a high temperature static state, the high temperature static state environment is -45℃ dew point, the temperature is 45±2℃, and the high temperature static state time is 48h;

[0019] After high temperature quiescence, the rubber plug is pulled out and then the opening is formed.

[0020] In a preferred embodiment, the injection volume of the first vacuum injection is 85-90% of the total injection volume, and the injection time of the first vacuum injection is 50 minutes; the injection volume of the second vacuum injection is 10-15% of the total injection volume, and the injection time of the second vacuum injection is 30 minutes.

[0021] In a preferred embodiment, the environmental parameters of the environment in which the primary vacuum injection and the secondary vacuum injection are located are: internal microenvironment -45°C dew point, temperature 23+3°C, external environment -30°C dew point, temperature 23±3°C.

[0022] In a preferred embodiment, the step of forming the opening comprises:

[0023] After standing for 1 minute, charge at 0.05C constant current for 120 minutes, and then charge at 0.15C constant current for 90 minutes to 30% SOC;

[0024] The first OCV test is performed after the opening is formed.

[0025] In a preferred embodiment, the lithium-ion batteries are sealed with sealing beads, cleaned, glued, welded, oiled, assembled, kept at high temperature for 48 hours, subjected to a second OCV test, recharged, kept at high temperature for 7 days, kept at room temperature for 12 hours, and subjected to a third OCV test before being divided, tested, and shipped.

[0026] Compared with the prior art, the lithium-ion battery and the preparation method thereof provided by the present invention have a first surface of the positive current collector and a positive terminal surface of the battery cell welded to each other, one end of the positive electrode column is welded to the second surface of the positive current collector, and the other end of the positive electrode column is welded to the aluminum plate. A first through hole penetrating the first surface and the second surface is provided at the center of the positive current collector, a second through hole penetrating the center of the positive electrode column is provided, and a third through hole penetrating the center of the aluminum plate is provided, and the first through hole, the second through hole, and the third through hole are positioned relatively to each other, and the electrolyte can flow through the first through hole, the second through hole, and the third through hole and be injected into the shell to infiltrate the battery cell. Since the positive electrode column is provided with a second through hole, After the first injection, open formation can be achieved. After the open formation, the first through hole, the second through hole and the third through hole are used for secondary injection. After the secondary injection, the sealing bead is welded in the second through hole of the positive electrode column to seal the second through hole. This battery structure can change the traditional primary injection and achieve secondary injection, greatly improving the injection efficiency. The secondary injection can make the electrode better infiltrated with electrolyte and increase the service life of the battery cell. This battery structure can change the traditional closed formation and achieve open formation, and the gas generated during the formation is discharged from the inside of the battery cell, which provides space for the secondary injection and reduces the internal pressure, thereby increasing the safety and life of the product.

Brief Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A structural diagram of a lithium-ion battery provided by the present invention;

[0029] Figure 2 Another structural diagram of the lithium-ion battery provided by the present invention;

[0030] Figure 3 for Figure 2 The enlarged view of point A in the middle;

[0031] Figure 4 An exploded structural diagram of the lithium-ion battery provided by the present invention;

[0032] Figure 5 A structural diagram of a positive current collecting disk in a lithium-ion battery provided by the present invention;

[0033] Figure 6 A structural diagram of a positive electrode column in a lithium-ion battery provided by the present invention;

[0034] Figure 7 A structural diagram of an aluminum plate in a lithium-ion battery provided by the present invention;

[0035] Figure 8 for Figure 7 Middle AA section view;

[0036] Fig. 9 A structural diagram of a sealing ring in a lithium-ion battery provided by the present invention;

[0037] Fig.10 A flow chart of a lithium-ion battery injection method provided by one embodiment of the present invention;

[0038] Fig.11 A flow chart of a lithium-ion battery injection method provided in yet another embodiment of the present invention. [Specific implementation method]

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0040] See also Figure 1 , which is a structural diagram of the lithium-ion battery 100 provided by the present invention. The lithium-ion battery 100 provided by the present invention can change the traditional one-time liquid injection to realize the secondary liquid injection, greatly improving the liquid injection efficiency, and the battery structure can change the traditional closed-mouth formation to realize the open-mouth formation, and discharge the gas generated during the formation into the battery cell.

[0041] See also Figure 2 The lithium-ion battery 100 includes a housing 10 with an opening at one end, a battery cell 20 contained in the housing 10, a negative current collector 30, and a positive current collector assembly 40. The negative current collector 30 is welded to the negative end surface of the battery cell 20, and the positive current collector assembly 40 is disposed at one end of the housing 10.

[0042] Please also read Figure 3 and Figure 4 The positive current collecting disc assembly 40 includes a positive current collecting disc 41, a positive electrode column 42, an aluminum plate 43 and a sealing bead 44. The positive current collecting disc 41 includes a first surface 411 and a second surface 412 opposite to the first surface 411. The first surface 411 of the positive current collecting disc 41 is welded to the positive terminal surface 202 of the battery cell 20, one end of the positive electrode column 42 is welded to the second surface 412 of the positive current collecting disc 41, and the other end of the positive electrode column 42 is welded to the aluminum plate 43.

[0043] Furthermore, a first through hole 401 penetrating the first surface 411 and the second surface 422 is provided at the center of the positive current collecting disk 41, a second through hole 421 penetrating the positive electrode column 42 is provided at the center of the positive electrode column 42, and a third through hole 431 penetrating the positive electrode column 42 is provided at the center of the aluminum plate 43, and the first through hole 401, the second through hole 421, and the third through hole 431 are positioned relative to each other. The first through hole 401, the second through hole 421, and the third through hole 431 are used to inject electrolyte into the housing 10, and the sealing bead 44 is welded in the second through hole 421 of the positive electrode column 42, and the sealing bead 44 is used to seal the second through hole 421 after the first vacuum injection, the opening formation, and the second vacuum injection.

[0044] In the lithium-ion battery 100 provided by the present invention, the first surface 411 of the positive current collecting disk 41 is welded to the positive terminal surface 202 of the battery cell 20, one end of the positive electrode column 42 is welded to the second surface 412 of the positive current collecting disk 41, and the other end of the positive electrode column 42 is welded to the aluminum plate 43. A through hole 401 penetrating the first surface 411 and the second surface 422 is provided at the center of the positive current collecting disk 41, a second through hole 421 penetrating the center of the positive electrode column 42 is provided, and a third through hole 431 penetrating the center of the aluminum plate 43 is provided, and the first through hole 401, the second through hole 421, and the third through hole 431 are positioned relative to each other, and the electrolyte can flow through the first through hole 401, the second through hole 421, and the third through hole 431 and be injected into the shell 10 to infiltrate the battery cell 20. Since the positive electrode column 42 is provided with a second through hole 421, open formation can be achieved after the first injection. After the open formation, the first through hole 401, the second through hole 421 and the third through hole 431 are used for secondary injection. After the secondary injection, the sealing bead 44 is welded in the second through hole 421 of the positive electrode column 42 to seal the second through hole 421. This battery structure can change the traditional primary injection and achieve secondary injection, greatly improving the injection efficiency. The secondary injection can make the electrode better infiltrated with the electrolyte and increase the service life of the battery cell. This battery structure can change the traditional closed-end formation and achieve open formation, and the gas generated during the formation is discharged from the battery cell, which provides space for the secondary injection and reduces the internal pressure, thereby increasing the safety and life of the product.

[0045] The housing 10 is a cylindrical steel shell, and the housing 10 has a receiving space. The housing 10 includes a bottom surface and an outer peripheral surface connected to the bottom surface, and the bottom surface and the outer peripheral surface enclose a receiving space, and the battery cell 20 is received in the receiving space. Specifically, the housing 10 is open at one end away from the bottom surface, the positive collector plate assembly is arranged at the open end of the housing 10, and the negative collector plate 30 is arranged on the bottom surface.

[0046] The battery cell 20 is cylindrical and can be specifically formed by winding electrode sheets. The battery cell 20 includes a positive terminal face and a negative terminal face opposite to the positive terminal face. The negative terminal face of the battery cell is welded to the negative current collecting plate 30 to lead out the negative electrode of the lithium-ion battery, and the positive terminal face of the battery cell is welded to the positive current collecting plate assembly 40 to lead out the positive electrode of the lithium-ion battery.

[0047] Specifically, the negative collector disc 30 is a circular sheet structure, and the negative collector disc 30 is used to conduct the negative end surface of the battery cell (for example, the negative ear on the negative end surface) and the shell 10. A welding boss is provided at the center of the negative collector disc, and the welding boss is used to be welded and fixed to the shell 10. The negative collector disc 30 is provided with a plurality of reinforcing ribs, which are arranged along the radial direction of the negative collector disc, and the plurality of reinforcing ribs are arranged around the welding boss. The reinforcing ribs can strengthen the overall strength of the negative collector disc to prevent the collector disc from being squeezed and deformed by external force when the collector disc is grabbed during the production process.

[0048] In this embodiment, there are four reinforcing ribs, which are symmetrically arranged. Laser slotting lines are arranged on both sides of the reinforcing ribs. The laser slotting lines create a pullable space inside and outside the slotting lines. When the battery cell is subjected to a certain vibration during actual use, the welding position will not become unsoldered and fail. At the same time, the reinforcement ribs can increase the elastic coefficient inside and outside the slotting lines. Several positioning grooves are also provided on the edge of the negative collector plate 30. The positioning grooves facilitate the positioning of incoming materials and facilitate automated production. The number of positioning grooves is specifically four, and the shape of the positioning grooves is specifically semicircular.

[0049] See also Figure 5 In some embodiments, the positive current collector 41 is a circular sheet structure, and the positive current collector 41 is used to conduct the positive terminal surface of the battery cell (for example, the positive ear on the positive terminal surface) and the positive electrode column 42. Specifically, the first through hole 401 is located at the center of the positive current collector 41, and the second surface of the positive current collector 41 includes a welding area 410 surrounding the first through hole 401, and the positive electrode column 42 is welded in the welding area. A plurality of reinforcing ribs 413 are arranged on the second surface 412 of the positive current collector 41, and the plurality of reinforcing ribs are arranged along the radial direction of the positive current collector, and one end of the plurality of reinforcing ribs close to the center of the positive current collector 41 abuts against the positive electrode column 42. The reinforcing ribs 413 are arranged at a position outside the welding area, and the reinforcing ribs 413 are conducive to positioning the positive electrode column during welding, and can also strengthen the overall strength of the positive current collector to prevent the collector from being squeezed and deformed by external force when the collector is grabbed during the production process.

[0050] In this embodiment, there are four reinforcing ribs 413, which are symmetrically arranged. Laser slot lines 414 are arranged on both sides of the reinforcing ribs 413. The laser slot lines 414 create a pullable space inside and outside the slot lines. When the battery cell is subjected to a certain vibration during actual use, the welding position will not become unsoldered and fail. At the same time, the reinforcing ribs 413 can increase the elastic coefficient inside and outside the slot lines. Several positioning grooves 415 are also arranged on the edge of the positive collector 41. The positioning grooves 415 facilitate the positioning of incoming materials and facilitate automated production. The number of positioning grooves 415 is specifically four, and the shape of the positioning grooves 415 is specifically semicircular.

[0051] See also Figure 6 The positive electrode column 42 is roughly cylindrical, and is provided with a second through hole 421 that penetrates the positive electrode column 42. The second through hole 421 is located at the center of the positive electrode column. The positive electrode column 42 is located between the positive current collecting disk 41 and the aluminum plate 43. The positive electrode column 42 is used to conduct the positive current collecting disk 41 and the aluminum plate 43.

[0052] In some embodiments, an injection hole 422 is opened at one end of the positive electrode 42 close to the aluminum plate 43, and the injection hole 422 is connected to the second through hole 421. The diameter of the injection hole 422 gradually decreases in the direction away from the aluminum plate 43, that is, the injection hole 422 is a conical injection hole, which is convenient for the automatic positioning of the equipment's injection nozzle and for the insertion and removal of nails in the injection and formation processes. The injection hole 422 and the second through hole 421 also play the role of exhaust after formation.

[0053] Furthermore, a welding annular groove 423 is provided at one end of the positive electrode column 42 close to the aluminum plate 43, and the welding annular groove 423 surrounds the injection hole 422. The aluminum plate 43 is welded in the welding annular groove 423. The aluminum plate 43 is welded in the welding annular groove 423, which can increase the welding area between the aluminum plate 43 and the positive electrode column 42, make the welding more firm, and enhance the structural stability. In some embodiments, a ring-shaped welding line is also provided at one end of the positive electrode column 42 away from the aluminum plate 43, and the welding line forms a protrusion 424 on the end surface of the positive electrode column 42, which is conducive to accurately welding the welding line to the welding area 410 of the positive current collecting plate 41.

[0054] Please also read Figure 7 and Figure 8 The aluminum plate 43 is a circular sheet structure, and a third through hole 431 is provided through the center of the aluminum plate 43. At the same time, the third through hole 431 is also a welding hole for the positive electrode column 42. Through laser welding, the aluminum plate 43 and the positive electrode column 42 can be connected.

[0055] In some embodiments, the surface of the aluminum plate 43 near the positive pole 42 is provided with an annular explosion-proof score line 432, and the explosion-proof score line surrounds the third through hole 431 of the aluminum plate. Specifically, the explosion-proof score line 432 is formed by thinning the thickness through a laser engraving process, reducing the degree of pressure resistance here, and when the internal pressure reaches a certain level, this place will be broken, and the internal gas will be discharged from the battery cell, and the explosion-proof score line 432 is annular. After the explosion-proof score line 432 is broken, the positive pole 42 and the aluminum plate 43 are cut off from conduction, which greatly ensures the safety of the battery cell during use.

[0056] The sealing bead 44 is a spherical sealing steel bead, which is welded in the second through hole 421 of the positive pole 42 and is used to seal the second through hole 421 after the first vacuum injection, opening formation and the second vacuum injection. The sealing steel bead is used to seal the second through hole 421, so that the gas generated by the battery cell during operation cannot affect the traditional screws, the electrolyte will not overflow, and the internal environment of the battery cell is effectively guaranteed, thereby extending the service life of the battery cell.

[0057] The lithium-ion battery 100 provided in this embodiment, the positive electrode current collecting plate assembly 40 also includes an upper cover plate 45, the upper cover plate 45 is fixed on the aluminum plate 43, the edge of the upper cover plate 45 is flush with the edge of the aluminum plate 43, and the upper cover plate 45 is used to further ensure the sealing of the battery. In some embodiments, the edge of the aluminum plate 43 also extends outward to form a rim 433, the rim 433 is bent in a direction close to the upper cover plate 45, and the bent rim 433 is fixed to the upper cover plate 45 by laser welding, that is, the edge of the aluminum plate 43 wraps the upper cover plate 45, the upper cover plate 45 is welded more firmly, and the deformation coefficient when the upper cover plate is packaged can be reduced. The aluminum plate 43 plays the role of conducting the positive electrode column and the upper cover plate and relieving pressure.

[0058] See also Fig. 9 In some embodiments, the positive electrode current collecting disc assembly 40 further includes a sealing ring 46, which is an annular rubber ring. The sealing ring 46 has the function of isolating the positive and negative electrodes and preventing the electrolyte from penetrating. Specifically, the sealing ring 46 includes a top wall 461, a bottom wall 462, and a side wall 463 connecting the top wall 461 and the bottom wall 462. Specifically, the top wall 461 and the bottom wall 462 are both arranged perpendicular to the side wall 463, and the aluminum plate 43 and the upper cover plate 45 are clamped between the top wall 461 and the bottom wall 462.

[0059] In this embodiment, the bottom wall 462 is provided with a lower water stop rib 464, which has the function of preventing the electrolyte from penetrating from the contact surface between the aluminum plate and the sealing ring after packaging. A waterproof groove 460 can be formed between the lower water stop rib 464 and the side wall 463, and the waterproof groove 460 can further prevent the electrolyte from overflowing. The bottom wall 462 also extends away from the top wall 461 to form a bottom water stop rib 465, which has the function of preventing the electrolyte from penetrating from the contact surface between the steel shell and the sealing ring after packaging, further ensuring the sealing of the battery. In other embodiments, the side wall 463 can also be provided with a side waterproof rib to prevent the electrolyte from penetrating from the contact surface between the aluminum plate and the sealing ring.

[0060] The lithium ion battery 100 provided by the present invention is a battery structure with a breaking function that can be used for secondary liquid injection, formation, and exhaust. This battery structure can change the traditional primary liquid injection to achieve secondary liquid injection, which can greatly improve the liquid injection efficiency. It can change the traditional closed-mouth formation to achieve open-mouth formation, and the gas generated during the formation can be discharged from the interior of the battery cell. This battery structure is reliably sealed after packaging. The secondary liquid injection can make the electrode better infiltrated with electrolyte, thereby increasing the service life of the battery cell. The open-mouth formation can discharge the gas generated during the formation from the interior of the battery cell, providing space for the secondary liquid injection and reducing the internal pressure, thereby increasing the safety and service life of the product. The sealing is reliable, ensuring the safety of the product. Sealing is performed by sealing steel balls, ensuring that the gas generated by the battery cell during operation cannot affect the traditional screws, and the electrolyte will not overflow, effectively ensuring the internal environment of the battery cell and extending the service life of the battery cell.

[0061] See also Fig.10 The present invention also provides a method for injecting liquid into a lithium-ion battery based on the above embodiment, and the method comprises the following steps:

[0062] S10, primary vacuum injection: injecting electrolyte into the shell for the first time, the electrolyte flows through the third through hole, the second through hole, the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell;

[0063] S20, opening forming: forming when the second through hole is not sealed;

[0064] S30, secondary vacuum injection: injecting electrolyte into the shell for the second time, the electrolyte flows through the third through hole, the second through hole, the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell;

[0065] S40, sealing: welding a sealing bead into the second through hole of the positive electrode column to seal the second through hole.

[0066] In this embodiment, vacuum injection is first performed, and the electrolyte flows through the third through hole, the second through hole, and the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell, and then opening formation is performed. The battery after formation is then injected with a second injection. The use of the second injection can ensure that the electrode is infiltrated with the electrolyte. The open formation can discharge the gas generated during the formation into the battery cell, which provides space for the second injection and reduces the internal pressure, thereby increasing the safety and life of the product. Finally, it is sealed with sealing beads, and the sealing is reliable, thereby ensuring the safety of the product.

[0067] In some implementations, step S10 further includes:

[0068] Inserting a rubber plug into the second through hole for temporary sealing;

[0069] The temporarily sealed lithium-ion battery is placed in a high temperature static state, the high temperature static state environment is -45℃ dew point, the temperature is 45±2℃, and the high temperature static state time is 48h;

[0070] After high temperature quiescence, the rubber plug is pulled out and then the opening is formed.

[0071] In this embodiment, the plugging and unplugging of the rubber plug is carried out in an internal microenvironment with a dew point of -45°C and a temperature of 23+3°C. The temporary sealing can prevent the electrolyte from volatilizing during the electrolyte infiltration of the electrode, thereby ensuring the electrode infiltration effect.

[0072] In some embodiments, the injection volume of the first vacuum injection is 85-90% of the total injection volume, and the injection time of the first vacuum injection is 50 minutes; the injection volume of the second vacuum injection is 10-15% of the total injection volume, and the injection time of the second vacuum injection is 30 minutes.

[0073] In this embodiment, by reasonably controlling the injection amount and injection time of the first vacuum injection and the second vacuum injection, the electrode can be better infiltrated with the electrolyte, the injection efficiency is greatly improved, and the service life of the battery cell can be increased.

[0074] In some embodiments, the environmental parameters of the environment in which the primary vacuum injection and the secondary vacuum injection are located are: internal microenvironment -45°C dew point, temperature 23+3°C, external environment -30°C dew point, temperature 23±3°C. The injection environment is divided into an internal microenvironment and an external environment, and different environmental parameters are used to ensure the fluidity of the electrolyte, shorten the time for the electrolyte to be absorbed, facilitate the electrolyte infiltration effect and improve the injection efficiency. The dew point of the internal microenvironment is strictly controlled to -45°C, which can ensure that the electrolyte does not absorb water.

[0075] In some embodiments, the step of forming the opening comprises:

[0076] After standing for 1 minute, charge at 0.05C constant current for 120 minutes, and then charge at 0.15C constant current for 90 minutes to 30% SOC;

[0077] The first OCV test is performed after the opening is formed.

[0078] Specifically, the open formation is carried out in the above-mentioned internal microenvironment. The open formation discharges the gas generated during the formation into the battery cell, provides space for the secondary liquid injection and reduces the internal pressure, thereby increasing the safety and life of the product. The formation has two main functions: one is to convert the active substances in the battery into substances with normal electrochemical effects with the help of the first charge, and the other is to form an effective passivation film or SEI film on the electrode, mainly the negative electrode. Using reasonable parameters for formation can better activate the battery and improve the electrochemical performance of the battery.

[0079] The benefits of using small current to form lithium batteries are mainly reflected in the following aspects:

[0080] Extend battery life: Low current formation helps avoid overcharging and over-discharging, which are the two main factors affecting battery life. By controlling the current to charge at a lower level, the battery can be kept in a relatively stable state of charge, thereby reducing battery loss and extending its service life. Improve battery performance: Low current charging allows lithium ions to be deposited more evenly in the electrode material, which helps to improve the performance of the battery. In addition, low current formation is also conducive to the formation of a dense and stable solid electrolyte interface (SEI) film, which helps to improve the stability and performance of the battery. Improve battery safety: High current charging often causes battery overheating and gas emission, increasing the safety risk of the battery. In contrast, low current charging can reduce this risk and make the battery more stable and safe during the charging process. Optimize the battery formation process: In the formation process, low current formation is an important link in the production of lithium batteries. It helps to activate the active substances in the battery and promote the formation of the SEI film. Although the low current formation time is longer, it can form a more dense and stable SEI film, which is crucial to improving the cycle stability of the battery and extending its service life. Adapt to different application scenarios: For devices that require long standby time and high-quality performance, low-current charging and formation are more suitable choices. These devices often have high requirements for battery life and performance, and low-current charging and formation can just meet these requirements. Reduce electrolyte volatilization: Under low-current conditions, the battery generates less heat, the internal temperature of the battery and the ambient temperature are not much different, the speed of gas generated by internal reactions is low, and the gas exhalation is gentle, which helps to reduce the volatilization of the electrolyte. The electrolyte is an important component of the battery, and its reduced volatilization helps maintain the performance and stability of the battery. In summary, the benefits of lithium battery low-current formation are mainly reflected in extending battery life, improving battery performance, improving battery safety, optimizing the battery formation process, adapting to different application scenarios, and reducing electrolyte volatilization. These benefits have made low-current formation widely used and valued in lithium battery production.

[0081] See also Fig.11 , which is a flow chart of a method for injecting lithium-ion batteries provided by another embodiment of the present invention. In this embodiment, the lithium-ion batteries are sealed with sealing beads and then cleaned, glued, welded, oiled, assembled, kept at high temperature for 48 hours, tested for the second OCV test, recharged, kept at high temperature for 7 days, kept at room temperature for 12 hours, and tested for the third OCV test before capacity division, inspection, and shipment. Specifically, environment: the overall cleaning of the battery and the environmental control of the previous working steps are 100,000 level, and then 1 million level. The recharging process includes: after standing for 1 minute, charging at 0.2C constant current and constant voltage to 3.65V, with a cut-off current of 0.05C and a time of 240 minutes, and recharging to 100% SOC.

[0082] This embodiment shows the entire process of the lithium-ion battery injection method. With such a design, secondary injection is performed to ensure that the electrode is wetted with electrolyte, and the opening is formed. The gas generated in the formation stage can be discharged, and the sealing is performed by sealing steel balls to ensure that the gas generated by the battery cell during operation cannot affect the screws, and the electrolyte will not overflow, thereby effectively protecting the internal environment of the battery cell and extending the service life of the battery cell.

[0083] It can be understood that all embodiments of the lithium-ion battery 100 provided by the present invention are applicable to the lithium-ion battery injection method provided by the present invention, and can achieve the same or similar technical effects.

[0084] In summary, the lithium-ion battery 100 and the preparation method thereof provided by the present invention, the first surface 411 of the positive current collecting disk 41 is welded to the positive terminal surface 202 of the battery cell 20, one end of the positive electrode column 42 is welded to the second surface 412 of the positive current collecting disk 41, and the other end of the positive electrode column 42 is welded to the aluminum plate 43. The center of the positive current collecting disk 41 is provided with a first through hole 401 penetrating the first surface 411 and the second surface 422, the center of the positive electrode column 42 is provided with a second through hole 421 penetrating therethrough, and the center of the aluminum plate 43 is provided with a third through hole 431 penetrating therethrough, and the first through hole 401, the second through hole 421, and the third through hole 431 are positioned relative to each other, and the electrolyte can flow through the first through hole 401, the second through hole 421, and the third through hole 431 and be injected into the shell 10 to soak The battery cell 20 is moistened because the positive electrode column 42 is provided with a second through hole 421, and open formation can be achieved after the first injection. After the open formation, the first through hole 401, the second through hole 421, and the third through hole 431 are used for secondary injection. After the secondary injection, the sealing bead 44 is welded in the second through hole 421 of the positive electrode column 42 to seal the second through hole 421. This battery structure can change the traditional primary injection and realize secondary injection, greatly improving the injection efficiency. The secondary injection can make the electrode better infiltrated with the electrolyte, thereby increasing the service life of the battery cell. This battery structure can change the traditional closed-mouth formation and realize open formation, and the gas generated during the formation is discharged from the inside of the battery cell, providing space for the secondary injection and reducing the internal pressure, thereby increasing the safety and life of the product.

[0085] The above description is only an implementation mode of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A lithium ion battery, characterized in that: It comprises a shell with an opening at one end, a battery cell contained in the shell, a negative current collector and a positive current collector assembly; the negative current collector is welded to the negative end surface of the battery cell, and the positive current collector assembly is arranged at one end of the shell opening; The positive current collector assembly includes a positive current collector, a positive electrode column, an aluminum plate and a sealing bead; the positive current collector includes a first surface and a second surface opposite to the first surface, the first surface of the positive current collector is welded to the positive end surface of the battery cell, one end of the positive electrode column is welded to the second surface of the positive current collector, and the other end of the positive electrode column is welded to the aluminum plate; a first through hole penetrating the first surface and the second surface is provided at the center of the positive current collector, a second through hole penetrating the center of the positive electrode column is provided, and a third through hole penetrating the center of the aluminum plate is provided, and the first through hole, the second through hole and the third through hole are positioned relatively; the first through hole, the second through hole and the third through hole are used to inject electrolyte into the shell, the sealing bead is welded in the second through hole of the positive electrode column, and the sealing bead is used to seal the second through hole after a vacuum injection, an opening formation and a second vacuum injection.

2. The lithium-ion battery according to claim 1, characterized in that An injection hole is provided at one end of the positive electrode column close to the aluminum plate. The injection hole is connected to the second through hole. The diameter of the injection hole gradually decreases in a direction away from the aluminum plate.

3. The lithium ion battery according to claim 2, characterized in that A welding ring groove is formed at one end of the positive electrode column close to the aluminum plate. The welding ring groove surrounds the liquid injection hole, and the aluminum plate is welded in the welding ring groove.

4. The lithium ion battery according to any one of claims 1 to 3, characterized in that: A ring-shaped explosion-proof engraved line is provided on the surface of the aluminum plate close to the positive electrode column, and the explosion-proof engraved line surrounds the third through hole of the aluminum plate.

5. A method for injecting liquid into a lithium ion battery, characterized in that: The lithium-ion battery comprises a shell with an opening at one end, a battery cell contained in the shell, a negative current collector and a positive current collector assembly; the negative current collector is welded to the negative end surface of the battery cell, and the positive current collector assembly is arranged at one end of the shell opening; The positive current collector assembly comprises a positive current collector, a positive electrode column, an aluminum plate and a sealing bead; the positive current collector comprises a first surface and a second surface opposite to the first surface, the first surface of the positive current collector is welded to the positive terminal surface of the battery cell, one end of the positive electrode column is welded to the second surface of the positive current collector, and the other end of the positive electrode column is welded to the aluminum plate; a first through hole penetrating the first surface and the second surface is provided at the center of the positive current collector, a second through hole penetrating the positive electrode column is provided at the center, and a third through hole penetrating the positive electrode column is provided at the center, and the first through hole, the second through hole and the third through hole are positioned relatively to each other; The liquid injection method comprises the following steps: Primary vacuum injection: injecting electrolyte into the shell for the first time, the electrolyte flows through the third through hole, the second through hole, the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell; Opening formation: Forming is performed when the second through hole is not sealed; Secondary vacuum injection: injecting electrolyte into the shell for the second time, the electrolyte flows through the third through hole, the second through hole, the first through hole in sequence, and the electrolyte infiltrates the battery cell in the shell; Sealing: welding a sealing bead into the second through hole of the positive electrode column to seal the second through hole.

6. The method for injecting liquid into a lithium ion battery according to claim 5, wherein: After a vacuum injection, the following steps are also included: Inserting a rubber plug into the second through hole for temporary sealing; The temporarily sealed lithium-ion battery is placed in a high temperature static state, the high temperature static state environment is -45℃ dew point, the temperature is 45±2℃, and the high temperature static state time is 48h; After high temperature quiescence, the rubber plug is pulled out and then the opening is formed.

7. The method for injecting liquid into a lithium ion battery according to claim 5, wherein: The injection volume of the first vacuum injection is 85-90% of the total injection volume, and the injection time of the first vacuum injection is 50 minutes; the injection volume of the second vacuum injection is 10-15% of the total injection volume, and the injection time of the second vacuum injection is 30 minutes.

8. The method for injecting liquid into a lithium ion battery according to claim 5, wherein: The environmental parameters of the environment in which the primary vacuum liquid injection and the secondary vacuum liquid injection are located are: internal microenvironment -45°C dew point, temperature 23+3°C, external environment -30°C dew point, temperature 23±3°C.

9. The method for injecting liquid into a lithium ion battery according to claim 5, wherein: The step of forming the opening comprises: After standing for 1 minute, charge at 0.05C constant current for 120 minutes, and then charge at 0.15C constant current for 90 minutes to 30% SOC; The first OCV test is performed after the opening is formed.

10. The method for injecting liquid into a lithium ion battery according to any one of claims 5 to 9, characterized in that: After the lithium-ion battery is sealed with sealing beads, it is cleaned, the sealing beads are glued, the seals are welded, oiled, assembled, kept at high temperature for 48 hours, the second OCV test is performed, the battery is recharged, kept at high temperature for 7 days, kept at room temperature for 12 hours, and the third OCV test is performed before capacity division, testing, and shipment.

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