CN219123295U

CN219123295U - Uniform pre-lithium structure of soft-package lithium battery

Info

Publication number: CN219123295U
Application number: CN202222860439.4U
Authority: CN
Inventors: 段利强; 王义飞; 申永宽; 庄华杰
Original assignee: Gotion High Tech Co Ltd
Current assignee: Gotion High Tech Co Ltd
Priority date: 2022-10-28
Filing date: 2022-10-28
Publication date: 2023-06-02
Anticipated expiration: 2032-10-28

Abstract

The utility model discloses a uniform pre-lithium structure of a soft-package lithium battery, which comprises a battery cell, an aluminum plastic film and a pre-lithium module; the battery cell comprises an anode, a cathode and electrolyte; the pre-lithium module comprises a lithium source, a current collector, a wire and an adjustable resistor; the aluminum plastic film is divided into a battery cell area for placing a battery cell and an air bag area for placing a pre-lithium module; the two ends of the adjustable resistor are respectively connected with the positive electrode and the current collector through wires. According to the utility model, by arranging the adjustable resistor, the pre-lithium speed is controllable, the concentration difference polarization of lithium ions is reduced, the uniform diffusion of lithium ions in the electrolyte is ensured, the pre-lithium is uniform, the pre-lithium module can be cut off after the pre-lithium is finished, hidden danger caused by the fact that a lithium source remains in a battery is avoided, meanwhile, the lithium source can be recycled, and the cost of the lithium source is reduced.

Description

Uniform pre-lithium structure of soft-package lithium battery

Technical Field

The utility model relates to the technical field of lithium battery pre-lithium, in particular to a soft package lithium battery uniform pre-lithium structure.

Background

Lithium ion batteries have been widely used in small electronic products, pure electric vehicles, and energy storage grids. The lithium ion battery is composed of a positive electrode which is a lithium-containing compound, a negative electrode which is a carbon-based or silicon-based compound, and an electrolyte which is an organic solvent containing lithium salt. A solid electrolyte interface film (SEI) may form on the surface of the negative electrode tab during the first charge. The solid electrolyte interface film (SEI) formation process consumes a large amount of lithium, part of lithium in the positive electrode material is lost, and the process is irreversible, so that the first coulombic efficiency of the battery is low, the cycle capacity is also reduced, and the negative electrode prelithiation technique is widely used in order to improve the first coulombic efficiency of the battery and the capacity of the battery.

The pre-lithiation technology can be summarized as adding a lithium source additionally in a battery system to compensate lithium consumed when an SEI film is formed on the surface of a negative electrode, and the current method for supplementing lithium by the pre-lithiation technology comprises the following steps: external electrochemical lithium supplement, solution pre-lithium, lithium-rich compound lithium supplement and contact lithium supplement.

The contact lithium supplementing is to contact a lithium source with a negative electrode for supplementing lithium, and is specifically subdivided into welding a lithium source lug and a negative electrode tab together, rolling a lithium foil and a negative electrode together, spraying lithium powder on the surface of the negative electrode or mixing inert lithium powder with negative electrode slurry together for slurry mixing.

In the development process of industrialized pre-lithium, the problems of external electrochemistry, solution pre-lithium and lithium-rich compound lithium supplementation, such as long manufacturing time, high cost, electrolyte residue and the like still remain in a laboratory stage due to complex process, and contact lithium supplementation has been applied to mass production of batteries by some companies.

Chinese patent CN214099829U discloses a lithium ion battery with high energy density and long lifetime. The patent is characterized in that the electrode lug of the pre-lithiated electrode and the electrode lug of the negative electrode are welded together in an ultrasonic manner, and after electrolyte is injected, the lithium supplementing electrode piece and the negative electrode piece perform pre-lithiation through primary cell reaction.

Problems with the pre-lithium process of this patent: firstly, it is: lithium of the pre-lithium electrode is completely consumed, and according to a chemical reaction principle, an SEI film is formed on the surface of a lithium sheet after the lithium sheet is immersed in electrolyte, and the lithium in the part exists in the form of oxide or organic lithium and is inevitably consumed, so that a lithium source of contact pre-lithium has a certain loss; secondly, the patent mentions that uniform pre-lithium can be realized, in fact, the electrolyte is used for infiltrating the pole piece of the battery, the pole piece is slowly wetted from the side edge of the pole piece to the inside of the pole piece, the pre-wetted part reacts with the pre-lithium electrode in a primary battery, the wetting rate is far lower than the reaction speed, and the pre-lithium of the pole piece is inevitably uneven; thirdly, the lithium source can be sheared into corresponding sizes according to different pole piece sizes, the process is tedious, and time and labor are wasted.

Chinese patent CN111710918A discloses a lithium ion battery with pre-lithiated negative electrode and a method for manufacturing the same. Specifically, the method comprises the steps of calendaring lithium powder on a current collector, passivating the lithium powder to form a stable protective layer, and then coating an active material on the surface of the pre-lithiated current collector. On one hand, the uniformity of the distribution of the lithium powder on the surface of the current collector cannot be ensured, and the uneven distribution of the lithium powder can lead to the formation of lithium dendrites in the process of forming the components of the material, so that potential safety hazards exist; on the other hand, the preparation process of the pre-lithium current collector has strict environmental requirements, low universality and high production cost.

Disclosure of Invention

The utility model aims to disclose a uniform pre-lithium structure of a soft-package lithium battery, which realizes controllable pre-lithium rate, and uniform diffusion of lithium ions in electrolyte during pre-lithium, and uniform pre-lithium; the lithium source of the pre-lithium is independent, the pre-lithium module can be cut off after the pre-lithium is finished, hidden danger caused by the fact that the lithium source remains in the battery is avoided, and the energy density of the battery is not lost.

The aim of the utility model can be achieved by the following technical scheme: a soft package lithium battery uniform pre-lithium structure comprises a battery core, wherein the battery core comprises an anode, a cathode and electrolyte; the method is characterized in that: the battery cell is movably connected with a pre-lithium module; the pre-lithium module includes a lithium source, a current collector, a wire, and an adjustable resistor.

As still further aspects of the utility model: the battery cell anode is provided with an anode tab, the battery cell and the pre-lithium module are respectively arranged in an aluminum plastic film battery cell area and an air bag area, and a liquid injection port for injecting electrolyte is reserved in the air bag area; and two ends of the adjustable resistor are respectively connected with a battery cathode and a current collector through wires.

As still further aspects of the utility model: the battery cell positive electrode is provided with a positive electrode tab, after electrolyte is injected into the battery cell to be completely wetted, the negative electrode is connected with a lithium source to perform pre-lithium, and the electrolyte injection coefficient is 1.5-2.0 times of that of the battery cell without pre-lithium.

As still further aspects of the utility model: the battery cell positive electrode is provided with a positive electrode lug, the negative electrode is provided with a negative electrode lug, and the current collector is provided with a lithium source lug.

As still further aspects of the utility model: the battery cell anode is provided with an anode tab, and two ends of the adjustable resistor are respectively connected with a cathode tab and a lithium source tab through wires.

As still further aspects of the utility model: the battery cell anode is provided with an anode tab, the adjustable resistance adjusting range is 0-100mΩ, the lead is copper wire, and the resistance of the copper wire is not more than 1mΩ.

As still further aspects of the utility model: the battery cell anode is provided with an anode tab, and the current is controlled to be 0.001-0.005 ℃ by an adjustable resistor in the pre-lithium stage.

As still further aspects of the utility model: the battery cell anode is provided with an anode tab, the lithium source is a lithium copper composite belt, and the current collector is copper foil.

As still further aspects of the utility model: the battery cell positive electrode is provided with a positive electrode lug, the positive electrode and the negative electrode of the battery cell are assembled by adopting a lamination process, and the lamination process is Z-fold or winding.

As still further aspects of the utility model: the battery cell anode is provided with an anode tab, the anode material is lithium iron phosphate, ternary material or lithium manganese iron phosphate, and the cathode material is graphite or silicon-based material.

The utility model has the beneficial effects that:

according to the utility model, by arranging the adjustable resistor, the pre-lithium speed is controllable, the concentration difference polarization of lithium ions is reduced, the uniform diffusion of lithium ions in the electrolyte is ensured, the pre-lithium is uniform, the pre-lithium module can be cut off after the pre-lithium is finished, hidden danger caused by the fact that a lithium source remains in a battery is avoided, meanwhile, the lithium source can be recycled, and the cost of the lithium source is reduced.

Drawings

Fig. 1 is a schematic structural diagram of a uniform pre-lithium structure of a soft-pack lithium battery according to the present utility model;

fig. 2 is a schematic view of the structure of the pre-lithium battery installed in the fixture.

A. A clamping plate; 10. a battery cell; 111. a positive electrode tab; 121. a negative electrode tab; 20. a pre-lithium module; 21. a lithium source; 22. a current collector; 221. lithium source ear; 23. a wire; 24. an adjustable resistor; 30. an aluminum plastic film; 31. a cell region; 32. an air pocket area.

Detailed Description

Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar symbols indicate like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present utility model and are not to be construed as limiting the present utility model.

As shown in fig. 1-2, the utility model discloses a soft package lithium battery uniform pre-lithium structure, which comprises a battery cell 10, wherein the battery cell 10 comprises an anode, a cathode and electrolyte; the method is characterized in that: the battery core 10 is movably connected with a pre-lithium module 20; the pre-lithium module 20 includes a lithium source 21, a current collector 22, wires 23, and an adjustable resistor 24.

In the scheme, the adjustable resistor 24 adjusts the current passing through the lead 23 in the pre-lithium process, reduces the concentration difference polarization of lithium ions, ensures the uniform diffusion of lithium ions in the electrolyte, and ensures uniform pre-lithium. The battery core 10 is movably connected with the pre-lithium module 20, and after the pre-lithium is finished, the pre-lithium module 20 can be removed, so that hidden danger caused by the fact that a lithium source remains in the battery can be avoided.

Further, the battery cell 10 and the pre-lithium module 20 are respectively arranged in a battery cell area 31 and an air bag area 32 of the aluminum plastic film 30, and a liquid injection port for injecting electrolyte is reserved in the air bag area 32; the two ends of the adjustable resistor 24 are respectively connected with the battery cathode and the current collector 22 through leads 23.

In the scheme, the battery core 10 and the pre-lithium module 20 are arranged in the aluminum plastic film 30 in a separated mode, the pre-lithium module 20 can be cut off after the pre-lithium is finished, hidden danger is not caused by the fact that the lithium source 21 remains in the battery, meanwhile, the lithium source 21 can be recycled, and the cost of the lithium source 21 is reduced.

Further, after the battery cell 10 is completely wetted by the electrolyte, the negative electrode and the lithium source 21 are connected for pre-lithium, and the electrolyte injection coefficient is 1.5-2.0 times that of the battery cell 10 without pre-lithium; the ion conductivity of the whole pre-wetted pole piece is complete, and compared with the prior art, the pre-wetted pole piece has no pre-lithium condition.

Further, the positive electrode of the battery cell 10 is provided with a positive electrode tab 111, the negative electrode is provided with a negative electrode tab 121, and the current collector 22 is provided with a lithium source tab 221.

Further, two ends of the adjustable resistor 24 are respectively connected to the negative electrode tab 121 and the lithium source tab 221 through a wire 23. The battery cell 10 is more convenient to pre-lithium through the electrode lugs.

Further, the adjustable resistor 24 can adjust the internal resistance to be 0-100mΩ, the lead 23 is copper wire, the copper wire resistance is not more than 1mΩ, and the adjustable resistor 24 controls the current to be 0.001-0.005C in the pre-lithium stage. The pre-lithium rate is controllable, so that the concentration difference polarization of lithium ions is reduced, and the uniform diffusion of the lithium ions in the electrolyte is ensured.

Further, the positive and negative electrodes of the cell 10 are assembled by a lamination process, which is Z-stack or winding. The lamination process ensures that the battery cell 10 has high energy density and flexible size, the lamination process is to laminate the positive electrode mixture layer, the diaphragm and the negative electrode mixture layer according to the sequence, the continuity of the lamination process during Z lamination is characterized by Z-shaped bending, and the winding is rolled into a cylindrical shape or an elliptic cylindrical shape.

Further, the lithium source 21 is a lithium copper composite tape, and the current collector 22 is copper foil. Lithium source 21 and current collector 22 may also employ metallic lithium.

Further, the positive electrode material is lithium iron phosphate, ternary material or lithium iron manganese phosphate, and the negative electrode material is graphite or silicon-based material.

The pre-lithium structure is described below with examples

Embodiment one: the lithium iron phosphate is adopted as the positive electrode, the graphite is adopted as the negative electrode, the design capacity is 10.7Ah, the weight of the lithium source 21 is designed according to 5% of the initial efficiency of the pre-lithium-enhanced battery, the thickness of the lithium sheet 9 in the lithium copper composite strip is 200 mu m, and the copper foil 8 is 8 mu m;

the first step: the positive electrode, the diaphragm and the negative electrode of the battery cell 10 are formed in a Z-folded mode, after the positive electrode tab 111 and the negative electrode tab 121 are welded, the battery cell is semi-packaged by an aluminum plastic film 30, and a liquid injection port is reserved in the air bag area 32.

And a second step of: and (3) putting the packaged battery cell 10 into a vacuum drying oven for baking, wherein the moisture requirement of the battery cell 10 is less than 500ppm, then injecting liquid, wherein the liquid injection coefficient is 1.5 times that of a non-pre-lithium battery, and then the height is Wen Jinrun h.

And a third step of: the lithium copper composite strip is cut into a T shape as shown in fig. 1, and is placed close to the battery cell 10, so that the diffusion distance of lithium ions is shortened, and the electrolyte is ensured to form an ion passage between the battery cell 10 and a lithium sheet. And (3) welding the lugs of the lithium copper composite belt, extruding air in the aluminum plastic film 30 by using the clamping plate A during sealing, and sealing without negative pressure vacuumizing.

Fourth step: and connecting two ends of the adjustable resistor 24 with the negative electrode tab 121 and the lithium source tab 221 respectively by using a lead 23, adjusting the internal resistance to control the current to be 0.001-0.005C, enabling the pre-lithium voltage to reach 2.3-2.5V, ending the pre-lithium when the voltage rising rate is lower than 0.005V/h, removing the battery pre-lithium module 20, and sealing at negative pressure.

Fifth step: and (3) the battery cell 10 is formed at a high temperature of 45 ℃, then aged for 12 hours at a high temperature of 45 ℃, and finally separated.

In the second embodiment, ternary NCM811 is adopted as the positive electrode, a pure silica-graphite composite material (SiOx-C) is adopted as the negative electrode, the design capacity is 10.7Ah, the initial efficiency of the battery is improved by 8% theoretically, the thickness of a lithium sheet in the lithium copper composite belt is 100 mu m, and the copper foil is 8 mu m.

The first step: as shown in fig. 1, the battery cell 10 is configured in a Z-stack manner. After the positive electrode tab 111 and the negative electrode tab 121 are welded, semi-packaging is performed by using an aluminum plastic film 30, and a liquid injection port is reserved in the air bag area 32.

And a second step of: and (3) putting the packaged battery cell 10 into a vacuum drying oven for baking, wherein the moisture requirement of the battery cell 10 is less than 500ppm, then injecting liquid, wherein the liquid injection coefficient is 2 times that of a non-pre-lithium battery, and then the height is Wen Jinrun h.

And a third step of: the lithium copper composite strip is cut into a T shape as shown in fig. 1, and is placed close to the battery cell 10, so that the diffusion distance of lithium ions is shortened, and the electrolyte is ensured to form an ion passage between the battery cell 10 and a lithium sheet. The lithium source lugs 221 are welded, and air in the aluminum plastic film 30 is extruded by the clamping plate A during sealing, and vacuum pumping is not performed for sealing.

Fourth step: the two ends of the adjustable resistor 24 are respectively connected with the negative electrode lug 121 and the lithium source electrode lug 221 by using a lead 23, the current of the adjustable resistor 24 is controlled to be 0.001-0.003C, the pre-lithium voltage reaches 2.0-2.5V, the voltage rising rate is lower than 0.005V/h, the pre-lithium is finished, the battery is subjected to high-temperature formation at 45 ℃, the negative electrode lug 121 and the lithium source electrode lug 221 are disconnected in the formation charging stage, and the formation is fully charged and then discharged for 30% DOD. The positive electrode of the pole piece tab and the lithium source tab 221 are connected in the discharging stage, the discharging depth is 5%, then the positive electrode tab 121 and the negative electrode tab 121 of the pole piece are connected, the discharging is continued, the discharging depth is 25%, and then the high-temperature aging is carried out for 12 hours.

Fifth step: the pre-lithium module 20 is cut off when Degas is performed on the aged battery, and finally the capacity is divided.

The examples described in this utility model are only preferred embodiments, the reaction of the graphite anode with lithium is an intercalation reaction, so the fourth pre-lithium stage of embodiment one removes the pre-lithium module 20, pure SiO _x In the-C system, siO _x Is a conversion reaction with lithium and has a relatively large volume expansion during cycling, so the pre-lithium module 20 is used in the second embodiment to supplement the positive electrode with some lithium to reduce the expansion of the negative electrode material during the early part of cycling. The utility model not only can realize uniform pre-lithium, but also can not increase the quality of the battery system and can not reduce the energy density of the battery system. Degas in the examples refers to the degassing process, and a large amount of gas is generated during the formation process, which affects the performance of the battery, so that the battery after formation is also subjected to degassing.

The present utility model is not limited to the above-mentioned embodiments, and any person skilled in the art, based on the technical solution of the present utility model and the inventive concept thereof, can be replaced or changed within the scope of the present utility model.

It is to be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counter-clockwise," "axial," "radial," "circumferential," and the like are directional or positional relationships as indicated based on the drawings, merely to facilitate describing the utility model and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

Claims

1. The uniform pre-lithium structure of the soft-package lithium battery comprises a battery cell (10), wherein the battery cell (10) comprises an anode, a cathode and electrolyte; the method is characterized in that: the battery cell (10) is movably connected with a pre-lithium module (20); the pre-lithium module (20) comprises a lithium source (21), a current collector (22), a wire (23) and an adjustable resistor (24).

2. The soft-pack lithium battery uniform pre-lithium structure according to claim 1, wherein: the battery cell (10) and the pre-lithium module (20) are respectively arranged in a battery cell area (31) and an air bag area (32) of the aluminum plastic film (30), and a liquid injection port for injecting electrolyte is reserved in the air bag area (32); and two ends of the adjustable resistor (24) are respectively connected with a battery cathode and a current collector (22) through leads (23).

3. The soft-pack lithium battery uniform pre-lithium structure according to claim 2, wherein: after the battery cell (10) is completely wetted by electrolyte, the negative electrode and the lithium source (21) are connected for pre-lithium, and the injection coefficient of the electrolyte is 1.5-2.0 times of that of the battery cell (10) without pre-lithium.

4. The soft-pack lithium battery uniform pre-lithium structure according to claim 2, wherein: the battery cell (10) positive electrode is provided with a positive electrode lug (111), the negative electrode is provided with a negative electrode lug (121), and the current collector (22) is provided with a lithium source lug (221).

5. The soft pack lithium battery uniform pre-lithium structure according to claim 4, wherein: two ends of the adjustable resistor (24) are respectively connected with the negative electrode lug (121) and the lithium source lug (221) through wires (23).

6. The soft-pack lithium battery uniform pre-lithium structure according to claim 1, wherein: the adjustable resistor (24) is adjusted to be in the range of 0-100mΩ, and the lead (23) is a copper wire with the resistance of not more than 1mΩ.

7. The soft pack lithium battery uniform pre-lithium structure according to claim 5, wherein: the pre-lithium stage adjustable resistor (24) controls the current to be 0.001-0.005C.

8. The soft-pack lithium battery uniform pre-lithium structure according to claim 1, wherein: the lithium source (21) is a lithium copper composite belt, and the current collector (22) is copper foil.

9. The soft-pack lithium battery uniform pre-lithium structure according to claim 1, wherein: the positive electrode and the negative electrode of the battery cell (10) are assembled by adopting a lamination process, and the lamination process is Z-lamination or winding.

10. The soft-pack lithium battery uniform pre-lithium structure according to claim 1, wherein: the positive electrode material is lithium iron phosphate, ternary material or lithium manganese iron phosphate, and the negative electrode material is graphite or silicon-based material.