Lithium ion energy storage battery

Abstract

The utility model relates to the technical field of energy storage batteries, in particular to a lithium ion energy storage battery which comprises a shell, and a battery cell and a lithium source which are arranged in the shell, wherein the battery cell comprises a positive plate, a diaphragm and a negative plate which are matched for use; the positive plate is provided with a positive tab at least partially extending out of the outer side of the shell, and the negative plate is provided with a negative tab at least partially extending out of the outer side of the shell; the lithium source is connected with the negative tab through the metal foil; and the lithium source is suitable for releasing active lithium, and the lithium source is arranged below the battery core, so that the released active lithium is suitable for being transferred into the battery core from bottom to top. The lithium source suitable for releasing active lithium is arranged in the shell and is independent of the positive plate and the negative plate, so that the released active lithium cannot influence the positive plate and the negative plate, and side reaction in the pre-lithiation process is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage batteries, in particular to a lithium ion energy storage battery. Background Art

[0002] Lithium batteries are widely used in aerospace, computers, mobile communication equipment, robots and electric vehicles due to their high energy density, long cycle life and wide applicable temperature range. In order to achieve higher energy storage performance, the energy density of lithium-ion energy storage batteries needs to be further improved to achieve better results. During the first discharge of lithium-ion energy storage batteries, a solid electrolyte film will form on the surface of the negative electrode. The formation of the solid electrolyte film will consume lithium from the positive electrode material, and the process is irreversible. The solid electrolyte interface film is lithium ion conductive but not electron conductive, which can prevent solvent molecules from being co-embedded in the negative electrode and prevent solvent molecules from damaging the negative electrode material. However, the lithium source consumed by the solid electrolyte film reduces the coulombic efficiency of the battery in the first cycle, and a pre-lithiation solution needs to be designed to compensate for this part of lithium to achieve a higher energy density.

[0003] The existing pre-lithiation methods include lithium replenishment of positive and negative electrodes (lithium strip rolling lithium replenishment, lithium powder replenishment, lithiated negative electrode materials, lithium-rich positive electrode materials and positive electrode lithium-rich additives, etc.). These methods face problems such as high processing difficulty and high safety risks. Specifically:

[0004] Lithium metal replenishment is to directly compound lithium metal with the negative electrode and distribute it in the negative electrode plate. The reaction area is large and there are many side reactions. At the same time, the dead lithium produced by the side reactions will block the surface pores of the plate in the area covered by lithium metal, which will deteriorate the dynamics. The amount of lithium replenishment is difficult to control. If the amount of lithium replenishment is insufficient, the effect is not obvious. If the amount of lithium replenishment is excessive, the performance of the battery cell will be affected. In view of the high activity of lithium metal, the shelf life of the lithium replenishment plate is short, and the time control requirements for production are high.

[0005] The synthesis of lithium-ion negative electrode materials has high requirements and the cost is uncontrollable; lithium-ion negative electrode materials are generally highly active, and the preservation and processing of materials have high environmental requirements, making industrialization difficult.

[0006] Lithium replenishment in the positive electrode. The amount of lithium replenished by the lithium-rich positive electrode material is limited, and the initial efficiency improvement is not obvious; the residue after lithium replenishment needs to have higher electrochemical and structural stability, otherwise it will deteriorate the performance of the battery cell.

[0007] Lithium-rich additives: Some additives are unstable in the air and difficult to process; organic lithium salt additives have poor electronic conductivity and high decomposition voltage.

[0008] In summary, in order to address the problems existing in the pre-lithiation methods in the prior art, further research is needed on the pre-lithiation process of lithium-ion energy storage batteries. Utility Model Content

[0009] The utility model aims to provide a lithium-ion energy storage battery to solve the technical problem of facilitating optimization of its pre-lithiation process.

[0010] The lithium-ion energy storage battery of the utility model is realized as follows:

[0011] A lithium-ion energy storage battery, comprising:

[0012] A shell, and a battery cell and a lithium source arranged in the shell; wherein

[0013] The battery cell comprises a positive electrode sheet, a separator and a negative electrode sheet used together; the positive electrode sheet is provided with a positive electrode tab at least partially extending outside the shell, and the negative electrode sheet is provided with a negative electrode tab at least partially extending outside the shell;

[0014] The lithium source is connected to the negative electrode tab via a metal foil; and

[0015] The lithium source is suitable for releasing active lithium, and the lithium source is arranged below the battery cell so that the active lithium released by the lithium source is suitable for transferring into the battery cell from bottom to top.

[0016] In an optional implementation of the present invention, the metal foil is in a T-shaped structure, which includes a connecting portion for connecting to a lithium source, and an extending portion vertically connected to the connecting portion for connecting to the negative electrode tab.

[0017] In an optional implementation of the present invention, the connecting portion is composited on a lithium source; and

[0018] The lithium source composite connection part is then wrapped on its outer surface to form an elastic liquid absorbing material layer.

[0019] In an optional implementation of the present invention, a bottom support plate is further provided in the housing, and the bottom support plate is located below the battery cell; and

[0020] The lithium source is placed on the bottom support plate so that the lithium source faces the bottom of the battery cell;

[0021] The connecting portion is compounded on the side end of the lithium source facing the bottom supporting plate.

[0022] In an optional implementation of the present invention, the lithium source includes a current collector and a lithium supplement material located on the current collector.

[0023] In an optional implementation of the present invention, the current collector includes copper foil and / or aluminum foil; and

[0024] The lithium supplement material includes a positive electrode lithium supplement agent, a binder, a dispersant and a conductive agent.

[0025] In an optional implementation of the present invention, the metal foil is copper foil, nickel foil or platinum foil.

[0026] In an optional implementation of the present invention, the metal foil is connected to the negative electrode tab via a metal wire, a metal sheet or directly welded.

[0027] In an optional implementation of the utility model, the diaphragm includes a main body portion for being sandwiched between the positive electrode sheet and the negative electrode sheet, and a connecting portion forming a T-shaped structure with the main body portion; wherein

[0028] The connecting portion is sandwiched between the side ends of the positive electrode sheet and the negative electrode sheet facing the lithium source and the lithium source.

[0029] In an optional implementation of the present invention, the thickness of the lithium source does not exceed the thickness of the connecting portion.

[0030] By adopting the above technical solution, the utility model has the following beneficial effects: the lithium-ion energy storage battery of the utility model is provided with a lithium source suitable for releasing active lithium in the shell, and the lithium power source is independent of the positive electrode sheet and the negative electrode sheet, so that the released active lithium will not affect the positive electrode sheet and the negative electrode sheet themselves, thereby greatly reducing the side reactions in the pre-lithiation process.

[0031] The lithium-ion energy storage battery with this structure can solve the problems of long electrochemical pre-lithiation time, low pre-lithiation amount, uneven pre-lithiation, and dissolution of metal lithium particles. It has low environmental requirements, making pre-lithiation simple and easy to industrialize, and low cost. The lithium supplement agent is applied separately to the current collector as a lithium source to avoid the residual products of lithium supplement agent de-lithiation from affecting the positive electrode after the pre-lithiation is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a schematic diagram of the internal structure of the lithium-ion energy storage battery of the utility model;

[0033] Figure 2 Shown is a schematic diagram of the pre-lithiation principle of the lithium-ion energy storage battery of the present invention.

[0034] In the figure: shell 1, positive electrode sheet 21, negative electrode sheet 22, diaphragm 3, main body 31, connecting part 32, lithium source 4, negative electrode tab 51, positive electrode tab 52, bottom support plate 6, metal foil 7, connecting part 71, and extending part 72. DETAILED DESCRIPTION

[0035] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings.

[0036] See also Figure 1 and Figure 2 As shown, this embodiment provides a lithium-ion energy storage battery, including: a shell 1, and a battery cell and a lithium source 4 arranged in the shell 1.

[0037] Specifically, first is the battery cell, which includes a positive electrode sheet 21, a separator 3 and a negative electrode sheet 22 used together; the positive electrode sheet 21 is provided with a positive electrode tab 52 that at least partially extends outside the shell 1, and the negative electrode sheet 22 is provided with a negative electrode tab 51 that at least partially extends outside the shell 1.

[0038] Furthermore, taking an optional implementation as an example, the diaphragm 3 includes a main body 31 for being sandwiched between the positive electrode sheet 21 and the negative electrode sheet 22, and a connecting portion 32 forming a T-shaped structure with the main body 31; wherein the connecting portion 32 is sandwiched between the side ends of the positive electrode sheet 21 and the negative electrode sheet 22 facing the lithium source 4 and the lithium source 4.

[0039] In addition, a bottom support plate 6 is provided in the housing 1, and the bottom support plate 6 is located below the battery cell; and the lithium source 4 is placed on the bottom support plate 6 so that the lithium source 4 faces the bottom of the battery cell. Optionally, a space of 3 to 5 mm in thickness is reserved on the bottom support plate 6 to place the lithium source 4, so as to fix the lithium source 4.

[0040] Next, we will explain the lithium source 4:

[0041] Generally speaking, the lithium source 4 built into the housing 1 of this embodiment is suitable for releasing active lithium, and considering the lithium ion transmission path problem, the lithium source 4 is arranged below the battery cell so that the active lithium released by it is suitable for being transferred from bottom to top into the battery cell, so that the lithium ion transmission distance between the lithium source 4 and the negative electrode is shorter, and a high rate can be used for charging during formation, shortening the lithium replenishment charging time. Since the lithium power source is independent of the positive electrode sheet 21 and the negative electrode sheet 22, the released active lithium will not affect the positive electrode sheet 21 and the negative electrode sheet 22 themselves, greatly reducing side reactions.

[0042] More specifically, the lithium source 4 used in this embodiment includes a current collector and a lithium supplement material located on the current collector. The current collector includes copper foil and / or aluminum foil; and the lithium supplement material includes a positive electrode lithium supplement agent, a binder, a dispersant and a conductive agent. The optional positive electrode lithium supplement agent here includes a ternary and / or binary positive electrode lithium supplement agent; the positive electrode lithium supplement agent includes any one of Li 5 FeO 4 , Li 2NiO 2 or Li 2 O or a combination of at least two; the binder includes styrene-butadiene rubber and / or polyacrylic acid; the dispersant includes isopropanolamine and / or polyester dispersant; the conductive agent includes any one of conductive carbon, carbon nanotubes or graphene or a combination of at least two.

[0043] It should be noted that, in an optional implementation, the thickness of the lithium source 4 does not exceed the thickness of the connecting portion 32. The reason for this design is that when the thickness of the lithium source 4 is too thick, it is not conducive to the lithium desorption reaction of the lithium supplement agent on the lithium source 4, and the charging rate during lithium supplementation is reduced. The lithium content of the lithium source 4 should be moderate, neither too much to cause lithium precipitation, nor too little to meet the pre-lithium content requirements, and the lithium supplementation needs during the cycle should also be considered. In other words, the thickness of the lithium source 4 should be moderate, so that it can be placed in the space where it is placed, and it should not fall off during the pre-lithiation process, and at the same time, the lithium can be completely consumed at the end of the pre-lithiation.

[0044] Based on the above situation, it should be noted that the lithium source 4 in this embodiment is connected to the negative electrode tab 51 through the metal foil 7 .

[0045] An optional method is described in detail with reference to the accompanying drawings:

[0046] The metal foil 7 is generally T-shaped, and includes a connection portion 71 for connecting to the lithium source 4, and an extension portion 72 vertically connected to the connection portion 71 for connecting to the negative electrode tab 51. In terms of material, the metal foil 7 is copper foil, nickel foil or platinum foil.

[0047] In terms of the overall structure, the connecting portion 71 is composited on the lithium source 4; and the extension portion 72 is connected to the negative electrode tab 51 by a metal wire, a metal sheet or directly welded, for example, but not limited to, the extension portion 72 of the metal foil 7 is connected to the negative electrode tab 51 by ultrasonic welding. The metal wire, metal sheet or welding position used to achieve the connection are all located inside the shell 1. In this case, the connection inside the shell 1 can improve safety and avoid leakage caused by the connection point formed by the extension portion 72 and the negative electrode tab 51 extending out of the shell 1. At the same time, the production process is greatly simplified. In this way, after the electrolyte is injected, the negative electrode immediately begins to pre-lithiate without the need for an external load.

[0048] Here, in an optional implementation, the metal foil 7 can be first bonded with the tape and then compounded with the lithium source 4, which can increase the strength of the copper foil and avoid lithium supplementation failure caused by the breakage of the metal foil 7 during assembly and use.

[0049] Based on the above structure, in an optional implementation, this embodiment can also be modified in the following manner:

[0050] After the composite connection part 71 of the lithium source 4 is wrapped on its outer surface, an elastic liquid-absorbing material layer is formed. By setting the elastic liquid-absorbing material layer, the elastic liquid-absorbing material layer adopts, for example but not limited to, a diaphragm, on the one hand, the dissolution and shedding of the metal lithium on the lithium source 4 can be avoided, the battery cell can be elastically constrained, and the structural stability inside the lithium-ion energy storage battery can be improved. On the other hand, it can ensure that there is enough electrolyte in the pre-lithiation process. By wrapping with an elastic material, in the pre-lithiation process, along with the consumption of the lithium source 4 composite sheet, the elastic material is deformed, and can fill the space left after consumption, thereby improving the structural stability.

[0051] In summary, for the lithium-ion energy storage battery of this embodiment, the specific pre-lithiation implementation principle is as follows:

[0052] For the lithium-ion energy storage battery of the present embodiment, it can be understood that in the conventional lithium-ion energy storage battery manufacturing process, before injecting the electrolyte, a lithium source 4 is set below the battery cell, and the lithium source 4 is connected to the negative electrode tab 51 through the metal foil 7. After completing the above process, the electrolyte is injected, and the electrolyte is immersed in the lithium source 4, and the negative electrode is pre-lithiated. Pre-lithiation can be completed during the process of battery cell infiltration, formation, and volume separation. At the same time, the metal foil 7 is directly connected to the negative electrode tab 51 and the connection is controlled within the shell 1 of the lithium-ion energy storage battery. It can also avoid the safety problems that are easily caused by setting up the pre-lithiation tab separately and extending it outside the battery shell 1. In addition, the lithium-ion energy storage battery based on the present embodiment can make the lithium of the lithium source 4 completely consumed during the pre-lithiation process, and it will not remain inside the battery, reducing safety hazards.

[0053] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0054] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] In the present utility model, unless otherwise clearly specified and limited, the first feature being above or below the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, the first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A lithium-ion energy storage battery, characterized in that: include: A shell, and a battery cell and a lithium source arranged in the shell; wherein The battery cell comprises a positive electrode sheet, a separator and a negative electrode sheet used together; the positive electrode sheet is provided with a positive electrode tab at least partially extending outside the shell, and the negative electrode sheet is provided with a negative electrode tab at least partially extending outside the shell; The lithium source is connected to the negative electrode tab via a metal foil; and The lithium source is suitable for releasing active lithium, and the lithium source is arranged below the battery cell so that the active lithium released by the lithium source is suitable for transferring into the battery cell from bottom to top.

2. The lithium-ion energy storage battery according to claim 1, characterized in that: The metal foil has a T-shaped structure, which includes a connecting portion for connecting to a lithium source, and an extending portion vertically connected to the connecting portion and for connecting to the negative electrode tab.

3. The lithium-ion energy storage battery according to claim 2, characterized in that: The connecting portion is composited on the lithium source; and The lithium source composite connection part is then wrapped on its outer surface to form an elastic liquid absorbing material layer.

4. The lithium-ion energy storage battery according to claim 3, characterized in that: A bottom support plate is also provided in the housing, and the bottom support plate is located below the battery core; and The lithium source is placed on the bottom support plate so that the lithium source faces the bottom of the battery cell; The connecting portion is compounded on the side end of the lithium source facing the bottom supporting plate.

5. The lithium-ion energy storage battery according to any one of claims 1 to 4, characterized in that: The lithium source includes a current collector and a lithium supplement material located on the current collector.

6. The lithium-ion energy storage battery according to any one of claims 1 to 4, characterized in that: The metal foil is copper foil, nickel foil or platinum foil.

7. The lithium-ion energy storage battery according to claim 1, characterized in that: The metal foil is connected to the negative electrode tab via a metal wire, a metal sheet or directly welded.

8. The lithium-ion energy storage battery according to claim 1, characterized in that: The diaphragm includes a main body portion for being sandwiched between the positive electrode sheet and the negative electrode sheet, and a connecting portion forming a T-shaped structure with the main body portion; wherein The connecting portion is sandwiched between the side ends of the positive electrode sheet and the negative electrode sheet facing the lithium source and the lithium source.

9. The lithium-ion energy storage battery according to claim 1, characterized in that: The thickness of the lithium source does not exceed the thickness of the connecting portion.

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