CN214848691U - Negative plate and lithium ion battery comprising same - Google Patents
Negative plate and lithium ion battery comprising same Download PDFInfo
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- CN214848691U CN214848691U CN202121434271.XU CN202121434271U CN214848691U CN 214848691 U CN214848691 U CN 214848691U CN 202121434271 U CN202121434271 U CN 202121434271U CN 214848691 U CN214848691 U CN 214848691U
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Abstract
The utility model provides a negative pole piece, including mending the lithium layer, micropore metal forming to and active substance layer, mend the lithium layer micropore metal forming and active substance layer is according to the order lamination together of "active substance layer/micropore metal forming/mend lithium layer/micropore metal forming/active substance layer". The negative plate has the advantages of simple structure, high first coulombic efficiency, good cycle performance and controllable lithium supplement rate. Besides, the utility model discloses still provide the lithium ion battery who contains this negative pole piece, possess above-mentioned technological effect equally.
Description
Technical Field
The utility model belongs to the technical field of the electrochemistry energy storage, especially, relate to a negative pole piece and contain lithium ion battery of this negative pole piece.
Background
The lithium ion battery has the characteristics of high energy density, good cycle performance, good safety, environmental friendliness and the like, and is widely applied to consumer electronics products and power energy storage products. At present, graphite is taken as a main negative electrode material of the lithium ion battery, the theoretical specific capacity of the graphite is only 372mAh/g, and in order to further improve the energy density of the battery, a silicon material gradually becomes the first choice of the negative electrode material of the next generation of lithium ion battery.
The theoretical specific capacity of the silicon negative electrode can reach more than 4000mAh/g, and the silicon negative electrode has lower discharge potential and is a negative electrode material with great potential. However, the volume change of the silicon material is large in the process of lithium intercalation/lithium deintercalation, and reaches up to 300%, and the large volume change often causes the phenomena of active material particles such as crushing, slippage and the like, and finally causes electrode pulverization, capacity reduction and cycle life shortening. In addition, the silicon cathode has the defect of low coulombic efficiency for the first time, and generally can only reach about 70%. In order to apply a silicon negative electrode to a lithium ion battery, lithium is usually required to be supplemented to the silicon negative electrode, and the first coulombic efficiency of the silicon negative electrode is improved to a level close to that of graphite, so that the purpose of improving the energy density is achieved.
At present, a layer of lithium powder is plated on the surface of a negative electrode in a conventional lithium supplementing mode through modes of sputtering, spraying and the like, the risk that the lithium powder is easy to splash and remain exists in the conventional lithium supplementing mode, safety accidents are easy to cause, the operation process is complex, and the process requirement is high.
Therefore, how to provide a negative electrode sheet with high energy density and good cycle performance becomes a technical problem to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a negative plate, this negative plate simple structure, first coulomb is efficient, and the cyclicity can be good, and mend lithium speed controllable. Besides, the utility model discloses still provide the lithium ion battery who contains this negative pole piece, possess above-mentioned technological effect equally.
The utility model provides a negative pole piece, including mending the lithium layer, micropore metal forming to and active substance layer, mend the lithium layer micropore metal forming and active substance layer is according to the order lamination together of "active substance layer/micropore metal forming/mend lithium layer/micropore metal forming/active substance layer".
The smaller the thickness of the microporous metal foil is, the shorter the diffusion path of the lithium supplement layer is, and the faster the lithium supplement rate is, but as the thickness of the microporous metal foil is reduced, the strength of the microporous metal foil is correspondingly reduced, and the problem of band breakage in the processing of the microporous metal foil inevitably occurs in the processing process, so that the thickness of the microporous metal foil needs to be reasonably controlled.
Preferably, the thickness of the microporous metal foil is 2 to 10 μm.
Preferably, the microporous metal foil has a thickness of 4 to 6 μm.
The smaller the pore diameter of the pores of the microporous metal foil, the smaller the contact surface between the lithium supplement layer and the active material layer of the negative electrode, and the slower the diffusion rate of lithium. The larger the pore diameter of the pores of the microporous metal foil, the larger the contact surface between the lithium supplement layer and the active material layer of the negative electrode, and the faster the diffusion rate of lithium. Also, the larger the pore size, the more easily the active material slurry passes through the metal foil at the time of coating, resulting in coating unevenness or slurry loss. Therefore, it is necessary to reasonably control the pore diameter of the pores of the microporous metal foil.
Preferably, the pore diameter of the microporous metal foil is 0.1 to 5 μm.
Preferably, the pore diameter of the microporous metal foil is 0.5 to 1 μm.
The higher the surface density of the pores of the microporous metal foil is, the faster the diffusion rate of the lithium supplement layer is, but as the surface density of the pores of the microporous metal foil increases, the strength of the microporous metal foil also decreases correspondingly, and the problem of breakage of the microporous metal foil during processing inevitably occurs, so that the surface density of the pores of the microporous metal foil needs to be reasonably controlled.
Preferably, the microporous metal foil has an areal density of pores of 0.1 to 30%.
Preferably, the microporous metal foil has an areal density of pores of 5 to 15%.
Preferably, the shape of the holes of the microporous metal foil is not particularly limited, and may be one or more selected from circular holes, rectangular holes, rhombic holes, elliptical holes and triangular holes, and may also be holes of other shapes.
Preferably, the active material layer includes an active material, a conductive agent, and a binder.
Preferably, the active material includes graphite, hard carbon, soft carbon, nano-silicon, alloy silicon, silica and mixtures thereof.
Preferably, the active material is a mixture of graphite and Si, or a mixture of graphite and SiOx.
Preferably, the surface density of the active material layer is 8 to 20mg/cm2。
Preferably, the lithium supplement layer is a lithium foil or a lithium alloy foil, and the thickness of the lithium supplement layer is 1-20 μm.
The lithium supplement layer is too thick, so that on one hand, the thickness of a lithium ion battery cell is increased, and the volume energy density of the battery is reduced; on the other hand, if lithium in the lithium supplement layer enters the negative electrode active material layer in an excessive amount relatively quickly, lithium ions desorbed from the positive electrode are prevented from being inserted into the negative electrode, and lithium ion deposition of the lithium ion battery is caused, thereby deteriorating the cycle performance and safety performance of the battery. However, if the lithium is not supplemented by the lithium supplementing layer, the first coulombic efficiency of the lithium ion battery is not high, and the loss of active lithium is caused, so that the gram capacity of the battery is low, and the energy density and the cycle performance of the battery are reduced. Therefore, the thickness of the lithium supplement layer needs to be reasonably controlled.
Preferably, the microporous metal foil is any one of a copper foil, a nickel foil, a titanium foil, a silver foil, a nickel-copper alloy foil, an aluminum-zirconium alloy foil, a stainless steel foil, a plastic substrate surface copper-plated foil, and a plastic substrate surface nickel-plated foil.
Additionally, the utility model provides a lithium ion battery, including positive plate, the above any kind of negative pole piece, set up in diaphragm between positive plate and the negative pole piece to and electrolyte.
Furthermore, the utility model also provides a preparation method of above-mentioned negative pole piece and lithium ion battery.
The preparation method of the negative plate comprises the following steps:
the method comprises the following steps: and (2) laminating the lithium supplement layer and the microporous metal foil (a piece of microporous metal foil is laminated on both sides of the lithium supplement layer) in a drying room (the dew point is below-35 ℃), preparing an active substance layer by using a dry process, and bonding the active substance layer and the microporous metal foil together after drying.
The second method comprises the following steps: and pressing the lithium supplement layer and the microporous metal foil in a drying room (the dew point is lower than-35 ℃). And then preparing negative electrode oily slurry, coating the negative electrode oily slurry on the microporous metal foil in a drying room, and drying.
The third method comprises the following steps: preparing cathode slurry, coating the cathode slurry on one surface of the microporous metal foil, and drying to obtain the microporous metal foil with one coated surface. And respectively laminating two microporous metal foils coated on one side on two sides of the lithium supplement layer in a drying room (dew point < -35 ℃).
The method four comprises the following steps: and preparing an active substance layer by using a dry process, laminating the active substance layer with the microporous metal foil, and drying to obtain the microporous metal foil with a single-side coating. And respectively laminating two microporous metal foils coated on one side on two sides of the lithium supplement layer in a drying room (dew point < -35 ℃).
And after the negative plate is prepared, the negative plate, the positive plate and the diaphragm are wound or laminated to prepare a battery core, and the lithium ion battery containing the negative plate is obtained after liquid injection and activation.
The utility model provides a lithium ion battery's preparation method makes and mends lithium layer and micropore metal forming through pressfitting processing and contacts together, and simple process realizes easily, compares with current lithium ion battery technology, need not to increase extra process, can effectively save resource and energy, and does not influence the energy consumption, is fit for large-scale production.
The beneficial effects of the utility model reside in that:
1. the lithium supplement layer may be in contact with the active material layer through the micropores, and lithium supplement to the negative electrode active material layer is achieved in the presence of the electrolyte. By supplementing lithium, the capacity of the battery can be improved, and the energy density of the battery is improved. In addition, lithium supplement can also reduce the loss of active lithium, thereby prolonging the cycle life of the battery.
2. Because lithium is supplemented through micropore contact, the control of lithium supplementing speed can be realized to a certain extent by controlling the number of micropores and the aperture of the micropores, so that the controllable lithium supplementing is realized.
Drawings
Fig. 1 is a schematic structural diagram of a negative plate of the present invention;
101-lithium supplement layer, 102-microporous metal foil and 103-active material layer.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the present application will be clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The utility model provides a negative pole piece, including mending lithium layer 101, micropore metal forming 102 to and active substance layer 103, mend lithium layer 101, micropore metal forming 102 and active substance layer 103 and laminate together according to the order of "active substance layer 103/micropore metal forming 102/mend lithium layer 101/micropore metal forming 102/active substance layer 103".
Preferably, the microporous metal foil 102 has a thickness of 2-10 μm.
Preferably, the microporous metal foil 102 has a thickness of 4-6 μm.
Preferably, the pore size of the microporous metal foil 102 is 0.1 to 5 μm.
Preferably, the pore size of the microporous metal foil 102 is 0.5 to 1 μm.
Preferably, the microporous metal foil 102 has an areal density of pores of 0.1 to 30%.
Preferably, the microporous metal foil 102 has an areal density of pores of 5-15%.
Preferably, the shape of the holes of the microporous metal foil 102 is not particularly limited, and may be selected from one or more of circular holes, rectangular holes, rhombic holes, elliptical holes, triangular holes, and other shapes of holes.
Preferably, the active material layer 103 includes an active material, a conductive agent, and a binder.
Preferably, the active material includes graphite, hard carbon, soft carbon, nano-silicon, alloy silicon, silica and mixtures thereof.
Preferably, the active material is a mixture of graphite and Si, or a mixture of graphite and SiOx.
Preferably, the active material layer 103 has an areal density of 8 to 20mg/cm2。
Preferably, the lithium supplement layer 101 is a lithium foil or a lithium alloy foil, and the thickness of the lithium supplement layer 101 is 1 to 20 μm.
Preferably, the microporous metal foil 102 is any one of a copper foil, a nickel foil, a titanium foil, a silver foil, a nickel-copper alloy foil, an aluminum-zirconium alloy foil, a stainless steel foil, a plastic substrate surface-plated copper foil, and a plastic substrate surface-plated nickel foil.
Additionally, the utility model provides a lithium ion battery, including positive plate, any kind of negative pole piece of above sets up the diaphragm between positive plate and negative pole piece to and electrolyte.
Furthermore, the utility model also provides a preparation method of above-mentioned negative pole piece and lithium ion battery.
The preparation method of the negative plate comprises the following steps:
the method comprises the following steps: in a drying room (dew point is minus 35 ℃), a lithium supplement layer 101 and a microporous metal foil 102 are pressed (a piece of microporous metal foil 102 is pressed on both sides of the lithium supplement layer 101), an active material layer 103 is prepared by a dry process, and the active material layer 103 and the microporous metal foil 102 are bonded together after drying.
The second method comprises the following steps: and (3) laminating the lithium supplement layer 101 and the microporous metal foil 102 in a drying room (dew point < -35 ℃). And then preparing the negative electrode oily slurry, coating the negative electrode oily slurry on the microporous metal foil 102 in a drying room, and drying.
The third method comprises the following steps: the method comprises the steps of preparing cathode slurry, coating the cathode slurry on one surface of the microporous metal foil 102, and drying to obtain the microporous metal foil 102 with one coated surface. Two pieces of microporous metal foils 102 coated on one side are respectively pressed on two sides of a lithium supplement layer 101 in a drying room (dew point < -35 ℃).
The method four comprises the following steps: and preparing an active material layer 103 by using a dry process, laminating the active material layer with the microporous metal foil 102, and drying to obtain the microporous metal foil 102 with a single-side coating. Two pieces of microporous metal foils 102 coated on one side are respectively pressed on two sides of a lithium supplement layer 101 in a drying room (dew point < -35 ℃).
And after the negative plate is prepared, the negative plate, the positive plate and the diaphragm are wound or laminated to prepare a battery core, and the lithium ion battery containing the negative plate is obtained after liquid injection and activation.
Example 1
The microporous metal copper foil with the thickness of 6 microns is selected as a current collector, the aperture of each micropore is 0.5-0.8 micron, and the area density of each pore is 15 percent (the area density of each pore is the proportion of the pore area to the total area of the metal foil).
Mixing the graphite + 10% SiOx mixed negative electrode, a conductive agent and a binder, and coating the mixture on one side of the copper foil, wherein the coating surface density is 9mg/cm2And obtaining the microporous copper foil coated with the active substance on one side.
And (3) in a drying room, laminating two pieces of microporous copper foil with an active material layer and lithium metal with the thickness of 10 mu m into a sandwich structure (the lithium metal is arranged on the side of the microporous copper foil far away from the active material layer), thus obtaining the negative plate.
And (4) making the negative plate, the LCO positive electrode and the diaphragm into a roll core, and injecting and forming to obtain the battery.
Example 2
The microporous metal copper foil with the thickness of 6 mu m is selected as a current collector, the aperture of each micropore is 0.5-0.8 mu m, and the area density of each micropore is 5%.
The rest is the same as in example 1.
Example 3
The microporous metal copper foil with the thickness of 6 mu m is selected as a current collector, the aperture of each micropore is 0.5-0.8 mu m, and the area density of each micropore is 30%.
The rest is the same as in example 1.
Example 4
The method comprises the following steps of selecting a microporous metal copper foil with the thickness of 6 mu m as a current collector, wherein the aperture of each micropore is 4-5 mu m, and the areal density of each pore is 30%.
The rest is the same as in example 1.
Example 5
The microporous metal copper foil with the thickness of 6 mu m is selected as a current collector, the aperture of each micropore is 0.1-0.3 mu m, and the areal density of each micropore is 30%.
The rest is the same as in example 1.
Example 6
The method comprises the following steps of selecting a microporous metal copper foil with the thickness of 6 mu m as a current collector, wherein the aperture of each micropore is 4-5 mu m, and the areal density of each pore is 5%.
The rest is the same as in example 1.
Comparative example 1
Selecting a copper foil with the thickness of 6 mu m as a current collector, coating the same negative electrode slurry as in example 1 on two sides of the current collector, wherein the coating surface density is 5mg/cm2I.e., the first slurry layer, and then drying the pole piece.
And arranging a lithium foil layer on the first slurry layer in the drying room, wherein the thickness of the lithium foil layer is 5 mu m. Then coating a second slurry layer (the composition of the second slurry layer is the same as that of the first slurry layer) on the surface of the lithium foil, wherein the surface density of the second slurry layer is 4mg/cm2。
And drying to obtain the lithium-supplementing negative plate with the lithium foil arranged in the active material layer.
The rest is the same as in example 1.
Comparative example 2
The microporous metal copper foil with the thickness of 6 mu m is selected as a current collector, the aperture of each micropore is 0.5-0.8 mu m, and the areal density of each micropore is 1%.
The rest is the same as in example 1.
The lithium ion batteries manufactured in examples 1 to 6 and comparative examples 1 and 2 were subjected to test experiments, respectively, and the test results are shown in table 1.
TABLE 1 lithium ion Battery Performance test results
As can be seen from the data in table 1, the first effect of comparative example 1 is very high, almost identical to that of lithium cobaltate, but the cycle life is poor because the rate of lithium supplement is not controlled, lithium in the lithium foil completely enters into the negative electrode before formation, so that the first effect is very high, but during the subsequent charge and discharge cycles, the cycle performance is poor because the amount of lithium supplement is too much, so that the lithium is separated out in the early cycle.
As can be seen from the comparison between the example and the comparative example 2, the comparative example 2 has a small pore size (1%), so the lithium replenishing speed is slow, the first effect of the battery is low, the gram-weight capacity is not high, and the energy density of the battery is not advantageous. But the number of cycles is high because it can slowly release lithium into the negative active material to replenish active lithium consumed during the cycle.
To sum up the analysis, the utility model discloses can control the benefit lithium speed through aperture and the aperture area of control micropore metal forming, through setting up suitable aperture and aperture area, can obtain the optimal comprehensive properties.
The above examples are described only for the ratio of 10% SiOx in the active material layer, and the aperture area can be set specifically according to the kind and the content of silicon.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A negative electrode sheet is characterized by comprising a lithium supplement layer, a microporous metal foil and an active material layer,
the lithium supplement layer, the microporous metal foil, and the active material layer are laminated in the order of active material layer/microporous metal foil/lithium supplement layer/microporous metal foil/active material layer.
2. Negative electrode sheet according to claim 1, characterized in that the thickness of the microporous metal foil is 2-10 μm.
3. Negative electrode sheet according to claim 2, characterized in that the thickness of the microporous metal foil is 4-6 μm.
4. Negative electrode sheet according to claim 1, characterized in that the pore size of the microporous metal foil is 0.1-5 μm.
5. Negative electrode sheet according to claim 4, characterized in that the pore size of the microporous metal foil is 0.5-1 μm.
6. Negative electrode sheet according to claim 1, characterized in that the microporous metal foil has an areal density of pores of 0.1-30%.
7. Negative electrode sheet according to claim 6, characterized in that the microporous metal foil has an areal density of pores of 5-15%.
8. The negative electrode sheet according to claim 1, wherein said lithium-supplementing layer is a lithium foil or a lithium alloy foil,
the thickness of the lithium supplement layer is 1-20 μm.
9. The negative electrode sheet according to claim 1, wherein the microporous metal foil is any one of a copper foil, a nickel foil, a titanium foil, a silver foil, a nickel-copper alloy foil, an aluminum-zirconium alloy foil, a stainless steel foil, a plastic substrate surface copper-plated foil, and a plastic substrate surface nickel-plated foil.
10. A lithium ion battery is characterized by comprising a positive plate, a negative plate, a diaphragm arranged between the positive plate and the negative plate, and electrolyte;
the negative electrode sheet according to any one of claims 1 to 9.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121434271.XU CN214848691U (en) | 2021-06-24 | 2021-06-24 | Negative plate and lithium ion battery comprising same |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121434271.XU CN214848691U (en) | 2021-06-24 | 2021-06-24 | Negative plate and lithium ion battery comprising same |
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| CN214848691U true CN214848691U (en) | 2021-11-23 |
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