CN114512633B - Negative plate and battery comprising same - Google Patents
Negative plate and battery comprising same Download PDFInfo
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- CN114512633B CN114512633B CN202210039435.1A CN202210039435A CN114512633B CN 114512633 B CN114512633 B CN 114512633B CN 202210039435 A CN202210039435 A CN 202210039435A CN 114512633 B CN114512633 B CN 114512633B
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 18
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Abstract
The invention provides a negative electrode plate and a battery comprising the negative electrode plate, wherein the negative electrode plate comprises a negative electrode current collector, an electrolyte storage layer and a negative electrode active material layer; the electrolyte storage layer adopts the filler with high specific surface area, and the filler with high specific surface area can store a large amount of electrolyte and supplement the deficiency of the electrolyte. The use of the negative plate simultaneously improves the rate capability and the energy density of the battery, and through electrochemical theory calculation, in the electrode plate, the potential of the negative plate close to the surface of the diaphragm is lower, the polarization and the electrolyte concentration are uneven, so that the utilization rate of the electrode plate is low, the lithium precipitation risk is higher, and the lithium precipitation risk is reduced, the utilization rate of the electrode plate is improved, and the energy density is improved by constructing an orientation hole rapid ion channel on the surface of the electrode plate.
Description
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a negative plate and a battery comprising the negative plate.
Background
At present, the requirements on the energy density and the quick charge performance of the lithium ion battery are higher and higher, and the thickness of a pole piece is required to be increased in order to improve the energy density of the battery, but the increase of the thickness of the pole piece can increase the migration path of electrolyte in the pole piece, and the increase of the migration path can lead to the reduction of the multiplying power performance of the pole piece. How to improve the fast charge performance on the premise of ensuring the energy density of the battery has become a factor restricting the development of the battery. The research shows that the migration path of the electrolyte can be reduced through the three-dimensional through hole, the transmission rate is improved, but under the condition of high-rate charging, the internal electrolyte of the through hole cannot be timely supplemented, and the problem of lithium precipitation can be generated.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a negative plate and a battery comprising the negative plate, wherein the negative plate can solve the problems that electrolyte near a through hole cannot be supplemented and lithium precipitation can be generated under a high-rate condition, the rate performance and the energy density of the battery comprising the negative plate are obviously improved, and the cycle performance of the battery is improved.
The invention aims at realizing the following technical scheme:
A negative electrode sheet including a negative electrode current collector, an electrolyte storage layer, and a negative electrode active material layer; the electrolyte storage layer is positioned on one side or two side surfaces of the negative electrode current collector, and the negative electrode active material layer is positioned on the surface of the electrolyte storage layer;
the electrolyte storage layer includes a filler;
The anode active material layer is provided with first orientation holes.
According to the embodiment of the invention, the specific surface area S of the filler is more than or equal to 45m 2/g.
According to the embodiment of the invention, the first orientation hole is constructed on the anode active material layer, and can be used as a rapid ion channel for ions (such as lithium ions) to pass through rapidly in the charge and discharge process, so that the problems of lithium precipitation and the like on the surface of the anode sheet caused by polarization and uneven concentration of electrolyte are solved; meanwhile, the rate capability and the energy density of the battery can be improved, and further, the electrolyte storage layer is arranged between the anode active material layer and the anode current collector, so that the electrolyte storage layer can provide the consumed electrolyte, and the problem of lithium precipitation around the pore canal is solved.
Further research shows that the specific surface area of the filler in the electrolyte storage layer can influence the improvement of concentration polarization near the orientation holes, the different specific surface areas have different requirements on Li + diffusion capacity, and when the specific surface area S of the filler is more than or equal to 45m 2/g, the rate performance and the energy density of the battery can be obviously improved. When the specific surface area S of the filler is less than 45m 2/g, the stored electrolyte is insufficient to compensate the consumed electrolyte, and the problem of lithium precipitation around the pore canal cannot be improved.
According to an embodiment of the invention, the median particle diameter Dv50 of the filler is ∈2 μm, preferably from 0.1 μm to 2 μm, for example 0.1μm、0.2μm、0.3μm、0.4μm、0.5μm、0.6μm、0.7μm、0.8μm、0.9μm、1.0μm、1.1μm、1.2μm、1.3μm、1.4μm、1.5μm、1.6μm、1.7μm、1.8μm、1.9μm or 2 μm.
According to an embodiment of the present invention, the filler is at least one selected from the group consisting of alumina, zirconia, yttria, and barium oxide.
According to an embodiment of the present invention, the volume percentage of the first alignment hole is 1vol% to 50vol% based on the total volume of the anode active material layer. Illustratively, the volume percentage of the volume of the first oriented pores to the total volume of the anode active material layer is 1vol％、2vol％、5vol％、8vol％、10vol％、12vol％、15vol％、18vol％、20vol％、25vol％、30vol％、35vol％、40vol％、45vol％、50vol％ or any point value in the range consisting of the above two-point values.
According to an embodiment of the invention, the radius R of the first oriented holes is 5 μm to 150 μm, preferably 10 μm to 70 μm. Illustratively, the radius R of the first oriented pores is 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or any point value in the range of two-point values.
According to an embodiment of the present invention, the thickness H of the anode active material layer is 10 μm to 200 μm, preferably 20 μm to 100 μm. Illustratively, the thickness H of the anode active material layer is 10μm、15μm、20μm、30μm、40μm、50μm、60μm、70μm、80μm、90μm、100μm、110μm、120μm、130μm、140μm、150μm、160μm、170μm、180μm、190μm、200μm or any point value in the range of the above two-point values.
According to an embodiment of the present invention, the negative electrode active material layer has a compacted density of 1.4 to 1.85g/m 3.
According to an embodiment of the present invention, the thickness h of the electrolyte storage layer is 0.5 μm to 10 μm, preferably 1 μm to 3 μm. Illustratively, the electrolyte storage layer has a thickness h of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any point value in the range of two-point values.
According to an embodiment of the present invention, the first orientation hole is a through hole or a non-through hole, and the through hole means that the first orientation hole penetrates through the anode active material layer, that is, the hole depth of the first orientation hole is equal to the thickness of the anode active material layer; the non-penetrating hole means that the first alignment hole does not penetrate the anode active material layer, i.e., the hole depth of the first alignment hole is smaller than the thickness of the anode active material layer.
According to an embodiment of the present invention, the median particle diameter Dv50 of the negative electrode active material is 1 μm to 30 μm. Illustratively, the median particle diameter Dv50 of the negative electrode active material is 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm,5 μm,6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 26 μm, 28 μm, 30 μm or any point value in the range of two-point values.
According to an embodiment of the present invention, the negative electrode sheet further includes a second orientation hole provided on the electrolyte storage layer.
According to the embodiment of the invention, the second orientation hole is constructed on the electrolyte storage layer, and under the condition of sufficient electrolyte, the electrolyte storage layer can also be used as a rapid ion channel for ions (such as lithium ions) to pass through rapidly in the charge and discharge process, so that the problems of lithium precipitation on the surface of the negative electrode plate and the like caused by polarization and uneven concentration of the electrolyte are solved; and meanwhile, the rate capability and the energy density of the battery can be improved.
According to an embodiment of the present invention, the volume of the second oriented pores is 1 to 50vol% based on the total volume of the electrolyte storage layer. Illustratively, the volume percentage of the volume of the second oriented pores to the total volume of the electrolyte storage layer is 1vol％、2vol％、5vol％、8vol％、10vol％、12vol％、15vol％、18vol％、20vol％、25vol％、30vol％、35vol％、40vol％、45vol％、50vol％ or any point value in the range of two-point values.
According to an embodiment of the invention, the radius r of the second oriented holes is 5 μm to 150 μm, preferably 10 μm to 70 μm. Illustratively, the radius r of the second oriented pores is 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or any point value in the range of two-point values.
According to an embodiment of the present invention, the second orientation hole is a through hole or a non-through hole, and the through hole refers to that the second orientation hole penetrates through the electrolyte storage layer, that is, the hole depth of the second orientation hole is equal to the thickness of the electrolyte storage layer; the non-penetrating holes means that the second oriented holes do not penetrate through the electrolyte storage layer, i.e., the hole depth of the second oriented holes is smaller than the thickness of the electrolyte storage layer.
According to an embodiment of the present invention, the negative electrode tab further includes a third orientation hole provided on the negative electrode current collector.
According to the embodiment of the invention, the third orientation hole is constructed on the negative electrode current collector, and the third orientation hole can also be used as a rapid ion channel for ions (such as lithium ions) to pass through rapidly in the charge and discharge process, so that the problems of lithium precipitation on the surface of the negative electrode plate and the like caused by polarization and uneven concentration of electrolyte are solved; and meanwhile, the rate capability and the energy density of the battery can be improved.
According to an embodiment of the present invention, the volume of the third oriented pores is 1vol% to 50vol% of the total volume of the anode current collector. Illustratively, the volume percent of the volume of the third oriented pores to the total volume of the negative current collector is 1vol％、2vol％、5vol％、8vol％、10vol％、12vol％、15vol％、18vol％、20vol％、25vol％、30vol％、35vol％、40vol％、45vol％、50vol％ or any point value in the range of two-point values described above.
According to an embodiment of the invention, the radius L of the third oriented holes is 5 μm to 150 μm, preferably 10 μm to 70 μm. Illustratively, the radius L of the third oriented pores is 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or any point value in the range of two-point values.
According to an embodiment of the present invention, the third orientation hole is a through hole or a non-through hole, and the through hole refers to that the third orientation hole penetrates through the negative current collector, that is, the hole depth of the third orientation hole is equal to the thickness of the negative current collector; the non-penetrating hole means that the third orientation hole does not penetrate through the negative electrode current collector, i.e., the hole depth of the third orientation hole is smaller than the thickness of the negative electrode current collector.
According to an embodiment of the present invention, the method for constructing the first orientation hole and the second orientation hole includes, but is not limited to, at least one of a template method, a volatile agent pore-forming method, a laser punching method, a nail plate rolling method, and the like.
According to an embodiment of the present invention, the method for constructing the third orientation hole includes, but is not limited to, at least one of a laser punching method, a nail plate rolling method, and the like.
According to an embodiment of the present invention, the arrangement position of the second orientation hole is preferably the same as the arrangement position of the first orientation hole. That is, alignment holes are formed in the anode active material layer and the electrolyte storage layer on the surface of the anode current collector, and first alignment holes are formed in the anode active material layer and second alignment holes are formed in the electrolyte storage layer, respectively.
According to an embodiment of the present invention, the arrangement position of the third orientation hole and the arrangement position of the second orientation hole are the same as the arrangement position of the first orientation hole. That is, alignment holes are formed in the negative electrode sheet, first alignment holes are formed in the negative electrode active material layer, second alignment holes are formed in the electrolyte solution storage layer, and third alignment holes are formed in the negative electrode current collector.
According to an embodiment of the present invention, the negative electrode current collector is selected from copper foil or carbon coated copper foil.
According to an embodiment of the present invention, the negative electrode current collector has a thickness of 5 μm to 20 μm.
According to an embodiment of the present invention, the anode active material layer includes an anode active material, a conductive agent, and a binder.
According to an embodiment of the present invention, the mass percentage of each component in the anode active material layer is: 90 to 99.2 weight percent of negative electrode active material, 0.2 to 4 weight percent of conductive agent and 0.6 to 6 weight percent of binder.
According to an embodiment of the present invention, the conductive agent is at least one selected from conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, and metal powder.
According to an embodiment of the present invention, the binder is at least one selected from the group consisting of polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.
According to an embodiment of the present invention, the negative electrode active material is at least one selected from SiOx (0 < x < 2), lithium-containing transition metal oxide, tin-based composite oxide, artificial graphite, natural graphite, hard carbon, soft carbon, mesophase microspheres, fullerenes, graphene.
According to an embodiment of the present invention, the surface density of the negative electrode sheet is 0.003 to 0.015g/cm 2.
The invention also provides a preparation method of the negative plate, which comprises the following steps:
1) Respectively preparing slurry for forming a negative electrode active material layer and slurry for forming an electrolyte storage layer;
2) Coating slurry for forming an electrolyte storage layer on one side or two side surfaces of the negative electrode current collector along the length direction of the negative electrode current collector to form the electrolyte storage layer; coating the slurry for forming the anode active material layer on the surface of the electrolyte storage layer to form the anode active material layer; and rolling, slitting and pore-forming to obtain the negative electrode plate.
According to an embodiment of the present invention, in step 1), the solid content of the slurry for forming the anode active material layer is 40 to 50wt%. The viscosity of the slurry for forming the negative electrode active material layer is 2000-5000 mPas.
According to an embodiment of the present invention, in step 1), the solid content of the slurry for forming the electrolyte storage layer is 40 to 50wt%. The viscosity of the slurry for forming the electrolyte storage layer is 2000-5000 mPas.
The invention also provides a battery, which comprises the negative plate.
According to an embodiment of the invention, the battery has a winding or lamination structure.
According to an embodiment of the invention, the battery is a lithium ion battery.
The invention has the beneficial effects that:
The invention provides the negative electrode plate and the battery comprising the negative electrode plate, and the invention can reduce the lithium precipitation risk, improve the utilization rate of the electrode plate and improve the energy density by constructing the orientation hole rapid ion channel on the surface of the electrode plate. Furthermore, the surface of the negative electrode plate further comprises an electrolyte storage layer, the electrolyte storage layer adopts a filler with high specific surface area, and a large amount of electrolyte can be stored in the filler with high specific surface area, so that the defects of the electrolyte are overcome, and the problems of low utilization rate of the electrode plate, larger lithium precipitation risk and the like caused by uneven polarization and electrolyte concentration are avoided. Further research shows that the specific surface area of the filler in the electrolyte storage layer can influence the improvement of concentration polarization near the orientation holes, the different specific surface areas have different requirements on Li + diffusion capacity, and when the specific surface area S of the filler is more than or equal to 45m 2/g, the rate performance and the energy density of the battery can be obviously improved.
Drawings
Fig. 1 is a schematic structural diagram of a negative electrode sheet according to embodiment 1 of the present invention.
Fig. 2 is a schematic structural view of a negative electrode sheet according to a preferred embodiment of the present invention.
Fig. 3 is a schematic structural view of a negative electrode sheet according to a preferred embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention. All techniques implemented based on the above description of the invention are intended to be included within the scope of the invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the examples described below are commercially available unless otherwise specified.
Example 1
80Wt% of alumina particles with the specific surface area of 55m 2/g and the particle diameter Dv50 of 1 mu m, 5wt% of conductive carbon black and 15wt% of polyvinylidene fluoride are mixed, and N-methyl pyrrolidone is added to be stirred and dispersed to prepare slurry, namely electrolyte storage layer slurry.
Preparing negative electrode slurry by taking graphite as a negative electrode active material: according to the mass ratio of 96.8% of anode active material, 1.2% of conductive agent (conductive carbon black) and 2% of binder (styrene-butadiene rubber), mixing and stirring to obtain anode active material layer slurry, the viscosity of the slurry is 2000-5000 mPa.s, and the solid content is 40% -50%.
Coating electrolyte storage layer slurry and anode active material layer slurry on an anode current collector by using double-layer coating equipment, wherein the electrolyte storage layer is coated on the anode current collector, the anode active material layer is coated on the electrolyte storage layer, a cathode plate with the thickness of the electrolyte storage layer of 3 mu m and the thickness of the anode active material layer of 50 mu m is obtained after drying and rolling, a first orientation hole with the radius R of 25 mu m is constructed on the anode active material layer by adopting a pulse laser pore-forming method, and the volume of the first orientation hole accounts for 20-25 vol% of the total volume of the anode active material layer. And the first orientation hole is a through hole, that is, the hole depth of the first orientation hole is equal to the thickness of the anode active material layer, and the specific structure is shown in fig. 1.
Preparing positive electrode slurry from a positive electrode active material: mixing 96% of positive electrode active material (lithium cobaltate), 2.5% of conductive agent (conductive carbon black) and 1.5% of binder (PVDF) with NMP according to the mass ratio, and stirring to obtain the positive electrode slurry, wherein the viscosity of the slurry is 2000-7000 mPa.s, and the solid content is 70-80%. And (3) coating the positive electrode slurry on the surfaces of two sides of the positive electrode current collector after passing through a screen, and drying and rolling to obtain the positive electrode plate.
Rolling, die cutting and cutting the positive and negative electrode sheets, winding and assembling the positive and negative electrode sheets into a winding core, packaging the winding core by an aluminum plastic film after the short circuit test is qualified, baking the winding core in an oven to remove water until the water content reaches the water content standard required by liquid injection, injecting electrolyte, aging the winding core for 24-48 hours, and completing primary charging by a hot-press formation process to obtain the activated battery core.
Examples 2 to 7
Other operations are the same as in example 1, except that: the thickness h of the electrolyte storage layer, the specific surface area S of the filler and the radius R of the first orientation hole after drying and rolling are different, and are shown in table 1.
Comparative example 1
Other operations are the same as in example 1, except that: and (3) drying and rolling to obtain a negative plate with the electrolyte storage layer thickness of 3 mu m and the negative active material layer thickness of 50 mu m without pore-forming treatment, and assembling the negative plate into the lithium ion battery.
Comparative example 2
Other operations are the same as in example 1, except that: the method comprises the steps of coating the slurry of the anode active material layer on the anode current collector by using coating equipment without pore-forming treatment and without an electrolyte storage layer, wherein the anode active material layer is coated on the anode current collector, drying and rolling to obtain an anode sheet with the anode active material layer thickness of 50 mu m, and assembling the anode sheet into a lithium ion battery.
Comparative example 3
Other operations are the same as in example 1, except that: and the anode active material layer slurry is coated on the anode current collector by using coating equipment without an electrolyte storage layer, wherein the anode active material layer is coated on the anode current collector, and a cathode plate with the thickness of the anode active material layer of 50 mu m is obtained after drying and rolling, and is assembled into a lithium ion battery after pore forming.
The cells prepared in the above examples and comparative examples were charged at a 0.5C rate, and the ratio of the energy E discharged at 0.5C rate to the cell volume V was the energy density ED/Wh.L -1.
The cells prepared in the above examples and comparative examples were charged at 3C rate, discharged at 1C rate, and subjected to cycle life test 700 times to test the capacity retention rate of the cells.
The battery cells prepared in the examples and the comparative examples are charged at a 5C rate, discharged at a 0.5C rate, and the dissected battery cells check the lithium precipitation condition of the surface of the negative electrode after 20 charge and discharge cycles.
Table 1 results of performance tests of lithium ion batteries of examples and comparative examples
The above results show that the negative electrode plate prepared according to the invention improves the rate capability and energy density of the battery compared with the negative electrode plate prepared in a conventional manner, and can effectively solve the problems of low utilization rate and surface lithium precipitation of the negative electrode plate of the battery with high energy density under the condition of quick charge.
Specifically, the negative electrode sheet of example 1 solves the problems of battery cell lithium precipitation and cycle retention rate compared with comparative example 1; compared with comparative example 2, the energy density is improved on the premise of ensuring that lithium is not separated out; comparative example 3 demonstrates the improvement in the cell lithium-eluting performance of the electrolyte storage layer as compared to example 1 in pore negative electrode lithium-eluting.
On the basis of example 1, examples 2 to 7 were each optimized for energy density and cycle retention; further research has found that when the electrolyte storage layer is too thick (as in example 6), the energy density loss to the pole piece is great, and the pole piece is polarized greatly due to insufficient conductivity; when the specific surface area of the filler is too low (e.g., example 7), the problems of cell lithium precipitation and energy density elevation cannot be significantly improved.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A negative electrode sheet, characterized in that the negative electrode sheet comprises a negative electrode current collector, an electrolyte storage layer, and a negative electrode active material layer; the electrolyte storage layer is positioned on one side or two side surfaces of the negative electrode current collector, and the negative electrode active material layer is positioned on the surface of the electrolyte storage layer;
the electrolyte storage layer includes a filler;
The anode active material layer is provided with first orientation holes;
the specific surface area S of the filler is more than or equal to 45m 2/g;
The median particle diameter Dv50 of the filler is 0.4-2 mu m;
the radius R of the first orientation hole is 5-150 mu m; the volume of the first orientation holes accounts for 1-50vol% of the total volume of the anode active material layer;
the thickness H of the negative electrode active material layer is 10-200 mu m; the thickness h of the electrolyte storage layer is 0.5-10 mu m.
2. The negative electrode sheet according to claim 1, wherein the filler is at least one selected from the group consisting of alumina, zirconia, yttria, and barium oxide.
3. The negative electrode sheet according to any one of claims 1 to 2, further comprising a second orientation hole provided on the electrolyte storage layer.
4. The negative electrode sheet according to claim 3, wherein the volume of the second orientation holes is 1vol% to 50vol% of the total volume of the electrolyte storage layer;
and/or the radius r of the second orientation hole is 5-150 μm.
5. The negative electrode sheet according to any one of claims 1-2, further comprising a third orientation hole provided on a negative electrode current collector.
6. The negative electrode sheet according to claim 5, wherein the volume of the third orientation hole is 1vol% to 50vol% of the total volume of the negative electrode current collector;
and/or the radius L of the third orientation hole is 5-150 mu m.
7. The negative electrode sheet according to any one of claims 1 to 2, wherein the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder;
And/or, the mass percentage of each component in the anode active material layer is as follows: 90 to 99.2 wt% of a negative electrode active material, 0.2 to 4 wt% of a conductive agent, and 0.6 to 6 wt% of a binder.
8. A battery comprising the negative electrode sheet of any one of claims 1-7.
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| CN202210039435.1A CN114512633B (en) | 2022-01-13 | Negative plate and battery comprising same |
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| CN202210039435.1A CN114512633B (en) | 2022-01-13 | Negative plate and battery comprising same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102332556A (en) * | 2010-09-15 | 2012-01-25 | 东莞新能源科技有限公司 | Lithium ion secondary cell and cathode thereof |
| CN111742385A (en) * | 2018-02-22 | 2020-10-02 | Jm能源株式会社 | Power storage device, negative electrode for power storage device, and methods for producing same |
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102332556A (en) * | 2010-09-15 | 2012-01-25 | 东莞新能源科技有限公司 | Lithium ion secondary cell and cathode thereof |
| CN111742385A (en) * | 2018-02-22 | 2020-10-02 | Jm能源株式会社 | Power storage device, negative electrode for power storage device, and methods for producing same |
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