CN114335424A - Negative plate, battery and electronic equipment - Google Patents
Negative plate, battery and electronic equipment Download PDFInfo
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- CN114335424A CN114335424A CN202111669708.2A CN202111669708A CN114335424A CN 114335424 A CN114335424 A CN 114335424A CN 202111669708 A CN202111669708 A CN 202111669708A CN 114335424 A CN114335424 A CN 114335424A
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- 239000011248 coating agent Substances 0.000 claims abstract description 137
- 238000000576 coating method Methods 0.000 claims abstract description 137
- 239000011149 active material Substances 0.000 claims abstract description 94
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 55
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 55
- 239000010439 graphite Substances 0.000 claims abstract description 54
- 239000002210 silicon-based material Substances 0.000 claims abstract description 32
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 39
- 229910052710 silicon Inorganic materials 0.000 claims description 39
- 239000010703 silicon Substances 0.000 claims description 39
- 239000011247 coating layer Substances 0.000 claims description 35
- 239000007770 graphite material Substances 0.000 claims 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 31
- 229910052744 lithium Inorganic materials 0.000 abstract description 31
- 230000008021 deposition Effects 0.000 abstract description 11
- 239000010410 layer Substances 0.000 description 46
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 32
- 239000000463 material Substances 0.000 description 22
- 239000000377 silicon dioxide Substances 0.000 description 16
- 239000000126 substance Substances 0.000 description 15
- 239000013543 active substance Substances 0.000 description 14
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 8
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 8
- 239000011889 copper foil Substances 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 4
- 239000003575 carbonaceous material Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000003795 desorption Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The application provides a negative pole piece, battery and electronic equipment, the negative pole piece includes mass flow body, utmost point ear, first coating and second coating, the one end of mass flow body is equipped with the utmost point ear, the utmost point ear is followed the first direction extension of mass flow body, the surface coating of at least one side of mass flow body has the first coating, the second coating coat in the surface of first coating; the first coating comprises a first active material, and the first active material comprises graphite and a silicon-based material; along the first direction, the second coating comprises a first area and a second area, the first area is an area, close to the tab, in the second coating, the first area of the second coating comprises a second active material, the second active material is graphite, the second area of the second coating comprises a third active material, and the third active material comprises graphite and a silicon-based material. The lithium deposition of the negative plate can be reduced.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a negative plate, a battery and electronic equipment.
Background
The lithium ion battery has the advantages of high energy density, no memory effect, long service life and the like, and is widely applied to the fields of smart phones, notebook computers, Bluetooth, wearable equipment and the like. The lithium ion battery mainly depends on lithium ions to move between a positive electrode and a negative electrode to work, the energy density of the lithium ion battery is improved by doping a part of silicon-based material in negative electrode piece graphite in the conventional lithium ion battery, the current density near a tab is high in the circulation process of a negative electrode piece, and the conductivity of the silicon-based material is poor, so that the lithium is easy to separate out from the negative electrode piece.
Disclosure of Invention
The application provides a negative plate, a battery and an electronic device, which aim to solve the problem that lithium is easily separated from the negative plate.
In a first aspect, an embodiment of the present application provides a negative electrode plate, including a current collector, a tab, a first coating and a second coating, where the tab is disposed at one end of the current collector, the tab extends along a first direction of the current collector, the first coating is coated on a surface of at least one side of the current collector, and the second coating is coated on a surface of the first coating;
along the first direction, the first coating comprises a first active material comprising graphite and a silicon-based material; the second coating comprises a first area and a second area, the first area is an area, close to the tab, in the second coating, the first area of the second coating comprises a second active material, the second active material is graphite, the second area of the second coating comprises a third active material, and the third active material comprises graphite and a silicon-based material.
In a second aspect, embodiments of the present application further provide a battery, where the battery includes the negative electrode sheet disclosed in the first aspect of the present application.
In a third aspect, an embodiment of the present application further provides an electronic device, where the electronic device includes the battery as disclosed in the second aspect of the present application.
In an embodiment of the present application, the second coating layer includes a first region and a second region, the first region and the second region are distributed along the first direction, the first region is a region near the tab in the second coating layer, the first coating layer includes a first active material, the first active material includes graphite and a silicon-based material, the first region of the second coating layer includes a second active material, the second active material is graphite, the second region of the second coating layer includes a third active material, and the third active material includes graphite and a silicon-based material. The first coating is less prone to lithium precipitation than the second coating, and the energy density can be improved by using a graphite doped silicon-based material as a first active material in the first coating; and the first region in the second coating is easier to analyze lithium than the second region, and graphite with better conductivity is used as a second active material in the first region close to the tab in the second coating, and a graphite blended silicon-based material is used as a third active material in the second region far away from the tab in the second coating, so that the energy density is improved, the lithium analysis is reduced, and the cycle performance of the negative plate is improved.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is one of schematic structural diagrams of a negative electrode sheet provided in an embodiment of the present application;
fig. 2 is a second schematic structural diagram of a negative electrode sheet provided in the embodiment of the present application;
fig. 3 is a third schematic structural diagram of a negative electrode sheet according to an embodiment of the present disclosure;
fig. 4 is a fourth schematic structural diagram of a negative electrode sheet provided in an embodiment of the present application;
fig. 5 is a fifth schematic structural view of a negative electrode sheet according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. 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 terms "first," "second," and the like in the embodiments of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Further, as used herein, "and/or" means at least one of the connected objects, e.g., a and/or B and/or C, means 7 cases including a alone, B alone, C alone, and both a and B present, B and C present, both a and C present, and A, B and C present.
Referring to fig. 1, fig. 1 is a schematic structural view of a negative electrode sheet provided in an embodiment of the present application, and as shown in fig. 1, the negative electrode sheet includes a current collector 10, a tab 20, a first coating 30 and a second coating 40, where one end of the current collector 10 is provided with the tab 20, the tab 20 extends along a first direction of the current collector 10, a surface of at least one side of the current collector 10 is coated with the first coating 30, and the second coating 40 is coated on a surface of the first coating 30;
the first coating 30 comprises a first active material comprising graphite and a silicon-based material; along the first direction, the second coating layer 40 includes a first region 41 and a second region 42, the first region 41 is a region of the second coating layer 40 near the tab 20, the first region 41 of the second coating layer 40 includes a second active material, the second active material is graphite, the second region of the second coating layer 40 includes a third active material, and the third active material includes graphite and a silicon-based material.
The first direction is a height direction of the negative electrode sheet, that is, an x-axis direction in fig. 1. The y-axis direction in fig. 1 is the thickness direction of the negative electrode sheet.
Specifically, the tab 20 may be formed by performing laser die cutting on the current collector 10, and a plurality of tabs 20 may be formed by performing laser die cutting on the current collector 10 to form a multi-stage tab negative plate, as shown in fig. 1, the tab 20 is formed by a protruding portion of the current collector 10. In the negative electrode sheet, on one hand, the potential of the region of the coating on the current collector 10 close to the current collector 10 is high, so that the lithium deposition is not easy to occur, that is, the first coating 30 is not easy to occur the lithium deposition than the second coating 40, and in order to improve the energy density of the negative electrode sheet, a silicon-based material may be doped into the first active material in the first coating 30 to replace part of graphite in the original first active material to improve the energy density of the negative electrode sheet; on the other hand, the current density of the area close to the tab 20 in the coating on the current collector 10 is relatively high, so that lithium deposition during high-rate charging can be avoided through the graphite coating, the current density of the area far from the tab 20 in the coating on the current collector 10 is relatively low, the energy density can be increased through the silicon-based material, that is, the second active material in the first area 41 can be composed of graphite, and the third active material in the second area 42 can include graphite and the silicon-based material.
In addition, since the silicon-based material has a large volume expansion during the charge and discharge processes, the use of the silicon-based material in the negative electrode sheet can be reduced and the volume expansion of the negative electrode sheet can be reduced by using graphite as the silicon-based material in the first region 41 of the second coating layer 40.
Optionally, as shown in fig. 1, a first length of the first region 41 in the first direction is smaller than a second length of the second region 42 in the first direction, and the first length is a length in a length range of 1 to 10 mm, and the second length is a length in a length range of 30 to 120 mm.
As shown in fig. 1, in the first direction, it can be understood that the height direction of the negative electrode tab in the figure is the direction in which the second active material in the second coating layer 40 is made of graphite, so that the region is prevented from emitting lithium during high-rate charging, the energy density can be increased by the silicon-based material in the third active material in the second region 42 while preventing lithium deposition, and the energy density can be further increased by the first length of the first region 41 in the first direction being smaller than the second length of the second region 42 in the first direction.
Optionally, the mass percentage of silicon in the first active material is greater than or equal to the mass percentage of silicon in the third active material.
Wherein the mass percentage of silicon refers to the percentage of the mass of silicon to the total mass of the coating substance (the sum of the masses of the active material and the inactive material). It is understood that the first coating layer 30 has a higher potential than the second coating layer 40 due to its proximity to the current collector 10, i.e., the second coating layer 40 is more susceptible to lithium desorption than the first coating layer 30, and the lithium phenomenon is slowly desorbed by reducing the mass percentage of silicon in the third active material in the second coating layer 40.
In this embodiment, the mass percent of silicon in the first active material is greater than or equal to the mass percent of silicon in the third active material, and lithium deposition of the second coating 40 is mitigated by the greater silicon content.
Optionally, the percentage by mass of silicon in the first active material is a percentage in the percentage range of 0.1% to 20%, and the percentage by mass of silicon in the third active material is a percentage in the percentage range of 0.1% to 10%.
As shown in fig. 1, since the second coating layer 40 near the current collector 10 has a higher potential in the thickness direction (y-axis direction) of the negative electrode sheet, lithium deposition is less likely to occur than in the first coating layer 30, and the mass percentage of silicon in the first active material of the first coating layer 30 may be greater than or equal to the mass percentage of silicon in the second active material of the second coating layer 40, thereby reducing the occurrence of lithium deposition and increasing the energy density of the negative electrode sheet.
Wherein at least one side of the current collector 10 is coated with the first coating 30, which may be understood as including: the surface of any side of the current collector 10 is coated with the first coating 30, and the surface of the first coating 30 is coated with the second coating 40 to form a single-side coating area of the current collector 10; the surfaces of the current collector 10 on opposite sides may be coated with the first coating layer 30, and the surface of each first coating layer 30 is coated with the second coating layer 40 to serve as a double-sided coating area of the current collector 10. How to coat the surface of the current collector 10 may be selected according to actual needs, and a single-side coating area and a double-side coating area may exist on the current collector 10.
In the embodiment of the present application, the second coating layer 40 includes a first region 41 and a second region 42, the first region 41 and the second region 42 are distributed along the first direction, the first region 41 is a region of the second coating layer 40 near the tab 20, the first coating layer 30 includes a first active material, the first active material includes graphite and a silicon-based material, the first region 41 of the second coating layer 40 includes a second active material, the second active material is graphite, the second region 42 of the second coating layer 40 includes a third active material, and the third active material includes graphite and a silicon-based material. The first coating 30 is less prone to lithium precipitation than the second coating 40, and the energy density can be improved by using a graphite doped silicon-based material as a first active material in the first coating 30; and the first region 41 of the second coating 40 is more prone to lithium precipitation than the second region 42, graphite with better conductivity is used as a second active material in the first region 41 of the second coating 40 close to the tab 20, and a graphite doped silicon-based material is used as a third active material in the second region 42 of the second coating 40 far away from the tab 20, so that the energy density is improved, the lithium precipitation is reduced, and the cycle performance of the negative plate is improved.
Alternatively, as shown in fig. 1 and 2, along the first direction, the first coating 30 includes a third region 31 and a fourth region 32, and the third region 31 is a region of the first coating 30 near the tab 20;
the third region 31 of the first coating 30 comprises a fourth active material, the fourth region 32 of the first coating 30 comprises a fifth active material, each of the fourth active material and the fifth active material comprises graphite and a silicon-based material, and the mass percentage of silicon in the fourth active material is less than or equal to the mass percentage of silicon in the fifth active material.
As shown in fig. 2, in the present embodiment, another negative electrode sheet is further provided, and the first coating 30 may be divided into the third region 31 and the fourth region 32 along the first direction (x-axis direction), and it can be understood that the third region 31 near the tab 20 in the first coating 30 is more susceptible to lithium deposition than the fourth region 32, so that the lithium deposition of the negative electrode sheet can be alleviated by making the mass percentage of silicon in the fourth active material of the third region 31 of the first coating 30 less than or equal to the mass percentage of silicon in the fifth active material of the fourth region 32 of the first coating 30.
Optionally, the percentage by mass of silicon in the fourth active material is a percentage in the percentage range of 0.1% to 20%, and the percentage by mass of silicon in the fifth active material is a percentage in the percentage range of 1% to 20%.
As shown in fig. 2, the first direction is a height direction (i.e., an x-axis direction) of the current collector 10 in the figure, and the silicon content in the third region 31 of the first coating 30 close to the tab 20 is less than or equal to the silicon content in the fourth region 32, so that the third region 31 is prevented from emitting lithium during high-rate charging, and the energy density can be increased by increasing the silicon content in the fourth region 32 while preventing lithium deposition.
Optionally, a third length of the third region 31 along the first direction is smaller than a fourth length of the fourth region 32 along the first direction.
By making the third length of the third region 31 in the first direction smaller than the fourth length of the fourth region 32 in the first direction, the silicon content of the entire negative electrode sheet is increased, and the energy density can be further increased.
In the embodiment of the present application, the first coating 30 includes a third region 31 and a fourth region 32, the third region 31 and the fourth region 32 are distributed along the first direction, and the third region 31 is a region of the first coating 30 near the tab 20; the third region 31 of the first coating 30 comprises a fourth active material, the fourth region 32 of the first coating 30 comprises a fifth active material, each of the fourth active material and the fifth active material comprises graphite and a silicon-based material, and the mass percentage of silicon in the fourth active material is less than or equal to the mass percentage of silicon in the fifth active material. Compared with the prior art that the silicon-based material doped in the graphite is coated on the surface of the current collector 10, the active material in the first coating 30 of the present application comprises the silicon-based material, and the silicon content in the fourth active material in the third region 31 of the first coating 30 is reduced, so that the energy density is increased, and the occurrence of lithium precipitation in the third region 31 of the first coating 30, which is relatively easy to precipitate lithium, can be avoided.
Optionally, a difference between the third length and the first length is less than or equal to 3 mm, and a difference between the fourth length and the second length is less than or equal to 3 mm;
the difference between the length of the first coating 30 in the first direction and the length of the second coating 40 in the first direction is less than or equal to 1 millimeter.
In this embodiment, the difference between the third length and the first length is less than or equal to 3 mm, and the difference between the fourth length and the second length is less than or equal to 3 mm, it can be understood that when the surface of the current collector 10 is coated with a coating, the third region 31 corresponds to the first region 41, and the fourth region 32 corresponds to the second region 42; the difference between the length of the first coating 30 in the first direction and the length of the second coating 40 in the first direction is less than or equal to 1 mm, the coating on the surface of the current collector 10 may be divided into the first region 41 where lithium is relatively difficult to be separated and the second region 42 where lithium is relatively easy to be separated, and silicon-based materials in active materials are respectively disposed according to the corresponding regions, so as to increase energy density and reduce lithium separation.
For ease of understanding, specific examples are as follows:
the embodiment of the application provides a negative plate, which has a structure as shown in fig. 3, and uses a copper foil as a current collector 10, and coats a layer C on the surface of the current collector 10, and coats a layer a and a layer B on the surface of the layer C. Wherein the active substance of the C layer is graphite blended silica material (silica material accounts for 1.8% of the total mass of the coating substance of the whole pole piece), the active substance of the A layer is graphite, and the active substance of the B layer is graphite blended silica material (silica material accounts for 0.2% of the total mass of the coating substance of the whole pole piece). The coating width of the layer A is 2.0 +/-1.0 mm, and the coating width of the layer B is 72.2 +/-1.0 mm. Through tests, the cycle performance of the battery comprising the negative plate is kept at 88.3% for 800 times, and the thickness of the battery expands 9.2%;
the application also provides a negative plate as a contrast, the structure of the negative plate is shown in fig. 4, the negative plate is in a normal coating mode, the copper foil is used as the current collector 10, and the coating is coated on the surface of the current collector 10. The active material of the coating is silicon-oxygen + graphite mixture, wherein the silicon-oxygen material accounts for 2.0% of the total mass of the coating substance of the whole pole piece. The coating width was 74.2 mm. Through tests, the battery containing the negative plate has the retention rate of 78.3% and the thickness expansion of 15.8% after 800 times of cycle performance.
The embodiment of the application also provides a negative plate, which has a structure as shown in fig. 3, and uses a copper foil as the current collector 10, and coats a layer C on the surface of the current collector 10, and coats a layer a and a layer B on the surface of the layer C. Wherein the C layer active substance is graphite blended silicon carbon material (the silicon carbon material accounts for 15.0% of the total mass of the whole pole piece coating substance), the A layer active substance is graphite, and the B layer active substance is graphite blended silicon carbon material (the silicon carbon material accounts for 5.0% of the total mass of the whole pole piece coating substance). The coating width of the layer A is 9.0 +/-1.0 mm, and the coating width of the layer B is 71.5 +/-1.0 mm. Through tests, the cycle performance of the battery comprising the negative plate is 80.8% after 400 times, and the thickness expansion is 11.7%;
the application also provides a negative plate as a contrast, the structure of the negative plate is shown in fig. 4, the negative plate is in a normal coating mode, the copper foil is used as the current collector 10, and the coating is coated on the surface of the current collector 10. The active material of the coating is silicon-oxygen + graphite mixture, wherein the silicon-oxygen material accounts for 20.0% of the total mass of the coating substance of the whole pole piece. The coating width was 80.5 mm. Through tests, the battery containing the negative plate has the retention rate of 66.1% and the thickness expansion of 24.9% after the cycle performance of 400 times.
The embodiment of the application also provides a negative plate, as shown in fig. 5, a copper foil is used as the current collector 10, a C + D layer is coated on one side of the current collector 10, and an a + B layer is coated on the C + D layer. The active substance of the layer C is a graphite mixed silica material (silica material accounts for 1.0% of the total mass of the whole pole piece coating substance), the active substance of the layer D is a graphite mixed silica material (silica material accounts for 1.2% of the total mass of the whole pole piece coating substance), the active substance of the layer A is graphite, and the active substance of the layer B is a graphite mixed silica material (silica material accounts for 0.8% of the total mass of the whole pole piece coating substance). The coating width of the layer A is 4.0 +/-1.0 mm, the coating width of the layer D is 4.0 +/-1.0 mm, the coating width of the layer B is 62.5 +/-1.0 mm, and the coating width of the layer C is 62.5 +/-1.0 mm. Through tests, the cycle performance of the battery comprising the negative plate is maintained at 88.9% for 600 times, and the thickness expansion is 10.1%;
the application also provides a negative plate as a contrast, the structure of the negative plate is shown in fig. 4, the negative plate is in a normal coating mode, the copper foil is used as the current collector 10, and the coating is coated on the surface of the current collector 10. The active material of the coating is silicon-oxygen + graphite mixture, wherein the silicon-oxygen material accounts for 2.0% of the total mass of the coating substance of the whole pole piece. The coating width was 66.5 mm. Through tests, the battery containing the negative plate has the retention rate of 80.8% and the thickness expansion of 20.8% after 600 times of cycle performance.
The embodiment of the application also provides a negative plate, as shown in fig. 5, the copper foil is used as the current collector 10, one surface of the current collector 10 is coated with a C + D layer, the C + D layer is coated with an a + B layer, the coating width a layer is 9.0 ± 1.0mm, the D layer is 9.0 ± 1.0mm, the B layer is 60.8 ± 1.0mm, and the C layer is 60.8 ± 1.0 mm. The active substance of the layer C is a graphite mixed silica material (silica material accounts for 15.0% of the total mass of the whole pole piece coating substance), the active substance of the layer D is a graphite mixed silica material (silica material accounts for 15.0% of the total mass of the whole pole piece coating substance), the active substance of the layer A is graphite, and the active substance of the layer B is a graphite mixed silica material (silica material accounts for 10% of the total mass of the whole pole piece coating substance). Through tests, the cycle performance of the battery comprising the negative plate is kept at 85.5% after 400 times, and the thickness expansion is 12.0%;
the application also provides a negative plate as a contrast, the structure of the negative plate is shown in fig. 4, the negative plate is in a normal coating mode, the copper foil is used as the current collector 10, and the coating is coated on the surface of the current collector 10. The active material of the coating is silicon-oxygen + graphite mixture, wherein the silicon-oxygen material accounts for 40.0% of the total mass of the coating substance of the whole pole piece. The coating width was 69.8 mm. Through tests, the battery containing the negative plate has the retention rate of 65.3% and the thickness expansion of 25.9% after the cycle performance of 400 times.
The negative plate provided by the embodiment of the application divides the coating on the current collector into a first coating (C + D layer) and a second coating (A + B layer), the second coating is coated on the surface of the first coating, the first coating is divided into a third area (D layer) and a fourth area (C layer) along the first direction, the second coating is divided into a first area (A layer) and a second area (B layer) along the first direction, the mass percentages of silicon in the active materials coated on the first area, the second area, the third area and the fourth area are respectively set, the first active material in the first area in the second coating uses graphite to avoid lithium precipitation caused by high-rate charging, the second active material in the second area uses silicon-based blending material in graphite to improve the energy density when viewed from the height direction of the negative plate, likewise, the silicon content in the third region in the first coating layer is greater than or equal to the silicon content in the fourth region; the first coating layer close to the current collector is more prone to lithium precipitation than the second coating layer when viewed from the thickness direction of the negative plate, and the silicon content in the fourth region can be larger than or equal to the silicon content in the second region to improve the energy density. Therefore, the problem of lithium separation of the negative plate during rapid charging is solved through the two dimensions of the height direction and the thickness direction of the negative plate, the cycle performance is improved, and the expansion of the negative plate caused by the volume expansion of the silicon-based material can be reduced.
The embodiment of the application further provides a battery, and the battery comprises the negative plate. It should be noted that the battery provided in the embodiment of the present application includes all the technical features in the foregoing embodiments of the negative electrode sheet, and can achieve the same technical effects, and for avoiding repetition, details are not described here again.
The embodiment of the application further provides an electronic device, and the electronic device comprises the battery. The electronic Device in the present application may be a mobile phone, a Tablet Personal Computer (Tablet Personal Computer), a notebook Computer, a palm top Computer (PDA), a vehicle-mounted electronic Device, a Wearable Device (Wearable Device), an Ultra-mobile Personal Computer (UMPC), a netbook, or the like.
While the foregoing is directed to the preferred embodiment of the present application, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the principles of the disclosure, and it is intended that such changes and modifications be considered as within the scope of the disclosure.
Claims (10)
1. The negative plate is characterized by comprising a current collector, a tab, a first coating and a second coating, wherein the tab is arranged at one end of the current collector and extends along a first direction of the current collector, the first coating is coated on the surface of at least one side of the current collector, and the second coating is coated on the surface of the first coating;
the first coating comprises a first active material, and the first active material comprises graphite and a silicon-based material; along the first direction, the second coating comprises a first area and a second area, the first area is an area, close to the tab, in the second coating, the first area of the second coating comprises a second active material, the second active material is graphite, the second area of the second coating comprises a third active material, and the third active material comprises graphite and a silicon-based material.
2. The negative electrode sheet of claim 1, wherein a first length of the first region in the first direction is less than a second length of the second region in the first direction, and the first length is a length in a length range of 1 to 10 mm and the second length is a length in a length range of 30 to 120 mm.
3. The negative electrode sheet of claim 1, wherein the mass percent of silicon in the first active material is greater than or equal to the mass percent of silicon in the third active material.
4. The negative electrode sheet of any one of claims 1 to 3, wherein the mass percentage of silicon in the first active material is a percentage in the percentage range of 0.1% to 20%, and the mass percentage of silicon in the third active material is a percentage in the percentage range of 0.1% to 10%.
5. The negative electrode sheet of claim 2, wherein along the first direction, the first coating layer includes a third region and a fourth region, and the third region is a region of the first coating layer adjacent to the tab;
the third region of the first coating comprises a fourth active material, the fourth region of the first coating comprises a fifth active material, the fourth active material and the fifth active material both comprise graphite and silicon-based materials, and the mass percent of silicon in the fourth active material is less than or equal to the mass percent of silicon in the fifth active material.
6. The negative electrode sheet of claim 5, wherein the mass percent of silicon in the fourth active material is a percent in the percentage range of 0.1% to 20%, and the mass percent of silicon in the fifth active material is a percent in the percentage range of 1% to 20%.
7. The negative electrode sheet of claim 5, wherein a third length of the third region in the first direction is less than a fourth length of the fourth region in the first direction.
8. The negative electrode sheet of claim 7, wherein the difference between the third length and the first length is less than or equal to 3 millimeters, and the difference between the fourth length and the second length is less than or equal to 3 millimeters; a difference between a length of the first coating layer in the first direction and a length of the second coating layer in the first direction is less than or equal to 1 millimeter.
9. A battery comprising the negative electrode sheet according to any one of claims 1 to 8.
10. An electronic device characterized in that the electronic device comprises the battery of claim 9.
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| CN115332478A (en) * | 2022-09-16 | 2022-11-11 | 江苏正力新能电池技术有限公司 | Pole piece, pole piece coating method and equipment |
| CN116705981A (en) * | 2023-07-27 | 2023-09-05 | 宁德时代新能源科技股份有限公司 | Negative electrode plate, preparation method thereof, battery and electric equipment |
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| CN113066954A (en) * | 2021-03-12 | 2021-07-02 | 珠海冠宇电池股份有限公司 | Negative plate and application thereof |
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| CN116705981A (en) * | 2023-07-27 | 2023-09-05 | 宁德时代新能源科技股份有限公司 | Negative electrode plate, preparation method thereof, battery and electric equipment |
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| CN114335424B (en) | 2024-06-14 |
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