High-energy-density sodium ion battery positive plate structure

Abstract

The utility model discloses a sodium ion battery positive plate structure with high energy density, which comprises a current collector, a composite positive electrode active material layer is arranged on the current collector, and the composite positive electrode active material layer comprises an active material inner layer, an active material middle layer and an active material outer layer which are sequentially coated on one surface or two surfaces of the current collector. The active material inner layer and the active material outer layer have the same material type, and the energy density of the active material middle layer is higher than that of the active material inner layer. The high-energy-density sodium ion battery positive plate structure has the characteristics of high energy density, good safety and simplicity in manufacturing.

Description

Technical Field

[0001] The utility model relates to the technical field of sodium ion batteries, in particular to a sodium ion battery positive electrode sheet structure with high energy density. Background Art

[0002] Among the positive electrode materials of sodium ion batteries, polyanionic compounds are an important type of positive electrode material. Polyanionic compounds are generally composed of cations and anionic groups. The anionic groups mainly include MOx polyhedron (x is V, Mn, Fe, Cr, Ti, etc.), (XO4)mn- or (XmO3m+1)n- (x is P, S, Si, As, etc.). n- or (XmO 3m+1 ) n- The three-dimensional structure is formed by sharing corners or edges. The anionic groups have strong covalent bonds and a stable structure, which has excellent thermal stability and cycling performance. However, its low specific capacity leads to a low overall energy density of the battery, which directly limits its expansion and application. Utility Model Content

[0003] The utility model aims to provide a high-energy-density sodium-ion battery positive electrode sheet structure, which has the characteristics of high energy density, good safety and simple production.

[0004] The utility model can be realized by the following technical solutions:

[0005] The utility model discloses a high-energy-density sodium-ion battery positive electrode sheet structure, comprising a current collector, on which a composite positive electrode active material layer is provided. The composite positive electrode active material layer comprises an active material inner layer, an active material middle layer, and an active material outer layer, which are sequentially coated on one or both sides of the current collector. The active material inner layer and the active material outer layer are of the same material type, and the energy density of the active material middle layer is higher than that of the active material inner layer.

[0006] Furthermore, the active material type of the active material intermediate layer is Na2MnO2, Na 2 / 3 (Ni 1 / 3 Mn 2 / 3 )O2、Na 2 / 3 (Mg 0.28 Mn 0.72 )O2、Na(Ni 1 / 2 Mn 1 / 2 )O2, Na 0.7 MnO2, Na(Ni 1 / 4 Fe 1 / 2 Mn 1 / 4 )One or more of O2.

[0007] Furthermore, the active materials of the inner active material layer and the outer active material layer are polyanion positive electrode materials.

[0008] Furthermore, the thickness of the inner layer of the active material is greater than the thickness of the outer layer of the active material, and the thickness of the outer layer of the active material is greater than the thickness of the middle layer of the active material.

[0009] Furthermore, the thickness ratio of the active material inner layer, the active material middle layer, and the active material outer layer is 5:2:3.

[0010] Furthermore, the current collector is aluminum foil, aluminum mesh, copper foil or copper mesh.

[0011] Furthermore, the sodium ion battery is a cylindrical steel shell battery, an aluminum shell battery or an aluminum-plastic film soft pack battery.

[0012] Furthermore, the bonding surfaces of the active material inner layer, the active material middle layer, and the active material outer layer are rough surfaces or irregularly textured surfaces.

[0013] Furthermore, the active material inner layer, the active material middle layer, and the active material outer layer are coated by extrusion coating, transfer coating, or roll coating.

[0014] Furthermore, a conductive adhesive layer is provided between the contact surfaces of the current collector, the inner active material layer, the middle active material layer, and the outer active material layer.

[0015] The utility model provides a high energy density sodium ion battery positive electrode sheet structure, which has the following beneficial effects:

[0016] First, high energy density. The applied active material intermediate layer acts as an energy-enhancing layer, significantly increasing the battery's energy density. Taking a 1Ah battery as an example (Example 1), the battery with the energy-enhancing layer has a higher energy density than a conventional polyanion battery.

[0017] Second, high stability. Polyanion batteries are widely used due to their advantages of thermal stability and high safety. Batteries with an energy-enhancing layer can continue to maintain these advantages. Taking a 1Ah battery as an example (Example 1), the battery with an energy-enhancing layer passed the safety (needle puncture) test and found that the temperature rise after needle puncture was as high as 60°C, and it did not catch fire or explode, and would not cause any harm to the user.

[0018] Third, the production is simple. In the positive electrode sheet structure of the present invention, the inner layer of active material and the outer layer of active material are both made of the same active material, and the same slurry can be used to coat the middle layer of active material with high energy density in the middle, effectively simplifying the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Attachment Figure 1This is a schematic diagram of the exploded structure of a high energy density sodium ion battery positive electrode structure of the utility model;

[0020] Figure 2 This is a comparison of the energy density of the sodium ion battery of Example 1 and the prior art polyanion sodium ion battery;

[0021] Figure 3 This is a comparison of the acupuncture test of the sodium ion battery of Example 1 and the prior art polyanion sodium ion battery;

[0022] Reference numerals in the drawings include: 100, current collector; 201, inner active material layer; 202, middle active material layer; 203, outer active material layer. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in further detail below in conjunction with embodiments.

[0024] like Figure 1 As shown, the utility model discloses a high energy density sodium ion battery positive electrode sheet structure, including a current collector 100, on which a composite positive electrode active material layer is provided. The composite positive electrode active material layer includes an active material inner layer 201, an active material middle layer 202, and an active material outer layer 203 sequentially coated on one or both sides of the current collector 100. The active material inner layer 201 and the active material outer layer 203 are of the same material type, and the energy density of the active material middle layer 202 is higher than that of the active material inner layer 201.

[0025] Furthermore, the active material type of the active material intermediate layer is Na2MnO2, Na 2 / 3 (Ni 1 / 3 Mn 2 / 3 )O2、Na 2 / 3 (Mg 0.28 Mn 0.72 )O2、Na(Ni 1 / 2 Mn 1 / 2 )O2, Na 0.7 MnO2, Na(Ni 1 / 4 Fe 1 / 2 Mn 1 / 4 )One or more of O2.

[0026] Furthermore, the active materials of the inner active material layer and the outer active material layer are polyanion positive electrode materials.

[0027] Furthermore, the thickness of the inner layer of the active material is greater than the thickness of the outer layer of the active material, and the thickness of the outer layer of the active material is greater than the thickness of the middle layer of the active material.

[0028] Furthermore, the thickness ratio of the active material inner layer, the active material middle layer, and the active material outer layer is 5:2:3.

[0029] Furthermore, the current collector is aluminum foil, aluminum mesh, copper foil or copper mesh.

[0030] Furthermore, the sodium ion battery is a cylindrical steel shell battery, an aluminum shell battery or an aluminum-plastic film soft pack battery.

[0031] Furthermore, the bonding surfaces of the active material inner layer, the active material middle layer, and the active material outer layer are rough surfaces or irregularly textured surfaces.

[0032] Furthermore, the active material inner layer, the active material middle layer, and the active material outer layer are coated by extrusion coating, transfer coating, or roll coating.

[0033] Furthermore, a conductive adhesive layer is provided between the contact surfaces of the current collector, the inner active material layer, the middle active material layer, and the outer active material layer. Example

[0034] The preparation method of the composite positive electrode sheet of the sodium ion battery of this embodiment is as follows:

[0035] Polyanion layer (active material inner layer, active material outer layer): binder PVDF; conductive agents SP, CNTS; polyanion active material Na4Fe3(PO4)2 (P2O7) slurry according to the mass ratio of 2.5%:1%:1%:95.5%;

[0036] Energy-enhancing layer (active material intermediate layer): binder PVDF; conductive agent SP, CNTS; active material Na(Ni 1 / 4Fe 1 / 2 Mn 1 / 4 ) O2 is slurried according to 3%:1%:1%:95%;

[0037] The polyanion slurry (active material inner layer) is applied to the aluminum foil (12μm) in sequence, and the thickness after application and drying is 125μm. The energy-enhancing layer (active material middle layer) is applied to the dried polyanion slurry (active material inner layer), and the thickness after application and drying is 175μm. The polyanion slurry (active material outer layer) is then applied to the dried energy-enhancing layer (active material middle layer), and the thickness after application and drying is 251μm.

[0038] By assembling the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. into a sodium ion battery, a polyanion type sodium ion battery with high energy density can be obtained.

[0039] In order to facilitate the evaluation of the technical effect of the present invention, the energy density and needle puncture test results of the sodium ion battery prepared in this embodiment are compared with those of the sodium ion battery in the prior art in which all three layers are polyanion active material Na4Fe3(PO4)2 (P2O7). The results are as follows: Figure 2 and Figure 3 shown. Example

[0040] The preparation method of the composite positive electrode sheet of the sodium ion battery of this embodiment is as follows:

[0041] Polyanion layer (active material inner layer, active material outer layer): binder PAA; conductive agents SP, CNTS; polyanion active material Na4Fe3(PO4)2 (P2O7) slurry according to the mass ratio of 2%:1%:1%:96%;

[0042] Energy-enhancing layer (active material intermediate layer): binder PAA; conductive agent SP, CNTS; active material Na(Ni 1 / 4Fe 1 / 2 Mn 1 / 4 ) O2 is slurried according to 2.5%:1%:1%:95.5%;

[0043] The polyanion slurry (active material inner layer) is applied to the aluminum foil (12μm) in sequence, and the thickness after application and drying is 120μm. The energy-enhancing layer (active material middle layer) is applied to the dried polyanion slurry (active material inner layer), and the thickness after application and drying is 170μm. The polyanion slurry (active material outer layer) is then applied to the dried energy-enhancing layer (active material middle layer), and the thickness after application and drying is 251μm.

[0044] By assembling the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. into a sodium ion battery, a polyanion type sodium ion battery with high energy density can be obtained. Example

[0045] The preparation method of the composite positive electrode sheet of the sodium ion battery of this embodiment is as follows:

[0046] Polyanion layer (active material inner layer, active material outer layer): binder PVDF; conductive agents SP, KS-6; polyanion active material Na2Fe2(SO4)3 slurry according to the mass ratio of 4%:1.5%:0.5%:94%;

[0047] Energy-enhancing layer (active material intermediate layer): binder PVDF; conductive agent SP, conductive graphite; active material Na 2 / 3 (Ni 1 / 3 Mn 2 / 3)O2, pulping according to 3%:1%:1%:95%;

[0048] The polyanion slurry (active material inner layer) is applied to the aluminum foil (12μm) in sequence, and the thickness after application and drying is 125μm. The energy-enhancing layer (active material middle layer) is applied to the dried polyanion slurry (active material inner layer), and the thickness after application and drying is 175μm. The polyanion slurry (active material outer layer) is then applied to the dried energy-enhancing layer (active material middle layer), and the thickness after application and drying is 251μm.

[0049] By assembling the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. into a sodium ion battery, a polyanion type sodium ion battery with high energy density can be obtained. Example

[0050] The preparation method of the composite positive electrode sheet of the sodium ion battery of this embodiment is as follows:

[0051] Polyanion layer (active material inner layer, active material outer layer): binders PVDF, PAA; conductive agents SP, CNTS; polyanion active material Na4Fe3(PO4)2 (P2O7) slurry according to the mass ratio of 2%:2%:1%:1%:94%;

[0052] Energy-enhancing layer (active material intermediate layer): binder PVDF; conductive agent SP, conductive graphite; active material Na 2 / 3 (Ni 1 / 3 Mn 2 / 3 )O2, pulping according to 3%:1%:1%:95%;

[0053] The polyanion slurry (active material inner layer) is applied to the aluminum foil (12μm) in sequence, and the thickness after application and drying is 125μm. The energy-enhancing layer (active material middle layer) is applied to the dried polyanion slurry (active material inner layer), and the thickness after application and drying is 175μm. The polyanion slurry (active material outer layer) is then applied to the dried energy-enhancing layer (active material middle layer), and the thickness after application and drying is 251μm.

[0054] By assembling the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. into a sodium ion battery, a polyanion type sodium ion battery with high energy density can be obtained. Example

[0055] The preparation method of the composite positive electrode sheet of the sodium ion battery of this embodiment is as follows:

[0056] Polyanion layer (active material inner layer, active material outer layer): binder PVDF; conductive agents SP, CNTS; polyanion active material Na3V2(PO4)3 slurry according to the mass ratio of 3%:1%:1%:95%;

[0057] Energy-enhancing layer (active material intermediate layer): binder PVDF; conductive agent SP, CNTS; active material Na(Ni 1 / 4Fe 1 / 2 Mn 1 / 4 )O2, pulping according to 3%:1.5%:1%:94.5%;

[0058] The polyanion slurry (active material inner layer) is applied to the aluminum foil (12μm) in sequence, and the thickness after application and drying is 125μm. The energy-enhancing layer (active material middle layer) is applied to the dried polyanion slurry (active material inner layer), and the thickness after application and drying is 175μm. The polyanion slurry (active material outer layer) is then applied to the dried energy-enhancing layer (active material middle layer), and the thickness after application and drying is 251μm.

[0059] By assembling the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. into a sodium ion battery, a polyanion type sodium ion battery with high energy density can be obtained. Example

[0060] The preparation method of the composite positive electrode sheet of the sodium ion battery of this embodiment is as follows:

[0061] Polyanion layer (active material inner layer, active material outer layer): binder PVDF; conductive agents SP, CNTS; polyanion active material Na4Fe3(PO4)2 (P2O7) slurry according to the mass ratio of 3%:1%:1%:95%;

[0062] Energy-enhancing layer (active material intermediate layer): binder PVDF; conductive agents SP, CNTS; active material Na(Ni1 / 4Fe1 / 2Mn1 / 4)O2 slurry is prepared according to the ratio of 3%:1%:1%:95%;

[0063] The polyanion slurry (active material inner layer) is applied to the aluminum foil (12μm) in sequence, and the thickness after application and drying is 150μm. The energy-enhancing layer (active material middle layer) is applied to the dried polyanion slurry (active material inner layer), and the thickness after application and drying is 210μm. The polyanion slurry (active material outer layer) is then applied to the dried energy-enhancing layer (active material middle layer), and the thickness after application and drying is 311μm.

[0064] By assembling the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. into a sodium ion battery, a polyanion type sodium ion battery with high energy density can be obtained.

[0065] In the description of the present invention, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0066] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0067] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0068] The above embodiments are merely specific embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art will be able to make various modifications and improvements without departing from the scope of the present invention, and these obvious alternatives are all within the scope of protection of the present invention.

Claims

1. A high energy density sodium ion battery cathode structure, comprising a current collector, characterized in that: A composite positive electrode active material layer is provided on the current collector, and the composite positive electrode active material layer includes an active material inner layer, an active material middle layer, and an active material outer layer sequentially coated on one or both sides of the current collector. The active material inner layer and the active material outer layer are of the same material type, and the energy density of the active material middle layer is higher than that of the active material inner layer.

2. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The active materials of the active material inner layer and the active material outer layer are polyanion positive electrode materials.

3. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The thickness of the inner active material layer is greater than the thickness of the outer active material layer, and the thickness of the outer active material layer is greater than the thickness of the middle active material layer.

4. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The thickness ratio of the active material inner layer, the active material middle layer, and the active material outer layer is 5:2:

3.

5. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The current collector is aluminum foil, aluminum mesh, copper foil or copper mesh.

6. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The sodium ion battery is a cylindrical steel shell battery, an aluminum shell battery or an aluminum-plastic film soft package battery.

7. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The bonding surfaces of the active material inner layer, the active material middle layer, and the active material outer layer are rough surfaces or irregularly textured surfaces.

8. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: The active material inner layer, the active material middle layer and the active material outer layer are coated by extrusion coating, transfer coating or roller coating.

9. The high energy density sodium ion battery positive electrode sheet structure according to claim 1, characterized in that: A conductive adhesive layer is further provided between the contact surfaces of the current collector, the active material inner layer, the active material middle layer, and the active material outer layer.

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