High-safety positive pole piece and battery

Abstract

The utility model relates to a high-safety positive pole piece and a battery, the high-safety positive pole piece comprises a positive pole current collector and a positive pole active material layer arranged on the positive pole current collector, and further comprises a non-active material layer arranged on the positive pole current collector and surrounding the positive pole active material layer, the inner peripheral surface of the non-active material layer is in contact with the outer peripheral surface of the positive electrode active material layer. According to the all-solid-state battery, the non-active material layer surrounding the positive active material layer is arranged on the positive current collector, so that the sizes of the positive pole piece, the electrolyte membrane and the negative pole piece are consistent, and the all-solid-state battery is assembled, so that on one hand, the problem that the electrolyte membrane is broken due to inconsistent sizes of the positive pole piece and the negative pole piece can be effectively solved; on the other hand, due to the structural arrangement of the non-active material layer in the positive pole piece, lithium precipitation on the surface of the negative pole can be prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a highly safe positive electrode plate and a battery. Background Art

[0002] A all-solid-state battery is a battery that uses a solid electrolyte, and its overall performance is more stable. In extreme environments such as collision and extrusion, the battery is not prone to explosion and combustion, which means higher battery safety. However, since the components in the all-solid-state battery are in solid-solid contact, in order to achieve better contact between particles, a large pressure is required during battery assembly and testing. Generally speaking, the assembly pressure of the solid-state battery is greater than 300 MPa, and the testing pressure is greater than 20 MPa.

[0003] To prevent lithium plating in the battery, the area of the positive electrode plate is usually slightly smaller than that of the negative electrode plate. In a liquid battery, there is no problem with this structure of the electrode plate. However, for an all-solid-state battery, when applying a large pressure to assemble and test the battery, since the positive electrode plate is relatively small, cracks are likely to occur at the place where the electrolyte membrane contacts the positive electrode plate, and even the entire edge electrolyte layer may fall off, resulting in a short circuit of the solid-state battery. When assembling a battery with a positive electrode plate, a negative electrode plate, and an electrolyte membrane of the same size and similar thickness, the situation of electrolyte membrane rupture during high-pressure assembly and testing can be effectively solved. However, when the size of the positive electrode plate is the same as that of the negative electrode plate, due to reasons such as the assembly process and coating accuracy, lithium dendrites are likely to grow on the surface of the negative electrode plate, causing a short circuit of the battery and reducing the battery life. Summary of the Utility Model

[0004] Based on this, in view of the technical problems existing in the current all-solid-state battery, the utility model proposes a highly safe positive electrode plate and a battery.

[0005] A highly safe positive electrode plate provided by the utility model includes a positive current collector and a positive active material layer provided on the positive current collector. It further includes a non-active material layer provided on the positive current collector and surrounding the positive active material layer, and the inner peripheral surface of the non-active material layer is in contact with the outer peripheral surface of the positive active material layer.

[0006] By providing a non-active material layer surrounding the positive active material layer on the positive current collector, the utility model makes the positive electrode plate, the electrolyte membrane, and the negative electrode plate have the same size and assemble them into an all-solid-state battery. On the one hand, it can effectively solve the problem of electrolyte membrane rupture caused by the inconsistent sizes of the positive electrode plate and the negative electrode plate. On the other hand, due to the structural setting of the non-active material layer in the positive electrode plate, it can prevent lithium plating on the surface of the negative electrode. The non-active material layer of the utility model can be obtained by exposing the active material to humid air to make the active material ineffective and then drying it by vacuum pumping.

[0007] As a further improvement of the above solution of the present utility model, the thickness of the non-active material layer is the same as that of the positive active material layer.

[0008] As a further improvement of the above solution of the present utility model, the positive active material layer is in a rectangular structure, and the non-active material layer is in a square frame structure.

[0009] As a further improvement of the above solution of the present utility model, the positive current collector is carbon-coated aluminum foil or aluminum foil.

[0010] A battery provided by the present utility model includes a positive electrode plate, an electrolyte membrane, and a negative electrode plate with the same size, and the positive electrode plate adopts the high-safety positive electrode plate as described above.

[0011] Compared with the prior art, the present utility model has the following beneficial effects:

[0012] 1. For the high-safety positive electrode plate provided by the present utility model, by arranging a non-active material layer around the positive active material layer on the positive current collector, the positive electrode plate has the same size as the electrolyte membrane and the negative electrode plate, and is assembled into an all-solid-state battery. On the one hand, during isostatic pressing assembly and pressure testing, the entire battery is evenly stressed, greatly reducing the probability of microcracks appearing on the electrolyte membrane due to inconsistent positive and negative electrode sizes, improving the battery assembly success rate. On the other hand, due to the structural arrangement of the non-active material layer in the positive electrode plate, it can ensure that the battery has an overhang, prevent lithium deposition on the negative electrode surface, improve the safety performance and cycle life of the battery. At the same time, due to the same size, each component is easier to align, making the assembly of the all-solid-state battery easier to achieve.

[0013] 2. The high-safety positive electrode plate provided by the present utility model provides a new idea for the mass production of all-solid-state soft-pack batteries. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of a high-safety positive electrode plate proposed by an embodiment of the present utility model;

[0015] Figure 2 It is the first discharge curve of the all-solid-state battery in an embodiment of the present utility model.

[0016] Reference numerals: 1. Positive active material layer; 2. Non-active material layer. Detailed Embodiments

[0017] To facilitate the understanding of the present utility model, the present utility model will be described more comprehensively below in conjunction with specific embodiments. However, the present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present utility model more thorough and comprehensive.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this utility model belongs. The terms used in the description of this utility model herein are only for the purpose of describing specific embodiments and are not intended to limit this utility model.

[0019] Referring to Figure 1 , this embodiment provides a highly secure positive electrode plate, which includes a positive current collector and a positive active material layer 1 and an inactive material layer 2 provided on the positive current collector. Among them: the positive current collector is carbon-coated aluminum foil or porous aluminum foil. The positive active material layer 1 has a rectangular structure, and the inactive material layer 2 has a square frame structure. The inactive material layer 2 is arranged around the positive active material layer 1 and the inner peripheral surface of the inactive material layer 2 is in contact with the outer peripheral surface of the positive active material layer 1, and the thickness of the inactive material layer 2 is the same as the thickness of the positive active material layer 1. In this embodiment, the inactive material layer 2 can be obtained by exposing the active material to wet air to make the active material ineffective and then drying it by vacuum pumping.

[0020] In this embodiment, by providing an inactive material layer 2 arranged around the positive active material layer 1 on the positive current collector, the positive electrode plate can be made to have the same size as the electrolyte membrane and the negative electrode plate, and assembled into an all-solid-state battery. On the one hand, it can effectively solve the problem of electrolyte membrane rupture caused by the inconsistent size of the positive electrode plate and the negative electrode plate. On the other hand, due to the structural setting of the inactive material layer in the positive electrode plate, the negative overhang can still be maintained, which can prevent lithium deposition on the surface of the negative electrode and improve the cycle life of the battery.

[0021] The highly secure positive electrode plate of this embodiment can be prepared according to the following steps:

[0022] S1. Prepare a positive electrode paste and a positive electrode sheet.

[0023] In this embodiment, the positive electrode sheet is prepared by the wet coating method. The specific process is as follows: Weigh the active positive electrode material NCM83, the sulfide electrolyte Li 6 PS 5 Cl, the conductive agent VGCF and the binder SEBS according to the mass ratio of 85:15:1.5:1.5; dissolve the binder in anisole solvent to obtain a binder solution, mix the binder solution with the active positive electrode, the conductive agent and the sulfide electrolyte and ball-mill to obtain a positive active material paste, coat the positive active material paste on a release aluminum foil with weak bonding force (release force less than 30 g), and dry it by vacuum pumping at 70 °C to obtain a wet positive electrode sheet.

[0024] Of course, in other embodiments, the positive electrode sheet can also be prepared by dry rolling. The specific process can be as follows: Weigh the active positive electrode material NCM83, sulfide electrolyte Li 6 PS 5 Cl, conductive agent VGCF and binder ptfe according to the mass ratio of 85:15:1.5:1.5. Heat all the materials to 60 °C, premix them in a mortar to make the components evenly distributed, and then repeatedly roll them in an inert atmosphere to a predetermined thickness to obtain a dry-process positive electrode sheet.

[0025] It should be noted that in other embodiments, the active positive electrode material can also be lithium sulfide, lithium cobaltate with a coating layer, lithium nickelate with a coating layer, lithium-rich manganese-based with a coating layer, lithium iron phosphate manganese with a coating layer, lithium nickel cobalt aluminate with a coating layer, lithium nickel cobalt manganate with a coating layer or lithium iron phosphate with a coating layer; the sulfide electrolyte can also be LGPS, Li 3 PS 4 、Li 7 P 3 S 11 、Li 7 P 2 S 8 I or LiSiPSX, where X is selected from at least one of F, Cl, Br, and I.

[0026] S2. Die-cut the positive electrode sheet according to the shapes of the positive electrode active material layer 1 and the non-active material layer 2 to obtain a first active material area with a rectangular structure and a second active material area with a square structure, respectively.

[0027] The thickness and components of the first active material area and the second active material area are the same, and the sizes of the first active material area and the second active material area can be reasonably designed according to actual needs. In this embodiment, the size of the first active material area with a rectangular structure is 9.3 cm × 12.3 cm, and the width of the second active material area with a square structure is greater than 1 cm. Of course, in other embodiments, the first active material area and the second active material area can also be of other sizes.

[0028] S3. Expose the second active material area to humid air to render the active positive electrode material and the sulfide electrolyte ineffective, and then dry it by vacuum at 70 °C to obtain a non-active material area.

[0029] It should be noted that the exposure time of the second active material area in humid air depends on the actual situation and is not less than 20 days, based on the inactivation of the active positive electrode material and the sulfide electrolyte and the formation of non-active salt rock phase nickel oxide on the surface of the positive electrode material. In this embodiment, the second active material area is exposed to humid air with a humidity of 80% and a temperature of 60 °C for 30 days. Of course, in other embodiments, the second active material area can also be exposed to humid air with a humidity of 70% and a temperature of 80 °C for 25 days.

[0030] S4. After arranging the inactive material region around the first active material region, it is transferred to the positive current collector with strong binding force by isostatic pressing or rolling, and then die-cut to obtain a highly safe positive electrode sheet. In this embodiment, the size of the highly safe positive electrode sheet is 9.6 cm × 12.6 cm, and the width of the inactive material layer is 0.3 cm.

[0031] This embodiment also provides a all-solid-state battery, which includes a positive electrode sheet, an electrolyte membrane, and a negative electrode sheet. The sizes of the positive electrode sheet, the electrolyte membrane, and the negative electrode sheet are all 9.6 cm × 12.6 cm.

[0032] When preparing the all-solid-state battery of this embodiment, first prepare the electrolyte membrane|negative electrode composite sheet: ① Preparation of the electrolyte membrane: Weigh the sulfide electrolyte Li 6 PS 5 Cl and the binder SEBS according to the ratio of 96:4. Dissolve the binder in anisole to obtain a binder solution; mix the sulfide electrolyte and the binder solution and ball-mill to obtain an electrolyte slurry. Coat the electrolyte slurry on a pet release film and dry it under vacuum at 70 °C; ② Preparation of the negative electrode sheet: Weigh the silicon-carbon material, sulfide electrolyte, and binder according to the ratio of 70:28.5:1.5; dissolve the binder SEBS in anisole to obtain a binder solution; mix the silicon-carbon, sulfide electrolyte and the binder solution, ball-mill at 300 rpm for 50 min to obtain a negative electrode slurry, coat the slurry on a copper foil, and dry it under vacuum at 80 °C to obtain a negative electrode sheet; ③ Transfer the electrolyte membrane to the surface of the negative electrode sheet by rolling to obtain the electrolyte membrane|negative electrode composite sheet. Then stack the positive electrode sheet, electrolyte membrane, and negative electrode sheet in sequence according to the required capacity, weld the electrode tabs, encapsulate under vacuum, and perform isostatic pressing at 500 MPa for 6 min to obtain the sulfide all-solid-state battery.

[0033] The all-solid-state battery of this embodiment is tested under the conditions of 60 MPa and 55 °C, and the test results are shown in Table 1, Figure 2 as shown.

[0034] Table 1

[0035] Load First effect First discharge (0.1C) 0.2C Retention rate of 0.2C cycle (%) <![CDATA[4mAh / cm 2 > 80％ 192 mAh / g 185 mAh / g 95.1 (50 cycles)

[0036] From Table 1, Figure 2 the results show that the all-solid-state soft-pack battery prepared with this highly safe positive electrode sheet does not show a short-circuit phenomenon under a high pressure of 500 MPa and can stably cycle in a 60 MPa pressure device. The structure of this positive electrode sheet improves the success rate of battery assembly and testing. If the negative electrode is large and the positive electrode is small like a traditional liquid battery to assemble a solid-state battery, the electrolyte membrane will crack due to uneven stress during isostatic pressing, resulting in battery short-circuit.

[0037] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0038] The above-described embodiments only represent several implementation manners of the present utility model, and the description is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the utility model patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several deformations and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the utility model patent shall be subject to the appended claims.

Claims

1. A high-safety positive electrode plate, comprising a positive electrode current collector and a positive electrode active material layer (1) arranged on the positive electrode current collector, characterized in that: It also includes an inactive material layer (2) arranged on the positive electrode current collector and surrounding the positive electrode active material layer (1), and the inner peripheral surface of the inactive material layer (2) is in contact with the outer peripheral surface of the positive electrode active material layer (1).

2. The high-safety positive electrode sheet according to claim 1, characterized in that: The thickness of the inactive material layer (2) is consistent with the thickness of the positive electrode active material layer (1).

3. The high-safety positive electrode sheet according to claim 1, characterized in that: The positive electrode active material layer (1) has a rectangular structure.

4. The high-safety positive electrode sheet according to claim 3, characterized in that: The inactive material layer (2) is in a square frame structure.

5. The high-safety positive electrode sheet according to claim 1, characterized in that: The positive electrode current collector is a carbon-coated aluminum foil or a porous aluminum foil.

6. A battery comprising a positive electrode sheet, an electrolyte membrane, and a negative electrode sheet of uniform size, characterized in that: The positive electrode plate adopts the high-safety positive electrode plate as described in any one of claims 1-5.

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