Flexible bipolar solid sodium battery

Abstract

The utility model belongs to the technical field of batteries, and discloses a flexible bipolar solid sodium battery which comprises a sodium metal negative electrode layer, an NZSP-based composite electrolyte layer, a plurality of flexible bipolar composite electrodes, an NZSP-based composite electrolyte layer, a sodium vanadium phosphate positive electrode layer and an aluminum coating polyethylene glycol terephthalate fabric core layer which are sequentially arranged from top to bottom, an NZSP-based composite electrolyte layer is arranged between the flexible bipolar composite electrode and the flexible bipolar composite electrode, and the flexible bipolar composite electrode comprises a sodium vanadium phosphate positive electrode layer, an aluminum coating polyethylene glycol terephthalate fabric core layer and a sodium metal negative electrode layer which are sequentially arranged from top to bottom. The solid-state sodium battery has the beneficial effects that direct series connection in single bodies can be realized, the output voltage is improved, inert connecting materials are reduced, the energy density of the solid-state sodium battery is improved, and the solid-state sodium battery has flexibility, can be bent and deformed and is suitable for wearable electronic equipment.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a flexible bipolar solid-state sodium battery. Background Art

[0002] Sodium-ion batteries are regarded as a preferred technology for large-scale energy storage applications due to their rich resources and low cost. Globally, many enterprises have incorporated sodium-ion batteries into their development blueprints. With the release of sodium-ion battery products by enterprises such as CATL, their commercialization process is approaching. However, sodium-ion batteries still face challenges in terms of safety, as the organic electrolytes they use are flammable and prone to leakage. To address this issue, solid-state sodium batteries exhibit higher safety due to the use of sodium-ion solid electrolytes that are not flammable, do not produce gas, and do not explode.

[0003] With the rapid development of flexible electronic devices such as biosensors, rollable displays, and wearable electronic products, the demand for flexible battery technology is increasing day by day. These devices usually require batteries to have a high working voltage and energy density. Traditional liquid sodium-ion batteries are limited by the fluidity of the electrolyte and usually need to connect multiple battery units in series to increase the output voltage, which not only increases the mass of inactive materials but also reduces the energy density of the battery.

[0004] In the research of solid-state battery technology, improving the solid-solid contact between the electrolyte and the electrode and realizing the internal series connection of solid-state batteries are the current research focuses. In the prior art, solid-state batteries achieve the fitting of the electrode and the electrolyte through physical compression, but this method is difficult to achieve the good contact effect brought by the fluidity of the electrolyte in liquid batteries, resulting in a large interfacial impedance and affecting the battery performance and life. In addition, the internal series connection technology of solid-state batteries is expected to achieve ultra-high energy density due to its physical stability and is the key to the development of battery technology.

[0005] Chinese Patent Application CN116706217A discloses a bipolar all-solid-state sodium-ion secondary battery, which adopts a scheme of physically fitting the positive electrode, electrolyte, and negative electrode after independent preparation and directly uses a ceramic solid electrolyte. However, this design may lead to a large interfacial impedance at the positive / negative electrode interface, affecting the cycle stability of the battery, and the high density of the ceramic electrolyte may reduce the energy density of the battery. Another Chinese Patent Application CN117712511A discloses a battery based on NZSP (Na1+xZr2Si x P3- xO 12A bipolar solid-state sodium battery with a composite electrolyte membrane (0 ≤ x ≤ 3) uses hard carbon or bamboo carbon as the anode material instead of sodium metal with better adhesion, which may lead to a large interfacial impedance at the anode / electrolyte interface and lack sufficient flexibility, making it difficult to meet the application requirements of wearable devices. English literature (Advanced Materials, 2024, 2406386) reported a flexible bipolar solid-state lithium metal battery using a bipolar textile composite electrode (nickel-coated polyethylene terephthalate fabric (NiPET) as the core layer, coated with a LiFePO4 cathode and a lithium metal anode on both sides). However, for solid-state sodium batteries, no similar reports have been seen, and sodium may alloy with nickel, which brings new challenges to the design and application of solid-state sodium batteries.

[0006] Therefore, it is necessary to provide a flexible bipolar solid-state sodium battery that can directly series-connect within a single body to increase the output voltage, reduce inert connection materials, and improve the energy density of the solid-state sodium battery. Summary of the Invention

[0007] The utility model discloses a flexible bipolar solid-state sodium battery, which can effectively solve the technical problems involved in the background art.

[0008] To achieve the above object, the technical solution of the utility model is as follows:

[0009] A flexible bipolar solid-state sodium battery includes a sodium metal anode layer, an NZSP-based composite electrolyte layer, a plurality of flexible bipolar composite electrodes, an NZSP-based composite electrolyte layer, a sodium vanadium phosphate cathode layer, and an aluminum-coated polyethylene terephthalate fabric core layer arranged in sequence from top to bottom. An NZSP-based composite electrolyte layer is provided between the flexible bipolar composite electrodes. The flexible bipolar composite electrode includes a sodium vanadium phosphate cathode layer, an aluminum-coated polyethylene terephthalate fabric core layer, and a sodium metal anode layer arranged in sequence from top to bottom.

[0010] As a preferred improvement of the utility model: The number of the flexible bipolar composite electrodes is 2 - 6.

[0011] As a preferred improvement of the utility model: The thickness of the sodium metal anode layer is 20 - 50 um.

[0012] As a preferred improvement of the utility model: The thickness of the NZSP-based composite electrolyte layer is 50 - 100 um.

[0013] As a preferred improvement of the utility model: The thickness of the sodium vanadium phosphate cathode layer is 100 - 200 um.

[0014] As a preferred improvement of the present utility model: the thickness of the aluminum-coated polyethylene terephthalate fabric core layer is 20-50um.

[0015] As a preferred improvement of the present utility model: the battery is encapsulated with an aluminum-plastic film.

[0016] The beneficial effects of the present utility model are as follows:

[0017] A solid-state sodium battery is disclosed. The solid-state sodium battery has a flexible bipolar composite electrode. By stacking with a composite solid electrolyte, it can achieve direct series connection within a single body to increase the output voltage, reduce inert connection materials, improve the energy density of the solid-state sodium battery, and at the same time has flexibility and can be bent and deformed, making it suitable for wearable electronic devices. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, where:

[0019] Figure 1 It is a schematic diagram of a flexible bipolar solid-state sodium battery of the present utility model.

[0020] In the figure: 1 - sodium metal negative electrode layer, 2 - NZSP-based composite electrolyte layer, 3 - sodium vanadium phosphate positive electrode layer, 4 - aluminum-coated polyethylene terephthalate fabric core layer, 5 - flexible bipolar composite electrode. Specific Embodiments

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0023] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0024] In the present invention, unless otherwise clearly defined and limited, the terms "connected", "fixed", etc. shall be understood in a broad sense. For example, "fixed" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0026] Patent CN116706217A, bipolar all-solid-state sodium secondary battery; Patent CN117712511A, a bipolar solid-state sodium battery with an NZSP-based composite electrolyte membrane, its preparation method and application; Paper Zhenyao Wei, YufengLuo, Wancheng Yu et al. Bipolar Textile Composite Electrodes EnablingFlexible Tandem Solid-State Lithium Metal Batteries. Advanced Materials, 2024, 2406386; The above-mentioned documents disclose several batteries. However, the electrode / electrolyte interface impedance of the bipolar solid-state sodium battery is large, which cannot be charged and discharged quickly, and at the same time leads to a decrease in the energy density of the battery. The bipolar solid-state sodium battery uses hard carbon or bamboo carbon as the negative electrode material, which does not have good flexibility and is difficult to be applied to wearable electronic devices. The nickel in the nickel-coated polyethylene terephthalate fabric (NiPET) core layer is stable to lithium metal, but will alloy with sodium, resulting in a decrease in cycle stability. To solve the above problems, the present utility model adopts a flexible bipolar composite electrode, which uses an aluminum-coated polyethylene terephthalate fabric core layer (AlPET), and the sodium vanadium phosphate (Na3V2(PO4)3) positive electrode and the sodium metal negative electrode are respectively coated on both sides. Alternately stacking the flexible bipolar composite electrode with the NZSP (Na3Zr2Si2PO 12 )-based composite solid electrolyte can increase the output voltage (10-20V), reduce the inert packaging filler, and increase the energy density of the battery monomer, and is applied to flexible wearable electronic devices. Its structure is a sodium metal negative electrode, an NZSP-based composite electrolyte, a flexible bipolar composite electrode (sodium vanadium phosphate positive electrode / AlPET / sodium metal negative electrode), an NZSP-based composite electrolyte, a flexible bipolar composite electrode (sodium vanadium phosphate positive electrode / AlPET / sodium metal negative electrode), an NZSP-based composite electrolyte, and a flexible unipolar composite electrode (sodium vanadium phosphate positive electrode / AlPET) stacked in sequence, and the whole battery is encapsulated with an aluminum-plastic film.

[0027] Please refer to Figure 1As shown in the figure, the present utility model provides a flexible bipolar solid-state sodium battery, which includes a sodium metal negative electrode layer 1, an NZSP-based composite electrolyte layer 2, a plurality of flexible bipolar composite electrodes 5, an NZSP-based composite electrolyte layer 2, a sodium vanadium phosphate positive electrode layer 3, and an aluminum-coated polyethylene terephthalate fabric core layer 4 arranged in sequence from top to bottom. An NZSP-based composite electrolyte layer 2 is provided between the flexible bipolar composite electrode 5 and the flexible bipolar composite electrode 5. The flexible bipolar composite electrode 5 includes a sodium vanadium phosphate positive electrode layer 3, an aluminum-coated polyethylene terephthalate fabric core layer 4, and a sodium metal negative electrode layer 1 arranged in sequence from top to bottom. Preferably, the number of the flexible bipolar composite electrodes 5 is 2-6, the thickness of the sodium metal negative electrode layer 1 is 20-50 um, the thickness of the NZSP-based composite electrolyte layer 2 is 50-100 um, the thickness of the sodium vanadium phosphate positive electrode layer 3 is 100-200 um, and the thickness of the aluminum-coated polyethylene terephthalate fabric core layer 4 is 20-50 um. The nickel in the nickel-coated polyethylene terephthalate fabric (NiPET) is replaced with aluminum, which improves the electrochemical stability to metallic sodium and reduces the cost. The battery is encapsulated with an aluminum-plastic film. The solid-state sodium battery monomers are connected in series inside, and the voltage is 3.4×(3~7)=10.2~23.5V vs Na+ / Na, reducing ineffective encapsulation and improving the energy density. The aluminum coating will not alloy with sodium, reducing the interfacial impedance and improving the rate and cycle performance of the solid-state sodium battery. The entire solid-state sodium battery has good flexibility and can be applied to wearable electronic devices. Example

[0028] A flexible bipolar solid-state sodium battery described in this embodiment includes a sodium metal negative electrode 1 with a thickness of 20-50 um; an NZSP-based composite electrolyte 2 with a thickness of 50-100 um, which is composed of 80% polyethylene oxide (PEO), 8% sodium salt (NaTFSI), and 12% NZSP (Na3Zr2Si2PO 12 ). A sodium vanadium phosphate positive electrode 3 with a thickness of 100-200 um, which is composed of 80% sodium vanadium phosphate (Na3V2(PO4)3), 10% conductive carbon black, and 10% binder (PVdF). An aluminum-coated polyethylene terephthalate fabric core layer (AlPET) 4 with a thickness of 20-50 um. Among them, 1, 3, and 4 form a flexible bipolar composite electrode, and the entire battery cell monomer is composed of 3 (sodium vanadium phosphate positive electrode || sodium negative electrode) batteries connected in series.

[0029] Although the embodiments of the present utility model have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present utility model. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present utility model is not limited to the specific details and the examples shown and described herein.

Claims

1. A flexible bipolar solid-state sodium battery, characterized in that: It includes a sodium metal negative electrode layer (1) arranged successively from top to bottom, an NZSP-based composite electrolyte layer (2), a plurality of flexible bipolar composite electrodes (5), an NZSP-based composite electrolyte layer (2), a sodium vanadium phosphate positive electrode layer (3), and an aluminum-coated polyethylene terephthalate fabric core layer (4). An NZSP-based composite electrolyte layer (2) is provided between the flexible bipolar composite electrode (5) and the flexible bipolar composite electrode (5). The flexible bipolar composite electrode (5) includes a sodium vanadium phosphate positive electrode layer (3), an aluminum-coated polyethylene terephthalate fabric core layer (4), and a sodium metal negative electrode layer (1) arranged successively from top to bottom.

2. The flexible bipolar solid-state sodium battery according to claim 1, wherein: The number of the flexible bipolar composite electrodes (5) is 2 - 6.

3. The flexible bipolar solid-state sodium battery according to claim 1, characterized in that: The thickness of the sodium metal negative electrode layer (1) is 20 - 50 um.

4. A flexible bipolar solid-state sodium battery according to claim 1, characterized in that: The thickness of the NZSP-based composite electrolyte layer (2) is 50 - 100 um.

5. A flexible bipolar solid-state sodium battery according to claim 1, wherein: The thickness of the sodium vanadium phosphate positive electrode layer (3) is 100 - 200 um.

6. The flexible bipolar solid-state sodium battery according to claim 1, characterized in that: The thickness of the aluminum-coated polyethylene terephthalate fabric core layer (4) is 20 - 50 um.

7. A flexible bipolar solid-state sodium battery according to claim 1, characterized in that: The battery is encapsulated with an aluminum-plastic film.

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