Solid sodium ion pole group, preparation method thereof and battery

Abstract

The invention relates to the technical field of batteries, in particular to a solid-state sodium ion pole group, a preparation method thereof and a battery. The pole group comprises a positive pole piece and a negative pole composite piece, the positive pole piece comprises a positive pole current collector and an active material coating of a sodium ion positive pole material, the negative pole composite piece comprises a negative pole current collector and a solid electrolyte membrane, multi-component alloy is prepared on the surface of the negative pole current collector, and the solid electrolyte membrane is coated on the surface of the negative pole current collector; and the positive plates and the negative composite plates are alternately stacked to form a pole group. When the solid electrolyte membrane is applied, the multi-component alloy can effectively improve the adhesion stability of the solid electrolyte membrane on the negative electrode current collector while improving the negative electrode capacitance and the battery energy density, namely, the membrane forming stability of the solid electrolyte membrane is improved. According to the solid-state sodium ion electrode group disclosed by the invention, the technical effects of high energy density, high safety and long cycle life are realized by optimizing the electrode material and the structural design.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a solid-state sodium ion electrode group, a preparation method thereof, and a battery. Background Art

[0002] With the growing global demand for clean energy, sodium-ion batteries, as a new type of battery technology, have attracted widespread attention due to their advantages such as abundant resources, low cost, and high safety. The hard carbon and soft carbon negative electrode materials currently widely used are limited by the inherent properties of carbon-based materials, and their theoretical capacity is generally low, which seriously restricts the room for improvement in battery energy density. Although the metal negative electrode has a high theoretical capacity, the volume expansion effect generated during the repeated insertion and extraction of sodium causes the electrode structure to pulverize, resulting in deterioration of cycle stability, and then a gradual decrease in capacity. Therefore, how to improve the capacity of sodium-ion batteries has become a key research direction to break through the barriers to the industrialization of sodium-ion batteries. Summary of the Invention

[0003] In view of this, the present application provides a solid-state battery and prepares a new type of negative electrode composite sheet that can effectively improve the capacitance and battery energy density.

[0004] In a first aspect, the present application provides a solid-state sodium ion electrode group, comprising a plurality of positive electrode sheets and a plurality of negative electrode composite sheets; each of the positive electrode sheets comprises a positive electrode current collector and an active material coating, the active material coating is a sodium ion positive electrode material, and the active material coating is coated on the surface of the positive electrode current collector; each of the negative electrode composite sheets comprises a negative electrode current collector and a solid electrolyte membrane, a multi-element alloy is prepared on the surface of the negative electrode current collector, and the solid electrolyte membrane is coated on the surface of the negative electrode current collector; the positive electrode sheets and the negative electrode composite sheets are alternately stacked to form an electrode group.

[0005] In combination with the first aspect, in one possible implementation, the negative electrode current collector is made of copper or aluminum, the multi-component alloy includes an active phase and an inert phase, the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element.

[0006] In combination with the first aspect, in one possible implementation, the active phase includes one or more of the following elements: Pb, Bi, Si, Ge, Sn, Sb and P; the inert phase includes one or more of the following elements: Fe, Co, Ni, V, S and C.

[0007] In combination with the first aspect, in a possible implementation, the thickness of the negative electrode current collector is any value between 5 μm and 10 μm, and the thickness of the solid electrolyte membrane is any value between 3 μm and 8 μm.

[0008] In combination with the first aspect, in a possible implementation, the positive electrode sheet includes a positive electrode tab, which is disposed on the positive electrode current collector; the negative electrode composite sheet includes a negative electrode tab, which is disposed on the negative electrode current collector.

[0009] In combination with the first aspect, in a possible implementation, it further includes: an insulating film covering the electrode group composed of the alternating stacking of the positive electrode sheets and the negative electrode composite sheets; and a battery case for accommodating the positive electrode sheets, the negative electrode composite sheets and the insulating film.

[0010] In a second aspect, the present application provides a preparation method for the aforementioned solid-state sodium ion electrode group, the method comprising: coating an active material coating on a positive electrode current collector to form a positive electrode sheet; depositing a multi-element alloy on the surface of a negative electrode current collector by an electrochemical deposition method to obtain a sodium storage alloy negative electrode; rolling and corona treating the sodium storage alloy negative electrode; coating an aqueous slurry containing a solid electrolyte on the surface of the sodium storage alloy negative electrode to obtain a negative electrode composite; curing the aqueous slurry on the surface of the negative electrode composite by a drying process to form a solid electrolyte film; rolling the negative electrode composite at a preset temperature to form a negative electrode composite sheet; and alternately stacking the positive electrode sheet and the negative electrode composite sheet to form an electrode group.

[0011] In combination with the second aspect, in one possible implementation, the multi-component alloy includes an active phase and an inert phase, the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element; the drying temperature of the drying process is 60°C~80°C; the thickness of the solid electrolyte membrane is 5μm~10μm; and the preset temperature is 80°C~120°C.

[0012] In combination with the second aspect, in a possible implementation, after the positive electrode sheets and the negative electrode composite sheets are alternately stacked to form an electrode group, the method further includes: hot pressing the electrode group at 1 MPa and 80° C. for 3 min to 8 min; and wrapping an insulating film around the electrode group.

[0013] In a third aspect, the present application provides a battery comprising the aforementioned solid-state sodium ion electrode group.

[0014] When the present application is used, a sodium-storage alloy negative electrode is formed by preparing a multi-element alloy on the negative electrode current collector, and then a solid electrolyte membrane is coated on the sodium-storage alloy negative electrode to form a negative electrode composite sheet. The non-metallic or metallic elements of the multi-element alloy of the sodium-storage alloy negative electrode have the ability to combine with sodium to form an alloy. A single atom in the sodium-storage alloy negative electrode can combine with one or more sodium atoms, thereby increasing the theoretical gram capacity of the sodium-storage alloy negative electrode, thereby increasing the negative electrode capacitance and battery energy density of the composite negative electrode sheet of the present application. In addition, the negative electrode composite sheet integrated with the solid electrolyte membrane replaces the diaphragm and electrolyte, saving the diaphragm and electrolyte in the traditional battery structure, simplifying the battery manufacturing process, and facilitating large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Shown is a schematic structural diagram of a positive electrode sheet provided in one embodiment of the present application.

[0016] Figure 2 Shown is a schematic structural diagram of a negative electrode composite sheet provided in one embodiment of the present application.

[0017] Figure 3 The figure shows a schematic structural diagram of an electrode group formed by alternating stacking of positive electrode sheets and negative electrode composite sheets provided in one embodiment of the present application.

[0018] Figure 4 Shown is an enlarged schematic side view of the positive electrode sheet provided in another embodiment of the present application.

[0019] Figure 5 Shown is an enlarged schematic side view of the negative electrode composite sheet provided in another embodiment of the present application.

[0020] Figure 6 Shown is a schematic structural diagram of the positive electrode sheet provided in one embodiment of the present application after cutting out the blank area.

[0021] Figure 7 Shown is a schematic structural diagram of the negative electrode composite sheet provided in one embodiment of the present application after cutting out the blank area.

[0022] Figure 8 FIG2 is a schematic diagram showing the steps of a method for preparing a solid-state sodium ion electrode group provided in one embodiment of the present application.

[0023] Figure 9 FIG2 is a schematic diagram showing the steps of a method for preparing a solid-state sodium ion electrode group provided in another embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0025] Figure 1 Shown is a schematic structural diagram of a positive electrode sheet provided in one embodiment of the present application. Figure 2 Shown is a schematic structural diagram of a negative electrode composite sheet provided in one embodiment of the present application. Figure 3 The figure shows a schematic structural diagram of an electrode group formed by alternating stacking of positive electrode sheets and negative electrode composite sheets provided in one embodiment of the present application. Figure 4 Shown is an enlarged schematic side view of the positive electrode sheet provided in another embodiment of the present application. Figure 5 The figure shows an enlarged side view of the negative electrode composite sheet provided in another embodiment of the present application. The present application provides a solid sodium ion electrode group, such as Figure 1 、 2 As shown in Figures 3, 4, and 5, the solid-state sodium ion electrode group includes a positive electrode sheet 1 and a negative electrode composite sheet 2. The positive electrode sheet 1 includes a positive electrode current collector 101 and an active material coating 102. The active material coating 102 is a sodium ion positive electrode material and is coated on the surface of the positive electrode current collector 101. The negative electrode composite sheet 2 includes a negative electrode current collector 201 and a solid electrolyte membrane 202. A multi-element alloy is prepared on the surface of the negative electrode current collector 201, and the solid electrolyte membrane 202 is coated on the surface of the negative electrode current collector 201. The positive electrode sheets 1 and the negative electrode composite sheets 2 are alternately stacked to form an electrode group.

[0026] In this embodiment, a sodium-storage alloy negative electrode is formed by preparing a multi-element alloy on the negative electrode current collector 201, and then a solid electrolyte membrane 202 is coated on the sodium-storage alloy negative electrode to form a negative electrode composite sheet 2. The non-metallic or metallic elements in the multi-element alloy of the sodium-storage alloy negative electrode have the ability to combine with sodium to form an alloy. A single atom in the sodium-storage alloy negative electrode can combine with one or more sodium atoms, allowing the sodium-storage alloy negative electrode to exhibit a high theoretical gram capacity. Its theoretical gram capacity is higher than that of hard carbon and soft carbon negative electrode materials. Therefore, the composite negative electrode sheet 2 of this application improves the negative electrode capacitance and battery energy density. In addition, the negative electrode composite sheet 2 integrated with the solid electrolyte membrane 202 replaces the separator and electrolyte, saving the separator and electrolyte in the traditional battery structure. The alternating stacking of the positive electrode sheet 1 and the negative electrode composite sheet 2 can form a battery electrode group, simplifying the battery manufacturing process and facilitating large-scale production.

[0027] Specifically, the selected materials for the sodium ion positive electrode material include one or more of the following materials: oxide positive electrode materials, polyanion positive electrode materials, Prussian blue positive electrode materials, and organic positive electrode materials.

[0028] In one embodiment, the multi-component alloy includes an active phase and an inert phase, the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element. When this embodiment is applied, the active phase (metal element and / or non-metal element) in the multi-component alloy provides the storage and release capacity of sodium ions, thereby enhancing the capacity and energy density of the battery. The inert phase (transition metal element and / or non-metal element) can alleviate the changes in the active material during the charge and discharge process, improve the structural stability and cycle life of the electrode, and can reduce the side reactions of the electrode material during the cycle process, thereby improving the safety and reliability of the battery. The synergistic effect of the active phase and the inert phase improves the interfacial compatibility between the electrode and the electrolyte, reduces the interfacial resistance, and improves the charge and discharge efficiency of the battery.

[0029] Specifically, the active phase includes one or more of the following elements: Pb, Bi, Si, Ge, Sn, Sb, and P; the inert phase includes one or more of the following elements: Fe, Co, Ni, V, S, and C. These active phase elements possess catalytic activity or chemical responsiveness. For example, Sn and Sb can serve as high-capacity anode materials in batteries, P and Si can be used as active components in batteries, and Bi and Pb excel in specific catalytic reactions (such as electrochemical reduction). These inert phase elements provide mechanical strength and thermal stability. For example, V enhances corrosion resistance, while S and C (including graphite or sulfides) improve conductivity or lubricity, thereby supporting the structural integrity of the active phase. The inert phase's high-temperature and corrosion resistance protects the active phase from degradation during reactions, preventing material pulverization or failure, significantly extending its service life, especially in high-temperature or corrosive environments. The active phase's high catalytic activity, combined with its conductivity, accelerates electron transport, reduces reaction activation energy, and improves energy conversion efficiency (e.g., battery charge and discharge or catalytic reaction rate).

[0030] Preferably, the multi-component alloy is Sn@C or Sb@C.

[0031] In one embodiment, the negative electrode current collector 201 is made of copper or aluminum. In this embodiment, copper and aluminum have excellent electrical conductivity, which can effectively reduce the internal resistance of the battery and improve the charge and discharge efficiency.

[0032] Specifically, the thickness of the negative electrode current collector 201 is any value between 5μm and 10μm, and the thickness of the solid electrolyte membrane 202 is any value between 3μm and 8μm. This thin design reduces the proportion of inactive materials and improves the energy density of the electrode group. The thinner negative electrode current collector and solid electrolyte membrane shorten the transmission path of ions and electrons, reduce the internal resistance of the electrode group, and thus improve the charge and discharge efficiency and rate performance. In addition, the thinned current collector and electrolyte membrane facilitate the alternating stacking of a large number of positive and negative electrode composite sheets, thereby increasing the capacitance of the electrode group.

[0033] In a specific embodiment, the thickness of the negative electrode current collector 201 is 5 μm, and the thickness of the solid electrolyte membrane 202 is 3 μm.

[0034] In a specific embodiment, the thickness of the negative electrode current collector 201 is 8 μm, and the thickness of the solid electrolyte membrane 202 is 5 μm.

[0035] In a specific embodiment, the thickness of the negative electrode current collector 201 is 10 μm, and the thickness of the solid electrolyte membrane 202 is 8 μm.

[0036] Figure 6 Shown is a schematic structural diagram of the positive electrode sheet provided in one embodiment of the present application after cutting out the blank area. Figure 7 The figure shows the structure of the negative electrode composite sheet provided by one embodiment of the present application after the blank area is cut out. Figure 6 、 7 As shown, the positive electrode sheet 1 includes a positive electrode tab 103, which is arranged on the side of the positive electrode current collector 101 for electrical connection from the side of the current collector. The negative electrode composite sheet 2 includes a negative electrode tab 203, which is arranged on the side of the negative electrode current collector 201 for electrical connection from the side of the current collector.

[0037] In one embodiment, if Figure 3 As shown, the solid-state sodium-ion electrode group also includes an insulating film 3 and a battery housing. The insulating film 3 is coated on the surrounding surface of the electrode group, which is composed of alternating positive electrode sheets 1 and negative electrode composite sheets 2. The battery housing is used to accommodate the positive electrode sheets 1, negative electrode composite sheets 2, and insulating film 3. When used in this embodiment, the insulating film 3 is coated on the surrounding surface of the electrode group, which can effectively prevent the electrode group from direct contact with the outside world or short circuit, thereby avoiding thermal runaway or safety issues caused by short circuit. The coating of the insulating film 3 also provides additional mechanical support for the electrode group, enhancing the overall structural stability, reducing the internal stress caused by volume changes during the battery charging and discharging process, and extending the battery's cycle life. The battery housing is used to accommodate the electrode group and the insulating film 3, which can effectively isolate the external environment (such as moisture, oxygen, or pollutants) from corroding the internal materials of the battery, thereby improving the reliability and durability of the battery.

[0038] Figure 8The figure shows a schematic diagram of the steps of a method for preparing a solid sodium ion electrode group provided in one embodiment of the present application. The present application also provides a method for preparing a solid sodium ion electrode group, such as Figure 8 As shown, the method includes: Step 110 : coating an active material coating 102 on the positive electrode current collector 101 to produce a positive electrode sheet 1 .

[0039] Step 120 : Clamp the blank areas on both sides of the negative electrode current collector 201 with the equipment tooling, and place the negative electrode current collector 201 into the electrochemical deposition equipment.

[0040] Step 130 : depositing a multi-element alloy on the surface of the negative electrode current collector 201 by electrochemical deposition to obtain a sodium storage alloy negative electrode.

[0041] Step 140: Roll-press and corona-treat the sodium storage alloy negative electrode.

[0042] Step 150: Coat the surface of the sodium storage alloy negative electrode with an aqueous slurry containing a solid electrolyte to obtain a negative electrode composite.

[0043] Step 160: The aqueous slurry is solidified on the surface of the negative electrode composite through a drying process to form a solid electrolyte film 202. Step 140, combined with roller pressing and corona treatment, smoothes the surface of the negative electrode current collector 201, where the multi-element alloy is deposited. This improves the adhesion stability and film uniformity of the solid electrolyte film 202, effectively optimizing the electrochemical performance of the negative electrode composite sheet. The aqueous slurry coating and drying process allows for the formation of a uniform solid electrolyte film 202 on the surface of the negative electrode current collector 201, improving the interfacial contact between the electrode and the electrolyte and reducing interfacial impedance.

[0044] Step 170 : Roll-press the negative electrode composite at a preset temperature to form a negative electrode composite sheet 2 . Also, cut the blank areas on both sides of the negative electrode current collector 201 to form negative electrode tabs 203 , and cut the blank areas on both sides of the positive electrode current collector 101 to form positive electrode tabs 103 .

[0045] Step 180: Alternately stack the positive electrode sheets 1 and the negative electrode composite sheets 2 to form an electrode assembly. The preset temperature roll pressing and alternating stacking process ensures close contact between the positive electrode sheets 1 and the negative electrode composite sheets 2, thereby improving the structural consistency and electrochemical performance of the electrode assembly.

[0046] The electrode assembly produced in this embodiment has the following technical effects: a sodium-storage alloy negative electrode is formed by preparing a multi-element alloy on the negative electrode current collector 201, and then a solid electrolyte membrane 202 is coated on the sodium-storage alloy negative electrode to form a negative electrode composite sheet 2. The non-metallic or metallic elements of the multi-element alloy of the sodium-storage alloy negative electrode have the ability to combine with sodium to form an alloy. A single atom in the sodium-storage alloy negative electrode can combine with one or more sodium atoms, allowing the sodium-storage alloy negative electrode to exhibit a high theoretical gram capacity. Its theoretical gram capacity is higher than that of hard carbon and soft carbon negative electrode materials. Therefore, the composite negative electrode sheet 2 of this application improves the negative electrode capacitance and battery energy density. In addition, the negative electrode composite sheet 2 integrated with the solid electrolyte membrane 202 replaces the separator and electrolyte, saving the separator and electrolyte in the traditional battery structure. The battery electrode assembly can be formed by alternating the positive electrode sheet 1 and the negative electrode composite sheet 2, simplifying the battery manufacturing process and facilitating large-scale production.

[0047] In one embodiment, the multi-component alloy includes an active phase and an inert phase, the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element; the drying temperature of the drying process is 60°C~80°C; the thickness of the solid electrolyte membrane 202 is 5μm~10μm; and the preset temperature is 80°C~120°C.

[0048] Figure 9 FIG. 1 is a schematic diagram of the steps of a method for preparing a solid-state sodium ion electrode group according to another embodiment of the present application. Specifically, step 130 includes: Step 131 : preparing an active phase multi-component alloy and an inert phase multi-component alloy on the surface of the negative electrode current collector 201 .

[0049] In this step, the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element.

[0050] Step 160 includes: Step 161: Dry the aqueous slurry at 60°C to 80°C to solidify it into a solid electrolyte membrane 202 with a thickness of 5 μm to 10 μm. The drying process temperature can be set to any value between 60°C and 80°C, or fluctuate within the range of 60°C to 80°C.

[0051] Step 170 includes: Step 171 : Roll-pressing the negative electrode current collector 201 at 80° C. to 120° C. to form a negative electrode composite sheet 2 . The rolling temperature can be set to any value between 80° C. and 120° C., or fluctuate within the range of 80° C. to 120° C.

[0052] After step 180, the method for preparing the solid-state sodium ion electrode group further includes: Step 190: Hot-press the electrode assembly at 1 MPa and 80° C. for 3 to 8 minutes. This allows the positive electrode sheet 1 and the negative electrode composite sheet 2 to adhere more closely to each other, further reducing the space occupied by the electrode assembly and improving the structural consistency and electrochemical performance of the electrode assembly.

[0053] Step 200: Coat the electrode assembly with an insulating film 3. Coating the electrode assembly with the insulating film 3 effectively prevents direct contact with the outside world or short circuits, thereby preventing thermal runaway and other safety issues caused by short circuits. The insulating film 3 also provides additional mechanical support for the electrode assembly, enhancing overall structural stability, reducing internal stress caused by volume changes during charge and discharge, and extending the battery's cycle life.

[0054] The battery housing is then assembled to accommodate the electrode group and the insulating film 3, which can effectively isolate the external environment (such as moisture, oxygen or pollutants) from corroding the internal materials of the battery, thereby improving the reliability and durability of the battery.

[0055] The present application also provides a battery, which includes the aforementioned solid-state sodium ion electrode group.

[0056] The basic principles of this application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to being implemented using the above specific details.

[0057] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0058] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0059] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be applied in the widest sense consistent with the principles and novel features of the present invention.

[0060] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A solid sodium ion electrode group, characterized in that It comprises a plurality of positive electrode sheets (1) and a plurality of negative electrode composite sheets (2); Each of the positive electrode sheets (1) comprises a positive electrode current collector (101) and an active material coating (102), wherein the active material coating (102) is a sodium ion positive electrode material, and the active material coating (102) is coated on the surface of the positive electrode current collector (101); Each of the negative electrode composite sheets (2) comprises a negative electrode current collector (201) and a solid electrolyte membrane (202), wherein a multi-element alloy is prepared on the surface of the negative electrode current collector (201), and the solid electrolyte membrane (202) is coated on the surface of the negative electrode current collector (201); The positive electrode sheets (1) and the negative electrode composite sheets (2) are alternately stacked to form an electrode group.

2. The solid-state sodium ion electrode group according to claim 1, characterized in that The negative electrode current collector (201) is made of copper or aluminum; The multi-component alloy includes an active phase and an inert phase, the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element.

3. The solid sodium ion electrode group according to claim 2, characterized in that The active phase includes one or more of the following elements: Pb, Bi, Si, Ge, Sn, Sb and P; The inert phase includes one or more of the following elements: Fe, Co, Ni, V, S and C.

4. The solid-state sodium ion electrode group according to claim 1, characterized in that The thickness of the negative electrode current collector (201) is any value between 5 μm and 10 μm, and the thickness of the solid electrolyte membrane (202) is any value between 3 μm and 8 μm.

5. The solid-state sodium ion electrode group according to claim 1, characterized in that: The positive electrode sheet (1) comprises a positive electrode tab (103), and the positive electrode tab (103) is arranged on the positive electrode current collector (101); the negative electrode composite sheet (2) comprises a negative electrode tab (203), and the negative electrode tab (203) is arranged on the negative electrode current collector (201).

6. The solid-state sodium ion electrode group according to claim 1, characterized in that: Also includes: An insulating film (3) covering the electrode group formed by alternately stacking the positive electrode sheets (1) and the negative electrode composite sheets (2); as well as A battery housing is used to accommodate the positive electrode sheet (1), the negative electrode composite sheet (2) and the insulating film (3).

7. A method for preparing a solid sodium ion electrode group according to any one of claims 1 to 6, characterized in that: The method comprises: Coating an active material coating (102) on a positive electrode current collector (101) to form a positive electrode sheet (1); A multi-element alloy is deposited on the surface of the negative electrode current collector (201) by electrochemical deposition to obtain a sodium storage alloy negative electrode; performing roller pressing and corona treatment on the sodium storage alloy negative electrode; coating an aqueous slurry containing a solid electrolyte on the surface of the sodium storage alloy negative electrode to obtain a negative electrode composite; solidifying the aqueous slurry on the surface of the negative electrode composite through a drying process to form a solid electrolyte membrane (202); Rolling the negative electrode composite at a preset temperature to form a negative electrode composite sheet (2); The positive electrode sheets (1) and the negative electrode composite sheets (2) are alternately stacked to form an electrode group.

8. The method for preparing a solid sodium ion electrode group according to claim 7, characterized in that: The multi-component alloy includes an active phase and an inert phase, wherein the active phase is a metal element and / or a non-metal element, and the inert phase is a transition metal element and / or a non-metal element; The drying temperature of the drying process is 60°C to 80°C; The thickness of the solid electrolyte membrane (202) is 5 μm to 10 μm; The preset temperature is 80°C to 120°C.

9. The method for preparing a solid sodium ion electrode group according to claim 7, wherein: After the positive electrode sheets (1) and the negative electrode composite sheets (2) are alternately stacked to form an electrode group, the method further comprises: Hot pressing the electrode assembly at 1 MPa and 80° C. for 3 to 8 minutes; and An insulating film (3) is wrapped around the electrode group.

10. A battery, characterized in that: include: The solid sodium ion electrode group according to any one of claims 1 to 6.

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