Sodium-ion battery built-in thermoelectric characterization test model and preparation method thereof, and application of thermoelectric characterization test adopting test model

Abstract

The invention provides a sodium ion battery built-in thermoelectric characterization test model and a preparation method thereof, and application of a thermoelectric characterization test using the test model. The sodium ion battery built-in thermoelectric characterization test model comprises a positive plate, an insulator and a thermoelectric characterization measurement body, the positive plate is provided with at least one notch, the thermoelectric characterization measurement body is accommodated in the notch, the thermoelectric characterization measurement body is connected to the positive plate through the insulator, and the thermoelectric characterization measurement body and the positive plate are arranged at an interval. The thermoelectric characterization measuring body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch. The sodium ion battery is internally provided with the thermoelectric characterization test model, so that the accuracy of the electrothermal characterization of the sodium ion battery can be well improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to an in-sodium-ion-battery thermoelectric characterization test model, a preparation method thereof, and an application of thermoelectric characterization test using the test model. Background Art

[0002] Due to the low-cost advantage of sodium-ion batteries, they have broad prospects. In order to better study the electrochemical performance of sodium-ion batteries, electrochemical three-electrode systems are usually used. The conventional method for characterizing the in-built electrochemical three-electrode of a general sodium-ion battery is to use an enameled wire and coat sodium on the exposed copper wire of the enameled wire, as Figure 1 shown; while the conventional method for characterizing the external electrochemical three-electrode of a general sodium-ion battery is to coat sodium on a copper wire, wrap a sodium sheet around a copper wire, and weld sodium vanadate phosphate to a copper wire, etc. When the reference electrode is placed externally, the distance between the reference electrode and the electrode sheet is relatively far, resulting in a large bias in potential measurement. When the reference electrode is placed internally, the distance between the reference electrode and the electrode sheet is relatively close, and the bias in potential measurement can be ignored. That is, the accuracy of potential characterization is relatively poor for the external placement compared to the internal placement. However, when the reference electrode is inside the core, it will hinder the migration of sodium ions, leading to sodium deposition on the positive electrode side of the reference electrode and causing the potential characterization of the reference electrode to be inaccurate;

[0003] In order to better study the thermal performance of sodium-ion batteries, thermocouples are usually used. The conventional method for thermally characterizing a general sodium-ion battery is to attach thermocouples to different positions on the surface of the battery. However, the failure location of sodium-ion batteries often occurs inside the battery core, and the temperature characterization on the outside of the sodium-ion battery has a delay and relatively poor temperature characterization accuracy. Summary of the Invention

[0004] An object of the present invention is to overcome the deficiencies in the prior art and provide an in-sodium-ion-battery thermoelectric characterization test model, a preparation method thereof, and an application of thermoelectric characterization test using the test model, which can better improve the accuracy of electrothermal characterization of sodium-ion batteries.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] An in-sodium-ion-battery thermoelectric characterization test model includes a positive electrode sheet, an insulator, and a thermoelectric characterization measurement body. The positive electrode sheet is provided with at least one notch. The thermoelectric characterization measurement body is accommodated in the notch, and the thermoelectric characterization measurement body is connected to the positive electrode sheet through the insulator, and the thermoelectric characterization measurement body is spaced apart from the positive electrode sheet;

[0007] The thermoelectric characterization measurement body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch.

[0008] In one embodiment, the number of the notches is one, and the thermoelectric characterization measurement body is a reference electrode; or,

[0009] the number of the notches is one, and the thermoelectric characterization measurement body is a thermocouple; or,

[0010] the number of the notches is one, and the thermoelectric characterization measurement body includes a reference electrode and a thermocouple. The reference electrode and the thermocouple are spaced and accommodated at the notch, and both the reference electrode and the thermocouple are connected to the positive electrode plate through the insulator; or,

[0011] the number of the notches is two, and the two notches are spaced on the positive electrode plate. The thermoelectric characterization measurement body includes a reference electrode and a thermocouple. The reference electrode is accommodated in one of the notches, and the reference electrode is connected to the positive electrode plate through the insulator. The thermocouple is accommodated in the other notch, and the thermocouple is connected to the positive electrode plate through the insulator; or,

[0012] the number of the notches is multiple, and the multiple notches are spaced on the positive electrode plate. The thermoelectric characterization measurement body includes a reference electrode and a thermocouple. The reference electrode is accommodated in at least one of the notches, and the reference electrode is connected to the positive electrode plate through the insulator. The thermocouple is accommodated in at least another notch, and the thermocouple is connected to the positive electrode plate through the insulator; or,

[0013] the number of the notches is two or more, and the two or more notches are spaced on the positive electrode plate. The thermoelectric characterization measurement body is a reference electrode, and a reference electrode is provided at each notch. The reference electrode at each notch is connected to the positive electrode plate through the insulator; or,

[0014] the number of the notches is two or more, and the two or more notches are spaced on the positive electrode plate. The thermoelectric characterization measurement body is a thermocouple, and a thermocouple is provided at each notch. The thermocouple at each notch is connected to the positive electrode plate through the insulator. Thermoelectric characterization measurement body Thermoelectric characterization measurement body Thermoelectric characterization measurement body Thermoelectric characterization measurement body

[0015] In one embodiment, the reference electrode is a sodium vanadium phosphate reference electrode.

[0016] In one embodiment, the state of charge of the sodium vanadium phosphate reference electrode is 5% SOC to 95% SOC.

[0017] In one embodiment, the diameter of the sodium vanadium phosphate reference electrode is 50 nm to 300 nm.

[0018] In one embodiment, the thermocouple is a K-type ultra-fine temperature measurement wire or a T-type ultra-fine temperature measurement wire.

[0019] In one embodiment, the diameter of the thermocouple is 50 μm to 300 μm.

[0020] In one embodiment, a coating layer is attached to the surface of the thermocouple, and the coating layer is a thermally conductive adhesive layer or a paraffin oil layer.

[0021] In one embodiment, the thickness of the coating layer is 5 μm to 100 μm.

[0022] In one embodiment, the thermally conductive adhesive layer includes a thermally conductive filler and a binder.

[0023] In one embodiment, the paraffin oil is selected from one of paraffin oils with different melting temperatures.

[0024] A preparation method of an in-sodium-ion-battery thermoelectric characterization test model, which is used to prepare the in-sodium-ion-battery thermoelectric characterization test model described in any one of the above embodiments. The preparation method of the in-sodium-ion-battery thermoelectric characterization test model includes the following steps:

[0025] Obtain a positive electrode sheet;

[0026] Perform a cutting operation on the positive electrode sheet so that at least one notch is formed on the positive electrode sheet;

[0027] Use an insulator to assemble the notch so that a thermoelectric characterization measurement body is accommodated in the notch through the insulator, and the thermoelectric characterization measurement body is spaced apart from the positive electrode sheet. Among them, the thermoelectric characterization measurement body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch.

[0028] An application of thermoelectric characterization test using this test model, applying the in-sodium-ion-battery thermoelectric characterization test model described in any one of the above embodiments to the potential measurement of the in-sodium-ion-battery three-electrode and the temperature measurement of the in-sodium-ion-battery thermocouple.

[0029] Compared with the prior art, the present invention has at least the following advantages:

[0030] The sodium-ion battery of the present invention is built with a thermoelectric characterization test model, which forms a notch on the positive electrode sheet. The thermoelectric characterization measurement body is placed in the notch, and the thermoelectric characterization measurement body is insulated from the positive electrode sheet through an insulator and does not come into contact with it. In this way, when the thermoelectric characterization measurement body includes a reference electrode, the reference electrode is built inside the winding core, and the positive electrode sheet corresponding to the reference electrode forms a notch, which will not cooperate with the negative electrode sheet to form a sodium-ion migration channel. Furthermore, the situation where the reference electrode hinders the migration of sodium ions and causes sodium deposition on the positive side of the reference electrode will not occur, that is, the problem of inaccurate potential characterization of the reference electrode is effectively avoided, and the accuracy of the potential characterization of the thermoelectric characterization test model built in the sodium-ion battery is improved; when the thermoelectric characterization measurement body includes a thermocouple, the thermocouple is built inside the winding core to directly characterize and measure the temperature inside the winding core, effectively avoiding delay and improving the accuracy of the temperature characterization of the thermoelectric characterization test model built in the sodium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of the positive electrode sheet in the built-in three-electrode electrochemistry of a conventional sodium-ion battery;

[0033] Figure 2 It is a schematic structural diagram of the thermoelectric characterization test model built in the sodium-ion battery according to an embodiment of the present invention;

[0034] Figure 3 It is a schematic structural diagram of the thermoelectric characterization test model built in the sodium-ion battery according to another embodiment of the present invention;

[0035] Figure 4 It is a flowchart of the preparation method of the thermoelectric characterization test model built in the sodium-ion battery according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention 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 invention more thorough and comprehensive.

[0037] It should be noted that when an element is referred to as "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of this invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0039] This application provides a built-in thermoelectric characterization test model for a sodium-ion battery. The above-mentioned built-in thermoelectric characterization test model for a sodium-ion battery includes a positive electrode sheet, an insulator and a thermoelectric characterization measurement body. The positive electrode sheet is provided with at least one notch. The thermoelectric characterization measurement body is accommodated in the notch, and the thermoelectric characterization measurement body is connected to the positive electrode sheet through the insulator, and the thermoelectric characterization measurement body is spaced apart from the positive electrode sheet. The thermoelectric characterization measurement body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch.

[0040] For the above-mentioned built-in thermoelectric characterization test model of a sodium-ion battery, a notch is formed on the positive electrode sheet, and the thermoelectric characterization measurement body is accommodated at the notch, and the thermoelectric characterization measurement body is insulated from the positive electrode sheet through the insulator and is not in contact. In this way, when the thermoelectric characterization measurement body includes a reference electrode, the reference electrode is built into the interior of the wound core, and the positive electrode sheet corresponding to the reference electrode forms a notch, which will not cooperate with the negative electrode sheet to form a sodium ion migration channel, and thus the situation where the reference electrode hinders the migration of sodium ions and causes sodium deposition on the positive electrode side of the reference electrode will not occur, that is, the problem of inaccurate potential characterization of the reference electrode is effectively avoided, and the accuracy of potential characterization of the built-in thermoelectric characterization test model of the sodium-ion battery is improved; and when the thermoelectric characterization measurement body includes a thermocouple, the thermocouple is built into the interior of the wound core to directly characterize and measure the temperature inside the wound core, effectively avoiding delay and improving the accuracy of temperature characterization of the built-in thermoelectric characterization test model of the sodium-ion battery.

[0041] To better understand the built-in thermoelectric characterization test model of the sodium-ion battery of this application, the following further explains and illustrates the built-in thermoelectric characterization test model of the sodium-ion battery of this application:

[0042] Please refer to Figure 2 or Figure 3, a thermoelectric characterization test model 10 of a sodium-ion battery in one embodiment includes a positive electrode sheet 100, an insulator 200, and a thermoelectric characterization measurement body. The positive electrode sheet 100 is provided with at least one notch 101. The thermoelectric characterization measurement body is accommodated in the notch 101, and the thermoelectric characterization measurement body is connected to the positive electrode sheet 100 through the insulator 200, and the thermoelectric characterization measurement body is spaced apart from the positive electrode sheet 100. The thermoelectric characterization measurement body is at least one of a reference electrode 300 and a thermocouple 400. The reference electrode 300 and the thermocouple 400 are independently arranged at the notch 101.

[0043] For the above-mentioned thermoelectric characterization test model 10 of the sodium-ion battery, a notch 101 is formed on the positive electrode sheet 100, and the thermoelectric characterization measurement body is accommodated at the notch 101. Moreover, the thermoelectric characterization measurement body is insulated from the positive electrode sheet 100 through the insulator 200 without contact. In this way, when the thermoelectric characterization measurement body includes the reference electrode 300, the reference electrode 300 is built into the inside of the wound core, and the positive electrode sheet 100 corresponding to the reference electrode 300 forms a notch 101, which will not cooperate with the negative electrode sheet to form a sodium-ion migration channel. Furthermore, the situation where the reference electrode 300 hinders the migration of sodium ions and causes sodium deposition on the positive electrode side of the reference electrode 300 will not occur, that is, the problem of inaccurate potential characterization of the reference electrode 300 is effectively avoided, and the accuracy of potential characterization of the thermoelectric characterization test model 10 of the sodium-ion battery is improved; when the thermoelectric characterization measurement body includes the thermocouple 400, the thermocouple 400 is built into the inside of the wound core, directly characterizing and measuring the temperature inside the wound core, effectively avoiding the delay, and improving the accuracy of temperature characterization of the thermoelectric characterization test model 10 of the sodium-ion battery.

[0044] Please refer to Figure 2 or Figure 3 , in one embodiment, one end of the thermoelectric characterization measurement body is electrically connected to the bare copper of the enameled wire 500, and the other end of the enameled wire 500 is located outside the battery. Further, the length of the bare copper is 0.1 cm to 2 cm. Further, if the thermoelectric characterization measurement body is the reference electrode 300, the enameled wire 500 is electrically connected to the reference electrode 300 by welding. If the thermoelectric characterization measurement body is the thermocouple 400, the probe of the thermocouple 400 is equipped with the enameled wire 500, and no additional electrical connection treatment is required. Only the probe needs to be connected through the insulator 200. It can also be understood that the end of the enameled wire 500 located outside the battery is the wiring of the conventional three-electrode structure of the battery, which will not be elaborated here.

[0045] In one embodiment, the insulator is adhesive tape. Further, the adhesive tape is a polyimide high-temperature resistant tape or a polypropylene high-temperature resistant tape, which preferably ensures the stable setting of the thermoelectric characterization measurement body and preferably ensures the stable spaced insulation setting between the thermoelectric characterization measurement body and the positive electrode sheet.

[0046] In one embodiment, the insulator is a separator. Further, the insulator winds around the reference electrode for several turns. Further, the insulator winds around the reference electrode for several turns until the overall thickness does not exceed the thickness of the positive electrode sheet. It can be understood that if the insulator is a separator, when the thermoelectric characterization measurement body is placed in the notch, it is further clamped by the separator that separates the positive electrode sheet and the negative electrode sheet in the wound core, and it can also be clamped by the separator and the negative electrode sheet together. In one embodiment, the width of the notch is greater than the width of the thermoelectric characterization measurement body, which preferably ensures an effective avoidance setting between the thermoelectric characterization measurement body and the positive electrode sheet.

[0047] Please refer to Figure 2 , in one embodiment, the number of notches 101 is one, and the thermoelectric characterization measurement body is the reference electrode 300. Or, please refer to Figure 3 , in another embodiment, the number of notches 101 is one, and the thermoelectric characterization measurement body is the thermocouple 400. Or, in yet another embodiment, the number of notches is one, and the thermoelectric characterization measurement body includes a reference electrode and a thermocouple. The reference electrode and the thermocouple are spaced and placed in the notch, and both the reference electrode and the thermocouple are connected to the positive electrode sheet through the insulator. Or, in yet another embodiment, the number of notches is two, and the two notches are spaced on the positive electrode sheet. The thermoelectric characterization measurement body includes a reference electrode and a thermocouple. The reference electrode is placed in one of the notches, and the reference electrode is connected to the positive electrode sheet through the insulator. The thermocouple is placed in the other notch, and the thermocouple is connected to the positive electrode sheet through the insulator. Or, in yet another embodiment, the number of notches is multiple, and the multiple notches are spaced on the positive electrode sheet. The thermoelectric characterization measurement body includes a reference electrode and a thermocouple. The reference electrode is placed in at least one of the notches, and the reference electrode is connected to the positive electrode sheet through the insulator. The thermocouple is placed in at least another notch, and the thermocouple is connected to the positive electrode sheet through the insulator. Or, in yet another embodiment, the number of notches is two or more, and the two or more notches are spaced on the positive electrode sheet. The thermoelectric characterization measurement body is a reference electrode, and a reference electrode is provided at each notch. The reference electrode at each notch is connected to the positive electrode sheet through the insulator. Or, in yet another embodiment, the number of notches is two or more, and the two or more notches are spaced on the positive electrode sheet. The thermoelectric characterization measurement body is a thermocouple, and a thermocouple is provided at each notch. The thermocouple at each notch is connected to the positive electrode sheet through the insulator. It can be understood that in the wound core, at least one reference electrode can be set separately, at least one thermocouple can be set separately, and in addition, at least one reference electrode and at least one thermocouple can be set simultaneously, which has strong practicability. Thermoelectric characterization measurement body Thermoelectric characterization measurement body Thermoelectric characterization measurement body Thermoelectric characterization measurement body

[0048] In one embodiment, the reference electrode is a sodium vanadium phosphate reference electrode. Further, the state of charge of the sodium vanadium phosphate reference electrode is 5% SOC to 95% SOC. Further, the diameter of the sodium vanadium phosphate reference electrode is 50 nm to 300 nm. It can be understood that for general built-in and external reference electrodes, if sodium metal needs to be set on them, due to the instability of sodium metal itself, in a sodium-ion battery system, it is easy to react with the electrolyte, damage the sodium metal layer, resulting in inaccurate potential characterization of the reference electrode. At the same time, gas is extremely likely to be generated during the reaction of sodium metal with the electrolyte, causing deterioration of the performance of the sodium-ion battery and affecting the long-term potential characterization of the sodium-ion battery. Therefore, the reference electrode is made of sodium vanadium phosphate reference electrode. In this way, in the case of the notch on the positive electrode sheet, that is, on the basis that there is no serious sodium deposition phenomenon when using the sodium vanadium phosphate reference electrode to affect the accuracy of potential characterization, using the sodium vanadium phosphate reference electrode effectively improves the structural stability of the reference electrode in the built-in state, and even has high structural stability at high temperatures, thereby effectively realizing the long-term effectiveness of potential characterization.

[0049] In one embodiment, the thermocouple is a K-type ultra-fine temperature measurement wire or a T-type ultra-fine temperature measurement wire. Further, the diameter of the thermocouple is 50 μm to 300 μm.

[0050] In one embodiment, a coating layer is attached to the surface of the thermocouple, and the coating layer is a thermally conductive adhesive layer or a paraffin oil layer. Further, the thickness of the coating layer is 5 μm to 100 μm. It can be understood that when the thermocouple contacts the electrolyte, it will affect the measurement accuracy of the thermocouple and even cause the thermocouple to fail. Therefore, a coating layer is coated on the surface of the probe of the thermocouple to isolate the probe of the thermocouple from the contact with the electrolyte, that is, the coating layer is coated on the surface of the probe of the thermocouple, effectively improving the protection effect of the thermocouple and the functional stability of the thermocouple. Further, the thickness of the coating layer is 5 μm to 100 μm, which preferably ensures the protection effect. When the coating layer is a thermally conductive adhesive layer, the timeliness and sufficiency of heat conduction of the coating layer are preferably ensured, that is, the timeliness and accuracy of temperature characterization of the thermocouple are improved.

[0051] In one embodiment, the thermally conductive adhesive layer includes a thermally conductive filler and a binder. Further, the thermally conductive filler is at least one of barium oxide, zirconium oxide, silicon oxide, calcium oxide, aluminum oxide, graphite, carbon fiber, and boron nitride. Further, the binder includes at least one of polydimethylsiloxane, polytetrafluoroethylene, polyurethane, epoxy resin, polyethylene, and polyacrylate, preferably ensuring the adhesion stability and heat conduction timeliness and effectiveness of the thermally conductive adhesive layer on the surface of the thermocouple. Further, the mass ratio of the thermally conductive filler to the binder is (1 to 3):(7 to 9).

[0052] In one embodiment, the paraffin oil is selected from paraffin oils with different melting temperatures. It can be understood that the melting point range of paraffin oil is generally between 50°C and 150°C, and the specific range depends on its specific chemical composition and refining process. Paraffin oils with different melting points can be directly purchased on the market. In this application, the specific components and preparation of paraffin oil are not protected, but only the selection and utilization of paraffin oils with different melting temperatures are protected. When the temperature at the notch of the positive electrode sheet reaches the melting point of the selected paraffin oil, the paraffin oil melts, and the thermocouple is exposed and fails. That is, the thermocouple is realized under the specified thermal setting temperature and is applied to the battery for conversion test at a specific temperature.

[0053] In one embodiment, in the upward direction of the length of the positive electrode sheet, the notch is located at the position of 1 / 4 of the total length of the positive electrode sheet, and / or the notch is located at the position of 1 / 2 of the total length of the positive electrode sheet, and / or the notch is located at the position of 3 / 4 of the total length of the positive electrode sheet.

[0054] In one embodiment, in the width direction of the positive electrode sheet, the notch is located at the position of 1 / 4 of the total width of the positive electrode sheet, and / or the notch is located at the position of 1 / 2 of the total width of the positive electrode sheet, and / or the notch is located at the position of 3 / 4 of the total width of the positive electrode sheet.

[0055] This application also provides a preparation method for a built-in thermoelectric characterization test model of a sodium-ion battery, which is used to prepare the built-in thermoelectric characterization test model of a sodium-ion battery in any of the above embodiments. The preparation method of the above-mentioned built-in thermoelectric characterization test model of a sodium-ion battery includes the following steps: obtaining a positive electrode sheet; performing a cutting operation on the positive electrode sheet so that at least one notch is formed on the positive electrode sheet; using an insulator to perform an assembly process on the notch so that a thermoelectric characterization measuring body is accommodated on the notch through the insulator, and the thermoelectric characterization measuring body is spaced apart from the positive electrode sheet, wherein the thermoelectric characterization measuring body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch.

[0056] In the preparation method of the above-mentioned built-in thermoelectric characterization test model of a sodium-ion battery, performing a cutting operation on the positive electrode sheet preferably realizes the effective formation of the notch, and further cooperating with using an insulator to perform an assembly process on the notch effectively realizes the effective fixation of the thermoelectric characterization measuring body on the notch through the insulator, and realizes the effective avoidance and insulation setting of the thermoelectric characterization measuring body and the positive electrode sheet, that is, effectively realizes the preparation of the built-in thermoelectric characterization test model of a sodium-ion battery.

[0057] To better understand the preparation method of the built-in thermoelectric characterization test model of a sodium-ion battery in this application, the following further explains the preparation method of the built-in thermoelectric characterization test model of a sodium-ion battery in this application:

[0058] Please refer to Figure 4, The preparation method of the built-in thermoelectric characterization test model of a sodium-ion battery in one embodiment includes the following steps:

[0059] S100. Obtain a positive electrode sheet;

[0060] S200. Perform a cutting operation on the positive electrode sheet so that at least one notch is formed on the positive electrode sheet. It can be understood that the cutting operation of the positive electrode sheet is performed with scissors, or the cutting operation of the positive electrode sheet is performed using a slicing device for the electrode sheet. This application aims to protect the formation of a notch on the positive electrode sheet, and does not protect the formation of the notch by any tool used.

[0061] S300. Assemble and process the notch with an insulator so that a thermoelectric characterization measuring body is accommodated in the notch through the insulator, and the thermoelectric characterization measuring body is spaced from the positive electrode sheet. Among them, the thermoelectric characterization measuring body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch.

[0062] In the above preparation method of the built-in thermoelectric characterization test model of a sodium-ion battery, the cutting operation on the positive electrode sheet preferably realizes the effective formation of the notch, and further cooperates with the assembly process of the notch with an insulator, effectively realizing the effective fixation of the thermoelectric characterization measuring body on the notch through the insulator, and realizing the effective avoidance and insulation setting between the thermoelectric characterization measuring body and the positive electrode sheet, that is, effectively realizing the preparation of the built-in thermoelectric characterization test model of a sodium-ion battery.

[0063] This application also provides an application of thermoelectric characterization testing using this test model, applying the built-in thermoelectric characterization test model of a sodium-ion battery in any of the above embodiments to the potential measurement of the built-in electrochemical three electrodes of a sodium-ion battery and the temperature measurement of the built-in thermocouple of a sodium-ion battery. Further, please refer to Figure 2 or Figure 3 , In this embodiment, the built-in thermoelectric characterization test model 10 of a sodium-ion battery includes a positive electrode sheet 100, an insulator 200, and a thermoelectric characterization measuring body. The positive electrode sheet 100 is provided with at least one notch 101. The thermoelectric characterization measuring body is accommodated in the notch 101, and the thermoelectric characterization measuring body is connected to the positive electrode sheet 100 through the insulator 200, and the thermoelectric characterization measuring body is spaced from the positive electrode sheet 100. The thermoelectric characterization measuring body is at least one of a reference electrode 300 and a thermocouple 400, and the reference electrode 300 and the thermocouple 400 are independently arranged at the notch 101.

[0064] Compared with the prior art, the present invention has at least the following advantages:

[0065] The built-in thermoelectric characterization test model 10 of the sodium-ion battery of the present invention forms a notch 101 on the positive electrode sheet 100, and the thermoelectric characterization measuring body is placed in the notch 101, and the thermoelectric characterization measuring body is insulated from the positive electrode sheet 100 through the insulator 200 and is not in contact. In this way, when the thermoelectric characterization measuring body includes the reference electrode 300, the reference electrode 300 is built into the inside of the core, and the positive electrode sheet 100 corresponding to the reference electrode 300 forms a notch 101, which will not cooperate with the negative electrode sheet to form a sodium-ion migration channel, and thus the situation where the reference electrode 300 hinders the migration of sodium ions and causes sodium deposition on the positive electrode side of the reference electrode 300 will not occur, that is, the problem of inaccurate potential characterization of the reference electrode 300 is effectively avoided, and the accuracy of the potential characterization of the built-in thermoelectric characterization test model 10 of the sodium-ion battery is improved; when the thermoelectric characterization measuring body includes the thermocouple 400, the thermocouple 400 is built into the inside of the core, directly characterizing and measuring the temperature inside the core, effectively avoiding the delay, and improving the accuracy of the temperature characterization of the built-in thermoelectric characterization test model 10 of the sodium-ion battery.

[0066] The following are some specific examples. If % is mentioned, it means by weight percentage. It should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels without special instructions.

[0067] Example 1

[0068] Mix the positive electrode sodium nickel iron manganese oxide, conductive agent, binder, and oxalic acid in a mass percentage of 96.2%: 2%: 1.4%: 0.4%, and after mixing evenly, add NMP step by step and stir to prepare a slurry. The solid content of the slurry is about 70%; coat and dry the prepared slurry on the aluminum foil, and roll the dried electrode sheet.

[0069] Mix the hard carbon negative electrode, conductive agent, binder, and thickener in a mass percentage of 94%: 1.5%: 2.5%: 2%, and add deionized water step by step and stir to prepare a slurry. The solid content of the slurry is about 45%; coat and dry the prepared slurry on the aluminum foil, and roll the dried electrode sheet.

[0070] Soak the enameled wire with a diameter of 100 μm in the paint remover for 5 minutes, and the paint removal distance at both ends is 2 cm.

[0071] The prepared positive and negative electrode sheets are slit and wound. There is a notch formed on the positive electrode sheet, and the width of the notch is greater than the width of the sodium vanadium phosphate reference electrode. When bonding the sodium vanadium phosphate reference electrode with a diameter of 50 nm and a state of charge of 5% SOC to the notch through a polyimide tape, pay attention that there is no contact between the positive electrode sheet and the sodium vanadium phosphate reference electrode. Then, one end of the enameled wire is welded to the surface of the sodium vanadium phosphate reference electrode, and the other end of the enameled wire is led out of the winding core during winding. Finally, it is flattened, the current collector plate is welded, the bottom welding is spot-welded, the groove is rolled, baked, injected with liquid, sealed, formed, and capacity-divided to complete the fabrication of the three-electrode battery.

[0072] Example 2

[0073] The positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid are mixed evenly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%, and then NMP is added step by step for stirring to prepare a slurry, and the solid content of the slurry is about 70%; the prepared slurry is coated and dried on the aluminum foil, and the dried electrode sheet is rolled.

[0074] The hard carbon negative electrode, conductive agent, binder, and thickener are mixed evenly according to the mass percentages of 94%: 1.5%: 2.5%: 2%, and then deionized water is added step by step for stirring to prepare a slurry, and the solid content of the slurry is about 45%; the prepared slurry is coated and dried on the aluminum foil, and the dried electrode sheet is rolled.

[0075] The enameled wire with a diameter of 100 μm is soaked in the paint remover for 5 minutes, and the paint removal distance at both ends is 2 cm.

[0076] The prepared positive and negative electrode sheets are slit and wound. There is a notch formed on the positive electrode sheet, and the width of the notch is greater than the width of the sodium vanadium phosphate reference electrode. When bonding the sodium vanadium phosphate reference electrode with a diameter of 200 nm and a state of charge of 60% SOC to the notch through a polyimide tape, pay attention that there is no contact between the positive electrode sheet and the sodium vanadium phosphate reference electrode. Then, one end of the enameled wire is welded to the surface of the sodium vanadium phosphate reference electrode, and the other end of the enameled wire is led out of the winding core during winding. Finally, it is flattened, the current collector plate is welded, the bottom welding is spot-welded, the groove is rolled, baked, injected with liquid, sealed, formed, and capacity-divided to complete the fabrication of the three-electrode battery.

[0077] Example 3

[0078] The positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid are mixed evenly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%, and then NMP is added step by step for stirring to prepare a slurry, and the solid content of the slurry is about 70%; the prepared slurry is coated and dried on the aluminum foil, and the dried electrode sheet is rolled.

[0079] Mix the hard carbon negative electrode, conductive agent, binder, and thickener evenly according to the mass percentages of 94%: 1.5%: 2.5%: 2%, and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0080] Soak the enameled wire with a diameter of 100 μm in the paint remover for 5 minutes, and the paint removal distance at both ends is 2 cm.

[0081] Cut and wind the prepared positive and negative electrode sheets. There is a notch formed on the positive electrode sheet, and the width of the notch is greater than the width of the sodium vanadium phosphate reference electrode. When bonding the sodium vanadium phosphate reference electrode with a diameter of 300 nm and a charged state of 95% SOC to the notch through a polyimide tape, pay attention that there is no contact between the positive electrode sheet and the sodium vanadium phosphate reference electrode. Then, weld one end of the enameled wire to the surface of the sodium vanadium phosphate reference electrode. When winding, the other end of the enameled wire is led out of the winding core. Finally, perform flattening, welding the current collector plate, spot bottom welding, grooving, baking, injecting electrolyte, sealing, forming, and grading to complete the production of the three-electrode battery.

[0082] Example 4

[0083] Mix the positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid evenly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%, and add NMP step by step for stirring to prepare a slurry with a solid content of about 70%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0084] Mix the hard carbon negative electrode, conductive agent, binder, and thickener evenly according to the mass percentages of 94%: 1.5%: 2.5%: 2%, and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0085] Cut and wind the prepared positive and negative electrode sheets. There is a notch formed on the positive electrode sheet, and the width of the notch is greater than the width of the probe of the T-shaped ultra-fine temperature measuring wire. When bonding the T-shaped ultra-fine temperature measuring wire with a heat-conducting adhesive (thickness of 5 μm, mass ratio of zirconia: polydimethylsiloxane = 2:8) coated on the probe surface to the notch through a polyimide tape, pay attention that there is no contact between the positive electrode sheet and the sodium vanadium phosphate reference electrode. When winding, the end of the T-shaped ultra-fine temperature measuring wire far from the probe is led out of the winding core. Finally, perform flattening, welding the current collector plate, spot bottom welding, grooving, baking, injecting electrolyte, sealing, forming, grading, and complete the production of the built-in thermocouple battery.

[0086] Example 5

[0087] Mix sodium nickel iron manganese oxide for the positive electrode, conductive agent, binder, and oxalic acid in a mass percentage of 96.2%: 2%: 1.4%: 0.4%. After mixing evenly, add NMP step by step and stir to prepare a slurry with a solid content of about 70%. Coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0088] Mix hard carbon negative electrode, conductive agent, binder, and thickener in a mass percentage of 94%: 1.5%: 2.5%: 2%. Mix evenly and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%. Coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0089] Cut and wind the prepared positive and negative electrode sheets. There is a notch formed on the positive electrode sheet, and the width of the notch is greater than the width of the probe of the T-shaped ultra-fine temperature measurement wire. When bonding the T-shaped ultra-fine temperature measurement wire with a heat-conducting adhesive (thickness of 50 μm, mass ratio of zirconia: polydimethylsiloxane = 2:8) coated on the probe surface to the notch with polyimide tape, pay attention that the positive electrode sheet has no contact with the sodium vanadium phosphate reference electrode. During winding, the end of the T-shaped ultra-fine temperature measurement wire far from the probe is led out of the winding core. Finally, perform flattening, welding the current collector plate, spot bottom welding, grooving, baking, injecting electrolyte, sealing, forming, grading, and complete the production of the built-in thermocouple battery.

[0090] Example 6

[0091] Mix sodium nickel iron manganese oxide for the positive electrode, conductive agent, binder, and oxalic acid in a mass percentage of 96.2%: 2%: 1.4%: 0.4%. After mixing evenly, add NMP step by step and stir to prepare a slurry with a solid content of about 70%. Coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0092] Mix hard carbon negative electrode, conductive agent, binder, and thickener in a mass percentage of 94%: 1.5%: 2.5%: 2%. Mix evenly and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%. Coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0093] Cut and wind the prepared positive and negative electrode sheets. There is a notch formed on the positive electrode sheet, and the width of the notch is greater than the width of the probe of the T-shaped ultra-fine temperature measurement wire. When bonding the T-shaped ultra-fine temperature measurement wire with a heat-conducting adhesive (thickness of 100 μm, mass ratio of zirconia: polydimethylsiloxane = 3:7) coated on the probe surface to the notch with polyimide tape, pay attention that the positive electrode sheet has no contact with the sodium vanadium phosphate reference electrode. During winding, the end of the T-shaped ultra-fine temperature measurement wire far from the probe is led out of the winding core. Finally, perform flattening, welding the current collector plate, spot bottom welding, grooving, baking, injecting electrolyte, sealing, forming, grading, and complete the production of the built-in thermocouple battery.

[0094] Example 7

[0095] The positive electrode sodium nickel iron manganeseate, conductive agent, binder, and oxalic acid were mixed uniformly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%. After that, NMP was added step by step for stirring to prepare a slurry, and the solid content of the slurry was about 70%. The prepared slurry was coated and dried on aluminum foil, and the dried electrode sheet was rolled.

[0096] The hard carbon negative electrode, conductive agent, binder, and thickening agent were mixed uniformly according to the mass percentages of 94%: 1.5%: 2.5%: 2%. Then, deionized water was added step by step for stirring to prepare a slurry, and the solid content of the slurry was about 45%. The prepared slurry was coated and dried on aluminum foil, and the dried electrode sheet was rolled.

[0097] The prepared positive and negative electrode sheets were cut and wound. There was a notch formed on the positive electrode sheet, and the width of the notch was greater than the width of the probe of the T-type ultra-fine temperature measurement wire. When the T-type ultra-fine temperature measurement wire with its probe surface coated with paraffin oil (melting temperature of 100 °C and thickness of 100 μm) was bonded to the notch with polyimide tape, it should be noted that the positive electrode sheet had no contact with the sodium vanadium phosphate reference electrode. During winding, the end of the T-type ultra-fine temperature measurement wire far from the probe was led out of the winding core. Finally, it was flattened, the current collector plate was welded, the bottom welding was spot-welded, the groove was rolled, baked, the electrolyte was injected, sealed, formed, capacity-fractionated, and the production of the built-in thermocouple battery was completed.

[0098] Example 8

[0099] The positive electrode sodium nickel iron manganeseate, conductive agent, binder, and oxalic acid were mixed uniformly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%. After that, NMP was added step by step for stirring to prepare a slurry, and the solid content of the slurry was about 70%. The prepared slurry was coated and dried on aluminum foil, and the dried electrode sheet was rolled.

[0100] The hard carbon negative electrode, conductive agent, binder, and thickening agent were mixed uniformly according to the mass percentages of 94%: 1.5%: 2.5%: 2%. Then, deionized water was added step by step for stirring to prepare a slurry, and the solid content of the slurry was about 45%. The prepared slurry was coated and dried on aluminum foil, and the dried electrode sheet was rolled.

[0101] The prepared positive and negative electrode sheets are slit and wound. Notches are formed at the 1 / 4, 1 / 2, and 3 / 4 positions in the length direction of the positive electrode sheet respectively. The width of each notch is greater than the width of the probe of the T-shaped ultra-fine temperature measuring wire. When the T-shaped ultra-fine temperature measuring wire with a heat-conducting adhesive (thickness: 100 μm, mass ratio of zirconia: polydimethylsiloxane = 2:8) coated on its surface is bonded to the notch through a polyimide tape, attention should be paid that there is no contact between the positive electrode sheet and the sodium vanadium phosphate reference electrode. During winding, the end of the T-shaped ultra-fine temperature measuring wire far from the probe is led out of the winding core. Finally, it is flattened, the current collector plate is welded, the bottom spot welding is carried out, the grooving is done, baking, liquid injection, sealing, formation, grading are carried out, and the production of the built-in thermocouple battery is completed.

[0102] Example 9

[0103] The positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid are mixed uniformly according to the mass percentage of 96.2%: 2%: 1.4%: 0.4%, and then NMP is added step by step for stirring to prepare a slurry. The solid content of the slurry is about 70%. The prepared slurry is coated and dried on the aluminum foil, and the dried electrode sheet is rolled.

[0104] The hard carbon negative electrode, conductive agent, binder, and thickening agent are mixed uniformly according to the mass percentage of 94%: 1.5%: 2.5%: 2%, and then deionized water is added step by step for stirring to prepare a slurry. The solid content of the slurry is about 45%. The prepared slurry is coated and dried on the aluminum foil, and the dried electrode sheet is rolled.

[0105] The prepared positive and negative electrode sheets are slit and wound. Notches are formed at the 1 / 4, 1 / 2, and 3 / 4 positions in the width direction of the positive electrode sheet respectively. The width of each notch is greater than the width of the probe of the T-shaped ultra-fine temperature measuring wire. When the T-shaped ultra-fine temperature measuring wire with a heat-conducting adhesive (thickness: 100 μm, mass ratio of zirconia: polydimethylsiloxane = 2:8) coated on its surface is bonded to the notch through a polyimide tape, attention should be paid that there is no contact between the positive electrode sheet and the sodium vanadium phosphate reference electrode. During winding, the end of the T-shaped ultra-fine temperature measuring wire far from the probe is led out of the winding core. Finally, it is flattened, the current collector plate is welded, the bottom spot welding is carried out, the grooving is done, baking, liquid injection, sealing, formation, grading are carried out, and the production of the built-in thermocouple battery is completed.

[0106] Comparative Example 1

[0107] The positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid are mixed uniformly according to the mass percentage of 96.2%: 2%: 1.4%: 0.4%, and then NMP is added step by step for stirring to prepare a slurry. The solid content of the slurry is about 70%. The prepared slurry is coated and dried on the aluminum foil, and the dried electrode sheet is rolled.

[0108] Mix the hard carbon negative electrode, conductive agent, binder, and thickener evenly according to the mass percentages of 94%: 1.5%: 2.5%: 2%, and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0109] Soak the enameled wire with a diameter of 100 μm in the paint remover for 5 minutes, and the paint removal distance at both ends is 2 cm.

[0110] Cut and wind the prepared positive and negative electrode sheets. When winding, add copper wire and cover a layer of separator, and finally carry out flattening, welding the current collector plate, spot bottom welding, rolling grooves, baking, injecting electrolyte, sealing, forming, grading, and lithium plating to complete the production of the three-electrode battery.

[0111] Comparative Example 2

[0112] Mix the positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid evenly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%, and add NMP step by step for stirring to prepare a slurry with a solid content of about 70%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0113] Mix the hard carbon negative electrode, conductive agent, binder, and thickener evenly according to the mass percentages of 94%: 1.5%: 2.5%: 2%, and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0114] Cut and wind the prepared positive and negative electrode sheets. When winding, bond the T-type ultra-fine temperature measurement wire on the outside of the winding core through a polyimide tape, and finally carry out flattening, welding the current collector plate, spot bottom welding, rolling grooves, baking, injecting electrolyte, sealing, forming, grading, and complete the production of the built-in thermocouple battery.

[0115] Comparative Example 3

[0116] Mix the positive nickel iron manganese sodium, conductive agent, binder, and oxalic acid evenly according to the mass percentages of 96.2%: 2%: 1.4%: 0.4%, and add NMP step by step for stirring to prepare a slurry with a solid content of about 70%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0117] Mix the hard carbon negative electrode, conductive agent, binder, and thickener evenly according to the mass percentages of 94%: 1.5%: 2.5%: 2%, and add deionized water step by step for stirring to prepare a slurry with a solid content of about 45%; coat and dry the prepared slurry on aluminum foil, and roll the dried electrode sheet.

[0118] The prepared positive and negative electrode sheets are slit and wound, and finally flattened, the current collector plate is welded, the bottom spot welding is carried out, the grooving is carried out, baking, liquid injection, sealing, formation, and grading are carried out.

[0119] A T-shaped ultra-fine temperature measurement wire is added outside the battery and fixed with polyimide tape to complete the production of the built-in thermocouple battery.

[0120] It can be understood that the above examples and comparative examples all use cylindrical batteries for experiments. The positive electrode uses sodium nickel iron manganate, and the negative electrode uses hard carbon. It can also be understood that the preparation of the three-electrode battery in Comparative Example 1 is actually the preparation of a conventional built-in three-electrode battery. The operations such as winding, baking, and liquid injection in Examples 1 to 3 of the present application that are not described in detail are the same as those of it; the preparation of the battery containing a thermocouple in Comparative Example 2 is actually the preparation of a conventional built-in thermocouple battery. The operations such as winding, baking, and liquid injection in Examples 4 to 8 of the present application that are not described in detail are the same as those of it; the preparation of the battery containing a thermocouple in Comparative Example 3 is actually the preparation of a conventional external thermocouple battery. The operations such as winding, baking, and liquid injection that are not described in detail in it are the same as those of Comparative Example 2.

[0121] The following conducts three-electrode experiments on the cylindrical batteries obtained in Example 3 and Comparative Example 1. Specifically, as Figure 1 shown, it is a schematic structural diagram of the positive electrode sheet of Comparative Example 1; Figure 2 It is a schematic structural diagram of the positive electrode sheet of Example 3; The test results are evaluated by the stable duration of the three-electrode voltage. When the voltage between the reference electrode and the negative electrode fluctuates frequently, or the voltage difference > 5 mV within 1 day, it is regarded as the failure of the three electrodes. The evaluation results of Example 3 and Comparative Example 1 are shown in Table 1.

[0122] Table 1

[0123]

[0124] It can be seen from Table 1 that the present invention has achieved a huge improvement in the three-electrode stability. It has very strong practical value in exploring the failure modes and failure mechanisms during the long-term performance test of sodium-ion batteries.

[0125] The following conducts thermocouple experiments on Examples 6, 8-9 and Comparative Examples 2-3. Specifically, Comparative Example 2 is a common scheme, and Comparative Example 3 is a control example. As Figure 3 shown, it is a schematic structural diagram of the positive electrode sheet of Example 6; Based on the battery safety test, the experimental results are evaluated in terms of the stability of the thermocouple, the temperature start response time, and the highest temperature measured during out-of-control. The experimental results are shown in Table 2.

[0126]

[0127]

[0128] As can be seen from Table 2, during the safety test, there are significant differences in the temperature change and conduction direction for different tests between the inside and outside of the battery cell, between the inner and outer sides of the wound core, and in the height direction of the battery cell. For Examples 6, 8 - 9, there is a very high improvement in accuracy in characterizing the thermal runaway temperature of the sodium - ion battery, providing effective data support for studying the thermal runaway mode and mechanism.

[0129] The above - mentioned embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A sodium ion battery built-in thermoelectric characterization test model, characterized in that: The device comprises a positive electrode sheet, an insulator and a thermoelectric characterization measuring body, wherein the positive electrode sheet is provided with at least one notch, the thermoelectric characterization measuring body is accommodated in the notch, and the thermoelectric characterization measuring body is connected to the positive electrode sheet through the insulator, and the thermoelectric characterization measuring body is spaced apart from the positive electrode sheet; The thermoelectric characterization measuring body is at least one of a sodium vanadium phosphate reference electrode and a thermocouple, and the sodium vanadium phosphate reference electrode and the thermocouple are independently arranged at the notch.

2. The sodium ion battery built-in thermoelectric characterization test model according to claim 1, characterized in that: The number of the notch is one, and the thermoelectric characterization measuring body is a reference electrode; or, The number of the notch is one, and the thermoelectric characterization measuring body is a thermocouple; or, The number of the notches is one, the thermoelectric characterization measuring body comprises a reference electrode and a thermocouple, the reference electrode and the thermocouple are accommodated at the notch with a gap, and the reference electrode and the thermocouple are connected to the positive electrode sheet through the insulator; or, The number of the notches is two, and the two notches are arranged at intervals on the positive electrode sheet. The thermoelectric characterization measuring body includes a reference electrode and a thermocouple. The reference electrode is accommodated in one of the notches, and the reference electrode is connected to the positive electrode sheet through the insulator. The thermocouple is accommodated in the other notch, and the thermocouple is connected to the positive electrode sheet through the insulator; or, There are multiple notches, and the multiple notches are arranged at intervals on the positive electrode sheet. The thermoelectric characterization measuring body includes a reference electrode and a thermocouple. The reference electrode is accommodated in at least one of the notches, and the reference electrode is connected to the positive electrode sheet through the insulator. The thermocouple is accommodated in at least another notch, and the thermocouple is connected to the positive electrode sheet through the insulator; or, The number of the notches is two or more, and the two or more notches are arranged at intervals on the positive electrode sheet. The thermoelectric characterization measuring body is a reference electrode, and a reference electrode is arranged at each notch, and the reference electrode at each notch is connected to the positive electrode sheet through the insulator; or, The number of the notches is two or more, and the two or more notches are arranged at intervals on the positive electrode sheet. The thermoelectric characterization measuring body is a thermocouple, and a thermocouple is arranged at each notch. The thermocouple at each notch is connected to the positive electrode sheet through the insulator.

3. The sodium ion battery built-in thermoelectric characterization test model according to claim 1, characterized in that: The reference electrode is a sodium vanadium phosphate reference electrode.

4. The sodium ion battery built-in thermoelectric characterization test model according to claim 3, characterized in that: The state of charge of the sodium vanadium phosphate reference electrode is 5% SOC to 95% SOC; and / or, The diameter of the sodium vanadium phosphate reference electrode is 50nm to 300nm.

5. The sodium ion battery built-in thermoelectric characterization test model according to claim 1, characterized in that: The thermocouple is a K-type ultra-fine temperature measuring wire or a T-type ultra-fine temperature measuring wire.

6. The sodium ion battery built-in thermoelectric characterization test model according to claim 5, characterized in that: The diameter of the thermocouple is 50 μm to 300 μm.

7. The sodium ion battery built-in thermoelectric characterization test model according to claim 1, characterized in that: A coating layer is attached to the surface of the thermocouple, and the coating layer is a heat-conducting adhesive layer or a paraffin oil layer.

8. The sodium ion battery built-in thermoelectric characterization test model according to claim 7, characterized in that: The coating layer has a thickness of 5 μm to 100 μm; and / or, The thermally conductive adhesive layer includes a thermally conductive filler and an adhesive material; and / or the paraffin oil is selected from paraffin oils with different melting temperatures.

9. A method for preparing a sodium ion battery built-in thermoelectric characterization test model, characterized in that: The method for preparing the sodium ion battery built-in thermoelectric characterization test model according to any one of claims 1 to 8 comprises the following steps: Get the positive electrode; Cutting the positive electrode sheet so that at least one notch is formed on the positive electrode sheet; The notch is assembled with an insulator so that a thermoelectric characterization measuring body is accommodated on the notch through the insulator, and the thermoelectric characterization measuring body is spaced apart from the positive electrode sheet, wherein the thermoelectric characterization measuring body is at least one of a reference electrode and a thermocouple, and the reference electrode and the thermocouple are independently arranged at the notch.

10. An application of thermoelectric characterization test using the test model, characterized in that: The sodium ion battery built-in thermoelectric characterization test model described in any one of claims 1 to 8 is applied to the potential measurement of the built-in electrochemical three electrodes of the sodium ion battery and the temperature measurement of the built-in thermocouple of the sodium ion battery.

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