A lithium ion three-electrode battery and a preparation method thereof

Abstract

The application provides a lithium ion three-electrode battery and a preparation method thereof, a composite electrode sheet, a first surface of the composite electrode sheet is a positive electrode material layer, and a second surface of the composite electrode sheet is a negative electrode material layer; a reference electrode sheet is arranged on the first surface and the second surface of the composite electrode sheet, and the reference electrode sheet is separated from the composite electrode sheet through a diaphragm. The reference electrode is arranged on the positive electrode and the negative electrode of the battery respectively, so that the influence of the reference electrode sheet on the electric field distribution between the positive electrode and the negative electrode is avoided, a reference electrode sheet with a large area can be used, and the accuracy of potential testing is improved.

Description

Technical Field

[0001] This invention relates to the field of new energy power lithium battery technology, and in particular to a lithium-ion three-electrode battery and its preparation method. Background Technology

[0002] In recent years, the use of three-electrode batteries to study the potential changes, impedance changes, and lithium plating behavior of lithium-ion batteries under different conditions has become an important analytical method. To date, many methods for preparing three electrodes have been proposed, including the selection of the reference electrode type, such as copper wire or lithium-copper composite strip; and the selection of the reference electrode position, such as placing the reference electrode between the positive and negative electrodes or at the edges of the positive and negative electrodes. Among these factors, the type and position of the reference electrode, as well as the fabrication process, all affect the test results for potential, impedance, and other parameters.

[0003] Currently, commonly used three-electrode batteries typically insert a reference electrode between or at the edges of the positive and negative electrodes to measure the potential changes during dynamic charging and discharging. Placing the reference electrode at the edge of the cell causes a potential deviation due to the higher impedance between the reference electrode and the electrodes. Placing the reference electrode between the electrodes affects the electric field distribution between them, and the smaller size of the reference electrode results in a smaller measurement area, impacting the accuracy of the potential test. Therefore, selecting a three-electrode battery that minimizes the impact on the positive and negative electrodes while accurately measuring their potentials is extremely important. Summary of the Invention

[0004] Based on the problems of existing technologies, this invention provides a lithium-ion three-electrode battery and its preparation method, aiming to solve technical problems such as inaccurate potential testing of existing three-electrode batteries.

[0005] A lithium-ion three-electrode battery, comprising:

[0006] The composite electrode has a positive electrode material layer on its first surface and a negative electrode material layer on its second surface.

[0007] Reference electrode sheets are disposed on both the first and second surfaces facing the composite electrode sheet, and the reference electrode sheets are separated from the composite electrode sheet by a diaphragm.

[0008] Furthermore, the reference electrode sheet includes a reference electrode current collector and a reference electrode material region, the reference electrode material region being disposed on the first surface of the reference electrode current collector, the first surface of the reference electrode current collector facing the composite electrode sheet.

[0009] Furthermore, a reference electrode tab is provided on the second surface of the reference electrode current collector.

[0010] Furthermore, the composite electrode includes an intermediate insulating layer;

[0011] The first surface of the intermediate insulating layer is provided with an aluminum plating layer and a first blank area is left. The first surface of the aluminum plating layer is provided with a positive electrode material layer.

[0012] The second surface of the intermediate insulating layer is provided with a copper plating layer and a second blank area is left. The negative electrode material layer is provided on the second surface of the copper plating layer.

[0013] The first and second blank areas are opposite each other.

[0014] Furthermore, the first surface of the aluminum coating has a third blank area, and the positive electrode tab is connected to the third blank area;

[0015] The second surface of the copper plating layer has a fourth blank area, and the negative electrode tab is connected to the fourth blank area.

[0016] The third blank area is positioned vertically opposite the second blank area;

[0017] The fourth blank area is set vertically opposite to the first blank area.

[0018] A method for preparing a lithium-ion three-electrode battery, characterized in that the preparation of the aforementioned lithium-ion three-electrode battery includes the following steps:

[0019] Step A1: Prepare composite electrode sheet, reference electrode sheet, and separator, wherein the first surface of composite electrode sheet is a positive electrode material layer and the second surface of composite electrode sheet is a negative electrode material layer.

[0020] Step A2 involves assembling the reference electrode, separator, composite electrode, separator, and reference electrode in that order to obtain a lithium-ion three-electrode battery.

[0021] Furthermore, in step A1, the prepared reference electrode sheet includes a reference electrode current collector and a reference electrode material region, wherein the reference electrode material region is disposed on the first surface of the reference electrode current collector;

[0022] In step A2, during assembly, the first surface of the reference electrode current collector faces the composite electrode.

[0023] Furthermore, step A1 also includes setting a reference electrode tab on the second surface of the reference electrode sheet.

[0024] Furthermore, in step A1, the prepared composite electrode includes an intermediate insulating layer;

[0025] The first surface of the intermediate insulating layer is plated with an aluminum plating layer, and a first blank area is left. The positive electrode material layer is disposed on the first surface of the aluminum plating layer.

[0026] The second surface of the intermediate insulating layer is plated with a copper plating layer, and a second blank area is left. The negative electrode material layer is disposed on the second surface of the copper plating layer.

[0027] The first and second blank areas are opposite each other.

[0028] Furthermore, in the composite electrode prepared in step A1;

[0029] A third blank area is left on the first surface of the aluminum coating;

[0030] A fourth blank area is left on the second surface of the copper plating.

[0031] The third blank area is positioned vertically opposite the second blank area;

[0032] The fourth blank area is positioned vertically opposite the first blank area.

[0033] Step A1 also includes connecting a positive electrode tab to the third blank area of ​​the aluminum plating layer of the composite electrode, and connecting a negative electrode tab to the fourth blank area of ​​the copper plating layer of the composite electrode.

[0034] The beneficial technical effects of this invention are as follows: reference electrode sheets are set for the positive and negative electrodes respectively, which avoids affecting the electric field distribution between the positive and negative electrodes when the reference electrode is placed between them. At the same time, the area of ​​the reference electrode is increased, which improves the accuracy of potential testing. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a lithium-ion three-electrode battery according to the present invention;

[0036] Figure 2-4 This is a schematic diagram of the intermediate insulating layer, aluminum plating layer, and copper plating layer of a lithium-ion three-electrode battery according to the present invention;

[0037] Figure 5 This is a flowchart illustrating the steps of a method for preparing a lithium-ion three-electrode battery according to the present invention.

[0038] Figure 6 This is a comparison diagram of the potential test results of a specific embodiment and a comparative example of the preparation method of a lithium-ion three-electrode battery of the present invention.

[0039] in,

[0040] 1-Aluminum-plastic film;

[0041] 2-Reference electrode current collector;

[0042] 3-Reference electrode material area;

[0043] 4-Septum;

[0044] 5- Positive electrode material layer;

[0045] 6-Aluminum coating;

[0046] 7-Intermediate insulating layer;

[0047] 8- Copper plating;

[0048] 9-Negative electrode material layer;

[0049] 10-Reference electrode tab;

[0050] 11-Positive electrode tab;

[0051] 12-Negative electrode tab;

[0052] 13-Through hole. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0055] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0056] See Figure 1 This invention provides a lithium-ion three-electrode battery, comprising:

[0057] The composite electrode has a first surface as a positive electrode material layer (5) and a second surface as a negative electrode material layer (9).

[0058] Reference electrode sheets are provided on both the first and second surfaces facing the composite electrode sheet, and the reference electrode sheets are separated from the composite electrode sheet by a diaphragm (4).

[0059] Unlike existing technologies that place the reference electrode between the positive and negative electrodes, this invention places reference electrodes on both sides of the positive and negative electrodes, reducing the impact on the electric field distribution between the positive and negative electrodes. Furthermore, placing the reference electrode on both sides of the positive and negative electrodes allows for a larger size compared to placing it between the positive and negative electrodes, resulting in a wider measurement range and more accurate potential testing.

[0060] The present invention provides reference electrode sheets for the positive and negative electrodes respectively, which are separated by a diaphragm (4). This avoids the impact of the electric field distribution between the positive and negative electrodes when the reference electrode sheets are placed between them. At the same time, the area of ​​the reference electrode is increased, which improves the accuracy of the potential test.

[0061] Specifically, the first and second surfaces mentioned in this article are opposite surfaces, such as one being the front and the other the back, or one being the top surface and the other the bottom surface.

[0062] Furthermore, the reference electrode sheet includes a reference electrode current collector (2) and a reference electrode material area (3), the reference electrode material area (3) is disposed on the first surface of the reference electrode current collector (2), and the first surface of the reference electrode current collector (2) faces the composite electrode sheet.

[0063] Furthermore, a reference electrode tab (10) is provided on the second surface of the reference electrode current collector (2).

[0064] Specifically, the reference electrode tab (10) is disposed on the second surface of the reference electrode current collector (2) by welding.

[0065] See Figure 1-4 Furthermore, the composite electrode includes an intermediate insulating layer (7);

[0066] An aluminum plating layer (6) is provided on the first surface of the intermediate insulating layer, and a first blank area is left. A positive electrode material layer (5) is provided on the first surface of the aluminum plating layer (6); the second surface of the aluminum plating layer (6) is in contact with the first surface of the intermediate insulating layer.

[0067] The second surface of the intermediate insulating layer is provided with a copper plating layer (8) and a second blank area is left. The second surface of the copper plating layer (8) is provided with a negative electrode material layer (9). The first surface of the copper plating layer (8) is in contact with the second surface of the intermediate insulating layer.

[0068] The first and second blank areas are opposite each other.

[0069] Specifically, for the first surface of the intermediate insulating layer (7), the area where no aluminum plating is formed is a blank area, and for the second surface of the intermediate insulating layer (7), the area where no copper plating is formed is a blank area. The first blank area is a part of the blank area on the first surface of the intermediate insulating layer (7), and the second blank area is a part of the blank area on the second surface of the intermediate insulating layer (7). The first blank area and the second blank area are opposite each other.

[0070] In this invention, left and right are... Figure 1 The middle insulating layer (7) is used as a reference, with the left half of the middle insulating layer (7) being left and the right half of the middle insulating layer (7) being right.

[0071] The first blank area and the second blank area are opposite each other. For example, in one embodiment, the first blank area is the left side of the first surface of the intermediate insulating layer (7), and the second blank area is the right side of the second surface of the intermediate insulating layer (7). In another embodiment, the first blank area is the right side of the first surface of the intermediate insulating layer (7), and the second blank area is the left side of the second surface of the intermediate insulating layer (7).

[0072] Furthermore, the first surface of the aluminum coating (6) has a third blank area, and the third blank area is connected to the positive electrode tab (11);

[0073] The second surface of the copper plating layer (8) has a fourth blank area, and the fourth blank area is connected to the negative electrode tab (12);

[0074] The third blank area is positioned vertically opposite the second blank area;

[0075] The fourth blank area is set vertically opposite to the first blank area.

[0076] For the first surface of the aluminum coating (6), the area where the positive electrode material layer (5) is not formed is a blank area. The third blank area is a part of the blank area on the first surface of the aluminum coating (6).

[0077] For the second surface of the copper plating layer (8), the area where the negative electrode material layer (9) is not formed is a blank area. The fourth blank area is a part of the blank area on the second surface of the copper plating layer (8).

[0078] Specifically, the width of the third blank area is greater than the width of the second blank area, and the width of the fourth blank area is greater than the width of the first blank area. Specifically, the third blank area of ​​the aluminum coating (6) is connected to the positive electrode tab (11) by welding.

[0079] Specifically, the fourth blank area of ​​the copper plating layer (8) is connected to the negative electrode tab (12) by welding.

[0080] Specifically, the reference electrode, composite electrode and diaphragm (4) are encapsulated in an aluminum-plastic film (1);

[0081] Specifically, the aluminum-plastic film (1) is filled with electrolyte.

[0082] Furthermore, the intermediate insulating layer (7) is formed of one or more of the following materials: polycarbonate PC, polyethylene PE, polypropylene PP, polyethylene terephthalate PET, polymethyl methacrylate PMMA, and polystyrene PS.

[0083] Preferably, the thickness of the intermediate insulating layer (7) is 6-20 μm.

[0084] Preferably, the thickness of the aluminum coating (6) is 1-5 μm.

[0085] Preferably, the thickness of the copper plating layer (8) is 1-5 μm.

[0086] The aluminum plating (6) and copper plating (8) can be formed on the corresponding surfaces of the intermediate insulating layer (7) by one or more methods such as vapor deposition, spraying, and electroplating.

[0087] Preferably, the size of the positive electrode material layer (5) is 50-150 mm. For a rectangular positive electrode material layer (5), the size refers to the length and width of the positive electrode material layer (5), that is, the preferred range of length and width is 50-150 mm.

[0088] Preferably, the size of the negative electrode material layer (9) is 50-150 mm. For a rectangular negative electrode material layer (9), the size refers to the length and width of the negative electrode material layer (9), that is, the length and width are preferably in the range of 50-150 mm.

[0089] The aluminum plating (6) and the copper plating (8) exist at different positions when the tabs are welded, that is, the positive tab (11) is only connected to the aluminum plating (6), and the negative tab (12) is only connected to the copper plating (8). Both the positive tab (11) and the negative tab (12) are tabs.

[0090] Specifically, the positive electrode tab (11) is an aluminum tab sheet.

[0091] Specifically, the negative electrode tab (12) is a copper-plated nickel tab sheet.

[0092] Specifically, the diaphragm (4) is made of polyethylene (PE).

[0093] The positive electrode material layer (5) is a positive electrode active material layer coated on the aluminum plating layer (6).

[0094] The negative electrode material layer (9) is a layer of negative electrode active material coated on the copper plating layer (8).

[0095] Furthermore, the area of ​​the negative electrode material layer (9) is larger than the area of ​​the positive electrode material layer (5).

[0096] Preferably, the negative electrode material layer (9) includes an overhang region and a non-overhang region. The overhang region refers to the non-overlapping region of the negative electrode material layer (9) relative to the positive electrode material layer (5), and the non-overhang region refers to the overlapping region relative to the positive electrode material layer (5). Preferably, the width of the overhang region is 1-10 mm. The width of the overhang region refers to the distance between the boundary between the overhang region and the non-overhang region and the boundary of the negative electrode material layer (9).

[0097] Preferably, the width of the third blank area on the aluminum coating (6) for welding the positive electrode tab (11) is 5-25 mm.

[0098] Furthermore, the width of the fourth blank area on the copper plating layer (8) for welding the negative electrode tab (12) is 5-25 mm.

[0099] Furthermore, the composite electrode has several through holes that pass through the positive electrode material layer (5), the aluminum plating layer (6), the intermediate insulating layer (7), the copper plating layer (8), and the negative electrode material layer (9) in sequence.

[0100] The composite electrode has a perforated structure to facilitate the transport of lithium ions.

[0101] Furthermore, the through-hole can be circular, square, or oval in shape.

[0102] Preferably, the diameter of the through hole is 1-500 μm.

[0103] Preferably, the porosity of the through holes is 50-80%.

[0104] Furthermore, the through holes are evenly distributed.

[0105] The composite electrode is perforated by laser or mechanical means to form a dense through-hole structure on the electrode. The through holes are evenly distributed and the shape of the through holes is preferably, but not limited to, circular, square, or elliptical. The diameter of the holes is preferably 1um-500um and the porosity of the through holes in the composite electrode is preferably 50-80%.

[0106] Furthermore, the reference electrode sheet is a lithium-copper composite strip.

[0107] Furthermore, the reference electrode material region (3) is selected from lithium metal or lithium oxide with a voltage platform, such as lithium iron phosphate or lithium cobalt oxide.

[0108] See Figure 5 The present invention also provides a method for preparing a lithium-ion three-electrode battery, which is used to prepare a lithium-ion three-electrode battery as described above, comprising the following steps:

[0109] Step A1: Prepare composite electrode sheet, reference electrode sheet, and separator, wherein the first surface of composite electrode sheet is a positive electrode material layer and the second surface of composite electrode sheet is a negative electrode material layer.

[0110] Step A2 involves assembling the reference electrode, separator, composite electrode, separator, and reference electrode in that order to obtain a lithium-ion three-electrode battery.

[0111] Furthermore, in step A1, the prepared reference electrode sheet includes a reference electrode current collector and a reference electrode material region, wherein the reference electrode material region is disposed on the first surface of the reference electrode current collector;

[0112] In step A2, during assembly, the first surface of the reference electrode current collector faces the composite electrode.

[0113] Furthermore, in step A1, the prepared composite electrode includes an intermediate insulating layer;

[0114] The first surface of the intermediate insulating layer is plated with an aluminum plating layer, and a first blank area is left. The positive electrode material layer is disposed on the first surface of the aluminum plating layer.

[0115] The second surface of the intermediate insulating layer is plated with a copper plating layer, and a second blank area is left. The negative electrode material layer is disposed on the second surface of the copper plating layer.

[0116] The first and second blank areas are opposite each other.

[0117] Furthermore, in the composite electrode prepared in step A1;

[0118] A third blank area is left on the first surface of the aluminum coating;

[0119] A fourth blank area is left on the second surface of the copper plating.

[0120] The third blank area is positioned vertically opposite the second blank area;

[0121] The fourth blank area is positioned vertically opposite the first blank area.

[0122] Step A1 further includes connecting a positive electrode tab to the third blank area of ​​the aluminum plating layer of the composite electrode, and connecting a negative electrode tab to the fourth blank area of ​​the copper plating layer of the composite electrode. Specifically, in step A1, when preparing the composite electrode, an intermediate insulating layer is first prepared, an aluminum plating layer is formed on the first surface of the intermediate insulating layer, and a copper plating layer is formed on the second surface. Then, a positive electrode material layer is formed on the first surface of the aluminum plating layer, and a negative electrode material layer is formed on the second surface of the copper plating layer, thereby forming the composite electrode. Subsequently, a positive electrode tab is connected to the first surface of the aluminum plating layer, and a negative electrode tab is connected to the second surface of the copper plating layer.

[0123] Specifically, in step A1, when preparing the reference electrode sheet, a composite layer of the reference electrode current collector and the reference electrode material area is first formed to form the reference electrode sheet, and then the reference electrode tab is fabricated on the reference electrode current collector.

[0124] Specifically, in step A2, the reference electrode sheet, diaphragm, composite electrode sheet, diaphragm, and reference electrode sheet are assembled in that order, and after the electrolyte is injected, they are encapsulated with an aluminum-plastic film.

[0125] Furthermore, in step A1, the intermediate insulating layer is formed using one or more of the following materials: polycarbonate, polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, and polystyrene.

[0126] Furthermore, in step A1, the thickness of the intermediate insulating layer is 6-20 μm.

[0127] Furthermore, the preparation of the composite electrode in step A1 also includes opening several through holes on the composite electrode, with the through holes sequentially penetrating the positive electrode material layer, the aluminum plating layer, the intermediate insulating layer, the copper plating layer, and the negative electrode material layer.

[0128] Furthermore, the through-hole can be circular, square, or oval in shape.

[0129] Example

[0130] In this embodiment, the method of the present invention is mainly used to prepare a lithium-ion three-electrode battery, and the prepared lithium-ion three-electrode battery includes:

[0131] Composite electrode;

[0132] The reference electrode is a lithium-copper composite strip;

[0133] The diaphragm is made of PE (polyethylene) with a thickness of 14µm.

[0134] The thickness of the aluminum-plastic film is 148µm;

[0135] The positive electrode tab is made of aluminum.

[0136] The negative electrode tab is made of copper-plated nickel tab.

[0137] The electrolyte composition includes: 1M LiPF6 (1 mole of lithium hexafluorophosphate), 1:1 EC / DMC (solvents are ethylene carbonate and dimethyl carbonate in a 1:1 ratio), and 10% FEC (additive is 10% fluoroethylene carbonate).

[0138] The specific preparation process is as follows.

[0139] Step A1: Prepare composite electrode sheets, reference electrode sheets, and diaphragm.

[0140] The process of preparing composite electrodes includes:

[0141] (1) Prepare an intermediate insulating layer with a size of 100×100mm; form an aluminum plating layer on the first surface of the intermediate insulating layer and a copper plating layer on the second surface, with the aluminum plating layer having a size of 100×90mm and the copper plating layer having a size of 100×90mm.

[0142] (2) Forming positive and negative electrodes: For the positive electrode fabrication, NCM811 (nickel-cobalt-manganese content ratio of 8:1:1), SP (conductive carbon black), and PVDF (polyvinylidene fluoride) are mixed in a ratio of 95:2.5:2.5. After mixing, the slurry is coated onto the first surface of the aluminum coating, with a coating capacity of 9 mAh / cm². 2 The coated area has a size of 60×60mm and a compaction density of 3.5g / cm³. 3 This forms the positive electrode material layer, serving as the positive electrode. For the negative electrode fabrication, SiO / C (silicon oxide / carbon), SP (conductive carbon black), and CMC (sodium carboxymethyl cellulose) are mixed in a ratio of 90:5:5 to form a slurry. After mixing, the slurry is coated onto the second surface of the copper plating layer, with a coating capacity of 10.8 mAh / cm². 2 The NP ratio (excess negative electrode ratio) is 1.2, and the compaction density is 1.6 g / cm³. 3 The coated area is 65×65mm in size, forming a negative electrode material layer, which serves as the negative electrode, thus forming a composite electrode.

[0143] After forming the composite electrode, step A1 further includes welding the aluminum plating layer to the aluminum tab sheet and welding the copper plating layer to the copper-nickel-plated tab sheet, thereby forming a positive electrode tab and a negative electrode tab on the composite electrode.

[0144] The process of preparing the reference electrode sheet includes:

[0145] The reference electrode is a lithium-copper composite strip, with the lithium metal region having an area of ​​70×70mm. The reference electrode sheet is soldered to a copper-plated nickel tab to form the reference electrode tab on the reference electrode sheet.

[0146] The diaphragm is made of 14µm thick polyethylene (PE).

[0147] Step A2 involves assembling the reference electrode, separator, composite electrode, separator, and reference electrode in that order to form a lithium-ion three-electrode battery.

[0148] The specific process includes: assembling the reference electrode sheet, separator, composite electrode sheet, separator and reference electrode sheet in that order, injecting electrolyte and then encapsulating with a 148um thick aluminum-plastic film to complete the preparation of the lithium-ion three-electrode battery.

[0149] After preparing the lithium-ion three-electrode battery, performance testing was conducted. A Newway test cabinet was used to connect the positive and negative electrode tabs for charge-discharge testing; a multi-channel recorder was connected to the positive, negative, and reference electrodes for potential monitoring. The test results are as follows: Figure 6 As shown.

[0150] Comparative Example

[0151] In a comparative embodiment, a lithium-ion three-electrode battery includes:

[0152] Ternary cathode material;

[0153] Negative electrode plate;

[0154] Select a reference electrode sheet with lithium-copper composite strip;

[0155] Choose a PE separator with a thickness of 14µm;

[0156] Choose an aluminum-plastic film with a thickness of 148um;

[0157] An aluminum tab was chosen as the positive electrode tab.

[0158] Copper-plated nickel tabs were selected as the reference electrode tab and the negative electrode tab.

[0159] The electrolyte consists of: 1M LiPF6 (1 mole of lithium hexafluorophosphate), 1:1 EC / DMC (solvents are ethylene carbonate and dimethyl carbonate in a 1:1 ratio), and 10% FEC (additive is 10% fluoroethylene carbonate).

[0160] In the comparative example, the lithium-ion three-electrode battery fabrication process is as follows:

[0161] Step 1: This includes the fabrication of the positive and negative electrodes, the fabrication of the reference electrode sheet, the welding of positive electrode tabs onto the positive electrode sheet, the welding of negative electrode tabs onto the negative electrode sheet, and the welding of reference electrode tabs onto the reference electrode sheet.

[0162] The manufacturing process of ternary cathode plates is as follows:

[0163] A positive electrode slurry was prepared by mixing NCM811 (nickel-cobalt-manganese ratio of 8:1:1), SP (conductive carbon black), and PVDF (polyvinylidene fluoride) in a ratio of 95:2.5:2.5. The positive electrode slurry was then coated onto aluminum foil, with a coating capacity of 9 mAh / cm². 2 The compacted density is 3.5 g / cm³. 3 The material area is 60×60mm in size, forming a ternary cathode sheet.

[0164] The manufacturing process of the negative electrode is as follows:

[0165] A slurry of SiO / C (silicon oxide / carbon), SP (conductive carbon black), and CMC (sodium carboxymethyl cellulose) in a ratio of 90:5:5 was formed to create a negative electrode slurry. This negative electrode slurry was then coated onto copper foil, achieving a coating capacity of 10.8 mAh / cm². 2 The NP ratio is 1.2, and the compacted density is 1.6 g / cm³. 3 The material area is 65×65mm in size, forming a negative electrode sheet.

[0166] The fabrication process of the reference electrode sheet is as follows:

[0167] A lithium-copper composite strip was cut to serve as a reference electrode, with the lithium metal region measuring 1 mm × 10 mm.

[0168] Aluminum tabs are welded onto the positive electrode to form a positive electrode tab, copper-plated nickel tabs are welded onto the negative electrode to form a negative electrode tab, and copper-plated nickel tabs are welded onto the reference electrode to form a reference electrode tab.

[0169] Step two, battery assembly: The battery is assembled in the order of positive electrode, separator, reference electrode, separator, and negative electrode. After injecting electrolyte, it is sealed with aluminum-plastic film to complete the preparation of lithium-ion three-electrode battery.

[0170] After preparing the lithium-ion three-electrode battery, performance testing was conducted. A Newway test cabinet was used to connect the positive and negative electrode tabs for charge-discharge testing; a multi-channel recorder was connected to the positive, negative, and reference electrodes for potential monitoring. The test results are as follows: Figure 6 As shown.

[0171] exist Figure 6 In the examples, the electrode potential curves of the lithium-ion three-electrode battery tested according to the present invention are shown, while the comparative examples show the electrode potential curves tested with a reference electrode placed between the positive and negative electrodes. Figure 6 It can be seen that in the charge-discharge curve of the battery negative to lithium obtained in the comparative example, the voltage is below 0V, indicating a deviation. However, in this embodiment, the voltage on the charge-discharge curve of the battery negative to lithium is always above the voltage on the charge-discharge curve of the battery negative to lithium obtained in the comparative example. In comparison, the charge-discharge measurement using the three-electrode battery structure of the present invention is more accurate.

[0172] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium-ion three-electrode battery, characterized in that, The lithium-ion three-electrode battery is obtained by assembling the reference electrode sheet, separator, composite electrode sheet, separator, and reference electrode sheet in that order. The first surface of the composite electrode is a positive electrode material layer, and the second surface of the composite electrode is a negative electrode material layer; Reference electrode sheets are disposed on both the first and second surfaces facing the composite electrode sheet, and the reference electrode sheets are separated from the composite electrode sheet by a diaphragm; The reference electrode sheet includes a reference electrode current collector and a reference electrode material area, wherein the reference electrode material area is disposed on a first surface of the reference electrode current collector, and the first surface of the reference electrode current collector faces the composite electrode sheet; The composite electrode includes an intermediate insulating layer; The first surface of the intermediate insulating layer is provided with an aluminum plating layer and a first blank area is left. The positive electrode material layer is disposed on the first surface of the aluminum plating layer. The second surface of the intermediate insulating layer is provided with a copper plating layer and a second blank area is left. The negative electrode material layer is disposed on the second surface of the copper plating layer. The first blank area and the second blank area are opposite each other on the left and right; The composite electrode has several through holes that sequentially penetrate the positive electrode material layer, the aluminum plating layer, the intermediate insulating layer, the copper plating layer, and the negative electrode material layer.

2. A lithium-ion three-electrode battery as described in claim 1, characterized in that, The second surface of the reference electrode current collector is provided with a reference electrode tab.

3. A lithium-ion three-electrode battery as described in claim 1, characterized in that, The first surface of the aluminum coating has a third blank area, and the third blank area is connected to a positive electrode tab. The second surface of the copper plating layer has a fourth blank area, and the fourth blank area is connected to the negative electrode tab. The third blank area is positioned vertically opposite to the second blank area; The fourth blank area is positioned vertically opposite to the first blank area.

4. A method for preparing a lithium-ion three-electrode battery, characterized in that, The method for preparing a lithium-ion three-electrode battery as described in any one of claims 1-3 includes the following steps: Step A1: Prepare a composite electrode sheet, a reference electrode sheet, and a separator, wherein the first surface of the composite electrode sheet is a positive electrode material layer, and the second surface of the composite electrode sheet is a negative electrode material layer. Step A2: Assemble the reference electrode sheet, the separator, the composite electrode sheet, the separator, and the reference electrode sheet in that order to obtain the lithium-ion three-electrode battery.

5. The method for preparing a lithium-ion three-electrode battery as described in claim 4, characterized in that, In step A1, the prepared reference electrode sheet includes a reference electrode current collector and a reference electrode material region, wherein the reference electrode material region is disposed on the first surface of the reference electrode current collector; In step A2, during assembly, the first surface of the reference electrode current collector faces the composite electrode.

6. The method for preparing a lithium-ion three-electrode battery as described in claim 5, characterized in that, Step A1 also includes providing a reference electrode tab on the second surface of the reference electrode sheet.

7. The method for preparing a lithium-ion three-electrode battery as described in claim 5, characterized in that, In step A1, the composite electrode sheet prepared includes an intermediate insulating layer; The first surface of the intermediate insulating layer is plated with an aluminum coating and has a first blank area. The positive electrode material layer is disposed on the first surface of the aluminum coating. The second surface of the intermediate insulating layer is plated with a copper plating layer, and a second blank area is left. The negative electrode material layer is disposed on the second surface of the copper plating layer. The first blank area and the second blank area are opposite each other.

8. The method for preparing a lithium-ion three-electrode battery as described in claim 7, characterized in that, In the composite electrode prepared by step A1; The first surface of the aluminum coating has a third blank area. The second surface of the copper plating layer has a fourth blank area. The third blank area is positioned vertically opposite to the second blank area; The fourth blank area is positioned vertically opposite to the first blank area; Step A1 further includes connecting a positive electrode tab to the third blank area of ​​the aluminum plating layer of the composite electrode, and connecting a negative electrode tab to the fourth blank area of ​​the copper plating layer of the composite electrode.

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