Three-electrode lithium ion battery
By depositing a uniform lithium layer on the surface of a copper wire and placing it between the active material layers and in the surface grooves to form a reference electrode, the problems of uneven lithium layer and consumption in the prior art are solved, enabling precise monitoring of the negative electrode potential of the top and bottom layers, and improving the electrochemical performance and safety of the battery.
Patent Information
- Application Number
- CN202520260232.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2026-01-02
- Estimated Expiration
- 2035-02-18
AI Technical Summary
Existing three-electrode lithium-ion batteries consume active lithium during the manufacturing process, resulting in uneven and unstable lithium layers. Dissolution occurs during testing, leading to short service life, inaccurate data detection, and an inability to accurately monitor the potential of the bottom negative electrode.
A uniformly thick lithium layer is pre-plated onto the surface of a copper wire to form first and second reference electrodes, which are located between the first and second active material layers and at the surface groove, respectively, to monitor the negative electrode potential of the bottom and top layers.
This avoids the consumption of active lithium, ensures stable cell capacity, accurately monitors the top and bottom negative electrode potentials, and improves the electrochemical performance and safety of the battery.
Smart Images
Figure CN223757525U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a three-electrode lithium ion battery. BACKGROUND
[0002] The current preparation method of the three-electrode is to wrap a layer of diaphragm outside the copper wire on the surface of the negative electrode, and to electrochemically deposit lithium with different time and different current before testing. This method consumes the active lithium of the battery, and the lithium layer is uneven and unstable, and dissolves in the testing process, has a short service life, and the data detection is inaccurate. At the same time, the double-layer coating only tests the potential of the electrolyte at a certain distance from the top negative electrode surface, which has a certain difference from the actual negative electrode potential, and the actual potential of the bottom negative electrode cannot be detected.
[0003] Therefore, it is urgent to design a three-electrode lithium ion battery which can accurately monitor the potential. SUMMARY
[0004] To solve the above technical problems, the application provides a three-electrode lithium ion battery, a layer of lithium layer with uniform thickness is plated on the surface of the copper wire in advance, so as to avoid consumption of the active lithium of the battery, thereby avoiding the capacity decrease of the battery; the copper wire containing the lithium layer is placed between the first active material layer and the second active material layer to form a first reference electrode, so as to monitor the potential of the bottom negative electrode; the copper wire containing the lithium layer is placed at the surface recess of the second active material layer to form a second reference electrode, so as to accurately monitor the potential of the top negative electrode.
[0005] The application aims to provide a three-electrode lithium ion battery, which comprises a positive electrode sheet, a negative electrode sheet, a reference electrode and a diaphragm; the positive electrode sheet, the negative electrode sheet and the diaphragm are arranged in a stack; the positive electrode sheet and the negative electrode sheet are arranged alternately, and the diaphragm is arranged between adjacent positive electrode sheet and negative electrode sheet;
[0006] The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on the negative electrode current collector; the negative electrode active layer comprises a first active material layer and a second active material layer, the first active material layer is arranged on the negative electrode current collector, and the second active material layer is arranged on the first active material layer;
[0007] The reference electrode comprises a first reference electrode and a second reference electrode; the first reference electrode is arranged between the first active material layer and the second active material layer; and the second reference electrode is arranged on the second active material layer;
[0008] The first reference electrode and the second reference electrode are at least partially located outside the negative electrode sheet.
[0009] In an embodiment of the application, the first reference electrode comprises a first copper wire and a first lithium layer at least partially coated on the surface of the first copper wire.
[0010] In one embodiment of the present application, the first copper wire outside the negative electrode sheet is a bare copper wire.
[0011] In one embodiment of the present application, the diameter of the first copper wire is 40-250 nm, and the length is 100-200 mm; the thickness of the first lithium layer is 50-800 nm.
[0012] In one embodiment of the present application, the second active material layer is provided with a groove along the length direction thereof, and the second reference electrode is arranged in the groove.
[0013] In one embodiment of the present application, the second reference electrode comprises a second copper wire and a second lithium layer at least partially covering the surface of the second copper wire.
[0014] In one embodiment of the present application, the length of the second lithium layer is the same as the length of the groove.
[0015] In one embodiment of the present application, the diameter of the second copper wire is 40-250 nm, and the length is 100-200 mm; the thickness of the second lithium layer is 50-800 nm.
[0016] In one embodiment of the present application, the length of the groove is 30-90 mm; the width is 300-1000 nm, and the depth is 300-1000 nm.
[0017] In one embodiment of the present application, the three-electrode lithium ion battery further comprises a tab assembly; the tab assembly comprises a positive electrode tab, a negative electrode tab and a reference electrode tab; the positive electrode tab is electrically connected with the positive electrode sheet, the negative electrode tab is electrically connected with the negative electrode sheet, and the reference electrode tab is electrically connected with the reference electrode.
[0018] In one embodiment of the present application, the positive electrode tab, the negative electrode tab and the reference electrode tab are arranged at the first end of the three-electrode lithium ion battery.
[0019] Alternatively, the positive electrode tab and the negative electrode tab are arranged at the first end of the three-electrode lithium ion battery, and the reference electrode tab is arranged at the second end of the three-electrode lithium ion battery, and the first end and the second end of the three-electrode lithium ion battery are arranged oppositely.
[0020] The technical solution of the present application has the following advantages compared with the prior art:
[0021] The reference electrode in the three-electrode lithium ion battery of the present application can avoid the deviation of the positive and negative electrode potentials caused by the loss of active lithium, and accurately monitor the top negative electrode potential and the bottom negative electrode potential. BRIEF DESCRIPTION OF DRAWINGS
[0022] In order to make the content of the present application more easily understood, the present application is further described in detail below according to specific embodiments of the present application and in conjunction with the accompanying drawings, in which:
[0023] Figure 1 A schematic view of a negative plate of a three-electrode lithium ion battery of the present application;
[0024] Brief description of the drawings: 1-negative current collector, 2-first active material layer, 3-first copper wire, 4-first lithium layer, 5-second active material layer, 6-second copper wire, 7-second lithium layer. DETAILED DESCRIPTION
[0025] As described in the background, the current preparation of three electrodes is to place a copper wire between two layers of separators and on the surface of the negative electrode, and to electrochemically deposit lithium on the copper wire by adjusting the charging current and time of the battery cell, to obtain a lithium layer, and then to measure the negative potential as a reference electrode. However, the reference electrode consumes active lithium of the battery cell, and the lithium layer is uneven and unstable, and dissolves during the test, has a short service life, and the data detection is inaccurate. In addition, generally only the potential of the electrolyte at a certain distance from the surface of the top negative electrode is tested, which has a certain difference from the actual negative potential, and the actual potential of the bottom negative electrode cannot be detected.
[0026] To solve the above technical problems, the present application provides a three-electrode lithium ion battery, which pre-treats a copper wire with a uniform thickness lithium layer to avoid consumption of active lithium of the battery cell, thereby avoiding capacity reduction of the battery cell; places the copper wire with the lithium layer between a first active material layer 2 and a second active material layer 5 to form a first reference electrode to monitor the potential of the bottom negative electrode; and places the copper wire with the lithium layer at a surface recess of the second active material layer 5 to form a second reference electrode to accurately monitor the potential of the top negative electrode.
[0027] The purpose of the present application is to provide a three-electrode lithium ion battery, which comprises a positive plate, a negative plate, a reference electrode, and a separator; the positive plate, the negative plate, and the separator are arranged in a stack; the positive plate and the negative plate are arranged alternately, and the adjacent positive plate and negative plate are both provided with the separator;
[0028] The negative plate comprises a negative current collector 1 and a negative active layer arranged on the negative current collector 1; the negative active layer comprises a first active material layer 2 and a second active material layer 5, the first active material layer 2 is arranged on the negative current collector 1, and the second active material layer 5 is arranged on the first active material layer 2;
[0029] The reference electrode comprises a first reference electrode and a second reference electrode; the first reference electrode is arranged between the first active material layer 2 and the second active material layer 5; and the second reference electrode is arranged on the second active material layer 5.
[0030] The first reference electrode and the second reference electrode are at least partially located outside the negative electrode sheet.
[0031] In an embodiment of the present application, the first reference electrode comprises a first copper wire 3 and a first lithium layer 4 at least partially covering the surface of the first copper wire 3.
[0032] In an embodiment of the present application, the first copper wire 3 located outside the negative electrode sheet is a bare copper wire.
[0033] In an embodiment of the present application, the diameter of the first copper wire 3 is 40-250 nm, and the length is 100-200 mm; and the thickness of the first lithium layer 4 is 50-800 nm.
[0034] In an embodiment of the present application, the second active material layer 5 is provided with a groove along the length direction, and the second reference electrode is arranged in the groove; the groove structure not only can increase the storage amount of electrolyte, ensure that the electrolyte can be evenly distributed on the electrode surface, thereby improving the electrochemical performance of the battery, but also can increase the electrode surface area and enhance the heat dissipation capacity, effectively curb the temperature rise during fast charging.
[0035] In an embodiment of the present application, the second reference electrode comprises a second copper wire 6 and a second lithium layer 7 at least partially covering the surface of the second copper wire 6; the lithium layer can avoid the additional consumption of active lithium in the battery cell, thereby effectively preventing the capacity decline of the battery cell.
[0036] In an embodiment of the present application, the length of the second lithium layer 7 is the same as the length of the groove.
[0037] In an embodiment of the present application, the diameter of the second copper wire 6 is 40-250 nm, which can ensure moderate contact area between the copper wire and the active material layer, guaranteeing good electrical connection and not affecting the overall structure of the electrode due to excessive contact area; in addition, this diameter range helps to reduce stress concentration of the copper wire during battery charging and discharging, thereby improving the mechanical stability of the electrode; the length is 100-200 mm, which can ensure that the reference electrode covers enough electrode area, thereby achieving comprehensive monitoring of the electrode potential; the thickness of the second lithium layer 7 is 50-800 nm; within this thickness range, not only can good electrical connection between the copper wire and the active material layer be ensured, improving the conductivity of the electrode, but also the excessive growth of lithium dendrites can be avoided, thereby reducing the risk of internal short circuit of the battery, in addition, this thickness range helps to optimize the diffusion of lithium ions on the electrode surface, reducing electrode polarization.
[0038] In an embodiment of the present application, the length of the groove is 30-90 mm; the width is 300-1000 nm, and the depth is 300-1000 nm; if the length of the groove is too short, the second reference electrode is only partially placed inside the battery cell, which is difficult to place and cannot accurately detect the potential; if the length is too long, the second reference electrode almost covers the second active material layer, even with the risk of out of the separator, thereby causing short circuit and reducing safety performance. Under this groove specification, enough space can be provided for the expansion of the negative electrode sheet, thereby slowing down the extrusion deformation of the positive electrode protrusion caused by the expansion of the negative electrode.
[0039] In an embodiment of the present application, the type of the negative current collector 1 is not specifically limited and can be selected according to actual needs. In some embodiments, the negative current collector 1 is selected from copper foil, carbon-coated copper foil, or a polymer conductive film.
[0040] In an embodiment of the present application, the raw material composition of the negative active layer includes a negative active material, a conductive agent, and a binder.
[0041] Further, the type and content of the negative active material are not specifically limited and can be selected according to actual needs. In some embodiments, the negative active material is selected from one or more of hard carbon, soft carbon, natural graphite, artificial graphite, and silicon-carbon.
[0042] Further, the type and content of the conductive agent are not specifically limited and can be selected according to actual needs. In some embodiments, the conductive agent includes one or more of conductive carbon black, carbon nanotubes, acetylene black, graphene, Ketjen black, and carbon nanofibers. It should be understood that other conductive agents that can achieve the functions of the present application can be selected according to specific needs without limitation as long as the spirit of the present application is not violated.
[0043] Further, the kind and content of the binder are not particularly limited and can be selected according to actual needs. In some embodiments, the binder comprises one or more of polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, sodium carboxymethyl cellulose, polymethacrylamide, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyamide, polyimide, polyacrylate, styrene butadiene rubber, sodium alginate, chitosan, polyethylene glycol, guar gum, and the like.
[0044] In an embodiment of the present application, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer disposed on the positive electrode current collector, wherein the positive electrode active layer comprises a positive electrode active material, a conductive agent, and a binder. The positive electrode sheet can be prepared by a method commonly used in the art, and an illustrative preparation method is as follows: preparing an electrode slurry comprising the positive electrode active material, the binder, and the conductive agent in a certain proportion, then coating the electrode slurry on at least one surface of the positive electrode current collector, drying, and pressing to obtain the positive electrode sheet.
[0045] Further, the kind and content of the positive electrode active material are not particularly limited and can be selected according to actual needs. In some embodiments, the positive electrode active material is selected from one or more of lithium iron phosphate, ternary lithium nickel cobalt manganese oxide, lithium manganese iron oxide, lithium cobalt oxide, and lithium manganate. 锂
[0046] Further, the kind of the positive electrode current collector is not particularly limited and can be selected according to actual needs. In some embodiments, the positive electrode current collector is selected from an aluminum foil, a nickel foil, or a high-molecular conductive film. The kind of the conductive agent and the binder in the positive electrode sheet is described above with reference to the negative electrode sheet, and the present application will not be described again.
[0047] In an embodiment of the present application, the three-electrode lithium ion battery further comprises a tab assembly; the tab assembly comprises a positive electrode tab, a negative electrode tab, and a reference electrode tab; the positive electrode tab is electrically connected to the positive electrode sheet, the negative electrode tab is electrically connected to the negative electrode sheet, and the reference electrode tab is electrically connected to the reference electrode.
[0048] In an embodiment of the present application, the positive electrode tab, the negative electrode tab, and the reference electrode tab are disposed at a first end of the three-electrode lithium ion battery.
[0049] Alternatively, the positive electrode tab and the negative electrode tab are disposed at a first end of the three-electrode lithium ion battery, and the reference electrode tab is disposed at a second end of the three-electrode lithium ion battery, wherein the first end and the second end of the three-electrode lithium ion battery are oppositely disposed.
[0050] In an embodiment of the present application, the three-electrode lithium ion battery further comprises an electrolyte and a separator.
[0051] Further, the electrolyte includes one or more of organic liquid electrolyte, organic solid electrolyte, solid ceramic electrolyte, gel electrolyte, etc. Preferably, the electrolyte is an organic liquid electrolyte obtained by dissolving a lithium salt in a non-aqueous organic solvent; wherein the lithium salt includes one or more of lithium difluorophosphate, lithium hexafluorophosphate, lithium difluoro-oxalate-phosphate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium tetrafluoroborate and lithium difluoro-oxalate-borate. The non-aqueous organic solvent can include one or more of cyclic carbonates, chain carbonates, carboxylic acid esters. The cyclic carbonates can be selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone; the chain carbonates can be selected from one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl acetate, ethyl acetate, ethyl propionate, etc.
[0052] Further, the separator film is polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), polyvinylidene fluoride (PVDF) or non-woven fabric, their multi-layer composite films and modified separator films such as ceramic modified, PVDF modified, etc. can be selected according to actual needs.
[0053] It should be understood that the preparation method of the positive electrode sheet, the separator film and the electrolyte in the present application can select other preparation methods that can realize the functions of the present application according to specific needs without departing from the spirit of the present application, and is not limited thereto. In one embodiment of the method for manufacturing a lithium ion battery, the preparation method comprises: winding, folding or stacking the above-mentioned negative electrode sheet, separator film and positive electrode sheet in sequence to form an electrode assembly, placing the electrode assembly in, for example, an aluminum plastic film, and injecting the electrolyte, followed by vacuum packaging, standing, formation, shaping and other processes to obtain a lithium ion battery.
[0054] The present application will be further described in conjunction with the drawings and specific examples, so that those skilled in the art can better understand the present application and implement it, but the examples are not limiting to the present application.
[0055] In the present application, unless otherwise specified, the preparation of the first reference electrode and the second reference electrode (copper wire containing lithium layer) used in the examples and comparative examples of the present application specifically includes the following steps: first, the copper wire is immersed in concentrated sulfuric acid for 20 min to treat the surface oxide layer; then it is immersed in a lithium solution to make lithium uniformly adhere to the surface of the copper wire, and the copper wire containing lithium layer is obtained after drying treatment.
[0056] Example 1
[0057] The three-electrode lithium ion battery of the embodiment comprises a positive electrode sheet, a negative electrode sheet, a reference electrode and a separator; the positive electrode sheet, the negative electrode sheet and the separator are arranged in a stack and an electrode tab assembly; the positive electrode sheet and the negative electrode sheet are arranged alternately, and the separator is arranged between adjacent positive electrode sheet and negative electrode sheet;
[0058] The negative electrode sheet comprises a negative electrode current collector 1 and a negative electrode active layer arranged on the negative electrode current collector 1; the negative electrode active layer comprises a first active material layer 2 and a second active material layer 5, the first active material layer 2 is arranged on the negative electrode current collector 1, and the second active material layer 5 is arranged on the first active material layer 2; Figure 1
[0059] The reference electrode comprises a first reference electrode and a second reference electrode; the first reference electrode and the second reference electrode are at least partially located outside the negative electrode sheet, the first copper wire 3 located outside the negative electrode sheet is a bare copper wire; the first reference electrode is arranged between the first active material layer 2 and the second active material layer 5; and the second reference electrode is arranged on the second active material layer 5;
[0060] The negative electrode active material artificial graphite, the conductive agent conductive carbon black and the binder polyacrylic acid are mixed in a mass ratio of 97:1:2, deionized water is added and stirred to form a first negative electrode slurry which is uniform and stable; the negative electrode active material artificial graphite, the conductive agent conductive carbon black and the binder polyacrylic acid are mixed in a mass ratio of 95.5:2.5:2, deionized water is added and stirred to form a second negative electrode slurry which is uniform and stable; the first negative electrode slurry and the second negative electrode slurry are uniformly coated on the negative electrode current collector 1 (copper foil with a thickness of 6 μm) by double die extrusion coating, and the first reference electrode is placed at the extrusion outlet; after cold pressing at a pressure of 50 MPa for 5 min at room temperature, the first active material layer 2 and the second active material layer 5 containing the first reference electrode are obtained; wherein the first reference electrode comprises a first copper wire 3 and a first lithium layer 4 at least partially coated on the surface of the first copper wire 3, the diameter of the first copper wire 3 is 200 nm, and the length is 100 mm; the thickness of the first lithium layer 4 is 100 nm, and the length is 50 mm;
[0061] A groove is formed in the second active material layer 5 along its length direction by using a laser (laser processing parameters P=3.5 W, τ=200 fs), and then the second reference electrode is arranged in the groove to form the second active material layer 5 containing the second reference electrode, thereby obtaining the negative electrode sheet; wherein the width W of the groove is 300 nm, the depth H is 300 nm, and the length L is 50 mm; the second reference electrode comprises a second copper wire 6 and a second lithium layer 7 at least partially coated on the surface of the second copper wire 6; the diameter of the second copper wire 6 is 200 nm, and the length is 100 mm; the thickness of the second lithium layer 7 is 100 nm, and the length is 50 mm, and the length of the second lithium layer 7 is the same as the length of the groove.
[0062] The positive electrode sheet: the positive electrode active material is lithium iron phosphate LFP, the conductive agent is conductive carbon black and carbon nanotube (mass ratio 2:1), the binder is PVDF5130, and the positive electrode current collector is 13 μm aluminum foil; the positive electrode active material, the conductive agent and the binder are mixed in a mass ratio of 95:2:3, then a solvent NMP is added and stirred to form a positive electrode slurry which is uniformly mixed and stable, the positive electrode slurry is uniformly coated on the positive electrode current collector, and the positive electrode sheet is obtained after drying and rolling.
[0063] The isolation film: the isolation film base film is a polypropylene film with a thickness of 9 μm, and the two sides are coated with PVDF with a thickness of 3 μm, and the positive electrode side is coated with an aluminum oxide layer with a thickness of 3 μm.
[0064] The tab assembly: including a positive electrode tab, a negative electrode tab and a reference electrode tab; the positive electrode tab is electrically connected with the positive electrode sheet, the negative electrode tab is electrically connected with the negative electrode sheet, and the reference electrode tab is electrically connected with the reference electrode; wherein the positive electrode tab and the negative electrode tab are arranged at the first end of the three-electrode lithium ion battery, the reference electrode tab is arranged at the second end of the three-electrode lithium ion battery, and the first end and the second end of the three-electrode lithium ion battery are oppositely arranged.
[0065] The electrolyte: ethylene carbonate, methyl ethyl carbonate and diethyl carbonate are mixed in a volume ratio of 1.5:1:0.5, then LiPF6 which is fully dried is dissolved in the mixed organic solvent in a proportion of 1.2 mol / L to obtain the electrolyte.
[0066] The assembly of the three-electrode lithium ion battery: the positive electrode sheet, the isolation film, the negative electrode sheet containing the reference electrode, and the isolation film are arranged in sequence to obtain the battery cell; the tabs are ultrasonically welded, the top side of the aluminum plastic film is sealed, the water is removed by drying, the electrolyte is injected after the second sealing, the electrolyte is injected into the dried battery cell, and the three-electrode lithium ion battery is obtained after formation and capacity distribution.
[0067] Example 2
[0068] The same as example 1, except that the width W of the groove = the depth H = 745 nm, and the length L = 45 mm (the thickness of the second lithium layer is the width of the groove minus the diameter of the copper wire).
[0069] Example 3
[0070] The same as example 1, except that the width W of the groove = the depth H = 600 nm, and the length L = 55 mm.
[0071] Example 4
[0072] The same as example 1, except that the width W of the groove = the depth H = 350 nm, and the length L = 53 mm.
[0073] Example 5
[0074] Example 1 except that the width W = depth H = 700 nm and the length L = 48 mm.
[0075] Example 6
[0076] Example 1 except that the width W = depth H = 450 nm and the length L = 52 mm.
[0077] Example 7
[0078] Example 1 except that the width W = depth H = 480 nm and the length L = 49 mm.
[0079] Example 8
[0080] Example 1 except that the width W = depth H = 500 nm and the length L = 43 mm.
[0081] Example 9
[0082] Example 1 except that the width W = depth H = 950 nm and the length L = 55 mm.
[0083] Example 10
[0084] Example 1 except that the width W = depth H = 900 nm and the length L = 60 mm.
[0085] Example 11
[0086] Example 1 except that the width W = depth H = 825 nm and the length L = 58 mm.
[0087] Example 12
[0088] Example 1 except that the width W = depth H = 425 nm and the length L = 54 mm.
[0089] Comparative Example 1
[0090] Example 1 except that no groove is provided, i.e. no second reference electrode is provided.
[0091] Performance Test 1
[0092] Three-electrode lithium ion batteries of Examples 1-12 and Comparative Example 1 were subjected to capacity, voltage monitoring tests:
[0093] (1) Capacity test: 0.33C rate constant current charging to 3.65V in 25℃ oven, 3.65V constant voltage charging to current cut-off 0.05C, standing for 30min, 0.33C constant current discharging to 2.5V, standing, and cycling three times for three-electrode lithium ion battery, taking the capacity of the last week as the actual capacity Co of the battery.
[0094] (2) Positive and negative electrode voltage monitoring: 0.33C0 constant current constant voltage charging to 100% SOC for three-electrode lithium ion battery, monitoring the voltage difference between positive electrode and reference electrode, the voltage difference between negative electrode and reference electrode, and the voltage difference between positive electrode and negative electrode;
[0095] The relevant test results are shown in Table 1:
[0096] Table 1
[0097]
[0098] As can be seen from Table 1, the width and depth of the groove have certain influence on the actual capacity of the battery, and are negatively correlated therewith. Since lithium ion intercalation lithium goes from the top layer to the bottom layer of the negative electrode, the lithium concentration at the bottom layer is greater than that at the top layer and forms a gradient, the negative electrode potential is lower than the second reference potential and has smaller fluctuation range and higher accuracy. By observing the positive electrode potential relative to the SOC curve of the first / second reference electrode and the negative electrode potential relative to the SOC curve of the first / second reference electrode, the fluctuation range is smaller, the accuracy is higher, and the top / bottom layer negative electrode potential can be monitored simultaneously.
[0099] Obviously, the above embodiments are merely examples for the purpose of clear illustration, and are not intended to limit the embodiments. Other different forms of changes or variations can be made by those of ordinary skill in the art on the basis of the above description. It is not necessary or possible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.
Claims
1. A three-electrode lithium-ion battery, characterized by, The three-electrode lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, a reference electrode and a separator; the positive electrode sheet, the negative electrode sheet and the separator are arranged in a stack; the positive electrode sheet and the negative electrode sheet are arranged alternately, and the separator is arranged between adjacent positive electrode sheet and negative electrode sheet. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on the negative electrode current collector; the negative electrode active layer comprises a first active material layer and a second active material layer; the first active material layer is arranged on the negative electrode current collector, and the second active material layer is arranged on the first active material layer. The reference electrode comprises a first reference electrode and a second reference electrode; the first reference electrode is arranged between the first active material layer and the second active material layer; and the second reference electrode is arranged on the second active material layer. The first reference electrode and the second reference electrode are at least partially located outside the negative electrode sheet.
2. The three-electrode lithium-ion battery of claim 1, wherein, The first reference electrode comprises a first copper wire and a first lithium layer at least partially covering the surface of the first copper wire.
3. The three-electrode lithium-ion battery of claim 2, wherein, The first copper wire located outside the negative electrode sheet is a bare copper wire.
4. The three-electrode lithium-ion battery of claim 2, wherein, The diameter of the first copper wire is 40-250 nm, and the length is 100-200 mm; the thickness of the first lithium layer is 50-800 nm.
5. The three-electrode lithium-ion battery of claim 1, wherein, The second active material layer is provided with a groove along the length direction thereof, and the second reference electrode is arranged in the groove.
6. The three-electrode lithium-ion battery of claim 5, wherein, The second reference electrode comprises a second copper wire and a second lithium layer at least partially covering the surface of the second copper wire.
7. The three-electrode lithium-ion battery of claim 6, wherein, The length of the second lithium layer is the same as the length of the groove.
8. The three-electrode lithium-ion battery of claim 6, wherein, The diameter of the second copper wire is 40-250 nm, and the length is 100-200 mm; the thickness of the second lithium layer is 50-800 nm.
9. The three-electrode lithium-ion battery of claim 5, wherein, The length of the groove is 30-90 mm; the width is 300-1000 nm, and the depth is 300-1000 nm.
10. The three-electrode lithium-ion battery of claim 1, wherein, The three-electrode lithium ion battery further comprises a tab assembly; the tab assembly comprises a positive electrode tab, a negative electrode tab and a reference electrode tab; the positive electrode tab is electrically connected to the positive electrode sheet, the negative electrode tab is electrically connected to the negative electrode sheet, and the reference electrode tab is electrically connected to the reference electrode.