Characterization method for gram volumes of positive electrode and negative electrode of full battery cell of lithium ion battery

Abstract

The invention provides a lithium ion battery full-cell positive and negative electrode gram volume characterization method. The method comprises the following steps: assembling a positive plate and a lithium plate into a simple positive electrode cell, assembling a negative plate and the lithium plate into a simple negative electrode cell, and assembling the positive plate and the negative plate into a simple full-cell cell; sequentially connecting the negative simple battery cell, the full-battery-cell simple battery cell and the positive simple battery cell in series; then the series circuit is charged according to a full-cell charging mode, and charging is ended after full charging; recording the charging capacity C0, and calculating the charging gram capacity of the positive and negative electrodes of the whole battery core; and finally, discharging the series circuit in a full-cell discharging mode, and ending discharging after full discharging. And recording the discharge capacity C1, and calculating the discharge gram capacity of the positive and negative electrodes of the full cell. According to the invention, the positive simple half cell, the full-cell simple half cell and the negative simple half cell are connected in series, so that the positive and negative gram volumes and the positive and negative potentials of the full cell of the lithium ion battery can be obtained after charging and discharging.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a method for characterizing the gram capacity of positive and negative electrodes of a full-cell lithium-ion battery. Background Art

[0002] A full lithium-ion battery cell is relative to a "half-charged" button cell. It refers to a cell consisting of a designed positive electrode and a designed negative electrode, while a "half-charged" button cell consists of a designed positive electrode or negative electrode and a lithium sheet.

[0003] When designing a full-cell lithium-ion battery, the actual gram capacity of the positive and negative electrodes in the full-cell is of great significance, and determines the actual battery product's first effect, capacity, CB value, energy density and other important indicators. If the gram capacity input is inaccurate at the beginning of the design, it will directly lead to substandard battery cell parameters, unqualified products, and a lot of waste of resources and time. The conventional method of characterizing gram capacity is button cells, but because the full cell and button cell systems are different, the polarization level is also different, and the gram capacity generally has deviations, especially in the silicon system. The three-electrode method can characterize the gram capacity more accurately, but the operation is cumbersome, time-consuming, and has a high failure rate and low efficiency. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present application provides a method for characterizing the gram capacity of the positive and negative electrodes of a full lithium-ion battery cell. The present application ingeniously uses a simple method of connecting cells in series to characterize the gram capacity of a full lithium-ion battery cell, solving the problem of large deviations in the gram capacity value of traditional button-type cells, and is simpler and faster than the three-electrode characterization method, with a higher success rate.

[0005] The present application provides a method for characterizing the gram capacity of the positive and negative electrodes of a full-cell lithium-ion battery, including characterizing the charging gram capacity and the discharging gram capacity of the positive and negative electrodes of the full-cell lithium-ion battery, and the characterization method comprises the following steps:

[0006] S1, preparation before characterization: assemble the positive electrode sheet and the lithium sheet into a positive electrode simple battery cell, assemble the negative electrode sheet and the lithium sheet into a negative electrode simple battery cell, and assemble the positive electrode sheet and the negative electrode sheet into a full-cell simple battery cell; connect the negative electrode simple battery cell, the full-cell simple battery cell, and the positive electrode simple battery cell in series in sequence;

[0007] S2, charge the series circuit in the full-cell charging mode, and end the charging after the full charge; record the charging capacity C0, the full-cell positive electrode charging capacity in grams = charging capacity C0 / weight of the positive electrode active material in the full-cell simple battery cell; the full-cell negative electrode charging capacity in grams = charging capacity C0 / weight of the negative electrode active material in the full-cell simple battery cell;

[0008] S3, discharge the series circuit in the full-cell discharge mode, and end the discharge after full discharge; record the discharge capacity C1, the full-cell positive electrode discharge capacity in grams = discharge capacity C1 / the weight of the positive electrode active material in the full-cell simple battery cell; the full-cell negative electrode discharge capacity in grams = discharge capacity C1 / the weight of the negative electrode active material in the full-cell simple battery cell.

[0009] As a preferred solution, the simple battery cell includes but is not limited to button cells, single-layer laminated cells and multi-layer laminated cells.

[0010] As a preferred solution, the negative electrode simple battery cell, the full battery cell simple battery cell, and the positive electrode simple battery cell are sequentially connected in series in the order of lithium sheet, negative electrode sheet, positive electrode sheet, negative electrode sheet, positive electrode sheet, and lithium sheet.

[0011] As a preferred solution, the full charge voltage of the full-cell simple battery cell is 3.5V-4.5V.

[0012] As a preferred solution, the charging process of the full-cell simple battery is 0.01-10C CC to 3.5-4.5V; CV to 0.05C.

[0013] As a preferred solution, the fully charged and fully discharged voltage of the full-cell simple battery cell is 2V-3V.

[0014] As a preferred solution, the discharge process of the full-cell simple battery is 0.01-10C DC to 2-3V.

[0015] As a preferred solution, after charging is completed, record the voltage V of the positive electrode simple battery cell. 正 , the voltage of the negative electrode simple battery cell is V 负 , then V 正 It is the positive electrode potential of the full-cell simple battery after charging, V 负 It is the negative electrode potential of the full-cell simple battery after charging.

[0016] As a preferred solution, after the discharge is completed, the voltage V' of the positive electrode simple battery cell is recorded. 正 , the voltage of the negative electrode simple battery cell V' 负 , then V′ 正 It is the positive electrode potential of the simple battery cell with full battery, V' 负 That is the negative electrode potential of the full-cell simple battery.

[0017] The present application adopts a method of connecting a simple positive half-cell, a simple full battery half-cell, and a simple negative half-cell in series, and after charging and discharging, the positive and negative electrode gram capacity and the positive and negative electrode potential of the full lithium-ion battery cell can be obtained. The method of the present application is simple, fast, and has a high success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 Schematic diagram of the method for characterizing the gram capacity of the positive and negative electrodes of the full-cell lithium-ion battery of the present application. DETAILED DESCRIPTION

[0020] For simplicity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0021] In the description herein, unless otherwise specified, “above” and “below” include the number.

[0022] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0023] The present application is further described below in conjunction with specific implementations. It should be understood that these specific implementations are only used to illustrate the present application and are not used to limit the scope of the present application.

[0024] The characterization method of the positive and negative electrode gram capacity of the full cell of the lithium ion battery of the present application includes the characterization of the charging gram capacity and the discharging gram capacity of the positive and negative electrodes of the full cell, and the steps of the characterization method are as follows:

[0025] S1, preparation before characterization: assemble the positive electrode sheet and the lithium sheet into a positive electrode simple battery cell, assemble the negative electrode sheet and the lithium sheet into a negative electrode simple battery cell, and assemble the positive electrode sheet and the negative electrode sheet into a full-cell simple battery cell; connect the negative electrode simple battery cell, the full-cell simple battery cell, and the positive electrode simple battery cell in series in sequence;

[0026] S2, charge the series circuit in the full-cell charging mode, and end the charging after the full charge; record the charging capacity C0, which is the capacity C0 of the positive and negative electrodes of the full-cell simple battery, that is, the charging capacity in the full-cell simple battery. Then the full-cell positive electrode charging capacity in grams = charging capacity C0 / weight of the positive electrode active material in the full-cell simple battery; the full-cell negative electrode charging capacity in grams = charging capacity C0 / weight of the negative electrode active material in the full-cell simple battery;

[0027] S3, discharge the series circuit in the full-cell discharge mode, and end the discharge after the full charge is fully discharged; record the discharge capacity C1, which is the capacity C1 of the positive and negative electrodes of the full-cell simple battery, that is, the discharge capacity in the full-cell simple battery. Then the full-cell positive electrode discharge gram capacity = discharge capacity C1 / weight of the positive electrode active material in the full-cell simple battery; the full-cell negative electrode discharge gram capacity = discharge capacity C1 / weight of the negative electrode active material in the full-cell simple battery.

[0028] According to some embodiments of the present application, in step S2, a voltmeter can be used to monitor the voltage of the full-cell simple battery cell; the present application does not restrict the charging process, as long as it is fully charged in the end. For example, the charging process is 0.01-10C CC to 3.5-4.5V; CV to 0.05C (where C is the capacity of the battery cell; the charging rate here can be adjusted, generally between 0.01 and 10C, according to actual needs; the full charge voltage is also, currently the full charge voltage of lithium batteries is between 3.5-4.5V, so just charge to the full charge voltage).

[0029] According to some embodiments of the present application, in step S3, a voltmeter can be used to monitor the voltage of the full-cell simple battery cell; the present application does not restrict the discharge process, as long as it is fully discharged in the end. For example, the discharge process is 0.01-10C DC to 2-3V (where C is the capacity of the battery cell; the discharge rate here can be adjusted, generally between 0.01 and 10C, according to actual needs; the full discharge voltage is also, currently the full discharge voltage of lithium batteries is between 2-3V, so just discharge to the full discharge voltage).

[0030] According to some embodiments of the present application, the simple battery cell form in the present application includes but is not limited to button cells, single-layer laminated cells and multi-layer laminated cells. For example, button cells are used in Example 1 to obtain positive button cells, negative button cells and full-power button cells.

[0031] This application characterizes the actual thermodynamic capacity of the positive and negative electrodes in a full-cell lithium-ion battery, as well as the irreversible lithium loss, through simple cell forms such as buckle cells, single-layer stacking, and multi-layer stacking.

[0032] According to some embodiments of the present application, the negative electrode simple battery cell, the full battery cell simple battery cell, and the positive electrode simple battery cell are sequentially connected in series in the order of lithium sheet, negative electrode sheet, positive electrode sheet, negative electrode sheet, positive electrode sheet, and lithium sheet.

[0033] The present application does not limit the preparation of the positive and negative electrodes of lithium-ion batteries. Those skilled in the art can use the raw materials commonly used in the prior art and complete the preparation of the positive and negative electrodes of lithium-ion batteries according to the preparation methods commonly used in the prior art. As long as the prepared positive and negative electrodes are characterized according to the method of the present application, the purpose of the present application can be achieved, that is, the characterization of the gram capacity of the positive and negative electrodes of the full cell of the lithium-ion battery can be achieved.

[0034] In some embodiments, the positive electrode described in the present application includes a positive electrode active material, a conductive agent, and a binder.

[0035] In some embodiments, the negative electrode described in the present application includes a negative electrode active material, a conductive agent, and a binder.

[0036] In some embodiments, the positive electrode active material includes, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds. The lithium transition metal oxide may include, but is not limited to, one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium manganese cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. The lithium-containing phosphate with an olivine structure may include, but is not limited to, one or more of lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their modified compounds.

[0037] In some embodiments, the negative electrode active material includes but is not limited to: graphite, carbon material, silicon-based material, a mixture of silicon-based material and graphite material, metal oxides, tin-based materials. For example, silicon-based composite materials include but are not limited to silicon-carbon composite materials, silicon-metal oxide composite materials, silicon alloy composite materials, wherein the mass content of silicon in the composite material is 1-85wt.%. For example, metal oxides include but are not limited to iron oxide, lithium titanate, copper oxide, etc., which are regarded as all metal oxides that can be used for lithium extraction and storage.

[0038] In some embodiments, the conductive agent includes, but is not limited to, metal-based materials, carbon-based materials, conductive polymers, and mixtures thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, nickel, copper, aluminum, or silver. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, acetylene black, Ketjen black, carbon black, carbon fiber, or any combination thereof. In some embodiments, the conductive polymer is a polyphenylene derivative.

[0039] In some embodiments, the binder includes but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, ethylene oxide-containing polymers, carboxylated polyvinyl chloride, polyvinyl pyrrolidone, polyurethane, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon, etc.

[0040] The lithium-ion battery of the present application also includes a diaphragm and an electrolyte. The present application does not limit the diaphragm and the electrolyte, and those skilled in the art can select diaphragms and electrolytes commonly used in the prior art.

[0041] In some embodiments, the diaphragm includes a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, a film or a composite film having a porous structure, and the material of the substrate layer includes at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite film can be selected.

[0042] A surface treatment layer is disposed on at least one surface of the substrate layer. The surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic layer.

[0043] The inorganic layer includes inorganic particles and a binder, wherein the inorganic particles include at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate. The binder includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.

[0044] The polymer layer contains polymers, and the polymer material includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly(vinylidene fluoride-hexafluoropropylene).

[0045] In some embodiments, the electrolyte includes a lithium salt and a solvent.

[0046] In some embodiments, the lithium salt includes, but is not limited to, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalatoborate), or lithium difluorooxalatoborate.

[0047] In some embodiments, the solvent can be selected from one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0048] According to some embodiments of the present application, the test voltage range of the full-cell simple battery is 2V-4.5V.

[0049] In steps S2 and S3, when charging the series circuit, lithium ions move from the negative electrode to the negative electrode, from the fully charged positive electrode to the negative electrode, and from the positive electrode to the lithium electrode. When discharging the series circuit, the opposite is true.

[0050] According to some embodiments of the present application, in step S2, after charging is completed, the voltage V of the positive electrode simple battery cell can also be recorded. 正 , the voltage of the negative electrode simple battery cell is V 负 , then V 正 It is the positive electrode potential of the full-cell simple battery after charging, V 负 It is the negative electrode potential of the full-cell simple battery after charging.

[0051] In step S3, after the discharge is completed, the voltage V′ of the positive electrode simple battery cell can also be recorded. 正 , the voltage of the negative electrode simple battery cell V' 负 , then V′ 正 It is the positive electrode potential of the full-cell simple battery after discharge, V' 负 It is the negative electrode potential of the full-cell simple battery after discharge.

[0052] This application simulates the state of the positive and negative electrodes in a full battery. In a series circuit, the amount of electricity passed through the full-cell simple battery, the positive electrode simple battery, and the negative electrode simple battery is the same. After the discharge is completed, the positive electrode of the full-cell simple battery and the positive electrode in the half-charged battery are in the same state. Therefore, the potential of the positive electrode simple battery can be used to equate the positive electrode potential in the full-cell simple battery, that is, the potential of the positive electrode simple battery is the actual positive electrode potential in the full-charged state. The same applies to charging, where the negative electrode is the same as the positive electrode.

[0053] Example 1

[0054] The simple battery cell used in this embodiment is a button battery. The full charge voltage of the simple battery cell of the full battery cell in this embodiment is 4.2V, and the full discharge voltage is 2.5V, so the test voltage range of the simple battery cell of the full battery cell is 2.5V-4.2V.

[0055] Figure 1 This is a schematic diagram of the characterization method of the positive and negative electrode gram capacity of the full-cell lithium-ion battery of the present application. In the figure, the negative electrode is half-charged / / fully charged / / positive electrode is half-charged and charged in series.

[0056] The characterization method steps of the positive and negative electrode gram capacity of the full battery cell of this application are as follows:

[0057] 1 Preparation before characterization:

[0058] The positive electrode uses a conventional ternary lithium positive electrode roll-pressed positive electrode sheet, and the negative electrode uses a 20% silicon-doped + 80% graphite roll-pressed negative electrode sheet; the positive, negative and lithium sheets are 14mm diameter discs, and the separator uses a conventional PE separator. The positive electrode sheet and the lithium sheet are assembled into a positive electrode buckle, the negative electrode sheet and the lithium sheet are assembled into a negative electrode half-charge, and the positive electrode sheet and the negative electrode sheet are assembled into a full-charge buckle. Then the negative electrode buckle, full-charge buckle, and positive electrode buckle are connected in series in sequence, specifically in the order of lithium sheet, negative electrode sheet, positive electrode sheet, negative electrode sheet, positive electrode sheet, and lithium sheet.

[0059] 2 Determination of full cell charge and discharge capacity:

[0060] The series circuit is charged and discharged, and the voltage range of the full-cell (i.e. fully charged) test is 2.5V-4.2V.

[0061] The specific test method is:

[0062] 2.1 Determination of the charging capacity of the positive and negative electrodes of the full battery cell

[0063] Charge in full-cell mode, and stop charging when the voltage across the full-cell buckle reaches 4.2V; record the charging capacity C0 and the positive buckle voltage V 正 , negative electrode buckling voltage V 负 Full cell positive electrode charge capacity in grams = charge capacity C0 / full cell positive electrode active material weight; full cell negative electrode charge capacity in grams = charge capacity C0 / full cell negative electrode active material weight; V 正 It is the positive electrode potential of the full cell after charging, V 负 It is the negative electrode potential of the full cell after charging.

[0064] The charging process of the above full-power buckle is: 0.33C CC to 4.2V; CV to 0.05C.

[0065] 2.2 Determination of discharge capacity of positive and negative electrodes of full battery cell

[0066] After charging according to the method in 2.1, discharge according to the full-cell discharge method, and discharge until the voltage across the full-charge buckle is 2.5V, then end the discharge; record the discharge capacity C1 and the positive buckle voltage V' 正 , negative electrode buckling voltage V′ 负The gram capacity of the positive electrode of the whole battery cell = discharge capacity C1 / weight of the active material of the positive electrode of the whole battery cell; the gram capacity of the negative electrode of the whole battery cell = discharge capacity C1 / weight of the active material of the negative electrode of the whole battery cell; V′ 正 That is, the positive electrode potential of the full cell after discharge, V′ 负 It is the negative electrode potential of the entire cell after discharge.

[0067] The discharge process of the above full-power button is: 0.33C DC to 2.5V.

[0068] Comparative Example 1

[0069] The method of characterizing the gram capacity of the positive and negative electrodes of the full battery cell using the three-electrode method is as follows:

[0070] Connect the positive and negative electrodes of the three-electrode battery to the charger and discharge machine, and perform charge and discharge to test the capacity;

[0071] The positive electrode and negative electrode of the three-electrode battery and their reference electrode were connected to an electrochemical workstation, and the surface of the reference electrode was first plated with lithium;

[0072] Connect the positive and negative electrodes of the three-electrode lithium-ion battery to the charging and discharging machine, set the rate, charge and discharge the three-electrode lithium-ion battery, and collect the charging cut-off voltage and discharging cut-off voltage of the positive and negative electrodes of the three-electrode battery. According to the charge and discharge curve of the button battery corresponding to this voltage, the gram capacity of the positive and negative electrodes at the corresponding voltage can be intercepted.

[0073] Test example

[0074] 20 positive and negative electrode sheets from the same batch were randomly selected and divided into two groups to measure the gram capacity of the positive and negative electrodes of the full-cell lithium-ion battery by the methods of Example 1 and Comparative Example 1, respectively. The results are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] Analyze Table 1:

[0079] The present application adopts a series connection method of buckling electricity. Compared with the three-electrode method, there is no obvious difference in the full charge and discharge positions of the positive and negative electrodes. Therefore, the gram capacity of the positive and negative electrodes calculated according to this voltage in the buckling curve is not much different, indicating that the method of the present application has the same accuracy as the three-electrode method.

[0080] Randomly take 5 batches of 100 positive plates and 100 negative plates, and characterize the gram capacity of the positive and negative electrodes of the full lithium-ion battery cell according to the method of this application, with a success rate of 95% (the remaining 5% of individual buckles fail due to abnormal polarization caused by assembly techniques, etc.); randomly take 5 batches of 100 positive plates and 100 negative plates, and characterize the gram capacity of the positive and negative electrodes of the full lithium-ion battery cell according to the three-electrode characterization method of comparative example 1, with a success rate of 60% (the remaining 40% have the following problems: three-electrode copper wire breakage; uneven or failed lithium plating of the copper wire; poor consistency and no valid data, etc.). It can be seen that the success rate of the method of this application is higher than that of the three-electrode characterization method.

[0081] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for characterizing the gram capacity of the positive and negative electrodes of a full-cell lithium-ion battery, including characterizing the charging gram capacity and the discharging gram capacity of the positive and negative electrodes of the full-cell lithium-ion battery, the characterization method comprising the following steps: S1, preparation before characterization: assemble the positive electrode sheet and the lithium sheet into a positive electrode simple battery cell, assemble the negative electrode sheet and the lithium sheet into a negative electrode simple battery cell, and assemble the positive electrode sheet and the negative electrode sheet into a full-cell simple battery cell; connect the negative electrode simple battery cell, the full-cell simple battery cell, and the positive electrode simple battery cell in series in sequence; S2, charge the series circuit in the full-cell charging mode, and end the charging after the full charge; record the charging capacity C0, the full-cell positive electrode charging capacity in grams = charging capacity C0 / weight of the positive electrode active material in the full-cell simple battery cell; the full-cell negative electrode charging capacity in grams = charging capacity C0 / weight of the negative electrode active material in the full-cell simple battery cell; S3, discharge the series circuit in the full-cell discharge mode, and end the discharge after full discharge; record the discharge capacity C1, the full-cell positive electrode discharge capacity in grams = discharge capacity C1 / the weight of the positive electrode active material in the full-cell simple battery cell; the full-cell negative electrode discharge capacity in grams = discharge capacity C1 / the weight of the negative electrode active material in the full-cell simple battery cell.

2. The characterization method according to claim 1, characterized in that: The simple battery cells include but are not limited to button cells, single-layer laminated cells and multi-layer laminated cells.

3. The characterization method according to claim 1, characterized in that: The negative electrode simple battery cell, the full battery cell simple battery cell, and the positive electrode simple battery cell are sequentially connected in series in the order of lithium sheet, negative electrode sheet, positive electrode sheet, negative electrode sheet, positive electrode sheet, and lithium sheet.

4. The characterization method according to claim 1, characterized in that: The full charge voltage of the full-cell simple battery cell is 3.5V-4.5V.

5. The characterization method according to claim 4, characterized in that: The charging process of the full-cell simple battery is 0.01-10C CC to 3.5-4.5V; CV to 0.05C.

6. The characterization method according to claim 1, characterized in that: The full discharge voltage of the full-cell simple battery is 2V-3V.

7. The characterization method according to claim 6, characterized in that: The discharge process of the full-cell simple battery is 0.01-10C DC to 2-3V.

8. The characterization method according to claim 1, characterized in that: After charging is completed, record the voltage V of the positive electrode simple battery cell 正 , the voltage of the negative electrode simple battery cell is V 负 , then V 正 It is the positive electrode potential of the full-cell simple battery after charging, V 负 It is the negative electrode potential of the full-cell simple battery after charging.

9. The characterization method according to claim 1, characterized in that: After the discharge is completed, record the voltage V' of the positive electrode simple battery cell 正 , the voltage of the negative electrode simple battery cell V' 负 , then V′ 正 It is the positive electrode potential of the simple battery cell with full battery, V' 负 That is the negative electrode potential of the full-cell simple battery.

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