A double-layer double-high electrode, a reserve lithium battery and a preparation method thereof

Abstract

This invention provides a double-layer, high-energy-density electrode, a storage lithium battery, and a method for preparing the same. The double-layer, high-energy-density electrode includes a current collector, a first active layer, and a second active layer. The first active layer is located between the current collector and the second active layer. The first active layer contains an energy-type active material, and the second active layer contains a pre-charged power-type active material. The open-circuit voltage difference between the energy-type active material and the pre-charged power-type active material is ≤0.5V. This invention provides a double-layer, high-energy-density electrode for storage lithium batteries with fast activation, high energy density, and good rate performance. It constructs an efficient conductive network, improving the battery's discharge performance. By controlling the porosity of the second material layer to be greater than that of the first material layer and by creating seepage drainage grooves on the surface of the second material layer, the electrolyte wetting rate of the electrode is increased, shortening the activation time.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a double-layer high-efficiency electrode, a lithium battery for storage, and a method for preparing the same. Background Technology

[0002] Reserve lithium batteries are batteries in which the dry-state cells and electrolyte are stored separately before discharge. During discharge, the dry-state cells come into contact with the electrolyte through an activation mechanism or external mechanical impact, resulting in an electrochemical reaction that supplies power. The dry-state cells remain in an inert environment during long-term storage, thus offering relatively superior safety and shelf life. Among reserve batteries, reserve lithium batteries have a higher energy density than water-activated batteries and thermal batteries, and are expected to serve as high-performance alternatives in specialized fields such as underwater equipment and fuses.

[0003] Besides energy density, activation time and rate performance are also key performance indicators for reserve batteries. Activation time refers to the time interval from the injection of electrolyte into the battery to the battery being able to start discharging under load. The shorter the activation time and the higher the discharge rate, the better the rapid response capability of the reserve battery, and the better it can meet the requirements of future new equipment.

[0004] Storage lithium batteries mainly include lithium thionyl chloride batteries, lithium vanadium pentoxide batteries, and lithium sulfur dioxide batteries, but these batteries cannot simultaneously meet the requirements of high energy density (≥200Wh / kg), high rate (≥5C), and fast activation (≤10s). Summary of the Invention

[0005] The purpose of this invention is to provide a double-layer, high-performance electrode, a storage lithium battery, and a method for preparing the same, in order to solve the problems in the prior art.

[0006] The technical solution of the present invention includes: a double-layer double-high type electrode, comprising: a current collector, a first active layer and a second active layer, wherein the first active layer is located between the current collector and the second active layer, the first active layer contains an energy-type active material, and the second active layer contains a pre-charged power-type active material, wherein the open-circuit voltage difference between the energy-type active material and the pre-charged power-type active material is ≤0.5V.

[0007] Specifically, the energy-type active materials include Cr2O5, Cr3O8, and Cr8O. 21 At least one of them.

[0008] Specifically, the pre-charged power-type active material is obtained by pre-charging a power-type active material with an initial state of charge of 0; the power-type active material with an initial state of charge of 0 includes LiCrO2, LiCoO2, LiNiO2, and LiNi a Cob Mn (1-a-b) O2 and LiNi a Co b Al (1-a-b) At least one of O2.

[0009] Specifically, the first material layer contains a first conductive agent, and the second material layer contains a second conductive agent, wherein the proportion of the first conductive agent in the first material layer is higher than the proportion of the second conductive agent in the second material layer.

[0010] Specifically, the porosity of the first material layer is less than that of the second material layer; the porosity of the first material layer is 25% to 40%, and the porosity of the second material layer is 35% to 45%.

[0011] Specifically, the first material layer contains a first binder, and the mass ratio of the energy-type active material, the first conductive agent and the first binder is (87-96):(2-6):(2-7).

[0012] Specifically, the second material layer contains a second binder, and the mass ratio of the pre-charged power active material, the second conductive agent and the second binder is (92-98):(1-4):(1-4).

[0013] Specifically, the surface of the second material layer facing away from the first material layer is provided with a plurality of seepage guiding grooves, the two ends of which extend to the side edge of the second material layer, and the total area of ​​the plurality of seepage guiding grooves accounts for 1% to 20% of the total area of ​​the second material layer.

[0014] The technical solution of the present invention also includes: a method for preparing a double-layer, double-high type electrode, comprising the steps of:

[0015] The power-type active material with an initial state of charge of 0 is mixed with a second conductive agent and then pre-charged to obtain a pre-charged power-type active material.

[0016] A first material layer slurry with a solid content of 40wt% to 60wt% is prepared using an energy-type active material, a first conductive agent and a first binder. The first material layer slurry is coated on the surface of the current collector and dried to obtain the first material layer.

[0017] A second material layer slurry with a solid content of 50wt% to 70wt% is prepared using a pre-charged power-type active material, a second conductive agent, and a second binder. The second material layer slurry is coated onto the surface of the first material layer, dried, and then compacted to obtain the second material layer.

[0018] On the surface of the second material layer, several permeation drainage grooves are constructed using laser etching to obtain a double-layer, double-high electrode.

[0019] The technical solution of the present invention also includes: a storage lithium battery, wherein the positive electrode adopts the double-layer double-high type electrode as described above.

[0020] The beneficial effects of this invention are as follows: It provides a double-layer, high-energy-density, and high-rate-performance electrode for reserve lithium batteries, which integrates high-energy-density energy-type active materials and high-rate-performance power-type active materials to improve the energy density and rate performance of the electrode. To prevent side reactions inside the electrode, the open-circuit voltage difference between the energy-type active material and the pre-charged power-type active material is controlled within 0.5V. By aligning the first material layer close to the current collector and adjusting the content of the first conductive agent in the first material layer, the electron transport efficiency of the first material layer is improved. By adjusting the proportion of the first conductive agent in the first material layer and the proportion of the second conductive agent in the second material layer, the different requirements of different cathode materials for the conductive network are met, thus constructing an efficient conductive network and improving the discharge performance of the battery. Taking into account the particle size differences of the active materials themselves and adjusting the content of the first and second conductive agents, the porosity of the first material layer is less than that of the second material layer after the electrode sheet is compacted. A seepage drainage groove is dug on the surface of the second material layer to improve the electrolyte wetting rate of the electrode while ensuring the energy density and rate performance of the electrode. Attached Figure Description

[0021] Figure 1 This is a longitudinal sectional view of an embodiment of the present invention;

[0022] Figure 2 This is a top view of Embodiment 1 of the present invention;

[0023] Figure 3 This is a top view of Embodiment 2 of the present invention.

[0024] In the picture:

[0025] 1. Current collector; 2. First material layer; 3. Second material layer; 4. Permeation drainage groove. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments and comparative examples only and are not intended to limit the scope of protection of this invention. It should be specifically noted that the same organic structure may have multiple names, and all such structures fall within the scope of this patent.

[0028] Unless otherwise defined, the raw materials, reagents, etc. used in the following examples can be purchased commercially or prepared according to reported methods.

[0029] The dual-layer, dual-high type electrode provided in this embodiment of the invention is mainly used in the field of lithium storage batteries. It contains two positive electrode material layers. Referring to the accompanying drawings, its structure includes a current collector 1, a first material layer 2, and a second material layer 3. The current collector is sheet-shaped, with a first material layer 2 disposed on both sides. The two separated sides of the two first material layers 2 are respectively disposed on the second material layer 3. The first material layer 2 contains an energy-type active material, a first conductive agent, and a first binder. The second material layer 3 contains a pre-charged power-type active material, a second conductive agent, and a second binder. By comprehensively utilizing the energy-type active material with high energy density and the power-type active material with good rate performance, the energy density and rate performance of the electrode are improved. Since the electron conductivity of the energy-type active material with high energy density is relatively poor, placing it in the first material layer 2 close to the current collector 1 can shorten the electron conduction distance and improve the electron transport efficiency of the electrode. However, since different types of active materials are selected in the first material layer 2 and the second material layer 3, in order to prevent side reactions inside the electrode, it should be ensured that the different active materials have similar electrode potentials or similar discharge voltage ranges. Therefore, when constructing a double-layer double-high type electrode, the open-circuit voltage between the energy-type active material and the pre-charged power-type active material should be ≤0.5V.

[0030] In implementation, energy-type active materials such as Cr2O5, Cr3O8, and Cr8O can be selected, which have high energy density. 21 One or more of the following can be selected: for power-type active materials, LiCrO2, LiCoO2, LiNiO2, and LiNi can be used, which have high rate capability. a Co b Mn (1-a-b) O2 and LiNi a Co b Al (1-a-b) One or more of O2, wherein the initial state of charge of chromium-based oxide is >0, and it can be directly discharged, while the initial state of charge of power active material is =0, and it cannot be directly discharged. Therefore, the power active material needs to be pre-charged to delithiate it to a state of charge >0.

[0031] When pre-charging the power-type active material, the pre-charging cutoff voltage of the power-type active material is controlled based on the open-circuit voltage difference between the energy-type active material and the pre-charged power-type active material being ≤0.5V, and the properties of the power-type active material itself. In this embodiment, the energy-type active material selected is a chromium-based oxide, whose open-circuit voltage is typically between 3.3 and 4.0V (relative to Li / Li). +However, power-type active materials experience slight losses after pre-charging. Therefore, a comprehensive comparison of specific material selections is necessary to control the pre-charging cutoff voltage of power-type active materials between 3.8 and 4.4V (relative to Li / Li). + The charging current is controlled between 0.01 and 0.2C.

[0032] Since energy-type active materials have high energy density but poor rate performance, while power-type active materials have low energy density but excellent rate performance, in order to improve the electron transport efficiency of the first material layer 2, construct an efficient conductive network, and improve the discharge performance of the battery, in this embodiment, the proportion of the first conductive agent in the first material layer 2 is higher than the proportion of the second conductive agent in the second material layer 3.

[0033] The first conductive agent and the second conductive agent are each selected from at least one of conductive carbon black, porous carbon and carbon nanotubes. The proportion of the first conductive agent in the first material layer 2 and the proportion of the second conductive agent in the second material layer 3 can be determined according to the specific selection of the first conductive agent and the second conductive agent.

[0034] Besides energy density and rate performance, activation time is also an important performance indicator for lithium-ion batteries. In the electrodes of lithium-ion batteries, the porosity of each material layer affects the electrolyte wetting rate, and thus the battery activation time. The higher the porosity, the faster the electrolyte wetting and the shorter the battery activation time. However, increased porosity is often accompanied by a decrease in the content of components in the material layer. The second material layer 3 is located on the outermost layer of the electrode and is the first part to contact the electrolyte during battery activation. The first material layer 2 is the main contributor to the electrode energy density. Considering the above factors, this embodiment controls the porosity of each material layer as follows: the porosity of the first material layer 2 is less than that of the second material layer 3. By designing a gradient of porosity in the electrode thickness direction, the electrolyte wetting rate is improved, the battery activation time is shortened, and the content of components in each material layer is not excessively sacrificed, especially the content of energy-type active materials and the first conductive agent in the first material layer 2.

[0035] In this embodiment, the particle size of the energy-type active material is smaller than that of the power-type active material. By controlling the content of the first and second conductive agents in each material layer, and considering the influence of the particle size of the energy-type and power-type active materials themselves, the first material layer 2 and the second material layer 3 have different porosities under the same compaction pressure. Preferably, the mass ratio of the energy-type active material, the first conductive agent, and the first binder in the first material layer 2 is (87-96):(2-6):(2-7), and the mass ratio of the pre-charged power-type active material, the second conductive agent, and the second binder in the second material layer 3 is (92-98):(1-4):(1-4). The first material layer 2 and the second material layer 3 are placed on the current collector 1 by a slurry coating method. After drying, the electrode is compacted, and the compaction density is controlled at 2.0-3.3 g / cm³. 3 The porosity of the first material layer 2 is 25% to 40%, and the porosity of the second material layer 3 is 35% to 45%.

[0036] In this embodiment, the first and second adhesives, as well as the solvent used in pulping, are all commonly used materials in the art and can be selected according to specific needs. For example, the first and second adhesives can be polyvinylidene fluoride, and the solvent can be N-methylpyrrolidone. During implementation, adjustments can be made according to specific needs. To improve the bonding force between the material layer and the current collector 1, the proportion of the first adhesive in the first material layer 2 can be appropriately increased.

[0037] To further improve the electrolyte wetting rate of the electrode and shorten the battery activation time, this embodiment provides a plurality of seepage-guiding grooves 4 on the outer surface of the second material layer 3, i.e., the surface opposite to the first material layer 2. The seepage-guiding grooves 4 extend laterally, longitudinally, or obliquely, with both ends extending to the side edge of the second material layer 3. The seepage-guiding grooves 4 enhance the electrode's rapid electrolyte absorption capacity. Considering both the electrode activation time and structural strength, in this embodiment, the width of the seepage-guiding grooves 4 is controlled between 0.1 and 2 mm, and the depth is controlled between 5 and 40 μm. The distribution density of the seepage-guiding grooves 4 can be configured according to actual needs, but the total area of ​​the plurality of seepage-guiding grooves 4 should be controlled to account for 1% to 20% of the total area of ​​the second material layer 3.

[0038] This embodiment also provides a method for preparing the above-mentioned double-layer double-high type electrode, including the following steps:

[0039] (1) The power-type active material with an initial state of charge of 0 is mixed with the second conductive agent and then pre-charged to obtain the pre-charged power-type active material.

[0040] In this step, the specific pre-charging method is as follows: The power-type active material with an initial state of charge of 0 is mixed with a second conductive agent. After adding an appropriate amount of electrolyte, the mixture is stirred at 3000 rpm to obtain a paste-like positive electrode slurry. The paste-like positive electrode slurry is poured into an insulating charging device, and an aluminum current collector is inserted. A polyolefin membrane with a thickness of 24 μm is covered on the surface of the paste-like positive electrode slurry. The membrane size should be larger than the inner cavity of the charging device to prevent the paste-like positive electrode slurry from overflowing from below the membrane. An appropriate amount of electrolyte is added to the top of the membrane, and a lithium metal sheet containing the current collector is placed as the negative electrode. The charging device is then covered with a cover plate to ensure internal sealing. Pre-charging is performed using a charging and discharging device. The pre-charging current and charging cut-off voltage are determined based on the specific selection of the power-type and energy-type active materials. After charging is complete, the device is disassembled, the positive electrode material paste is removed, cleaned with DMC, and then dried in a 40°C oven for 5 hours.

[0041] (2) A first material layer slurry with a solid content of 40wt% to 60wt% is prepared by using an energy-type active material, a first conductive agent and a first binder. The first material layer slurry is coated on the surface of the current collector and dried to obtain the first material layer.

[0042] In this step, the coating amount of the first material layer slurry is controlled between 5 and 30 mg / cm². 2 .

[0043] (3) A second material layer slurry with a solid content of 50wt% to 70wt% is prepared by using a pre-charged power-type active material, a second conductive agent and a second binder. The second material layer slurry is coated on the surface of the first material layer, dried and compacted to obtain the second material layer.

[0044] In this step, the coating amount of the second material layer slurry is controlled between 5 and 30 mg / cm². 2 The compacted density is 2.0–3.3 g / cm³. 3 .

[0045] (4) On the surface of the second material layer, several permeation drainage grooves are constructed by laser etching to obtain a double-layer double-high electrode.

[0046] In this step, during laser etching, the laser power is 2W to 30W, the wavelength is 200nm to 1um, the frequency is 10 to 50kHz, and the etching speed is 200 to 5000mm / s.

[0047] This embodiment also provides a reserve lithium battery. The positive electrode of the reserve lithium battery adopts the above-mentioned double-layer double-high type electrode, while the negative electrode, electrolyte and assembly method are no different from those of conventional reserve lithium batteries.

[0048] The following are specific embodiments of the present invention.

[0049] Example 1

[0050] Fabrication of bilayer double-high type electrode

[0051] (1) Weigh LiCoO2, conductive carbon black and carbon nanotubes in a mass ratio of 96:1.5:0.5, add an appropriate amount of electrolyte, and stir the above substances at 3000 rpm to obtain a paste-like positive electrode slurry; pour the paste-like positive electrode slurry into an insulating charging device, insert an aluminum current collector, cover the surface of the paste-like positive electrode slurry with a polyolefin membrane with a thickness of 24 μm, and the membrane size should be larger than the inner cavity of the charging device so that the paste-like positive electrode slurry will not overflow from below the membrane; add an appropriate amount of electrolyte to the top of the membrane, place a lithium metal sheet containing the current collector as the negative electrode, and cover the charging device with a cover plate to ensure internal sealing; use a charging and discharging device for pre-charging, with a pre-charging current of 0.01C and a charging cut-off voltage of 4.0V; after charging is completed, disassemble the device and take out the positive electrode material paste, clean it with DMC, and dry it in a 40℃ oven for 5 hours.

[0052] (2) Weigh Cr8O according to the mass ratio of 87:5.5:0.5:7. 21 Conductive carbon black, carbon nanotubes, and polyvinylidene fluoride were mixed with an appropriate amount of NMP and transferred to a homogenizer slurry tank. The mixture was stirred at low speed (45 rpm) and high speed (3000 rpm) for 4 hours. Then, NMP was added to adjust the slurry solid content to 50%, and the mixture was dispersed at low speed (45 rpm) and high speed (3000 rpm) for 2 hours. The entire homogenization process was carried out under a vacuum of -0.08 MPa to -0.05 MPa. The final material layer slurry was obtained.

[0053] (3) Weigh the mixture obtained after pre-charging in step (1) and polyvinylidene fluoride at a mass ratio of 98:2. Add an appropriate amount of NMP and transfer it to the slurry tank of a homogenizer. Mix at low speed (45 rpm) and high speed (3000 rpm) for 4 hours. Add NMP to adjust the solid content of the slurry to 65%. Disperse at low speed (45 rpm) and high speed (3000 rpm) for 2 hours. Maintain a vacuum of -0.08 MPa to -0.05 MPa throughout the homogenization process. The second material layer slurry is finally obtained.

[0054] (4) Using aluminum foil of material 1100 and thickness 0.012mm as the current collector, a transfer coating method is used with a coating speed of 2000mm / min and an oven temperature of 100~140℃. The first material layer slurry is coated on both sides of the current collector with a coating amount of 20mg / cm². 2 .

[0055] (5) The second material layer slurry is coated onto the surface of the first material layer at a coating speed of 2000 mm / min, the oven temperature is set to 100–140℃, and the coating amount is 10 mg / cm³. 2 .

[0056] (6) The electrode sheet obtained in step (5) is compacted to a density of 3.0 g / cm³. 3 .

[0057] (7) Laser etching is performed on the outermost second material layer on both sides of the electrode obtained in step (6) to form drainage grooves. The etching scheme is as follows: several drainage grooves extending across the entire electrode width direction, with a width of 1 mm and a depth of 20 μm. The total area of ​​the drainage grooves accounts for 5% of the total area of ​​the electrode. The laser power is 30 W, the wavelength is 1 μm, and the etching speed is 500 mm / s. The final result is an attached... Figure 2 The double-layer, double-high type electrode is shown.

[0058] The double-layer, high-efficiency electrode prepared in this embodiment was stacked with lithium metal and a 16μm polyolefin separator to form an 80Ah dry-state cell, which was then encapsulated in a square aluminum casing to form a storage lithium battery. An activation discharge test was conducted on the battery. Timing began simultaneously with electrolyte injection. Discharge at 1C began 10 seconds after injection, and the battery discharge voltage exceeded 2.5V, demonstrating its ability to discharge externally. The final battery discharge specific energy reached 380Wh / kg (excluding the activation system and electrolyte).

[0059] Example 2

[0060] Fabrication of bilayer double-high type electrode

[0061] (1) Weigh LiNi according to a mass ratio of 95:1.5:0.5 0.8 Co 0.1 Mn 0.1 O2, conductive carbon black, and carbon nanotubes are mixed with an appropriate amount of electrolyte and stirred at 3000 rpm to obtain a paste-like positive electrode slurry. The paste-like positive electrode slurry is poured into an insulating charging device, and an aluminum current collector is inserted. A polyolefin membrane with a thickness of 24 μm is then placed on the surface of the paste-like positive electrode slurry. The membrane size should be larger than the inner cavity of the charging device to prevent the paste-like positive electrode slurry from overflowing from below the membrane. An appropriate amount of electrolyte is added to the top of the membrane, and a lithium metal sheet containing the current collector is placed as the negative electrode. The charging device is then covered with a cover plate to ensure internal sealing. Pre-charging is performed using a charging and discharging device with a pre-charging current of 0.01C and a charging cut-off voltage of 4.2V. After charging, the device is disassembled, the positive electrode material paste is removed, cleaned with DMC, and then dried in a 40℃ oven for 5 hours.

[0062] (2) Weigh Cr2O5, conductive carbon black, carbon nanotubes, and polyvinylidene fluoride according to a mass ratio of 89:4:1:6. Add an appropriate amount of NMP and transfer to a homogenizer slurry tank. Mix at low speed (45 rpm) and high speed (3000 rpm) for 4 hours. Add NMP to adjust the slurry solid content to 60%. Disperse at low speed (45 rpm) and high speed (3000 rpm) for 2 hours. Maintain a vacuum of -0.08 MPa to -0.05 MPa throughout the homogenization process. The first material layer slurry is finally obtained.

[0063] (3) Weigh the mixture obtained after pre-charging in step (1) and polyvinylidene fluoride at a mass ratio of 98:2. Add an appropriate amount of NMP and transfer it to the slurry tank of a homogenizer. Mix at low speed (45 rpm) and high speed (3000 rpm) for 4 hours. Add NMP to adjust the solid content of the slurry to 65%. Disperse at low speed (45 rpm) and high speed (3000 rpm) for 2 hours. Maintain a vacuum of -0.08 MPa to -0.05 MPa throughout the homogenization process. The second material layer slurry is finally obtained.

[0064] (4) Using aluminum foil of material 1100 and thickness 0.012mm as the current collector, a transfer coating method is used with a coating speed of 2000mm / min and an oven temperature of 100~140℃. The first material layer slurry is coated on both sides of the current collector with a coating amount of 5mg / cm². 2 .

[0065] (5) The second material layer slurry is coated onto the surface of the first material layer at a coating speed of 2000 mm / min, the oven temperature is set to 100–140℃, and the coating amount is 30 mg / cm³. 2 .

[0066] (6) The electrode sheet obtained in step (5) is compacted to a density of 3.15 g / cm³. 3 .

[0067] (7) Laser etching is performed on the outermost second material layer on both sides of the electrode obtained in step (6) to form seepage drainage grooves. The etching scheme is as follows: several through-type oblique seepage drainage grooves are formed throughout the entire electrode. The width of the seepage drainage grooves is 1 mm, the depth is 15 μm, and the total area of ​​the several seepage drainage grooves accounts for 5% of the total area of ​​the electrode. The laser power is 30 W, the wavelength is 1 μm, and the etching speed is 700 mm / s. Finally, the attached electrode is obtained. Figure 3 The double-layer, double-high type electrode is shown.

[0068] The double-layer, high-efficiency electrode prepared in this embodiment was stacked with lithium metal and a 14μm polyolefin separator to form an 80Ah dry-state cell, which was then encapsulated in a square aluminum casing to form a storage lithium battery. An activation discharge test was conducted on the battery. Timing began simultaneously with electrolyte injection. Discharge at 5C began 10 seconds after injection and continued for 30 seconds at 5C. Throughout the discharge process, the battery discharge voltage exceeded 2.5V, demonstrating its ability to discharge externally. The continuous 5C discharge time reached 600 seconds, and the final battery discharge specific energy reached 330Wh / kg (excluding the activation system and electrolyte).

[0069] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A double-layer double-height electrode, characterized by The electrode comprises: a current collector, a first material layer and a second material layer, the first material layer is between the current collector and the second material layer, the first material layer contains energy-type active material, the second material layer contains pre-charged power-type active material, the open circuit voltage difference between the energy-type active material and the pre-charged power-type active material is less than or equal to 0.5V; The energy-type active material includes at least one of Cr2O5, Cr3O8, and Cr8O 21 ​ The pre-charged power-type active material is obtained by pre-charging a power-type active material with an initial state of charge = 0; the power-type active material with an initial state of charge = 0 includes at least one of LiCrO2, LiCoO2, LiNiO2, LiNi a Co b Mn (1-a-b) O2and LiNi a Co b Al (1-a-b) O2.

2. The double-layer double-high electrode according to claim 1, characterized by the first material layer contains a first conductive agent, the second material layer contains a second conductive agent, the proportion of the first conductive agent in the first material layer is higher than the proportion of the second conductive agent in the second material layer.

3. The double-layer double-high electrode according to claim 2, characterized by The porosity of the first material layer is less than the porosity of the second material layer; the porosity of the first material layer is 25% to 40%, and the porosity of the second material layer is 35% to 45%.

4. The double-layer double-high electrode according to claim 3, characterized by The first material layer contains a first binder, and the mass ratio of the energy-type active material, the first conductive agent and the first binder is (87-96):(2-6):(2-7).

5. The dual-layer dual-height electrode of claim 3, wherein, The second material layer contains a second binder, and the mass ratio of the pre-charged power-type active material, the second conductive agent and the second binder is (92-98):(1-4):(1-4).

6. The double-layer double-high electrode according to any one of claims 2 to 5, characterized in that, The surface of the second material layer away from the first material layer is provided with a plurality of liquid permeation and flow guide grooves, the two ends of the liquid permeation and flow guide grooves respectively extend to the side edges of the second material layer, and the total area of the plurality of liquid permeation and flow guide grooves accounts for 1% to 20% of the total area of the second material layer.

7. The method of making a double-dual-height electrode according to any one of claims 1-6, wherein, The method comprises the steps of: mixing power-type active material with an initial state of charge of 0 and a second conductive agent to pre-charge, to obtain pre-charged power-type active material; using energy-type active material, a first conductive agent and a first binder to prepare a first material layer slurry with a solid content of 40wt% to 60wt%, coating the first material layer slurry on the surface of the current collector, drying to obtain the first material layer; using pre-charged power-type active material, a second conductive agent and a second binder to prepare a second material layer slurry with a solid content of 50wt% to 70wt%, coating the second material layer slurry on the surface of the first material layer, drying and then compacting to obtain the second material layer; using a laser etching method to construct a plurality of liquid permeation and flow guide grooves on the surface of the second material layer to obtain a double-layer double-high electrode.

8. A reserve lithium battery characterized by comprising: The positive electrode of the reserve lithium battery is the double-layer double-high electrode according to any one of claims 1-6.

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