Bipolar electrode plate and preparation method thereof, battery, battery pack and electric equipment

Abstract

The invention provides a bipolar electrode plate and a preparation method thereof, a battery, a battery pack and electric equipment. The bipolar electrode plate comprises an electrode current collector, a first coating located on the surface of one side of the electrode current collector, and a second coating located on the surface of the other side of the electrode current collector, the first coating layer and the second coating layer each independently include a sodium-containing electrode active material. The performance such as energy density of the battery can be improved.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a bipolar electrode sheet and a preparation method thereof, a battery, a battery pack and an electrical device. Background Art

[0002] Bipolar batteries are usually composed of multiple bipolar electrode sheets stacked in series. The bipolar electrode sheets are mainly formed by coating active materials of different polarities on two opposite sides of a bipolar current collector (one side is coated with a positive electrode active material, and the other side is coated with a negative electrode active material). However, due to factors such as the structure and material composition of the bipolar electrode sheets, existing bipolar batteries generally have problems such as low energy density, which need to be solved urgently. Summary of the invention

[0003] The present invention provides a bipolar electrode sheet and a preparation method thereof, a battery, a battery pack and an electrical device, so as to at least solve the problem of low energy density of bipolar batteries existing in the prior art.

[0004] In one aspect of the present invention, a bipolar electrode sheet is provided, comprising an electrode current collector, a first coating located on one side surface of the electrode current collector, and a second coating located on the other side surface of the electrode current collector; the first coating and the second coating each independently comprise a sodium-containing electrode active material.

[0005] According to one embodiment of the present invention, the sodium-containing electrode active material in the first coating layer is the same as the sodium-containing electrode active material in the second coating layer.

[0006] According to one embodiment of the present invention, the sodium-containing electrode active material includes sodium-containing phosphate.

[0007] According to one embodiment of the present invention, the sodium phosphate comprises Na 3 V 2 (PO 4 ) 3 、NaVPO 4 F. Na 3 V 2 (PO 4 ) 2 F 3 One or more of .

[0008] According to one embodiment of the present invention, the electrode current collector comprises aluminum foil.

[0009] According to one embodiment of the present invention, the ratio of the surface density of the first coating layer to the surface density of the second coating layer is 0.8-1.2.

[0010] According to one embodiment of the present invention, the surface density of the first coating is 100 to 250 g / m 2 The surface density of the second coating is 80 to 300 g / m 2 .

[0011] Another aspect of the present invention provides a method for preparing a bipolar electrode sheet, comprising: using a first slurry to form a first coating on one side surface of the electrode current collector, and using a second slurry to form a second coating on the other side surface of the electrode current collector by a coating method, to obtain the bipolar electrode sheet; wherein the first slurry contains the sodium-containing electrode active material and an organic solvent, and the second slurry contains the sodium-containing electrode active material and an organic solvent.

[0012] According to one embodiment of the present invention, the organic solvent in the first slurry is the same as the organic solvent in the second slurry.

[0013] According to one embodiment of the present invention, the organic solvent in the first slurry includes N-methylpyrrolidone; and / or the organic solvent in the second slurry includes N-methylpyrrolidone.

[0014] Another aspect of the present invention provides a battery, comprising the bipolar electrode sheet or a bipolar electrode sheet prepared according to the method for preparing the bipolar electrode sheet.

[0015] According to one embodiment of the present invention, it also includes a first single-sided pole piece and a second single-sided pole piece, and the bipolar electrode sheet is located between the first single-sided pole piece and the second single-sided pole piece; the first single-sided pole piece includes the electrode collector and the first coating located on the side of the electrode collector facing the bipolar electrode sheet; the second single-sided pole piece includes the electrode collector and the second coating located on the side of the electrode collector facing the bipolar electrode sheet; the first coating in the bipolar electrode sheet faces the second single-sided pole piece, and the second coating faces the first single-sided pole piece.

[0016] According to one embodiment of the present invention, the first single-sided pole piece includes a first pole lug connected to the electrode current collector of the first single-sided pole piece, and the second single-sided pole piece includes a second pole lug connected to the electrode current collector of the second single-sided pole piece.

[0017] Another aspect of the present invention provides a battery pack comprising the above-mentioned battery.

[0018] Another aspect of the present invention provides an electrical device comprising the above-mentioned battery or the above-mentioned battery pack.

[0019] The present invention provides a bipolar electrode sheet and a preparation method thereof, a battery pack and an electrical device. In the bipolar electrode sheet, a first coating is provided on one side surface of an electrode current collector and a second coating is provided on the other side surface. The first coating and the second coating respectively include sodium-containing electrode active materials, that is, the first coating and the second coating have the same type of electrode active materials, which can improve the energy density and energy performance of the bipolar battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the pole core structure according to an embodiment of the present invention.

[0021] Explanation of the reference numerals: 1: first coating layer; 2: second coating layer; 3: electrode current collector; 4: diaphragm; 5: packaging component; 11: first pole ear; 12: second pole ear; 100: bipolar electrode sheet; 101: first single-sided pole sheet; 102: second single-sided pole sheet. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0023] In the related technology, due to factors such as the structure and material composition of the bipolar electrode sheets, existing bipolar batteries generally have problems such as low energy density, which need to be solved urgently.

[0024] Specifically, the bipolar current collector in the bipolar electrode sheet is usually a metal foil such as copper foil or aluminum foil. For lithium-ion batteries, these metal foils are difficult to be compatible with positive and negative electrode materials (such as lithium iron phosphate and graphite, etc.) during the charge and discharge process of the battery. For example, aluminum foil can form an alloy with lithium at the negative electrode reaction potential, and copper foil is easily oxidized at the high positive electrode potential. Compared with lithium-ion batteries, sodium-ion batteries can circumvent the above problems to a certain extent. For example, aluminum foil will not alloy with sodium and can be used as the positive electrode foil (positive electrode current collector) and negative electrode foil (negative electrode current collector) of sodium-ion batteries. Therefore, the development of bipolar sodium-ion batteries has gradually received widespread attention and application.

[0025] However, in bipolar sodium-ion batteries, different types of active materials are usually coated on the positive and negative sides of the current collector to form a positive electrode coating and a negative electrode coating, respectively. The positive electrode active material (positive electrode active substance) in the positive electrode coating is usually a sodium-containing active material, and the negative electrode active material in the negative electrode coating is a negative electrode active substance such as hard carbon and graphite. On the one hand, during the charge and discharge cycle of bipolar batteries, the solid electrolyte film (SEI film) formed on the electrode surface and other side reactions are serious, resulting in the loss of sodium ions, which makes the discharge capacity of the bipolar battery low and affects the battery's energy density and other performance. On the other hand, in the preparation process of bipolar electrode sheets, there is also the problem of incompatibility between the formation process of the positive electrode coating and the negative electrode coating, which will also affect the battery performance. For example: (1) In the preparation process of bipolar electrode sheets, when different types of active materials are coated on the opposite sides of the current collector, the coatings on both sides will affect each other. Specifically, the positive electrode coating containing sodium-containing positive electrode active materials is coated with an oil-based (organic solvent system) positive electrode slurry, while the negative electrode coating containing negative electrode active materials such as hard carbon and graphite is coated with an aqueous negative electrode slurry. During the drying process after coating, the oil-based positive electrode on the positive electrode side The atmosphere generated by the slurry (organic solvent) and the atmosphere generated by the aqueous negative electrode slurry on the negative electrode side (water) affect the positive and negative electrode materials respectively (for example, the coating of the aqueous negative electrode slurry will affect the state of the positive electrode side), thereby affecting the performance of the bipolar electrode sheet obtained; (2) During the drying process after coating, the expansion and contraction conditions are different due to factors such as the difference in solvent and drying rate of the coating on both sides. At the same time, different types of active materials on both sides usually have different mechanical properties. For example, the rolling force and elongation are different, which can easily cause the electrode sheet to bend. In order to reduce the degree of bending of the electrode sheet, the rolling pressure during rolling is usually reduced to reduce the compaction density; (3) It is difficult to take into account the compaction density of the positive electrode coating and the negative electrode coating in the rolling process after drying. For example, when the positive electrode coating reaches the target compaction density, the negative electrode coating cannot meet the standard, which will also affect the performance of the bipolar electrode sheet.

[0026] The embodiment of the present invention provides a bipolar electrode sheet 100, such as Figure 1 As shown, the bipolar electrode sheet 100 includes an electrode current collector 3, a first coating 1 located on one side of the electrode current collector 3, and a second coating 2 located on the other side of the electrode current collector 3; the first coating 1 and the second coating 2 each independently include a sodium-containing electrode active material.

[0027] In the above-mentioned bipolar electrode sheet 100 system, the first coating 1 and the second coating 2 located on opposite sides of the electrode current collector 3 have the same type of electrode active materials, which can effectively improve the energy density and energy performance of the bipolar battery.

[0028] According to the research of the inventor of the present application, in the above-mentioned bipolar electrode sheet, the first coating layer and the second coating layer located on opposite sides of the electrode current collector both include sodium-containing electrode active materials, that is, the first coating layer and the second coating layer have the same type of electrode active materials, which is conducive to the first coating layer and the second coating layer being formed by coating with the same system of slurry, and specifically by coating with oil-based slurry, which can avoid the adverse effects of the atmosphere generated by different system slurries (such as water-based slurry on one side and oil-based slurry on the first coating layer and the second coating layer) during the formation of the first coating layer and the second coating layer, and at the same time, it is also conducive to the first coating layer and the second coating layer reaching the target compaction density through rolling and other processes during the preparation of the electrode sheet, which can avoid the problem that the compaction density of the coating layers on both sides cannot be taken into account in the rolling process during the preparation of the electrode sheet due to the use of different types of electrode active materials. Therefore, in the embodiment of the present invention, the coating and formation of the first coating layer and the second coating layer are facilitated, thereby facilitating the preparation of the bipolar electrode sheet, and further ensuring the energy density and other properties of the electrode sheet, solving the processing process problem of the bipolar electrode sheet.

[0029] In addition, in the bipolar electrode sheet of the embodiment of the present invention, the electrode current collector is used as a spacer between the positive and negative electrodes (i.e., the first coating and the second coating), and electrons are transferred between the positive and negative electrode materials through the electrode current collector, which can reduce the ohmic impedance of current transfer and simplify the series structure of the bipolar battery. The series connection of battery cells is achieved by simplifying the structure (electrode current collector), avoiding complex series components, which is beneficial to the high specific capacity and specific energy output and other performance of the bipolar battery, and can reduce the weight of the battery and reduce costs.

[0030] In an embodiment of the present invention, the first coating 1 and the second coating 2 can be formed by coating with a slurry of the same system, specifically, by coating with an oil-based slurry. This can avoid the adverse effects of the atmosphere generated by the slurries of different systems (such as water-based slurry on one side and oil-based slurry on the first coating 1 and the second coating 2) during the formation of the first coating 1 and the second coating 2. At the same time, it is also beneficial for the first coating 1 and the second coating 2 to reach the target compaction density through processes such as rolling during the preparation of the electrode sheet. This can avoid the problem of not being able to take into account the compaction density of the coatings on both sides in the rolling process during the preparation of the electrode sheet due to the use of different types of electrode active materials. It is also compatible with existing battery production lines without the need to additionally set up a coating process production line on the negative electrode side, which is beneficial to actual industrial production.

[0031] The bipolar electrode sheet 100 of the embodiment of the present invention is a bipolar sodium ion electrode sheet applied to a bipolar sodium ion battery. The first coating 1 and the second coating 2 are equivalent to coatings of different polarities, for example, the first coating 1 is used as a positive electrode coating, and the second coating 2 is used as a negative electrode coating. During the charge and discharge process of the battery, the sodium ions provided by the sodium-containing electrode active material serve as active ions, that is, the sodium ions are deintercalated between the positive and negative electrodes to realize the charge and discharge process of the battery.

[0032] Specifically, the sodium-containing electrode active material may include sodium-containing phosphate, that is, the sodium-containing electrode active material in the first coating layer 1 may include sodium-containing phosphate, and the sodium-containing electrode material in the second coating layer 2 may include sodium-containing phosphate.

[0033] In some embodiments, the sodium-containing phosphate may include sodium vanadium phosphate (Na 3 V 2 (PO 4 ) 3 ), NaVPO 4 F. Na 3 V 2 (PO 4 ) 2 F 3 One or more of, that is, the sodium phosphate in the first coating 1 may include Na 3 V 2 (PO 4 ) 3 、NaVPO 4 F. Na 3 V 2 (PO 4 ) 2 F 3 One or more of the above, the sodium phosphate in the second coating 2 may include Na 3 V 2 (PO 4 ) 3 、NaVPO 4 F. Na 3 V 2 (PO 4 ) 2 F 3 One or more of .

[0034] According to the inventor's research, the above Na 3 V 2 (PO 4 ) 3 、NaVPO 4 F. Na 3 V 2 (PO 4 ) 2 F3 Sodium-containing phosphates can be used as positive electrode active materials (sodium-containing electrode active materials in the positive electrode coating) or negative electrode active materials (sodium-containing electrode active materials in the negative electrode coating), which is beneficial to the electrochemical performance of the bipolar electrode sheet 100. At the same time, sodium-containing phosphates have higher safety. The use of sodium-containing phosphate-based electrode active materials with higher safety can improve the safety of bipolar batteries while increasing the energy density and energy of bipolar batteries.

[0035] After further investigation, it is found that the sodium-containing electrode active material in the first coating 1 is the same as the sodium-containing electrode active material in the second coating 2. For example, the sodium-containing electrode active material in the first coating 1 and the sodium-containing electrode material in the second coating 2 are both Na 3 V 2 (PO 4 ) 3 In this way, the sodium-containing electrode active material in the first coating 1 is the same as the sodium-containing electrode active material in the second coating 2, forming a bipolar electrode sheet 100 with the same electrode active material on opposite sides of the electrode current collector 3, which is beneficial to further improve the energy density and energy performance of the bipolar battery.

[0036] In addition, the above-mentioned electrode current collector 3 may include aluminum foil, which has good stability in the sodium ion battery system, for example, it will not alloy with sodium. At the same time, aluminum foil is used as the electrode current collector, and electrons are transferred between the positive and negative electrode materials through the aluminum foil current collector, which has the advantages of small current transfer impedance, thereby improving the electrochemical performance of the bipolar battery.

[0037] In addition, the ratio of the surface density of the first coating 1 to the surface density of the second coating 2 can be 0.8-1.2, for example, 0.8, 0.9, 1, 1.1, 1.2 or a range composed of any two of them, which is conducive to further improving the energy density and energy performance of the bipolar battery. The reason for the analysis is that by controlling the ratio of the surface density of the first coating 1 and the second coating 2 within the above range, reducing the surface density difference between the first coating 1 and the second coating 2, the difference in their ductility can be further reduced, and the problem of electrode sheet bending caused by different ductility can be alleviated (generally, the greater the difference in surface density between the first coating 1 and the second coating 2, the greater the degree of bending of the electrode sheet), thereby maintaining a more suitable rolling pressure, increasing the compaction density of the first coating 1 and the second coating 2, and improving the energy density and energy performance of the bipolar battery.

[0038] Specifically, the surface density of the first coating layer 1 may be greater than, equal to, or less than the surface density of the second coating layer 2 .

[0039] In some embodiments, the surface density of the first coating 1 may be 150 to 250 g / m 2 , for example 150g / m2 , 160g / m 2 , 170g / m 2 , 180g / m 2 , 190g / m 2 , 200g / m 2 , 210g / m 2 , 220g / m 2 , 230g / m 2 , 240g / m 2 , 250g / m 2 Or a range consisting of any two of them.

[0040] In some embodiments, the surface density of the second coating 2 may be 80 to 300 g / m 2 , for example 80g / m 2 , 100g / m 2 , 120g / m 2 , 140g / m 2 , 160g / m 2 , 180g / m 2 , 200g / m 2 , 220g / m 2 , 240g / m 2 , 260g / m 2 , 280g / m 2 , 300g / m 2 Or a range consisting of any two of them.

[0041] In an embodiment of the present invention, the amount of auxiliary materials on the surfaces of the opposite sides of the electrode current collector 3 (i.e., the mass, thickness, surface density and other characteristics of the first coating 1 and the second coating 2) can be flexibly controlled based on actual needs (for example, according to the specific capacity of the positive and negative electrode active materials, the proportion of active materials, the N / P ratio and other design conditions), thereby also having the advantages of good flexibility and a wide range of applications.

[0042] In addition, the first coating 1 may further include a conductive agent and a binder. Based on the total mass of the first coating 1, the mass fraction of the sodium-containing electrode active material in the first coating 1 (i.e., the proportion of the mass of the sodium-containing electrode active material to the total mass of the first coating 1) may be 90 to 98%, the mass fraction of the conductive agent in the first coating 1 may be 1 to 5%, and the mass fraction of the binder in the first coating 1 may be 1 to 5%.

[0043] In addition, the second coating 2 may also include a conductive agent and a binder. Based on the total mass of the second coating 2, the mass fraction of the sodium-containing electrode active material in the second coating 2 (i.e., the proportion of the mass of the sodium-containing electrode active material to the total mass of the second coating 2) may be 90 to 98%, the mass fraction of the conductive agent in the second coating 2 may be 1 to 5%, and the mass fraction of the binder in the second coating 2 may be 1 to 5%.

[0044] In an embodiment of the present invention, the conductive agent in the first coating 1 and the second coating 2 can be a conventional conductive material in the art. For example, the conductive agent in the first coating 1 can include one or more conductive materials such as graphene, carbon nanotubes (CNT), acetylene black (CB), etc., and the conductive agent in the second coating 2 can include one or more conductive materials such as graphene, carbon nanotubes, acetylene black, etc.

[0045] In the embodiment of the present invention, the binder in the first coating 1 and the second coating 2 may be a conventional binder material in the art, for example, a commonly used binder for lithium batteries or sodium batteries in the art. For example, the binder in the first coating 1 may include polyvinylidene fluoride (PVDF), and the binder in the second coating 2 may include polyvinylidene fluoride (PVDF). The binder such as PVDF used can be obtained by conventional methods in the art, for example, commercially available, and illustratively, PVDF includes one or more of PVDF5130, PVDF2600, etc.

[0046] An embodiment of the present invention also provides a method for preparing the above-mentioned bipolar electrode sheet 100, comprising: using a coating method, using a first slurry to form a first coating 1 on one side surface of an electrode collector 3, and using a second slurry to form a second coating 2 on the other side surface of the electrode collector 3, to obtain the bipolar electrode sheet 100; wherein the first slurry contains a sodium-containing electrode active material and an organic solvent, and the second slurry contains a sodium-containing electrode active material and an organic solvent.

[0047] In the above preparation process, the electrode active materials in the first slurry and the second slurry are the same type of electrode active materials (i.e., both are sodium-containing electrode active materials), and the first slurry and the second slurry are both oil-based slurries (i.e., the solvents therein are both organic solvents). In this way, the first coating 1 and the second coating 2 are formed by coating with the oil-based slurry, respectively, and the adverse effects of the atmosphere generated by the different system slurries (e.g., one side is water-based slurry and the other side is oil-based slurry) on the first coating 1 and the second coating 2 during the formation of the first coating 1 and the second coating 2 can be avoided (for example, avoiding affecting the state of the positive electrode coating when coating the water-based negative electrode slurry).

[0048] In some embodiments, the organic solvent in the first slurry may include N-methylpyrrolidone (NMP).

[0049] In some embodiments, the organic solvent in the second slurry may include N-methylpyrrolidone (NMP).

[0050] Specifically, the organic solvent in the first slurry and the organic solvent in the second slurry can be the same, for example, the organic solvent in the first slurry and the organic solvent in the second slurry are both NMP, which is beneficial to the coating and baking of the electrode and improves the preparation efficiency of the electrode.

[0051] In a specific implementation, the components for forming the first coating 1, such as sodium-containing electrode active materials, conductive agents and binders, can be dispersed in an organic solvent (such as NMP) to prepare a uniform first slurry, and the components for forming the second coating 2, such as sodium-containing electrode active materials, conductive agents and binders, can be dispersed in an organic solvent (such as NMP) to prepare a uniform second slurry; the first slurry is then applied to one side surface of the electrode collector 3, and the second slurry is applied to the other side surface of the electrode collector 3. After drying (or baking, baking) and rolling processes, the first coating 1 is formed on one side surface of the electrode collector 3, and the second coating 2 is formed on the other side surface of the electrode collector 3, respectively, to obtain a bipolar electrode sheet 100.

[0052] Specifically, the first slurry and the second slurry can be the same, that is, the organic solvent in the first slurry, and the types and contents of components such as the sodium-containing electrode active material are substantially the same. In specific implementation, the components used to form the first coating 1, such as the sodium-containing electrode active material, the conductive agent and the binder, can be dispersed in an organic solvent (such as NMP) to prepare a slurry; a portion of the slurry is taken as the first slurry, and it is applied to one side of the electrode current collector 3 to form the first coating 1, and another portion of the slurry is taken as the second slurry, and it is applied to the other side of the electrode current collector 3 to form the second coating 2.

[0053] In the embodiment of the present invention, the electrode active materials in the first slurry and the second slurry are the same type of electrode active materials (i.e., both are sodium-containing electrode active materials). In the rolling process, it is beneficial to take into account the first coating 1 and the second coating 2 to reach the target compaction density, and the problem of not being able to take into account the compaction density of the coatings on both sides in the rolling process due to the use of different types of electrode active materials can be avoided. Therefore, the embodiment of the present invention is conducive to the coating and formation of the first coating 1 and the second coating 2, thereby facilitating the preparation of the bipolar electrode sheet 100, and can further ensure the energy density and other properties of the electrode sheet.

[0054] In the embodiments of the present invention, unless otherwise specified, the processes of coating, drying and rolling may be conventional operations in the art and are not particularly limited thereto.

[0055] The present invention also provides a battery. Figure 1As shown, the battery includes the bipolar electrode sheet 100 described above or the bipolar electrode sheet 100 prepared according to the preparation method of the bipolar electrode sheet 100 described above.

[0056] The battery of the embodiment of the present invention is a bipolar battery, specifically a bipolar sodium ion battery, which has the same advantages as the above-mentioned bipolar electrode sheet 100 and will not be described in detail.

[0057] The use of the bipolar electrode sheet 100 is conducive to maintaining a high charge and discharge capacity and a high average battery voltage of the bipolar battery, and improving battery energy density and energy performance. In some embodiments, the charge capacity of the bipolar battery may be greater than or equal to 96 mAh / g, the discharge capacity may not be greater than or equal to 73 mAh / g, the average battery voltage of the bipolar battery may be between 8V and 10V, the energy may be greater than or equal to 647 mWh, and the energy density may be greater than or equal to 83 Wh / kg.

[0058] The test methods of the charging capacity, discharging capacity, average battery voltage, energy and energy density of the above-mentioned bipolar battery can be found in the following specific embodiments, which will not be described in detail here.

[0059] Continue to refer Figure 1 The battery further comprises a first single-sided pole piece 101 and a second single-sided pole piece 102, and the bipolar electrode piece 100 is located between the first single-sided pole piece 101 and the second single-sided pole piece 102; the first single-sided pole piece 101 comprises an electrode current collector 3, and a first coating 1 located on the side of the electrode current collector 3 facing the bipolar electrode piece 100; the second single-sided pole piece 102 comprises an electrode current collector 3, and a second coating 2 located on the side of the electrode current collector 3 facing the bipolar electrode piece 100; the first coating 1 in the bipolar electrode piece 100 faces the second single-sided pole piece 102, and the second coating 2 faces the first single-sided pole piece 101. The first single-sided pole piece 101, the bipolar electrode piece 100, and the second single-sided pole piece 102 are stacked along the thickness direction of the battery.

[0060] Continue to refer Figure 1 The first single-sided pole piece 101 includes a first pole ear 11 connected to the electrode collector 3 of the first single-sided pole piece 101 . The first pole ear 11 can be formed by the electrode collector 3 of the first single-sided pole piece 101 extending outward in the direction away from the first coating 1 along the length direction of the electrode collector 3 .

[0061] Continue to refer Figure 1 The second single-sided pole piece 102 includes a second pole ear 12 connected to the electrode collector 3 of the second single-sided pole piece 102 . The second pole ear 12 can be formed by the electrode collector 3 of the second single-sided pole piece 102 extending outward in the direction away from the second coating 2 along the length direction of the electrode collector 3 .

[0062] Continue to refer Figure 1 The battery may have one or more bipolar electrode sheets 100. When there are multiple bipolar electrode sheets 100, these bipolar electrode sheets 100 are located between the first single-sided electrode sheet 101 and the second single-sided electrode sheet 102, and these bipolar electrode sheets 100 are stacked in the same direction, that is, the first coating 1 of each bipolar electrode sheet 100 faces (towards) the second single-sided electrode sheet 102, and the second coating 2 of each bipolar electrode sheet 100 faces (towards) the first single-sided electrode sheet 101. Among them, the second coating 2 of the bipolar electrode sheet 100 closest to the first single-sided electrode sheet 101 faces the first coating 1 of the first single-sided electrode sheet 101, and the first coating 1 of the bipolar electrode sheet 100 closest to the second single-sided electrode sheet 102 faces the second coating 2 of the second single-sided electrode sheet 102.

[0063] Generally, the first coating 1 of the first single-sided pole piece 101 is the same as the first coating 1 in the bipolar electrode sheet 100, that is, the surface density of the two is the same, and the types and contents of components such as sodium-containing electrode active materials are basically the same; the second coating 2 of the second single-sided pole piece 102 is the same as the second coating 2 in the bipolar electrode sheet 100, that is, the surface density of the two is the same, and the types and contents of components such as sodium-containing electrode active materials are basically the same.

[0064] Continue to refer Figure 1 The first single-sided pole piece 101 is coated on one side, that is, only one side surface of the electrode collector 3 of the first single-sided pole piece 101 is coated with the first coating 1, and the other side surface of the first single-sided pole piece 101 (that is, the side surface of the electrode collector 3 facing away from the bipolar electrode sheet 100) is an empty foil area, and the empty foil area exposes the surface of the electrode collector 3 without coating.

[0065] Continue to refer Figure 1 The second single-sided pole piece 102 is coated on one side, that is, only one side surface of the electrode collector 3 of the second single-sided pole piece 102 is coated with the second coating 2, while the other side surface of the second single-sided pole piece 102 (that is, the side surface of the electrode collector 3 facing away from the bipolar electrode sheet 100) is an empty foil area, and the empty foil area exposes the surface of the electrode collector 3 without coating.

[0066] Specifically, the electrode current collector 3 of the first single-sided pole piece 101 includes aluminum foil, and the electrode current collector 3 of the second single-sided pole piece 102 includes aluminum foil.

[0067] Specifically, the first coating 1 of the first single-sided pole piece 101 and the second coating 2 of the second single-sided pole piece 102 can be formed by a coating method, that is, after the corresponding slurry is coated on one side surface of the electrode collector 3, the first single-sided pole piece 101 or the second single-sided pole piece 102 is obtained through processes such as drying and rolling. For details, please refer to the aforementioned method of forming the first coating 1 and the second coating 2 of the bipolar electrode sheet 100 by the coating method, and no further details will be given.

[0068] Continue to refer Figure 1 The battery further includes a diaphragm 4, which is spaced between two adjacent bipolar electrode sheets 100, and between the first single-sided electrode sheet 101 and the bipolar electrode sheet 100 closest to the first single-sided electrode sheet 101, and between the second single-sided electrode sheet 102 and the bipolar electrode sheet 100 closest to the second single-sided electrode sheet 102. That is, a diaphragm 4 is provided between two adjacent bipolar electrode sheets 100, a diaphragm 4 is provided between the first single-sided electrode sheet 101 and the bipolar electrode sheet 100 closest to the first single-sided electrode sheet 101, and a diaphragm 4 is provided between the second single-sided electrode sheet 102 and the bipolar electrode sheet 100 closest to the second single-sided electrode sheet 102.

[0069] In the embodiment of the present invention, the separator 4 used may be a conventional separator 4 in the art, such as a sodium ion battery separator 4. For example, the separator 4 may include cellulose and / or glass fiber, etc. Exemplarily, the separator 4 includes a cellulose separator 4 formed of cellulose and / or a glass fiber separator 4 formed of glass fiber.

[0070] Specifically, the above-mentioned battery includes a pole core, a packaging component 5 (or sealing component) that encapsulates the pole core, and an electrolyte. The packaging component 5 is arranged to form a cavity for accommodating the pole core. The pole core is located in the cavity of the packaging component 5. The electrolyte is injected into the cavity of the packaging component 5 to infiltrate the pole core. Among them, the pole core includes the above-mentioned first single-sided pole piece 101, the bipolar electrode piece 100, the diaphragm 4 and the second single-sided pole piece 102, the first single-sided pole piece 101 is located at the outermost side on one side in the thickness direction of the pole core, and the second single-sided pole piece 102 is located at the outermost side on the other side in the thickness direction of the pole core, respectively playing the role of lead-out pole ears, that is, the first pole ear 11 on the first single-sided pole piece 101 extends out of the packaging component 5 (that is, one end of the first pole ear 11 is connected to the electrode collector 3 of the first single-sided pole piece 101, and the other end is located on the outside of the packaging component 5 (that is, the side of the packaging component 5 away from the pole core)), and the second pole ear 12 on the second single-sided pole piece 102 extends out of the packaging component 5 (that is, one end of the second pole ear 12 is connected to the electrode collector 3 of the second single-sided pole piece 102, and the other end is located on the outside of the packaging component 5 (that is, the side of the packaging component 5 away from the pole core)).

[0071] Specifically, the first pole ear 11 and the second pole ear 12 can be arranged on the same side of the pole core, and can be arranged on the same side in the length direction of the pole core (also the length direction of the bipolar electrode sheet 100, the length direction of the first single-sided pole sheet 101 and the length direction of the second single-sided pole sheet 102) (e.g. Figure 1 shown).

[0072] Specifically, by packaging the electrode core through the packaging component 5, components such as the electrolyte inside the packaging component 5 can be prevented from contacting the external environment or adjacent components (the adjacent components are, for example, another battery adjacent to the battery when multiple batteries are assembled into a battery pack, or components in an electrical device adjacent to the battery when the battery is applied to the electrical device, etc.), thereby protecting the battery.

[0073] In the embodiment of the present invention, the packaging component 5 may be a conventional packaging material (or sealing material) in the art. For example, the packaging component 5 may include one or more adhesive materials such as PVDF and polymer resin.

[0074] In the embodiment of the present invention, the electrolyte used may be a conventional electrolyte in the art, specifically a non-aqueous electrolyte, and the electrolyte may include an organic solvent and a sodium salt, and the sodium salt may include sodium perchlorate (NaClO 4 ), sodium hexafluorophosphate (NaPF 6 ), sodium tetrafluoroborate (NaBF 4 ), etc., the organic solvent in the electrolyte may include ethylene carbonate (EC) and / or propylene carbonate (PC), etc.

[0075] In the embodiment of the present invention, the battery can be assembled by conventional methods in the art. For example, in a specific implementation, a plurality of bipolar electrode sheets 100 can be alternately stacked with the separator 4 in the same orientation to form a pole core (or internal pole core), and the first single-sided pole sheet 101 is stacked on the outermost side of one side in the thickness direction of the formed stacked structure, and the second single-sided pole sheet 102 is stacked on the outermost side of the other side, thereby forming a pole core; then, the outer peripheral area of ​​the pole core is sealed by a packaging component 5 to achieve packaging of the pole core, and then the electrolyte is injected into the cavity formed by the packaging component 5, thereby obtaining a battery (bipolar battery).

[0076] The embodiment of the present invention further provides a battery pack, including the above-mentioned battery. The battery has the same advantages as the above-mentioned bipolar electrode sheet 100, which will not be described in detail.

[0077] Generally, a battery pack includes a plurality of the above-mentioned batteries, which are connected as single batteries (or battery units) to form a battery pack. The batteries can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0078] The embodiment of the present invention further provides an electrical device, including the above-mentioned battery or the above-mentioned battery pack. The electrical device has the advantages corresponding to the above-mentioned bipolar electrode sheet 100, which will not be described in detail.

[0079] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in the field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablet computers, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without special restrictions.

[0080] The present invention is further described below through specific embodiments.

[0081] Example 1

[0082] (1) Preparation of bipolar electrode sheet (sodium vanadium phosphate (Na 3 V 2 (PO 4 ) 3 )Double-Sided Film

[0083] Weigh 6 kg of NMP, add 0.2 kg of PVDF, and stir until a uniform transparent liquid is formed; then add a mixed solution of CNT and NMP (the amount of the mixed solution added is 4 kg, and the mass concentration of CNT in the mixed solution is 5%), stir at high speed to obtain a uniform dispersion;

[0084] Weigh 10 kg of sodium vanadium phosphate (Na 3 V 2 (PO 4 ) 3 ), add the above dispersion, stir at high speed for 2h to obtain slurry; apply the above slurry on the surfaces of the opposite sides of the aluminum foil, dry, and roll to form coatings on the surfaces of the opposite sides of the aluminum foil (the coating on one side is the first coating (positive electrode coating) 1, and the coating on the other side is the second coating (negative electrode coating) 2) to obtain a bipolar electrode sheet; wherein the surface density of the first coating 1 is 200g / m 2 , the surface density of the second coating 2 is 200g / m 2 .

[0085] (2) Preparation of single-sided sheets (first single-sided pole sheet and second single-sided pole sheet)

[0086] (2-1) The slurry is applied to one side of the aluminum foil, dried, and rolled to form a coating on one side of the aluminum foil to obtain a single-sided sheet; wherein the surface density of the coating is 200 g / m 2 .

[0087] (2-2) Two single-sided sheets are prepared according to the process of (2-1), one of which is a first single-sided electrode sheet 101, and the coating therein is a first coating 1 (the surface density of the first coating 1 is 200 g / m 2 ); the other single-sided sheet is a second single-sided pole sheet 102, wherein the coating is a second coating 2 (the surface density of the second coating 2 is 200g / m 2 ).

[0088] (3) Cutting: Use a mold to cut the above-mentioned bipolar electrode sheet into bipolar electrode sheets with a size of 72 mm*61 mm (i.e., a length of 72 mm and a width of 61 mm), cut the first single-sided electrode sheet into a first single-sided electrode sheet 101 with a size of 72 mm*61 mm, and cut the second single-sided electrode sheet into a second single-sided electrode sheet 102 with a size of 72 mm*61 mm; wherein the first single-sided electrode sheet 101 has a first pole ear 11 (the first pole ear 11 is formed by the aluminum foil extending outward in the length direction of the aluminum foil in a direction away from the first coating 1), and the second single-sided electrode sheet 102 has a second pole ear 21 (the second pole ear 21 is formed by the aluminum foil extending outward in the length direction of the aluminum foil in a direction away from the second coating 2).

[0089] (4) Lamination: The first single-sided sheet 101-bipolar electrode sheet 100 (three sheets)-second single-sided sheet 102 are stacked and the diaphragm is alternately stacked to form a core. The core structure is as follows: Figure 1 shown.

[0090] Among them, Figure 1 As shown, the three bipolar electrode sheets 100 are located between the first single-sided electrode sheet 101 and the second single-sided electrode sheet 102 ; the first coating 1 of each bipolar electrode sheet 100 faces the second single-sided electrode sheet 102 , and the second coating 2 of each bipolar electrode sheet faces the first single-sided electrode sheet 101 .

[0091] Among them, the second coating 2 of the bipolar electrode sheet 100 closest to the first single-sided pole sheet 101 faces the first coating 1 of the first single-sided pole sheet 101, and the first coating 1 of the bipolar electrode sheet 100 closest to the second single-sided pole sheet 102 faces the second coating 2 of the second single-sided pole sheet 102.

[0092] The diaphragm 4 is spaced between two adjacent bipolar electrode sheets 100 , between the first single-sided electrode sheet 101 and the bipolar electrode sheet 100 closest to the first single-sided electrode sheet 101 , and between the second single-sided electrode sheet 102 and the bipolar electrode sheet 100 closest to the second single-sided electrode sheet 102 .

[0093] (5) Sealing: After the electrode core is baked, PVDF is used to seal the electrode pieces on all sides (i.e., the electrode core is encapsulated by a packaging component (or PVDF sealing layer) 5 formed by PVDF, the electrode core is located in a cavity surrounded by the packaging component 5, and the first electrode ear 11 of the first single-sided electrode piece 101 and the second electrode ear 12 of the second single-sided electrode piece 102 are arranged on the same side of the electrode core and both extend out of the packaging component 5), and each electrochemical unit is formed into a separate cavity (the area between each two adjacent current collectors (aluminum foils) is recorded as one electrochemical unit, such as Figure 1 As shown, the pole core of this embodiment 1 has a total of 4 electrochemical units).

[0094] (6) Liquid injection: Use a syringe to inject an equal amount of electrolyte into each cavity through the PVDF sealing layer to prepare a sodium ion battery; wherein the electrolyte is composed of PC and NaClO 4 Prepared with NaClO in the electrolyte 4 The concentration is 1 mol / L.

[0095] Examples 2 to 7: The difference from Example 1 is that the surface density of the first coating (positive electrode surface density in Table 1), the surface density of the second coating (negative electrode surface density in Table 1), the ratio of the surface density of the first coating and the second coating, the type of electrode active material in the first coating, the type of electrode active material in the second coating and other conditions are different, see Table 1 for details. Except for the differences shown in Table 1, the other conditions are the same as those in Example 1.

[0096] Comparative Example 1: The difference from Example 1 is that the electrode active material in the second coating in Comparative Example 1 is hard carbon (i.e., the bipolar electrode sheet in Comparative Example 1 is a sodium vanadium phosphate / hard carbon double-sided sheet, and the second single-sided electrode sheet is a hard carbon single-sided sheet), and the other conditions are the same as those in Example 1;

[0097] The preparation process of the sodium vanadium phosphate / hard carbon double-sided sheet, hard carbon single-sided sheet, and sodium ion battery in Comparative Example 1 is as follows:

[0098] (1) Preparation of sodium vanadium phosphate / hard carbon double-sided sheet (bipolar electrode sheet)

[0099] Weigh 6 kg of NMP, add 0.2 kg of PVDF, and stir until a uniform transparent liquid is formed; then add a mixed solution of CNT and NMP (the amount of the mixed solution added is 4 kg, and the mass concentration of CNT in the mixed solution is 5%), stir at high speed to obtain a uniform dispersion;

[0100] Weigh 10 kg of sodium vanadium phosphate (Na 3 V 2 (PO 4 ) 3), add the above dispersion, stir at high speed for 2h to obtain a slurry; apply the above slurry on one side of the aluminum foil, dry it to form a positive electrode coating (first coating) on ​​one side of the aluminum foil, and obtain a sodium vanadium phosphate single-sided sheet; wherein the surface density of the first coating is 200g / m 2 ;

[0101] Weigh 12.2 kg of water, add 160 g of sodium carboxymethyl cellulose (CMC), and stir until a uniform liquid is formed; then add 100 g of acetylene black, stir at high speed to obtain a uniform dispersion; weigh 10 kg of hard carbon, add it to the above dispersion, and stir at high speed for 3 hours; add 340 g of SBR solution with a mass concentration of 40%, stir for 0.5 hours, then add 300 g of NMP, stir for 0.5 hours, and stir at low speed to obtain a negative electrode slurry; apply the negative electrode slurry to the other side of the aluminum foil of the sodium vanadium phosphate single-sided sheet, dry it to form a negative electrode coating (second coating) on ​​the other side of the aluminum foil, and after rolling, obtain a sodium vanadium phosphate / hard carbon double-sided sheet; wherein the surface density of the negative electrode coating (second coating) is 200 g / m 2 .

[0102] (2) Preparation of a hard carbon single-sided sheet (second single-sided electrode sheet): The negative electrode slurry is applied to one side of an aluminum foil, dried, and rolled to form a negative electrode coating (second coating) on ​​one side of the aluminum foil to obtain a hard carbon single-sided sheet; wherein the surface density of the second coating is 200 g / m 2 .

[0103] (3) Using the above-mentioned sodium vanadium phosphate single-sided sheet as the first single-sided electrode sheet, the sodium vanadium phosphate / hard carbon double-sided sheet as the bipolar electrode sheet, and the hard carbon single-sided sheet as the second single-sided electrode sheet, refer to the cutting and lamination process in Example 1 to prepare a sodium ion battery.

[0104] Comparative Examples 2 and 3: Compared with Comparative Example 1, the surface density of the second coating layer (the negative electrode surface density in Table 1) and the other conditions are the same as those in Example 1.

[0105] The coating surface density of the electrode sheets prepared in the embodiments and comparative examples, the thickness of the electrode sheets, and the voltage and capacity of the sodium ion battery were tested according to the following process. The test results are shown in Tables 1 and 2.

[0106] (1) Surface density test of the first coating or second coating of the electrode sheet

[0107] The surface density of the first coating layer (positive electrode surface density) ρ 1 =m 1 / S,m 1 is the mass of the first coating, S is the surface area of ​​one side of the electrode sheet in the thickness direction;

[0108] The surface density of the second coating layer (negative electrode surface density) ρ 2 =m 2 / S,m 2 is the mass of the second coating, S is the surface area of ​​one side of the electrode sheet in the thickness direction;

[0109] For the first single-sided electrode sheet or the second single-sided electrode sheet, when testing the surface density of the first coating or the second coating, a sampler is used to take an electrode sheet of a certain area S and measure the total mass m of the electrode sheet. 0 , then scrape off the coating on the surface of the current collector (foil), and then measure the mass m of the remaining current collector 3 , the total mass of the electrode sheet m 0 Deduct the current collector mass m 3 The mass value after 0 -m 3 ) is the coating mass (m 1 or m 2 ), and then divided by the electrode sheet area S to obtain the surface density of the coating.

[0110] For a double-sided sheet, when testing the surface density of the coating on either side of the current collector (coating to be tested), the mass of the coating to be tested = the total mass of the electrode sheet m 0 - The mass of the current collector m 3 -The mass of the coating on the other side of the current collector. During the test, a sampler is used to take an electrode sheet of a certain area S, and after scraping off the coating on the other side, the mass of the coating to be tested is measured by referring to the above process, and then its surface density is calculated.

[0111] (2) Electrode sheet thickness: The thickness of the bipolar electrode sheet was tested using a micrometer.

[0112] (3) Test of charging capacity, discharging capacity, average battery voltage and energy of sodium ion batteries: The D340A Blue Electric Precision Battery Tester was used to test the sodium ion battery. The battery was charged to 16.0 V at a constant current and voltage of 0.1 C, and then charged to a cut-off current of 0.02 C at a constant voltage to obtain the charging capacity. The battery was discharged to 4.0 V at a constant current of 0.1 C to obtain the discharge capacity, and the average voltage and energy Q were read on the test equipment.

[0113] Among them, volume energy density: divide the above energy Q by the volume V of the sodium ion battery 0 , that is, the energy density of the battery (i.e., energy density = Q / V 0 ), the volume of the sodium-ion battery V 0 It is the product of the length, width and thickness of the sodium ion battery. The thickness of the sodium ion battery is calculated based on the thickness of the electrode sheet.

[0114] Table 1

[0115]

[0116] Table 2

[0117]

[0118] As can be seen from Table 1, in the bipolar sodium ion batteries of Comparative Examples 1 to 3, the active materials in the positive electrode coating are different from the active materials in the negative electrode coating. The active material in the positive electrode coating is sodium vanadium phosphate, and the active material in the negative electrode coating is hard carbon. The negative electrode uses hard carbon material, which has a higher specific capacity, but the side reaction of SEI formation and other side reactions are more serious, and the loss of active sodium ions is more, and its discharge capacity is very low; on the other hand, because the potential of its main reaction is low, the full battery voltage is high. In general, the energy density of the bipolar sodium ion batteries of Comparative Examples 1 to 3 is low.

[0119] In addition, in Comparative Examples 1 to 3, the active material in the positive electrode coating is different from the active material in the negative electrode coating, the positive electrode slurry used to form the positive electrode coating is an oil-based slurry, and the slurry used to form the negative electrode coating is an aqueous slurry. In the preparation process of the bipolar electrode sheet, the atmosphere generated during the drying process of the two types of slurries will affect each other, which will have an adverse effect on the positive and negative electrode active materials and auxiliary materials such as conductive agents and binders. At the same time, the positive and negative electrode active materials of the bipolar electrode sheet are different, and the coating surface density on both sides of the aluminum foil cannot be taken into account during rolling. For example, when the surface density of the positive electrode coating meets the standard, the surface density of the negative electrode coating cannot meet the standard, which is also an important factor affecting the energy density and energy and other electrochemical properties of the bipolar sodium ion battery.

[0120] Compared with Comparative Examples 1 to 3, in the bipolar sodium ion batteries of Examples 1 to 8, the positive electrode coating and the negative electrode coating use the same type of electrode active material (both are sodium-containing electrode active materials), which can effectively overcome the defects of Comparative Examples 1 to 3, while maintaining the high charge and discharge capacity, average battery voltage and energy of the bipolar sodium ion battery, and improving the energy density of the bipolar sodium ion battery.

[0121] Furthermore, relative to Example 4 and Example 5, Examples 1 to 3 further control the difference in surface density between the first coating and the second coating in the bipolar sodium ion battery within a smaller range, which is beneficial for the first coating and the second coating in the bipolar electrode sheet to have a more similar degree of ductility. In the preparation process of the bipolar electrode sheet, the problem of bending of the electrode sheet due to different degrees of ductility during rolling is further alleviated, and the performance of the bipolar sodium ion battery is further optimized. Specifically, the bipolar sodium ion batteries of Examples 1 to 3 have higher discharge specific capacity and average voltage, and have higher energy density and energy. Among them, the reason for analysis is that, relatively speaking, the negative electrode surface density in Example 4 is relatively low. During the charging process, SEI is formed and other side reactions cause more active sodium ions to be lost, resulting in a low discharge capacity. Although the discharge voltage (battery average voltage) has certain advantages, the overall energy density is low; relatively speaking, the negative electrode surface density in Example 5 is relatively high. Although it can avoid excessive consumption of active sodium ions when SEI is formed, it can improve the discharge capacity to a certain extent compared with Example 4, but due to its high surface density, the negative electrode uses a higher platform capacity during charging and discharging. Therefore, the average discharge voltage of Implementation 5 is low, and its energy density is also low.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bipolar electrode sheet, characterized in that: The invention comprises an electrode current collector, a first coating layer located on one side surface of the electrode current collector, and a second coating layer located on the other side surface of the electrode current collector; the first coating layer and the second coating layer each independently comprise a sodium-containing electrode active material.

2. The bipolar electrode sheet according to claim 1, characterized in that: The sodium-containing electrode active material in the first coating layer is the same as the sodium-containing electrode active material in the second coating layer.

3. The bipolar electrode sheet according to claim 1 or 2, characterized in that: The sodium-containing electrode active material includes a sodium-containing phosphate.

4. The bipolar electrode sheet according to claim 3, characterized in that: The sodium-containing phosphate includes one or more of Na3V2(PO4)3, NaVPO4F, and Na3V2(PO4)2F3.

5. The bipolar electrode sheet according to claim 1 or 2, characterized in that: The electrode current collector includes aluminum foil.

6. The bipolar electrode sheet according to claim 1, characterized in that: The ratio of the surface density of the first coating layer to the surface density of the second coating layer is 0.8-1.

2.

7. The bipolar electrode sheet according to claim 1 or 6, characterized in that: The surface density of the first coating is 100-250 g / m 2 The surface density of the second coating is 80 to 300 g / m 2 .

8. A method for preparing a bipolar electrode sheet according to any one of claims 1 to 7, characterized in that: include: The first coating layer is formed on one side of the electrode current collector by a first slurry and the second coating layer is formed on the other side of the electrode current collector by a second slurry to obtain the bipolar electrode sheet. The first slurry contains the sodium-containing electrode active material and an organic solvent, and the second slurry contains the sodium-containing electrode active material and an organic solvent.

9. The method for preparing a bipolar electrode sheet according to claim 8, characterized in that: The organic solvent in the first slurry is the same as the organic solvent in the second slurry.

10. The method for preparing a bipolar electrode sheet according to claim 8 or 9, characterized in that: The organic solvent in the first slurry includes N-methylpyrrolidone; And / or, the organic solvent in the second slurry includes N-methylpyrrolidone.

11. A battery, characterized in that: The invention comprises the bipolar electrode sheet as claimed in any one of claims 1 to 7 or the bipolar electrode sheet prepared by the method for preparing the bipolar electrode sheet as claimed in any one of claims 8 to 10.

12. The battery according to claim 11, characterized in that It also includes a first single-sided pole piece and a second single-sided pole piece, wherein the bipolar electrode piece is located between the first single-sided pole piece and the second single-sided pole piece; The first single-sided electrode sheet includes the electrode current collector and the first coating located on a side of the electrode current collector facing the bipolar electrode sheet; The second single-sided electrode sheet includes the electrode current collector and the second coating located on a side of the electrode current collector facing the bipolar electrode sheet; The first coating in the bipolar electrode sheet faces the second single-sided electrode sheet, and the second coating faces the first single-sided electrode sheet.

13. The battery according to claim 12, characterized in that The first single-sided pole piece includes a first pole lug connected to the electrode current collector of the first single-sided pole piece, and the second single-sided pole piece includes a second pole lug connected to the electrode current collector of the second single-sided pole piece.

14. A battery pack, characterized in that: A battery comprising any one of claims 11 to 13.

15. An electrical equipment, characterized in that: The invention comprises the battery according to any one of claims 11 to 13 or the battery pack according to claim 14.

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