Positive electrode plate and its manufacturing method, battery and power consumption device

Abstract

The present invention provides a positive electrode plate, a manufacturing method thereof, a battery, and a power consumption device. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector and containing a positive electrode active material, the positive electrode active material layer containing a sodium-containing positive electrode active material. The positive electrode plate has a thickness of D max / D min is 104.5% to 300%, and after assembling the positive electrode plate and the negative electrode plate into a battery, the thickness of the positive electrode plate when the battery is at 0% SOC is D max The thickness of the positive electrode plate when the battery is at 100% SOC is D min Here, the negative electrode plate includes a negative electrode current collector, and has a sodium metal layer on at least one surface of the negative electrode current collector when the battery is at 100% SOC.

Description

[Technical Field]

[0001] The present disclosure relates to the field of batteries, and more particularly to positive electrode plates and methods for manufacturing the same, batteries and power consuming devices. [Background technology]

[0002] As the application of lithium-ion battery technology in markets such as consumer electronics, electric vehicles, and energy storage gradually expands, the problem of lithium resource shortages is becoming more prominent. Sodium-based batteries have gradually attracted attention due to the sufficiently high abundance of sodium element on Earth, and play an important strategic role in cost-sensitive applications such as energy storage. With the development and advancement of electrolyte and its additive technology and surface modification technology, the problem of sodium dendrite growth due to non-uniform deposition on metal surfaces, which has long plagued the academic community, has been significantly improved, and high-energy density sodium metal anodes have once again come into public view.

[0003] Therefore, current positive electrode plates and their manufacturing methods, batteries and power consuming devices still need improvement. Summary of the Invention

[0004] According to one aspect of the present application, the present application proposes a positive electrode plate, the positive electrode plate including a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material, the positive electrode active material layer including a sodium-containing positive electrode active material, and the thickness of the positive electrode plate is D max / D min is 104.5% to 300%, and after assembling the positive electrode plate and the negative electrode plate into a battery, the thickness of the positive electrode plate when the battery is at 0% SOC is set to D max The thickness of the positive electrode plate when the battery is at 100% SOC is defined as D minSpecifically, the negative electrode plate includes a negative electrode current collector, and when the battery is at 100% SOC, a sodium metal layer is provided on at least one surface of the negative electrode current collector. The positive electrode plate in the present application can relieve the stress change caused by the volume change during the charge and discharge process of the negative electrode plate, further reduce the volume expansion during the operation process of the battery, and improve the structural stability of the battery.

[0005] According to an embodiment of the present application, the porosity of the positive electrode active material layer is 25% to 50%. Thereby, the stress change caused by the expansion and contraction of the negative electrode plate can be relieved by the hole structure of the positive electrode plate.

[0006] According to an embodiment of the present application, the positive electrode active material includes a layered oxide, and the layered oxide satisfies the chemical formula Na x M y O2, where 0 < x ≤ 4.5, 0 < y ≤ 1, the M element includes at least one of Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce. Preferably, the M element includes at least one of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, and Zn. Thereby, the manufacturing cost of the positive electrode plate can be reduced, and the energy density of the positive electrode plate can be improved.

[0007] According to an embodiment of the present application, the positive electrode active material includes a polyanion-type compound. The cation element of the polyanion-type compound includes at least one of Ni, V, Co, Fe, Mn, and Cu. The anion of the polyanion-type compound is F - , PO4 3- , P2O7 4- and (PO4)2P2O7 10- and includes at least one of them. Preferably, the anion of the polyanion-type compound includes F - . Thereby, the manufacturing cost of the positive electrode plate can be reduced, and the energy density of the positive electrode plate can be improved.

[0008] According to an embodiment of the present application, the anion of the polyanion-type compound is PO43- and P2O7 4- and the P2O7 in the polyanion type compound. 4- and the aforementioned PO4 3- The molar ratio of the P2O7 in the polyanion compound is 0.1 to 5. 4- and the aforementioned PO4 3- The molar ratio of is 0.1 to 3. This makes it possible to further reduce the manufacturing cost of the positive electrode plate and improve the energy density of the positive electrode plate.

[0009] According to an embodiment of the present application, the positive electrode active material layer further comprises a sodium supplement additive, the mass fraction of the positive electrode active material in the positive electrode active material layer is 50 wt% to 98 wt%, and the mass fraction of the sodium supplement additive in the positive electrode active material layer is 2 wt% to 50 wt%, whereby the sodium supplement additive can increase the energy density of the battery, while the lithium supplement additive can be used to compensate for sodium consumption occurring during cycling and improve the cycling performance of the battery.

[0010] According to an embodiment of the present application, the sodium supplement additive comprises at least one of Na2S, NaN3, Na2NiO2, NaC6H5O7, Na2O, Na2O2, Na6CoO4, Na5FeO4, Na2C2O4, Na2C4O4, Na2C3O5, Na2C4O6 and Na2C6O6, which can further improve the energy density and cycle performance of the battery.

[0011] According to an embodiment of the present application, the thickness of the negative electrode plate is d max / d min is 100% to 700%, wherein the d max is the thickness of the negative electrode plate when the battery is at 100% SOC, and d min is the thickness of the negative electrode plate when the battery is at 0% SOC, so that the positive electrode plate can meet the requirements of a negative electrode plate with a relatively large thickness change rate in the battery.

[0012] According to another aspect of the present application, the present application proposes a method for manufacturing the above-mentioned positive electrode plate, the method comprising providing a positive electrode current collector, providing a positive electrode slurry, and coating the positive electrode slurry on at least one surface of the positive electrode current collector to form a positive electrode active material layer, thereby having all the features and advantages of the above-mentioned positive electrode plate, which will not be further described herein.

[0013] According to an embodiment of the present application, preparing the positive electrode slurry includes uniformly mixing a positive electrode active material and a sodium supplement additive in a solvent, and after forming the positive electrode active material layer, assembling the positive electrode plate and the negative electrode plate into a battery and performing a chemical conversion treatment, thereby further improving the porosity of the positive electrode active material layer.

[0014] According to an embodiment of the present application, the method further includes, before coating at least one surface of the positive current collector with the positive electrode slurry, providing sodium foil on the surface of the positive current collector on which the positive electrode slurry is to be coated, thereby producing a positive electrode plate having a relatively high energy density.

[0015] According to yet another aspect of the present application, the present application proposes a battery, the battery including a positive electrode plate, a negative electrode plate, and a separator located between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate is the positive electrode plate described above and / or a positive electrode plate obtained by employing the method described above, the negative electrode plate includes a negative electrode current collector, and the thickness of the negative electrode plate is d max / d min is 100% to 700%, wherein the d max is the thickness of the negative electrode plate when the battery is at 100% SOC, and d min is the thickness of the negative plate when the battery is at 0% SOC, whereby this battery has all the features and advantages of the positive plate and method of manufacturing the positive plate described above, which will not be further described herein.

[0016] According to yet another aspect of the present application, the present application proposes a power consuming device, which includes the positive electrode plate and / or the positive electrode plate obtained by employing the method and / or the battery, thereby having all the features and advantages of the positive electrode plate, the method for manufacturing the positive electrode plate, and the battery, which will not be further described herein. [Brief explanation of the drawings]

[0017] The above and / or additional aspects and advantages of the present application will become more apparent and easier to understand from the following description of the embodiments taken in conjunction with the drawings, in which: [Figure 1] 1 shows a structural schematic diagram of a battery according to one embodiment of the present application at 0% SOC. [Figure 2] 1 shows a structural schematic diagram of a battery according to one embodiment of the present application at 100% SOC. [Figure 3] 1 shows a structural schematic diagram of a battery according to one embodiment of the present application at 60% SOC. [Figure 4] 1 shows a schematic diagram of a battery according to one embodiment of the present application. [Figure 5] 5 shows an exploded view of the battery of one embodiment of the present application shown in FIG. 4. [Figure 6] 1 shows a schematic diagram of a battery module according to one embodiment of the present application. [Figure 7] 1 shows a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 8] 8 shows an exploded view of the battery pack of one embodiment of the present application shown in FIG. 7. [Figure 9] 1 shows a schematic diagram of a power consuming device using a battery as a power source according to one embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, the embodiments of the present application will be described in detail, and examples of the embodiments are shown in the drawings, where the same or similar reference numerals always represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are illustrative and are used only to interpret the present application, and should not be understood as limitations on the present application.

[0019] In this application, SOC refers to the state of charge of a battery and can reflect the remaining capacity of the battery. It is numerically defined as the ratio of the remaining capacity to the battery capacity, typically expressed as a percentage, ranging from 0% to 100%. "100% SOC" refers to the state when a battery is charged to its maximum design voltage at a constant current of 1 C and then charged to a constant voltage of 0.05 C. This includes the state after standing (typically 10 minutes), both of which are considered to be 100% SOC, i.e., a fully charged state. "60% SOC" refers to the state when an electrochemical device is charged to 60% SOC at a constant current. The battery can be adjusted to 60% SOC according to the following method: first fully charge the battery, then discharge it at a constant current of 1 C for 12 minutes, at which point the battery is in a 60% SOC state, and also includes the state after standing (typically 10 minutes). "0% SOC" refers to the state when the remaining capacity of the battery is zero, i.e., a fully discharged state.

[0020] Taking a "negative electrode-less" sodium metal battery as an example, referring to Figures 1 to 3, during the charging process of the battery, when the battery is in a fully discharged state, the negative electrode plate only includes negative electrode current collector 11. During the charging process, sodium ions in positive electrode active material layer 22 gradually leave and deposit on the surface of negative electrode current collector 11, gradually forming sodium metal layer 12 on the surface of negative electrode current collector 11, i.e., gradually increasing the thickness of the negative electrode plate, which reaches its maximum thickness when the battery is fully charged. Furthermore, while the volume of other components in the battery remains constant, as the thickness of the negative electrode plate gradually increases during charging, the utilization rate of the battery's internal space increases, and the internal structure of the battery exerts greater pressure on the battery case, ultimately deforming the battery case and failing to meet the surface flatness requirements. This will further affect the assembly of the battery module and significantly increase the fatigue strength of the functional assembly. The relatively large volume expansion will cause the adhesive layer between adjacent batteries to fall off or peel off, which will further damage the battery module structure.

[0021] For a "no-negative electrode" sodium metal battery, the maximum thickness change of the negative electrode plate due to sodium deposition or desorption on the surface of the negative electrode current collector can reach several times the initial thickness value. Based on this, by selecting a positive electrode plate that is opposite to the thickness change rule of the negative electrode plate of a "no-negative electrode" metal battery, the stress caused by the expansion and contraction of the negative electrode plate can be effectively alleviated. Specifically, the positive electrode plate proposed in this application has a minimum thickness when the battery is in a fully charged state, a maximum thickness when the battery is in a fully discharged state, and a gradual increase in thickness as the battery transitions from a fully charged state to a fully discharged state, and a gradual decrease in thickness as the battery transitions from a fully discharged state to a fully charged state. Conversely, the negative electrode plate has a maximum thickness when the battery is in a fully charged state, and a minimum thickness when the battery is in a fully discharged state, and a gradual increase in thickness as the battery transitions from a fully discharged state to a fully charged state, and a gradual decrease in thickness as the battery transitions from a fully charged state to a fully discharged state. In the "negative electrode-less" metal battery obtained by selecting and assembling the positive electrode plate in this application, the thickness of the negative electrode plate continuously increases and the thickness of the positive electrode plate continuously decreases adaptively during the charging process, and the thickness of the negative electrode plate continuously decreases and the thickness of the positive electrode plate continuously increases adaptively during the discharging process, thereby achieving the effect of matching the increase and decrease in thickness of the plates, and further effectively mitigating the volume change of the negative electrode plate during the charging and discharging process, keeping the internal stress of the battery relatively stable during the charging and discharging process, significantly improving the structural stability of the battery and further improving the service life of the battery.

[0022] In the description of this application, a "negative electrode-less" metal battery refers to a battery that does not add any negative electrode active material during the manufacturing process and uses only the negative electrode current collector as a nominal negative electrode plate. However, this negative electrode current collector does not have the function of a negative electrode plate. After charging is completed, the metal active ions in the positive electrode active material layer migrate to the surface of the negative electrode current collector and deposit on the surface of the negative electrode current collector to form a sodium metal layer, and only then does the battery truly have a negative electrode plate.

[0023] In some embodiments, a "negative electrode-less" sodium battery refers to a battery constructed without an active negative electrode material layer being applied to the negative electrode plate during the battery manufacturing process. For example, a negative electrode active material layer is not applied to the negative electrode current collector by a coating or deposition process during the battery manufacturing process. During the initial charge, sodium ions gain electrons on the negative electrode side, and metallic sodium deposits on the surface of the negative electrode current collector to form a sodium metal phase. During discharge, the metallic sodium transitions to sodium ions and returns to the positive electrode plate, enabling cyclic charge and discharge. Compared to other sodium batteries, the "negative electrode-less" sodium battery can achieve a higher energy density due to the absence of an active negative electrode material layer.

[0024] For example, in a "negative electrode-less" sodium battery, a functional coating may be applied to the surface of the negative electrode current collector of the negative electrode plate, which can improve battery performance.

[0025] In some embodiments, to improve battery performance, the negative electrode plate may include a negative electrode current collector and a functional coating disposed on at least one surface of the negative electrode current collector, and the functional coating may include a carbon material coating (including single-walled conductive carbon tubes, multi-walled conductive carbon tubes, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, soft carbon, and hard carbon, etc.), a lithium-philic / sodium-philic metal composite coating, etc.

[0026] According to one aspect of the present application, the present application proposes a positive electrode plate, the positive electrode plate including a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material, the positive electrode active material including a sodium-containing positive electrode active material, and a thickness of the positive electrode plate: D max / D min is 104.5% to 300%, and after assembling the positive electrode plate and the negative electrode plate into a battery, the thickness of the positive electrode plate when the battery is at 0% SOC is D maxThe thickness of the positive electrode plate when the battery is at 100% SOC is D min Here, the negative electrode plate includes a negative electrode current collector, and when the battery is at 100% SOC, the negative electrode current collector has a sodium metal layer on at least one surface thereof. max / D min When the volume change rate of the positive electrode active material layer is too large, the positive electrode active material layer is easily powdered during the charge / discharge process and even falls off from the surface of the positive electrode current collector, resulting in the thickness D max / D min If the volume change rate of the positive electrode active material layer is less than 4.5%, the volume change rate of the positive electrode active material layer is too small to reduce the volume change of the negative electrode plate. max / D min When the thickness of the positive electrode plate satisfies the condition of 104.5% to 300%, the positive electrode plate can effectively relieve the expansion stress caused by the volume change of the negative electrode plate during the charge and discharge process of the battery, which significantly improves the structural stability of the battery and further improves the service life of the battery.

[0027] According to some embodiments of the present application, a positive electrode plate has a hole structure, for example, when the positive electrode active material layer has a hole structure, the hole structure provides a compressible space for the positive electrode active material layer, and this compressible space can spring back after the external force is removed. When the positive electrode active material layer is compressed by an external force, the thickness of the positive electrode active material layer is reduced, and the thickness of the entire positive electrode plate can be reduced. Therefore, when the positive electrode plate is subjected to the compressive force of the negative electrode plate during charging, the thickness of the positive electrode plate is reduced, thereby alleviating the expansion stress generated in the negative electrode plate during charging. For example, the porosity of the positive electrode active material layer may be 25% to 50%. When the porosity of the positive electrode active material layer is less than 25%, the positive electrode active material layer has relatively poor compressibility and is unable to effectively alleviate the expansion stress of the negative electrode plate. When the porosity of the positive electrode active material layer is greater than 50%, the positive electrode active material layer has too many voids and the pore diameter is too large, resulting in poor contact between the positive electrode active material particles, which further increases the contact resistance and deteriorates the performance of the positive electrode plate. In addition, there are also other problems, such as a relatively low energy density of the positive electrode plate.

[0028] The porosity of the positive electrode active material layer can be determined by the gas replacement method. The percentage of the hole volume in the positive electrode active material layer occupying the total volume of the positive electrode active material layer is the porosity of the positive electrode active material layer. Specifically, according to some embodiments of the present application, referring to GB / T 24586-2009, it can be determined by the following steps, that is, immersing the positive electrode plate in ethyl methyl carbonate (EMC) for cleaning, adopting an AccuPyc II 1340 device, measuring by using the gas replacement method, and the calculation formula is the porosity ρ of the positive electrode plate 総 =(V - V0) / V 総 ×100%, where V0 is the true volume and V is the apparent volume, and the porosity ρ of the positive electrode active material layer = ρ 総 ×V / (V - V 集電体 ) and here V 集電体 is the volume of the current collector. [[ID=​​​​​​​​​According to some embodiments of the present application, the positive electrode active material may include a polyanion-type compound, and the cation element of the polyanion-type compound may include at least one of Ni, V, Co, Fe, Mn, and Cu. According to some other embodiments of the present application, the cation of the polyanion-type compound may include at least one of Ni, V, Co, Fe, Mn, and Cu. 2+ , Ni 3+ , Co 2+ , Co 3+ , Fe 2+ , Fe 3+ , Mn 3+ , V 3+ and Cu 2+ and the anion of the polyanionic compound may comprise at least one of F - , PO4 3- , P2O7 4- and (PO4)2P2O7 10- According to some further embodiments of the present application, the anion of the polyanionic compound comprises at least one of F - The polyanion type compound has a crystal structure that is mainly an olivine structure. The polyanion type compound has an excellent cycle life, a relatively high output voltage, and excellent structural stability. The polyanion type compound has a small volume change and a small phase change during the process of absorbing and releasing sodium ions, and has a relatively good long-term cycle stability.

[0031] According to some embodiments of the present application, the anion of the polyanionic compound is PO4 3- and P2O7 4- When it contains P2O7 in polyanion type compounds, 4- and PO4 3- The molar ratio of P2O7 to P2O7 in the polyanion type compound may be 0.1 to 5. 4- and PO4 3- The molar ratio of P2O7 in the polyanion type compound may be 0.1 to 3. 4- and PO4 3- When the molar ratio of is in the range of 0.1 to 5, the polyanion type compound has a relatively high specific capacity and excellent cycle performance.

[0032] According to some embodiments of the present application, the positive electrode active material layer may further include a sodium supplement additive, and the mass fraction of the positive electrode active material in the positive electrode active material layer may be 50 wt% to 98 wt%. The mass fraction of the sodium supplement additive in the positive electrode active material layer may be 2 wt% to 50 wt%. In the present application, the sodium supplement additive compensates for the loss of active sodium caused when the battery forms an SEI during the initial charge / discharge process, allowing the battery to have sufficient reversibly active sodium during subsequent cycles and increasing the energy density of the battery. The sodium supplement additive may also be used to compensate for sodium consumption occurring during cycling and improve the cycle performance of the battery. According to some other embodiments of the present application, when a sodium-free and / or low-sodium positive electrode active material is selected, the content of the sodium supplement additive may be appropriately increased so that the energy density of the positive electrode plate meets the battery design requirements. When a typical sodium-containing positive electrode active material is selected, the content of the sodium supplement additive may be appropriately reduced so that the energy density of the positive electrode plate meets the battery design requirements. Those skilled in the art can make a selection according to the actual situation.

[0033] According to some embodiments of the present application, a volatile sodium supplement additive can be selected to generate gas during the battery formation process, which can be released from the positive electrode active material layer, and further provide a pore structure in the positive electrode active material layer, thereby improving the porosity of the positive electrode active material layer. For example, the sodium supplement additive may include at least one of Na2S, NaN3, Na2NiO2, NaC6H5O7, Na2O, Na2O2, Na6CoO4, Na5FeO4, Na2C2O4, Na2C4O4, Na2C3O5, Na2C4O6, and Na2C6O6.

[0034] According to some embodiments of the present application, the thickness of the positive electrode current collector is 5 μm to 60 μm, and the thickness of the positive electrode active material layer is 50 μm to 350 μm. When the thicknesses of the positive electrode current collector and the positive electrode active material layer are within the above ranges and the porosity of the positive electrode active material layer is 25% to 50%, the thickness of the positive electrode plate is such that the thickness change during the charge and discharge process is D max / D min may satisfy the condition that the ratio is 104.5% to 300%.

[0035] According to some embodiments of the present application, the positive electrode active material layer on the positive electrode plate of the present application can be compressed and spring back, so that when the thickness of the negative electrode plate increases during charging, the thickness of the positive electrode plate can be adaptively reduced, and when the thickness of the negative electrode plate decreases during discharging, the thickness of the positive electrode plate can be adaptively increased, thereby keeping the internal stress of the battery relatively stable during charging and discharging. max / D min When the thickness of the positive electrode plate satisfies the condition of 104.5% to 300%, the battery case has already reserved some space during structural design, and this reserved space may be used to relieve stress caused by volume expansion during the charge and discharge process of the battery. Specifically, in the initial stage when expansion of the negative electrode plate occurs, the reserved space of the battery case may be used to relieve relatively minor volume expansion of the negative electrode plate. As the volume of the negative electrode plate further expands and increases, after the positive electrode plate is subjected to pressure from the negative electrode plate, the positive electrode plate accordingly contracts in volume, thereby further relieving the stress caused by the volume expansion of the negative electrode plate. The reserved space of the battery case and the positive electrode plate capable of compression and springback cooperate to relieve stress caused by a negative electrode plate with a relatively large volume change rate during the charge and discharge process, for example, d max / d min It may be used to mitigate the expansion and contraction changes during the charge and discharge process of a negative electrode plate whose thickness satisfies the condition of 100% to 700% (d max is the thickness of the negative electrode plate when the battery is at 100% SOC, and d min is the thickness of the negative electrode plate when the battery is at 0% SOC). According to some other embodiments of the present application, the thickness of the negative electrode plate is max / d min is between 120% and 400%.

[0036] According to some embodiments of the present application, the thickness of the negative electrode current collector may be 5 μm to 600 μm, and the thickness of the sodium metal layer on the surface of the negative electrode current collector may be 0 μm to 200 μm. When the thicknesses of the negative electrode current collector and the sodium metal layer are within the above ranges, the thickness of the negative electrode plate is such that the thickness change during the charge and discharge process is d max / d min may be 100% to 700%.

[0037] It should be noted that for a "no negative electrode" metal battery, when the battery is at 100% SOC, a metal layer is deposited on the surface of the negative electrode current collector, and in theory, when the battery is at 0% SOC, the metal layer on the surface of the negative electrode current collector should completely disappear. However, in actual situations, when the battery is in a low SOC state, such as 0% SOC, there may still be a small amount of metal deposited irregularly on the negative electrode current collector. The thickness of this residual deposited metal is small, and its impact on the thickness of the negative electrode plate is negligible.

[0038] According to some embodiments of the present application, for a negative electrode plate in which a negative electrode active material is added during the production process and a negative electrode active material layer is formed on the surface of a negative electrode current collector, taking a sodium ion battery as an example, during the charge and discharge process of this negative electrode plate, the generation of sodium dendrites on the surface of the negative electrode active material layer, the intercalation reaction of sodium ions in the negative electrode active material layer, the alloy reaction involving sodium ions, and the expansion of the silicon-containing negative electrode active material in the negative electrode active material layer all cause volume expansion and contraction of the negative electrode plate during the charge and discharge process. The positive electrode plate in the present application can also be applied to a battery containing the above negative electrode plate, and can effectively mitigate stress changes caused by volume changes of the negative electrode plate.

[0039] As can be understood, the positive electrode plate in this application is also applicable to a lithium ion battery system, and those skilled in the art can appropriately adjust the type of positive electrode active material, negative electrode current collector, etc. according to the actual situation, and no further description will be given here.

[0040] According to another aspect of the present application, the present application proposes a method for manufacturing the above-mentioned positive electrode plate, which includes providing a positive electrode current collector, providing a positive electrode slurry, and coating the positive electrode slurry on at least one surface of the positive electrode current collector to form a positive electrode active material layer, thereby having all the features and advantages of the above-mentioned positive electrode plate, which will not be further described herein.

[0041] According to some embodiments of the present application, a positive electrode plate satisfying the above-described porosity requirement can be obtained by a chemical method. Specifically, preparing a positive electrode slurry may include uniformly mixing a positive electrode active material and a sodium supplement additive in a solvent. After forming the positive electrode active material layer, the positive electrode plate and the negative electrode plate may be assembled into a battery and subjected to a chemical conversion treatment. In this step, the residual volatile or semi-residual sodium supplement additive is uniformly mixed with the positive electrode active material. The sodium supplement additive reacts and gases during the chemical conversion treatment of the battery, leaving a pore structure in the positive electrode active material layer, further improving the porosity of the positive electrode active material layer. When a sodium-free and / or low-sodium positive electrode active material is selected, the content of the sodium supplement additive may be appropriately increased so that the energy density of the positive electrode plate meets the battery design requirement. When a typical sodium-containing positive electrode active material is selected, the content of the sodium supplement additive may be appropriately reduced so that the energy density of the positive electrode plate meets the battery design requirement. Those skilled in the art can make a selection according to the actual situation.

[0042] It should be noted that the material types and related parameters of the positive electrode active material and the sodium supplement additive may be determined by referring to some or all of the technical features in the above-described examples. For the parts not described in this embodiment, please refer to the above-described examples and related drawings, and no further description will be given here.

[0043] According to some embodiments of the present application, the method further includes, before coating at least one surface of the positive current collector with the positive electrode slurry, placing sodium foil on the surface of the positive current collector on which the positive electrode slurry is to be coated, thereby further improving the sodium supply effect on the positive electrode plate by the placement of the sodium foil.

[0044] According to some embodiments of the present application, a positive electrode plate that satisfies the above-mentioned porosity requirements can be obtained by a physical method. Specifically, the positive electrode plate is placed under a press roller and subjected to a cold-pressing process. The cold-pressed positive electrode plate is then subjected to a secondary slitting process and then roll-pressed by a hole-making roller before being wound into a sheet. Hole-making nails of different lengths are installed on the hole-making roller, thereby enabling adjustment and control of the porosity of the positive electrode active material layer, increasing the porosity of the positive electrode active material layer, and reducing the cost of battery production. According to some embodiments of the present application, the hole-making roller may include a roller body and hole-making nails distributed on the surface of the roller body, the hole-making nails including at least one row of first hole-making nails and at least one row of second hole-making nails, each row of first hole-making nails being installed adjacent to each row of second hole-making nails, the length of the first hole-making nails being greater than the length of the second hole-making nails, the length of the first hole-making nails being 80% to 90% of the thickness of the active material layer, the length of the second hole-making nails being 40% to 60% of the thickness of the active material layer, the arrangement density of the second hole-making nails being 100% to 200% of the arrangement density of the first hole-making nails, the diameter of the hole-making nails being 100 μm to 800 μm, and the pitch of two adjacent rows of first hole-making nails being 1 to 2 times the length of the first hole-making nails. Specifically, one row of first drilling nails is installed between two adjacent rows of second drilling nails, the pitch between the two adjacent rows of first drilling nails is 1.5 times the length of the first drilling nails, the pitch between the two adjacent rows of second drilling nails is 1.5 times the length of the first drilling nails, the length of the first drilling nails is 85% of the thickness of the positive electrode active material layer and the diameter is 550 μm, the length of the second drilling nails is 50% of the thickness of the positive electrode active material layer and the diameter is 550 μm, and the arrangement density of the second drilling nails is 150% of the arrangement density of the first drilling nails, thereby obtaining a positive electrode active material layer with a porosity within the above range.

[0045] According to yet another aspect of the present application, the present application proposes a battery, comprising: a positive electrode plate; a negative electrode plate; and a separator located between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate is the positive electrode plate described above and / or a positive electrode plate obtained by employing the method described above; the negative electrode plate comprises a negative electrode current collector; and the thickness of the negative electrode plate is d max / d min is 100% to 700%, where d max is the thickness of the negative electrode plate when the battery is at 100% SOC, and d min is the thickness of the negative electrode plate when the battery is at 0% SOC. According to some other embodiments of the present application, the thickness of the negative electrode plate is max / d min is 120% to 400%, so that the battery has a relatively good volume change rate during charging and discharging and a relatively high structural stability.

[0046] According to some embodiments of the present application, the battery shape is not particularly limited, and may be cylindrical, rectangular, or any other shape. FIG. 4 illustrates a rectangular battery 5 as an example. Specifically, referring to FIG. 5, the exterior body may include a case 51 and a top cover assembly 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 may cover the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery 5 may be one or more, and those skilled in the art can select the number according to actual needs.

[0047] According to some embodiments of the present application, a battery may include an exterior body, which is used to package the positive electrode plate, the negative electrode plate, and the electrolyte.

[0048] According to some embodiments of the present application, the exterior body may include a case and a cover plate. Here, the case may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate together form a surrounding accommodating cavity. The case has an opening communicating with the accommodating cavity, and the cover plate can cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly through a winding process or a stacking process. The electrode assembly is packaged in the accommodating cavity. The electrolyte may be an electrolytic solution, which is impregnated into the electrode assembly. The number of electrode assemblies included in the battery may be one or more and can be adjusted according to needs.

[0049] According to some embodiments of the present application, the battery exterior may be a hard case, such as a hard plastic case, an aluminum case, or a steel case. The battery exterior may be a pouch, such as a bag-like pouch. The pouch may be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0050] According to some embodiments of the present application, batteries may be assembled into a battery module, and the number of batteries included in a battery module may be multiple, with the specific number being adjustable according to the application and capacity of the battery module. Referring to FIG. 6 , in a battery module 4, the multiple batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple batteries 5 may be fastened with fasteners. The battery module 4 may further include a housing having an accommodating space, and the multiple batteries 5 are accommodated in this accommodating space. The battery module 4 may further include a housing having an accommodating space, and the multiple secondary batteries 5 are accommodated in this accommodating space. In some embodiments, the battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjustable according to the application and capacity of the battery pack.

[0051] According to some embodiments of the present application, the battery modules may be further assembled into a battery pack. The battery pack may include one or more battery modules, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery pack. FIGS. 7 and 8 show an example battery pack 1. Referring to FIGS. 7 and 8, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 is attached to the lower housing 3 with a lid to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0052] According to a further aspect of the present application, the present application proposes a power consuming device, the power consuming device including the above-described positive electrode plate and / or a positive electrode plate manufactured using the above-described method and / or the above-described battery, the battery being used to provide electrical energy. Specifically, the battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. The power consuming device can select a battery, battery module, or battery pack according to its usage needs.

[0053] 9 illustrates an example power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, according to some embodiments of the present application. A battery pack or a battery module may be employed to meet the high power and high energy density demands of the battery of the power consuming device.

[0054] According to some embodiments of the present application, the power consuming device may be a mobile phone, a tablet computer, a laptop, etc. The device is generally required to be thin and may employ a battery as a power source.

[0055] In this application, regardless of whether words such as "approximately" or "about" are used, all numbers disclosed herein are approximate values. The numerical values ​​of each number may vary by up to 10%, or by a difference that would be considered reasonable by a person skilled in the art, such as 1%, 2%, 3%, 4%, or 5%.

[0056] In describing the present application, it should be understood that the orientations or positional relationships indicated by terms such as "thickness," "top," etc. are orientations or positional relationships shown based on the drawings, and are merely for the convenience and simplification of the description of the present application, and do not indicate or imply that the referenced device or element must have a particular orientation or be configured and operated in a particular orientation, and therefore should not be understood as a limitation on the present application.

[0057] The present invention will be described and illustrated by specific examples below. The following examples are used only to illustrate the present invention and should not be construed as limiting the scope of the present invention. If specific techniques or conditions are not specified in the examples, they will be carried out according to the techniques or conditions described in the literature in the art or according to the product specifications. If the manufacturers of the reagents or instruments used are not specified, they are all ordinary products available commercially.

[0058] Example 1: Positive electrode plate manufacturing: The positive electrode active material Na3V2(PO4)3, the sodium supplement Na2C2O4, the conductive agent acetylene black, and the adhesive polyvinylidene fluoride (PVDF) are dissolved in the solvent N-methylpyrrolidone (NMP) in a weight ratio of 93:0:5:2, and after thoroughly stirring and mixing uniformly, the positive electrode slurry is manufactured. The viscosity of the positive electrode slurry is controlled to 2000mPa·S to 5000mPa·S by adjusting the solvent ratio. The positive electrode slurry was uniformly coated on a 60 μm thick aluminum foil positive electrode current collector, then dried, cold pressed, and slit to obtain a positive electrode plate, and the coating area density was controlled according to the corresponding example below.

[0059] Negative electrode plate manufacturing: Conductive carbon tube dispersion (conductive carbon content 2 wt%) and thickener, methyl cellulose sodium (CMC-Na), were mixed uniformly in a 95:5 weight ratio in an appropriate amount of deionized water solvent system with sufficient stirring. The viscosity of the negative electrode slurry was then controlled to 2000 mPa·S to 8000 mPa·S, and the mixture was coated onto a 60 μm copper foil and dried to obtain a negative electrode plate with a functional coating on both surfaces of the negative electrode current collector.

[0060] Battery manufacturing: A positive electrode plate, a separator, and a negative electrode plate are stacked in this order, and a separator is placed between the positive and negative electrodes to provide isolation. The stack is then wound to obtain an electrode assembly. The electrode assembly is then placed into a designed battery case, an electrolyte is added to the battery case, and the battery is left to stand for 12 hours before undergoing a chemical treatment. The air is vented to negative pressure during the chemical treatment period, and the battery is then packaged to obtain a battery.

[0061] Examples 2 to 8 and Comparative Examples 1 to 4 are identical to Example 1, and differences are specifically shown in Table 1.

[0062] The following performance tests were carried out on the batteries of Examples 1 to 8 and Comparative Examples 1 to 4, and the test methods were as follows.

[0063] 1. Porosity of the positive electrode active material layer: Refer to GB / T 24586-2009 and determine it by the following steps, that is, immerse the positive electrode plate in ethyl methyl carbonate (EMC) to clean it, and use AccuPyc II 1340 instrument to measure it by gas displacement method, and calculate it by the formula: ρ 総 =(V-V0) / V 総 × 100%, where V0 is the true volume, V is the apparent volume, and ρ is the porosity of the positive electrode active material layer. = ρ 総 ×V / (VV 集電体 ), where V 集電体 is the volume of the current collector. See Table 1 for the test results.

[0064] 2. Thickness of the positive electrode plate: D maxThe test involves disassembling the battery when it is at 0% SOC and then using a micrometer to test the thickness of the positive electrode plate. min The test involves disassembling the battery when it is at 100% SOC and then testing the thickness of the positive electrode plate with a micrometer. 100% SOC refers to charging the battery at 1C from 2.5V to 4.3V in a constant temperature environment of 25°C until the current at 4.3V drops to 0.05mA or less. 0% SOC refers to discharging the battery at 1C as close to 0% SOC as possible, then further discharging at 0.04C to the target voltage. After disassembling the battery core, the surface area of ​​the metal deposits on the negative electrode current collector must account for 5% or less of the total area of ​​the disassembled negative electrode current collector. See Table 2 for test results.

[0065] 3. Thickness of negative electrode plate: d max The test involves disassembling the battery when it is at 100% SOC and then using a micrometer to test the thickness of the negative electrode plate; min The test involves disassembling the battery when it is at 0% SOC and then testing the thickness of the negative electrode plate with a micrometer. The test results are shown in Table 2.

[0066] 4. Battery cycle life: In a constant temperature environment of 25°C, the battery was charged from 1.5 to 3.6 V at 1 C up to 4.3 V, and then charged at a constant voltage until the current at 4.3 V fell to 0.05 mA or less. The battery was left to stand for 5 minutes, then discharged at 1 C down to 2.5 V, recording the discharge capacity at this point as D0. The above charge-discharge cycle was repeated until the discharge capacity fell to 80% of D0. The number of cycles the battery had passed was recorded, representing the cycle life at 80% SOH (State of Health). See Table 2 for test results.

[0067] 5. Battery Cycling Pressure: The test battery core was placed in a test fixture, which consisted of three plates, either steel or aluminum. The three plates, battery core, and sensor were arranged in a "plate / battery core / plate sensor / plate" configuration. The distance between the plates was adjusted to adjust the appropriate initial fixture force (the surface pressure was calculated based on the force-bearing area of ​​the battery core, P = F / S). The sensor transmitted specific corresponding expansion force data during the cycles. The maximum expansion force during each cycle was recorded, and the corresponding cycle number at 1 MPa was calculated as the pressure cutoff condition. See Table 2 for test results.

[0068] 6. Compaction density of positive electrode plate: Mass of positive electrode plate per unit area (g / cm 2 ) and thickness (cm) of the positive electrode plate (number of collection points > 14). Here, compaction density = mass of the positive electrode plate per unit area (g / cm 2 ) / thickness of positive electrode plate (cm). See Table 1 for test results.

[0069] [Table 1]

[0070] [Table 2]

[0071] Test results: The thickness of the positive electrode plate in Examples 1 to 8 is D max / D min The 80% SOH cycle number of the batteries in Examples 1 to 8 was relatively high, and all of them were superior to the 80% SOH cycle number of the batteries in Comparative Examples 1 to 4. max / D minBy selecting a battery obtained by assembling a positive electrode plate whose thickness satisfies the requirement of 104.5% to 300%, the thickness of the positive and negative electrodes can be matched, and the volume change of the negative electrode plate during the charge and discharge process can be effectively alleviated, thereby effectively improving the cycle life of the battery.

[0072] The thickness of the positive electrode plate in Examples 1 to 8 is D max / D min The cycle numbers corresponding to the expansion pressure of the battery in Examples 1 to 8 of 1 MPa or higher were all relatively high, and were superior to the cycle numbers corresponding to the expansion pressure of the battery in Comparative Examples 1 to 4 of 1 MPa or higher. max / D min By selecting a battery obtained by assembling a positive electrode plate whose thickness satisfies the requirement of 104.5% to 300%, the surface flatness of the battery is relatively high, and the internal stress of the battery is kept relatively stable during the charge and discharge process, thereby significantly improving the structural stability of the battery.

[0073] Here, the positive electrode active materials in Examples 7 and 8 use sulfide positive electrode active materials, which effectively improve the volume change rate of the positive electrode plate and further improve the expansion resistance of the battery. In Comparative Example 3, the porosity of the positive electrode active material layer was too large, which resulted in relatively poor structural stability of the positive electrode plate and, further, relatively poor structural stability of the battery, resulting in a clear decline in cycle performance.

[0074] In the description of this application, "A and / or B" may include any one of the cases of A alone, B alone, and A and B, where A and B are merely examples, and may be any technical feature connected with "and / or" in this application.

[0075] Unless otherwise explained, all scientific and technical terms used in this application have the same meaning as commonly understood by one skilled in the art to which this application pertains. All patents and publications relating to this application are incorporated herein by reference in their entirety. The terms "comprises" or "includes" are open-ended, i.e., include the content set forth in this application but do not exclude the content of other aspects.

[0076] In the description herein, references to terms such as "one embodiment," "another embodiment," etc., mean that the specific features, structures, materials, or characteristics described in connection with this embodiment are included in at least one embodiment of the present application. In this specification, general expressions using such terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. It should be noted that, unless mutually inconsistent, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described herein. It should also be understood that the terms "first," "second," etc., used herein are for descriptive purposes only and do not indicate or imply relative importance or implicitly indicate the number of the indicated technical features.

[0077] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are illustrative and should not be construed as limitations on the present application, and that those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present application. [Explanation of symbols]

[0078] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: battery, 11: negative electrode current collector, 12: sodium metal layer, 21: positive electrode current collector, 22: positive electrode active material layer, 30: separator, 40: electrolyte, 51: case, 52: electrode assembly, 53: top cover assembly.

Claims

1. A positive electrode plate, a positive electrode current collector; a positive electrode active material layer disposed on at least one surface of the positive electrode current collector and containing a positive electrode active material, the positive electrode active material containing a sodium-containing positive electrode active material; The thickness of the positive electrode plate is D ｍａｘ / D ｍｉｎ is 104.5% to 300%, and after assembling the positive electrode plate and the negative electrode plate into a battery, the thickness of the positive electrode plate when the battery is at 0% SOC is set to D ｍａｘ The thickness of the positive electrode plate when the battery is at 100% SOC is defined as D ｍｉｎ year, Here, the negative electrode plate includes a negative electrode current collector, and when the battery is at 100% SOC, a sodium metal layer is formed on at least one surface of the negative electrode current collector.

2. The positive electrode plate according to claim 1, wherein the porosity of the positive electrode active material layer is 25% to 50%.

3. The positive electrode active material includes a layered oxide, and the layered oxide has the chemical formula Na ｘ M ｙ O ２ wherein 0<x≦4.5 and 0<y≦1; and the M element includes at least one of Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, and preferably, the M element includes at least one of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, and Zn.

4. The positive electrode active material includes a polyanion type compound, a cation element of the polyanion type compound includes at least one of Ni, V, Co, Fe, Mn, and Cu, and an anion of the polyanion type compound includes F － , P.O. ４ ３－ , P ２ O ７ ４－ and (PO ４ ) ２ P ２ O ７ １０－ Preferably, the anion of the polyanionic compound is F － The positive electrode plate according to claim 1 or 2, comprising:

5. The anion of the polyanionic compound is PO ４ ３－ and P ２ O ７ ４－ and wherein the P in the polyanion type compound ２ O ７ ４－ and the aforementioned PO ４ ３－ The molar ratio of the P in the polyanion type compound is 0.1 to 5. ２ O ７ ４－ and the aforementioned PO ４ ３－ The positive electrode plate according to claim 4, wherein the molar ratio of is 0.1 to 3.

6. The positive electrode plate according to any one of claims 1 to 5, wherein the positive electrode active material layer further contains a sodium supplement additive, the mass fraction of the positive electrode active material in the positive electrode active material layer is 50 wt% to 98 wt%, and the mass fraction of the sodium supplement additive in the positive electrode active material layer is 2 wt% to 50 wt%.

7. The sodium supplement additive is Na ２ S, NaN ３ , Na ２ NiO ２ , NaC ６ H ５ O ７ , Na ２ O, Na ２ O ２ , Na ６ CoO ４ , Na ５ FeO ４ , Na ２ C ２ O ４ , Na ２ C ４ O ４ , Na ２ C ３ O ５ , Na ２ C ４ O ６ and Na ２ C ６ O ６ The positive electrode plate of claim 6, comprising at least one of:

8. The thickness of the negative electrode plate is d ｍａｘ / d ｍｉｎ is 100% to 700%, wherein the d ｍａｘ is the thickness of the negative electrode plate when the battery is at 100% SOC, and d ｍｉｎ 8. The positive plate of claim 1, wherein ≈1 / 2 is the thickness of the negative plate when the battery is at 0% SOC.

9. A method for producing the positive electrode plate according to any one of claims 1 to 8, comprising: Providing a positive electrode current collector; providing a positive electrode slurry; and coating the positive electrode slurry on at least one surface of the positive electrode current collector to form a positive electrode active material layer.

10. 10. The method of claim 9, wherein providing the positive electrode slurry comprises uniformly mixing a positive electrode active material and a sodium supplement additive in a solvent, and further comprising, after forming the positive electrode active material layer, assembling the positive electrode plate and the negative electrode plate into a battery and performing a chemical conversion treatment.

11. 11. The method of claim 9 or 10, further comprising, before applying the positive electrode slurry to at least one surface of the positive electrode current collector, placing sodium foil on a surface of the positive electrode current collector that is to be coated with the positive electrode slurry.

12. A battery comprising a positive electrode plate, a negative electrode plate, and a separator located between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate is the positive electrode plate according to any one of claims 1 to 8 and / or a positive electrode plate obtained by employing the method according to any one of claims 9 to 11; The negative electrode plate includes a negative electrode current collector, and the thickness of the negative electrode plate is d ｍａｘ / d ｍｉｎ is 100% to 700%, wherein the d ｍａｘ is the thickness of the negative electrode plate when the battery is at 100% SOC, and d ｍｉｎ is the thickness of the negative electrode plate when the battery is at 0% SOC.

13. A power consumption device comprising a positive electrode plate according to any one of claims 1 to 8, and / or a positive electrode plate produced by employing a method according to any one of claims 9 to 11, and / or a battery according to claim 12.

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