Sodium-ion batteries, batteries and power consumption devices

Abstract

This application provides a sodium-ion battery, a battery and a power consumption device. The sodium-ion battery includes a negative electrode plate and a positive electrode plate containing a positive electrode active material, the negative electrode plate includes a negative electrode current collector and a sodium metal layer placed on at least one surface of the negative electrode current collector, the slope of the state of charge (SOC) - open-circuit voltage (OCV) curve of the sodium-ion battery is k, and the state of charge (SOC) - open-circuit voltage (OCV) curve of the sodium-ion battery satisfies cumulative SOC ≥ 20% and k ≥ 5mV / 1%SOC.

Description

Technical Field

[0001] This application relates to sodium ion batteries, batteries and power-consuming devices.

Background Art

[0002] Sodium ion batteries have characteristics such as high capacity and long life, and are thus widely applied to electronic devices, such as mobile phones, notebook computers, battery vehicles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools.

[0003] As the application range of batteries becomes increasingly wide, the requirements for the performance of sodium ion batteries are also gradually becoming stricter. Since sodium ion batteries have almost no voltage change at the negative electrode, they are disadvantageous for correcting the state of charge, and thereby disadvantageous for the control of the battery management system.

Summary of the Invention

[0004] This application has been made in view of the above problems, and its object is to provide a sodium ion battery, a battery and a power-consuming device.

[0005] The first aspect of this application provides a sodium ion battery, the sodium ion battery includes a negative electrode plate and a positive electrode plate containing a positive electrode active material, the negative electrode plate includes a negative electrode current collector and a sodium metal layer provided on at least one surface of the negative electrode current collector, the slope of the state of charge SOC-open circuit voltage OCV curve of the sodium ion battery is k, and the state of charge SOC-open circuit voltage OCV curve of the sodium ion battery satisfies cumulative SOC≥20% and k≥5 mV / 1%SOC.

[0006] Thereby, when the sodium ion battery of the embodiment of the present application satisfies the above range, within 0 to 100% SOC, at least a cumulative 20% SOC has a significant plateau change, that is, the SOC-OCV curve has a significant slope change and has k≧5 mV / 1% SOC, which is advantageous for the control of the battery management system BMS.

[0007] In some embodiments, the state of charge SOC-open circuit voltage OCV curve of the sodium ion battery satisfies 90%≦SOC≦100% and k≧5 mV / 1% SOC.

[0008] In some embodiments, the state of charge SOC-open circuit voltage OCV curve of the sodium ion battery satisfies 25%≦SOC≦50% and k≧5 mV / 1% SOC.

[0009] In some embodiments, the positive electrode plate contains a positive electrode active material, and the positive electrode active material contains at least one of a layered oxide, a sodium-containing polyanion-type compound, and a modified compound thereof. By using the combination of the above two types of materials in the embodiments of the present application, the state of charge SOC-open circuit voltage OCV curve of the sodium ion battery can be adjusted, which is advantageous for more accurately controlling the battery management system BMS.

[0010] In some embodiments, the layered oxide contains one or more of a compound with a molecular formula of Na x M y O2 and its modified compounds, where 0<x≦4.5, 0<y≦1, and M is selected from one or more of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce. Further optionally, M is selected from one or more of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, and Zn.

[0011] In some embodiments, the layered oxide is NaFeO2, NaTiO2, NaMnO2, Na2NiO2, Na 2 / 3 [Ni1 / 3 Mn 2 / 3 O2, Na 2 / 3 [Cu 1 / 3 Mn 2 / 3 O2, Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 O2, Na 2 / 3 [Co 2 / 3 Mn 1 / 3 O2, Na 7 / 9 [Cu 2 / 9 Fe 1 / 9 Mn 2 / 3 O2 contains one or more of them.

[0012] In some embodiments, the anion of the polyanion-type compound is PO4 3- , P2O7 4- , (PO4)2P2O7 10- , (SO4)2 4- and (SO4)3 6- contains one or more of them, and further optionally, the anion of the polyanion-type compound further contains F - .

[0013] In some embodiments, the polyanion-type compound contains cations of one or more elements selected from the group consisting of Ni, V, Co, Fe, Mn, Ti, Cr, Zn, and Cu.

[0014] In some embodiments, the polyanion-type compound contains one or more of NaCoPO4, NaMnPO4, Na3V2(PO4)3, NaCoPO4F, Na2CoP2O7, Na2FeP2O7, Na2MnP2O7, Na4Co3(PO4)2P2O7, Na4Fe3(PO4)2P2O7, Na4Mn3(PO4)2P2O7, and Na2Fe(SO4) 2、 Na2Fe2(SO4)3.

[0015] In some embodiments, based on the total molar amount of the anion of the polyanion-type compound, the molar percentage content of PO4 3- is denoted as A mol %, and the molar percentage content of P2O7 4- is denoted as B molDenoted as %, the polyanionic compound satisfies 0.1 ≤ A / B ≤ 5.0, and selectively satisfies 0.1 ≤ A / B ≤ 3.0.

[0016] In some embodiments, the mass percentage content of the layered oxide is Cwt%, based on the total mass of the layered oxide and the polyanionic compound, and 0 <C≦70である。

[0017] A second aspect of this application further provides a battery comprising a sodium-ion battery as described in any embodiment of the first aspect of this application.

[0018] A third aspect of this application further provides a power consumption device including a battery as described in the second aspect of this application. [Brief explanation of the drawing]

[0019] To more clearly explain the technical concept of the embodiments of this application, the following briefly introduces the drawings that may be used in the embodiments of this application. It is obvious that the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Figure 1] This is a schematic diagram of one embodiment of the secondary battery of this application. [Figure 2] Figure 1 is a schematic diagram of an exploded view of an embodiment of a secondary battery. [Figure 3] This is a schematic diagram of one embodiment of the battery module of this application. [Figure 4] This is a schematic diagram of one embodiment of the battery pack of this application. [Figure 5] Figure 4 is a schematic exploded view of an embodiment of the battery pack shown. [Figure 6] This is a schematic diagram of one embodiment including a power consumption device that uses a secondary battery of the present application as a power source. [Figure 7] These are the open-circuit voltage (OCV) - state of charge (SOC) curves for sodium-ion batteries in Comparative Example 1 and Example 1.

[0020] The drawings are not always drawn to actual scale. [Modes for carrying out the invention]

[0021] The following describes in detail embodiments specifically disclosing the sodium-ion battery, battery and power consumption device of this application. However, unnecessary details may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0022] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also conceivable. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are all conceivable. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviated expression for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have already been listed in this specification, and "0-5" is simply a shortened representation of combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0024] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if a method mentioned may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0025] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may represent an open or closed configuration. For example, the terms “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

[0026] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and both A and B are true (or exist).

[0027] In this application, the terms "multiple" and "multiple types" refer to two or more.

[0028] To characterize the state of a battery, its capacity is generally reflected by testing its state of charge (SOC). When no charging is taking place, the battery's capacity can be considered to be A0, corresponding to 0%SOC. When the battery is fully charged, it can be considered to have reached its rated capacity A, corresponding to 100%SOC. During the charging process, if the battery's capacity is x%(A-A0), it corresponds to x%SOC, where x% is a number between 0 and 100. For example, if x is 70, the battery has been charged until its capacity reaches 70%(A-A0), corresponding to 70%SOC.

[0029] In related technologies, the open-circuit voltage method is often used to correct the battery's charge state. A detection unit is used to test the battery's open-circuit voltage (OCV). The detection unit transmits this open-circuit voltage OCV to the battery management system (BMS). The BMS obtains the battery's charge state based on the battery's SOC-OCV curve. Based on this charge state and the previously acquired charge state, it obtains the first charge state change of the battery. Simultaneously, the BMS obtains the current in the battery circuit and obtains the second charge state change of the battery by ampere-hour integration. Finally, the BMS corrects the second charge state change obtained by ampere-hour integration using the first charge state change obtained by the open-circuit voltage method to obtain the battery's charge state.

[0030] However, in related technologies, the negative electrode plate of a sodium-ion battery includes a negative electrode current collector and a sodium metal layer. During the charge-discharge process, the sodium metal layer experiences almost no voltage change, and the positive electrode plate of a sodium-ion battery may exhibit full plateau characteristics. Therefore, it is difficult to determine the negative electrode SOC state and the full battery SOC state using the SOC-OCV curve, which makes closed-loop correction impossible and is disadvantageous for controlling the battery management system (BMS).

[0031] To address the above problem, the inventor has found that by improving the positive electrode active material, a constant slope change can be introduced into the SOC-OCV curve, which is advantageous for controlling the battery management system (BMS).

[0032] Sodium-ion battery According to a first aspect, the present application provides a sodium-ion battery, the sodium-ion battery comprising a negative electrode plate and a positive electrode plate containing a positive electrode active material, the negative electrode plate comprising a negative electrode current collector and a sodium metal layer provided on at least one surface of the negative electrode current collector, the slope of the state of charge (SOC) - open-circuit voltage (OCV) curve of the sodium-ion battery being k, and the state of charge (SOC) - open-circuit voltage (OCV) curve of the sodium-ion battery satisfying cumulative SOC ≥ 20% and k ≥ 5mV / 1%SOC.

[0033] The sodium metal layer of the negative electrode plate may be a sodium metal sheet installed on the negative electrode current collector, and the sodium metal sheet may be installed on one surface or two surfaces of the negative electrode current collector. Alternatively, the sodium metal layer may be sodium metal deposited on the negative electrode current collector during the charging process.

[0034] The positive electrode active material in the positive electrode plate has a tilt change characteristic, and the positive electrode active material is used in combination with the negative electrode plate, thereby exhibiting an OCV change characteristic during the charging process.

[0035] When the sodium-ion battery of the embodiment of this application satisfies the above range, at least 20% cumulative SOC has a significant plateau change within 0 to 100% SOC, i.e., the SOC-OCV curve has a significant slope change and k ≥ 5mV / 1% SOC, which is advantageous for control of the battery management system (BMS).

[0036] The following is one embodiment of the test method for the State of Charge (SOC) - Open-Circuit Voltage (OCV) curve of the present application, and includes the following steps: S101: To fully charge the sodium-ion battery, the sodium-ion battery is charged at a constant current and constant voltage until it reaches the nominal upper cutoff voltage of the sodium-ion battery. S102: Allow a fully charged sodium-ion battery to stand for 2 hours to facilitate sufficient permeation of the electrolyte between the separator and active material, and to stabilize the voltage of the sodium-ion battery. S103: The sodium-ion battery was discharged at a discharge rate of 0.33C down to its lower cutoff voltage, and the actual capacity C0 released from the sodium-ion battery was tested and obtained. The actual capacity C0 released is the actual capacity of the sodium-ion battery. S104: Allow the discharged sodium-ion battery to stand for 2 hours to facilitate sufficient permeation of the electrolyte between the separator and active material, and to stabilize the voltage of the sodium-ion battery. S105: Use 0.04C0 to constantly charge the sodium-ion battery and obtain a capacity C1. S106: Using C1 as the denominator, convert the capacitance-open-circuit voltage curve to a charge state-of-charge (SOC)-open-circuit voltage (OCV) curve.

[0037] Furthermore, the nominal current can be freely selected according to the battery capacity. For example, if the battery capacity is 50Ah, the nominal current may be 50A, and if the battery capacity is 100Ah, the nominal current may be 100A.

[0038] In the embodiments of this application, cumulative SOC is the interval difference of the x-coordinate. For example, if the interval range of the x-coordinate SOC includes (10% to 50%), the cumulative SOC is 50% - 10% = 40%, i.e., the cumulative SOC is 40%. Also, for example, if the interval range of the x-coordinate SOC includes (10% to 50%) and (70% to 80%), the cumulative SOC is (50% - 10%) + (80% - 70%) = 50%, i.e., the cumulative SOC is 50%.

[0039] The slope k represents the degree to which the tangent line of a curve is inclined with respect to the horizontal axis. It can be expressed using the ratio of the difference in the vertical coordinates of two points to the difference in the horizontal coordinates. For example, k = 5mV / 1%SOC means that the interval difference value of the horizontal coordinate is 1%SOC and the interval difference value of the vertical coordinate is 5mV.

[0040] The cumulative SOC being 40% and k ≥ 5mV / 1%SOC indicates that within the interval difference of 40%SOC, the slope k of the curve is always 5mV / 1%SOC or greater.

[0041] For example, cumulative SOC ≥ 20% and k ≥ 5mV / 1%SOC, or cumulative SOC ≥ 35% and k ≥ 5mV / 1%SOC, or cumulative SOC ≥ 40% and k ≥ 5mV / 1%SOC, or cumulative SOC ≥ 45% and k ≥ 5mV / 1%SOC.

[0042] In some embodiments, the SOC-OCV curve of a sodium-ion battery satisfies 90% ≤ SOC ≤ 100% and k ≥ 5mV / 1%SOC, where 90% ≤ SOC ≤ 100% means that within the interval range of 90% to 100% of the x-coordinate SOC, the slope of the curve is 5mV / 1%SOC or greater. When the SOC-OCV curve of a sodium-ion battery satisfies the above range, the risk of overcharging of the sodium-ion battery can be reduced to some extent, and it is more advantageous to control full charging.

[0043] In some embodiments, the SOC-OCV curve of a sodium-ion battery satisfies 25% ≤ SOC ≤ 50% and k ≥ 5mV / 1%SOC, where 25% ≤ SOC ≤ 50% means that within the interval range of 25% to 50% of the horizontal coordinate SOC, the slope of the curve is 5mV / 1%SOC or greater in all cases. When the SOC-OCV curve of a sodium-ion battery satisfies the above range, it is advantageous for detecting the stepping point, and corrections are made to SOC and SOH.

[0044] [Positive electrode plate] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0045] The positive electrode film layer may be provided on one surface of the positive electrode current collector or on two surfaces of the positive electrode current collector.

[0046] In the sodium ion battery according to the embodiment of the present application, when the positive electrode active material satisfies at least one of the following conditions, the slope change characteristics of the SOC-OCV curve of the positive electrode active material are more significant, which is advantageous for the control of the battery management system BMS.

[0047] In some embodiments, the positive electrode active material includes a layered oxide. Optionally, the layered oxide has a molecular formula of Na x M y O2 and includes one or more of its modified compounds, where 0 < x ≤ 2.1, 0 < y ≤ 2.1, M is selected from one or more of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, and further optionally, M is selected from one or more of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, and Zn.

[0048] Exemplarily, the layered oxide includes one or more of NaFeO2, NaTiO2, NaMnO2, Na2NiO2, Na 2 / 3 [Ni 1 / 3 Mn 2 / 3 O2, Na 2 / 3 [Ni 1 / 3 Mn 1 / 3 Fe 1 / 3 O2, Na 2 / 3 [Cu 1 / 3 Mn 2 / 3 O2, Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 O2, Na 2 / 3 [Co 2 / 3 Mn 1 / 3 O2, Na 7 / 9 [Cu 2 / 9 Fe 1 / 9 Mn 2 / 3 O2.

[0049] In some embodiments, the positive electrode active material further comprises a sodium-containing polyanionic compound and a modified compound thereof, wherein the polyanionic compound has various types, such as phosphates, pyrophosphates, mixed polyanionic compounds, and sulfates.

[0050] In some embodiments, the cations of the polyanionic compound may further include, in addition to sodium ions, cations of one or more elements from the group consisting of Ni, V, Co, Fe, Mn, Ti, Cr, Zn, and Cu.

[0051] In some embodiments, the anion of the polyanionic compound is PO4 3- P2O7 4- (PO4)2P2O7 10- , (SO4)2 4- (SO4)3 6- This includes one or more of the following.

[0052] In some embodiments, the anion of the polyanionic compound is F - It also includes.

[0053] In some embodiments, the total molar amount of anions in the polyanionic compound is used as the basis for PO4 3- The molar percentage content is A mol It is written as % and P2O7 4- The molar percentage content is B mol Denoted as a percentage, polyanionic compounds satisfy 0.1 ≤ A / B ≤ 5.0, and selectively satisfy 0.1 ≤ A / B ≤ 3.0. Specifically, polyanionic compounds may include a mixture of phosphate and pyrophosphate, or polyanionic compounds may include a mixed polyanion. Exemplarily, A / B may be in the range of 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, or any two of the above values.

[0054] For example, phosphates include one or more of NaCoPO4, NaMnPO4, Na3V2(PO4)3, and NaCoPO4F.

[0055] Exemplarily, the pyrophosphate contains one or more of Na2CoP2O7, Na2FeP2O7, and Na2MnP2O7.

[0056] Exemplarily, the mixed polyanion-type compound contains one or more of Na4Co3(PO4)2P2O7, Na4Fe3(PO4)2P2O7, and Na4Mn3(PO4)2P2O7.

[0057] Exemplarily, the sulfate contains at least one of Na2Fe(SO4)2 and Na2Fe2(SO4)3.

[0058] In some embodiments, the positive electrode active material may contain a layered oxide and a polyanion-type compound. Based on the mass of the positive electrode active material, the mass percentage content of the layered oxide is Cwt%, where 0 < C ≤ 70. Exemplarily, the mass percentage content Cwt% of the layered oxide is 1 wt %, 2 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt %, 25 wt %, 30wt%, 35 wt %, 40 wt %, 45 wt %, 50 wt %, 60 wt %, 70 wt % or may be a range consisting of any two of the above numerical values.

[0059] Assuming that the positive electrode active material conforms to the above conditions, the modified compound of the embodiment of this application includes a surface coating modified compound and / or a doping modified compound, wherein the surface coating modified compound may have a coating layer applied to at least a portion of the surface of the material particles, and the coating layer may include at least one of a carbon layer, an oxide layer, an inorganic salt layer, and a conductive polymer layer, and the cycle performance of the sodium-ion battery can be improved by surface coating modification. The doping modified compound may have at least one of elements such as Li, Zn, and Cu added to the material, and the structural stability of the sodium-ion battery can be improved by doping modification.

[0060] In some embodiments, the positive electrode film layer further selectively comprises a positive electrode conductive agent. Embodiments of this application are not particularly limited to the type of positive electrode conductive agent, and for example, the positive electrode conductive agent comprises at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the positive electrode conductive agent is ≤5 wt% based on the mass of the positive electrode film layer.

[0061] In some embodiments, the positive electrode film layer optionally further comprises a positive electrode adhesive. The embodiments of this application are not particularly limited to the type of positive electrode adhesive, and for example, the positive electrode adhesive may comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins. In some embodiments, the mass percentage content of the positive electrode adhesive is ≤5 wt% based on the mass of the positive electrode film layer.

[0062] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. Aluminum foil can be used as an example of a metal foil sheet. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. For example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0063] The positive electrode film layer is generally obtained by coating a positive electrode slurry onto a positive electrode current collector, drying it, and then cold pressing it. The positive electrode slurry is generally formed by dispersing a positive electrode active material, a selective conductive agent, a selective adhesive, and other selective auxiliary agents in a solvent and stirring them uniformly.

[0064] [Negative electrode plate] In some embodiments, the negative electrode plate includes a negative electrode current collector. During the charging process, sodium ions gain electrons on the surface of the negative electrode current collector, forming a sodium metal layer.

[0065] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. Examples of metal foil sheets include aluminum foil or copper foil. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys. For example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0066] Furthermore, the negative electrode plate further includes a conductive layer placed on the negative electrode current collector, and the conductive layer includes a negative electrode conductive agent. For example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0067] In some other embodiments, the negative electrode plate includes a negative electrode current collector and a sodium metal sheet placed on at least one surface of the negative electrode current collector. For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the sodium metal sheet is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0068] The material of the negative electrode current collector is as described above and will not be explained further here.

[0069] In some embodiments, the negative electrode film layer further selectively comprises a negative electrode conductive agent. The embodiments of this application are not particularly limited to the type of negative electrode conductive agent, and for example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the negative electrode conductive agent is ≤5 wt% based on the total weight of the negative electrode film layer.

[0070] In some embodiments, the negative electrode film layer further selectively includes a negative electrode adhesive. The embodiments of this application are not particularly limited to the type of negative electrode adhesive, and for example, the negative electrode adhesive may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic acid resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage content of the negative electrode adhesive is ≤5 wt% based on the total weight of the negative electrode film layer.

[0071] In some embodiments, the negative electrode film layer may further selectively contain other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, etc. In some embodiments, the mass percentage content of the other additives is ≤2 wt% based on the total weight of the negative electrode film layer.

[0072] The negative electrode film layer is generally obtained by coating a negative electrode slurry onto a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, a selective conductive agent, a selective adhesive, and other selective auxiliary agents in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0073] [Electrolyte] During the charging and discharging process of a battery cell, sodium reciprocates between the positive and negative electrodes, undergoing absorption and release, while the electrolyte plays a role in conducting active ions between the positive and negative electrodes. The embodiments of this application are not particularly limited to the type of electrolyte and can be selected according to actual needs.

[0074] The electrolyte solution comprises an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.

[0075] For example, the electrolyte salt may include at least one of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorobis(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP).

[0076] For example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0077] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and may further include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature power performance.

[0078] [Separator] In some embodiments, the battery cell further includes a separator. Embodiments of this application are not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0079] In some embodiments, the separator material may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0080] In some embodiments, the positive electrode plate, negative electrode plate, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0081] This application does not particularly limit the shape of the battery cell, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a rectangular battery cell 5 as an example.

[0082] In some embodiments, as shown in Figures 1 and 2, the casing may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround and form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 is used to cover the opening in order to seal the housing cavity. The positive electrode plate, negative electrode plate and separator can be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged in the housing cavity. The electrolyte is infused into the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 may be one or more and can be adjusted according to the demand.

[0083] The method for manufacturing a battery cell in the embodiments of this application is known. In some embodiments, a battery cell may be formed by assembling a positive electrode plate, a separator, a negative electrode plate, and an electrolyte. For example, an electrode assembly may be formed by a winding process or a lamination process using a positive electrode plate, a separator, and a negative electrode plate, the electrode assembly may be placed in an outer casing, the electrolyte may be injected after drying, and a battery cell may be obtained through processes such as vacuum packaging, standing, chemical conversion, and shaping.

[0084] In some embodiments of this application, the battery cells according to this application may be assembled into a battery module, and the number of battery cells included in the battery module may be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0085] Figure 3 is a schematic diagram of an example battery module 4. As shown in Figure 3, in the battery module 4, the multiple battery cells 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple battery cells 5 may be fixed together with fasteners.

[0086] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of battery cells 5 are housed.

[0087] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0088] Figures 4 and 5 are schematic diagrams of an example battery pack 1. As shown in Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed inside the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 covering the lower housing 3 and used to form a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0089] The battery of the embodiment of this application may further include one or more battery cells, and if the battery includes multiple battery cells, the battery may also include a battery module or a battery pack.

[0090] power consumption equipment Embodiments of this application further provide a power consumption device comprising at least one of the battery cells, battery modules, and battery packs of this application. The battery cells, battery modules, and battery packs may be used as a power source for the power consumption device or as energy storage units for the power consumption device. The power consumption device may be, 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.

[0091] The power consumption device may select battery cells, battery modules, or battery packs according to its usage needs.

[0092] Figure 6 is a schematic diagram of an example power consumption device. This power consumption device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the demand for high output and high energy density of this power consumption device, a battery pack 1 or battery module may be used. Another example of a power consumption device may be a mobile phone, a tablet PC, a laptop computer, etc. This power consumption device is generally required to be thin, and a battery cell may be used as the power source.

[0093] Examples The embodiments described below are illustrative and intended to interpret this application and should not be construed as limitations thereto. Unless otherwise specified in the embodiments, any specific techniques or conditions are provided in accordance with the techniques, conditions, or product specifications described in the literature within the art. Unless otherwise specified, the reagents or equipment used are all commonly available commercial products.

[0094] Example 1 1. Manufacturing of positive electrode plates: A 12μm thick aluminum foil was used as the positive electrode current collector.

[0095] Positive electrode active material (50 wt% layered sodium oxide) 2 / 3 [Ni 1 / 3 Mn 1 / 3 Fe 1 / 3 A positive electrode slurry was prepared in N-methylpyrrolidone (NMP) by mixing O2, 50 wt% of the polyanionic compound Na3V2(PO4)3), the conductive agent Super P, and the adhesive polyvinylidene fluoride in a mass ratio of 96:2:2. The positive electrode slurry was applied to aluminum foil current collectors, dried at 85°C, cold-pressed, trimmed, cut, and striped, and then dried under vacuum conditions at 85°C for 4 hours to produce a positive electrode plate.

[0096] 2. Manufacturing of the negative electrode plate: A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0097] 3. Manufacturing of electrolyte In an environment with a water content of less than 10 ppm, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether, which are non-aqueous organic solvents, were mixed in a volume ratio of 1:1 to obtain an electrolyte solvent. Subsequently, the solvent was mixed with sodium hexafluorophosphate, which is the sodium salt of the electrolyte, and this mixture was then prepared to create an electrolyte with a sodium salt concentration of 1 mol / L.

[0098] 4. Manufacturing of sodium-ion batteries A 16 μm polyethylene film (PE) was used as a separator. The positive electrode plate, separator, and negative electrode plate were stacked in order, with the separator positioned between the positive and negative electrode plates to provide isolation. The assembly was then wound up to obtain an electrode assembly, placed in an outer casing, dried, and then injected with electrolyte. After processes such as vacuum packaging, standing, chemical formation, and shaping, a sodium-ion battery (a pouch sodium-ion battery with a thickness of 4.0 mm, a width of 60 mm, and a length of 140 mm) was obtained.

[0099] Comparative Example 1 A sodium-ion battery was manufactured using the same method as in Example 1, the only difference from Example 1 being that the positive electrode active material in Comparative Example 1 is Na3V2(PO4)3.

[0100] The parameters for the examples and comparative examples are as shown in Table 1.

[0101] Test method 1. Testing of elemental content in positive electrode plates. The carbon, metal, and other nonmetallic element content was determined by obtaining inductively coupled plasma atomic emission spectroscopy (ICP) using an Agilent ICP-OES730, and then calculating the carbon, metal, and other nonmetallic element content from the ICP results.

[0102] 2, SOC-OCV curve S101: Charge the sodium-ion batteries manufactured in the examples and comparative examples at a constant current and constant voltage until the sodium-ion batteries are fully charged and the nominal upper cutoff voltage of the sodium-ion batteries is reached. S102: Allow a fully charged sodium-ion battery to stand for 2 hours to facilitate sufficient permeation of the electrolyte between the separator and active material, and to stabilize the voltage of the sodium-ion battery. S103: The sodium-ion battery was discharged at a discharge rate of 0.33C down to its lower cutoff voltage, and the actual capacity C0 released from the sodium-ion battery was tested and obtained. The actual capacity C0 released is the actual capacity of the sodium-ion battery. S104: Allow the discharged sodium-ion battery to stand for 2 hours to facilitate sufficient permeation of the electrolyte between the separator and active material, and to stabilize the voltage of the sodium-ion battery. S105: Use 0.04C0 to constantly charge the sodium-ion battery and obtain a capacity C1. S106: Use C as the denominator to convert the capacitance-open-circuit voltage curve to a charge state-of-charge (SOC)-open-circuit voltage (OCV) curve.

[0103] Test results The test results are shown in Table 1.

[0104] [Table 1]

[0105] As can be seen from Figure 7, Figure 7 shows the open-circuit voltage OCV-state of charge (SOC) curves for Comparative Example 1 and Example 1. As can be seen from these curves and Table 1, the OCV-SOC curve of the positive electrode active material in Example 1 shows a significant change in slope compared to Comparative Example 1, which is advantageous for controlling the battery management system (BMS).

[0106] The positive electrode active material of the embodiment of this application is advantageous for accurately controlling the battery management system (BMS) when it satisfies 90% ≤ SOC ≤ 100%, k ≥ 5mV / 1%SOC, and / or 25% ≤ SOC ≤ 50%, k ≥ 5mV / 1%SOC.

[0107] Embodiments of this application adjust the type of positive electrode active material, for example, the anion of the polyanionic active material is PO4 3- and / or (PO4)2P2O7 10- By adjusting the cations (non-sodium ions) of the polyanion active material to other cations, such as Ni, V, Co, etc., the OCV-SOC curve of the entire positive electrode active material exhibits a significant change in slope, which is advantageous for controlling the battery management system (BMS). Embodiments of this application make it possible to give the OCV-SOC curve of the entire positive electrode active material a significant change in slope by adjusting the type of layered oxide, for example, by adjusting the cations of the layered oxide to Ti, V, Cr, Co, etc., which is advantageous for controlling the battery management system (BMS). Of course, this application also allows for adjusting the trend of change in the OCV-SOC curve by adjusting the molar ratio of different anions and / or the molar ratio of different cations.

[0108] The embodiments of this application further adjust the mass ratio of the layered oxide and the polyanionic compound to adjust the trend of change in the OCV-SOC curve of the entire positive electrode active material, thereby enabling more precise control of the battery management system (BMS).

[0109] While this application has been written with reference to preferred embodiments, various modifications are possible and components can be replaced with equivalents, without departing from the scope of this application. In particular, unless there is a structural conflict, each technical feature referred to in each embodiment can be combined in any way. This application is not limited to any specific embodiment disclosed herein, but includes all technical ideas that fall within the scope of the claims. [Explanation of Symbols]

[0110] 1: Battery pack, 2: Upper casing, 3: Lower casing, 4: Battery module, 5: Battery cell, 51: Case, 52: Electrode assembly, 53. Cover plate, 6: Power consumption device.

Claims

1. A sodium-ion battery comprising a negative electrode plate and a positive electrode plate containing a positive electrode active material, wherein the negative electrode plate comprises a negative electrode current collector and a sodium metal layer placed on at least one surface of the negative electrode current collector, The sodium-ion battery is such that the slope of the charge state-of-charge (SOC) - open-circuit voltage (OCV) curve is k, and the charge state-of-charge (SOC) - open-circuit voltage (OCV) curve satisfies cumulative SOC ≥ 20% and k ≥ 5mV / 1% SOC.

2. The sodium-ion battery according to claim 1, wherein the charge state-of-octane (SOC) - open-circuit voltage (OCV) curve of the sodium-ion battery satisfies 90% ≤ SOC ≤ 100%, k ≥ 5 mV / 1% SOC, and / or 25% ≤ SOC ≤ 50%, k ≥ 5 mV / 1% SOC.

3. The positive electrode plate comprises a positive electrode active material, the positive electrode active material comprising at least one of a layered oxide, a sodium-containing polyanionic compound, and a modified compound thereof. Selectively, the layered oxide has a molecular formula of Na ｘ M ｙ O ２ The compound comprises one or more of the compound and its modified compounds, where 0 < x ≤ 4.5 and 0 < y ≤ 1, and M is selected from one or more of Ti, V, Cr, Fe, Co, Mn, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce, and more selectively, M is selected from one or more of Ti, V, Cr, Fe, Co, Mn, Ni, Cu and Zn. Optionally, the anion of the polyanionic compound is PO ４ ３－ , P ２ O ７ ４－ , (PO ４ ), ２ P ２ O ７ １０－ , (SO ４ ), ２ ４－ and (SO ４ ), ３ ６－ one or more of which are included, and further optionally, the anion of the polyanionic compound further includes F － . The sodium ion battery according to claim 1 or 2.

4. The aforementioned layered oxide is NaFeO ２ NaTiO ２ NaMnO ２ Na ２ NiO ２ Na ２／３ [Ni １／３ Mn ２／３ ]O ２ Na ２／３ [Cu １／３ Mn ２／３ ]O ２ Na ２／３ [Fe １／２ Mn １／２ ]O ２ Na ２／３ [Co ２／３ Mn １／３ ]O ２ Na ７／９ [Cu ２／９ Fe １／９ Mn ２／３ ]O ２ A sodium-ion battery according to claim 3, comprising one or more of the above.

5. The sodium-ion battery according to claim 3 or 4, wherein the polyanionic compound comprises a cation of one or more elements from the group consisting of Ni, V, Co, Fe, Mn, Ti, Cr, Zn, and Cu.

6. The aforementioned polyanionic compound is NaCoPO ４ NaMnPO ４ Na ３ V ２ (PO ４ ) ３ NaCoPO ４ F, Na ２ CoP ２ O ７ Na ２ FeP ２ O ７ Na ２ MnP ２ O ７ Na ４ Co ３ (PO ４ ) ２ P ２ O ７ Na ４ Fe ３ (PO ４ ) ２ P ２ O ７ Na ４ Mn ３ (PO ４ ) ２ P ２ O ７ and Na ２ Fe(SO ４ ) ２、 Na ２ Fe ２ (SO ４ ) ３ A sodium-ion battery according to any one of claims 3 to 5, comprising one or more of the above.

7. Based on the total molar amount of the anions of the polyanion-type compound, the molar percentage content of PO ４ ３－ is denoted as A ｍｏｌ %, and the molar percentage content of P ２ O ７ ４－ is denoted as B ｍｏｌ %, and the polyanion-type compound satisfies 0.1 ≦ A / B ≦ 5.0, and optionally, satisfies 0.1 ≦ A / B ≦ 3.0, the sodium-ion battery according to any one of claims 3 to 6.

8. A sodium-ion battery according to any one of claims 3 to 7, wherein the mass percentage content of the layered oxide is Cwt%, based on the total mass of the layered oxide and the polyanionic compound, and 0 < C ≤ 70.

9. A battery comprising a sodium-ion battery according to any one of claims 1 to 8.

10. A power consumption device including the battery described in claim 9.

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