CN116789191B

CN116789191B - Sodium supplementing material, preparation method thereof, positive electrode plate, electrode assembly, battery and electricity utilization device

Info

Publication number: CN116789191B
Application number: CN202310914266.6A
Authority: CN
Inventors: 李静如; 赵子萌; 王世冠; 朱映华; 林宇倩; 徐熙烨; 史松君; 来佑磊
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-07-25
Filing date: 2023-07-25
Publication date: 2024-01-12
Anticipated expiration: 2043-07-25
Also published as: CN116789191A

Abstract

The invention relates to the technical field of batteries, in particular to a sodium supplementing material and a preparation method thereof, an anode plate, an electrode assembly, a battery and an electric device. The chemical formula of the sodium supplementing material comprises Na _x M1O _4‑ _y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S. By adopting M2 element to replace part of lattice oxygen, the structural stability of the sodium supplementing material can be improved, and the oxygen release in the sodium removing process can be reduced, so that the performance of the battery is improved.

Description

Sodium supplementing material, preparation method thereof, positive electrode plate, electrode assembly, battery and electricity utilization device

Technical Field

The invention relates to the technical field of batteries, in particular to a sodium supplementing material and a preparation method thereof, an anode plate, an electrode assembly, a battery and an electric device.

Background

Sodium secondary batteries have great development prospects in the field of large-scale energy storage due to the fact that sodium element reserves are abundant.

There is a problem of sodium loss during the cycling of the sodium secondary battery.

Disclosure of Invention

The invention mainly aims to provide a sodium supplementing material which aims to improve the performance of a battery.

In order to achieve the above object, the present invention provides a sodium supplementing material, the chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S.

In the sodium supplementing process, the lattice oxygen can be removed and react with the electrolyte to generate oxygen. To alleviate the problem of gassing and improve the performance of the battery, the chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, M2 comprises at least one of F, N, P, S, the structural stability of the sodium supplementing material can be improved by adopting M2 element to replace part of lattice oxygen, and oxygen release in the sodium removing process can be reduced, so that the performance of the battery is improved. For example, taking F as an example, the bond energy of F is relatively strong, and the F can not be released like oxygen to react with electrolyte, even if the reaction is carried out, inorganic salt is generated to form on the surface of the material, so that the stability of circulation can be greatly improved; in addition, the F particle size increases the path of ionic conduction, so that collapse of the material structure is less likely to occur.

Alternatively, 0.05.ltoreq.y.ltoreq.0.25.

It is understood that as the value of y increases, the molar mass of Na in the chemical formula decreases, affecting the sodium supplementing effect of the sodium supplementing material, and the range of y values in the above range provides better structural stability of the sodium supplementing material.

Optionally, the sodium supplement material has a Dv50 range value of 1 μm to 20 μm.

Optionally, the sodium supplement material has a Dv50 range value of 3 μm to 15 μm.

The sodium supplementing material is used in the positive electrode coating to improve sodium loss in the circulation process, the sodium supplementing material needs to be mixed with the positive electrode material, and the Dv50 of the sodium supplementing material is in the range, so that the coating process, such as gel, can be improved, and the problem of uneven distribution of the sodium supplementing material can be solved. It can be understood that under the condition that the quality of the sodium supplementing material is kept unchanged, as the size of the sodium supplementing material is increased, the particle number of the sodium supplementing material is reduced, the distribution of the sodium supplementing material in the active layer is uneven, under the condition that the distribution of the sodium supplementing material is uneven, the capacity of a coating part with the sodium supplementing material is higher, sodium can be separated out from a negative electrode in the process of removing sodium, and higher requirements are put forward on the capacity of the negative electrode, so that the Dv50 of the sodium supplementing material can alleviate the problems in the range.

Optionally, a conductive layer is arranged on the surface of the sodium supplementing material.

The conductive layer is arranged on the surface of the sodium supplementing material, so that the stability of the sodium supplementing material can be improved, and the electronic conductivity of the sodium supplementing material can be improved. It can be understood that the contact between the electrolyte and the sodium supplementing material can be blocked by the coating of the conductive layer, so that the stability of the sodium supplementing material is improved and the removal of lattice oxygen is improved.

Optionally, the conductive layer includes at least one of a carbon material and a conductive polymer.

The carbon material and the conductive polymer have conductive performance, so that the conductivity of the sodium supplementing material can be improved, and the rate performance and the cycle performance of the battery can be improved.

Optionally, the carbon material comprises at least one of carbon nanotubes, graphene, graphite, carbon black;

and/or the conductive polymer comprises at least one of polypyrrole, polyethylene glycol, polyaniline and poly (3, 4-ethylenedioxythiophene).

In the application, the carbon material comprises at least one of carbon nano tube, graphene, graphite and carbon black, and has better adsorptivity, can adsorb oxygen released by the sodium supplementing material, and can reduce the amount of oxygen entering the electrolyte. The conductive polymer includes, but is not limited to, at least one of polypyrrole, polyethylene glycol, polyaniline, and poly (3, 4-ethylenedioxythiophene).

Optionally, the conductive layer has a thickness ranging from 10nm to 300nm.

Optionally, the conductive layer has a thickness ranging from 50nm to 200nm.

The thickness of the conductive layer in the application is in the range, the blocking of the conductive layer to the electrolyte can be facilitated, the contact between the sodium supplementing material and the electrolyte is reduced, the stability of the sodium supplementing material is improved, the removal of lattice oxygen is improved, and meanwhile, the energy density of the battery can be improved. It is understood that the ability to block the electrolyte improves as the thickness of the conductive layer increases within a certain range, but affects the energy density of the battery when the thickness of the conductive layer is too thick.

Optionally, the conductive layer is entirely coated on the surface of the sodium supplementing material.

Considering that the sodium supplementing material directly contacts with the electrolyte, side reaction, namely, the phenomenon of releasing lattice oxygen is generated, the generation of oxygen can further accelerate the generation of the side reaction, and the circulation stability of the active material is affected; in order to reduce the phenomenon of the removal of lattice oxygen, the conductive layer is fully coated on the surface of the sodium supplementing material, so that the exposure of the sodium supplementing material to electrolyte can be reduced, the stability of the sodium supplementing material is improved, and the phenomenon of the removal of lattice oxygen is reduced.

The application also provides a preparation method of the sodium supplementing material, which comprises the following steps:

placing a metal source and a sodium source in a solvent, and mixing to obtain first slurry;

drying the first slurry to obtain a first precursor;

mixing the first precursor and the additive containing M2 element in inert atmosphereMedium sintering to obtain sodium supplementing material; the chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S.

In the step of preparing the sodium supplementing material, a metal source and a sodium source are placed in a solvent and mixed to obtain first slurry; drying the first slurry to obtain a first precursor; and mixing the first precursor and the additive containing M2 element, and sintering in inert atmosphere to obtain the sodium supplementing material.

Optionally, after the step of mixing the first precursor and the additive containing M2 element and sintering in an inert atmosphere to obtain the sodium supplementing material, the method further comprises the following steps:

and mixing the obtained sodium supplementing material with a conductive material, and sintering in an inert atmosphere to obtain the sodium supplementing material coated with the conductive material.

In the step of preparing the sodium supplement material, the conductive material can be added in the preparation process to prepare the sodium supplement material coated by the conductive material.

Optionally, in the step of mixing the obtained sodium supplement material with a conductive material and sintering in an inert atmosphere to obtain a conductive material coated sodium supplement material, when the conductive material comprises a carbon material, the sintering temperature is 500 ℃ to 900 ℃ and the sintering time is 6 hours to 12 hours; when the conductive material is a conductive polymer, the sintering temperature is 150-450 ℃ and the sintering time is 2-8 h.

Considering that the conductive material is coated on the surface of the sodium supplementing material in a sintering manner, the conductive polymer is structurally damaged at a certain temperature, and for this reason, when the conductive material comprises a carbon material, the sintering temperature is 500-900 ℃ and the time is 6-12 h; when the conductive material is a conductive polymer, the sintering temperature is 150-450 ℃ and the sintering time is 2-8 h.

Optionally, in the step of mixing the first precursor and the additive containing the M2 element and sintering in an inert atmosphere to obtain the sodium supplementing material, the sintering temperature is 500-900 ℃ and the sintering time is 6-12 h.

In the step of preparing the M2 element substituted partial lattice oxygen, the first precursor and the additive containing the M2 element are mixed and sintered in inert atmosphere to obtain the sodium supplementing material, the sintering temperature is 500-900 ℃ and the sintering time is 6-12 h.

Optionally, in the step of placing the metal source and the sodium source in a solvent and mixing to obtain the first slurry, the method comprises the following steps:

and (3) adding a metal source and a sodium source into a solvent containing a surfactant, and mixing to obtain first slurry.

In order to improve the uniformity of mixing the metal source and the sodium source, a surfactant is put into a solvent, so that the performance of the sodium supplementing material is improved.

Optionally, in the step of drying the first slurry to obtain the first precursor, the method includes the following steps:

and drying the first slurry by adopting a spray drying mode, wherein the spray drying temperature is 120-180 ℃, and the feeding speed is 5-20 ml/min.

Further milling is required to obtain a material of suitable size, considering that the first precursor obtained in the usual drying step is susceptible to agglomeration. In order to reduce the milling process steps, a spray drying step is adopted to directly obtain the material with proper size, and the uniformity and uniformity of the particle size of the material are higher. The spray drying temperature is 120 ℃ to 180 ℃ and the feeding speed is 5ml/min to 20ml/min.

Optionally, the metal source comprises one or more of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo powder and metal oxides thereof;

And/or the sodium source comprises one or more of sodium oxide, sodium hydroxide, sodium peroxide, sodium carbonate, sodium bicarbonate, sodium sulfate, sodium phosphate, sodium nitrate, sodium acetate, sodium chloride or sodium fluoride;

and/or the additive containing M2 element comprises at least one of ammonium fluoride, fluorocyclobutane, fluotributylamine, fluorodecalin, vinylidene fluoride, difluoromethane chloride, hydroxylamine hydrochloride, urea, paranitroaniline, dicyandiamide, pyrophosphoric acid, phospholipid, thioacetamide, diallyl thiosulfate and diallyl trithio;

and/or the conductive material comprises a carbon material comprising at least one of carbon black, acetylene black, carbon nanotubes, sucrose, glucose;

and/or, the molar ratio range value of the metal element in the metal source and sodium in the sodium source is more than 1.0 and less than or equal to 1.2;

and/or the mass ratio of the conductive material to the first precursor ranges from 0 to 10%.

Metal sources herein include, but are not limited to, one or more of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo powder and metal oxides thereof. Sodium sources include, but are not limited to, one or more of sodium oxide, sodium hydroxide, sodium peroxide, sodium carbonate, sodium bicarbonate, sodium sulfate, sodium phosphate, sodium nitrate, sodium acetate, sodium chloride, or sodium fluoride. The M2 element-containing additive includes, but is not limited to, at least one of ammonium fluoride, fluorocyclobutane, fluorotributylamine, fluorodecalin, vinylidene fluoride, difluoromethane chloride, hydroxylamine hydrochloride, urea, p-nitroaniline, dicyandiamide, pyrophosphoric acid, phospholipids, thioacetamide, diallyl thiosulfate, diallyl trisulfide. The conductive material includes, but is not limited to, a carbon material including, but not limited to, at least one of carbon black, acetylene black, carbon nanotubes, sucrose, glucose.

In the process of preparing the sodium supplementing material, the molar ratio of the metal element in the metal source and sodium in the sodium source ranges from a value greater than 1.0 to a value less than or equal to 1.2, i.e., according to the chemical formula Na of the sodium supplementing material _x M1O _4-y M2 _y The raw materials were mixed in a ratio of the metal element to sodium.

In order to obtain a conductive layer of suitable thickness, the mass ratio of the conductive material to the mass of the first precursor ranges from 0 to 10%.

The application also provides a positive pole piece, which comprises the sodium supplementing material;

or the positive pole piece comprises the sodium supplementing material obtained by the preparation method of the sodium supplementing material.

Optionally, the positive electrode sheet includes an active material, and the mass percentage of the sodium supplementing material is greater than 0 and less than or equal to 20%, preferably 5% to 15% of the total mass of the active material and the sodium supplementing material.

The loss of sodium ions leads to low first cycle efficiency of the sodium ion battery, about 75 to 85 percent, and the sodium supplementing material accounts for the total mass of the active material and the sodium supplementing material in the range, so that the loss of sodium ions can be supplemented, the battery performance is improved, and the energy density is improved. It will be appreciated that if the mass of the sodium compensating material is too large as a percentage of the total mass of the active material and the sodium compensating material, the amount of active material is reduced, and that considering that the performance of the sodium compensating material is inferior to that of the active material, the amount of sodium compensating material is increased at this time, which may reduce the battery performance.

Optionally, the positive electrode plate includes a current collector and a coating layer disposed on at least one side of the current collector, the coating layer includes at least two active layers, the at least two active layers are disposed on the same side of the current collector, at least one active layer is disposed on the current collector, and at least one other active layer is disposed on a side of the at least one active layer facing away from the current collector;

defining the percentage of the mass of the sodium supplementing material in at least one active layer to the total mass of the active material and the sodium supplementing material in at least one active layer as W1, and the percentage of the mass of the sodium supplementing material in at least one other active layer to the total mass of the active material and the sodium supplementing material in at least one other active layer as W2, wherein W1 is larger than W2.

Considering that the main reason for oxygen release of the sodium supplementing material is that oxygen is generated by contact with the electrolyte, in order to improve the oxygen release of the sodium supplementing material, the sodium supplementing material is arranged at a position in the coating layer which is not easy to contact with the electrolyte, so that the oxygen release of the sodium supplementing material is improved. Specifically, as shown in fig. 2, the positive electrode sheet comprises a current collector and a coating layer arranged on at least one side of the current collector, the coating layer comprises at least two active layers, the at least two active layers are arranged on the same side of the current collector, at least one active layer is arranged on the current collector, at least one other active layer is arranged on one side of the at least one active layer, which is away from the current collector, so that the at least one other active layer is arranged on the surface of the at least one active layer, and the probability of contact between the at least one active layer and electrolyte is reduced; the weight percentage of the sodium supplementing material in at least one active layer to the total weight of the active material and the sodium supplementing material in at least one active layer is defined as W1, the weight percentage of the sodium supplementing material in at least one other active layer to the total weight of the active material and the sodium supplementing material in at least one other active layer is defined as W2, and the condition that W1 is larger than W2 is satisfied. That is, the at least one active layer is less likely to contact the electrolyte than the at least one other active layer, and the percentage by mass of the sodium compensating material in the at least one active layer relative to the total mass of the active material and the sodium compensating material in the at least one active layer is greater than the at least one other active layer, thereby improving the contact of the sodium compensating material with the electrolyte and improving the oxygen release problem of the sodium compensating material.

The application also provides an electrode assembly comprising a negative electrode plate, an electrolyte, and a positive electrode plate.

The present application also provides a battery comprising an electrode assembly as described.

The application also provides an electric device comprising the battery.

The chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S. By adopting M2 element to replace part of lattice oxygen, the structural stability of the sodium supplementing material can be improved, and the oxygen release in the sodium removing process can be reduced, so that the performance of the battery is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic structural diagram of a sodium supplement material according to an embodiment of the present application;

FIG. 2 is a schematic structural view of a positive electrode sheet according to an embodiment of the present application;

FIG. 3 is a process flow diagram of the preparation of a sodium supplement material according to an embodiment of the present application;

FIG. 4 is a schematic illustration of a battery cell according to an embodiment of the present application;

fig. 5 is an exploded view of the battery cell of an embodiment of the present application shown in fig. 4;

fig. 6 is a schematic view of a battery module according to an embodiment of the present application;

FIG. 7 is a schematic view of a battery pack according to an embodiment of the present application;

FIG. 8 is an exploded view of the battery pack of one embodiment of the present application shown in FIG. 7;

fig. 9 is a schematic view of an electric device in which a battery cell according to an embodiment of the present application is used as a power source.

Reference numerals illustrate:

the achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Embodiments of the sodium supplement material, the method of producing the same, the positive electrode sheet, the electrode assembly, the battery, and the electric device of the present application are specifically disclosed below in detail with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.

All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.

All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

There is a problem of sodium loss during the cycling of the sodium secondary battery. For example, the SEI process for initial film formation of a battery consumes a large amount of active sodium, resulting in a decrease in the first-week efficiency of a sodium secondary battery.

Sodium supplements are typically used to replace sodium losses. However, there are problems in supplementing sodium with sodium supplements. For example, lattice oxygen can be removed in the sodium supplementing agent sodium removing process, and the lattice oxygen reacts with electrolyte to generate oxygen to release an anode, so that the gas yield in the formation process is high, the film forming is unstable, the interface is abnormal and the subsequent cycle life is influenced, and part of active oxygen remains in the electrolyte and gradually oxidizes the electrolyte although most of gas can be pumped away in the negative pressure formation process, so that the gas yield in the later stage of a cell is overlarge, and the valve of the cell is opened to spray liquid.

In order to solve the above problems, the present application provides a sodium supplementing material, the chemical formula of the sodium supplementing material comprises Na _x M1O _4- _y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S.

The sodium supplementing material comprises metal oxide of sodium element, can remove sodium ions in the secondary battery, and supplements sodium loss in the secondary battery.

By adopting M2 element to replace part of lattice oxygen, the structural stability of the sodium supplementing material can be improved, and the oxygen release in the sodium removing process can be reduced, so that the performance of the battery is improved. For example, taking F as an example, the bond energy of F is relatively strong, and the F can not be released like oxygen to react with electrolyte, even if the reaction is carried out, inorganic salt is generated to form on the surface of the material, so that the stability of circulation can be greatly improved; in addition, the F particle size increases the path of ionic conduction, so that collapse of the material structure is less likely to occur.

Lattice oxygen, bulk oxygen constituting a crystal structure, e.g. TiO ₂ Oxygen constituting an anatase structure.

In the above-mentioned range of 2.ltoreq.x < 8, the values include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, point values in the embodiments and values of 2, 3, 4, 5, 6, 7, 7.5, etc., and ranges between any two of the above-mentioned point values.

The values 0.01.ltoreq.y.ltoreq.0.35 include the minimum and maximum values of the range, and each value between such minimum and maximum values, specific examples include, but are not limited to, the point values in the examples and the range values between any two of the above-mentioned point values of 0.01, 0.02, 0.05, 0.08, 0.1, 0.15, 0.18, 0.2, 0.25, 0.28, 0.3, 0.33, 0.35, and the like.

In one embodiment, 0.05.ltoreq.y.ltoreq.0.25.

It is understood that as the value of y increases, the molar mass of Na in the chemical formula decreases, affecting the sodium supplementing effect of the sodium supplementing material to some extent, and the range of values of y is within the above range, and the structural stability of the sodium supplementing material is better.

In one embodiment, the Dv50 value of the sodium supplement material ranges from 1 μm to 20 μm, preferably from 3 μm to 15 μm.

Dv50, in the sample particles, 50% of the total volume of particles have a particle size greater than this value, and 50% of the total volume of particles have a particle size less than this value; dv50 may represent the median particle diameter of the sample.

Dv50 may be tested using methods well known in the art. By way of example, reference may be made to GB/T19077-2016 for characterization tests using a Markov laser particle sizer, such as a Malvern Mastersizer-3000 or the like.

In one embodiment, the surface of the sodium supplement material is provided with a conductive layer.

As shown in fig. 1, a conductive layer 20 is disposed on the surface of the sodium supplement material 10, the conductive layer 20 is coated on the surface of the sodium supplement material 10, and the conductive layer includes a material for transporting charges.

In one embodiment, the conductive layer comprises at least one of a carbon material, a conductive polymer.

Conductive polymers, polymers themselves have the ability to transport charge.

In an embodiment, the carbon material comprises at least one of carbon nanotubes, graphene, graphite, carbon black; and/or the conductive polymer comprises at least one of polypyrrole, polyethylene glycol, polyaniline, and poly (3, 4-ethylenedioxythiophene).

In an embodiment, the thickness of the conductive layer ranges from 10nm to 300nm, preferably from 50 to 200nm.

The thickness of the conductive layer in the application is in the range, the blocking of the conductive layer to the electrolyte can be facilitated, the contact between the sodium supplementing material and the electrolyte is reduced, the stability of the sodium supplementing material is improved, the removal of lattice oxygen is improved, and meanwhile, the energy density of the battery can be improved. It is understood that the ability to block the electrolyte improves as the thickness of the conductive layer increases within a certain range, but the energy density of the battery is affected to some extent when the thickness of the conductive layer is too thick.

The above 10nm to 300nm values include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, point values in the embodiments and values of 10nm, 30nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, 200nm, 250nm, 300nm, and the like, and ranges between any two of the above point values.

In one embodiment, the conductive layer is entirely coated on the surface of the sodium supplement material.

The full coating means that the coating material is continuously coated on the surface of the sodium supplementing material, so that the surface of the sodium supplementing material is lightened from being exposed.

Considering that the sodium supplementing material directly contacts with electrolyte, side reaction can be generated, the phenomenon of releasing lattice oxygen can be generated, the generation of oxygen can further accelerate the generation of side reaction, and the circulation stability performance of the active material is affected; in order to reduce the phenomenon of the removal of lattice oxygen, the conductive layer is fully coated on the surface of the sodium supplementing material, so that the exposure of the sodium supplementing material to electrolyte can be reduced, the stability of the sodium supplementing material is improved, and the phenomenon of the removal of lattice oxygen is reduced.

As shown in fig. 3, the present application further provides a preparation method of the sodium supplementing material, including: placing a metal source and a sodium source in a solvent, and mixing to obtain first slurry; Drying the first slurry to obtain a first precursor; mixing the first precursor and an additive containing M2 element, and sintering in inert atmosphere to obtain a sodium supplementing material; the chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S.

It is understood that the additive containing M2 element may be at least one of an F-containing additive, an N-containing additive, a P-containing additive, and an S-containing additive.

In one embodiment, after the step of mixing the first precursor and the additive containing M2 element and sintering in an inert atmosphere to obtain the sodium supplement material, the method further comprises the following steps: and mixing the obtained sodium supplementing material with a conductive material, and sintering in an inert atmosphere to obtain the sodium supplementing material coated by the conductive material.

In an embodiment, in the step of mixing the obtained sodium supplement material with a conductive material and sintering in an inert atmosphere to obtain a conductive material coated sodium supplement material, when the conductive material includes a carbon material, the sintering temperature is 500 ℃ to 900 ℃ and the time is 6 hours to 12 hours; when the conductive material is a conductive polymer, the sintering temperature is 150 ℃ to 450 ℃ and the sintering time is 2 hours to 8 hours.

Considering that the conductive material is coated on the surface of the sodium supplementing material in a sintering manner, the conductive polymer is structurally damaged at a certain temperature, and for this reason, when the conductive material comprises a carbon material, the sintering temperature is 500-900 ℃ and the sintering time is 6-12 h; when the conductive material is a conductive polymer, the sintering temperature is 150 ℃ to 450 ℃ and the sintering time is 2 hours to 8 hours.

The values of 500 c to 900 c described above include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, the dot values in the embodiments and the range values of 500 c, 600 c, 700 c, 800 c, 900 c, etc., and between any two of the dot values described above.

The values in the above 6h to 12h include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, point values in the embodiment and values of the range between any two of the above-mentioned point values, such as 6h, 7h, 8h, 9h, 10h, 11h, 12h, and the like.

The values of 150 c to 450 c described above include the minimum and maximum values of the range, and each value between such minimum and maximum values, and specific examples include, but are not limited to, the point values in the examples and the range values of 150 c, 200 c, 250 c, 300 c, 350 c, 400 c, 450 c, etc., and between any two of the above-described point values.

The values in the above 2h to 8h include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, point values in the embodiment and values in the range between 2h, 3h, 4h, 5h, 6h, 7h, 8h, and the like.

In one embodiment, in the step of mixing the first precursor and the additive containing M2 element and sintering in an inert atmosphere to obtain the sodium supplementing material, the sintering temperature is 500 ℃ to 900 ℃ and the sintering time is 6h to 12h.

In the step of preparing fluorine substituted partial lattice oxygen, the first precursor and the fluorine-containing additive are mixed and sintered in an inert atmosphere to obtain the sodium supplementing material, the sintering temperature is 500-900 ℃ and the sintering time is 6-12 h.

In one embodiment, in the step of mixing a metal source and a sodium source in a solvent to obtain a first slurry, the method comprises the steps of: and (3) adding a metal source and a sodium source into a solvent containing a surfactant, and mixing to obtain first slurry.

In order to improve the uniformity of mixing the metal source and the sodium source, a surfactant is put into a solvent, so that the performance of the sodium supplementing material is improved. The kind of the surfactant is not limited, and for example, sodium linear alkylbenzenesulfonate, sodium α -alkenylsulfonate, and the like may be used. The solvent may be water, methanol, ethanol, etc.

In one embodiment, in the step of drying the first slurry to obtain the first precursor, the method includes the steps of: the first slurry is dried by spray drying at 120-180deg.C at a feed rate of 5-20 ml/min.

The values of 120 ℃ to 180 ℃ described above include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, the point values in the examples and the values of 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, and the like, and the range values between any two of the above-described point values.

The above 5ml/min to 20ml/min, the values include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, specific examples include, but are not limited to, dot values in the examples and values of the range between any two of the above dot values of 5ml/min, 6ml/min, 7ml/min, 8ml/min, 9ml/min, 10ml/min, 11ml/min, 12ml/min, 13ml/min, 14ml/min, 15ml/min, 16ml/min, 17ml/min, 18ml/min, 19ml/min, 20ml/min, and the like.

In one embodiment, the metal source comprises one or more of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo powder and its metal oxides; and/or the sodium source comprises one or more of sodium oxide, sodium hydroxide, sodium peroxide, sodium carbonate, sodium bicarbonate, sodium sulfate, sodium phosphate, sodium nitrate, sodium acetate, sodium chloride or sodium fluoride; and/or the additive containing M2 element comprises at least one of ammonium fluoride, fluorocyclobutane, fluotributylamine, fluorodecalin, vinylidene fluoride, difluoromethane chloride, hydroxylamine hydrochloride, urea, paranitroaniline, dicyandiamide, pyrophosphoric acid, phospholipid, thioacetamide, diallyl thiosulfate and diallyl trithio; and/or the conductive material comprises a carbon material, the carbon material comprises at least one of carbon black, acetylene black, carbon nanotubes, sucrose, and glucose; and/or the molar ratio range value of the metal element in the metal source and sodium in the sodium source is more than 1.0 and less than or equal to 1.2; and/or the mass ratio of the conductive material to the first precursor ranges from 0 to 10%.

The preparation process of the sodium supplementing material comprises the steps of mixing the obtained sodium supplementing material with a conductive material, and sintering in an inert atmosphere to obtain the sodium supplementing material coated by the conductive material. It is understood that the conductive material refers to a material that is itself conductive prior to sintering in an inert atmosphere, e.g., carbon black, acetylene black, carbon nanotubes. Or a material having conductive properties such as sucrose, glucose, etc., after sintering in an inert atmosphere. The structure of the materials comprises carbon, and the carbon is used for being coated on the surface of the sodium supplementing material after being sintered in an inert atmosphere to form a conductive layer, and the materials can be carbon coating materials.

In an embodiment, the present application further provides a positive electrode sheet, where the positive electrode sheet includes the sodium supplementing material as described above; or the positive electrode plate comprises the sodium supplementing material obtained by the preparation method of the sodium supplementing material.

In one embodiment, the positive electrode sheet includes an active material, and the percentage of the mass of the sodium supplementing material to the total mass of the active material and the sodium supplementing material is greater than 0 and less than or equal to 20%, preferably 5% to 15%.

In one embodiment, the positive electrode plate comprises a current collector and a coating layer arranged on at least one side of the current collector, the coating layer comprises at least two active layers, the at least two active layers are arranged on the same side of the current collector in a layer-by-layer manner, at least one active layer is arranged on the current collector, and at least one other active layer is arranged on the side, away from the current collector, of the at least one active layer; the weight percentage of the sodium supplementing material in at least one active layer to the total weight of the active material and the sodium supplementing material in at least one active layer is defined as W1, the weight percentage of the sodium supplementing material in at least one other active layer to the total weight of the active material and the sodium supplementing material in at least one other active layer is defined as W2, and the condition that W1 is larger than W2 is satisfied.

The current collector refers to a structure or a part for collecting current, and the current collector mainly refers to metal foils such as copper foil and aluminum foil on the lithium ion battery. The current collector is used as a base material for attaching an anode or a cathode active material, and plays a role in collecting current generated by the active material and outputting large current. Generally, aluminum foil is used as a positive current collector, and copper foil is used as a negative current collector.

As shown in fig. 2, a schematic structural diagram of an embodiment of a positive electrode sheet is shown, where the coating 40 includes two active layers, at least one active layer 41 and at least one other active layer 42, and the two active layers are stacked on the same side of the current collector.

Considering that the main reason for oxygen release of the sodium supplementing material is that oxygen is generated by contact with the electrolyte, in order to improve the oxygen release of the sodium supplementing material, the sodium supplementing material is arranged at a position in the coating layer which is not easy to contact with the electrolyte, so that the oxygen release of the sodium supplementing material is improved.

Specifically, as shown in fig. 2, the positive electrode sheet 100 includes a current collector 30 and a coating 40 disposed on at least one side of the current collector, the coating includes at least two active layers, the at least two active layers are disposed on the same side of the current collector, at least one active layer 41 is disposed on the current collector, and at least one other active layer 42 is disposed on a side of the at least one active layer facing away from the current collector, so that the at least one other active layer is disposed on a surface of the at least one active layer, thereby reducing a probability of the at least one active layer contacting with an electrolyte; the percentage by mass of the sodium compensating material in the at least one active layer 41 to the total mass of the active material and the sodium compensating material in the at least one active layer 41 is defined as W1, the percentage by mass of the sodium compensating material in the at least one other active layer 42 to the total mass of the active material and the sodium compensating material in the at least one other active layer 42 is defined as W2, and W1 is satisfied to be greater than W2. That is, the at least one active layer is less likely to contact the electrolyte than the at least one other active layer, and the percentage by mass of the sodium compensating material in the at least one active layer relative to the total mass of the active material and the sodium compensating material in the at least one active layer is greater than the at least one other active layer, thereby improving the contact of the sodium compensating material with the electrolyte and improving the oxygen release problem of the sodium compensating material.

In one embodiment, the present application also provides an electrode assembly comprising a negative electrode sheet, an electrolyte, and a positive electrode sheet as described above.

The positive electrode plate adopts all the technical schemes of all the embodiments, so that the positive electrode plate has at least all the beneficial effects brought by the technical schemes of the embodiments, and the positive electrode plate is not described in detail herein.

In one embodiment, the present application also provides a battery comprising an electrode assembly as described above.

The electrode assembly adopts all the technical schemes of all the embodiments, so that the electrode assembly has at least all the beneficial effects brought by the technical schemes of the embodiments, and the description is omitted herein.

It is understood that the battery includes a battery cell, a battery module, and a battery pack.

In an embodiment, the present application further provides an electric device, where the electric device includes a battery as described above.

The battery adopts all the technical schemes of all the embodiments, so that the battery has at least all the beneficial effects brought by the technical schemes of the embodiments, and the description is omitted herein.

The battery (battery cell, battery module, battery pack) and the power consumption device of the present application will be described below with reference to the drawings as appropriate.

In one embodiment of the present application, a battery cell is provided.

Typically, the battery cell includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The diaphragm is arranged between the positive pole piece and the negative pole piece, mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and can enable ions to pass through. The separator is the improved separator described above in the present application.

The positive pole piece comprises a positive current collector and a positive film layer arranged on at least one surface of the positive current collector.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode film layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.

In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.

The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material.

As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode film layer is provided on either one or both of the two surfaces opposing the anode current collector.

In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and the like. The silicon-based material may be at least one selected from elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the negative electrode film layer further optionally includes a binder. The binder may be at least one selected from Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

In some embodiments, the negative electrode film layer further optionally includes a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the negative electrode film layer may optionally further include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In some embodiments, the negative electrode sheet may be prepared by: dispersing the above components for preparing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.

The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The type of electrolyte is not particularly limited in this application, and may be selected according to the need.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

In some embodiments, the battery cell further includes a separator. The type of separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.

In some embodiments, the material of the separator may be at least one selected from glass fiber, non-woven 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 the respective layers may be the same or different, and are not particularly limited.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the battery cell may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.

In some embodiments, the exterior packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell may also be a pouch, such as a pouch-type pouch. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

The shape of the battery cell is not particularly limited in this application, and may be cylindrical, square, or any other shape. For example, fig. 4 is a square-structured battery cell 5 as one example.

In some embodiments, referring to fig. 5, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 may be one or more, and those skilled in the art may select the number according to specific practical requirements.

In some embodiments, the battery cells may be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.

Fig. 6 is a battery module 4 as an example. Referring to fig. 6, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of battery cells 5 may be further fixed by fasteners.

Alternatively, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

Fig. 7 and 8 are battery packs 1 as an example. Referring to fig. 7 and 8, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

In addition, the application also provides an electric device, which comprises at least one of the battery cell, the battery module or the battery pack. The battery cell, the battery module, or the battery pack may be used as a power source of the electric device, and may also be used as an energy storage unit of the electric device. The power utilization device may include, but is not limited to, mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric only 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, and the like.

As the power consumption device, a battery cell, a battery module, or a battery pack may be selected according to the use requirements thereof.

Fig. 9 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the power device for the battery cells, a battery pack or battery module may be employed.

As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a battery cell can be used as a power supply.

Examples

Example 1

Preparation of sodium supplementing material

Metal source (Ni (OH) ₂ ) The sodium source (sodium carbonate) was dispersed in a surfactant (sodium dodecylbenzenesulfonate) and water (1% of the total mass) at a molar ratio of Ni to Na of 1.05, and the mixture was mixed by shaking using an oscillator and zircon to obtain a first slurry.

Spray drying the first slurry to directly obtain a granular first precursor; the spray drying temperature was 160℃and the feed rate was 10ml/min.

Mixing a first precursor and an additive containing M2 element (fluorocyclobutane) and sintering in an inert atmosphere to obtain a sodium supplementing material; sintering temperature is 700 ℃ and sintering time is 8 hours. Uniformly mixing the sodium supplementing material and a conductive material carbon nanotube (the mass ratio of the carbon material to the first precursor is 5%), and sintering in an inert atmosphere to obtain a conductive material coated sodium supplementing material; sintering temperature is 700 ℃ and sintering time is 8 hours.

To obtain sodium supplementThe chemical formula of the material is Na ₆ NiO _3.9 F _0.1 The Dv50 of the sodium supplementing material is 10 mu m, and the thickness of the conducting layer is 100nm.

Preparation of sodium positive electrode plate

Preparation of sodium cathode active Material (NaFePO) ₄ ) The mass ratio of the sodium supplementing material to the binder (PVDF) to the conductive agent (acetylene black) is 90:5:5, mixing, wherein the mass of the sodium supplementing material accounts for 5% of the total mass of the positive electrode active material and the sodium supplementing material, adding a solvent (N-methyl pyrrolidone), preparing to obtain slurry, coating the slurry on an aluminum foil current collector, uniformly coating the slurry on the aluminum foil current collector, and drying, cold pressing and cutting to obtain the positive electrode plate.

Preparation of negative electrode plate

The active material artificial graphite, conductive agent carbon black, binder Styrene Butadiene Rubber (SBR) and thickener sodium hydroxymethyl cellulose (CMC) are mixed according to the weight ratio of 96.2:0.8:0.8:1.2, dissolving in deionized water serving as a solvent, and uniformly mixing to prepare negative electrode slurry; and uniformly coating the negative electrode slurry on a negative electrode current collector copper foil once or a plurality of times, and drying, cold pressing and cutting to obtain a negative electrode plate.

Preparation of electrolyte

In an argon atmosphere glove box (H ₂ O<0.1ppm，O ₂ <0.1 ppm), mixing organic solvent Ethylene Carbonate (EC)/methyl ethyl carbonate (EMC) according to volume ratio of 3/7, adding 12.5% NaPF ₆ The sodium salt is dissolved in the organic solvent and stirred uniformly.

Isolation film

A polypropylene film was used as a separator.

Preparation of sodium ion batteries

The positive electrode plate, the isolating film and the negative electrode plate of the embodiment 1 are sequentially stacked, the isolating film is positioned between the positive electrode plate and the negative electrode plate to play a role of isolation, then the bare cell is obtained by winding, the tab is welded on the bare cell, the bare cell is arranged in an aluminum shell, baking and dewatering are carried out at 100 ℃, and then electrolyte is injected and sealed, so that the uncharged battery is obtained. The uncharged battery was subjected to the processes of standing, hot and cold pressing, formation, shaping, capacity test and the like in sequence to obtain the sodium ion battery product of example 1.

Example 2

Based on example 2, the proportion of the sodium supplement material was adjusted to 10%.

Example 3

Based on example 2, the proportion of the sodium supplement material was adjusted to 15%.

Examples 4 to 7

The amount of fluorine-containing additive was adjusted on the basis of example 2.

Examples 8 to 12

On the basis of example 2, the particle size of the sodium supplement material was adjusted.

Example 13

On the basis of example 2, no carbon coating layer was provided.

Example 14 and example 15

The thickness of the carbon coating layer was adjusted on the basis of example 2.

Example 16

On the basis of example 2, the metal source was regulated.

Example 17

Based on example 2, carbon nanotubes were replaced with conductive polymers (polyaniline).

Example 18

On the basis of example 2, the additive containing M2 element was replaced with a sulfur-containing compound (thioacetamide).

Comparative example 1

On the basis of example 1, no sodium supplement material was added.

Comparative example 2

On the basis of the embodiment 1, the fluorine-containing additive and the carbon coating layer are not added into the sodium supplementing material.

Testing procedure of full battery first effect

After the battery cell is filled with liquid, two procedures of formation and capacity division, namely a charging process is needed, and the first step of formation and capacity division is a charging process, and the sum of the two capacities is that the whole battery is charged with the capacitor for the first time; the second step of the capacity-dividing process is to discharge from a full-charge state to an empty-charge state, and thus the capacity of the step is the discharge capacity of the full battery. Combining the two results in the algorithm of the first efficiency of the full battery: full cell first efficiency = capacity split second step discharge capacity/(formation charge capacity + capacity split first step charge capacity).

Cycle performance test procedure

At 45 ℃, the battery cell is charged to 4.3V with a constant current of 1C, further charged to 0.05C with a constant voltage of 4.3V, and then discharged to 2V with a constant current of 1C, which is a charge-discharge cycle process, and the discharge capacity of this time is the discharge capacity of the 1 st cycle. And carrying out repeated cycle charge and discharge tests on the battery according to the mode, detecting to obtain the discharge capacity of the 200 th cycle, and calculating the capacity retention rate of the battery monomer after the cycle according to the following formula. Capacity retention (wt%) after 200 cycles of the battery= [ discharge capacity of 200 th cycle/discharge capacity of 1 st cycle ] ×100wt%.

Table 1 list of experimental data

Table 2 list of experimental data

In example 19, based on example 2, the sodium supplement material was disposed in two active layers, and referring to the schematic structural diagram of fig. 2, the thickness of the two coating layers was the same, the sum of the mass of the sodium supplement material and the mass of the active material in the two coating layers was the same, and the total sodium supplement material in the two active layers accounted for 10% of the total mass of the sodium supplement material and the active material in the two active layers.

As can be seen from the table above: according to the method, the sodium supplementing material is added into the positive electrode plate, so that the performance of the battery can be improved. Specifically, in comparative examples and comparative examples, in which the lattice oxygen portion in the sodium supplementing material was replaced with an element containing M2 and the cycle performance of the battery was improved, comparative examples 19 and 2, in which the sodium supplementing material was provided in two active layers, define the percentage of the mass of the sodium supplementing material in at least one active layer to the total mass of the active material and the sodium supplementing material in at least one active layer as W1 (7%), the percentage of the mass of the sodium supplementing material in at least one other active layer to the total mass of the active material and the sodium supplementing material in at least one other active layer as W2 (3%), and satisfy W1 greater than W2. That is, the at least one active layer is less likely to contact the electrolyte than the at least one other active layer, and the percentage by mass of the sodium compensating material in the at least one active layer relative to the total mass of the active material and the sodium compensating material in the at least one active layer is greater than the at least one other active layer, thereby improving the contact of the sodium compensating material with the electrolyte and improving the oxygen release problem of the sodium compensating material.

The foregoing description of the preferred embodiments of the present invention should not be construed as limiting the scope of the invention, but rather as utilizing equivalent structural changes made in the description of the invention and the accompanying drawings, or as directly/indirectly employed in other related technical fields, are included in the scope of the invention.

Claims

1. The positive pole piece of the sodium ion battery is characterized by comprising an active material and a sodium supplementing material, wherein the chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S;

the Dv50 value of the sodium supplement material is in the range of 1 μm to 20 μm;

the mass percentage of the sodium supplementing material accounting for the total mass of the active material and the sodium supplementing material is more than 0 and less than or equal to 20 percent;

the positive electrode plate comprises a current collector and a coating layer arranged on at least one side of the current collector, wherein the coating layer comprises at least two active layers, the at least two active layers are arranged on the same side of the current collector layer by layer, at least one active layer is arranged on the current collector, and at least one other active layer is arranged on one side, away from the current collector, of the at least one active layer;

2. The positive electrode plate of sodium ion battery of claim 1, wherein y is 0.05-0.25.

3. A positive electrode sheet for a sodium ion battery as claimed in claim 1 or 2, wherein the Dv50 value of the sodium supplementing material is in the range of 3 μm to 15 μm.

4. The positive electrode sheet of sodium ion battery according to claim 1 or 2, wherein a conductive layer is provided on the surface of the sodium supplementing material.

5. The positive electrode tab of claim 4 wherein the conductive layer comprises at least one of a carbon material and a conductive polymer.

6. The positive electrode sheet of a sodium ion battery of claim 5, wherein the carbon material comprises at least one of carbon nanotubes, graphene, graphite, carbon black;

7. A positive electrode sheet for a sodium ion battery as defined in claim 5 or 6, wherein the thickness of said conductive layer ranges from 10nm to 300nm.

8. The positive electrode tab of claim 7 wherein the conductive layer has a thickness in the range of 50nm to 200nm.

9. The positive electrode plate of sodium ion battery of claim 4, wherein the conductive layer is entirely coated on the surface of the sodium-supplementing material.

10. A sodium ion battery positive electrode sheet as defined in any one of claims 1, 2, 5, 6, 8, 9, wherein the mass of the sodium-supplementing material is 5% to 15% of the total mass of the active material and the sodium-supplementing material.

11. A method for preparing a sodium supplementing material in a positive electrode sheet of a sodium ion battery as defined in any one of claims 1 to 10, comprising:

drying the first slurry to obtain a first precursor;

mixing the first precursor and an additive containing M2 element, and sintering in inert atmosphere to obtain a sodium supplementing material; the chemical formula of the sodium supplementing material comprises Na _x M1O _4-y M2 _y Wherein x is more than or equal to 2 and less than or equal to 8,0.01, y is more than or equal to 0.35, M1 comprises at least one of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo, and M2 comprises at least one of F, N, P, S.

12. The method for preparing a sodium-supplementing material in a positive electrode sheet of a sodium-ion battery according to claim 11, wherein after the step of mixing the first precursor and the additive containing M2 element and sintering in an inert atmosphere, the method further comprises the steps of:

13. The method for preparing a sodium-supplementing material in a positive electrode sheet of a sodium ion battery according to claim 12, wherein in the step of mixing the obtained sodium-supplementing material with a conductive material and sintering in an inert atmosphere to obtain a conductive material-coated sodium-supplementing material, when the conductive material comprises a carbon material, the sintering temperature is 500 ℃ to 900 ℃ and the time is 6 hours to 12 hours; when the conductive material is a conductive polymer, the sintering temperature is 150-450 ℃ and the sintering time is 4-8 h.

14. The method for producing a sodium-supplementing material in a positive electrode sheet for a sodium-ion battery according to any one of claims 11 to 13, wherein in the step of mixing the first precursor and the additive containing M2 element and sintering in an inert atmosphere, the sintering temperature is 500 ℃ to 900 ℃ and the time is 6 hours to 12 hours.

15. The method for preparing a sodium-supplementing material in a positive electrode sheet of a sodium-ion battery according to any one of claims 11 to 13, wherein in the step of mixing a metal source and a sodium source in a solvent to obtain a first slurry, the method comprises the steps of:

16. The method for producing a sodium-compensating material in a positive electrode sheet of a sodium-ion battery according to any one of claims 11 to 13, wherein in the step of drying the first slurry to obtain a first precursor, comprising the steps of:

17. The method of making a sodium-compensating material in a positive electrode sheet of a sodium ion battery of claim 12 or 13, wherein the metal source comprises one or more of Ni, co, mn, fe, ru, ir, sn, cr, cu, nb, mo powder and metal oxides thereof;

18. An electrode assembly comprising a negative electrode sheet, an electrolyte, and a positive electrode sheet of a sodium ion battery as claimed in any one of claims 1 to 10.

19. A battery comprising the electrode assembly of claim 18.

20. An electrical device comprising the battery of claim 19.