Positive electrode material and preparation method thereof, battery monomer, battery device and power utilization device

Abstract

The invention provides a positive electrode material and a preparation method thereof, a battery monomer, a battery device and a power utilization device. The positive electrode material comprises a sodium transition metal oxide and a silicate material located on the surface of the sodium transition metal oxide, the positive electrode material has the following chemical formula: NaxMyNzO2 / (aNa2O.nSiO2-XrOt.SiO2) b, M comprises one or more of Fe, In, Co, Mn, Ni and Cr, N comprises one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, W, Bi, Sr, Sn, Ga and Al, and X comprises one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn and Sb; 0.58 < = x < = 1.05, 0 < y < = 1, 0 < = z < = 1, 0 < y + z < = 1, 1 / 3 < = r / t < = 2, 1 < = n / a, and 0 < b < = 0.2. The positive electrode material provided by the invention can improve the rate capability and the processability of the battery monomer.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a positive electrode material and its preparation method, a positive electrode sheet, a battery cell, a battery device, and an electrical device. Background Technology

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0003] In the development of battery cells, how to improve the capacity and rate performance of battery cells is one of the urgent problems to be solved. Summary of the Invention

[0004] This application provides a positive electrode material and its preparation method, a battery cell, a battery device, and an electrical device, which can improve the electrolyte retention capacity of the negative electrode of a metal battery cell and improve the cycle performance of the battery cell.

[0005] In a first aspect, this application provides a battery cell, the battery cell including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer including a positive electrode material, wherein the positive electrode material includes a sodium transition metal oxide and a silicate material located on the surface of the sodium transition metal oxide.

[0006] By in-situ introducing silicates onto the surface of sodium transition metal oxides to replace at least a portion of residual alkalis such as carbonates, the sodium ions in silicates, due to their structure and physicochemical properties, can participate at least partially as active sodium ions in the charge-discharge cycle of the battery cell, undergoing insertion / extraction. Furthermore, silicates provide a rapid ion channel for sodium ions, thereby improving the charge-discharge specific capacity of the battery cell. On the other hand, because some sodium ions in silicate materials can participate in the charge-discharge cycle of the battery cell by inserting / extracting into the electrode plates, the electrode plates exhibit lower internal resistance, thus improving the rate performance of the battery cell.

[0007] In some embodiments, the positive electrode material has the following chemical formula: Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) b ,in,

[0008] M includes one or more of Fe, In, Co, Mn, Ni and Cr; N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, W, Bi, Sr, Sn, Ga and Al; and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn and Sb.

[0009] 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, 0<b≤0.2.

[0010] In some embodiments, 0.95 ≤ y + z ≤ 1.

[0011] In some embodiments, 1.25 ≤ n / a ≤ 5.

[0012] In some embodiments, 0.025 ≤ b ≤ 0.1.

[0013] In some embodiments, the phase structure of the cathode material includes one or both of the O3 phase and the P2 phase.

[0014] In some embodiments, the volume distribution particle size Dv50 of the cathode material is 1 μm to 15 μm.

[0015] In some embodiments, the specific surface area of ​​the positive electrode material is 0.1 m². 2 / g to 0.6m 2 / g.

[0016] In some embodiments, the compaction density of the cathode material is 2.8 g / cm³. 3 Up to 3.6 g / cm 3 .

[0017] In some embodiments, the pH of the positive electrode material is 11 to 13.5.

[0018] Secondly, embodiments of this application provide a battery device including a battery cell according to the first aspect of this application.

[0019] Thirdly, embodiments of this application provide an electrical device including a battery according to an embodiment of the second aspect of this application.

[0020] Thirdly, embodiments of this application provide a positive electrode material, comprising a sodium transition metal oxide and a silicate material located on the surface of the sodium transition metal oxide, wherein the positive electrode material has the following chemical formula: Na x M y N z O2 / (aNa2O·nSiO2-X r Ot ·SiO2) b Wherein, M includes one or more of Fe, In, Co, Mn, Ni and Cr, N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, W, Bi, Sr, Sn, Ga and Al, and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn and Sb; 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, 0<b≤0.2.

[0021] In some embodiments, 0.95 ≤ y + z ≤ 1.

[0022] In some embodiments, 1.25 ≤ n / a ≤ 5.

[0023] In some embodiments, 0.025 ≤ b ≤ 0.1.

[0024] In some embodiments, the phase structure of the cathode material includes one or both of the O3 phase and the P2 phase.

[0025] In some embodiments, the volume distribution particle size Dv50 of the cathode material is 1 μm to 15 μm.

[0026] In some embodiments, the specific surface area of ​​the positive electrode material is 0.1 m². 2 / g to 0.6m 2 / g.

[0027] In some embodiments, the compaction density of the cathode material is 2.8 g / cm³. 3 Up to 3.6 g / cm 3 .

[0028] In some embodiments, the pH of the positive electrode material is 11 to 13.5.

[0029] Fourthly, embodiments of this application provide a method for preparing a cathode material, comprising the following steps:

[0030] Based on the chemical formula Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) bProvides a first raw material containing a sodium source, an M element source, and an N element source, and a second raw material containing a silicon source, wherein M includes one or more of Fe, In, Co, Mn, Ni, and Cr; N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, Sr, W, Bi, Sn, Ga, and Al; and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn, and Sb; 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, and 0<b≤0.2;

[0031] The first raw material is subjected to a first sintering treatment to obtain a first sintered material;

[0032] The first sintering material and the second raw material are subjected to a second sintering process to obtain the positive electrode material.

[0033] In some embodiments, the first sintering treatment of the first raw material to obtain the first sintered material includes:

[0034] The first raw material is ball-milled to obtain ball-milled material, and the ball-milled material is then subjected to a first sintering treatment to obtain a first sintered material; wherein...

[0035] The sintering temperature of the first sintering treatment is 850℃ to 1050℃, the sintering time is 8h to 12h, and the heating rate is 3℃ / min to 10℃ / min.

[0036] In some embodiments, the second sintering treatment of the first sintering material and the second raw material to obtain the cathode material includes:

[0037] The first sintering material and the second raw material are ball-milled and mixed, and then subjected to a second sintering treatment to obtain the positive electrode material; wherein,

[0038] The sintering temperature of the second sintering treatment is 850℃ to 1050℃, the sintering time is 8h to 24h, and the heating rate is 3℃ / min to 10℃ / min.

[0039] In some embodiments, the sodium source includes one or more compounds containing sodium.

[0040] In some embodiments, the source of element M includes one or more compounds containing element M.

[0041] In some embodiments, the N source comprises one or more N-containing compounds.

[0042] In some embodiments, the silicon source includes one or more of silicon dioxide, silicic acid, disilicate, metasilicic acid, silicate ester, and ethyl silicate. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of a battery cell provided in some embodiments of this application.

[0045] Figure 2 This is an exploded view of a battery cell provided in some embodiments of this application.

[0046] Figure 3 This is a schematic diagram of a battery module provided in some embodiments of this application.

[0047] Figure 4 This is a schematic diagram of a battery pack provided in some embodiments of this application.

[0048] Figure 5 yes Figure 4 The diagram shown is an exploded view of the battery pack.

[0049] Figure 6 This is a schematic diagram of an electrical device provided in some embodiments of this application.

[0050] The accompanying drawings are not necessarily drawn to scale.

[0051] The reference numerals in the attached diagram are explained as follows: 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Battery cell; 51. Housing; 52. Electrode assembly; 53. Cover plate. Detailed Implementation

[0052] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the electrode assembly, battery cell, battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0053] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, 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 specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0055] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0056] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0057] Unless otherwise specified, the terms "connected" and "linked" in this application should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0058] In this application, "multiple" refers to two or more, including two. "Multiple types" refers to two or more, including two.

[0059] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0060] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0061] A single battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A single battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

[0062] In some embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 2 This is a schematic diagram of battery module 4 as an example. Figure 2 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0063] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0064] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0065] Figure 3 and Figure 4 This is a schematic diagram of battery pack 1 as an example. Figure 3 and Figure 4 As shown, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0066] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0067] The battery cells mentioned in the embodiments of this application may include sodium-ion battery cells.

[0068] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0069] In some embodiments, such as Figure 5 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted according to requirements.

[0070] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0071] Electrode assemblies generally include a positive electrode, a negative electrode, and a separator.

[0072] [Positive electrode plate]

[0073] The positive electrode may include a positive current collector and a positive electrode film layer located on at least one side of the surface of the positive current collector, the positive electrode film layer containing a positive electrode material.

[0074] In some embodiments, the cathode material includes a sodium transition metal oxide and a silicate material located on the surface of the sodium transition metal oxide.

[0075] Sodium transition metal oxides generally exhibit high levels of residual alkali on their surface. This residual alkali primarily originates from carbonates or hydroxides generated during the sintering process of sodium transition metal oxides through alkali metal reactions, such as sodium carbonate, potassium carbonate, and sodium hydroxide. These residual alkalis adhere to the surface of the sodium transition metal oxides. Since elements such as sodium in the residual alkalis are inorganic salts, sodium ions are difficult to participate in the charging and discharging process as active sodium in the electrode, resulting in fewer sodium ions available for charge-discharge cycles in the battery cell and consequently, a decrease in the capacity of the cathode material. Simultaneously, the presence of residual alkali on the surface increases the electrode surface resistance, leading to an increase in the internal resistance of the battery cell and affecting its rate performance.

[0076] By in-situ introducing silicates onto the surface of sodium transition metal oxides to replace at least a portion of residual alkalis such as carbonates, the sodium ions in silicates, due to their structure and physicochemical properties, can participate at least partially as active sodium ions in the charge-discharge cycle of the battery cell, undergoing insertion / extraction. Furthermore, silicates provide a rapid ion channel for sodium ions, thereby improving the charge-discharge specific capacity of the battery cell. On the other hand, because some sodium ions in silicate materials can participate in the charge-discharge cycle of the battery cell by inserting / extracting into the electrode plates, the electrode plates exhibit lower internal resistance, thus improving the rate performance of the battery cell.

[0077] In addition, during the heat treatment of sodium transition metal oxides, some alkali metal elements other than Na on the surface can also form corresponding silicate structures with silicates, thereby affecting the surface structure of sodium transition metal oxides and thus affecting the electrochemical performance of the material.

[0078] In some embodiments, the cathode material may have the following chemical formula: Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) b Wherein, M may include one or more of Fe, In, Co, Mn, Ni and Cr, N may include one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, Sr, W, Bi, Sn, Ga and Al, and X may include one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn and Sb; 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, 0<b≤0.2.

[0079] In this embodiment, the silicate material on the surface of the sodium transition metal oxide may include other silicates besides sodium silicate, which can be formed by the reaction of other doping elements in the sodium transition metal oxide. In the above chemical formula, when X is Na, it indicates that the silicate material on the surface of the sodium transition metal oxide is only sodium silicate.

[0080] The surface silicates of cathode materials can be detected by scanning transmission electron microscopy (STEM). By detecting the phase structure on the surface of cathode material particles, it can be determined whether Si and other metal elements are present. Furthermore, the surface phase structure can be used to determine whether Si and the corresponding metal elements belong to the same pure substance, thereby detecting the type of silicate generated and the corresponding element ratio.

[0081] Optionally, 0.025 ≤ b ≤ 0.1. For example, the value of b can be 0.01, 0.015, 0.02, 0.025, 0.03, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or a range of any of the above values.

[0082] b reflects the proportion of silicate material relative to sodium transition metal oxide in the cathode material. Introducing a certain amount of silicate in situ onto the surface of sodium transition metal oxide can reduce the impact of residual alkali on the electrochemical performance of the battery cell, resulting in higher charge-discharge specific capacity and improved rate performance. However, Si in silicate is a non-variable valence element and does not possess reversible electrochemical properties. Excessive Si content can negatively affect the electrochemical performance of the battery cell, leading to a decrease in charge-discharge specific capacity and cycle performance. Therefore, limiting the value of b within the aforementioned range is beneficial for improving the electrochemical performance of the battery cell.

[0083] In the above chemical formula, 1 ≤ n / a, optionally, 1.25 ≤ n / a ≤ 5, and more preferably, 1.5 ≤ n / a ≤ 4.

[0084] n / a reflects the modulus of silicon in sodium silicate, i.e., the silicon content in the silicate structure formed by silicon and sodium metal oxide. When n / a is too small, the silicon content in the silicate structure is low, limiting its effectiveness in improving the residual alkali on the sodium transition metal oxide surface and hindering the improvement of the cathode material's electrochemical performance. Conversely, when n / a is large, the relative molecular mass of the silicate material increases, resulting in a higher silicon content, which is also detrimental to improving the cathode material's electrochemical performance. Therefore, by limiting the n / a value within the aforementioned range, the specific capacity and rate performance of individual battery cells can be better improved.

[0085] In some embodiments, 0.95 ≤ y + z ≤ 1. y + z can reflect the content of transition metal elements in the sodium transition metal oxide. By limiting the value of y + z to the above range, a sodium transition metal oxide with a stable structure can be obtained, giving the cathode material good electrochemical performance.

[0086] In some embodiments, as an example, the cathode material may include, but is not limited to, Na[Ni]. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2] 0.9 [Cu 0.5 Ti 0.5 ] 0.1 O2 / (Na2O·2SiO2) 0.02 Na[Ni 1 / 3 Fe 1 / 3 Mn 1 / 3 O2] 0.9 [Ca 0.5 Ti 0.5 ] 0.1 O2 / (Na2O·2SiO2-CaO·SiO2) 0.02 Na[Ni 1 / 3 Fe 1 / 3 Mn 1 / 3 O2] 0.9 [Al 0.2 Mg 0.4 Ti 0.4 ] 0.1 O2 / (Na2O·2SiO2-MgO·SiO2-Al2O3·3SiO2) 0.02 One or more of them.

[0087] In some embodiments, the phase structure of the cathode material includes one or both of the O3 and P2 phases. The cathode material has the same phase structure as the sodium transition metal oxide, which indicates that the in-situ introduction of silicate material on the surface of the sodium transition metal oxide does not change the crystal phase structure of the material and can well utilize the electrochemical performance of the sodium transition metal oxide.

[0088] In some embodiments, the volumetric particle size Dv50 of the cathode material can be from 1 μm to 15 μm, optionally from 2.5 μm to 14 μm, and more preferably from 5 μm to 12 μm. A Dv50 within the above range can shorten the migration path of active ions in the cathode material particles and facilitate the formation of a smooth porous structure in the cathode film. This allows the cathode electrode to possess good active ion migration rate and electrolyte transport performance, which is beneficial for further improving the electrochemical performance of the battery cell.

[0089] The volumetric distribution particle size Dv50 of a material has a well-known meaning in the art, representing the particle size corresponding to a cumulative volume distribution percentage of 50%, and can be determined using instruments and methods known in the art. For example, it can be determined using a laser particle size analyzer, referring to GB / T19077-2016.

[0090] In some embodiments, the specific surface area of ​​the cathode material is 0.1 m². 2 / g to 0.6m 2 / g, can be selected as 0.2m 2 / g to 0.5m 2 / g, or 0.25m 2 / g to 0.4m 2 / g.

[0091] Specific surface area refers to the total area per unit mass of material. When the specific surface area of ​​the cathode material falls within the aforementioned range, the active material can provide more ion adsorption sites, further enhancing the transport rate of active ions in the cathode film and the wettability of the electrode solution, thus giving the cathode material superior electrochemical performance. Specific surface area can be determined using methods known in the art, for example, according to the methods and instruments specified in GB / T 19587-2017.

[0092] In some embodiments, the compaction density of the cathode material is 2.8 g / cm³. 3 Up to 3.6 g / cm 3 2.9g / cm³ is an option. 3 Up to 3.5g / cm 3 Alternatively, a 3.0g / cm³ option is available. 3 Up to 3.3 g / cm 3 When the compaction density of the cathode material is within the above range, it can ensure close contact between particles in the cathode film layer and form good electrolyte wetting channels, thereby improving the fast charging performance and cycle performance of the battery cell.

[0093] Compacted density is a term well-known in the art and can be determined using methods already established in the field. For example, it can be determined using an electronic pressure testing machine, referring to GB / T 24533-2009. In this embodiment, the compacted density is measured at a pressure of 3 tons.

[0094] In some embodiments, the pH of the cathode material is between 11 and 13.5. The pH of the cathode material can be measured using methods known in the art. A pH within the above range provides better compatibility between the cathode material and the binder, which is beneficial for the preparation of the electrode slurry and can improve the processing performance of the cathode material.

[0095] In some embodiments, the positive electrode material may further include one or more of the sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds, which are different from those described in this application. The sodium-ion battery of this application embodiment can employ a negative electrode sheet with hard carbon as the negative electrode active material, combined with a positive electrode sheet comprising one or more of the positive electrode active materials selected from sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds, thereby enabling the sodium-ion battery to possess high capacity performance and energy density.

[0096] Examples of the aforementioned sodium transition metal oxides include:

[0097] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0098] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 It is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0099] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,

[0100] 0.67 <d+e<0.8,b+c+d+e=1。

[0101] Examples of the aforementioned polyanionic compounds include:

[0102] A 1 f M 3 g (PO4) i O j X 13-j , where A is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0103] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0104] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0105] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example t is 0, 1, 1.5, 2, or 3.

[0106] As an example of the above Prussian blue compounds, for example, the following can be listed:

[0107] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + , NH4 + , an alkali metal cation, and an alkaline earth metal cation, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+、Sr 2+ Ba 2+ and Ra 2+ One or more of them, M 6 and M 7 Each is an independently selected cation of one or more transition metal elements chosen from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W. Optionally, A is Li. + Na + and K + One or more of them, M 6 It is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu, M 7 It is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni and Cu.

[0108] The modified compounds for the above-mentioned cathode materials can be obtained by doping and / or surface coating of the cathode materials.

[0109] In some embodiments, the positive electrode film may optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0110] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0111] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a first layer of polymeric material and a layer of metallic material formed on at least one surface of the first layer of polymeric material. As an example, the metallic material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the first layer of polymeric material may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0112] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0113] This application also provides a method for preparing a cathode material, including the following steps:

[0114] S100, based on the chemical formula Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) b Provides a first raw material containing a sodium source, an M element source, and an N element source, and a second raw material containing a silicon source, wherein M includes one or more of Fe, In, Co, Mn, Ni, and Cr; N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, Sr, W, Bi, Sn, Ga, and Al; and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn, and Sb; 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, and 0<b≤0.2;

[0115] S200, the first raw material is subjected to a first sintering treatment to obtain the first sintered material;

[0116] S300 involves a second sintering process, in which the first sintering material and the second raw material are subjected to a second sintering process to obtain the cathode material.

[0117] According to the preparation method of this application embodiment, the cathode material is first prepared by sintering sodium transition metal oxide. During the sintering process, residual alkali is formed on the surface of the sodium transition metal oxide. During the second sintering process with the addition of a silicon source, the silicon source reacts with the residual alkali on the surface of the sodium transition metal oxide to generate silicate, thereby introducing silicate material in situ into the sodium transition metal oxide, reducing the amount of residual alkali on the surface of the sodium transition metal oxide, and improving the electrochemical performance of the cathode material. Therefore, the above preparation method can be used to prepare the cathode material in the embodiments of this application.

[0118] In some embodiments, step S200 may include: ball milling a first raw material to obtain ball milling material, and performing a first sintering treatment on the ball milling material to obtain a first sintered material.

[0119] In some embodiments, the sintering temperature of the first sintering treatment can be from 850°C to 1050°C. Exemplarily, the sintering temperature of the first sintering treatment can be 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, or any range of the above values.

[0120] In some embodiments, the holding sintering time of the first sintering treatment can be from 8 hours to 12 hours. For example, the holding sintering time of the first sintering treatment can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or any range of the above values.

[0121] In some embodiments, the heating rate of the first sintering process can be from 3°C / min to 10°C / min. Exemplarily, the heating rate of the first sintering process can be 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range of the above values.

[0122] In some embodiments, step S30 may include: mixing the first sintering material with the second raw material through ball milling and then performing a second sintering process to obtain a cathode material.

[0123] In some embodiments, the sintering temperature of the second sintering treatment can be from 850°C to 1050°C. Exemplarily, the sintering temperature of the second sintering treatment can be 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, or any range of the above values.

[0124] In some embodiments, the sintering time of the second sintering treatment can be from 8 hours to 24 hours. For example, the holding sintering time of the first sintering treatment can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, or any range of the above values.

[0125] In some embodiments, the heating rate of the second sintering process can be from 3°C / min to 10°C / min. Exemplarily, the heating rate of the second sintering process can be 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range of the above values.

[0126] In some embodiments, the sodium source may include one or more compounds containing sodium. For example, the sodium source may include one or more sodium salts, sodium oxides, and sodium hydroxides. As an example, the sodium source may be one or more of Na₂CO₃, NaHCO₃, NaOH, and Na₂O₂.

[0127] In some embodiments, the source of element M may include one or more compounds containing element M, optionally one or more of oxides containing element M, salts containing element M, and hydroxides containing element M.

[0128] In some embodiments, the N source may include one or more N-containing compounds, optionally one or more N-containing oxides, N-containing salts, and N-containing hydroxides.

[0129] In some embodiments, the silicon source may include one or more of silicon dioxide, silicic acid, disilicate, metasilicic acid, silicate ester, and ethyl silicate.

[0130] [Negative electrode plate]

[0131] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0132] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector can be made of materials such as metal foil, carbon-coated metal foil, or porous metal plate, and copper foil is an option.

[0133] As an example, the negative electrode film layer includes a negative electrode active material, an optional conductive agent, and an optional binder. The conductive agent is used to improve the conductivity of the negative electrode film layer, and the binder is used to firmly bond the negative electrode active material and the binder to the negative electrode current collector. This application does not specifically limit the types of conductive agents and binders, which can be selected according to actual needs.

[0134] As an example, the negative electrode active material can be one or more of natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, and soft carbon.

[0135] As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; the binder may be one or more of styrene-butadiene rubber (SBR), styrene-butadiene rubber (SBCs), water-based acrylic resin, and carboxymethyl cellulose (CMC).

[0136] The negative electrode film may also optionally include a thickener, such as carboxymethyl cellulose (CMC). However, this application is not limited to this, and other materials that can be used as thickeners for the negative electrode sheet of sodium-ion batteries may also be used.

[0137] [Isolation membrane]

[0138] The separator is located between the positive and negative electrodes and mainly serves to prevent internal short circuits.

[0139] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0140] In some embodiments, the material of the separator may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0141] [Electrolytes]

[0142] A single battery cell includes an electrolyte. The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid-state.

[0143] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0144] In some embodiments, the electrolyte includes anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI-), bis(oxalato)borate anion (BOB-), bis(fluoro)oxalato)borate anion (DFOB-), bis(fluoro)dioxalato)phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP-), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) - ), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6)- ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0145] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0146] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0147] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0148] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, 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), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0149] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0150] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained.

[0151] This application also provides an electrical device, which includes the battery device provided in this application. The battery device can be used as the power source for the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as 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.

[0152] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0153] Figure 6 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0154] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0155] Example

[0156] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0157] Test section

[0158] 1. Processing performance of cathode materials

[0159] The positive electrode material, conductive agent Super P, binder polyvinylidene fluoride (PVDF), and solvent N-methylpyrrolidone (NMP) were mixed at a weight ratio of 85:15:5:49 and stirred continuously for 5 minutes to obtain a slurry. The slurry was then allowed to stand and observed to see if gelation or solidification occurred. The following methods were used to determine whether gelation or solidification occurred:

[0160] If the slurry gels or solidifies within 4 hours of standing, it is rated as poor.

[0161] If gelation or solidification occurs within 4 to 12 hours of standing, the evaluation is moderate.

[0162] The slurry does not show any gelation or solidification within 12 hours of standing, and is rated as excellent.

[0163] 2. Discharge specific capacity

[0164] At 25°C, a single battery cell is charged to 4.2V at a constant current density of 1mA / g, and then discharged to 2.5V at a constant current density of 1mA / g. Calculate the ratio of charging capacity to discharging capacity.

[0165] 3. Ratio performance

[0166] At 25°C, a single battery cell is charged to 4.2V at a constant current density of 1mA / g, and then discharged to 1.5V at a constant current density of 1mA / g. The resulting specific capacity is the 0.1C discharge-to-1.5V specific capacity. At 25°C, the coin cell sodium-ion battery corresponding to Example 1 is charged to 4.2V at a constant current density of 10mA / g, and then discharged to 1.5V at a constant current density of 10mA / g. The resulting specific capacity is the 1C discharge-to-1.5V specific capacity. The 1C / 0.1C rate is calculated by the ratio of the 1C discharge specific capacity to the 0.1C discharge specific capacity.

[0167] 4. Residual alkali test

[0168] According to standard GB / T 9736-2008, general methods for determining the acidity and alkalinity of chemical reagents:

[0169] Pretreatment: Weigh 30g of sample powder, add 100ml of pure water and stir for 30min, let stand for 10min, filter and transfer a certain amount of filtrate.

[0170] Test: Using 0.05 mol / L hydrochloric acid standard solution, air bubbles were removed from the burette. The corresponding sensor and program were selected to start automatic detection, obtaining the Na2CO3 content (w / w%), NaOH content (w / w%), and total Na2CO3 content. + Content (mass fraction w / w%).

[0171] Example 1

[0172] Preparation of cathode materials

[0173] S100, according to the molar ratio of Na:M:Cu:Sn:Mg:Al = 1:0.8:0.1:0.02:0.04:0.04, weigh the raw material Na2CO3 and the spherical precursor M(Ni) 0.2 Fe 0.4 Mn 0.4 30g of CuO, SnO2, MgO, and Al2O3 were pre-ground and mixed in an agate mortar and then put into a planetary ball mill for ball milling to obtain a precursor mixture.

[0174] S200: The obtained precursor mixture is uniformly loaded into an open crucible and placed in a muffle furnace. The temperature is increased from room temperature to 900°C at a rate of 5°C / min, and then kept at 900°C for 12 hours. After that, it is naturally cooled to room temperature.

[0175] The sample obtained in step S20 was tested according to the residual alkali detection method to obtain the total Na on the surface. + The content was determined by testing the total Na content on the surface of the cathode material. + The content is 0.2327 wt%, and the amount of Si added is based on the total Na on the surface of the cathode material. + The amount added should be based on the number of moles of silicate that can be generated from the content.

[0176] S300: The sample obtained in step S200 is mixed and ground with SiO2 at a molar ratio of 1:0.012. The ground mixture is uniformly placed in an open crucible and placed in a muffle furnace. The temperature is increased from room temperature to 900°C at a heating rate of 5°C / min and kept at 900°C for 6 hours. Then, it is naturally cooled to room temperature. The obtained sample is ground to obtain the positive electrode material.

[0177] Preparation of positive electrode sheet

[0178] The obtained positive electrode material, conductive agent Super P, binder polyvinylidene fluoride (PVDF), and solvent N-methylpyrrolidone (NMP) are ground and mixed evenly in a mass ratio of 80:15:5:100 to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0179] Negative electrode sheet

[0180] A negative electrode slurry is prepared by uniformly mixing hard carbon (anode material), Super P (conductive agent), sodium carboxymethyl cellulose (CMC) (binder), and water (solvent) in a mass ratio of 80:10:10:100. The negative electrode slurry is then uniformly coated onto the surface of copper foil (current collector), and subsequently dried, cooled, and slit to obtain the negative electrode sheet.

[0181] Separating membrane

[0182] A polypropylene (PP) film with a thickness of 12μm was selected.

[0183] electrolyte

[0184] The electrolyte is NaClO4 dissolved in an organic solvent with a volume ratio of ethylene carbonate (EC): diethyl carbonate (DEC) of 1:1, the concentration of NaClO4 is 1 mol / L, and 5% by mass of fluoroethylene carbonate is added as a film-forming additive.

[0185] battery cell

[0186] After cutting the positive electrode, separator, and negative electrode to appropriate sizes, stack them in order, with the separator positioned between the positive and negative electrodes. Then, inject electrolyte and seal the container. After standing, a button cell is obtained.

[0187] Examples 2 to 10

[0188] The difference from Example 1 is that the chemical composition of the positive electrode material is different, as detailed in Table 1. All other aspects are consistent with Example 1.

[0189] Example 11

[0190] The preparation method of the positive electrode material differs from that in Example 1, specifically as follows:

[0191] S100, Na2CO3, and spherical precursor M(Ni) 0.2 Fe 0.4 Mn 0.4 CuO, SnO2, MgO, Al2O3, and silicon dioxide were pre-ground and mixed in an agate mortar and then fed into a planetary ball mill for ball milling to obtain a precursor mixture; wherein, the proportions of each raw material were the same as in Example 1.

[0192] S200: The obtained precursor mixture is uniformly loaded into an open crucible and placed in a muffle furnace. The temperature is increased from room temperature to 900°C at a rate of 5°C / min, and then kept at 900°C for 12 hours. After that, the temperature is naturally cooled to room temperature. The obtained sample is ground to obtain the cathode material.

[0193] Comparative Examples 1 to 3

[0194] The difference from Example 1 is that the chemical composition of the positive electrode material is different, as detailed in Table 1. All other aspects are consistent with Example 1.

[0195] The performance test data is shown in Table 1.

[0196]

[0197] As can be seen from the data in Table 1, in the embodiments of this application, by introducing silicates in situ on the surface of sodium transition metal oxides to replace at least part of the residual alkalis such as carbonates, the impact of residual alkalis on the performance of the cathode material can be reduced, and the rate performance and processing performance of the battery cells can be effectively improved.

[0198] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer comprising a positive electrode material, wherein... The cathode material includes a sodium transition metal oxide and a silicate material located on the surface of the sodium transition metal oxide.

2. The battery cell according to claim 1, characterized in that, The cathode material has the following chemical formula: Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) b ,in, M includes one or more of Fe, In, Co, Mn, Ni and Cr; N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, W, Bi, Sr, Sn, Ga and Al; and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn and Sb. 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, 0<b≤0.

2.

3. The battery cell according to claim 2, characterized in that, 0.95≤y+z≤1.

4. The battery cell according to claim 2 or 3, characterized in that, 1.25≤n / a≤5.

5. The battery cell according to any one of claims 2 to 4, characterized in that, 0.025≤b≤0.1。 6. The battery cell according to any one of claims 1 to 5, characterized in that, The cathode material satisfies at least one of the following conditions: (1) The phase structure of the cathode material includes one or both of the O3 phase and the P2 phase; (2) The volume distribution particle size Dv50 of the positive electrode material is 1 μm to 15 μm; (3) The specific surface area of ​​the positive electrode material is 0.1 m². 2 / g to 0.6m 2 / g; (4) The compaction density of the positive electrode material is 2.8 g / cm³. 3 Up to 3.6 g / cm 3 ; (5) The pH of the positive electrode material is 11 to 13.

5.

7. A battery device comprising a battery cell as described in any one of claims 1 to 6.

8. An electrical device comprising the battery device of claim 7.

9. A positive electrode material, characterized in that, It includes sodium transition metal oxide and silicate material located on the surface of the sodium transition metal oxide.

10. The cathode material according to claim 9, characterized in that, The cathode material has the following chemical formula: Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) b ,in, M includes one or more of Fe, In, Co, Mn, Ni and Cr; N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, W, Bi, Sr, Sn, Ga and Al; and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn and Sb. 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, 0<b≤0.

2.

11. The cathode material according to claim 10, characterized in that, 0.95≤y+z≤1.

12. The cathode material according to claim 10 or 11, characterized in that, 1.25≤n / a≤5.

13. The cathode material according to any one of claims 10 to 12, characterized in that, 0.025≤b≤0.1。 14. The cathode material according to any one of claims 9 to 13, characterized in that, The cathode material satisfies at least one of the following conditions: (1) The phase structure of the cathode material includes one or both of the O3 phase and the P2 phase; (2) The volume distribution particle size Dv50 of the positive electrode material is 1 μm to 15 μm; (3) The specific surface area of ​​the positive electrode material is 0.1 m². 2 / g to 0.6m 2 / g; (4) The compaction density of the positive electrode material is 2.8 g / cm³. 3 Up to 3.6 g / cm 3 ; (5) The pH of the positive electrode material is 11 to 13.

5.

15. A method for preparing a positive electrode material, characterized in that, Includes the following steps: Based on the chemical formula Na x M y N z O2 / (aNa2O·nSiO2-X r O t ·SiO2) b Provides a first raw material containing a sodium source, an M element source, and an N element source, and a second raw material containing a silicon source, wherein M includes one or more of Fe, In, Co, Mn, Ni, and Cr; N includes one or more of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, Sr, W, Bi, Sn, Ga, and Al; and X includes one or more of Na, Li, K, Mg, Ca, Zn, Al, Cr, Sr, Sn, and Sb; 0.58≤x≤1.05, 0<y≤1, 0≤z≤1, 0<y+z≤1, 1 / 3≤r / t≤2, 1≤n / a, and 0<b≤0.2; The first raw material is subjected to a first sintering treatment to obtain a first sintered material; The first sintering material and the second raw material are subjected to a second sintering process to obtain the positive electrode material.

16. The preparation method according to claim 15, characterized in that, The step of subjecting the first raw material to a first sintering treatment to obtain a first sintered material includes: The first raw material is ball-milled to obtain ball-milled material, and the ball-milled material is then subjected to a first sintering treatment to obtain a first sintered material; wherein... The sintering temperature of the first sintering treatment is 850℃ to 1050℃, the sintering time is 8h to 12h, and the heating rate is 3℃ / min to 10℃ / min.

17. The preparation method according to claim 15, characterized in that, The step of performing a second sintering treatment on the first sintering material and the second raw material to obtain the positive electrode material includes: The first sintering material and the second raw material are ball-milled and mixed, and then subjected to a second sintering treatment to obtain the positive electrode material; wherein, The sintering temperature of the second sintering treatment is 850℃ to 1050℃, the sintering time is 8h to 24h, and the heating rate is 3℃ / min to 10℃ / min.

18. The preparation method according to any one of claims 15 to 17, characterized in that, The first raw material satisfies at least one of the following conditions: (1) The sodium source includes one or more compounds containing sodium; (2) The source of element M includes one or more compounds containing element M; (3) The N source includes one or more compounds containing N.

19. The preparation method according to any one of claims 15 to 18, characterized in that, The silicon source includes one or more of silicon dioxide, silicic acid, disilicate, metasilicic acid, silicate ester, and ethyl silicate.

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