Composite lithium-supplementing material and preparation method therefor, positive electrode sheet, battery and electric device

Abstract

A composite lithium-supplementing material and a preparation method therefor, a positive electrode sheet, a battery and an electric device. The composite lithium-supplementing material comprises: a porous carrier and a lithium-supplementing agent, wherein the porous carrier is a nitrogen-doped porous carbon carrier, and a transition metal compound is present on the inner surface of pore structures of the porous carrier; and the lithium-supplementing agent is located inside the pores of the porous carrier.

Description

Composite lithium supplement material and preparation method thereof, positive electrode sheet, battery, and electrical device Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a composite lithium-supplementing material, a method for preparing the composite lithium-supplementing material, a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high energy density, long cycle life, and good rate performance. Therefore, how to further improve the energy density and cycle life of lithium-ion batteries is a research hotspot in the battery field. On the one hand, the reversible specific capacity of the currently widely used positive electrode active materials is already at a high level. Further improvement of the specific capacity of the positive electrode active materials is likely to cause the collapse of the structure of the positive electrode active materials themselves, thereby leading to a significant decrease in cycle performance. On the other hand, lithium loss during the battery charge and discharge process is the main reason for the attenuation of battery capacity and energy density. Pre-lithiation of the battery can replenish the lithium source consumed during the battery charge and discharge process, thereby improving the battery's energy density and cycle life. However, the current pre-lithiation treatment is still in its early development stage and still has many shortcomings in industrial production and application.

[0003] It should be noted that the above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art.

[0004] Application Contents

[0005] In its first aspect, this application proposes a composite lithium-supplementing material comprising: a porous carrier, the porous carrier being a nitrogen-doped porous carbon carrier, wherein a transition metal compound is present on the inner surface of the pore structure of the porous carrier; and a lithium-supplementing agent, the lithium-supplementing agent being located within the pores of the porous carrier. This allows for a lithium-supplementing agent with a smaller particle size, a lower decomposition voltage, and better electrical conductivity, thereby providing a composite lithium-supplementing material with superior lithium-supplementing performance.

[0006] In some embodiments, the transition metal compound includes at least one of a transition metal carbide, a transition metal nitride, a transition metal phosphide, a transition metal oxide, a transition metal sulfide, and a transition metal selenide, thereby effectively reducing the decomposition voltage of the lithium supplement.

[0007] In some embodiments, the transition metal compound is in contact with the lithium supplement agent, thereby enhancing the catalytic effect of the transition metal compound on the lithium supplement agent's decomposition and lithium release reaction.

[0008] In some embodiments, the mass fraction of the transition metal in the porous carrier is 10%-50%, thereby improving the catalytic effect of the transition metal compound on the decomposition and lithium release reaction of the lithium supplement agent.

[0009] In some embodiments, the particle size of the transition metal compound is 10 nm to 200 nm. Thus, the transition metal compound can fully contact with the lithium supplement agent, thereby reducing the decomposition voltage of the lithium supplement agent.

[0010] In some embodiments, the transition metal compound satisfies the chemical formula M a X b , wherein M includes at least one of Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, and Ta, and X includes at least one of C, N, P, O, S, and Se; 0<a≤3, 0≤b≤4. This effectively reduces the decomposition voltage of the lithium supplement.

[0011] In some embodiments, the porous carrier satisfies at least one of the following conditions: a Dv50 particle size of 1 μm to 20 μm; a porosity of 20% to 60%; and an average pore size of 1 nm to 100 nm. This allows for the production of a lithium supplement with smaller particle size and higher uniformity.

[0012] In some embodiments, the composite lithium-supplementing material satisfies at least one of the following conditions: a nitrogen content of 0.5% to 5%; a carbon content of 0.5% to 5%; or a carbon content of 2% to 30%. This improves the conductivity of the composite lithium-supplementing material.

[0013] In some embodiments, the Dv50 particle size of the composite lithium-supplementing material is 1 μm to 30 μm, thereby improving the utilization efficiency of the composite lithium-supplementing material.

[0014] In some embodiments, the Dv50 particle size of the composite lithium-supplementing material is 1 μm to 20 μm, thereby further improving the utilization efficiency of the composite lithium-supplementing material.

[0015] In some embodiments, the particle size of the lithium supplement agent is 5 nm to 100 nm, thereby increasing the reaction sites of the lithium supplement agent and shortening the transmission path of electrons and ions.

[0016] In some embodiments, the lithium supplement agent includes at least one of Li2C2O4, Li2C4O4, Li2C3O5, Li2C4O6, Li2C2O2N4, Li2O, Li2O2, Li2S, and LiF. Thus, the lithium supplement effect of the lithium supplement agent can be improved.

[0017] In some embodiments, the lithium supplement agent includes at least one of Li2C2O4, Li2C4O4, Li2C3O5, Li2C4O6, and Li2C2O2N4. This can further improve the lithium supplement effect of the lithium supplement agent.

[0018] In a second aspect of the present application, the present application proposes a method for preparing a composite lithium supplement material, comprising: providing a Prussian blue analogue, wherein the Prussian blue analogue satisfies the chemical formula: M1 c [M2 d (CN)6] e , wherein M1 and M2 independently comprise transition metal elements, 0 < c ≤ 4, 0 < d ≤ 4, and 0 < e ≤ 3; a Prussian blue analog is heat-treated to obtain a porous support, wherein the porous support is a nitrogen-doped porous carbon support, and a transition metal compound is present on the inner surface of the pore structure of the porous support; the porous support is dissolved in a lithium supplement agent solution and dried to obtain the composite lithium supplement material. Thus, the lithium supplement agent can be formed within the pore structure of the porous support through a simple method, thereby obtaining a lithium supplement agent with a smaller particle size, better conductivity, and lower decomposition voltage, thereby obtaining a composite lithium supplement material with excellent lithium supplement performance.

[0019] In some embodiments, providing a Prussian blue analogue comprises: adding M1 metal salt and sodium citrate to water to obtain a first solution; d (CN)6] is added to water to obtain a second solution; the first solution and the second solution are simultaneously added dropwise to the solvent and stirred to react to obtain the Prussian blue analog M1 c [M2 d (CN)6] e .

[0020] In some embodiments, M1 and M2 independently include at least one of Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, and Ta. Thus, the decomposition voltage of the lithium supplement can be reduced by adding transition metals.

[0021] In some embodiments, the drying process includes a recrystallization process, thereby volatilizing the solvent of the lithium supplementing agent solution, so that the solvent lithium supplementing agent is deposited in the pores of the porous carrier.

[0022] In some embodiments, the recrystallization process satisfies at least one of the following conditions: a temperature of 60°C to 100°C; a rotation speed of 500 rpm to 1000 rpm; and a stirring time of 1 to 5 hours. This can further improve the particle size uniformity and recrystallization yield of the lithium supplement.

[0023] In some embodiments, the heat treatment satisfies at least one of the following conditions: the heat treatment atmosphere comprises at least one of air, oxygen, nitrogen, argon, phosphine, hydrogen sulfide, sulfur vapor, and selenium vapor; the heat treatment temperature is 300°C to 1000°C; and the heat treatment time is 1 hour to 6 hours. Thus, a variety of transition metal compounds with excellent catalytic properties can be obtained.

[0024] In some embodiments, the heat treatment satisfies at least one of the following conditions: the heat treatment atmosphere includes at least one of air and oxygen, and the heat treatment temperature is 300°C-700°C; the heat treatment atmosphere includes at least one of nitrogen and argon, and the heat treatment temperature is 600°C-1000°C; the heat treatment atmosphere includes phosphine, and the heat treatment temperature is 300°C-600°C; the heat treatment atmosphere includes at least one of sulfur vapor and selenium vapor, and the heat treatment temperature is 400°C-800°C. Thus, transition metal compounds such as transition metal carbides, transition metal nitrides, transition metal phosphides, transition metal oxides, transition metal sulfides, and transition metal selenides can be obtained.

[0025] In some embodiments, the lithium supplement solution satisfies at least one of the following conditions: the mass concentration of the lithium supplement solution is 1%-10%; and the solvent of the lithium supplement solution includes water. This can improve the effect of recrystallization.

[0026] In some embodiments, the heat treatment further comprises: mixing the Prussian blue analogue with a carbon source to obtain a mixture, and subjecting the mixture to the heat treatment, thereby improving the conductivity of the composite lithium supplementing material.

[0027] In some embodiments, the carbon source includes at least one of melamine, dicyandiamide, glucose, sodium citrate, vitamin C, polyvinyl alcohol, polypyrrole, and polyethylene glycol, thereby further improving the conductivity of the composite lithium supplement material.

[0028] In some embodiments, the mass of the Prussian blue analog in the mixture is m1, the mass of the carbon source in the mixture is m2, and the ratio of m1:m2 is 100:(10-40). This can further improve the conductivity of the composite lithium-supplementing material without reducing the specific capacity of the composite lithium-supplementing material.

[0029] In a third aspect, the present application provides a positive electrode sheet comprising a positive current collector and a positive electrode active material layer located on at least one surface of the positive current collector, wherein the positive electrode active material layer comprises the aforementioned composite lithium-supplementing material and / or a composite lithium-supplementing material prepared using the aforementioned method. Thus, the positive electrode sheet possesses all the features and advantages of the aforementioned composite lithium-supplementing material and the method for preparing the composite lithium-supplementing material, which will not be further elaborated here.

[0030] In some embodiments, the positive electrode active material layer further includes a positive electrode active material, the mass of the composite lithium supplementing material in the positive electrode active material layer is m3, the mass of the positive electrode active material in the positive electrode active material layer is m4, and the ratio of m3:m4 is (0.5-20):100. Thus, a battery using this positive electrode sheet has a higher energy density and a longer cycle life.

[0031] In some embodiments, m3:m4 is (1-10): 100. Thus, a battery using the positive electrode sheet has both excellent energy density and cycle life.

[0032] In a fourth aspect of the present application, the present application provides a battery comprising the aforementioned positive electrode sheet. Thus, the battery has all the features and advantages of the aforementioned positive electrode sheet, which will not be described in detail here.

[0033] In a fifth aspect of the present application, the present application provides an electrical device comprising the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0035] FIG1 is a schematic structural diagram of a composite lithium supplement material according to an embodiment of the present application;

[0036] FIG2 is a schematic flow diagram of a method for preparing a composite lithium supplement material according to an embodiment of the present application;

[0037] FIG3 is a schematic flow diagram of a method for preparing a composite lithium supplement material according to another embodiment of the present application;

[0038] FIG4 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0039] FIG5 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG4 ;

[0040] FIG6 is a schematic diagram of a battery module according to an embodiment of the present application;

[0041] FIG7 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0042] FIG8 is an exploded view of the battery pack shown in FIG7 according to an embodiment of the present application;

[0043] FIG9 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0044] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 housing; 52 electrode assembly; 53 top cover assembly; 100: porous carrier; 110: transition metal compound; 200: lithium supplement. DETAILED DESCRIPTION

[0045] Below, with appropriate reference to the accompanying drawings, the embodiments of the composite lithium supplement material, the method for preparing the composite lithium supplement material, the positive electrode sheet, the battery, and the electrical device of the present application are specifically disclosed in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0046] " scope " disclosed in the application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 are listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] In the description of this application, regardless of whether the word "about" or "approximately" is used, all numbers disclosed herein are approximate values. The value of each number may vary by less than 10% or by a reasonable difference considered by a person skilled in the art, such as 1%, 2%, 3%, 4% or 5%.

[0048] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0049] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0050] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0051] In the description of this application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for example, and may be any technical feature connected by "and / or" in this application.

[0052] During the first charge and discharge process of the battery, the electrolyte will undergo a reduction decomposition reaction on the surface of the negative electrode and form a solid electrolyte interface film (SEI film). The formation of the SEI film will consume a large amount of active lithium, resulting in a decrease in the actual energy density of the battery compared to the theoretical calculated value. During the cyclic charge and discharge process of the battery, the cracking and crushing of the positive electrode active material particles, the thickening and repair of the SEI film will continuously consume active lithium, resulting in a continuous decline in the battery cycle performance. In order to further improve the energy density and cycle performance of the battery, adding a lithium supplement to the positive electrode plate can effectively alleviate the problems of low battery energy density, low first-cycle efficiency, and poor cycle life. However, the current lithium supplements have problems such as high decomposition voltage, large particle size, and poor conductivity, which make it impossible for the lithium supplement to fully release lithium ions under low voltage conditions. In addition, the transmission path of electrons and ions in the lithium supplement is long, and the kinetic performance is poor.

[0053] Based on this, a composite lithium supplement material is proposed in the present application. By forming a lithium supplement agent inside a porous carrier, during the composite process of the lithium supplement agent and the porous carrier, the porous structure of the porous carrier can limit the particle size of the lithium supplement agent to below the pore size of the porous carrier, thereby obtaining a lithium supplement agent with smaller particle size and higher uniformity, effectively increasing the reaction sites of the lithium supplement agent and shortening the transmission path of electrons and ions of the lithium supplement agent. In addition, since the nitrogen element doped in the porous carbon carrier will change the atomic and electronic arrangement in the porous carbon carrier and increase its conductivity, the overall conductivity of the porous carbon carrier is improved, which can jointly improve the kinetic performance of the lithium supplement agent; at the same time, since there is an in-situ grown transition metal compound on the inner surface of the porous carrier pore structure, the transition metal compound can act as a catalyst to catalyze the decomposition and lithium-release reaction of the lithium supplement agent, thereby reducing the decomposition voltage of the lithium supplement agent, so that the lithium supplement agent can fully release lithium ions under low voltage conditions.

[0054] The battery disclosed in the embodiments of the present application can be used in an electrical device that uses the battery as a power source, or a power supply system that uses the battery disclosed in the present application to form the electrical device, or various energy storage systems that use the battery as an energy storage element. Electrical devices may include mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0055] It should be understood that the technical solutions described in the embodiments of the present application are not limited to the batteries and electrical devices described above, but can also be applied to all other electrical devices including batteries and using batteries. However, for the sake of simplicity, the following embodiments are explained using electric vehicles as an example.

[0056] In the first aspect of the present application, referring to FIG1 , the present application proposes a composite lithium supplement material comprising: a porous carrier 100, wherein the porous carrier 100 is a nitrogen-doped porous carbon carrier, and a transition metal compound 110 is present on the inner surface of the pore structure of the porous carrier 100; and a lithium supplement agent 200, wherein the lithium supplement agent 200 is located within the pores of the porous carrier 100. By confining the lithium supplement agent within the pore structure of the nitrogen-doped porous carbon carrier, the particle size of the lithium supplement agent can be limited to below the micron level, thereby increasing the number of reaction sites per unit mass of the lithium supplement agent. Combined with the porous carbon carrier having excellent electrical conductivity, the kinetic performance of the lithium supplement agent can be improved. Furthermore, the transition metal compound in situ composited on the porous carrier can catalyze the decomposition of the lithium supplement agent, reduce the decomposition voltage of the lithium supplement agent, and facilitate the full decomposition of the lithium supplement agent. By adding the aforementioned composite lithium supplement material to a battery, the utilization efficiency of the lithium supplement agent can be effectively improved, alleviating problems such as low first-cycle efficiency and poor cycle life of the battery.

[0057] In some embodiments, a nitrogen-doped porous carbon support having a transition metal compound on its inner surface can be obtained by heat-treating a Prussian blue analogue. A lithium-replenishing agent can then be formed within the pore structure of the porous carbon support through a molding process. For example, the lithium-replenishing agent can be formed within the pore structure of the porous carbon support through recrystallization. For example, a Prussian blue analogue can be heat-treated to simultaneously form the nitrogen-doped porous carbon support and simultaneously grow the transition metal compound in situ on the inner surface of the porous carbon support, thereby obtaining a nitrogen-doped porous carbon support having a transition metal compound embedded in the inner surface of the pore structure in a one-step process. The lithium-replenishing agent can then be formed within the pore structure of the porous carbon support through recrystallization, thereby obtaining a composite lithium-replenishing material.

[0058] In some embodiments, the transition metal compound may include at least one of a transition metal carbide, a transition metal nitride, a transition metal phosphide, a transition metal oxide, a transition metal sulfide, and a transition metal selenide.

[0059] A porous structure refers to a network of interconnected or enclosed pores. Porous materials have a large specific surface area. The pores of a porous structure can accommodate substances of a specific particle size, which is greater than or equal to the minimum pore size and less than or equal to the maximum pore size. In other words, the particle size of the substance formed in the porous structure is limited by the pore size of the porous structure.

[0060] In some embodiments, the transition metal compound is contacted with a lithium replenishing agent.

[0061] An in-situ grown transition metal compound exists on the inner surface of the porous support's pore structure. When the transition metal compound comes into direct contact with the lithium supplement, it can better serve as a catalyst for the lithium supplement's decomposition and release reaction, further reducing the lithium supplement's decomposition voltage and allowing the lithium supplement to fully release lithium ions under low voltage conditions.

[0062] In some embodiments, the mass fraction of the transition metal in the porous support is 10% to 50%.

[0063] As an example, the mass fraction of the transition metal in the porous support can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48% or 50%.

[0064] The "mass fraction of transition metals" herein has a well-known meaning in the art and can be measured using instruments and methods known in the art. For example, the mass fraction of transition metals in the porous support can be measured using a Thermo ICAP7400 inductively coupled plasma-optical emission spectrometer (ICP-OES).

[0065] When the mass fraction of the transition metal in the porous support can be 10%-50%, the transition metal content in the porous support is moderate, which can provide more catalytic sites and have a higher carbon content, thereby having better conductivity.

[0066] In some embodiments, the particle size of the transition metal compound is 10 nm to 200 nm.

[0067] As an example, the particle size of the transition metal compound may be 10 nm, 20 nm, 50 nm, 70 nm, 90 nm, 100 nm, 110 nm, 120 nm, 150 nm, 170 nm, 190 nm, or 200 nm.

[0068] The term "particle size" as used herein has a well-known meaning in the art and can be measured using instruments and methods known in the art. For example, the particle size of the transition metal compound in the porous support can be measured using a FEI Talos-S high-angle annular dark-field scanning transmission electron microscope.

[0069] When the particle size of the transition metal compound is 10nm-200nm, the transition metal compound can fully contact with the lithium supplement agent, catalyze the decomposition and release of lithium by the lithium supplement agent, and reduce the decomposition voltage of the lithium supplement agent. At the same time, the transition metal compound will not occupy the pore structure of the porous carrier too much, which is conducive to the formation of the lithium supplement agent within the pore structure of the porous carrier.

[0070] In some embodiments, the transition metal compound satisfies the chemical formula M a X b , wherein M includes at least one of Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, and Ta, and X includes at least one of C, N, P, O, S, and Se; 0<a≤3, 0≤b≤4.

[0071] When the transition metal includes the aforementioned elements, the catalytic effect of the transition metal compound can be further enhanced.

[0072] In some embodiments, the porous support has a Dv50 particle size of 1 μm to 20 μm.

[0073] As an example, the Dv50 particle size of the porous support can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0074] The term "particle size" as used herein has a well-known meaning in the art and can be measured using instruments and methods known in the art. For example, the particle size of the porous support can be measured using laser diffraction particle size analysis. Specifically, the particle size of the porous support can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with standard GB / T 19077-2016.

[0075] When the Dv50 particle size of the porous carrier is 1μm-20μm, the particle size of the porous carrier is relatively moderate, the interior of the porous carrier can accommodate more lithium supplements, and the ion transmission path of the lithium supplement located in the central area of ​​the porous carrier is shorter and the kinetic performance is better.

[0076] In some embodiments, the porous support has a porosity of 20% to 60%.

[0077] As an example, the porosity of the porous support can be 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58% or 60%.

[0078] The term "porosity" as used herein has a well-known meaning in the art and can be measured using instruments and methods known in the art. As an example, the porosity of a porous support can be measured using the following method:

[0079] A sample of mass m is weighed and placed naturally in a measuring cup. The apparent volume V1 of the material is recorded. The sample is then placed in an AccuPyc II 1340 density tester. Helium or nitrogen is introduced according to the program and the test is started. After the test is completed, the actual volume V2 of the sample is obtained. The porosity of the sample can be calculated as (V1-V2) / V1×100%.

[0080] When the porosity of the porous carrier is 20%-60%, the interior of the porous carrier has more space for accommodating the lithium supplement agent, and the porous carrier has more through-hole structures, which is conducive to the formation of the lithium supplement agent in the pore structure and the release of lithium ions.

[0081] In some embodiments, the average pore size of the porous support is from 1 nm to 100 nm.

[0082] As an example, the average pore size of the porous support can be 1 nm, 5 nm, 8 nm, 10 nm, 11 nm, 15 nm, 18 nm, 20 nm, 21 nm, 25 nm, 28 nm, 30 nm, 31 nm, 35 nm, 38 nm, 40 nm, 41 nm, 45 nm, 48 nm, 50 nm, 51 nm, 55 nm, 58 nm, 60 nm, 61 nm, 65 nm, 68 nm, 70 nm, 71 nm, 75 nm, 78 nm, 80 nm, 81 nm, 85 nm, 88 nm, 90 nm, 91 nm, 95 nm, 98 nm or 100 nm.

[0083] The "average pore size" in this application has a well-known meaning in the art and can be measured using instruments and methods known in the art. As an example, the average pore size of a porous support can be measured using the following method:

[0084] Using the American Microscope multi-station fully automatic specific surface area and pore analyzer GeminiVII2390, about 7g of sample was taken and placed in a 9cc long tube with a bulb, degassed at 200℃ for 2h, and then placed in the main unit for testing to obtain the pore size data of the material.

[0085] When the average pore size of the porous carrier is 1nm-100nm, the particle size of the lithium supplement agent formed in the pores of the porous carrier is limited by the pore size of the porous carrier, thereby limiting the particle size of the lithium supplement agent to below the micron level. Furthermore, the particle size of the lithium supplement agent can be limited to below the nanometer level, achieving higher particle size uniformity.

[0086] In some embodiments, the composite lithium supplement material satisfies at least one of the following conditions: the nitrogen content of the composite lithium supplement material is 0.5%-5%; the carbon content of the composite lithium supplement material is 0.5%-5%; the carbon content of the composite lithium supplement material is 2%-30%.

[0087] The nitrogen content of the composite lithium-supplementing material refers to the mass fraction of the nitrogen element in the composite lithium-supplementing material; the carbon content of the composite lithium-supplementing material refers to the mass fraction of the carbon element in the composite lithium-supplementing material.

[0088] As an example, the nitrogen content of the composite lithium-supplementing material can be 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.5%, 3.8%, 4.0%, 4.2%, 4.5%, 4.8% or 5%.

[0089] As an example, the carbon content of the composite lithium supplement material can be 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.5%, 3.8%, 4.0%, 4.2%, 4.5%, 4.8% or 5%.

[0090] By mixing a Prussian blue analogue with a carbon source to obtain a mixture, and then heating the mixture, a porous carrier with a high carbon content can be obtained, thereby obtaining a composite lithium supplement material with a high carbon content.

[0091] As an example, the carbon content of the composite lithium supplement material can be 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8%, 8.5%, 9.0%, 9.5%, 10.0%, 10.5%, 11.0%, 11.5%, 12%, 12.5%, 13.0%, 13.5%, 14.0%, 14.5%, 15%, 15.5%, 16. .0%, 16.5%, 17.0%, 17.5%, 18.0%, 18.5%, 19%, 19.5%, 20.0%, 20.5%, 21.0%, 21.5%, 22%, 22.5%, 23.0%, 23.5%, 24.0%, 24.5%, 25%, 25.5%, 26.0%, 26.5%, 27.0%, 27.5%, 28.0%, 28.5%, 29%, 29.5% or 30.0%.

[0092] When the nitrogen content and / or carbon content of the composite lithium-replenishing material is within the aforementioned range, the nitrogen element doped in the porous carbon support will change the atomic and electron arrangement in the porous carbon support, increase its conductivity, thereby improving the overall conductivity of the porous carbon support, and thus the composite lithium-replenishing material has better conductivity.

[0093] In some embodiments, the Dv50 particle size of the composite lithium supplementing material is 1 μm-30 μm.

[0094] As an example, the Dv50 particle size of the composite lithium supplement material can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm or 30μm.

[0095] As used herein, "particle size" has a meaning generally known in the art and can be measured using instruments and methods generally known in the art. For example, the particle size of the composite lithium-supplementing material can be measured using laser diffraction particle size analysis. Specifically, the particle size of the composite lithium-supplementing material can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with standard GB / T 19077-2016.

[0096] In some embodiments, the Dv50 particle size of the composite lithium supplementing material is 1 μm-20 μm.

[0097] As an example, the Dv50 particle size of the composite lithium supplement material can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm or 20μm.

[0098] When the lithium supplement agent is formed in the pores of the porous carrier through recrystallization, the lithium supplement agent crystallizes and grows in the pores of the porous carrier, thereby making the particle size of the composite lithium supplement material close to that of the porous carrier.

[0099] In some embodiments, when the concentration of the lithium supplement solution is high during the recrystallization treatment, in addition to crystallizing and growing within the pore structure of the porous carrier, part of the lithium supplement will also crystallize and grow on the outer surface of the porous carrier, thereby making the particle size of the composite lithium supplement material slightly larger than the particle size of the porous carrier. However, the lithium supplement located on the outer surface of the porous carrier has a large particle size and cannot be catalytically decomposed by the transition metal compound, so it still has a high decomposition voltage and poor kinetic performance.

[0100] The aforementioned Dv50 particle size refers to the particle size corresponding to when the cumulative volume distribution percentage of the particles reaches 50%.

[0101] In some embodiments, the particle size of the lithium supplement agent is 5 nm to 100 nm.

[0102] As an example, the particle size of the lithium supplement agent can be 5nm, 8nm, 10nm, 11nm, 15nm, 18nm, 20nm, 21nm, 25nm, 28nm, 30nm, 31nm, 35nm, 38nm, 40nm, 41nm, 45nm, 48nm, 50nm, 51nm, 55nm, 58nm, 60nm, 61nm, 65nm, 68nm, 70nm, 71nm, 75nm, 78nm, 80nm, 81nm, 85nm, 88nm, 90nm, 91nm, 95nm, 98nm or 100nm.

[0103] When the particle size of the lithium supplement agent is 5nm-100nm, the particle size of the lithium supplement agent is smaller, the number of reaction sites per unit mass of the lithium supplement agent is more, the transmission path of electrons and ions is shorter, and it has better kinetic performance.

[0104] In some embodiments, the lithium supplement may include at least one of Li2C2O4, Li2C4O4, Li2C3O5, Li2C4O6, Li2C2O2N4, Li2O, Li2O2, Li2S, and LiF.

[0105] By adding the above lithium supplement agent to the positive electrode plate, the cycle life and first-cycle efficiency of the battery can be improved.

[0106] In some embodiments, the lithium supplement may include at least one of Li2C2O4, Li2C4O4, Li2C3O5, Li2C4O6, and Li2C2O2N4.

[0107] When the lithium supplement agent includes at least one of the aforementioned lithium supplement agents, the lithium supplement agent is more evenly distributed in the porous carbon carrier, the particle size uniformity of the lithium supplement agent is higher, and the lithium ion release performance is better.

[0108] In the second aspect of the present application, referring to FIG2 , the present application proposes a method for preparing a composite lithium supplement material, comprising:

[0109] S100: Provides Prussian blue analogs

[0110] In some embodiments, the Prussian blue analogue can be provided by the following method: adding M1 metal salt and sodium citrate to water to obtain a first solution; d (CN)6] was added to water to obtain a second solution; the first solution and the second solution were simultaneously added dropwise to the solvent and stirred to react to obtain the Prussian blue analogue M1 c [M2 d (CN)6] e .

[0111] As an example, 0.06 mol of M1 metal salt and 0.09 mol of sodium citrate can be added to 2 L of deionized water at room temperature to obtain a uniform first solution, and 0.04 mol of K3[M2 d (CN)6] was added to 2 L of deionized water to obtain a uniform second solution, and the first solution and the second solution were simultaneously added dropwise into a reactor containing deionized water (or other solvents) through a peristaltic pump and stirred for reaction to obtain a Prussian blue analogue.

[0112] In some embodiments, after the reaction of the first solution and the second solution in the reactor is completed, the precipitate of the Prussian blue analogue can be collected by centrifugation, the precipitate can be washed with deionized water and ethanol, and the washed product can be dried in an oven to obtain a dry Prussian blue analogue.

[0113] As an example, when the washed product is dried in an oven, the temperature of the oven can be 50°C-100°C, for example, the temperature of the oven can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C; the drying time can be 10h-15h, for example, the drying time can be 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h or 15h.

[0114] In some embodiments, the Prussian blue analog may satisfy the chemical formula; M1 c [M2 d (CN)6] e , wherein M1 and M2 independently include transition metal elements, 0<c≤4, 0<d≤4, 0<e≤3.

[0115] In some embodiments, M1 and M2 each independently include at least one of Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, and Ta.

[0116] Compared to metal-organic frameworks (MOFs), Prussian blue analogs are simple to prepare, relatively inexpensive, and easily scalable for industrial production. Prussian blue analogs possess an open three-dimensional framework structure and can include multiple transition metal elements, making them suitable as precursors for transition metal compounds and templates for porous supports. High-temperature treatment in a specific atmosphere can in situ generate nitrogen-doped porous carbon supports loaded with transition metal compounds.

[0117] When MOFs are heated to carbonize at high temperatures, the transition metals within them migrate to the outer surface of the material, where they aggregate. Simultaneously, the concentration of the transition metals within the material is too low, resulting in a highly uneven distribution of the transition metals. This aggregated transition metal provides too few catalytic sites, significantly reducing its catalytic activity. Furthermore, the low concentration of transition metals within the material also results in extremely low catalytic efficiency.

[0118] In this application, when a Prussian blue analogue is used to generate a transition metal compound in situ under high temperature conditions, the transition metal compound has a stronger bond to the porous support and is less likely to fall off. Furthermore, due to the highly ordered metal sites in the Prussian blue analogue, the metal can be evenly dispersed in the porous support after heat treatment, making it less likely to agglomerate, thereby enhancing the catalytic activity of the transition metal.

[0119] S200: Heat treatment of Prussian blue analogs

[0120] In some embodiments, in this step, the Prussian blue analog is heat-treated to obtain a porous support, and the obtained porous support is a nitrogen-doped porous carbon support, and a transition metal compound exists on the inner surface of the pore structure of the porous support.

[0121] In some embodiments, the heat treatment can meet at least one of the following conditions: the atmosphere of the heat treatment includes at least one of air, oxygen, nitrogen, argon, phosphine, hydrogen sulfide, sulfur vapor, and selenium vapor; the temperature of the heat treatment is 300°C-1000°C, so that a variety of transition metal compounds with better catalytic properties can be obtained.

[0122] As an example, the temperature of the heat treatment can be 300℃, 330℃, 360℃, 380℃, 400℃, 430℃, 460℃, 480℃, 500℃, 530℃, 560℃, 580℃, 600℃, 630℃, 660℃, 680℃, 700℃, 730℃, 760℃, 780℃, 800℃, 830℃, 860℃, 880℃, 900℃, 930℃, 960℃, 980℃ or 1000℃.

[0123] In some embodiments, when the heat treatment atmosphere includes at least one of air and oxygen and the heat treatment temperature is 300° C.-700° C., a transition metal oxide embedded on the inner surface of the porous support can be obtained by heat treating the Prussian blue analog.

[0124] In some embodiments, when the heat treatment atmosphere includes at least one of nitrogen and argon and the heat treatment temperature is 600°C-1000°C, a transition metal nitride embedded on the inner surface of the porous support can be obtained by heat treating the Prussian blue analog.

[0125] In some embodiments, when the heat treatment atmosphere includes phosphine and the heat treatment temperature is 300° C.-600° C., a transition metal phosphide embedded on the inner surface of the porous support can be obtained by heat treating the Prussian blue analog.

[0126] In some embodiments, when the atmosphere of the heat treatment includes at least one of sulfur vapor and selenium vapor, and the heat treatment temperature is 400°C-800°C, transition metal sulfides and / or transition metal selenides embedded on the inner surface of the porous support can be obtained by heat treating the Prussian blue analogue.

[0127] In some embodiments, the heating treatment time is 1 hour to 6 hours.

[0128] S300: Dissolve the porous carrier in the lithium supplement solution and dry it

[0129] In some embodiments, in this step, the porous carrier is dissolved in a lithium supplement solution and dried. Specifically, the drying process may include a recrystallization process, which evaporates the solvent in the lithium supplement solution, allowing the solute lithium supplement to crystallize and grow within the pore structure of the porous carrier, thereby obtaining a lithium supplement with smaller particle size, better conductivity, and lower decomposition voltage, thereby obtaining a composite lithium supplement material with better lithium supplement performance.

[0130] In some embodiments, the lithium supplement solution satisfies at least one of the following conditions: the mass concentration of the lithium supplement solution is 1%-10%; and the solvent of the lithium supplement solution includes water. The mass concentration of the lithium supplement solution refers to the mass concentration of the lithium supplement in the lithium supplement solution.

[0131] As an example, the mass solubility of the lithium supplement solution may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0132] When the mass concentration of the lithium supplement solution is 1%-10%, it can not only provide sufficient lithium source to allow the lithium supplement to fill the pore structure of the porous carrier as much as possible, but also reduce the growth of the lithium supplement on the outer surface of the porous carrier due to excessive lithium supplement, thereby producing a lithium supplement with a larger particle size, which is not conducive to reducing the decomposition voltage of the lithium supplement, nor is it conducive to improving the kinetic performance of the lithium supplement.

[0133] In some embodiments, the recrystallization process satisfies at least one of the following conditions: a temperature of 60°C to 100°C, a rotation speed of 500 rpm to 1000 rpm, and a stirring time of 1 to 5 hours. This can further improve the particle size uniformity and recrystallization yield of the lithium supplement.

[0134] In some embodiments, referring to FIG3 , the heating process may further include:

[0135] S110: Mixing a Prussian blue analog with a carbon source to obtain a mixture

[0136] In some embodiments, a carbon source is mixed with a Prussian blue analog in this step. The carbon source may include at least one of melamine, dicyandiamide, glucose, sodium citrate, vitamin C, polyvinyl alcohol, polypyrrole, and polyethylene glycol. This can increase the carbon content in the porous support, thereby improving the conductivity of the porous support.

[0137] As an example, the number average molecular weight of polyvinyl alcohol may be 50,000-200,000; the number average molecular weight of polypyrrole may be 10,000-150,000; and the number average molecular weight of polyethylene glycol may be 1,000-20,000.

[0138] In some embodiments, the mass of the Prussian blue analog in the mixture is m1, the mass of the carbon source in the mixture is m2, and the ratio of m1:m2 is 100:(10-40).

[0139] As an example, m1:m2 can be 100:10, 100:12, 100:15, 100:18, 100:20, 100:22, 100:25, 100:28, 100:30, 100:32, 100:35, 100:38 or 100:40.

[0140] When m1:m2 is 100:(10-40), the conductivity of the composite lithium-supplementing material can be improved without causing the specific capacity of the composite lithium-supplementing material to be too low.

[0141] S120: The mixture is subjected to a heating treatment.

[0142] In some embodiments, the conditions for heating the mixture can refer to the aforementioned conditions for heating the Prussian blue analog, which will not be described in detail here.

[0143] In some embodiments, the atmosphere for heating the mixture may include at least one of nitrogen, argon, phosphine, hydrogen sulfide, sulfur vapor, and selenium vapor; and the temperature for heating the mixture may be 300°C-1000°C.

[0144] Those skilled in the art will understand that the order in which the steps in the method for preparing a composite lithium supplement material are written does not imply a strict execution order and does not constitute any limitation on the implementation process. In the specific implementation of the above method, the specific execution order of each step should be determined by its function and possible internal logic.

[0145] It should be noted that the relevant parameters in the above-mentioned method for preparing the composite lithium supplement material, such as the type of specific substance, physical parameters, chemical parameters, etc., can refer to some or all of the technical features in the aforementioned embodiment. The parts not described in the embodiment of the preparation method can also refer to the aforementioned embodiment and related drawings, and will not be repeated here.

[0146] The above description of the various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced with each other and will not be repeated herein for the sake of brevity.

[0147] In a third aspect, the present application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises the aforementioned composite lithium-supplementing material and / or a composite lithium-supplementing material prepared using the aforementioned method. Thus, the positive electrode sheet possesses all the features and advantages of the aforementioned composite lithium-supplementing material and the method for preparing the composite lithium-supplementing material, and no further details are given here.

[0148] In some embodiments, the positive electrode active material layer further includes positive electrode active material, the mass of the composite lithium supplement material in the positive electrode active material layer is m3, the mass of the positive electrode active material in the positive electrode active material layer is m4, and m3:m4 is (0.5-20):100.

[0149] As an example, m3:m4 may be 0.5:100, 1:100, 3:100, 5:100, 7:100, 9:100, 11:100, 13:100, 15:100, 17:100, 19:100 or 20:100.

[0150] The composite lithium-supplementing material has a specific capacity several times that of the positive electrode active material. During the first cycle of charging of the battery, more lithium ions are released through the composite lithium-supplementing material to compensate for the initial lithium loss of the battery, thereby improving the battery's service life and cycle performance.

[0151] When m3:m4 is (0.5-20):100, the content of positive electrode active material in the positive electrode sheet is relatively high, thereby increasing the number of lithium-deintercalating sites on the positive electrode sheet, thereby increasing the energy density of the positive electrode sheet. At the same time, the content of the composite lithium-supplementing material is moderate, thereby releasing more lithium ions during the first charging of the battery, compensating for the lithium ion loss caused by the first effect of the battery, providing active lithium ions that can meet the long-term cycle of the battery, and effectively improving the cycle performance of the battery.

[0152] In some embodiments, m3:m4 is (1-10):100.

[0153] When m3:m4 is (1-10):100, the battery has both higher energy density and better cycle performance.

[0154] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0155] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and 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.).

[0156] In some embodiments, when the battery is a lithium ion battery, the positive electrode active material may be a positive electrode active material for lithium ion batteries known in the art.

[0157] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. The modified compounds of the above materials may be modified by doping and / or surface coating the materials.

[0158] The battery's charge and discharge processes involve the intercalation and deintercalation of lithium, leading to different molar Li contents at different discharge states. The molar Li contents listed in this application for the positive electrode active materials refer to the initial state of the material, i.e., the state before addition. When the positive electrode active material is used in a battery system, the molar Li content will change after charge and discharge cycles.

[0159] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0160] In some embodiments, the positive active material layer may further optionally include a binder.

[0161] As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0162] In some embodiments, the positive active material layer may further optionally include a conductive agent.

[0163] 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.

[0164] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the composite lithium supplement material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0165] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the positive electrode active material, conductive agent, binder and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after drying, cold pressing and other processes to form a positive electrode active material layer, and then spraying, secondary coating and other methods on the surface of the positive electrode active material layer to composite the composite lithium supplement material with the positive electrode active material layer.

[0166] In a fourth aspect of the present application, the present application provides a battery comprising the aforementioned positive electrode sheet. Thus, the battery has all the features and advantages of the aforementioned positive electrode sheet, which will not be described in detail here.

[0167] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, metal active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing the metal active ions to pass through.

[0168] In some embodiments, the metal active ions may be lithium ions, and the battery may be a lithium ion battery.

[0169] [Negative electrode]

[0170] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0171] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0172] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0173] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode 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, lithium titanate, etc. Silicon-based materials include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials include at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0174] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include at least one of 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).

[0175] In some embodiments, the negative electrode active material layer may further include a conductive agent, which includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0176] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0177] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0178] [Electrolytes]

[0179] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0180] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0181] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0182] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl 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, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0183] 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 properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0184] [Isolation film]

[0185] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0186] In some embodiments, the material of the separator includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0187] The battery of the present application includes a battery cell form, a battery module form and a battery pack form. The battery, battery module and battery pack of the present application are described below with reference to the accompanying drawings as appropriate.

[0188] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0189] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0190] In some embodiments, the battery outer packaging may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the battery outer packaging may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0191] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square, or any other shape. For example, FIG4 shows a square-structured battery cell 5 as an example.

[0192] In some embodiments, referring to Figure 5, the outer packaging may include a shell 51 and a top cover assembly 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell can be one or more, and those skilled in the art can select according to specific actual needs.

[0193] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0194] Figure 6 shows an example battery module 4. Referring to Figure 6 , within the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0195] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0196] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0197] Figures 7 and 8 illustrate an example battery pack 1. Referring to Figures 7 and 8 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0198] In a fifth aspect of the present application, the present application provides an electrical device comprising the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here.

[0199] Batteries, battery modules, and battery packs can be used as power sources or energy storage units for electrical devices. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0200] As an electrical device, a battery, battery module or battery pack can be selected according to its usage requirements.

[0201] Figure 9 shows an example of an electric device. This device can be a pure electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0202] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0203] The present invention will be described below by way of specific examples. It should be noted that the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, they are determined according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments not specified by manufacturer are all commercially available conventional products.

[0204] Example 1

[0205] 1. Preparation of porous carrier

[0206] At 25°C, 5g of a Prussian blue analog Fe4[Fe(CN)6]3 and 1.5g of a carbon source, glucose, were added to a small amount of ethanol solution. The mixture was ball-milled at 400rpm for 4 hours and then dried in a dry environment at 80°C. The mixture was then heated in an argon furnace at 800°C for 4 hours. The resulting product was then soaked in 0.5M HCl for 12 hours to remove inorganic impurities such as salts. After centrifugal drying, the nitrogen-doped porous carbon support was obtained, wherein iron carbide was present on the inner surface of the pore structure of the porous carbon support.

[0207] 2. Preparation of composite lithium supplement materials

[0208] The recrystallization treatment is carried out at 25°C. The recrystallization treatment includes: dissolving 1g of lithium oxalate (Li2C2O4) as a lithium supplement agent in 100g of deionized water as a solvent, that is, the mass concentration of the lithium supplement agent solution is 1%, and then adding 1g of a porous carrier with a Dv50 particle size of 1.5μm, ultrasonically dispersing for 1h to obtain a suspension, and then stirring the above suspension in an oil bath at 80°C (recrystallization treatment temperature) and a stirring speed of 600rpm (recrystallization treatment speed) to allow the lithium oxalate to recrystallize in the porous carrier for 3h. After the water is completely evaporated, a composite lithium supplement material is obtained.

[0209] 3. Preparation of batteries

[0210]

Preparation of positive electrode sheet

[0211] The above-obtained composite lithium supplement material, lithium iron phosphate, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 5:92:1:2, and are thoroughly stirred and mixed to obtain a positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode current collector, and then dried, cold pressed, and cut to form a positive electrode active material layer to obtain a positive electrode sheet.

[0212]

Preparation of negative electrode sheet

[0213] The negative electrode active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in the solvent deionized water in a weight ratio of 96.2:0.8:0.8:1.2, and mixed evenly to prepare a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and after drying, cold pressing, and slitting, a negative electrode active material layer is formed to obtain a negative electrode sheet.

[0214] Preparation of electrolyte

[0215] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3 / 7, and LiPF6 lithium salt with a mass concentration of 12.5% ​​was dissolved in the organic solvent and stirred to obtain an electrolyte.

[0216]

Isolation film

[0217] Polypropylene film is used as the isolation film.

[0218]

Battery preparation

[0219] The aforementioned positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrodes to provide insulation. The cells are then wound to form bare cells, with tabs welded to the cells. The cells are then placed in an aluminum shell and baked at 80°C to remove moisture. The electrolyte is then injected and sealed to produce an uncharged battery. The uncharged battery then undergoes a series of processes, including resting, hot and cold pressing, formation, shaping, and capacity testing, to produce a battery.

[0220] The differences between Example 2-24 and Example 1 are shown in Table 1-1 and Table 1-2.

[0221] In Comparative Example 1, lithium oxalate is used to replace the composite lithium supplement material in Example 1, and the Dv50 particle size of the oxalic acid is 500 nm; in Comparative Example 2, no composite lithium supplement material is added, and the weight ratio of lithium iron phosphate, conductive agent carbon black, and binder polyvinylidene fluoride in the positive electrode slurry is 92:1:2.

[0222] Table 1-1

[0223] Table 1-2

[0224] The particle size of the composite lithium supplement material in Examples 1-24 was tested. Specifically, the particle size of the composite lithium supplement material can be measured using a laser particle size analyzer (eg, Malvern Master Size 3000) with reference to the standard GB / T 19077-2016.

[0225] The following tests were performed on the batteries in Examples 1-24 and Comparative Examples 1-2. The test results are shown in Table 2.

[0226] 1. Battery capacity retention test

[0227] At 60°C, charge the formed battery at a constant current of 1 / 3C to 3.65V, then charge it at a constant voltage of 3.65V to 0.05C, let it sit for 5 minutes, and then discharge it at a constant current of 1 / 3C to the discharge cut-off voltage. The resulting capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery and record the discharge capacity C0 of the battery after the nth cycle. n , then the battery capacity retention rate P after each cycle n =C n / C0×100%. In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 100th cycle corresponds to n=100. The data measured after 100 cycles under the above test conditions, that is, P 100 .

[0228] 2. Decomposition voltage test

[0229] After the first week of charging, the voltage (V) and capacity (Q) data of the charging process were recorded, and a dQ / dV plot was made against V. The potential corresponding to the oxidation peak was recorded. The peak potential greater than 3.65V was the decomposition voltage of the composite lithium supplement material.

[0230] Table 2

[0231] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A composite lithium supplement material, wherein: include: A porous carrier, wherein the porous carrier is a nitrogen-doped porous carbon carrier, and a transition metal compound exists on the inner surface of the pore structure of the porous carrier; A lithium supplement is located in the pores of the porous carrier.

2. The composite lithium supplement material according to claim 1, wherein: The transition metal compound includes at least one of transition metal carbides, transition metal nitrides, transition metal phosphides, transition metal oxides, transition metal sulfides, and transition metal selenides.

3. The composite lithium supplement material according to claim 1 or 2, wherein: The transition metal compound is in contact with the lithium supplement agent.

4. The composite lithium supplement material according to any one of claims 1 to 3, wherein: The mass fraction of the transition metal in the porous carrier is 10%-50%.

5. The composite lithium supplement material according to any one of claims 1 to 4, wherein: The particle size of the transition metal compound is 10nm-200nm.

6. The composite lithium supplement material according to any one of claims 1 to 5, wherein: The transition metal compound satisfies the chemical formula M a X b , wherein the M includes at least one of Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, and Ta, and the X includes at least one of C, N, P, O, S, and Se; 0<a≤3, 0≤b≤4.

7. The composite lithium supplement material according to any one of claims 1 to 6, wherein: The porous carrier satisfies at least one of the following conditions: The Dv50 particle size of the porous carrier is 1 μm-20 μm; The porosity of the porous carrier is 20%-60%; The average pore size of the porous carrier is 1 nm-100 nm.

8. The composite lithium supplement material according to any one of claims 1 to 7, wherein: The composite lithium supplement material meets at least one of the following conditions: The nitrogen content of the composite lithium supplement material is 0.5%-5%; The carbon content of the composite lithium supplement material is 0.5%-5%; The carbon content of the composite lithium supplement material is 2%-30%.

9. The composite lithium supplement material according to any one of claims 1 to 8, wherein: The Dv50 particle size of the composite lithium supplement material is 1 μm-30 μm.

10. The composite lithium supplement material according to claim 9, wherein: The Dv50 particle size of the composite lithium supplement material is 1 μm-20 μm.

11. The composite lithium supplement material according to any one of claims 1 to 10, wherein: The particle size of the lithium supplement agent is 5nm-100nm.

12. The composite lithium supplement material according to any one of claims 1 to 11, wherein: The lithium supplement includes at least one of Li2C2O4, Li2C4O4, Li2C3O5, Li2C4O6, Li2C2O2N4, Li2O, Li2O2, Li2S, and LiF.

13. The composite lithium supplement material according to claim 12, wherein: The lithium supplement includes at least one of Li2C2O4, Li2C4O4, Li2C3O5, Li2C4O6, and Li2C2O2N4.

14. A method for preparing a composite lithium supplement material, wherein: include: A Prussian blue analog is provided, wherein the Prussian blue analog satisfies the chemical formula; M1 c [M2 d (CN)6] e , where M1 and M2 Each independently comprises a transition metal element, 0<c≤4, 0<d≤4, 0<e≤3; Heat-treating a Prussian blue analog to obtain a porous support, wherein the porous support is a nitrogen-doped porous carbon support, and a transition metal compound exists on the inner surface of the pore structure of the porous support; The porous carrier is dissolved in a lithium supplementing agent solution and dried to obtain the composite lithium supplementing material.

15. The method according to claim 14, wherein: The Prussian blue analogue provided comprises: Adding M1 metal salt and sodium citrate into water to obtain a first solution; K3[M2 d (CN)6] was added to water to obtain a second solution; The first solution and the second solution are simultaneously added dropwise to the solvent and stirred for reaction to obtain the Prussian blue analog M1. c [M2 d (CN)6] e .

16. The method according to claim 14 or 15, wherein: The M1 and M2 independently include at least one of Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, and Ta.

17. The method according to any one of claims 14 to 16, wherein: The drying process includes a recrystallization process.

18. The method according to claim 17, wherein: The recrystallization treatment satisfies at least one of the following conditions: The temperature of the recrystallization treatment is 60°C-100°C; The rotation speed of the recrystallization treatment is 500rpm-1000rpm; The stirring time of the recrystallization treatment is 1h-5h.

19. The method according to any one of claims 14 to 18, wherein: The heating treatment satisfies at least one of the following conditions: The atmosphere of the heating treatment comprises at least one of air, oxygen, nitrogen, argon, phosphine, hydrogen sulfide, sulfur vapor, and selenium vapor; The temperature of the heating treatment is 300°C-1000°C; The heating treatment time is 1h-6h.

20. The method according to any one of claims 14 to 19, wherein: The heating treatment satisfies at least one of the following conditions: The atmosphere of the heating treatment includes at least one of air and oxygen, and the temperature of the heating treatment is 300° C.-700° C.; The atmosphere of the heating treatment includes at least one of nitrogen and argon, and the temperature of the heating treatment is 600° C.-1000° C.; The atmosphere of the heating treatment includes phosphine, and the temperature of the heating treatment is 300° C.-600° C.; The atmosphere of the heating treatment includes at least one of sulfur vapor and selenium vapor, and the temperature of the heating treatment is 400°C-800°C.

21. The method according to any one of claims 14 to 20, wherein: The lithium supplement solution satisfies at least one of the following conditions: The mass concentration of the lithium supplement solution is 1%-10%; The solvent of the lithium supplement solution includes water.

22. The method according to any one of claims 14 to 21, wherein: The heat treatment further includes: mixing the Prussian blue analogue with a carbon source to obtain a mixture, and subjecting the mixture to the heat treatment.

23. The method according to claim 22, wherein: The carbon source comprises at least one of melamine, dicyandiamide, glucose, sodium citrate, vitamin C, polyvinyl alcohol, polypyrrole and polyethylene glycol.

24. The method according to claim 22 or 23, wherein: The mass of the Prussian blue analog in the mixture is m1, the mass of the carbon source in the mixture is m2, and m1:m2 is 100:(10-40).

25. A positive electrode sheet, wherein: The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer located at least on one side of the positive electrode current collector, and the positive electrode active material layer includes the composite lithium supplement material according to any one of claims 1 to 13, and / or the composite lithium supplement material prepared by the method according to any one of claims 14 to 24.

26. The positive electrode sheet according to claim 25, wherein: The positive electrode active material layer further includes positive electrode active materials, the mass of the composite lithium supplement material in the positive electrode active material layer is m3, the mass of the positive electrode active material in the positive electrode active material layer is m4, and m3:m4 is (0.5-20):

100.

27. The positive electrode sheet according to claim 26, wherein: m3:m4 is (1-10):

100.

28. A battery, wherein: Comprising the positive electrode sheet as described in any one of claims 25-27.

29. An electrical device, wherein: Comprising the battery of claim 28.

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