Lithium supplement agent and preparation method thereof, positive pole piece, battery and electric device

Abstract

The invention discloses a lithium supplement agent and a preparation method thereof, a positive pole piece, a battery and a power utilization device, the lithium supplement agent is of a porous structure, the lithium supplement agent comprises an inner core, a catalyst and a conductive agent, and the inner core comprises an organic lithium supplement agent; the catalyst comprises at least one of transition metal oxide, transition metal carbide, transition metal nitride, transition metal sulfide and transition metal phosphide. Therefore, the decomposition voltage of the lithium supplement agent can be effectively reduced, so that the lithium supplement agent gives full play to the lithium supplement capacity, and meanwhile, the influence on other components in the battery is also reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a lithium supplement and a preparation method thereof, 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. How to further improve the energy density and cycle life of lithium-ion batteries is a research hotspot in the battery field. Lithium loss during the battery charging and discharging process is the main reason for the attenuation of battery capacity and energy density. However, the gram capacity of the currently widely used positive electrode active materials is already at a high level. Further improvement in the gram 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. By pre-lithiation of the battery, the lithium source consumed by the battery during the charging and discharging process can be replenished, thereby improving the battery's energy density and cycle life. However, the current pre-lithiation treatment is still in its early stages of development 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. Summary of the Invention

[0004] In its first aspect, the present application proposes a lithium supplement agent having a porous structure, comprising a core, a catalyst, and a conductive agent. The core comprises an organic lithium supplement agent; the catalyst comprises at least one of a transition metal oxide, a transition metal carbide, a transition metal nitride, a transition metal sulfide, and a transition metal phosphide. This effectively reduces the decomposition voltage of the lithium supplement agent, allowing the lithium supplement agent to fully utilize its lithium supplement capacity while minimizing its impact on other components in the battery.

[0005] In some embodiments, the core satisfies the chemical formula Li2C x O y , where 1≤x≤4, 3≤y≤6. Therefore, the decomposition products of the core have little effect on the battery performance.

[0006] In some embodiments, the average pore size of the lithium supplement agent is 50 nm to 200 nm, and / or the porosity of the lithium supplement agent is 25% to 40%, thereby facilitating full utilization of the lithium supplement capacity of the lithium supplement agent.

[0007] In some embodiments, the catalyst and / or the conductive agent are located within the porous structure, thereby further improving the lithium replenishing capacity of the lithium replenishing agent.

[0008] In some embodiments, the core comprises at least one of Li2CO3, Li2C2O4, Li2C4O4, Li2C4O6, and Li2C3O5. Thus, the decomposition products of the lithium supplement agent after the lithium supplement agent has fulfilled its lithium supplement capacity have little impact on the battery.

[0009] In some embodiments, the lithium supplement agent has a Dv50 particle size of 1 μm to 20 μm. Thus, the lithium supplement agent has a relatively high lithium supplement capacity.

[0010] In some embodiments, the catalyst satisfies the chemical formula T a Q b , wherein T includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, and Cr, Q includes at least one of O, C, N, S, and P, 0<a≤3, and 0<b≤5. Thus, the activation energy of the decomposition reaction of the lithium supplement can be effectively reduced.

[0011] In some embodiments, the catalyst includes at least one of NiO, Ni3N2, NiS, Ni2P, Co2O3, Co3O4, CoN, CoS, CoP, MnO2, MnN, MnS, Mn3P2, Fe2O3, Fe3O4, Fe2S3, Fe3P, CuO, Cu3N, CuS, Cu3P2, TiO2, TiN, TiS3, TiP, Nb2O5, NbN, NbS2, NbP, Cr2O3, CrN, Cr2S3, and Cr3P2. Thus, the catalyst can effectively reduce the activation energy of the decomposition reaction of the lithium supplement.

[0012] In some embodiments, the average particle size of the catalyst is 300 nm to 1 μm, thereby providing the catalyst with more catalytically active sites.

[0013] In some embodiments, the mass fraction of the catalyst in the lithium supplement is 1 wt% to 20 wt%, thereby improving the catalytic effect of the catalyst on the core decomposition and lithium release reaction.

[0014] In some embodiments, the conductive agent includes at least one of carbon nanotubes, graphene, carbon nanofibers, and carbon black, thereby improving the conductivity of the lithium supplement and the ionic conductivity of the lithium supplement.

[0015] In some embodiments, the mass fraction of the conductive agent in the lithium supplement is 1 wt%-25 wt%, thereby further improving the ionic conductivity of the lithium supplement.

[0016] In a second aspect, this application proposes a method for preparing the aforementioned lithium supplement, comprising: mixing a core, a catalyst, a conductive agent, and a pore-forming agent in a solvent to obtain a slurry; spray-drying the slurry to obtain a composite material; and calcining the composite material to obtain the lithium supplement. Thus, the aforementioned lithium supplement can be prepared by a relatively simple method.

[0017] In some embodiments, the mass fraction of the pore former in the slurry is 1%-10%, thereby facilitating the formation of a porous structure.

[0018] In some embodiments, the mass concentration of the slurry is 20 g / L-100 g / L, thereby improving the granulation effect of the composite material.

[0019] In some embodiments, the pore-forming agent comprises at least one of polyvinyl butyral, methylcellulose, stearic acid, urea, polyethylene glycol, and starch. Thus, the decomposition products of the pore-forming agent have little effect on the lithium replenishing capacity of the lithium replenishing agent.

[0020] In some embodiments, the air inlet temperature of the spray drying process is 120° C.-150° C., and the air outlet temperature of the spray drying process is 80° C.-100° C. Thus, the granulation effect of the composite material can be improved.

[0021] In some embodiments, the calcination temperature is 200° C.-400° C., and the calcination time is 3 h-10 h. This can improve the pore-forming effect of the pore-forming agent.

[0022] In a third aspect, the present application provides a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, wherein the positive electrode active material layer comprises the aforementioned lithium supplement agent, or a lithium supplement agent prepared using the aforementioned method. Thus, the positive electrode plate possesses all the features and advantages of the aforementioned lithium supplement agent and method for preparing the lithium supplement agent, and no further details are given here.

[0023] 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.

[0024] 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

[0025] 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:

[0026] Figure 1 This is a flow chart of a method for preparing a lithium supplement according to one embodiment of the present application;

[0027] Figure 2 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0028] Figure 3 yes Figure 2 An exploded view of a battery cell according to an embodiment of the present application is shown;

[0029] Figure 4 is a schematic diagram of a battery module according to an embodiment of the present application;

[0030] Figure 5 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0031] Figure 6 yes Figure 5 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0032] Figure 7 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application;

[0033] Figure 8 This is a scanning electron microscope image of a lithium supplement according to an embodiment of the present application.

[0034] Description of reference numerals:

[0035] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell;

[0036] 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present application in detail. Examples of the embodiments are shown in the accompanying drawings, but unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid unnecessary lengthiness in the following description and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0038] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0039] The terms "include" and "have" in the description and claims of this application and any variations thereof are open expressions, that is, including the contents specified in this application but not excluding other contents.

[0040] 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%.

[0041] " range " disclosed in the present 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 range 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 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range 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.

[0042] 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.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0044] 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.

[0045] During the first charge of a battery, the electrolyte undergoes a reduction-decomposition reaction on the surface of the negative electrode, forming a solid electrolyte interface film (SEI film). The formation of the SEI film consumes 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 battery's cyclic charge and discharge process, the cracking and shattering of the positive electrode active material, the rupture and repair of the SEI film, all continuously consume active lithium, causing a continuous decline in the battery's cycle performance. Adding a lithium supplement to the positive electrode can effectively alleviate problems such as low first-cycle efficiency and poor cycle life. However, currently commonly used lithium-rich metal oxide supplements, such as Li2NiO2, Li5FeO5, and Li6CoO4, can effectively replenish the active lithium consumed in the battery. However, the residues left after the lithium ions are released by these supplements increase the internal impedance of the battery, accelerate the decomposition and oxidation of the electrolyte, and in turn deteriorate the battery performance. Organic lithium replenishers, such as lithium-containing carbon oxides, leave a residue of carbon oxide gas after releasing lithium ions. This residue can be expelled from the battery through a degassing process, leaving minimal residual byproducts inside the battery and improving the battery's energy density. Furthermore, these lithium replenishers are inherently stable and can exist stably in air. Therefore, using lithium-containing carbon oxides as lithium replenishers not only compensates for active lithium lost during battery charge and discharge cycles, improving the battery's energy density, but also leaves virtually no residual byproducts inside the battery, minimizing the impact on the battery's long-term performance.

[0046] Current organic lithium supplements suffer from high decomposition voltages and poor conductivity. For example, organic lithium supplements typically require a voltage of 4.7V or higher to decompose effectively. Furthermore, due to their low ionic conductivity, lithium ions cannot be rapidly released, and their lithium supplement capacity can only be slowly utilized at low currents. Ultimately, organic lithium supplements are unable to fully release lithium ions in a short period of time under low voltage conditions. Common positive electrode active materials have a maximum voltage limit of less than 4.7V. For example, the upper voltage limit for charging lithium iron phosphate is 3.7V, and the upper voltage limit for charging nickel-cobalt-manganese ternary materials is 4.2V. Raising the battery's charging voltage above 4.7V will cause the positive electrode active material to collapse. Furthermore, the electrolyte will also undergo irreversible damage such as decomposition, gas production, and oxidation under high voltage conditions, deteriorating the battery's cycling performance.

[0047] In the present application, a core, a conductive agent and a catalyst are compounded to form a lithium supplement agent. By introducing a catalyst into the lithium supplement agent, the activation energy of the decomposition reaction of the lithium supplement agent is reduced, thereby reducing the decomposition voltage of the lithium supplement agent. By introducing a conductive agent into the lithium supplement agent, the conductivity of the lithium supplement agent is increased, thereby improving the kinetic performance of the lithium supplement agent and facilitating the release of lithium ions. Furthermore, by introducing a porous structure into the lithium supplement agent, the electrolyte can infiltrate into the interior of the lithium supplement agent. Compared with a granular lithium supplement agent, the porous structure can greatly increase the contact area between the lithium supplement agent and the electrolyte, while shortening the path for lithium ion escape, which is more conducive to lithium ion escape. At the same time, when the electrolyte has a better infiltration effect on the lithium supplement agent, it helps to promote the excellent conductive properties of the conductive agent, further improve the ionic conductivity of the lithium supplement agent, accelerate the migration rate of lithium ions, and help enhance the catalytic effect of the catalyst on the decomposition reaction of the lithium supplement agent, thereby further reducing the decomposition voltage of the lithium supplement agent, helping the decomposition reaction of the lithium supplement agent to proceed in the forward direction, so that the lithium supplement agent can fully exert its lithium supplement capacity at a lower voltage, reducing the impact of high-voltage decomposition conditions on other components in the battery.

[0048] In the first aspect of the present application, the present application proposes a lithium supplement agent, which has a porous structure and includes a core, a catalyst and a conductive agent. The core satisfies the chemical formula Li2C x O y , wherein 1≤x≤4, 3≤y≤6; the catalyst includes at least one of transition metal oxides, transition metal carbides, transition metal nitrides, transition metal sulfides, and transition metal phosphides, and the conductive agent may include a carbon material.

[0049] The porous structure helps the electrolyte penetrate the internal structure of the lithium supplement, thereby improving the electrolyte's wetting effect on the lithium supplement and shortening the lithium ion escape path. The electrolyte's superior wetting effect on the lithium supplement can also enhance the catalytic effect of the catalyst located within the lithium supplement, as well as the conductive agent's enhanced conductivity. As a result, the lithium supplement can fully decompose and release lithium at a lower voltage and have a faster lithium ion release rate, allowing the lithium supplement to quickly and fully release its lithium supplement capacity under low voltage conditions. While achieving a high lithium release efficiency, it can also effectively reduce the impact of high voltage conditions on other components in the battery.

[0050] In some embodiments, the core satisfies the chemical formula Li2C x O y , where 1≤x≤4, 3≤y≤6. Therefore, the core not only compensates for the active lithium lost during the battery's charge-discharge cycle, improving the battery's energy density, but also leaves virtually no residual byproducts inside the battery, minimizing the impact on the battery's long-term performance.

[0051] As an example, x may be 1, 2, 3, or 4.

[0052] As an example, y can be 3, 4, 5, or 6.

[0053] As an example, a can be 1, 2 or 3.

[0054] As an example, b can be 1, 2, 3 or 4.

[0055] In some embodiments, the catalyst satisfies the chemical formula T a Q b , wherein T includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, and Cr, Q includes at least one of O, C, N, S, and P, 0<a≤3, 0<b≤5.

[0056] In some embodiments, the catalyst may include at least one of NiO, Ni3N2, NiS, Ni2P, Co2O3, Co3O4, CoN, CoS, CoP, MnO2, MnN, MnS, Mn3P2, Fe2O3, Fe3O4, Fe2S3, Fe3P, CuO, Cu3N, CuS, Cu3P2, TiO2, TiN, TiS3, TiP, Nb2O5, NbN, NbS2, NbP, Cr2O3, CrN, Cr2S3, and Cr3P2.

[0057] When the catalyst includes the aforementioned substances, the metal elements in the catalyst are primarily transition metals. Compared to precious metals, transition metals are less expensive, which helps reduce the production cost of the catalyst. The catalytic performance of transition metal catalysts is similar to that of precious metal catalysts, and the preparation process is relatively simple.

[0058] In some embodiments, the core includes at least one of Li2CO3, Li2C2O4, Li2C4O4, Li2C4O6, and Li2C3O5.

[0059] In some embodiments, the core includes at least one of Li2CO3, Li2C2O4, and Li2C4O4.

[0060] When the core is made of the aforementioned substances, the residual gas after the core decomposes and releases lithium ions can be discharged from the battery through a degassing process, resulting in fewer residual byproducts inside the battery and less impact on the battery's long-term performance. Furthermore, this type of lithium supplement has good stability and can exist stably in air, making it easy to store and transport.

[0061] In some embodiments, the average pore size of the lithium supplement agent is 50 nm-200 nm, and / or the porosity of the lithium supplement agent is 25%-40%.

[0062] As an example, the average pore size of the lithium supplement may be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm.

[0063] When the average pore size of the lithium supplement agent is within the aforementioned range, it is beneficial for the electrolyte to better infiltrate the lithium supplement agent and for the lithium ions in the lithium supplement agent to be quickly released.

[0064] As an example, the porosity of the lithium supplement is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.

[0065] During the electrochemical reaction process inside the battery, there are some adverse effects such as redox decomposition of the electrolyte, corrosion reaction between the electrolyte and the positive electrode plate, and generation of by-products. The occurrence of the aforementioned adverse effects is related to the contact area between the positive electrode plate and the electrolyte. When the porosity of the lithium supplement agent is within the aforementioned range, the lithium supplement agent has better structural stability, the contact area between the lithium supplement agent and the electrolyte is moderate, and the electrolyte can more fully infiltrate the lithium supplement agent. At the same time, the contact area between the positive electrode plate and the electrolyte is moderate, which is conducive to reducing the occurrence of side reactions.

[0066] The "porosity and average pore size of the lithium supplement agent" in this application have meanings well known in the art and can be measured using instruments and methods well known in the art, for example, by using a BET surface area analyzer (BET) test.

[0067] In some embodiments, the catalyst and conductive agent are located within the lithium supplement agent, thereby enhancing contact between the catalyst and conductive agent and the core. Furthermore, the catalyst and / or conductive agent can be located within the porous structure of the lithium supplement agent. In this case, the conductive agent and catalyst can contact the electrolyte, further improving the conductivity of the lithium supplement agent and further reducing the decomposition voltage, thereby further maximizing the lithium supplement capacity of the lithium supplement agent.

[0068] In some embodiments, the lithium supplement has a Dv50 particle size of 1 μm-20 μm.

[0069] As an example, the Dv50 particle size of the lithium supplement may 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.

[0070] When the particle size of the lithium supplement agent is within the aforementioned range, the particle size of the lithium supplement agent is smaller, the number of reaction sites per unit mass of the core of the lithium supplement agent is greater, the transmission path of electrons and ions is shorter, and the core has better kinetic properties.

[0071] The aforementioned Dv50 particle size refers to the particle size corresponding to when the cumulative volume distribution percentage of the particles reaches 50%.

[0072] The "particle size of the lithium supplement" in this application has a well-known meaning in the art and can be measured using instruments and methods well-known in the art. For example, it can be measured using a laser particle size analyzer (Malvern Master Size 2000) with reference to the standard GB / T 19077-2016 / ISO 13320:2009. The specific testing process is as follows: take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure an 8%-12% light shielding), add 20ml of ethanol, and ultrasonicate for 5 minutes (53KHz / 120W) to ensure that the sample is completely dispersed. Then, the sample is measured according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0073] In some embodiments, the average particle size of the catalyst is 300 nm-1 μm.

[0074] As an example, the average particle size of the catalyst may be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, or 1 μm.

[0075] When the average particle size of the catalyst is within the aforementioned range, the average particle size of the catalyst is smaller than the particle size of the inner core, and the catalyst is more easily in full contact with the surface of the inner core, thereby achieving a better catalytic effect.

[0076] The "average particle size of the catalyst" in this application has a meaning well known in the art and can be measured using instruments and methods well known in the art. Specifically, it can be obtained by testing the raw materials of the catalyst particles before preparing the lithium supplement. For example, it can be measured using a laser particle size analyzer (MalvernMaster Size 2000) with reference to the standard GB / T 19077-2016 / ISO 13320:2009. The specific testing process is: take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure an 8%-12% shading), add 20 ml of ethanol, and ultrasonicate for 5 minutes (53KHz / 120W) to ensure that the sample is completely dispersed, and then measure the sample according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0077] In some embodiments, the mass fraction of the catalyst in the lithium supplement is 1 wt%-20 wt%.

[0078] As an example, the mass fraction of the catalyst in the lithium supplement can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%.

[0079] When the mass fraction of the lithium supplement agent in the catalyst is within the aforementioned range, the proportion of the catalyst in the lithium supplement agent is appropriate, the catalyst has a good catalytic effect on the decomposition and lithium-extraction reaction, which helps to further reduce the decomposition voltage of the lithium supplement agent, and the mass proportion of the core in the lithium supplement agent is high, thereby increasing the lithium supplement capacity of the lithium supplement agent.

[0080] The "mass fraction of the catalyst in the lithium supplement" in this application has a well-known meaning in the art and can be measured using instruments and methods well-known in the art. For example, it can be obtained by ICP (inductively coupled plasma mass spectrometry) testing.

[0081] In some embodiments, the conductive agent includes at least one of carbon nanotubes, graphene, carbon nanofibers, and carbon black.

[0082] As examples, the carbon black may include Ketjen Black, Super P.

[0083] The addition of a conductive agent can improve the conductivity of the lithium supplement agent and reduce the occurrence of polarization of the lithium supplement agent, which is beneficial to the release of lithium ions. The conductive agent in the residue after the decomposition of the lithium supplement agent can continue to play the role of a conductive agent in the positive electrode sheet, which helps to reduce the impedance of the positive electrode sheet.

[0084] As an example, when the conductive agent is carbon nanotubes, the particle size of the conductive agent may be 1 nm-100 nm; when the conductive agent is graphene, the particle size of the conductive agent may be 10 μm-40 μm.

[0085] It should be noted that the particle size of the conductive agent refers to the diameter of graphene flakes, and the thickness of graphene is 2nm-3nm. When the conductive agent is graphene, the spatial state of the graphene in the lithium supplement is not planar. In this case, the particle size of the lithium supplement can be less than or equal to the maximum flake diameter of the graphene.

[0086] In some embodiments, the mass fraction of the conductive agent in the lithium supplement is 1 wt%-25 wt%.

[0087] As an example, the mass fraction of the conductive agent in the lithium supplement can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt% or 25wt%.

[0088] When the mass fraction of the conductive agent in the catalyst is within the aforementioned range, the proportion of the conductive agent in the lithium supplement agent is appropriate, which can effectively improve the conductivity and ionic conductivity of the lithium supplement agent, and the mass proportion of the core in the lithium supplement agent is relatively high, thereby improving the lithium supplement capacity of the lithium supplement agent.

[0089] The "mass fraction of the conductive agent in the lithium supplement" in this application has a well-known meaning in the art and can be measured using instruments and methods well-known in the art, or can be converted based on the amount of conductive agent added during the preparation of the lithium supplement.

[0090] In the second aspect of the present application, the present application proposes a method for preparing the aforementioned lithium supplement, which is simple in process and can be used for large-scale production. Specifically, referring to Figure 1 , the method for preparing a lithium supplement may include:

[0091] S100: Mix the core, catalyst, conductive agent and pore-forming agent in a solvent

[0092] In some embodiments, in this step, the core, the catalyst, the conductive agent, and the pore-forming agent are uniformly mixed in a solvent to obtain a slurry.

[0093] In some embodiments, the solvent may include water. At 25°C, the core can be completely dissolved in the solvent to form a core solution. However, the catalyst, conductive agent, and pore-forming agent have low solubility in the solvent and can remain in their original state. Therefore, during the subsequent spray drying process, when the solvent evaporates and the core material recrystallizes and precipitates, the catalyst, conductive agent, and pore-forming agent mixed in the core solution will be embedded in the core during the precipitation process of the core material as the solvent evaporates, ultimately forming a composite material.

[0094] In some embodiments, the mass fraction of the pore former in the slurry is 1%-10%.

[0095] When the proportion of the pore-forming agent in the slurry is within the aforementioned range, the pore-forming agent can form more pore structures after high-temperature decomposition, and can also reduce the collapse of the porous structure of the lithium supplement agent caused by excessive pore formation.

[0096] As an example, the mass fraction of the pore former in the slurry can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.

[0097] In some embodiments, the mass concentration of the slurry is 20 g / L-100 g / L.

[0098] As an example, the mass concentration of the slurry may be 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, or 100 g / L.

[0099] When the mass concentration of the slurry is within the aforementioned range, it is beneficial to the ejection of the slurry during the spray drying process, and it is less likely that the product will stick to the wall and be unable to be collected or deteriorate, thereby improving the effect of the granulation process.

[0100] In some embodiments, the pore-forming agent comprises at least one of polyvinyl butyral, methylcellulose, stearic acid, urea, polyethylene glycol, and starch. Thus, the decomposition products of the pore-forming agent have little effect on the lithium replenishing capacity of the lithium replenishing agent.

[0101] The pore-forming agent decomposes to produce gas through subsequent calcination, forming a porous structure. Different pore-forming agents produce different decomposition products. For example, methylcellulose decomposes primarily into methane at high temperatures, also forming a carbon skeleton and a small amount of residue. Stearic acid directly vaporizes at high temperatures. As a result, the majority of the pore-forming agent's decomposition products escape as gas, leaving only a minimal amount of carbon-containing material. This residue has minimal adverse effects on the performance of the lithium supplement.

[0102] S200: spray drying the slurry

[0103] In some embodiments, the slurry is dried by a spray drying process in this step to obtain a composite material.

[0104] Spray drying is a granulation process in which a slurry is sprayed and then dried under the action of heat. Specifically, spray drying involves three stages: slurry atomization, contact between the droplets and hot air, and gas-solid separation. Spray drying process conditions need to be adjusted based on the slurry's viscosity and solids content. For example, spray drying requires controlling the appropriate inlet and outlet air temperatures, as well as the spray velocity, to ensure better atomization of the slurry, improve contact and mixing efficiency between the droplets and the hot air, and ultimately increase the spray drying yield.

[0105] In some embodiments, the air inlet temperature of the spray drying process is 120°C-150°C, and the air outlet temperature of the spray drying process is 80°C-100°C.

[0106] When the inlet air temperature of the spray drying process is within the above range, the solvent residue after volatilization is moderate, and the composite material obtained after drying is not easy to melt or decompose due to absorbing heat from the solvent, resulting in the product sticking to the wall and being unable to collect the material or the product deteriorating. It is also not easy to concentrate and become sticky due to excessive solvent, and then the slurry will stick to the wall or the wall, resulting in product agglomeration and reduced yield.

[0107] When the outlet air temperature of the centrifugal spray dryer is within the above range, the composite material in a dry or semi-dry state is not likely to continue to absorb heat due to the lack of solvent protection, causing the composite material to melt or decompose, nor will it stick together into a mass or aggregate and adhere to the bottom of the drying chamber due to being still in a semi-dry state.

[0108] S300: calcining the composite material

[0109] In some embodiments, the composite material is calcined in this step so that the pore-forming agent located inside the composite material undergoes a decomposition reaction to generate gas, and the gas flows from the inside of the composite material to the outside, ultimately forming a large number of pore structures inside and on the surface of the composite material, thereby obtaining a lithium supplement with a porous structure.

[0110] In some embodiments, the calcination temperature is 200° C.-400° C., and the calcination time is 3 h-10 h.

[0111] As an example, the temperature of the calcination treatment may be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C or 400°C.

[0112] As an example, the calcination treatment time may be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0113] When the calcination treatment conditions are within the aforementioned range, it is helpful for the full decomposition of the pore-forming agent to obtain a lithium supplement agent with a suitable porous structure, and it is also helpful for the catalyst, carbon material, and core to maintain structural stability and reduce unnecessary decomposition.

[0114] In some embodiments, the calcination process may be performed in an atmosphere of nitrogen or an inert gas.

[0115] In some embodiments, when the catalyst is partially dissolved in the slurry, the partially dissolved catalyst can be converted back into the corresponding catalyst by changing the atmosphere during the calcination process.

[0116] It should be noted that the relevant parameters in the above-mentioned method for preparing a lithium supplement, 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.

[0117] 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.

[0118] In a third aspect, the present application provides a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, wherein the positive electrode active material layer comprises the aforementioned lithium supplement agent, or a lithium supplement agent prepared using the aforementioned method. Thus, the positive electrode plate possesses all the features and advantages of the aforementioned lithium supplement agent and method for preparing the lithium supplement agent, and no further details are given here.

[0119] In some embodiments, the mass fraction of the lithium supplement agent in the positive electrode active material layer is 1 wt % to 20 wt %.

[0120] As an example, the mass fraction of the lithium supplement agent in the positive electrode active material layer can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%.

[0121] The lithium replenisher has a specific capacity several times that of the positive electrode active material. During the first cycle of charging of the battery, it can release a large amount of lithium ions to make up for the loss of lithium ions in the battery. However, the lithium replenisher does not have the ability to insert lithium. When the mass fraction of the lithium replenisher in the positive electrode active material layer is within the aforementioned range, the content of the positive electrode active material in the positive electrode plate is relatively high, thereby increasing the number of lithium-removable insertable sites on the positive electrode plate, thereby increasing the energy density of the positive electrode plate. At the same time, the content of the lithium replenisher is moderate, thereby releasing more lithium ions during the first charge of the battery, compensating for the lithium ion loss caused by the battery's initial efficiency and subsequent SEI film repair and thickening, providing active lithium ions that can meet the battery's long-term cycle requirements, and effectively improving the battery's cycle performance.

[0122] 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.

[0123] 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.).

[0124] 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.

[0125] 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 0.05 O2) 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.

[0126] 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.

[0127] 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.

[0128] In some embodiments, the positive active material layer may further optionally include a binder.

[0129] 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.

[0130] In some embodiments, the positive active material layer may further optionally include a conductive agent.

[0131] 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.

[0132] 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, lithium supplement, conductive agent, 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.

[0133] 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, 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 lithium supplement agent with the positive electrode active material layer.

[0134] In a fourth aspect of the present application, a battery is provided, 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.

[0135] 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.

[0136] In some embodiments, the metal active ions may be lithium ions, and the battery may be a lithium ion battery.

[0137] [Negative electrode]

[0138] 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.

[0139] 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.

[0140] 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.).

[0141] 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.

[0142] 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).

[0143] 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.

[0144] 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)).

[0145] 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.

[0146] [Electrolytes]

[0147] 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.

[0148] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] [Isolation film]

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0158] 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.

[0159] The present application has no particular restrictions on the shape of the battery, which can be cylindrical, square or any other shape. For example, Figure 2 The battery cell 5 is a square structure as an example.

[0160] In some embodiments, reference Figure 3 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 form 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.

[0161] 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.

[0162] Figure 4 4 is an example of a battery module. Figure 4 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0163] 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.

[0164] 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.

[0165] Figure 5 and Figure 6 The battery pack 1 is used as an example. Figure 5 and Figure 6The battery pack 1 may include a battery box and multiple battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0166] 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.

[0167] 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.

[0168] As an electrical device, a battery, battery module or battery pack can be selected according to its usage requirements.

[0169] Figure 7 This is an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, a 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.

[0170] 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.

[0171] 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.

[0172] Example 1

[0173] Preparation of lithium supplements:

[0174] The core Li2C2O4, the catalyst NiO, the conductive agent carbon nanotubes, and the pore-forming agent stearic acid are mixed in water at a mass ratio of 75:15:10:5 and stirred evenly to obtain a slurry with a mass concentration of 50 g / L.

[0175] The slurry was spray-dried at an air inlet temperature of 120° C. and an air outlet temperature of 90° C. to obtain a composite material.

[0176] The composite material was calcined in a nitrogen atmosphere at a temperature of 300° C. for 5 hours to obtain a lithium supplement.

[0177] The mass concentration of the slurry in other embodiments and comparative examples is 50 g / L. The differences between other embodiments, comparative examples and Example 1 are shown in Table 1. Among them, no lithium supplement agent is added to the positive electrode sheet in Comparative Example 5, and lithium iron phosphate, conductive agent carbon black, and binder polyvinylidene fluoride are mixed in a mass ratio of 97:1.5:1.5 to obtain the positive electrode slurry.

[0178] Table 1

[0179]

[0180]

[0181] The lithium supplement agents in the above examples and comparative examples were tested as follows. The test results are shown in Table 2:

[0182] Average pore size and porosity test: Refer to GB / T 21650 and use BET test. The specific test process is as follows: (1) Pretreatment: Place an appropriate amount of sample in a dedicated sample tube, heat and vacuum degas for 2 hours, and weigh the total weight after cooling to room temperature. Subtract the mass of the sample tube to obtain the sample mass. (2) Test: Place the sample tube in the workstation and measure the amount of gas adsorbed on the solid surface at different adsorption pressures at a constant low temperature. Based on the adsorption-desorption isotherm obtained from the test, the pore size and porosity of the sample are equivalently calculated in combination with the BJH theoretical model (Barret-Joyner-Halenda).

[0183] Table 2

[0184]

[0185]

[0186] See also Figure 8 , Figure 8 is a scanning electron microscope image of the lithium supplement in Example 1, Figure 8 It can be seen that the lithium supplement agent in Example 1 is prepared by adding a pore-forming agent, and the pore-forming agent is decomposed to generate gas through calcination, thereby forming a lithium supplement agent with a porous structure.

[0187] The lithium supplement agents in the above examples and comparative examples are assembled into batteries in the following manner:

[0188]

Preparation of positive electrode sheet

[0189] The lithium supplement agent, lithium iron phosphate, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) obtained above are mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 4.5:92.5:1.5:1.5, and are thoroughly stirred and mixed to obtain a positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode collector, and then dried, cold pressed, and cut to form a positive electrode active material layer to obtain a positive electrode sheet.

[0190]

Preparation of negative electrode sheet

[0191] 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 97.2:0.8:0.8:1.2, and mixed evenly to prepare a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode 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.

[0192] Preparation of electrolyte

[0193] 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.

[0194]

Isolation film

[0195] Polypropylene film is used as the isolation film.

[0196]

Battery preparation

[0197] 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.

[0198] The batteries in the above examples and comparative examples were tested as follows. The test results are shown in Table 3:

[0199] Lithium replenisher decomposition voltage test: The above-mentioned battery was used as a test example and charged at a constant current rate of 0.1C with a charge cut-off voltage of 4.5V. The charge capacity (Q)-voltage (V) curve of the first cycle was recorded, and the dQ / dV-V curve was obtained by differentiating it. At the same time, the battery of the control example (see Comparative Example 5, no capacity lithium replenisher was added to the positive electrode plate, that is, lithium iron phosphate, conductive agent carbon black, and binder polyvinylidene fluoride were mixed in a mass ratio of 97:1.5:1.5 in the preparation of the positive electrode plate, and the rest was the same as the preparation method of the above-mentioned battery) was obtained under the same conditions. The dQ / dV-V curves of the test example and the control example were compared. An additional peak can be seen from the dQ / dV-V curve. This peak is the characteristic peak of the lithium replenisher, and the ordinate corresponding to the peak is the decomposition voltage of the lithium replenisher.

[0200] Initial Charge Capacity of the Lithium Supplement Agent: The batteries in the test example and control example described in the lithium supplement agent decomposition voltage test (see Comparative Example 5, where no capacity lithium supplement agent was added to the positive electrode sheet; i.e., lithium iron phosphate, conductive agent carbon black, and binder polyvinylidene fluoride were mixed in a mass ratio of 97:1.5:1.5 in the preparation of the positive electrode sheet, with all other preparation methods being the same as those described above) were each subjected to constant current charging at a rate of 0.1C, with a charge cutoff voltage of 4.5V, and the initial charge capacity was recorded. The initial charge capacity of the battery in the test example is denoted as A, and the initial charge capacity of the battery in the control example is denoted as B. The initial charge capacity of the lithium supplement agent is C = (A - 95.36% × B) / 4.64% (mAh / g). The contribution of the lithium supplement agent capacity to the initial charge capacity of the battery is 4.5 / 97 = 4.64%, and the contribution of the lithium iron phosphate capacity to the initial charge capacity of the battery is 92.5 / 97 = 95.36%.

[0201] Cycling performance test: The battery was discharged at 1C to 2.5V, then allowed to rest for 5 minutes. The charge and discharge cycle was then repeated: charging at 1C to 3.65V, then resting for another 5 minutes, and discharging at 1C to 2.5V. The discharge capacity (C0) during this process was recorded. Following the aforementioned charge and discharge cycle flow for 1000 cycles, the discharge capacity at the 1000th cycle was C1. The cycle capacity retention rate after 1000 cycles = C1 / C0 × 100%.

[0202] Table 3

[0203]

[0204] As shown in Table 3, the test results indicate that the porous structure of the lithium supplements in Examples 1-15 facilitates electrolyte penetration into the internal structure of the supplement, thereby improving the electrolyte's wetting of the supplement and shortening the lithium ion escape path. This superior electrolyte wetting of the supplement also enhances the catalytic effect of the catalyst within the supplement, as well as the conductive agent's enhanced conductivity. The supplement can fully decompose lithium at low voltages and exhibit a rapid lithium ion release rate, allowing the supplement to quickly and fully release its lithium capacity under low voltage conditions, resulting in high lithium release efficiency.

[0205] The lithium supplement agent in Comparative Example 1 does not have a porous structure, so the electrolyte has a poor infiltration effect on the internal structure of the lithium supplement agent, the decomposition voltage of the lithium supplement agent is relatively high, and the capacity that the lithium supplement agent can release during the first charging of the battery is low.

[0206] No catalyst was added to the lithium supplement in Comparative Example 2, which resulted in a significant increase in the decomposition voltage of the lithium supplement. The capacity released by the lithium supplement during the first charge of the battery was low, resulting in poor battery cycle performance.

[0207] In Comparative Example 3, no conductive agent was added to the lithium supplement agent, which significantly increased the decomposition voltage of the lithium supplement agent. The capacity released by the lithium supplement agent during the first charge of the battery was low, and the battery cycle performance was poor.

[0208] The lithium supplement agent in Comparative Example 4 only includes a core, and the decomposition voltage of the lithium supplement agent is too high. The lithium supplement agent has extremely poor ability to release lithium ions during the first charge of the battery. Compared with the battery in Comparative Example 5 in which no lithium supplement agent is added, the lithium supplement agent in Comparative Example 4 not only fails to improve the cycle performance of the battery, but also deteriorates the battery performance because the lithium supplement agent itself cannot fully decompose. After the lithium supplement agent is added to the positive electrode plate in Comparative Example 4, the cycle performance of the battery is further reduced.

[0209] 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 lithium supplement, characterized in that: The lithium supplement agent has a porous structure and includes a core, a catalyst and a conductive agent. The core includes an organic lithium supplement agent; the catalyst includes at least one of transition metal oxides, transition metal carbides, transition metal nitrides, transition metal sulfides, and transition metal phosphides.

2. The lithium supplement according to claim 1, characterized in that The core satisfies the chemical formula Li2C x O y , where 1≤x≤4, 3≤y≤6.

3. The lithium supplement according to claim 1 or 2, characterized in that The average pore size of the lithium supplement agent is 50 nm to 200 nm, and / or the porosity of the lithium supplement agent is 25% to 40%.

4. The lithium supplement according to any one of claims 1 to 3, characterized in that The catalyst and / or the conductive agent are located within the porous structure.

5. The lithium supplement according to any one of claims 1 to 4, characterized in that The core includes at least one of Li2CO3, Li2C2O4, Li2C4O4, Li2C4O6, and Li2C3O5.

6. The lithium supplement according to any one of claims 1 to 5, characterized in that: The Dv50 volume average particle size of the lithium supplement is 1 μm-20 μm.

7. The lithium supplement according to any one of claims 1 to 6, characterized in that The catalyst satisfies the chemical formula T a Q b , wherein T includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, and Cr, Q includes at least one of O, C, N, S, and P, 0<a≤3, 0<b≤5.

8. The lithium supplement according to claim 7, characterized in that The catalyst includes at least one of NiO, Ni3N2, NiS, Ni2P, Co2O3, Co3O4, CoN, CoS, CoP, MnO2, MnN, MnS, Mn3P2, Fe2O3, Fe3O4, Fe2S3, Fe3P, CuO, Cu3N, CuS, Cu3P2, TiO2, TiN, TiS3, TiP, Nb2O5, NbN, NbS2, NbP, Cr2O3, CrN, Cr2S3, and Cr3P2.

9. The lithium supplement according to any one of claims 1 to 8, characterized in that The average particle size of the catalyst is 300nm-1μm.

10. The lithium supplement according to any one of claims 1 to 9, characterized in that: The mass fraction of the catalyst in the lithium supplement agent is 1 wt%-20 wt%.

11. The lithium supplement according to any one of claims 1 to 10, characterized in that: The conductive agent includes at least one of carbon nanotubes, graphene, carbon nanofibers, and carbon black.

12. The lithium supplement according to any one of claims 1 to 11, characterized in that: The mass fraction of the conductive agent in the lithium supplement is 1 wt%-25 wt%.

13. A method for preparing the lithium supplement according to any one of claims 1 to 12, characterized in that: include: mixing the core, the catalyst, the conductive agent, and the pore-forming agent in a solvent to obtain a slurry; spray drying the slurry to obtain a composite material; The composite material is calcined to obtain the lithium supplement agent.

14. The method according to claim 13, characterized in that The mass fraction of the pore-forming agent in the slurry is 1%-10%.

15. The method according to claim 13 or 14, characterized in that The mass concentration of the slurry is 20g / L-100g / L.

16. The method according to any one of claims 13 to 15, characterized in that The pore-forming agent includes at least one of polyvinyl butyral, methyl cellulose, stearic acid, urea, polyethylene glycol, and starch.

17. The method according to any one of claims 13 to 16, characterized in that: The air inlet temperature of the spray drying process is 120°C-150°C, and the air outlet temperature of the spray drying process is 80°C-100°C.

18. The method according to any one of claims 13 to 17, characterized in that: The calcination temperature is 200° C.-400° C., and the calcination time is 3 h-10 h.

19. A positive electrode plate, characterized in that: The invention comprises a positive electrode current collector and a positive electrode active material layer at least located on one side of the positive electrode current collector, wherein the positive electrode active material layer comprises the lithium supplement agent according to any one of claims 1 to 12, or the lithium supplement agent prepared by the method according to any one of claims 13 to 18.

20. A battery, characterized in that: Including the positive electrode sheet according to claim 19.

21. An electrical device, characterized in that: Comprising the battery of claim 20.

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