Capacity compensation additive, preparation method thereof, positive pole piece, battery and electric device

Abstract

The invention discloses a capacity compensation additive and a preparation method thereof, a positive pole piece, a battery and an electric device, the capacity compensation additive comprises a capacity compensation agent and a catalyst-containing carbon material, and the catalyst-containing carbon material coats at least part of the surface of the capacity compensation agent. The capacity compensation additive disclosed by the invention has relatively low decomposition voltage, so that the capacity compensation additive can release active ions at relatively low voltage, and the released active ions can compensate the loss of the active ions in an SEI membrane forming process, so that the capacity of the battery is improved; and side reaction of electrolyte under high voltage and irreversible change and side reaction of a positive electrode active material structure are avoided, so that the cycle performance of the battery is improved.

Description

Technical Field

[0001] This application belongs to the field of batteries, and particularly relates to a capacity compensation additive, a preparation method thereof, a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] In recent years, with the increasingly wide application range of batteries, batteries are widely used in energy storage power systems such as hydraulic, thermal, wind, and solar power stations, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. During the formation process of the battery, the formation of the SEI film (solid electrolyte interface) on the surface of the negative electrode consumes a large amount of active ions, resulting in a low charge-discharge efficiency of the first cycle of the battery and serious irreversible capacity loss.

[0003] To solve the problems of low charge-discharge efficiency of the first cycle of the battery and serious irreversible capacity loss, capacity compensation of the positive electrode sheet is an effective solution idea. However, the existing capacity compensators have poor conductivity and require a relatively high decomposition voltage to achieve the extraction of active ions. At high voltages, side reactions are likely to occur in the electrolyte, and the structure of the positive active material will undergo irreversible changes, affecting the battery capacity and cycle performance. Summary of the Invention

[0004] In view of the technical problems in the background art, this application provides a capacity compensation additive, aiming to improve the capacity and cycle performance of the battery containing it.

[0005] To achieve the above object, a first aspect of this application proposes a capacity compensation additive, which includes a capacity compensator and a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator.

[0006] This application has at least the following beneficial effects: The catalyst-containing carbon material is used in the capacity compensation additive of this application, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator, that is, it is not easy for the catalyst to fall off from the capacity compensator, which is beneficial to the exertion of the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes in the structure of the positive active material at high voltages, thereby improving the battery cycle performance.

[0007] In some embodiments, the catalyst-containing carbon material includes a carbon carrier and a catalyst, the catalyst is loaded on at least part of the carbon carrier, and the catalyst includes M x Q y, where 1 ≤ x ≤ 6, 1 ≤ y ≤ 3, M includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, Mg or Cr. Optionally, M includes at least one of Ni, Co or Fe. Q includes at least one of O, N, S or P. Optionally, Q includes O and / or N. Thus, the capacity and cycle performance of the battery containing it can be improved.

[0008] In some embodiments, based on the total mass of the catalyst-containing carbon material, the mass ratio of the catalyst is 5% - 20%, optionally 5% - 15%. Thus, the capacity and cycle performance of the battery containing it can be improved.

[0009] In some embodiments, the particle size of the catalyst is 300 nm - 1 μm, optionally 500 nm - 800 nm. Thus, the catalytic effect on the decomposition of the capacity compensator can be improved.

[0010] In some embodiments, based on the total mass of the capacity compensation additive, the mass ratio of the catalyst-containing carbon material is 1% - 20%, optionally 5% - 10%. Thus, the cycle performance of the battery containing it can be improved.

[0011] In some embodiments, the capacity compensator includes A a C b O c , where A includes Na and / or Li, 2 ≤ a ≤ 4, 1 ≤ b ≤ 6, 3 ≤ c ≤ 6. Thus, it is beneficial to improve the energy density of the battery without deteriorating the power performance of the battery.

[0012] In some embodiments, the capacity compensator includes a lithium supplementing agent, and the lithium supplementing agent includes Li 2 CO 3 , Li 2 C 2 O 4 , Li 2 C 4 O 4 , Li 2 C 4 O 6 or Li 2 C 3 O 5 or at least one of Li 2 CO 3 , Li 2 C 2 O 4 or Li 2 C 4 O 4 Thus, it is beneficial to improve the energy density of the battery without deteriorating the power performance of the battery.

[0013] In some embodiments, the capacity compensator includes a sodium supplement, and the sodium supplement includes Na 2 CO 3 、Na 2 C 2 O 4 、Na 2 C 4 O 4 、Na 2 C 6 O 6 or Na 4 C 6 O 6 and at least one of them. Optionally, the sodium supplement includes Na 2 C 2 O 4 or Na 2 C 4 O 4 and at least one of them. Thereby, it is beneficial to improve the energy density of the battery without deteriorating the power performance of the battery.

[0014] In some embodiments, the volume average particle size Dv50 of the capacity compensation additive is 1 μm - 20 μm, and can be optionally 1 μm - 10 μm. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0015] In some embodiments, at 20 MPa, the powder resistivity of the capacity compensation additive is less than or equal to 5 Ω·cm, and can be optionally less than or equal to 1 Ω·cm. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0016] In some embodiments, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.5 V, and can be optionally lower than or equal to 4.3 V. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0017] In the second aspect of the present application, the present application proposes a method for preparing a capacity compensation additive, including: coating a carbon material containing a catalyst on at least a part of the surface of a capacity compensator to obtain a capacity compensation additive.

[0018] Therefore, the capacity compensation additive prepared in this application includes a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator. That is, it is not easy for the catalyst to fall off from the capacity compensator, which is conducive to the exertion of the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive electrode active material at high voltages, thereby improving the cycle performance of the battery.

[0019] In some embodiments, the coating of the catalyst-containing carbon material on at least part of the surface of the capacity compensator is carried out in the following manner: spray-drying a slurry comprising a catalyst-containing carbon material and a capacity compensator, so that the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0020] In some embodiments, the spray-drying includes at least one of the following conditions: the concentration of the slurry comprising a capacity compensator and a catalyst-containing carbon material is 20 g / L - 50 g / L, optionally 20 g / L - 30 g / L; the inlet air temperature is 120 °C - 150 °C; the outlet air temperature is 80 °C - 100 °C. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0021] In some embodiments, the coating of the catalyst-containing carbon material on at least part of the surface of the capacity compensator is carried out in the following manner: electrospinning a slurry comprising a catalyst-containing carbon material and a capacity compensator, so that the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0022] In some embodiments, the electrospinning includes at least one of the following conditions: the concentration of the slurry comprising a capacity compensator and a catalyst-containing carbon material is 5 g / L - 20 g / L; the pushing speed of the spinneret is 0.3 mL / h - 1 mL / h; the voltage between the spinneret and the receiver is 15 kV - 18 kV; the distance between the spinneret and the receiver is 12 cm - 20 cm. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0023] In the third aspect of this application, a positive electrode plate is proposed, which includes the capacity compensation additive described in the first aspect or the capacity compensation additive obtained by the method described in the second aspect. Thereby, the capacity and cycle performance of the battery containing it can be improved.

[0024] In some embodiments, the positive electrode tab includes a positive electrode active material layer, and the positive electrode active material layer includes the capacity compensation additive. Thereby, the capacity and cycle performance of the battery containing the same can be improved.

[0025] In some embodiments, based on the total mass of the positive electrode active material layer, the mass ratio of the capacity compensation additive is 1% - 20%, and optionally 1% - 5%. Thereby, the capacity and cycle performance of the battery containing the same can be improved.

[0026] In the fourth aspect of the present application, a battery is provided, which includes the positive electrode tab described in the third aspect. Thereby, the battery has a high capacity and cycle performance.

[0027] In the fifth aspect of the present application, an electrical device is provided, which includes the battery described in the fourth aspect. Thereby, the electrical device has an excellent service life.

[0028] The additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0030] Figure 1 is a schematic diagram of a battery according to an embodiment of the present application.

[0031] Figure 2 is Figure 1 an exploded view of the battery according to an embodiment of the present application shown in.

[0032] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0033] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0034] Figure 5 is Figure 4 an exploded view of the battery pack according to an embodiment of the present application shown in.

[0035] Figure 6 is a schematic diagram of an electrical device using the battery according to an embodiment of the present application as a power source.

[0036] Figure 7It is a comparison chart of the cycling curves of Example 1, Comparative Example 1, and Comparative Example 6.

[0037] Figure 8 It is an SEM image of the capacity compensation additive obtained in Example 1.

[0038] Figure 9 It is a distribution map of the Ni element in the EDS energy spectrum of the capacity compensation additive obtained in Example 1.

[0039] Description of the reference numerals:

[0040] 1 Battery cell; 11 Housing; 12 Electrode assembly; 13 Cover plate; 2 Battery module; 3 Battery pack; 31 Upper box; 32 Lower box. Detailed implementation manners

[0041] The embodiments of the technical solutions of the present application will be described in detail below. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0042] Referring to "embodiment" herein means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0043] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way may or may not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a particular parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0045] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0046] Unless otherwise specified, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0047] Currently, from the perspective of the development of the market situation, the application of secondary batteries is becoming more and more extensive. Secondary batteries are not only applied to energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles and electric cars, as well as multiple fields such as military equipment and aerospace. With the continuous expansion of the application fields of secondary batteries, the market demand is also continuously increasing.

[0048] During the formation process of secondary batteries, the formation of the SEI film (solid electrolyte interface) on the negative electrode surface will consume a large amount of active ions, resulting in a decrease in the charge-discharge efficiency of the first cycle of the battery and serious irreversible capacity loss.

[0049] In order to solve the problems of low charge-discharge efficiency of the first cycle of the battery and serious irreversible capacity loss, compensating the capacity of the positive electrode plate is an effective solution idea. Lithium supplementation for the negative electrode plate usually uses lithium flakes for lithium supplementation. Lithium flakes are very active in the electrolyte itself and are prone to reacting with the electrolyte, resulting in low lithium supplementation efficiency. And when lithium dendrites are generated on the negative electrode surface, the SEI film will continuously break and reconstruct, continuously consuming lithium, thereby reducing the cycle life of the battery. For the positive electrode plate, a lithium-rich additive or a lithiated active material is usually added as a lithium supplementing agent. The decomposition potential of this type of lithium supplementing agent is relatively high and it needs to decompose at a high voltage. However, at high voltages, the structure of the positive electrode active material will be damaged, and at the same time, the electrolyte will be oxidized and decomposed under high voltage, resulting in more side reactions, thereby reducing the cycle performance of the battery and being unfavorable for the exertion of the battery capacity.

[0050] The capacity compensation additive of the present application has a low decomposition voltage, enabling the capacity compensator to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive electrode active material at high voltages, thereby improving the battery cycle performance.

[0051] The capacity compensation additive disclosed in the embodiments of the present application is applicable to lithium-ion batteries and sodium-ion batteries, and the batteries disclosed in the embodiments of the present application can be used in electrical devices using the battery as a power source or various energy storage systems using the battery as an energy storage element. The electrical devices may include, but are not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys may include stationary or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc., and the spacecraft may include airplanes, rockets, space shuttles, and spaceships, etc.

[0052] The first aspect of the present application provides a capacity compensation additive, which includes a capacity compensator and a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator.

[0053] In the capacity compensation additive of the present application, a catalyst-containing carbon material is used, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator, that is, the catalyst and the capacity compensator are not easily separated, which is conducive to the exertion of the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes in the structure of the positive electrode active material at high voltages, thereby improving the battery cycle performance. In addition, when the capacity compensator in the capacity compensation additive is consumed, the catalyst-containing carbon material can still play a supporting role and will not cause changes in the structure of the electrode sheet.

[0054] In some embodiments of the present application, the catalyst-containing carbon material includes a carbon carrier and a catalyst, the catalyst is loaded on at least part of the carbon carrier, and the catalyst includes M x Q y, where 1 ≤ x ≤ 6 and 1 ≤ y ≤ 3, M may include at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, Mg, or Cr, and Q may include at least one of O, N, S, or P. Thus, by loading the metal compound on the carbon material, not only can the agglomeration of the catalyst be reduced, facilitating the exertion of the catalytic performance of the catalyst, but also the electrical conductivity of the catalyst can be significantly improved, thereby reducing the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive active material at high voltages, thereby improving the battery cycle performance. In some other embodiments of the present application, the M x Q y in M may include at least one of Ni, Co, or Fe, and Q may include O and / or N.

[0055] As an example, the M x Q y may include at least one of NiO, Ni 3 N 2 , NiS, Ni 2 P, CoO, CoN, CoS, CoP, MnO 2 , MnN, MnS, Mn 3 P 2 , Fe 2 O 3 , Fe 6 N 2 , Fe 2 S 3 , Fe 3 P, CuO, Cu 3 N, CuS, Cu 3 P 2 , TiO 2 , TiN, TiS 3 , TiP, Nb 2 O 5 , NbN, NbS 2 , NbP, MgO, Mg 3 N 2 , MgS, Mg 3 P 2 , Cr 2 O 3 , CrN, Cr 2 S 3 or Cr 3 P 2 and at least one of the above. In some other embodiments, the M x Q y may include NiO, Ni3 N 2 , CoO, CoN, MnO 2 , MnN, Fe 2 O 3 or Fe 6 N 2 at least one of them.

[0056] As an example, the carbon carrier may include but is not limited to carbon nanotubes, graphene, carbon nanofibers, etc.

[0057] In some embodiments of the present application, based on the total mass of the catalyst-containing carbon material, the mass ratio of the catalyst is 5%-20%, such as 7%-18%, 10%-15%, 10%-12%, etc. Thus, by using the catalyst-containing carbon material with the above composition, the catalytic property and conductivity of the catalyst-containing carbon material can be improved, thereby reducing the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte at high voltages and irreversible changes and side reactions in the structure of the positive electrode active material, thereby improving the battery cycle performance. In some other embodiments of the present application, based on the total mass of the catalyst-containing carbon material, the mass ratio of the catalyst is 5%-15%.

[0058] In some embodiments of the present application, the particle size of the catalyst can be 300 nm - 1 μm, such as 350 nm - 950 nm, 400 nm - 900 nm, 450 nm - 850 nm, 500 nm - 800 nm, 550 nm - 750 nm, 600 nm - 700 nm, 650 nm - 700 nm, etc. Thus, by using the catalyst with this particle size in the present application, it is not only evenly distributed on the carbon carrier, but also has an excellent catalytic effect on the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte at high voltages and irreversible changes and side reactions in the structure of the positive electrode active material, thereby improving the battery cycle performance. In some other embodiments of the present application, the particle size of the catalyst can be 500 nm - 800 nm.

[0059] In some embodiments of the present application, based on the total mass of the capacity compensation additive, the mass ratio of the catalyst-containing carbon material is 1% - 20%, such as 1% - 18%, 3% - 15%, 5% - 12%, 7% - 10%, etc. Thus, by adding the catalyst-containing carbon material with the above content to the capacity compensation additive, the decomposition voltage of the capacity compensation additive can be reduced, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive electrode active material at high voltages, thereby improving the battery cycle performance. In some other embodiments of the present application, based on the total mass of the capacity compensation additive, the mass ratio of the catalyst-containing carbon material is 5% - 10%.

[0060] In some embodiments of the present application, the capacity compensator includes A a C b O c , where A includes Na and / or Li, 2 ≤ a ≤ 4, 1 ≤ b ≤ 6, 3 ≤ c ≤ 6. Thus, with the capacity compensator having this composition, it decomposes to release active ions and carbon oxide gas. The released active ions can compensate for the loss of active ions during the formation of the SEI film, and the carbon oxide gas can be discharged in the exhaust process. Therefore, there are no residues after the decomposition of this capacity compensator, which is beneficial to improving the energy density of the battery and will not increase the impedance of the battery cell, thus not deteriorating the power performance of the battery.

[0061] In some embodiments of the present application, the capacity compensator includes a lithium supplement agent, and the lithium supplement agent includes Li 2 CO 3 、Li 2 C 2 O 4 、Li 2 C 4 O 4 、Li 2 C 4 O 6 or Li 2 C 3 O 5 or at least one of them. Thus, with the lithium supplement agent having this composition, it decomposes to release lithium ions and carbon oxide gas. The released lithium ions can compensate for the loss of lithium ions during the formation of the SEI film, and the carbon oxide gas can be discharged in the exhaust process. Therefore, there are no residues after the decomposition of this capacity compensator, which is beneficial to improving the energy density of the battery and will not increase the impedance of the battery cell, thus not deteriorating the power performance of the battery. In another embodiment of the present application, the lithium supplement agent includes Li 2 CO 3 、Li2 C 2 O 4 or Li 2 C 4 O 4 at least one of them.

[0062] In some embodiments of the present application, the capacity compensator includes a sodium supplementing agent, and the sodium supplementing agent includes Na 2 CO 3 , Na 2 C 2 O 4 , Na 2 C 4 O 4 , Na 2 C 6 O 6 or Na 4 C 6 O 6 at least one of them. Thus, with the sodium supplementing agent having such a composition, sodium ions and carbon oxide gas are released upon decomposition. The released sodium ions can compensate for the loss of sodium ions during the formation of the SEI film, and the carbon oxide gas can be discharged during the exhaust process. Therefore, there is no residue after the decomposition of this capacity compensator, which is beneficial to improving the energy density of the battery and will not increase the impedance of the battery cell, thus not deteriorating the power performance of the battery. In some other embodiments of the present application, the sodium supplementing agent includes Na 2 C 2 O 4 or Na 2 C 4 O 4 at least one of them.

[0063] In the present application, when the battery is a lithium-ion battery, the capacity compensator uses a lithium supplementing agent; when the battery is a sodium-ion battery, the capacity compensator uses a sodium supplementing agent.

[0064] In some embodiments of the present application, the volume average particle size Dv50 of the capacity compensation additive is 1 μm - 20 μm, such as 2 μm - 18 μm, 5 μm - 15 μm, 7 μm - 12 μm, 8 μm - 10 μm, etc. Thus, for the capacity compensation additive with such a particle size, the diffusion path of the active ions is appropriate and it is easy to escape. Therefore, the specific capacity of the capacity compensation additive can be improved, and the risk of agglomeration between particles can be reduced, thereby improving the capacity and cycle performance of the battery. In some other embodiments of the present application, the volume average particle size Dv50 of the capacity compensation additive is 1 μm - 10 μm.

[0065] In this application, Dv50 refers to the particle size corresponding to a cumulative volume distribution percentage of 50%. For example, referring to the standard GB / T 19077-2016 / ISO 13320:2009, it is measured using a laser particle size analyzer (Malvern Master Size 2000). The specific test process is as follows: Take an appropriate amount of the sample to be tested (the sample concentration should ensure a light obscuration of 8%-12%), add 20 ml of deionized water, and at the same time, ultrasonicate for 5 min (53 KHz / 120 W) to ensure complete dispersion of the sample. Then, measure the sample according to the standard GB / T19077-2016 / ISO 13320:2009.

[0066] In some embodiments of this application, at 20 MPa, the powder resistivity of the capacity compensation additive is less than or equal to 5 Ω·cm, such as 0.1 Ω·cm - 5 Ω·cm, 0.3 Ω·cm - 5 Ω·cm, 0.5 Ω·cm - 5 Ω·cm, 0.8 Ω·cm - 5 Ω·cm, 1 Ω·cm - 5 Ω·cm, 1.5 Ω·cm - 4.5 Ω·cm, 2 Ω·cm - 4 Ω·cm, 2.5 Ω·cm - 3.5 Ω·cm, 3 Ω·cm - 3.5 Ω·cm, etc. Thus, the capacity compensation additive of this application has high conductivity, which can reduce the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive active material at high voltages, thereby improving the battery cycle performance. In some other embodiments of this application, at 20 MPa, the powder resistivity of the capacity compensation additive is less than or equal to 1 Ω·cm. Thus, the capacity and cycle performance of the battery containing it can be improved.

[0067] In this application, the test method for powder resistivity can adopt the four-probe method or the two-probe method. The four-probe method includes: measuring the current and voltage on the powder sample using four probes, and calculating the resistivity based on the current and voltage. The two-probe method: measuring the current and voltage on the powder sample using two probes, and calculating the resistivity based on the current and voltage.

[0068] In some embodiments of the present application, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.5V, such as 3V - 4.5V, 3.2V - 4.2V, 3.5V - 4V, 3.5V - 3.8V, etc. Thus, the capacity compensation additive has a lower decomposition voltage, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes in the structure of the positive electrode active material at high voltages, thereby improving the battery cycle performance. In some other embodiments of the present application, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.3V.

[0069] In the present application, the meaning of the decomposition voltage of the capacity compensation additive refers to the starting voltage at which decomposition occurs during voltammetry testing or charge-discharge cycling. And the voltammetry testing method for "the decomposition voltage of the capacity compensation additive" in the present application includes cyclic voltammetry or linear sweep voltammetry.

[0070] The second aspect of the present application provides a method for preparing a capacity compensation additive, including: coating a carbon material containing a catalyst on at least a part of the surface of the capacity compensator to obtain the capacity compensation additive.

[0071] Thus, the capacity compensation additive prepared in the present application includes a carbon material containing a catalyst, and the carbon material containing a catalyst is coated on at least a part of the surface of the capacity compensator. That is, it is not easy for the catalyst to fall off from the capacity compensator, which is beneficial to the exertion of the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive. This enables the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive electrode active material at high voltages, thereby improving the battery cycle performance. Additionally, when the capacity compensator in the capacity compensation additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the structure of the electrode sheet.

[0072] In some embodiments of the present application, the carbon material containing a catalyst is coated on at least a part of the surface of the capacity compensator in the following manner: a slurry including the carbon material containing a catalyst and the capacity compensator is spray-dried, so that the carbon material containing a catalyst is coated on at least a part of the surface of the capacity compensator. Thus, by adopting the spray-drying process, the carbon material containing a catalyst can be tightly coated on the surface of the capacity compensator, is not easy to fall off, is beneficial to the exertion of the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive electrode active material at high voltages, thereby improving the cycle performance of the battery. In addition, when the capacity compensator in the capacity compensation additive is consumed, the carbon material containing a catalyst therein can still play a supporting role and will not cause changes in the structure of the electrode sheet.

[0073] As an example, the carbon material containing a catalyst, the capacity compensator and a solvent are mixed and stirred evenly to obtain a slurry, and the slurry is spray-dried so that the carbon material containing a catalyst is coated on at least a part of the surface of the capacity compensator to obtain a capacity compensation additive.

[0074] As an example, the solvent may include but is not limited to at least one of ethanol, deionized water, ethylene glycol, etc.

[0075] In some embodiments of the present application, the concentration of the slurry including the capacity compensator and the carbon material containing a catalyst in the spray-drying is 20 g / L - 50 g / L, such as 25 g / L - 45 g / L, 30 g / L - 40 g / L, 35 g / L - 40 g / L, etc. In some embodiments of the present application, the concentration of the slurry including the capacity compensator and the carbon material containing a catalyst is 20 g / L - 30 g / L.

[0076] In some embodiments of the present application, the inlet air temperature in the spray-drying is 120°C - 150°C, such as 125°C - 145°C, 130°C - 140°C, 135°C - 140°C, etc.; the outlet air temperature is 80°C - 100°C, such as 85°C - 95°C, 85°C - 90°C, etc.

[0077] In some other embodiments of the present application, the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensator in the following manner: electrospinning a slurry comprising the carbon material containing the catalyst and the capacity compensator, so that the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensator. Thus, by using the electrospinning process, the carbon material containing the catalyst can be tightly coated on the surface of the capacity compensator, is not easily detached, is beneficial to the exertion of the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, enabling the capacity compensation additive to release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte and irreversible changes and side reactions in the structure of the positive active material at high voltages, thereby improving the cycle performance of the battery. In addition, when the capacity compensator in the capacity compensation additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the structure of the electrode sheet.

[0078] As an example, the carbon material containing the catalyst, the capacity compensator and a solvent are mixed and stirred evenly to obtain a slurry, and the slurry is electrospun so that the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensator to obtain a capacity compensation additive.

[0079] As an example, the solvent may include but is not limited to at least one of N, N-dimethylformamide (DMF), tetrahydrofuran, dichloromethane, dimethyl sulfoxide (DMSO), etc.

[0080] In some embodiments of the present application, the concentration of the slurry comprising the capacity compensator and the carbon material containing the catalyst during the electrospinning process is 5 g / L - 20 g / L, such as 7.5 g / L - 17.5 g / L, 10 g / L - 15 g / L, 10 g / L - 12.5 g / L, etc.

[0081] In some embodiments of the present application, the pushing speed of the spinneret is 0.3 mL / h - 1 mL / h, such as 0.5 mL / h - 0.8 mL / h, 0.6 mL / h - 0.7 mL / h, etc.; the voltage between the spinneret and the receiver is 15 kV - 18 kV, such as 15 kV - 17 kV, 15 kV - 16 kV, etc.; the distance between the spinneret and the receiver is 12 cm - 20 cm, such as 12 cm - 18 cm, 15 cm - 17 cm, etc.

[0082] In the third aspect of the present application, a positive electrode sheet is proposed. The positive electrode sheet includes the capacity compensation additive described in the first aspect or the capacity compensation additive obtained by the method described in the second aspect. Thus, by adding the capacity compensation additive to the positive electrode sheet, the capacity compensation additive has a relatively low decomposition voltage and can release active ions at a relatively low voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte at high voltages and irreversible changes in the structure of the positive electrode active material, thereby improving the cycle performance and power performance of the battery. In addition, when the capacity compensator in the capacity compensation additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the structure of the positive electrode sheet.

[0083] In some embodiments of the present application, the positive electrode sheet includes a positive electrode active material layer, and the positive electrode active material layer includes the capacity compensation additive. Thus, by adding the above-mentioned capacity compensation additive to the positive electrode active material layer, the capacity compensation additive has a relatively low decomposition voltage and can release active ions at a relatively low voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte at high voltages and irreversible changes in the structure of the positive electrode active material, thereby improving the cycle performance and power performance of the battery. In addition, when the capacity compensator in the capacity compensation additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the structure of the positive electrode sheet.

[0084] In some embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass ratio of the capacity compensation additive is 1%-20%, such as 3%-18%, 5%-15%, 7%-13%, 7%-10%, etc. Thus, by adding the capacity compensation additive in the above content to the positive electrode active material layer, the capacity compensation additive has a relatively low decomposition voltage and can release active ions at a relatively low voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, improve the capacity of the battery, and avoid side reactions of the electrolyte at high voltages and irreversible changes in the structure of the positive electrode active material, thereby improving the cycle performance and power performance of the battery. In some other embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass ratio of the capacity compensation additive is 1%-5%.

[0085] The positive electrode sheet includes a positive electrode current collector, and the positive electrode active material layer is provided on at least one side of the positive electrode current collector.

[0086] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector.

[0087] In some embodiments of the present application, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as 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.).

[0088] In some embodiments of the present application, the positive electrode active material layer may further include a positive electrode active material, and the positive electrode active material may be a positive electrode active material for a battery known in the art.

[0089] As an example, when the positive electrode plate is used in a lithium-ion battery, the positive electrode active material may be a positive electrode active material for a lithium-ion battery known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate 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 conventional materials that can be used as the positive electrode active material of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), 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 O 2 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (which may also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (which may also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2O 2 (which can also be abbreviated as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (which can also be abbreviated as NCM 811 )、lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O 2 ) or at least one of its modified compounds, etc. Examples of olivine-structured lithium-containing phosphates can include but are not limited to lithium iron phosphate (such as LiFePO 4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate or a composite material of lithium manganese iron phosphate and carbon.

[0090] As an example, when the positive electrode sheet is used in a sodium-ion battery, the positive electrode active material can adopt the positive electrode active material for sodium-ion batteries well-known in the art. As an example, the positive electrode active material can include but is not limited to at least one of layered transition metal oxides, polyanion compounds, and Prussian blue analogs.

[0091] As an example of the above-mentioned layered transition metal oxides, for example, the following can be listed:

[0092] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 includes at least one of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, or Ba, 0 < x ≤ 0.33, 0 < h ≤ 0.24, 0 ≤ k ≤ 0.32, 0 < l ≤ 0.68, 0 ≤ m < 0.1, h + k + l + m = 1, 0 ≤ y < 0.2;

[0093] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O 2 , where M 2 includes at least one of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, or Ba, 0 < z ≤ 0.1;

[0094] Naa Li b Ni c Mn d Fe e O 2 , where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0095] Examples of the above polyanion compounds include, for example:

[0096] A 1 f M 3 g (PO 4 ) i O j X 1 3-j , where A 1 includes at least one of H, Li, Na, K, or NH 4 in M 3 includes at least one of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, or Zn, and X 1 is at least one of F, Cl, or Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0097] Na n M 4 PO 4 X 2 , where M 4 includes at least one of Mn, Fe, Co, Ni, Cu, or Zn, and X 2 is at least one of F, Cl, or Br, 0 < n ≤ 2;

[0098] Na p M 5 q (SO 4 ) 3 , where M 5 includes at least one of Mn, Fe, Co, Ni, Cu, or Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0099] Na s Mn t Fe 3-t (PO 4 ) 2 (P 2 O 7 )), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0100] Examples of the above-mentioned Prussian blue analogs include, for example:

[0101] A u M 6 v [M 7 (CN) 6 w ·xH 2 O, where A includes at least one of H + 、NH 4 + 、an alkali metal cation or an alkaline earth metal cation, M 6 and M 7 each independently include at least one of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A includes H + 、Li + 、Na + 、K + 、NH 4 + 、Rb + 、Cs + 、Fr + 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ or Ra 2+ at least one of, M 6 and M 7 each independently include at least cations of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn or W.

[0102] During the charge and discharge process of the battery, the deintercalation and consumption of Li or Na will occur, and the molar content of Li or Na is different when the battery is discharged to different states. In the listing of the positive electrode materials in this application, the molar content of Li or Na is the initial state of the material, that is, the state before feeding. When the positive electrode material is applied to the battery system, after charge and discharge cycles, the molar content of Li or Na will change.

[0103] In the listing of the positive electrode materials in this application, the molar content of oxygen is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of oxygen will fluctuate.

[0104] ​In some embodiments of the present application, the positive electrode active material layer may further optionally include a binder. 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, or fluorinated acrylate resin.

[0105] In some embodiments of the present application, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0106] In some embodiments, the positive electrode plate can be prepared by the following method: dispersing the components for preparing the positive electrode plate, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0107] The third aspect of the present application provides a battery, and the battery includes the positive electrode plate described in the second aspect of the present application. Thus, the battery of the present application has a relatively high capacity and cycling performance.

[0108] In some embodiments of the present application, the battery further includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0109] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0110] In some embodiments of the present application, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper 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.).

[0111] In some embodiments of the present application, the negative electrode active material may adopt the negative electrode active material for the battery 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. The silicon-based material may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, or silicon alloys. The tin-based material may include at least one of elemental tin, tin oxide compounds, or 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 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0112] In some embodiments of the present application, the negative electrode active material layer may further optionally 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), or carboxymethyl chitosan (CMCS).

[0113] In some embodiments of the present application, the negative electrode active material layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0114] In some embodiments of the present application, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0115] In some embodiments of the present application, the negative electrode sheet can be prepared in the following manner: 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 collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0116] Typically, a battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0117] The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0118] In some embodiments of the present application, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0119] In some embodiments of the present application, when the battery is a lithium-ion battery, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, or lithium tetrafluorooxalate phosphate.

[0120] In some embodiments of the present application, when the battery is a sodium-ion battery, the electrolyte salt may include at least one of sodium hexafluorophosphate, sodium difluorooxalate borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, or sodium bis(trifluoromethanesulfonyl)imide.

[0121] In some embodiments of the present application, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethylene glycol dimethyl ether, methyl ethyl sulfone, or diethyl sulfone.

[0122] In some embodiments of the present application, the electrolytic solution may also optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain performance of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, etc.

[0123] The present application does not particularly limit the type of the separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0124] In some embodiments, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or 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.

[0125] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0126] In some embodiments, the secondary battery may include an outer package. The outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0127] In some embodiments, the outer packaging of the secondary battery can be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The outer packaging of the secondary battery can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0128] This application does not particularly limit the shape of the battery, which can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 is a battery cell 1 with a square structure as an example.

[0129] In some embodiments, referring to Figure 2 , the outer packaging can include a housing 11 and a cover plate 13. Among them, the housing 11 can include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly 12 through a winding process or a stacking process. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 12. The number of electrode assemblies 12 included in the battery cell 1 can be one or more, and those skilled in the art can select according to specific actual needs.

[0130] In some embodiments, the battery can be assembled into a battery module, and the number of batteries included in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.

[0131] Figure 3 is a battery module 2 as an example. Referring to Figure 3 , in the battery module 2, a plurality of battery cells 1 can be arranged in sequence along the length direction of the battery module 2. Of course, they can also be arranged in any other arbitrary manner. Further, the plurality of battery cells 1 can be fixed by fasteners.

[0132] Optionally, the battery module 2 can further include a housing with a receiving space, and a plurality of battery cells 1 are accommodated in the receiving space.

[0133] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.

[0134] Figure 4 and Figure 5 is a battery pack 3 as an example. Referring to Figure 6 and Figure 7, the battery pack 3 may include a battery box and a plurality of battery modules 2 disposed in the battery box. The battery box includes an upper box body 31 and a lower box body 32. The upper box body 31 can be covered on the lower box body 32 to form a closed space for accommodating the battery modules 2. The plurality of battery modules 2 can be arranged in the battery box in any manner.

[0135] In addition, the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0136] As the electrical device, the secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0137] Figure 6 is an electrical device as an example. The electrical device is a pure electric vehicle, hybrid electric vehicle, or plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the secondary battery, a battery pack or battery module can be used.

[0138] Another example of the device can be a mobile phone, tablet computer, laptop computer, etc. This device usually requires thin and light, and a battery can be used as the power source.

[0139] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, the technologies or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0140] Example 1

[0141] 1. Preparation of the positive electrode sheet

[0142] a. Preparation of the capacity compensation additive

[0143] Weigh 1 g of nickel oxide (particle size 500 nm - 800 m) as a catalyst and place it in a quartz boat. Then, put the quartz boat into the reaction furnace for chemical vapor deposition, introduce nitrogen, control the flow rate at 500 sccm, heat up to 800 °C, introduce acetylene as a carbon source, react for 1 h, cool down, and obtain carbon nanotubes containing the catalyst. After performing composition analysis using ICP (Inductively Coupled Plasma Mass Spectrometer), the mass content of nickel oxide in the carbon nanotubes containing the catalyst is measured to be 15 wt%;

[0144] Weigh lithium oxalate and the carbon nanotubes containing the catalyst in a mass ratio of 9:1, mix them in water at a concentration of 20 g / L, stir for 2 h, control the feeding rate of spray drying at 200 ml / h, the inlet air temperature at 120 °C, and the outlet air temperature at 90 °C to obtain a capacity compensation additive.

[0145] b. Preparation of the positive electrode plate

[0146] Mix the positive electrode active material lithium iron phosphate, acetylene black, polyvinylidene fluoride, and the above-mentioned capacity compensation additive in a mass ratio of 90.25:3:2:4.75 in an appropriate amount of solvent N-methylpyrrolidone (NMP) to obtain a positive electrode slurry. Coat the positive electrode slurry on both sides of the positive electrode current collector aluminum foil, and through drying and cold pressing, form a negative electrode active material layer on both sides of the positive electrode current collector, and then perform strip cutting and cutting operations to obtain the positive electrode plate.

[0147] 2. Preparation of the negative electrode plate

[0148] Mix the negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC-Na) in a mass ratio of 96:1:1.5:1.5 in an appropriate amount of solvent deionized water to obtain a negative electrode slurry. Coat the negative electrode slurry on both sides of the negative electrode current collector copper foil, and through drying and cold pressing, form a negative electrode active material layer on both sides of the negative electrode current collector, and finally perform strip cutting and cutting operations to obtain the negative electrode plate.

[0149] 3. Preparation of the electrolyte

[0150] In a glove box under an argon atmosphere (H 2 O < 0.1 ppm, O 2 < 0.1 ppm), mix ethylene carbonate and ethyl methyl carbonate in a mass ratio of 30:70 to obtain a solvent, dissolve the fully dried electrolyte salt LiPF 6 in the above solvent, and after mixing evenly, obtain an electrolyte with a concentration of 1 mol / L.

[0151] 4. Separator

[0152] Use a polypropylene membrane as the separator.

[0153] 5. Preparation of Secondary Battery

[0154] Stack the positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator placed between the positive and negative electrode sheets to play an isolation role, and then wind to obtain an electrode assembly; place the electrode assembly in an outer package, inject the prepared electrolyte into the dried lithium-ion battery, and after vacuum packaging, standing, formation, and shaping processes, a lithium-ion battery is obtained.

[0155] The preparation methods of the lithium-ion batteries of Examples 2-11, 14-22, and Comparative Examples 1-2 and 4 are the same as those of Example 1, except that the process of preparing the positive electrode sheet is different, as shown in Table 1 specifically.

[0156] The preparation method of the lithium-ion battery of Example 12 is the same as that of Example 1, except that the method of preparing the carbon material containing a catalyst is different, specifically including: adding 0.75 g of NiO and 4.25 g of graphene to 200 ml of deionized water and stirring for 1 h to mix evenly, then transferring the mixture to a reaction kettle and placing it in a homogeneous reactor, maintaining at 180 °C for 15 h and then performing centrifugation and drying to obtain a sample of nickel oxide loaded on graphene.

[0157] The preparation method of the lithium-ion battery of Example 13 is the same as that of Example 1, except that the method of preparing the carbon material containing a catalyst is different, specifically including: adding 0.75 g of NiO and 4.25 g of carbon nanofibers to 200 ml of deionized water and stirring for 1 h to mix evenly, then transferring the mixture to a reaction kettle and placing it in a homogeneous reactor, maintaining at 180 °C for 15 h and then performing centrifugation and drying to obtain a sample of nickel oxide loaded on carbon nanofibers.

[0158] The preparation method of the lithium-ion battery of Example 23 is the same as that of Example 1, except that the preparation method of the capacity compensation additive in the process of preparing the positive electrode sheet is different, specifically including: weighing 1 g of nickel oxide as a catalyst and placing it in a quartz boat, then putting the quartz boat into the reaction furnace for chemical vapor deposition, introducing nitrogen, controlling the flow rate at 500 sccm, heating to 800 °C, introducing acetylene as a carbon source, reacting for 1 h, cooling to obtain carbon nanotubes containing a catalyst, and through ICP component analysis, the content of nickel oxide in the carbon nanotubes containing a catalyst is measured to be 15 wt%; weighing lithium oxalate and carbon nanotubes containing a catalyst according to a mass ratio of 9:1, mixing in ethanol at a concentration of 10 g / L, stirring for 2 h to obtain a spinning solution, adjusting the pushing speed of the spinneret to 0.5 mL / h, the voltage between the spinneret and the receiver to 18 kV, and the distance between the spinneret and the receiver to 15 cm to spin into a capacity compensation additive.

[0159] Comparative Example 3

[0160] The preparation method of the lithium-ion battery is the same as that of Example 1, except that the process of preparing the capacity compensation additive in the positive electrode sheet is different, as specifically shown in Table 1.

[0161] The method for preparing the capacity compensation additive includes:

[0162] Weigh 1 g of nickel oxide as a catalyst and place it in a quartz boat. Then, put the quartz boat into the reaction furnace for chemical vapor deposition, introduce nitrogen, control the flow rate at 500 sccm, heat up to 800 °C, introduce acetylene as a carbon source, react for 1 h, cool down, and obtain carbon nanotubes containing the catalyst. After performing component analysis with ICP (Inductively Coupled Plasma Mass Spectrometer), the content of nickel oxide in the carbon nanotubes containing the catalyst is measured to be 15 wt%.

[0163] Weigh lithium oxalate and carbon nanotubes containing the catalyst according to a mass ratio of 9:1, mix them in water at a concentration of 100 g / L, then grind them with a sand mill for 2 h, control the rotation speed at 1000 revolutions per minute, and after drying, obtain the capacity compensation additive.

[0164] Comparative Example 5

[0165] The preparation method of the lithium-ion battery is the same as that of Example 1, except that the process of preparing the capacity compensation additive in the positive electrode sheet is different, as specifically shown in Table 1.

[0166] The method for preparing the capacity compensation additive includes:

[0167] Weigh 1 g of nickel oxide as a catalyst and place it in a quartz boat. Then, put the quartz boat into the reaction furnace for chemical vapor deposition, introduce nitrogen, control the flow rate at 500 sccm, heat up to 800 °C, introduce acetylene as a carbon source, react for 1 h, cool down, and obtain carbon nanotubes containing the catalyst. After performing component analysis with ICP (Inductively Coupled Plasma Mass Spectrometer), the content of nickel oxide in the carbon nanotubes containing the catalyst is measured to be 15 wt%.

[0168] Weigh lithium oxalate and carbon nanotubes containing the catalyst according to a mass ratio of 9:1, mix them in water at a concentration of 5 g / L, then drop this solution into ethanol, and the capacity compensation additive crystallizes out in ethanol. After suction filtration and drying, obtain the capacity compensation additive.

[0169] Comparative Example 6

[0170] The preparation method of the lithium-ion battery is the same as that of Example 1, except that no capacity compensation additive is added to the positive electrode sheet, as specifically shown in Table 1.

[0171]

[0172]

[0173] The powder resistivity and decomposition voltage of the capacity compensation additives obtained in Examples 1-23 and Comparative Examples 1-6 as well as the first charge capacity and cycle performance of the battery were characterized. The characterization results are shown in Table 2.

[0174] (1) Decomposition voltage test of capacity compensation additives

[0175] Preparation of button cells:

[0176] a. Preparation of positive electrode sheet:

[0177] Lithium iron phosphate, capacity compensation additive, acetylene black, and binder polyvinylidene fluoride were dissolved in a solvent N-methylpyrrolidone (NMP) at a mass ratio of 90.25:3:2:4.75, and the mixture was fully stirred and mixed to prepare a positive electrode slurry. The positive electrode slurry was coated on one side of the aluminum foil (the coating surface density was 0.8 mm 2 ), then drying and cold pressing to form a positive electrode active material layer (with a thickness of 0.05 mm) on one side of the aluminum foil (with a thickness of 15 μm), and finally punching to obtain a positive electrode sheet;

[0178] b. Preparation of negative electrode sheet:

[0179] A metal lithium sheet with a thickness of 0.5 mm is used as the negative electrode.

[0180] c. Preparation of isolation membrane:

[0181] Polyethylene was used as the isolation film (thickness 20 μm);

[0182] d. Preparation of electrolyte

[0183] Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1 to obtain a solvent, and a fully dried electrolyte salt LiPF 6 Dissolve in the above solvent, mix well to obtain an electrolyte with a concentration of 1 mol / L.

[0184] Assembly: stack a single positive electrode sheet, a single separator, and a single negative electrode sheet in order (the side of the positive electrode sheet where the positive active material layer is formed contacts the separator), place the separator between the positive and negative electrodes to isolate them, add electrolyte, and obtain a CR2032 button battery A (capacity ≤ 2 mAh) through pressure packaging (500 MPa).

[0185] The above coin-type full cell A was used as an experimental example to perform charge-discharge cycling at a rate of 0.1C at 25°C. The capacity (Q)-voltage (V) curve of the first cycle was recorded, and by differentiating it, the dQ / dV-V curve was obtained. At the same time, the dQ / dV-V curve of the control coin-type cell (the capacity compensation additive was not added to the positive electrode sheet, that is, lithium iron phosphate, acetylene black, and the binder polyvinylidene fluoride were mixed in a mass ratio of 95:3:2 during the preparation of the positive electrode sheet, and the rest was the same as the above coin-type cell) was obtained under the same conditions. By comparing the two curves, an additional peak position could be seen on the dQ / dV-V curve of the experimental example coin-type cell. This peak position was the characteristic peak position of the capacity compensation additive, and the ordinate corresponding to this peak position was the decomposition potential of the capacity compensation additive.

[0186] (2) Powder resistivity test

[0187] The current and voltage were measured on the powder sample using four probes, and the resistivity was calculated based on the current and voltage.

[0188] (3) First charge capacity test of the battery:

[0189] Coin-type cell B was prepared, which differed from coin-type cell A in that the capacity compensation additive was not added during the preparation of the positive electrode sheet. Lithium iron phosphate, acetylene black, and the binder polyvinylidene fluoride were dissolved in the solvent N-methylpyrrolidone (NMP) in a mass ratio of 95:3:2, and after being fully stirred and mixed evenly, a positive electrode slurry was prepared.

[0190] At 25°C, the above coin-type cell A was charged at a constant current density of 0.1C to 4.5V, and the first charge specific capacity Q of the battery was recorded A , and then coin-type cell B was charged at a constant current density of 0.1C to 4.5V, and the first charge specific capacity Q of the battery was recorded B , the first charge capacity = (Q A -W 1 Q B ) / W 2 , where in the positive electrode sheet of coin-type cell A, based on the total mass of lithium iron phosphate and the capacity compensation additive, the mass fraction of the capacity compensation additive is W 2 , and the proportion of lithium iron phosphate is W 1 .

[0191] (4) Cycle performance test of the lithium-ion battery:

[0192] The ambient temperature was controlled at 60°C, left standing for 2h, discharged at 1C to 2.5V, left standing for 5min, charged at 1C to 3.65V, left standing for 5min, and discharged at 1C to 2.5V. The discharge capacity was recorded as C 0Charge at 1C to 3.65V, stand still for 5 min, discharge at 1C to 2.5V, and stand still for 5 min. Perform 1000 cycles according to this process. The discharge capacity at the 1000th cycle is C 1 , the cycle capacity retention rate of the battery cell = C 1 / C 0 *100%.

[0193] Figure 7 is the comparison chart of the cycle curves of the batteries of Example 1, Comparative Example 1, and Comparative Example 6. It can be seen from Figure 7 that the capacity retention rate of the lithium-ion battery in Example 1 is significantly higher than that in Comparative Example 1 and Comparative Example 6 after 1000 cycles, indicating that adding a capacity compensation additive including a carbon material containing a catalyst to the positive electrode sheet in Example 1 can improve the cycle performance of the battery.

[0194] Figure 8 is the SEM image of the capacity compensation additive obtained in Example 1. Figure 9 is the distribution map of Ni element in the EDS energy spectrum of the capacity compensation additive obtained in Example 1 (test method reference GB / T 17359-2012). It can be seen from the figure that the distribution of Ni element on the surface of the capacity compensation additive is uniform, indicating that the carbon nanotubes containing nickel oxide are uniformly distributed on the surface of the capacity compensation agent and the nickel oxide is uniformly distributed on the carbon nanotubes.

[0195] Table 2

[0196]

[0197]

[0198] Conclusion: It can be seen from the data in Table 2 that the decomposition voltages of the capacity compensation agents in Examples 1-23 are significantly lower than those in Comparative Examples 1-6, and the first charge capacities and capacity retention rates of the batteries in Examples 1-23 are significantly higher than those in Comparative Examples 1-6. This indicates that the capacity compensation additive of the present application has a lower decomposition voltage, thereby improving the capacity and cycle performance of the battery.

[0199] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples. Embodiments having the same structure and the same function and effect as the technical idea within the scope of the technical solution of the present application are included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be thought of by those skilled in the art are applied to the embodiments, and other embodiments constructed by combining some constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A capacity compensation additive, characterized in that, it comprises a capacity compensator and a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator.

2. The capacity compensation additive according to claim 1, characterized in that, The catalyst-containing carbon material includes a carbon support and a catalyst, the catalyst being loaded on at least a part of the carbon support, and the catalyst includes M x Q y , where 1 ≤ x ≤ 6, 1 ≤ y ≤ 3, M includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, Mg or Cr, optionally, M includes at least one of Ni, Co or Fe, Q includes at least one of O, N, S or P, optionally, Q includes O and / or N.

3. The capacity compensation additive according to claim 2, characterized in that, Based on the total mass of the catalyst-containing carbon material, the mass proportion of the catalyst is 5%-20%, and optionally 5%-15%.

4. The capacity compensation additive according to claim 2 or 3, characterized in that, the particle size of the catalyst is 300nm - 1μm, and optionally 500nm - 800nm.

5. The capacity compensation additive according to any one of claims 1-4, characterized in that, Based on the total mass of the capacity compensation additive, the mass proportion of the catalyst-containing carbon material is 1%-20%, and optionally 5%-10%.

6. The capacity compensation additive according to any one of claims 1-5, characterized in that, The capacity compensator includes A a C b O c , where A includes Na and / or Li, 2 ≤ a ≤ 4, 1 ≤ b ≤ 6, 3 ≤ c ≤ 6.

7. The capacity compensation additive according to any one of claims 1-6, characterized in that, The capacity compensator includes a lithium supplementing agent, and the lithium supplementing agent includes Li 2 CO 3 、Li 2 C 2 O 4 、Li 2 C 4 O 4 、Li 2 C 4 O 6 or Li 2 C 3 O 5 and at least one of them. Optionally, the lithium supplementing agent includes Li 2 CO 3 、Li 2 C 2 O 4 or Li 2 C 4 O 4 and at least one of them.

8. The capacity compensation additive according to any one of claims 1-7, characterized in that, The capacity compensator includes a sodium supplement, and the sodium supplement includes Na 2 CO 3 、Na 2 C 2 O 4 、Na 2 C 4 O 4 、Na 2 C 6 O 6 or Na 4 C 6 O 6 or at least one of the following, and optionally, the sodium supplement includes Na 2 C 2 O 4 or Na 2 C 4 O 4 or at least one of the following.

9. The capacity compensation additive according to any one of claims 1-8, characterized in that, the volume average particle size Dv50 of the capacity compensation additive is 1μm - 20μm, and optionally 1μm - 10μm.

10. The capacity compensation additive according to any one of claims 1-9, characterized in that, Under 20MPa, the powder resistivity of the capacity compensation additive is less than or equal to 5Ω·cm, and optionally less than or equal to 1Ω·cm.

11. The capacity compensation additive according to any one of claims 1-10, characterized in that, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.5V, and optionally lower than or equal to 4.3V.

12. A method for preparing a capacity compensation additive, characterized in that, comprising: Coating a catalyst-containing carbon material on at least part of the surface of a capacity compensator to obtain a capacity compensation additive.

13. The method according to claim 12, characterized in that, Coating the catalyst-containing carbon material on at least part of the surface of the capacity compensator is carried out in the following manner: Spray-drying a slurry comprising a catalyst-containing carbon material and a capacity compensator, so that the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator.

14. The method according to claim 13, characterized in that, The spray-drying includes at least one of the following conditions: The concentration of the slurry comprising a capacity compensator and a catalyst-containing carbon material is 20g / L - 50g / L, and optionally 20g / L - 30g / L; The inlet air temperature is 120°C - 150°C; The outlet air temperature is 80°C - 100°C.

15. The method according to claim 13, characterized in that, Coating the catalyst-containing carbon material on at least part of the surface of the capacity compensator is carried out in the following manner: Electrospin a slurry comprising a catalyst-containing carbon material and a capacity compensator, such that the catalyst-containing carbon material coats at least a part of the surface of the capacity compensator.

16. The method according to claim 15, wherein, the electrospinning includes at least one of the following conditions: the concentration of the slurry comprising the capacity compensator and the catalyst-containing carbon material is 5 g / L - 20 g / L; the pushing speed of the spinneret is 0.3 mL / h - 1 mL / h; the voltage between the spinneret and the receiver is 15 kV - 18 kV; the distance between the spinneret and the receiver is 12 cm - 20 cm.

17. A positive electrode sheet, wherein, it includes the capacity compensation additive according to any one of claims 1 - 11 or the capacity compensation additive obtained by the method according to any one of claims 12 - 16.

18. The positive electrode sheet according to claim 17, wherein, the positive electrode sheet includes a positive electrode active material layer, and the positive electrode active material layer includes the capacity compensation additive.

19. The positive electrode sheet according to claim 18, wherein, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensation additive is 1% - 20%, and optionally 1% - 5%.

20. A battery, wherein, it includes the positive electrode sheet according to any one of claims 17 - 19.

21. An electrical device, wherein, the electrical device includes the battery according to claim 20.

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