Lithium supplement material, preparation method thereof and secondary battery

Abstract

The invention relates to a lithium supplementing material and a preparation method thereof and a secondary battery, the lithium supplementing material comprises a porous carrier, a gaseous lithium removing agent and a lithium-rich material, the porous carrier is provided with holes, the gaseous lithium removing agent is adsorbed and accommodated in the holes, and the lithium-rich material is combined with the porous carrier. The lithium supplement material has a good lithium removal effect.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to a lithium supplement material and a preparation method thereof, and a secondary battery. Background Art

[0002] During the first charging process of a lithium-ion battery, the negative electrode material permanently consumes more active Li from the positive electrode. + , forming a SEI film on the surface of the negative electrode, reducing the capacity and energy density of the lithium-ion battery. In order to make up for the lithium consumed in forming the SEI film, lithium replenishment technology can be used in lithium-ion batteries. Compared with negative electrode lithium replenishment, positive electrode lithium replenishment can directly add lithium replenishment materials into the positive electrode slurry without additional process improvements, and the cost is relatively low.

[0003] The lithium ion extraction efficiency and rate in existing lithium-supplementing materials are low, which greatly hinders their commercial application. Summary of the invention

[0004] The purpose of the present application is to provide a lithium supplement material and a preparation method thereof and a secondary battery, which can promote the decomposition of lithium-rich materials in the lithium supplement material, accelerate the release rate of lithium ions in the lithium-rich material, improve the release efficiency of lithium ions in the lithium-rich material, and improve the transmission power of lithium ions.

[0005] To achieve the purpose of this application, this application provides the following technical solutions:

[0006] In a first aspect, the present invention provides a lithium supplement material, comprising a porous carrier, a gaseous lithium removal agent and a lithium-rich material, wherein the porous carrier has pores, the gaseous lithium removal agent is adsorbed and accommodated in the pores, and the lithium-rich material is combined with the porous carrier.

[0007] In one embodiment, the gaseous delithiation agent includes at least one of NO2 and SO2.

[0008] In one embodiment, the porous carrier includes at least one of a carbon material, an organic polymer material, and a metal compound.

[0009] In one embodiment, the specific surface area of ​​the porous carrier is 200 m 2 / g~800m 2 / g.

[0010] In one embodiment, the pore volume of the porous carrier is 1.35 cm 3 / g~2.10cm 3 / g.

[0011] In one embodiment, the ratio of the volume of the gaseous delithiation agent to the pore volume of the porous carrier is 0.5-1.

[0012] In one embodiment, the D50 particle size of the porous carrier is 1 um to 5 um.

[0013] In one embodiment, the D50 particle size of the lithium-rich material is 500nm to 1um.

[0014] In one embodiment, the lithium-rich material surrounds and wraps around the surface of the porous carrier, or the lithium-rich material blocks the pores.

[0015] In one embodiment, the lithium-rich material is doped with non-lithium metal elements, and the non-lithium metal elements include at least one of Na and K; and / or the molar ratio of the non-lithium metal element to Li contained in the lithium-rich material is x:(1-x), wherein 0<x<0.5.

[0016] In one embodiment, the lithium-supplementing material further includes a catalyst, and at least a portion of the lithium-rich material is connected to the catalyst.

[0017] In one embodiment, the catalyst includes at least one of metal selenide, metal oxide, metal carbide, and metal nitride.

[0018] In one embodiment, the D50 particle size of the catalyst is 2 nm to 20 nm.

[0019] In one embodiment, the mass ratio of the lithium-rich material, the porous carrier and the catalyst is 100:(25-100):(5-20).

[0020] In a second aspect, the present invention also provides a method for preparing a lithium-supplementing material, comprising: passing a gaseous delithiation agent into a porous carrier so that the gaseous delithiation agent is adsorbed and contained in the pores of the porous carrier; combining a lithium-rich material with the porous carrier loaded with the gaseous delithiation agent to obtain a lithium-supplementing material.

[0021] In one embodiment, the method further comprises: loading the catalyst on a porous carrier.

[0022] In one embodiment, the lithium-rich material is combined with the porous carrier loaded with the gaseous delithiation agent, and further includes: the lithium-rich material is doped with non-lithium metal elements.

[0023] In a third aspect, the present invention further provides a secondary battery comprising a positive electrode, a negative electrode and an electrolyte arranged between the positive electrode and the negative electrode, wherein the positive electrode comprises a lithium-supplementing material as described in any one of the various embodiments of the first aspect, or comprises a lithium-supplementing material obtained by the preparation method of the lithium-supplementing material as described in any one of the various embodiments of the second aspect.

[0024] The lithium supplement material provided by the present invention uses a porous carrier as a matrix, and utilizes the pores of the porous carrier to accommodate a gaseous lithium-removing agent. The porous carrier is also combined with a lithium-rich material. The advantages of the lithium supplement material include: 1) the gaseous lithium-removing agent accommodated in the pores reacts with the lithium-rich material, which can promote the decomposition of the lithium-rich material, accelerate the release rate of lithium ions, and improve the release efficiency of lithium ions; 2) the gaseous lithium-removing agent after the reaction is reduced to anions, which can be used as an electrolyte to accelerate the transmission of lithium ions and improve the power of lithium ion transmission; 3) the porous carrier has strong conductivity, and the use of the porous carrier as a matrix can improve the overall conductivity of the lithium supplement material; 4) the pores on the porous carrier are conducive to providing space for the gaseous lithium-removing agent to flow and react, and after the lithium-rich material produces gas, the gas is ensured to flow in an orderly manner. After the reaction of the gaseous lithium-removing agent, a certain negative pressure will be formed in the porous carrier. The gas that cannot be discharged during battery formation can be adsorbed in the porous carrier, and will not cause battery bulging, thereby improving the stability and safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is a schematic cross-sectional view of a lithium supplement material according to an embodiment;

[0027] Figure 2 is a partial schematic diagram of a lithium supplement material of an embodiment;

[0028] Figure 3 is a partial schematic diagram of a lithium supplement material according to another embodiment;

[0029] Figure 4 is a partial schematic diagram of a lithium supplement material according to another embodiment;

[0030] Figure 5 is a partial schematic diagram of a lithium supplement material according to another embodiment;

[0031] Figure 6 is a flow chart for preparing a lithium supplement material according to an embodiment;

[0032] Figure 7 is a flow chart of step S00 of one embodiment;

[0033] Figure 8 is a flow chart of step S20 of one embodiment;

[0034] Fig. 9This is a scanning electron microscope image of Example 1.

[0035] Description of reference numerals:

[0036] 10-porous carrier, 11-pores, 111-first pores, 20-gaseous delithiation agent, 30-lithium-rich material, 40-catalyst. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0039] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.

[0040] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0041] Pore ​​volume: the total volume of pores per unit mass of porous solid material. Pore volume is usually calculated from particle density ρp and true density ρt according to the formula Vg = 1 / ρp-1 / ρt. In the formula, 1 / ρp is the apparent volume of 1g of porous solid, 1 / ρt is the volume of the skeleton in 1g of porous solid, and the difference between the two is equal to the pore volume.

[0042] D50 particle size: D50 particle size refers to the particle size corresponding to 50% of the cumulative particle size distribution percentage in the particle size distribution curve. In other words, D50 particle size divides the particle population into two equal parts: half of the particles have a particle size larger than D50, and the other half have a particle size smaller than D50.

[0043] The lithium supplement material in the embodiment of the present invention is introduced below.

[0044] Please refer to Figures 1 to 5An embodiment of the present invention provides a lithium-supplementing material, which includes a porous carrier 10, a gaseous delithiation agent 20 and a lithium-rich material 30. The porous carrier 10 has pores 11, the gaseous delithiation agent 20 is adsorbed and accommodated in the pores 11, and the lithium-rich material 30 is combined with the porous carrier 10.

[0045] Among them, the lithium-rich material 30 is the main body for lithium supplementation, which can contribute a large amount of lithium ions. During the first charging process, the lithium (Li) in the lithium-rich material can be released and migrated to the negative electrode of the battery to offset the irreversible lithium loss caused by the formation of the SEI film, thereby increasing the total capacity and energy density of the battery. However, in most existing lithium supplementation materials, due to the limitations of the carrier and the catalyst, it is difficult for lithium ions in the lithium-rich material to be removed, and it is impossible to completely remove lithium, resulting in a poor lithium supplementation effect of the lithium-rich material, which greatly hinders its commercial application. Therefore, how to promote the removal of lithium ions in lithium-rich materials has become the key.

[0046] The lithium supplement material provided by the present invention uses a porous carrier 10 as a matrix, and uses the pores 11 of the porous carrier 10 to accommodate a gaseous lithium removal agent 20. The porous carrier 10 is also combined with a lithium-rich material 30. The advantages of the lithium supplement material include: 1) the gaseous lithium removal agent 20 accommodated in the pores 11 reacts with the lithium-rich material 30, which can promote the decomposition of the lithium-rich material 30, accelerate the release rate of lithium ions, and improve the release efficiency of lithium ions; 2) the gaseous lithium removal agent 20 after the reaction is reduced to anions, which can be used as an electrolyte to accelerate the transmission of lithium ions and improve the efficiency of lithium ion release. Ion transmission power; 3) The porous carrier 10 has a strong electrical conductivity. Using the porous carrier 10 as a matrix can improve the overall electrical conductivity of the lithium supplement material; 4) The holes 11 on the porous carrier 10 are conducive to providing space for the gaseous delithiation agent 20 to flow and react, and after the lithium-rich material 30 produces gas, it ensures the orderly flow of gas. After the gaseous delithiation agent reacts, a certain negative pressure will be formed in the porous carrier. The gas that cannot be discharged during battery formation can be adsorbed in the porous carrier, which will not cause battery bulging, thereby improving the stability of the material and the safety of the battery.

[0047] The porous carrier 10 is the main body for loading the lithium-rich material 30 and the gaseous delithiation agent 20. The holes 11 on the porous carrier 10 can provide a storage space for the gaseous delithiation agent 20 and the lithium-rich material 30. Optionally, the porous carrier 10 has excellent electrical conductivity, and the lithium-rich material 30 loaded on the porous carrier 10 can improve its conductivity. In addition, the holes 11 on the porous carrier 10 can improve the stability of the lithium-rich material 30 and the gaseous delithiation agent 20 loaded on the porous carrier 10. On the other hand, the holes 11 bring a larger specific surface area, thereby increasing the load of the two. At the same time, the holes 11 on the porous carrier 10 can divert the gas generated by the lithium-rich material 30 after discharge, and avoid the gas generated by the lithium-rich material 30 from accumulating in the material, thereby reducing the impact of gas production on the battery, and ultimately achieving the purpose of improving battery performance.

[0048] The gaseous delithiation agent 20 has the function of assisting the lithium-rich material 30 in delithiation. The gaseous delithiation agent 20 is contained in the pores 11 of the porous carrier 10, and can react with the lithium-rich material 30, thereby promoting the decomposition of the lithium-rich material 30. Optionally, the gaseous delithiation agent 20 is a reducing gas, that is, the gaseous delithiation agent 20 can be reduced by an oxidant and lose electrons. The gaseous delithiation agent 20 undergoes an oxidation-reduction reaction with the lithium-rich material 30, and the reaction process can promote the decomposition of the lithium-rich material 30, accelerate the lithium ion extraction rate, and also improve the lithium ion extraction efficiency.

[0049] For example, a unit lithium-rich material 30 has 10 parts of lithium ions. Without adding the gaseous delithiation agent 20, the unit lithium-rich material 30 can only release 6 to 8 parts of lithium ions. After adding the gaseous delithiation agent 20, the unit lithium-rich material 30 can release 9 to 10 parts of lithium ions. Therefore, the gaseous delithiation agent 20 can effectively promote the release of lithium ions in the lithium-rich material 30 to improve the release efficiency of lithium ions.

[0050] Optionally, the gaseous delithiation agent 20 includes at least one of NO2 and SO2.

[0051] In a specific embodiment, the gaseous lithium removal agent 20 is NO2. When NO2 reacts with the lithium-rich material 30, it loses an electron and is reduced to nitrite, which can first induce the removal of a portion of lithium ions in the lithium-rich material 30 to promote the decomposition reaction. At the same time, the nitrite formed by the reduction of NO2 can be used as an electrolyte additive to accelerate the transmission of lithium ions and improve the power of lithium ion transmission.

[0052] The reaction process of the gaseous delithiation agent 20 is as follows (taking the gaseous delithiation agent 20 as NO2 as an example):

[0053] NO2-e→NO2-;

[0054] Further, the reaction equation of the gaseous delithiation agent 20 and the lithium-rich material 30 is as follows (taking the gaseous delithiation agent 20 as NO2 and the lithium-rich material 30 as lithium oxalate as an example):

[0055] NO2+Li2C2O4→Li++NO2-+CO2.

[0056] Unlike the catalyst in the prior art, the main function of the catalyst is to catalytically reduce the lithium desorption potential of the lithium-rich material 30 and reduce the lithium desorption platform of the lithium-rich material 30, but the improvement of the lithium ion removal in the lithium-rich material 30 is small. At the same time, unlike the solid or liquid lithium desorption agent in the prior art, the gaseous lithium desorption agent 20 has stronger fluidity, which is convenient for being better accommodated in the pores 11 of the porous carrier 10. The gaseous lithium desorption agent 20 can also better penetrate into the tiny pores that are difficult for the solid lithium desorption agent and the liquid lithium supplement agent to reach, and the lithium desorption effect is better.

[0057] In some embodiments of the present invention, the chemical formula of the lithium-rich material 30 is Li x1 C y1 O z1 , where 0<x1≤2,y1> 0, z1>0. In some embodiments of the present application, the lithium-rich material 30 may be one or more of Li2C3O3, Li2C4O4, Li2C6O6, Li2C3O5, Li2C2O4 and Li2C4O6. It can be understood that the lithium-rich material 30 of lithium oxalate has a higher theoretical capacity (>525mAhg -1 ) and good air stability, it is considered to be an attractive cathode pre-lithiation additive. However, it has a high delithiation potential (>4.7V), which cannot match most commercial cathode materials, and its poor conductivity greatly hinders its commercial application.

[0058] In some embodiments of the present invention, the lithium-rich material 30 also includes other lithium-supplementing materials with higher delithiation potentials, mainly including lithium-supplementing materials with delithiation potentials above 4V, such as Li2O (delithiation potential 4.5V), Li2O2 (delithiation potential 4.3V), LiOH (delithiation potential 4.8V), Li4SiO4 (delithiation potential 4.5V), Li3PO4 (delithiation potential exceeding 4V), Li2CO3 (delithiation potential 4.7V), and Li5FeO4 (delithiation potential 4V). These lithium-rich materials 30 also have higher capacity, but these lithium-rich materials 30 require higher charging voltages for delithiation, and there is a technical problem of high platform voltage. At the same time, the higher voltage also causes the lithium-rich material 30 to produce oxygen when the lithium-ion battery is charged and discharged for the first time. The generated oxygen is further oxidized to cause the electrolyte to oxidize and decompose, thereby reducing the safety and performance of the lithium-ion battery. These lithium-rich materials 30 with higher delithiation potentials are also difficult to compound with conventional positive electrode materials (such as lithium iron phosphate with a delithiation potential of about 3.5V), which limits the wide application of lithium supplement materials. Therefore, the present invention provides a porous carrier 10 with pores, and the gaseous delithiation agent 20 is contained in the pores of the porous carbon carrier, and the gaseous delithiation agent 20 reacts with the lithium-rich material 30, which can effectively promote the release rate of lithium ions in the lithium-rich material 30, improve the release efficiency of lithium ions in the lithium-rich material 30, and improve the utilization rate of the lithium-rich material 30.

[0059] The lithium-rich material 30 mentioned above may be undoped or modified by doping, or may be surface coated, pre-lithiated, etc. These lithium-rich materials 30 have high theoretical capacity and structural stability, can provide sufficient lithium ions, effectively supplement the irreversible lithium ions consumed by the formation of SEI film in the negative electrode, and improve the initial efficiency and overall electrochemical performance of the battery.

[0060] Optionally, the lithium-rich material 30 is bonded to the outer surface of the porous carrier 10 , and / or the lithium-rich material 30 is bonded to the inner wall surface of the pores 11 of the porous material, without specific limitation.

[0061] In a specific embodiment, the lithium-rich material 30 is Li2C2O4 (lithium oxalate). Li2C2O4 has a high theoretical capacity and good air stability. The gaseous delithiation agent 20 carried by the porous carrier 10 reacts with Li2C2O4. When the gaseous delithiation agent 20 loses electrons and is reduced, the oxalate of Li2C2O4 is oxidized and generates CO2, which can first induce the removal of a portion of lithium ions in the lithium-rich material 30, promote the decomposition reaction, and reduce the delithiation potential of the lithium-rich material 30. At the same time, the pore structure of the porous carrier 10 is conducive to the circulation of CO2 gas, ensuring the stability of the material structure.

[0062] In one embodiment, the porous carrier 10 includes at least one of a carbon material, an organic polymer material, and a metal compound. Optionally, the porous carrier 10 may be a porous carbon carrier, a porous fiber material, a metal organic framework (MOF) material, or a porous metal oxide, and any one or more combinations thereof, without limitation.

[0063] In a specific embodiment, the porous carrier 10 may be a porous carbon carrier. The pore structure on the porous carbon carrier can provide a storage space for the gaseous delithiation agent 20 and the lithium-rich material 30. Since the porous carbon carrier is essentially a carbon material, the porous carbon carrier has excellent electrical conductivity, and the lithium-rich material 30 loaded on the porous carbon carrier can improve its electrical conductivity.

[0064] In one embodiment, the porous carbon support is doped with non-carbon heteroatoms, and the non-carbon heteroatoms include at least one of N, P, and S.

[0065] Specifically, during the preparation process of the porous carbon carrier, organic matter containing heteroatoms can be introduced to achieve the purpose of heteroatom doping. In a specific embodiment, the heteroatom doped in the porous carbon carrier can be N element. The advantage of N doping is that it can create defect sites, which effectively regulate the electronic structure and stability of the active site, enhance the charge transfer of the interface, and accelerate the delithiation reaction kinetics of the material.

[0066] In one embodiment, the porous carbon carrier is provided with slits, and the slits extend in a curved manner on the surface of the porous carbon carrier.

[0067] Specifically, the gaps on the porous carbon carrier are formed on the surface of the porous carbon carrier, and the size of the gaps is smaller than the holes 11 mentioned above. The gaps on the porous carbon carrier can further increase the specific surface area of ​​the porous carbon carrier, thereby improving the overall conductivity of the material.

[0068] In a specific embodiment, the gaps may be those left after the porous carbon carrier is sintered during the preparation process. By controlling the sintering process of the porous carbon carrier, a certain number of gaps with a certain size may be produced.

[0069] In one embodiment, the shape of the porous carrier 10 includes at least one of a sphere, a rod, a tube, and a line, and is not specifically limited. In a specific embodiment, the porous carrier 10 is a porous carbon carrier, and the porous carbon carrier can be a carbon nanosphere, a carbon nanotube, a carbon nanofiber, etc. Optionally, the shape of the porous carbon carrier is spherical, that is, the porous carbon carrier is a carbon nanosphere.

[0070] In one embodiment, the porous carrier 10 is spherical in shape, and the D50 particle size of the porous carrier 10 is 1um to 5um. When the D50 particle size of the porous carrier 10 is within the above range, the agglomeration of the porous carrier 10 can be avoided, and the difficulty of preparation can be reduced, while reducing the volume requirements for the gaseous delithiation agent 20 and the lithium-rich material 30. When the D50 particle size of the porous carrier 10 is too small, the agglomeration of the porous carrier 10 is serious, and the volume requirements for the loaded gaseous delithiation agent 20 and the lithium-rich material 30 are higher, which not only affects the loading capacity of the porous carbon carrier, but also increases the difficulty of preparing the lithium supplement material as a whole; when the D50 particle size of the porous carrier 10 is too large, the conductivity of the porous carrier 10 decreases, and the specific surface area decreases. Optionally, the D50 particle size of the porous carrier 10 can be 1um, 1.5um, 2um, 2.5um, 3um, 3.5um, 4um, 4.5um, 5um.

[0071] In one embodiment, the porosity of the porous carrier 10 is 55% to 85%. When the porosity of the porous carrier 10 is within the above range, the porous carrier 10 has a larger space to accommodate the gaseous delithiation agent 20 and the lithium-rich material 30, and ensures the structural stability of the porous carrier 10. When the porosity of the porous carrier 10 is too small, there are fewer pores on the porous carrier 10, the gaseous delithiation agent 20 and the lithium-rich material 30 have less capacity, the bonding strength between the two on the porous carrier 10 decreases, and the specific surface area of ​​the porous carrier 10 is small, resulting in a decrease in the conductivity of the material. When the porosity of the porous carrier 10 is too large, the structural stability of the porous carrier 10 deteriorates, and the overall strength of the lithium supplement material is poor. Optionally, the porosity of the porous carrier 10 can be 55%, 60%, 65%, 68%, 70%, 75%, 80%, 85%.

[0072] In one embodiment, the specific surface area of ​​the porous carrier 10 is 200 m 2 / g~800m 2 / g. The present invention can further form gaps on the surface of the carrier by making the carrier material into a porous structure, thereby increasing the complexity of the carrier surface, thereby maximizing the surface area of ​​the porous material, thereby obtaining a porous carrier 10 with a high specific surface area. When the specific surface area of ​​the porous carrier 10 is within the above range, the loading amount of the lithium-rich material 30 and the gaseous delithiation agent 20 can be increased, thereby increasing the lithium replenishment capacity of the lithium replenishment material. When the specific surface area of ​​the porous carrier 10 is too small, the loading amount of the lithium-rich material 30 and the gaseous delithiation agent 20 is small, not only the capacity improvement is limited, but also the effect of the gaseous delithiation agent 20 is weak; when the specific surface area of ​​the porous carrier 10 is too large, it is difficult for the porous carbon carrier to suppress the lattice volume expansion of the lithium-rich material 30. Optionally, the specific surface area of ​​the porous carrier 10 can be 200m 2 / g、300m 2 / g, 400m2 / g、500m 2 / g、600m 2 / g、700m 2 / g、800m 2 / g.

[0073] In one embodiment, the pore volume of the porous carrier 10 is 1.35 cm 3 / g~2.10cm 3 / g. When the pore volume of the porous carrier 10 is within the above range, the adsorption capacity of the porous carrier 10 is relatively strong, and the structural stability of the porous carrier 10 can be ensured at the same time. When the pore volume of the porous carrier 10 is too small, the porous carrier 10 can absorb less gaseous delithiation agent 20 and lithium-rich material 30, which is not conducive to improving the lithium replenishment effect of the lithium replenishment material. When the pore volume of the porous carrier 10 is too large, the volume of the pores 11 of the porous carrier 10 accounts for too large a proportion, resulting in poor structural stability of the porous carrier 10 and poor overall strength of the lithium replenishment material. Optionally, the pore volume of the porous carrier 10 can be 1.35cm 3 / g, 1.40cm 3 / g, 1.45cm 3 / g, 1.50cm 3 / g, 1.55cm 3 / g, 1.60cm 3 / g, 1.65cm 3 / g, 1.70cm 3 / g, 1.75cm 3 / g, 1.80cm 3 / g, 1.85cm 3 / g, 1.90cm 3 / g, 1.95cm 3 / g, 2cm 3 / g, 2.05cm 3 / g, 2.10cm 3 / g.

[0074] In one embodiment, the ratio of the volume of the gaseous delithiation agent 20 to the pore area of ​​the porous carrier 10 is 0.5 to 1. The pore area of ​​the porous carrier 10 is the total volume of the pores of the porous carrier 10. When the ratio of the volume of the gaseous delithiation agent 20 to the pore area of ​​the porous carrier 10 is within the above range, the absorption capacity of the gaseous delithiation agent 20 adsorbed by the porous carrier 10 is appropriate, which can effectively promote the decomposition of the lithium-rich material 30, accelerate the release of lithium ions, and reduce the decomposition potential of the lithium-rich material 30. When the ratio of the volume of the gaseous delithiation agent 20 to the pore area of ​​the porous carrier 10 is too small, the absorption capacity of the gaseous delithiation agent 20 adsorbed in the porous carrier 10 is insufficient, and the decomposition potential of the lithium-rich material 30 cannot be effectively reduced. Optionally, the ratio of the volume of the gaseous delithiation agent 20 to the pore area of ​​the porous carrier 10 can be 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 1.

[0075] In one embodiment, the lithium-rich material 30 surrounds and wraps around the surface of the porous material or the lithium-rich material 30 blocks the pores 11 .

[0076] Specifically, Figure 2 and Figure 3 As shown, the porous carrier 10 has open pores 11, which are connected to the external space, so that the external material (such as the gaseous lithium removal agent 20) can be easily filled into the pores 11. It can be understood that the surface of the porous carrier 10 includes the wall surface of the open pores 11 and the outer surface of the porous carrier 10, and the lithium-rich material 30 is at least blocked at the opening of the open pores 11. Figure 2 As shown, the gaseous delithiation agent 20 is prevented from overflowing from the open pores 11, resulting in a reduced capacity of the gaseous delithiation agent 20 in the porous carrier 10, which is unable to fully react with the lithium-rich material 30, and the effect of reducing the decomposition potential is poor. Figure 3 As shown, the lithium-rich material 30 can also be coated on the outer surface of the porous carrier 10 and / or the wall of the pores 11 to fully contact the gaseous delithiation agent 20 and the porous carrier 10, thereby improving the conductivity of the lithium-rich material 30 and reducing the delithiation potential of the lithium-rich material 30.

[0077] In a specific implementation, please refer to Figure 2 The pores 11 of the porous carrier 10 include a first pore 111, which is an open pore. The first pore 111 contains a gaseous delithiation agent 20, and the lithium-rich material 30 is blocked at the opening of the first pore 111. In another specific embodiment, please refer to Figure 3 Part of the lithium-rich material 30 blocks the first hole 111, and part of the lithium-rich material 30 is coated on the outer surface of the porous carrier 10. The above methods are all possible and are not specifically limited. Such a configuration can ensure the lithium replenishing capacity of the lithium replenishing material, enhance the conductivity of the lithium-rich material 30, and also ensure that the gaseous de-lithium agent 20 is contained in the pores 11 of the porous material and will not overflow from the pores 11.

[0078] In one embodiment, the D50 particle size of the lithium-rich material 30 is 500nm to 1um. When the particle size of the lithium-rich material 30 is within the above range, the agglomeration of the lithium-rich material 30 can be avoided, and the difficulty of combining the lithium-rich material 30 with the porous carrier 10 will be reduced. When the D50 particle size of the lithium-rich material 30 is too small, the agglomeration of the lithium-rich material 30 is serious, and the pores 11 of the porous carrier 10 cannot be effectively blocked, which may cause the gaseous delithiation agent 20 to overflow, increasing the difficulty of preparing the lithium-supplementing material as a whole; when the particle size of the lithium-rich material 30 is too large, the lithium-rich material 30 that can be loaded on the surface of the porous carrier 10 becomes less, which is not conducive to the combination of the porous carrier 10 and the gaseous delithiation agent 20 with the lithium-rich material 30. Optionally, the D50 particle size of the lithium-rich material 30 can be 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 1um.

[0079] In one embodiment, the lithium-rich material 30 is doped with non-lithium metal elements. Doping non-lithium metal element atoms into the Li position can cause lattice defects in the lithium-rich material 30, increase the vacancy concentration of Li, and improve the conductivity of the lithium-rich material 30. In addition, the atomic radius of the non-lithium metal element is larger than the atomic radius of Li, which can expand the interlayer spacing of the crystal structure of the lithium-rich material 30, reduce the intermolecular force, expand the lithium ion transmission channel, and reduce the polarization voltage required for the decomposition of the lithium-rich material 30. At the same time, the non-lithium metal ions released after the lithium-rich material 30 is delithiated can be combined with anions in the electrolyte, as an electrolyte additive to accelerate the transmission of lithium ions and improve the lithium ion transmission power.

[0080] In some embodiments of the present invention, the non-lithium metal element includes at least one of Group IA metals, Group IIA metals and Group IIIA metals. Optionally, the non-lithium metal element includes at least one of Na, K, Mg, Ca and Al.

[0081] In a specific embodiment, the lithium-rich material 30 is lithium oxalate, and the non-lithium metal element is K. K atoms are doped into the Li position to produce lattice defects in lithium oxalate, increase the vacancy concentration of Li, improve the conductivity of the lithium supplement, and at the same time expand the interlayer spacing of the lithium oxalate crystal structure, reduce the intermolecular force, expand the lithium ion transmission channel, and reduce the polarization voltage required for the decomposition of the lithium supplement. In addition, the K released after lithium oxalate is de-lithiated + The ions can combine with the anions formed after the gaseous delithiation agent 20 is reduced, and serve as an electrolyte to accelerate the transmission of lithium ions and improve the power of lithium ion transmission.

[0082] In one embodiment, the molar ratio of the non-lithium metal element to the Li contained in the lithium-rich material is x:(1-x), wherein 0<x<0.5. The molar ratio of the non-lithium metal element to lithium satisfies the above relationship, and the atomic doping of the non-lithium metal element occupies the Li position, which can cause lattice defects in the lithium-rich material 30, increase the Li vacancy concentration, and improve the conductivity of the lithium-supplementing material. At the same time, the interlayer spacing of the lithium oxalate crystal structure is expanded, the intermolecular force is reduced, and the lithium ion transmission channel is expanded. When the doping amount of the non-lithium metal element is too high, that is, when x is too large, the lithium-supplementing capacity of the lithium-supplementing material will be reduced. Optionally, the molar ratio of the non-lithium metal element to the Li contained in the lithium-rich material can be 0.01:0.99, 0.05:0.95, 0.1:0.9, 0.2:0.8, 0.3:0.7, 0.4:0.6, 0.45:0.55, 0.49:0.51.

[0083] In one implementation, please refer to Figure 4 and Figure 5 The lithium-supplementing material further includes a catalyst 40 , and at least a portion of the lithium-rich material 30 is connected to the catalyst 40 .

[0084] The catalyst 40 has a catalytic effect and is used to catalytically reduce the delithiation potential of the lithium-rich material 30. It should be explained that among the existing commercial lithium-rich materials, most lithium-rich materials have a higher capacity, but because the delithiation potential of the lithium-rich material does not match the voltage of the existing commercial positive electrode material, the lithium-rich material cannot fully release its capacity during the use of the battery. Therefore, by adding a catalyst 40 to the lithium-supplementing material to reduce the activation energy of the reaction, the reaction rate is increased. The addition of the catalyst 40 can reduce the delithiation potential of the lithium-rich material 30 to varying degrees, so that it can match the existing commercial positive electrode materials.

[0085] In one implementation, please refer to Figure 4 The catalyst 40 is connected to the outer surface of the porous carrier 10 and / or to the wall of the hole 11, and the catalyst 40 forms a catalytic film layer. Part of the lithium-rich material 30 is connected to the porous carrier 10 through the catalytic film layer.

[0086] Specifically, the catalyst 40 is in a granular form, and a plurality of granular catalysts 40 are continuously laid on the porous carrier 10, and a catalytic film layer is formed on the outer surface of the porous carrier 10 and the wall surface of the hole 11. It can be understood that the porous carrier 10 has open holes 11, and the holes 11 are connected to the external space, so the catalyst 40 can be attached to the wall surface of the hole 11; and a plurality of granular catalysts 40 are continuously connected to form a film layer, and the catalytic film layer covers the inner surface and the outer surface of the porous carrier 10.

[0087] In a specific embodiment, Figure 4As shown, the catalyst 40 is attached to the wall of the hole 11 and forms a catalytic film layer. The lithium-rich material 30 is connected to the catalytic film layer and blocks the opening of the hole 11, so that the gaseous delithiation agent 20 and the catalyst 40 are both contained in the hole 11. It should be explained that in the present invention, the catalyst 40 can be formed on the porous carrier 10 before the lithium-rich material 30, and then after the catalyst 40 forms a catalytic film layer, the lithium-rich material 30 is prepared on the porous carbon carrier loaded with the catalyst 40.

[0088] In one embodiment, the catalyst 40 is generated in situ on the porous carrier 10. The catalyst 40 provided by the present invention can be formed in situ on the porous carrier 10 by reacting a compound precursor. In a specific preparation method, a porous carrier 10 can be provided in advance, and then the porous carrier 10 and the compound precursor are mixed, and the compound precursor is attached to the porous carrier 10, thereby promoting the conversion of the compound precursor into the catalyst 40.

[0089] By in-situ growing the catalyst 40 on the surface of the porous carrier 10, the catalyst 40 can fully contact the porous carrier 10 and obtain a larger contact area, thereby exposing more active sites on the porous carrier 10, improving the conductivity of the porous carrier 10, and improving the atomic utilization of the catalyst 40.

[0090] In a specific embodiment, Figure 5 As shown, the catalyst 40 is granular, and a plurality of granular catalysts 40 are randomly distributed in the pores 11 of the porous carrier 10 , part of the lithium-rich material 30 blocks the openings of the pores 11 , and part of the lithium-rich material 30 fills the pores 11 and is connected to the catalyst 40 .

[0091] Optionally, the catalyst 40 and the gaseous delithiation agent 20 may be contained in the same hole 11 of the porous carrier 10, and / or, the hole 11 may contain only the catalyst 40 or the gaseous delithiation agent 20. The above methods are all possible and are not specifically limited. In a specific embodiment, Figure 1 As shown, some of the holes 11 contain the catalyst 40 and the gaseous delithiation agent 20 , some of the holes 11 contain only the catalyst 40 , and some of the holes 11 contain only the gaseous delithiation agent 20 .

[0092] In one embodiment, the catalyst 40 includes at least one of metal selenide, metal oxide, metal carbide, and metal nitride. In a specific embodiment, the catalyst 40 includes a metal oxide, which may be a selenide, and the metal selenide may be cobalt oxide, molybdenum oxide, etc. In other embodiments, the catalyst 40 includes a metal selenide, a metal carbide, a metal nitride, etc., and may be molybdenum selenide, nickel selenide, cobalt selenide, copper selenide, iron carbide, titanium carbide, cobalt nitride, etc.

[0093] In one embodiment, the D50 particle size of the catalyst 40 is 2nm to 20nm. When the particle size of the catalyst 40 is within the above range, it can ensure that the catalyst 40 can be accommodated in the hole 11, and it can also reduce the difficulty of preparing the catalyst 40 and avoid the agglomeration of the catalyst 40. When the particle size of the catalyst 40 is too small, the difficulty of preparing the catalyst 40 increases, and the agglomeration of the catalyst 40 is serious, which affects the performance of its catalytic performance; when the particle size of the catalyst 40 is too large, the catalyst 40 is difficult to fill into the hole 11, or it is easy to cause clogging of the hole 11, and the catalytic effect of the catalyst 40 on the lithium-rich material 30 is reduced. Optionally, the D50 particle size of the catalyst 40 can be 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 12nm, 14nm, 16nm, 18nm, 20nm.

[0094] In one embodiment, the mass ratio of the lithium-rich material 30, the porous carrier 10 and the catalyst 40 is 100: (25-100): (5-20). When the mass ratio of the three materials is within the above range, the lithium replenishment capacity of the lithium replenishment material can be ensured, and the catalytic effect of the catalyst 40 can be fully exerted, and the conductivity of the material can be ensured, and the delithiation potential of the lithium-rich material 30 can be reduced. When the mass of the porous carrier 10 is too small, it is difficult for the porous carrier 10 to provide a large load space, which will result in too little loading of other materials on a single porous carrier 10. When the mass ratio of the catalyst 40 is too small, the catalytic effect and conductivity of the catalyst 40 are poor. When the mass ratio of the above two materials is too large, it will further reduce the lithium-rich material 30 and make it difficult to exert more battery capacity, thereby reducing the energy density of the battery. Optionally, the mass ratio of the lithium-rich material 30, the porous carrier 10 and the catalyst 40 can be 100:25:(5-20), 100:40:(5-20), 100:50:(5-20), 100:65:(5-20), 100:80:(5-20), 100:100:(5-20), 100:(25-100):5, 100:(25-100):10, 100:(25-100):12, 100:(25-100):15, 100:(25-100):16, 100:(25-100):18, 100:(25-100):20.

[0095] In one embodiment, the present invention also provides a method for preparing a lithium supplement material, please refer to Figure 6 , including the following steps:

[0096] In step S10, a gaseous delithiation agent is introduced into the porous carrier, so that the gaseous delithiation agent is adsorbed and contained in the pores of the porous carrier.

[0097] Step S20, combining the lithium-rich material with a porous carrier loaded with a gaseous delithiation agent to obtain a lithium-supplementing material.

[0098] Optionally, the porous carrier may be the activated carbon provided in the above embodiment, and the specific structure and shape of the activated carbon will not be described in detail herein.

[0099] In the specific embodiment, please refer to Figure 6 , also includes:

[0100] Step S00, loading the catalyst onto a porous carrier, wherein the catalyst is contained in the pores of the porous carrier.

[0101] In the specific embodiment, please refer to Figure 7 Step S00, loading the catalyst on a porous carrier, wherein the catalyst is contained in the pores of the porous carrier, specifically comprising:

[0102] Step S01, oscillating and impregnating the activated carbon in the impregnation liquid A, filtering out the activated carbon after impregnation, and washing, drying and roasting the activated carbon.

[0103] Step S02, dissolving the catalyst precursor in solvent A to form an impregnation liquid B, impregnating the activated carbon in the impregnation liquid B, filtering out the activated carbon after impregnation, and drying the activated carbon.

[0104] Step S03, immersing the activated carbon in the impregnation liquid C, filtering out the activated carbon after the impregnation, and drying and calcining the activated carbon to obtain a porous carrier loaded with a catalyst.

[0105] Optionally, in step S01, the impregnation solution A (acid impregnation) is an aqueous solution of nitric acid with a concentration of 2M, and oscillation or stirring is maintained during the impregnation process; the oscillation impregnation time can be 48 hours, the drying temperature can be 80°C to 120°C, the roasting atmosphere can be air, the calcination temperature can be 300°C to 500°C, and the roasting time can be 4 hours.

[0106] Optionally, in step S02, the catalyst precursor may be cobalt acetate hexahydrate, solvent A may be deionized water, and cobalt acetate hexahydrate is dissolved in deionized water to form an impregnation solution B (transition metal salt impregnation); the impregnation time may be 3h to 6h, and the drying temperature may be 80°C to 120°C.

[0107] Optionally, in step S03, potassium hydroxide is dissolved in deionized water to form an impregnation solution C (alkaline impregnation); the impregnation time can be 3h to 6h, the drying temperature can be 80°C to 120°C, the annealing temperature can be 300°C to 500°C, the roasting atmosphere can be an inert gas such as nitrogen, and the annealing time can be 4h.

[0108] It should be explained that the catalyst prepared by the above steps can be cobalt oxide (CoO), but the above steps can also be used to prepare other metal oxides, or to prepare other metal selenides, metal carbides, metal nitrides, etc.

[0109] In a specific embodiment, step S10, passing the gaseous delithiation agent into the porous carrier so that the gaseous delithiation agent is contained in the pores of the porous carrier, comprises:

[0110] Step S11, placing the porous carrier loaded with the catalyst obtained in step S00 in a reactor, introducing a gaseous delithiation agent precursor into the reactor, and obtaining a porous carrier loaded with the gaseous delithiation agent and the catalyst after sufficient reaction.

[0111] Optionally, in step S11, the gaseous delithiation agent precursors are NO gas and O2 gas, and the reaction kettle may be a tubular furnace; the ratio of NO gas to O2 may be 2:1, and the ventilation time may be 2h to 6h.

[0112] It should be explained that the gaseous delithiation agent prepared in the above steps is NO2, but the above steps can also be used to prepare any other feasible gaseous delithiation agent, such as SO2.

[0113] In a specific embodiment, reference Figure 8 , step S20, combining the lithium-rich material with a porous carrier loaded with a gaseous delithiation agent, further comprising:

[0114] Step S21, mixing a non-lithium metal element precursor with a lithium-rich material precursor and then ball milling them to obtain a lithium-rich material doped with the non-lithium metal element.

[0115] Step S22, adding the porous carrier loaded with the gaseous delithiation agent and the catalyst into the dispersant to obtain a dispersion A.

[0116] Step S23, dissolving the lithium-rich material doped with non-lithium metal elements in solvent B, and adding dispersion A thereto at a uniform speed to obtain a lithium-supplementing material.

[0117] Optionally, in step S21, the non-lithium metal element precursor is K2O, and the lithium-rich material precursor is Li2C2O4 (lithium oxalate); the K / Li atomic ratio can be (1-10):100, the bead-to-material ratio in the ball milling process can be (10-20):1, the large bead:small bead mass ratio is (6-12):1, and the ball milling time can be 12h-36h.

[0118] Optionally, in step S22, the dispersant may be alcohol.

[0119] Optionally, in step S23, solvent B may be deionized water; and the flow rate of uniformly adding dispersion A may be 1 mL / min.

[0120] It should be explained that the lithium-rich material prepared in the above steps is lithium oxalate doped with potassium atoms, but the above steps can also be used to prepare any other feasible lithium-rich material doped with non-lithium metal elements, such as lithium oxalate doped with sodium atoms, lithium oxalate doped with aluminum atoms, etc.

[0121] The present invention prepares a porous carrier with pores to load a gaseous delithiation agent, and then combines a lithium-rich material on the porous carrier. The gaseous delithiation agent contained in the pores reacts with the lithium-rich material to promote the decomposition of the lithium-rich material, accelerate the release rate of lithium ions, and improve the release efficiency of lithium ions. The gaseous delithiation agent after the reaction is reduced to anions in the electrolyte, which can accelerate the transmission of lithium ions and improve the power of lithium ion transmission. Moreover, the porous carrier itself can improve the overall conductivity of the lithium-supplementing material, and at the same time can provide space for the flow and reaction of the gaseous delithiation agent, and after the lithium-rich material produces gas, it ensures the orderly flow of gas, and the gas that cannot be discharged during battery formation can be adsorbed in the porous carrier, which will not cause battery bulging, and can protect the stability of the material and the safety of the battery.

[0122] Furthermore, in the present invention, a catalyst is loaded on the carrier during the process of preparing the porous carrier, and the catalyst can expose more active sites, which can further reduce the delithiation potential of the lithium-rich material.

[0123] Furthermore, in the process of preparing lithium-rich materials, the present invention dopes non-lithium metal element atoms into Li positions, which can cause lattice defects in lithium-rich materials, increase the vacancy concentration of Li, and improve the conductivity of lithium-rich materials. At the same time, it can expand the interlayer spacing of the crystal structure of lithium-rich materials, reduce the intermolecular force, expand the lithium ion transmission channel, and reduce the polarization voltage required for the decomposition of lithium-rich materials. In addition, the non-lithium metal ions released after lithium-rich materials are de-lithiated are combined with anions formed by the reduction of gaseous de-lithiation agents, which can be used as electrolyte additives to accelerate the transmission of lithium ions and improve the power of lithium ion transmission.

[0124] In one embodiment, the present invention further provides a positive electrode material, the positive electrode material includes a positive electrode active material and a lithium supplement material. The lithium supplement material is the lithium supplement material provided in the above embodiment. Optionally, the positive electrode active material can be a phosphate positive electrode active material and a ternary positive electrode active material, and in a specific embodiment, includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium vanadium phosphate fluoride, lithium titanate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

[0125] In one embodiment, the content of lithium-supplementing material in the positive electrode material can be controlled at 1% to 6% of the mass of the positive electrode active material. This ratio can just make up for the loss of active lithium in the battery during the first charging process. If the amount of lithium-supplementing material added to the positive electrode material is too low, the active lithium lost in the positive electrode active material cannot be fully replenished, which is not conducive to improving the energy density and capacity retention rate of the battery. If the amount of lithium-supplementing material added to the positive electrode active material is too high, the original reversible capacity will be occupied and the cost will be increased. In some specific embodiments, in the positive electrode material, the mass percentage of the lithium-supplementing material can be 1%, 2%, 4%, 6%, etc.

[0126] In one embodiment, the present invention further provides a positive electrode plate, the positive electrode plate includes a current collector and an active material layer disposed on the current collector, the active material layer includes the lithium supplement material of any one of the above embodiments. Or the active material layer includes the lithium supplement material obtained by the preparation method of the lithium supplement material in the above embodiments.

[0127] In one embodiment, the positive electrode sheet includes a positive electrode current collector, and the positive electrode current collector has a positive electrode active layer, and the positive electrode active layer includes components such as positive electrode active materials, lithium supplement materials, conductive agents, and binders. The present invention does not specifically limit these materials, and suitable materials can be selected according to actual application requirements. The positive electrode current collector includes but is not limited to any one of copper foil and aluminum foil. The conductive agent includes one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60 and carbon nanotubes, and the content of the conductive agent in the positive electrode active layer is 3wt% to 5wt%. The types of binders include polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan and chitosan derivatives, and the content of the binder in the positive electrode active layer is 2wt% to 4wt%.

[0128] In one embodiment, the present invention further provides a secondary battery, the secondary battery comprising a positive electrode, a negative electrode and an electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode comprises the positive electrode material described above.

[0129] The electrolyte conducts electricity by facilitating the movement of ions. During charging, ions move from the positive electrode to the negative electrode; during discharging, ions move in the opposite direction. The electrolyte ensures the closure of the internal circuit of the secondary battery, allowing electrons to flow from one electrode to another through an external circuit, thereby forming an electric current. Optionally, the electrolyte includes at least one of a molten salt electrolyte, a solid electrolyte, and a liquid electrolyte. In a specific embodiment, the electrolyte is an inorganic liquid electrolyte or an organic liquid electrolyte. In other embodiments, the electrolyte may also be an inorganic solid electrolyte, a pure solid polymer electrolyte (DSPE), a gel polymer electrolyte (GSPE), a porous polymer electrolyte (PSPE), a composite polymer electrolyte (CSPE), and the like.

[0130] The technical solution of the present invention is described in detail below through specific embodiments.

[0131] Example 1

[0132] This embodiment provides a lithium supplement material, which includes a porous carrier (porous carbon carrier), a gaseous lithium removal agent (NO2), a lithium-rich material (lithium oxalate), and a catalyst (cobalt oxide). The porous carrier includes holes, NO2 is contained in the first hole, cobalt oxide is contained in the hole, and lithium oxalate blocks the opening of the hole; the lithium oxalate is also doped with K atoms.

[0133] The mass ratio of lithium oxalate, porous carbon and catalyst is 100:20:5; the particle size of porous carbon is 5um; the specific surface area of ​​porous carbon is 600m 2 / g; the coating thickness of the lithium-rich material is 2um; the particle size of cobalt oxide is 10nm.

[0134] The preparation method of the lithium supplement material comprises the following steps:

[0135] 1) 5 g of activated carbon was added to 50 mL of an aqueous solution of 2M nitric acid, and the mixture was shaken and impregnated at room temperature for 48 h. After the impregnation, the activated carbon was filtered out, washed with deionized water for multiple times, dried in air at 120° C., and then calcined in air at 400° C. for 4 h; 40 g of cobalt acetate hexahydrate was dissolved in 100 mL of deionized water to prepare a solution, and the activated carbon was added at room temperature, and the activated carbon was impregnated for 4 h, and then dried at 120° C.; 12 g of potassium hydroxide was dissolved in 120 mL of deionized water, and the activated carbon was added at room temperature, and then the activated carbon was impregnated for 4 h, and then dried at 120° C., and then calcined in nitrogen at 300° C. for 4 h to obtain a porous carrier loaded with a catalyst.

[0136] 2) The porous carrier loaded with catalyst obtained in 1) is placed in a tubular furnace, and gas is introduced into the tubular furnace at a NO gas flow rate of 100 ppm and an air gas flow rate of 250 ppm. NO is oxidized in the tubular furnace to generate NO2, which is adsorbed on the activated carbon material to obtain a porous carrier loaded with NO2 and catalyst.

[0137] 3) Mix K2O and lithium oxalate according to the atomic ratio of K:Li = 0.05:1.95, place them in a ball mill and perform high-speed ball milling to dope K atoms into the Li position. The bead-to-material ratio during the ball milling process is 10-20:1; the mass ratio of large beads: small beads is 6-12:1, and the ball milling time is 12 hours.

[0138] 4) The porous carrier loaded with NO2 and the catalyst obtained in 2) is placed in alcohol and dispersed evenly, the lithium oxalate doped with K atoms obtained in 3) is dissolved in deionized water, and the dispersion containing the porous carrier loaded with NO2 and the catalyst is added at a uniform speed to make the K-doped lithium oxalate evenly coated on the surface of the porous carrier.

[0139] Example 2

[0140] This embodiment provides a lithium supplement material. The material structure of this embodiment is basically the same as that of embodiment 1. The difference between the two is that there is no catalyst in the lithium supplement material of this embodiment, and the lithium-rich material is not doped with non-lithium metal elements. The difference in steps is that in the preparation method of the lithium supplement material, the transition metal salt impregnation of step 1) and step 3) are eliminated to obtain a porous carbon carrier loaded with NO2 and lithium oxalate.

[0141] Example 3

[0142] This embodiment provides a lithium-supplementing material. The material structure of this embodiment is basically the same as that of embodiment 1, and the difference between the two is that the lithium-rich material of this embodiment is not doped with non-lithium metal elements. The difference in steps is that step 3) is eliminated in the preparation method of the lithium-supplementing material to obtain a porous carbon carrier loaded with NO2, cobalt oxide and lithium oxalate.

[0143] Example 4

[0144] This embodiment provides a lithium supplement material. The material structure of this embodiment is basically the same as that of embodiment 1. The difference between the two is that there is no catalyst in the lithium supplement material of this embodiment. The difference in steps is that in the preparation method of the lithium supplement material, the transition metal salt impregnation in step 1) is eliminated to obtain a porous carbon carrier loaded with NO2 and lithium oxalate doped with K atoms.

[0145] Example 5

[0146] This embodiment provides a lithium supplement material. The material structure of this embodiment is basically the same as that of embodiment 1. The difference between the two is that in this embodiment, the gaseous delithiation agent is SO2, and SO2 is introduced in step 2) to obtain a porous carbon carrier loaded with SO2.

[0147] Example 6

[0148] This embodiment provides a lithium supplement material. The material structure of this embodiment is basically the same as that of Example 1. The difference between the two is that in this embodiment, the ratio of the volume of NO2 to the pore area of ​​the porous carrier is 0.2. The difference in the steps is that the NO gas flow rate introduced is 50ppm, and the air gas flow rate introduced is 125ppm.

[0149] Example 7

[0150] This embodiment provides a lithium supplement material. The material structure of this embodiment is basically the same as that of Example 1. The difference between the two is that in this embodiment, the ratio of the volume of NO2 to the pore volume of the porous carrier is 0.8. The difference in the steps is that the NO gas flow rate introduced is 200ppm, and the air gas flow rate introduced is 500ppm.

[0151] Example 8

[0152] This embodiment provides a lithium supplement material. The material structure of this embodiment is basically the same as that of embodiment 1. The difference between the two is that in this embodiment, the doped non-lithium metal element is Na, and the loaded catalyst is NiO. The difference in the steps is that in step 3), NaOH and lithium oxalate are mixed according to the Na:Li atomic ratio of 0.05:1.95.

[0153] Comparative Example 1

[0154] This comparative example provides a lithium supplement material (lithium oxalate).

[0155] Comparative Example 2

[0156] This comparative example provides a lithium supplement material, including lithium oxalate and porous carbon, which are simply mixed.

[0157] Comparative Example 3

[0158] This comparative example provides a lithium supplement material, including lithium oxalate, porous carbon and cobalt oxide, which are simply mixed.

[0159] The lithium supplement materials provided in the above-mentioned Examples 1 to 8 and the lithium supplement materials provided in Comparative Examples 1 to 3 are respectively assembled into positive electrode sheets and lithium-ion batteries according to the following methods:

[0160] Positive electrode sheet: The lithium supplement material, SP and PVDF are mixed in a mass ratio of 90:4:6 to prepare a positive electrode slurry, the positive electrode slurry is coated on the surface of aluminum foil, vacuum dried at 110°C overnight, and rolled to obtain a positive electrode sheet;

[0161] Negative electrode: lithium sheet;

[0162] Electrolyte: Ethylene carbonate and ethyl methyl carbonate were mixed in a volume ratio of 3:7, and LiPF6 was added to form an electrolyte, and the concentration of LiPF6 was 1 mol / L;

[0163] Diaphragm: Polypropylene microporous separator;

[0164] Lithium-ion battery assembly: Assemble button-type lithium-ion full batteries in an inert atmosphere glove box in the order of negative electrode sheet - separator - electrolyte - positive electrode sheet.

[0165] The electrochemical performance of each lithium-ion battery assembled in the above lithium-ion battery embodiment was tested under the following test conditions:

[0166] The battery was charged at a rate of 0.1C with a cut-off voltage of 4.7V. The battery was charged at a constant voltage of 4.7V. After the charging process was completed, the battery was allowed to stand for 10 minutes and then discharged at a rate of 0.1C with a cut-off voltage of 2.5V. The charging platform was observed during the charging process to obtain the delithiation potential of the lithium supplement material.

[0167] Resistivity test: The resistivity of the positive electrode lithium supplement material in each embodiment and comparative example was calculated and tested by a four-probe method.

[0168] The test results of the above lithium supplement materials and lithium batteries are shown in Table 1 below:

[0169] Table 1. Test results of embodiments and comparative examples

[0170]

[0171] From the comparison between Example 1 and Comparative Example 1 in Table 1, it can be seen that the resistivity and delithiation voltage of the lithium supplement material in Example 1 are lower than those of the lithium supplement material in Comparative Example 1, and the initial charging capacity and the delithiation voltage below 4.2V are higher than those of Comparative Example 1. The reason is that Comparative Example 1 only includes lithium-rich materials, while the lithium supplement material in Example 1 includes a porous carrier and a gaseous delithiation agent loaded thereon. On the one hand, the porous carrier improves the conductivity of the lithium supplement material and can reduce the delithiation potential of the lithium supplement material to a certain extent. On the other hand, the lithium supplement material in Example 1 contains a catalyst and NO2, the latter of which can assist in delithiation, and the former further reduces the delithiation potential of the lithium supplement material, prolongs the delithiation platform, and improves the delithiation capacity under low-pressure conditions. Please also refer to Fig. 9 , Fig. 9 The scanning electron microscope image of Example 1 shows the lithium supplement agent grown in situ in the carbon pores; NO2 is adsorbed in the carbon pores, and there is a certain amount of K + Doping.

[0172] From the comparison between Example 1 and Comparative Examples 2 and 3 in Table 1, it can be seen that the lithium supplement materials simply mixed in Comparative Examples 2 and 3 have no advantages. The reason is that simple mixing may not be uniform, and the poor contact between the materials makes it impossible to remove lithium at low pressure.

[0173] From the comparison between Example 1 and Example 2 and Example 3 in Table 1, it can be seen that the composite lithium supplement material in Example 1 has more advantages. The reason is that the lithium supplement material in Example 1 is doped with K + , which can react with NO2 to generate NO2 - Combined with the generated KNO2, it accelerates the transmission of lithium ions and improves the lithium replenishment effect of the lithium replenishment material.

[0174] From the comparison between Example 1 and Example 2 and Example 4 in Table 1, it can be seen that the lithium supplement material in Example 1 has a greater lithium supplement advantage. The reason is that the lithium supplement materials in Example 2 and Example 4 do not contain a catalyst, which can reduce the decomposition platform voltage of the material, while the main function of the gaseous delithiation agent is to assist the release of lithium ions, and its effect of reducing the decomposition voltage of the lithium supplement material is not sufficient.

[0175] From the comparison between Example 1 and Example 5 in Table 1, it can be seen that the lithium supplement material in Example 1 has more catalytic advantages. The reason is that although the catalyst in Example 5 can significantly reduce the decomposition voltage of lithium oxalate, the catalyst has limited improvement on the lithium ion removal efficiency, and the effect of SO2 on the reaction with lithium oxalate to assist lithium removal is inferior to that of NO2 in Example 1. Therefore, the lithium supplement effect of Example 5 is not as good as that of Example 1.

[0176] From the comparison between Example 1 and Example 6 and Example 7 in Table 1, it can be seen that the lithium supplementation effect of Example 6 and Example 7 at low voltage is not as good as that of Example 1. The reason is that the NO2 adsorbed in the porous carrier has a better catalytic effect only when the reserve is appropriate. The content of NO2 in Example 6 is too low, and the effect of NO2 assisting the lithium supplementation material in delithiation is not obvious. The content of NO2 in Example 7 is too high, occupying too much pore volume of the porous carrier, which may affect the volume change of the lithium supplementation material during the delithiation process, and the excess NO2 cannot be used, but will affect the overall delithiation of the lithium supplementation material.

[0177] From the comparison between Example 1 and Example 8 in Table 1, it can be seen that the catalytic material used in Example 1 has a more obvious advantage. The reason is that although NiO used as a catalyst in Example 8 has a certain catalytic effect, the catalytic effect is not as good as CoO. In addition, the radius of the Na ion doped in Example 8 is smaller than the radius of the K ion doped in Example 1. After Na ions are doped with lithium oxalate, the interlayer spacing is small, and the effect of generating lattice defects to increase the Li vacancy concentration is not as good as that of K ions doped with lithium oxalate.

[0178] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0179] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A lithium supplement material, characterized in that: The invention comprises a porous carrier, a gaseous lithium removal agent and a lithium-rich material. The porous carrier has pores, the gaseous lithium removal agent is adsorbed and contained in the pores, and the lithium-rich material is combined with the porous carrier.

2. The lithium supplement material according to claim 1, characterized in that: The gaseous delithiation agent includes at least one of NO2 and SO2.

3. The lithium supplement material according to claim 1, characterized in that: The porous carrier comprises at least one of a carbon material, an organic polymer material, and a metal compound; and / or The specific surface area of ​​the porous carrier is 200 m 2 / g~800m 2 / g; and / or The pore volume of the porous carrier is 1.35 cm 3 / g~2.10cm 3 / g; and / or The ratio of the volume of the gaseous delithiation agent to the pore area of ​​the porous carrier is 0.5 to 1; and / or The D50 particle size of the porous carrier is 1 um to 5 um.

4. The lithium supplement material according to claim 1, characterized in that: The D50 particle size of the lithium-rich material is 500 nm to 1 um, and / or the lithium-rich material surrounds and wraps around the surface of the porous carrier or the lithium-rich material blocks the pores.

5. The lithium supplement material according to any one of claims 1 to 4, characterized in that: The lithium-rich material is doped with non-lithium metal elements, The non-lithium metal element includes at least one of Na and K; and / or The molar ratio of the non-lithium metal element to Li contained in the lithium-rich material is x:(1-x), wherein 0<x<0.

5.

6. The lithium supplement material according to claim 1, characterized in that: The lithium-supplementing material further includes a catalyst, and at least a portion of the lithium-rich material is connected to the catalyst.

7. The lithium supplement material according to claim 6, characterized in that: The catalyst comprises at least one of metal selenide, metal oxide, metal carbide and metal nitride; and / or The D50 particle size of the catalyst is 2nm to 20nm; and / or The mass ratio of the lithium-rich material, the porous carrier and the catalyst is 100:(25-100):(5-20).

8. A method for preparing a lithium supplement material, characterized in that: include: Passing a gaseous delithiation agent into a porous carrier so that the gaseous delithiation agent is adsorbed and contained in the pores of the porous carrier; The lithium-rich material is combined with the porous carrier loaded with the gaseous delithiation agent to obtain a lithium-supplementing material.

9. The method for preparing the lithium supplement material according to claim 8, characterized in that: The invention also includes: loading the catalyst on a porous carrier; and / or The lithium-rich material is combined with the porous carrier loaded with the gaseous delithiation agent, and further includes: the lithium-rich material is doped with non-lithium metal elements.

10. A secondary battery, characterized in that: It comprises a positive electrode, a negative electrode and an electrolyte arranged between the positive electrode and the negative electrode, wherein the positive electrode comprises the lithium supplement material according to any one of claims 1 to 7, or comprises the lithium supplement material obtained by the preparation method of the lithium supplement material according to claim 8 or 9.

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