Modified lithium-rich manganese-based spherical aggregate and preparation method thereof, lithium-rich manganese-based electrode and preparation method and application thereof

Abstract

The invention provides a modified lithium-rich manganese-based spherical aggregate and a preparation method thereof, a lithium-rich manganese-based electrode and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. According to the preparation method of the modified lithium-rich manganese-based spherical aggregate, the conductive particles and the lithium-rich manganese-based spherical aggregate are mixed, and pores of the lithium-rich manganese-based spherical aggregate are filled with the conductive particles by limiting the particle size of the conductive particles, so that the particles of the lithium-rich manganese-based spherical aggregate are more compact; in the rolling process of preparing the electrode by using the spherical aggregate, the lithium-rich manganese-based spherical aggregate particles are uniformly stressed, and the conductive particles also play a supporting role, so that the integrity of the particles is kept, and the condition that the cycling stability of the electrode is influenced due to particle breakage is avoided; meanwhile, the compact lithium-rich manganese-based spherical aggregate also reduces the porosity of the electrode, reduces the contact interface between the electrode and the electrolyte, and reduces the side reaction, thereby improving the cycling stability of the electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a modified lithium-rich manganese-based spherical agglomerate and a preparation method thereof, a lithium-rich manganese-based electrode and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy electric vehicles, electric aircraft and other industries, the requirements for the cycle life of commercial lithium-ion batteries are getting higher and higher. One of the main factors affecting the cycle life of batteries is the positive electrode material of the battery. As a positive electrode material, lithium-rich manganese-based laminated oxides have an ultra-high specific capacity (>280mAh / g) and are considered to be ideal materials for building high-energy lithium-ion batteries. However, although lithium-rich manganese-based positive electrode materials have high specific capacity, the cycle stability of the electrodes they manufacture is poor and cannot meet the cycle life requirements of commercial lithium-ion batteries.

[0003] The main reason for the poor cycle stability of lithium-rich manganese-based electrodes is that the electrode obtained after the lithium-rich manganese-based spherical agglomerates are coated has a large porosity, a large contact interface with the electrolyte, and serious side reactions; the particle structure of the lithium-rich manganese-based spherical agglomerates is loose, and the particles are severely broken after rolling, exposing new interfaces for more side reactions. At present, the research on lithium-rich manganese-based spherical agglomerates mainly focuses on modifying lithium-rich manganese-based spherical agglomerates to improve the density of the material and thus improve the cycle stability of the electrode. Common modification methods include atomic deposition technology, lithium iron phosphate coating technology, and dynamic sintering technology. Although these methods also improve the density of lithium-rich manganese-based spherical agglomerates and thus improve the cycle life of the electrode, these methods are relatively complex and have high operating requirements. They require accurate control of the type, amount, and modification process of raw materials, otherwise the modification effect will be greatly reduced. Summary of the invention

[0004] The purpose of the present invention is to provide a modified lithium-rich manganese-based spherical agglomerate and a preparation method thereof, a lithium-rich manganese-based electrode and a preparation method and application thereof. The preparation method of the modified lithium-rich manganese-based spherical agglomerate provided by the present invention is simple and easy to implement, has a wide range of raw material adjustment, good modification effect, and is conducive to industrialization.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing modified lithium-rich manganese-based spherical agglomerates, comprising: mixing the lithium-rich manganese-based spherical agglomerates with a densification auxiliary material to obtain modified lithium-rich manganese-based spherical agglomerates; the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates is 1:(8-25); the densification auxiliary material is conductive particles with a particle size of 1-500 nm.

[0007] Preferably, the densification auxiliary material includes one or more of a lithium-containing material and a carbon material, and the lithium-containing material includes one or more of an oxide solid electrolyte material, a sulfide solid electrolyte material, and a halide solid electrolyte material.

[0008] Preferably, the mixing comprises dry-mixing the lithium-rich manganese-based spherical agglomerates with the densification auxiliary material or wet-mixing the lithium-rich manganese-based spherical agglomerates with the densification auxiliary material in a solvent.

[0009] Preferably, the densification auxiliary material and the lithium-rich manganese-based spherical agglomerates are mixed and then sintered.

[0010] Preferably, the sintering temperature is 600-800°C.

[0011] The present invention also provides a modified lithium-rich manganese-based spherical aggregate prepared by the preparation method described in the above technical solution, wherein the tap density of the modified lithium-rich manganese-based spherical aggregate is 1.5 to 3.5 g / cm 3 .

[0012] The present invention also provides a method for preparing a lithium-rich manganese-based electrode, comprising: mixing a conductive agent, a binder, a modified lithium-rich manganese-based spherical aggregate and a solvent to prepare a slurry, coating the slurry on a current collector, and then drying and rolling the slurry in sequence to obtain a lithium-rich manganese-based electrode, wherein the modified lithium-rich manganese-based spherical aggregate is the modified lithium-rich manganese-based spherical aggregate described in the above technical solution, and the compaction density of the rolling is 1.8 to 3.3 g / cm 3 .

[0013] Preferably, a densification auxiliary material is also added during the mixed slurrying, and the densification auxiliary material is conductive particles with a particle size of 1 to 500 nm; the mass ratio of the densification auxiliary material to the modified lithium-rich manganese-based spherical agglomerates is 1:(5 to 10).

[0014] The present invention also provides a lithium-rich manganese-based electrode prepared by the preparation method described in the above technical solution.

[0015] The present invention also provides the application of the lithium-rich manganese-based electrode described in the above technical solution in a lithium-containing energy storage device.

[0016] The present invention provides a method for preparing modified lithium-rich manganese-based spherical agglomerates, comprising: mixing the lithium-rich manganese-based spherical agglomerates with a densification auxiliary material to obtain modified lithium-rich manganese-based spherical agglomerates; the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates is 1:(8-25); the densification auxiliary material is conductive particles with a particle size of 1-500 nm. The present invention mixes conductive particles with lithium-rich manganese-based spherical agglomerates, and controls the particle size of the conductive particles so that the conductive particles are filled into the pores of the lithium-rich manganese-based spherical agglomerates, thereby making the particles of the lithium-rich manganese-based spherical agglomerates more compact. In the rolling process of preparing electrodes using the lithium-rich manganese-based spherical agglomerates, the filled conductive particles can make the spherical agglomerate particles evenly stressed, and the conductive particles also play a supporting and protective role, which can maintain the integrity of the spherical agglomerate particles while increasing the compaction density, thereby avoiding the spherical agglomerate particles from breaking and affecting the cycle stability of the electrode. At the same time, the dense lithium-rich manganese-based spherical agglomerates also reduce the porosity of the electrode, reduce the contact interface between the electrode and the electrolyte, reduce side reactions, and thus improve the cycle stability of the electrode. The results of the embodiment show that the modified lithium-rich manganese-based spherical aggregates obtained by the preparation method provided by the present invention are used to make electrodes and assembled into soft-pack batteries. After 200 charge and discharge cycle tests at a current density of 200 mA / g in the voltage range of 2.0 to 4.5 V, the capacity retention rate is above 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a SEM image of the lithium-rich manganese-based electrode prepared in Example 9;

[0018] Figure 2 This is a SEM image of the lithium-rich manganese-based electrode prepared in Comparative Example 4;

[0019] Figure 3 This is a SEM image of the lithium-rich manganese-based electrode prepared in Example 12;

[0020] Figure 4 This is a SEM image of the lithium-rich manganese-based electrode prepared in Example 13;

[0021] Figure 5 This is a SEM image of the lithium-rich manganese-based electrode prepared in Comparative Example 1;

[0022] Figure 6 This is the SEM image of the lithium-rich manganese-based electrode prepared in Comparative Example 6. DETAILED DESCRIPTION

[0023] All raw materials of the present invention have no particular limitation on their sources and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0024] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses high-purity or conventional purity in the field of lithium-ion batteries.

[0025] The present invention provides a method for preparing modified lithium-rich manganese-based spherical agglomerates, comprising: mixing the lithium-rich manganese-based spherical agglomerates with a densification auxiliary material to obtain modified lithium-rich manganese-based spherical agglomerates; the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates is 1:(8-25); the densification auxiliary material is conductive particles with a particle size of 1-500 nm.

[0026] The invention mixes lithium-rich manganese-based spherical aggregates with a densification auxiliary material to obtain modified lithium-rich manganese-based spherical aggregates.

[0027] In the present invention, the lithium-rich manganese-based spherical aggregates are preferably composite spherical aggregates based on LiMnO. As an embodiment of the present invention, the lithium-rich manganese-based spherical aggregates can be xLi 2 MnO 3 (1-x)LiCoO 2 、xLi 2 MnO 3 ·(1-x)LiNi a Co 1-a O 2 、xLi 2 MnO 3 ·(1-x)LiNi b Mn 1-b O 2 or xLi 2 MnO 3 ·(1-x)LiNi a Co b Mn (1-a-b) O 2 In an embodiment of the present invention, the lithium-rich manganese-based spherical aggregates are xLi 2 MnO 3 ·(1-x)LiNi a Co b Mn (1-a-b) O 2 .

[0028] In the present invention, the densification auxiliary material is a conductive particle, preferably including one or more of a lithium-containing material and a carbon material. The lithium-containing material preferably includes one or more of an oxide solid electrolyte material, a sulfide solid electrolyte material, and a halide solid electrolyte material. As one embodiment of the present invention, the oxide solid electrolyte material can be lithium carbonate, or lithium oxide, lithium hydroxide, lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickel manganate, lithium nickel cobalt manganate, lithium nickel cobalt aluminum oxide, or lithium lanthanum zirconium tantalum oxide; the sulfide solid electrolyte material can be lithium phosphorus sulfur chlorine, or lithium germanium phosphorus sulfur, lithium phosphorus sulfur, or lithium sulfide; the halide solid electrolyte material can be lithium indium chloride, or lithium aluminum fluoride, lithium arsenic chloride, or lithium titanium chloride. As another embodiment of the present invention, the carbon material can be a 0-dimensional carbon sphere or a graphite sphere.

[0029] In the present invention, the particle size of the conductive particles is 1 to 500 nm, preferably 100 to 400 nm, and more preferably 200 to 300 nm. As an embodiment of the present invention, the particle size of the conductive particles may be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm or 450 nm. The particle size of the conductive particles within the above range can be filled into the pores of the lithium-rich manganese-based spherical agglomerates to increase the tap density of the spherical agglomerates.

[0030] In the present invention, the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates is 1: (8-25), preferably 1: (10-20), and more preferably 1: (12-16). When modifying the lithium-rich manganese-based spherical agglomerates, the amount of the densification auxiliary material directly affects the modification effect. If the amount is too little, the pores of the lithium-rich manganese-based spherical agglomerates cannot be completely filled, and the modification effect is poor; if the amount is too much, too much densification auxiliary material will be accumulated on the surface of the lithium-rich manganese-based spherical agglomerates, affecting the entry and exit of lithium ions into the positive electrode material. As an embodiment of the present invention, the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates can be 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24 or 1:25.

[0031] In the present invention, the mixing preferably includes dry mixing the lithium-rich manganese-based spherical agglomerates with the densification auxiliary material or wet mixing the lithium-rich manganese-based spherical agglomerates with the densification auxiliary material in a solvent. During the mixing process, the densification auxiliary material will fill the pores of the lithium-rich manganese-based spherical agglomerates, and wet mixing can make the densification auxiliary material more evenly dispersed and have a better filling effect.

[0032] In the present invention, the wet mixing solvent is preferably N-methylpyrrolidone, dimethyl carbonate, ethylene carbonate or diethylene carbonate. The amount of the solvent is preferably sufficient to immerse the solid material.

[0033] In the present invention, the mixing speed is preferably 500-3000rpm, more preferably 1000-2000rpm. The mixing time is preferably 0.1-4h, more preferably 1-3h. In an embodiment of the present invention, the mixing speed is 1000rpm. The mixing speed affects the filling effect of the densification auxiliary material. If the speed is too slow, the filling time is too long, which affects the efficiency and the filling is uneven; if the speed is too fast, the lithium-rich manganese-based spherical agglomerates are subjected to excessive force and there is a risk of rupture.

[0034] In the present invention, the mixing time is preferably 0.1 to 4 hours, more preferably 1 to 3 hours. In an embodiment of the present invention, the mixing time is 2 hours. The mixing time affects the filling effect of the densification auxiliary material. If the time is too short, the filling is incomplete, and if the time is too long, the lithium-rich manganese-based spherical agglomerate particles may be broken. Limiting the mixing parameters within the above range is conducive to the effective filling of the densification auxiliary material and can prevent the lithium-rich manganese-based spherical agglomerate particles from breaking.

[0035] The present invention has no special requirements for the mixing device, as long as the lithium-rich manganese-based spherical aggregates and the densification auxiliary material can be fully contacted. In the embodiment of the present invention, the mixing device used is a high-speed mixer.

[0036] In the present invention, the densification auxiliary material and the lithium-rich manganese-based spherical agglomerates are preferably mixed and then sintered. Sintering can improve the crystallinity of the lithium-rich manganese-based spherical agglomerates and the densification auxiliary material, making the modified lithium-rich manganese-based spherical agglomerates denser and more regular in structure, which is beneficial to improving the electrochemical performance of the electrode.

[0037] In the present invention, the sintering temperature is preferably 600-800°C, more preferably 650-750°C. In an embodiment of the present invention, the sintering temperature is 650°C, 700°C or 750°C. The sintering temperature affects the density of the lithium-rich manganese-based spherical agglomerates. If the sintering temperature is too low, the density improvement effect is not obvious; if the sintering temperature is too high, lithium will volatilize and reduce the energy density of the material. The sintering temperature within the above range is conducive to further improving the density of the lithium-rich manganese-based spherical agglomerates.

[0038] In the present invention, the sintering holding time is preferably 10 to 20 hours, more preferably 12 to 16 hours. In an embodiment of the present invention, the sintering holding time can be 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours. The sintering holding time affects the density of the lithium-rich manganese-based spherical agglomerates. If the holding time is too short, the density improvement effect is not obvious; if the holding time is too long, lithium will volatilize and reduce the energy density of the material. The sintering holding time within the above range is conducive to further improving the density of the lithium-rich manganese-based spherical agglomerates.

[0039] The present invention mixes conductive particles with lithium-rich manganese-based spherical agglomerates, and controls the particle size of the conductive particles so that the conductive particles are filled into the pores of the lithium-rich manganese-based spherical agglomerates, thereby making the particles of the lithium-rich manganese-based spherical agglomerates more compact. In the rolling process of preparing electrodes using the lithium-rich manganese-based spherical agglomerates, the spherical agglomerate particles are subjected to uniform force, and the conductive particles also play a supporting role, thereby maintaining the integrity of the spherical agglomerate particles, thereby avoiding the breakage of the spherical agglomerate particles and affecting the cycle stability of the electrode; at the same time, the dense lithium-rich manganese-based spherical agglomerates also reduce the porosity of the electrode, reduce the contact interface between the electrode and the electrolyte, reduce side reactions, and thus improve the cycle stability of the electrode.

[0040] The present invention also provides modified lithium-rich manganese-based spherical aggregates prepared by the preparation method described in the above technical solution.

[0041] In the present invention, the tap density of the modified lithium-rich manganese-based spherical aggregates is 1.5 to 3.5 g / cm 3 , preferably 1.8 to 3.3 g / cm 3 , more preferably 2.4 to 3.1 g / cm 3 . The tap density affects the compaction density of the electrode, and further affects the cycle stability of the electrode. The present invention fills the lithium-rich manganese-based spherical agglomerates with conductive particles so that the tap density of the modified lithium-rich manganese-based spherical agglomerates is within the above range, which is beneficial to reducing the porosity of the spherical agglomerates; when making the electrode, the breakage of the spherical agglomerate particles is reduced, and the side reaction between the electrode and the electrolyte is reduced, thereby improving the cycle stability of the electrode.

[0042] The present invention also provides a method for preparing a lithium-rich manganese-based electrode, comprising: mixing a conductive agent, a binder, modified lithium-rich manganese-based spherical aggregates and a solvent to prepare a slurry, coating the slurry on a current collector, and then drying and rolling the slurry in sequence to obtain a lithium-rich manganese-based electrode.

[0043] In the present invention, the modified lithium-rich manganese-based spherical aggregates are the modified lithium-rich manganese-based spherical aggregates described in the above technical solution.

[0044] In the present invention, the compaction density of the roller is 1.8 to 3.3 g / cm 3, preferably 2.4 to 3.1 g / cm 3 The higher the compaction density, the greater the specific capacity of the electrode and the better the cycle stability. However, when the compaction density exceeds 3.3 g / cm 3 After that, too high a compaction density will cause the lithium-rich manganese-based spherical agglomerate particles to break, thereby reducing the cycle stability of the electrode. The compaction density within the above range has good specific capacity and cycle stability. As an embodiment of the present invention, the compaction density can be 1.8g / cm 3 , 1.9g / cm 3 , 2.0g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 , 2.3g / cm 3 , 2.4g / cm 3 , 2.5g / cm 3 , 2.6g / cm 3 , 2.7g / cm 3 , 2.8g / cm 3 , 2.9g / cm 3 , 3.0g / cm 3 , 3.1g / cm 3 , 3.2g / cm 3 or 3.3g / cm 3 .

[0045] The present invention has no special limitation on the specific parameters of the rolling, and rolling to the desired compaction density can be adopted in a manner well known to those skilled in the art.

[0046] The present invention has no special requirements on the types and amounts of the conductive agent, binder and solvent, and the types and amounts commonly used in the art can be used. In an embodiment of the present invention, the conductive agent is conductive carbon black, the binder is polyvinylidene fluoride, the solvent is N-methylpyrrolidone, and the solid content of the slurry is 50%.

[0047] In the present invention, a densification auxiliary material is preferably added during the mixed pulping, and the densification auxiliary material is a conductive particle with a particle size of 1 to 500 nm. The densification auxiliary material is added during the pulping process of the present invention, so that it can be attached to the surface of the spherical agglomerate, which can reduce the pores of the spherical agglomerate itself, and can also be used as a filler between the spherical agglomerate particles. When the slurry is coated, the density of the coating can be improved, and the spherical agglomerate particles can be evenly stressed during the rolling process, reducing the rupture of the spherical agglomerate particles during the rolling process, thereby further improving the cycle stability of the electrode.

[0048] In the present invention, the type of the densification auxiliary material used in the mixed pulping is preferably the same as the densification auxiliary material used in the preparation of the modified lithium-rich manganese-based spherical agglomerates described in the above technical solution, and will not be repeated here.

[0049] In the present invention, the particle size of the conductive particles is preferably 1 to 500 nm, more preferably 100 to 400 nm, and further preferably 200 to 300 nm. As an embodiment of the present invention, the particle size of the conductive particles may be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm or 450 nm. The particle size of the conductive particles is within the above range, and can be filled into the pores of the lithium-rich manganese-based spherical agglomerates or attached to the surface of the spherical agglomerates, protecting the spherical agglomerate particles during rolling, reducing the rupture of the spherical agglomerate particles caused by rolling, and is conducive to improving the cycle stability of the electrode.

[0050] In the present invention, the mass ratio of the densification auxiliary material to the modified lithium-rich manganese-based spherical agglomerates is preferably 1:(5-10), and more preferably 1:(6-9). The densification auxiliary material is added during the pulping process. The amount of the densification auxiliary material directly affects the structure of the spherical agglomerates. If the amount is too little, the pores of the lithium-rich manganese-based spherical agglomerates cannot be completely filled, and the spherical agglomerates cannot be effectively protected during the rolling process; if the amount is too much, too much densification auxiliary material will be accumulated on the surface of the lithium-rich manganese-based spherical agglomerates, affecting the entry and exit of lithium ions into the spherical agglomerates. In an embodiment of the present invention, the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates can be 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0051] The present invention has no special requirements on other preparation parameters for preparing the electrode, and the preparation parameters commonly used in the art can be adopted.

[0052] The present invention also provides a lithium-rich manganese-based electrode prepared by the preparation method described in the above technical solution, and the lithium-rich manganese-based electrode has good cycle stability.

[0053] The present invention also provides the application of the lithium-rich manganese-based electrode described in the above technical solution in a lithium-containing energy storage device.

[0054] The present invention has no special requirements for the specific application method, and the application method commonly used in the art can be adopted.

[0055] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Example 1

[0057] 500 g of lithium-rich manganese-based spherical aggregates (Shandong Chuangneng New Materials Co., Ltd., 0.5 Li 2 MnO 3 0.5LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) and 50g of lithium lanthanum zirconium tantalum oxide powder (particle size of 300nm) were mixed using a high-speed mixer (1000rpm, 2h) to obtain modified lithium-rich manganese-based spherical agglomerates.

[0058] Example 2

[0059] 500 g of lithium-rich manganese-based spherical agglomerates and 50 g of lithium lanthanum zirconium tantalum oxide powder were mixed evenly using a high-speed mixer and then sintered in a box furnace at 700° C. for 10 hours to obtain modified lithium-rich manganese-based spherical agglomerates.

[0060] Example 3

[0061] 500 g of lithium-rich manganese-based spherical agglomerates and 20 g of single-crystal nano nickel-cobalt-manganese oxide powder (particle size of 50 nm) were mixed evenly using a high-speed mixer to obtain modified lithium-rich manganese-based spherical agglomerates.

[0062] Example 4

[0063] 500 g of lithium-rich manganese-based spherical agglomerates and 50 g of lithium lanthanum zirconium tantalum oxide powder (particle size of 300 nm) were mixed with N-methylpyrrolidone (1000 mL) solvent, mixed evenly using a high-speed mixer, and then sintered in a tubular furnace at 700° C. for 20 hours to obtain modified lithium-rich manganese-based spherical agglomerates.

[0064] Example 5

[0065] 270 g of the modified lithium-rich manganese-based spherical aggregates prepared in Example 1, 15 g of conductive carbon black (Kejing), and 15 g of polyvinylidene fluoride (Alfa) were mixed in N-methylpyrrolidone solvent (Aladdin reagent), and the solid content was adjusted to 50%. The mixture was mixed evenly with a Kejing mixer (3000 rpm, 1 h), and placed in a coating machine for double-sided coating on aluminum foil. The single-sided coating amount was 30 mg / cm 2 , and dried in a vacuum oven at 120°C; at 2.4 g / cm 3 The electrode is rolled to obtain a lithium-rich manganese-based electrode.

[0066] Example 6

[0067] The modified lithium-rich manganese-based spherical aggregates prepared in Example 2 were made into lithium-rich manganese-based electrodes in the manner of Example 5.

[0068] Example 7

[0069] The modified lithium-rich manganese-based spherical agglomerates prepared in Example 3 were made into lithium-rich manganese-based electrodes in the manner of Example 5.

[0070] Example 8

[0071] The modified lithium-rich manganese-based spherical agglomerates prepared in Example 4 were made into lithium-rich manganese-based electrodes in the manner of Example 5.

[0072] Example 9

[0073] 240 g of the modified lithium-rich manganese-based spherical aggregates in Example 2, 300 g of lithium lanthanum zirconium tantalum oxide dispersant (particle size 300 nm, 10% wt), 15 g of conductive carbon black (Kejing), and 15 g of polyvinylidene fluoride (Alfa) were mixed in a certain amount of N-methylpyrrolidone solvent (Aladdin reagent), and the solid content was adjusted to 50%. The mixture was mixed evenly with a Kejing mixer (3000 rpm, 1 h), and placed in a coating machine for double-sided coating on aluminum foil. The single-sided coating amount was 30 mg / cm 2 , and dried in a vacuum oven at 120°C; at 2.4 g / cm 3 The electrode is rolled to obtain a lithium-rich manganese-based electrode.

[0074] Example 10

[0075] The raw materials and preparation method are the same as those in Example 9, except that the compacted density is 1.8 g / cm 3 .

[0076] Embodiment 11

[0077] The raw materials and preparation method are the same as those in Example 9, except that the compacted density is 2.1 g / cm 3 .

[0078] Example 12

[0079] The raw materials and preparation method are the same as those in Example 9, except that the compacted density is 2.7 g / cm 3 .

[0080] Example 13

[0081] The raw materials and preparation method are the same as those in Example 9, except that the compacted density is 3.3 g / cm 3 .

[0082] Comparative Example 1

[0083] The raw materials and preparation method are the same as those in Example 9, except that the compacted density is 3.6 g / cm 3 .

[0084] Comparative Examples 2 to 7

[0085] The raw materials and preparation method are the same as those in Example 5, except that the modified lithium-rich manganese-based spherical aggregates are replaced by lithium-rich manganese-based spherical aggregates, and the compacted densities are 1.8 g / cm 3 , 2.1g / cm 3 , 2.4g / cm 3 , 2.7g / cm 3 、3.3g / cm 3 、3.6g / cm 3 .

[0086] Comparative Examples 8 to 10

[0087] The raw materials and preparation method are the same as those in Example 5, except that lithium-rich manganese-based spherical agglomerates are used to replace the modified lithium-rich manganese-based spherical agglomerates, and in addition, 30 g of lithium lanthanum zirconium tantalum oxide powder (particle size 300 nm), 30 g of lithium aluminum titanium phosphate powder (particle size 300 nm), and 300 g of lithium lanthanum zirconium tantalum oxide dispersant (particle size 300 nm, 10% wt) are added during the slurrying process.

[0088] Application Examples

[0089] The lithium-rich manganese-based electrodes prepared in Examples 5 to 13 and Comparative Examples 1 to 10 were die-cut into suitable sizes and assembled with graphite negative electrode sheets into soft-pack cells, wherein the NP ratio was 1.15:1.

[0090] The obtained soft-pack cells were assembled into soft-pack batteries and then electrochemically tested. The first cycle was charged and discharged at a current density of 20 mA / g in the voltage range of 2.0 to 4.7 V, and then the charge and discharge cycle test was carried out at a current density of 200 mA / g in the voltage range of 2.0 to 4.5 V.

[0091] The electrochemical data of the soft pack test of each embodiment and comparative example are shown in Table 1.

[0092] Table 1 Soft pack test electrochemical performance record

[0093]

[0094]

[0095] The electrodes prepared in Example 9 and Comparative Example 4 were observed using a scanning electron microscope, and the SEM images were as follows: Figure 1 , Figure 2 As shown. Figure 1 and Figure 2It can be seen that the surface of the lithium-rich manganese-based spherical agglomerate particles in the electrode prepared in Example 9 is denser, while there are more pores on the surface of the lithium-rich manganese-based spherical agglomerates in the electrode prepared in Comparative Example 4; there are also pores in the electrode of Comparative Example 4 (between the spherical agglomerate particles), while the electrode of Example 9 is relatively dense.

[0096] The electrochemical cycle stability test results of Examples 5 to 9, Comparative Examples 4, and Comparative Examples 8 to 10 are summarized in Table 1. As can be seen from Table 1, the modified lithium-rich manganese-based spherical aggregates prepared by the preparation method provided by the present invention can effectively improve the cycle capacity retention rate of the battery, and there will be no cycle drop after 200 cycles; the electrodes (Comparative Examples 8 to 10) prepared by the method for preparing electrodes provided by the present invention using ordinary lithium-rich manganese-based spherical aggregates can stably perform electrochemical charge and discharge behavior after 200 cycles, but the capacity retention rate is relatively low.

[0097] The electrodes prepared in Example 12, Example 13 and Comparative Example 1 were observed using a scanning electron microscope, and the SEM images were as follows: Figure 3 , Figure 4 , Figure 5 As shown. Figure 4 , Figure 5 As can be seen from Table 1, the compacted density is 3.3 g / cm 3 When the electrode is prepared, it has stable cycle performance; Figure 6 From Table 1, it can be seen that when the compaction density is higher than 3.3 g / cm 3 And reach 3.6g / cm 3 After that, cracks appeared on the particles (marked in red in the figure), the cycle stability gradually decreased and a diving phenomenon occurred, and it was no longer possible to complete the 200 cycle test. This shows that too high a compaction density will cause the lithium-rich manganese-based spherical agglomerate particles to break and reduce the electrochemical performance of the electrode.

[0098] The electrode prepared in Comparative Example 6 was observed using a scanning electron microscope, and the SEM image was obtained as follows: Figure 6 As shown. Figure 6 As can be seen from Table 1, without using the modified lithium-rich manganese-based spherical aggregates provided by the present invention, and without using the preparation method of the electrode provided by the present invention, the compaction density is 3.3 g / cm 3 The particles are almost completely crushed, and the cycle stability of the prepared electrode is very poor.

[0099] It can be seen from the above embodiments and comparative examples that the preparation method of the modified lithium-rich manganese-based spherical agglomerates of the present invention can reduce the porosity of the lithium-rich manganese-based spherical agglomerates, increase the tap density, thereby reducing the contact interface between the material and the electrolyte, and can improve the cycle stability of the lithium-rich manganese-based electrode.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing modified lithium-rich manganese-based spherical aggregates, comprising: The lithium-rich manganese-based spherical agglomerates are mixed with a densification auxiliary material to obtain modified lithium-rich manganese-based spherical agglomerates; the mass ratio of the densification auxiliary material to the lithium-rich manganese-based spherical agglomerates is 1:(8-25); the densification auxiliary material is a conductive particle with a particle size of 1-500nm.

2. The preparation method according to claim 1, characterized in that: The densification auxiliary material includes one or more of a lithium-containing material and a carbon material, and the lithium-containing material includes one or more of an oxide solid electrolyte material, a sulfide solid electrolyte material, and a halide solid electrolyte material.

3. The preparation method according to claim 1, characterized in that: The mixing includes dry mixing the lithium-rich manganese-based spherical agglomerates with the densification auxiliary material or wet mixing the lithium-rich manganese-based spherical agglomerates with the densification auxiliary material in a solvent.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The method further comprises sintering after the densification auxiliary material is mixed with the lithium-rich manganese-based spherical agglomerates.

5. The preparation method according to claim 4, characterized in that: The sintering temperature is 600-800°C.

6. The modified lithium-rich manganese-based spherical aggregates prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The tap density of the modified lithium-rich manganese-based spherical aggregates is 1.5 to 3.5 g / cm 3 .

7. A method for preparing a lithium-rich manganese-based electrode, comprising: A conductive agent, a binder, a modified lithium-rich manganese-based spherical aggregate and a solvent are mixed to prepare a slurry, and then the slurry is coated on a current collector, and then dried and rolled in sequence to obtain a lithium-rich manganese-based electrode, wherein the modified lithium-rich manganese-based spherical aggregate is the modified lithium-rich manganese-based spherical aggregate according to claim 6, and the compaction density of the rolling is 1.8 to 3.3 g / cm 3 .

8. The preparation method according to claim 7, characterized in that: During the mixing and slurrying, a densification auxiliary material is added, wherein the densification auxiliary material is conductive particles with a particle size of 1 to 500 nm; the mass ratio of the densification auxiliary material to the modified lithium-rich manganese-based spherical agglomerates is 1:(5 to 10).

9. The lithium-rich manganese-based electrode prepared by the preparation method according to claim 7 or 8.

10. Use of the lithium-rich manganese-based electrode according to claim 9 in lithium-containing energy storage devices.

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