In-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material as well as preparation method and application thereof

Abstract

A preparation method of an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps: carrying out a co-precipitation reaction on an aqueous solution of more than two of a nickel source, a cobalt source and a manganese source, a precipitant and a complexing agent to obtain a hydroxide suspension; sequentially washing, filtering and drying the hydroxide suspension to obtain a composite material precursor; mixing the composite material precursor with a first amount of a lithium source solid phase, and sintering for the first time to obtain a lithium-rich manganese-based positive electrode material matrix oxide material; mixing with a second amount of a lithium source and an additive in a solid phase, and sintering for the second time to obtain an original material of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material; and finally, carrying out surface modification treatment to obtain the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material. According to the preparation method, a specific process is adopted, the overall relatively good interaction is realized, and the lithium-rich manganese-based positive electrode material with a stable surface structure and high initial efficiency is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and more specifically to an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material and a preparation method and application thereof. Background Art

[0002] The "dual carbon" goal has further promoted the vigorous development of green energy in my country. Among various green energy sources, lithium-ion batteries, as a chemical power source with high specific energy density, cyclic charging and discharging, and environmental friendliness, have been widely used in 3C fields such as mobile phones and computers, and have become one of the strong candidates for power sources for hybrid and pure electric vehicles.

[0003] The energy density that can be achieved by common lithium-ion secondary batteries at present is <300Wh / kg, which cannot meet the requirements of the cruising range of pure electric vehicles. Therefore, the energy density of existing batteries needs to be greatly improved. However, increasing the energy density of batteries will reduce their safety and easily cause thermal runaway and explosion, which seriously limits the application of lithium-ion batteries in large-scale energy storage fields such as electric vehicles. In terms of energy density, high-energy-density lithium-ion batteries often require high-specific energy positive and negative electrode materials. Therefore, in recent years, high-discharge specific capacity positive electrode materials have attracted more and more attention. Among them, lithium-rich manganese-based positive electrode materials can simultaneously utilize the activity of anion redox on the basis of transition metal redox, so that their discharge capacity is greater than 300mAh / g. However, due to the poor kinetic properties of lithium-rich manganese-based positive electrode materials, they are often prepared by particle nano-crystalization, such as by carbonate co-precipitation method. The primary particles are nano-scale and the secondary particles are micron-scale spherical carbonate precursors, and then the high-capacity lithium-rich manganese-based positive electrode materials are obtained by lithium mixing, sintering, and surface modification. However, this high-capacity lithium-rich manganese-based cathode material has a low compaction density and a large specific surface area due to the secondary spherical particles formed by the docking of the primary nanoparticles. It has serious side reactions with the electrolyte under high voltage systems, and produces gas, making it difficult to achieve long cycles. Therefore, reducing the specific surface area of ​​the material, such as developing lithium-rich manganese-based cathode materials based on hydroxide precursors, has attracted much attention; however, due to the small specific surface area and slow lithium ion diffusion rate of the hydroxide precursor during the sintering process, the lithium-rich phase is enriched in the surface layer of the secondary spherical particles of the lithium-rich manganese-based cathode material, resulting in low coulombic efficiency during the first charge and discharge process of the lithium-rich manganese-based cathode material, which has brought about problems such as difficulty in exerting the material's gram capacity, which has been troubling relevant personnel in the industry.

[0004] In summary, in order to achieve a high-energy-density battery system while solving the problem of poor cycle stability, the development of high-energy-density lithium-ion battery positive electrode materials has attracted much attention in recent years; lithium-rich manganese-based positive electrode materials have significant characteristics such as high capacity and high safety, but their cycle stability is poor, especially the voltage decay caused by oxygen release during the cycle. At the same time, due to the high manganese content and large specific surface area of ​​the material, the material suffers from serious problems such as rapid electrolyte consumption during high-voltage cycles and easy breakage of particles during the cycle, which have become technical problems that need to be urgently solved by technical personnel in this field. Summary of the invention

[0005] In view of this, the object of the present invention is to provide an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material and its preparation method and application. The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material prepared by the preparation method provided by the present invention has high compaction density and good cycle stability, and can be used to further prepare high energy density and long life lithium-ion batteries.

[0006] The present invention provides a method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material, comprising the following steps:

[0007] a) coprecipitating two or more aqueous solutions of a nickel source, a cobalt source and a manganese source with a precipitant and a complexing agent to obtain a hydroxide suspension; then washing, filtering and drying the hydroxide suspension in sequence to obtain a composite material precursor;

[0008] b) The composite material precursor obtained in step a) is mixed with a first amount of lithium source solid phase and then sintered for the first time to obtain a lithium-rich manganese-based positive electrode material matrix oxide material; then mixed with a second amount of lithium source and additive solid phase and then sintered for a second time to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material raw material; finally, surface modification treatment is performed to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0009] Preferably, the temperature of the coprecipitation reaction in step a) is 45°C to 60°C, the stirring speed is 500r / min to 700r / min, the reaction pH is 10 to 12, and the reaction time is 40h to 110h.

[0010] Preferably, the chemical formula of the composite material precursor in step a) is Mn x Ni y Co z (OH)2;

[0011] Where, 0.5≤x<1, 0.1 <y<0.5,0≤z<0.3。

[0012] Preferably, the lithium source in step b) is selected from one or more of lithium carbonate, lithium hydroxide, lithium sulfate, lithium nitrate, lithium chloride, and lithium oxide;

[0013] The molar ratio of the total metal of the composite material precursor to the first amount of lithium source and the second amount of lithium source is (0.1-0.7): (0.6-0.9):1.

[0014] Preferably, the temperature of the first sintering in step b) is 680° C. to 860° C., and the time is 4 h to 18 h;

[0015] The temperature of the second sintering is 900° C. to 960° C., and the time is 10 h to 18 h.

[0016] Preferably, the additive in step b) is selected from one or more of aluminum oxide, niobium oxide, lanthanum oxide, titanium dioxide, germanium oxide, zirconium oxide, phosphoric acid, and silicon dioxide;

[0017] The molar ratio of the matrix oxide material of the lithium-rich manganese-based positive electrode material to the additive is 1: (0.01-0.15).

[0018] Preferably, the in-situ constructed solid electrolyte in step b) is LiZr2(PO4)3, LiTi2(PO4)3, LiGe2(PO4)3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3、Li 1.5 Al 0.5 Ge 1.5 (PO4)3, Li7La3Zr2O 12 , Li 3x La 2 / 3-x TiO3、Li 10 GeP2S 12 、Li3PS4、LiClO4、Li 6.75 Ln3Z 1.75 Ta 0.25 O 12 , Li 0.33 La 0.557 TiO3, Li3PO4, LiNbO3, Li 1.35 Al 0.35 Ge 0.2 Ti 1.45 (PO4)3、Li 6.25 Ga 0.25 La3Zr2O 12 , Li 6.25 Fe 0.25 La3Zr2O 12 , Li 6.5 Ln3Z1.5 Ta 0.5 O 12 , Li 6.5 Ln3Z 1.75 Te 0.25 O 12 , Li 6.65 Ga 0.15 Ln3Z 1.90 Sc 0.10 O 12 , Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 、Li3PS4、Li7P2S8I、Li7P3S 11 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 9.54 Si 1.74 P 1.44 S 11.4 Cl 0.3 O 0.3 , Li 10 SnP2S 12 , Li 5.5 PS 4.5 Cl 1.5 , Li 5.3 PS 4.3 ClBr 0.7 , Li 6.6 P 0.4 Ge 0.6 S5I、Li 6.6 Si 0.6 Sb 0.4 S5I, Li3InCl6, Li3YCl6, Li3YBr6, Li3ScCl6, Li2Sc 2 / 3 Cl4、Li3Y 0.1 In 0.9 Cl6, Li3YBr3Cl3, Li 2.5 Y 0.5 Zr 0.5 Cl6、Li3YBr 5.7 F 0.3 One or more of .

[0019] The present invention also provides an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material, which is prepared using the preparation method described in the above technical solution.

[0020] The present invention also provides a positive electrode plate for a lithium-ion battery, which is obtained by coating a positive electrode slurry on a positive electrode collector, followed by drying, slicing, and roller pressing; the positive electrode slurry is obtained by mixing a positive electrode material, a conductive agent, carbon nanotubes, and a binder in a mass ratio of (180-200): (5-7): 1: (2-4) and then dispersing the mixture through a solvent; the positive electrode material is the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material described in the above technical solution.

[0021] The present invention also provides a lithium ion battery, comprising the positive electrode sheet for the lithium ion battery described in the above technical solution.

[0022] The invention provides an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material and a preparation method and application thereof; the preparation method comprises the following steps: a) subjecting two or more aqueous solutions of a nickel source, a cobalt source and a manganese source to a coprecipitation reaction with a precipitant and a complexing agent to obtain a hydroxide suspension; then washing, filtering and drying the hydroxide suspension in sequence to obtain a composite material precursor; b) solid-phase mixing the composite material precursor obtained in step a) with a first amount of lithium source and then sintering for the first time to obtain a lithium-rich manganese-based positive electrode material matrix oxide material; then solid-phase mixing with a second amount of lithium source and an additive and then sintering for the second time to obtain an original material of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material; and finally surface modification treatment to obtain the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material. Compared with the prior art, the preparation method provided by the present invention adopts specific process steps to achieve better overall interaction, adopts a co-precipitation method to prepare a high-density, low-specific surface area lithium-rich manganese-based positive electrode material hydroxide precursor, adopts secondary lithium mixed sintering and combines surface doping to in-situ construct a composite solid electrolyte, thereby improving the lithium ion diffusion channel of the material, avoiding the lithium-rich manganese-based positive electrode material precursor due to excessive lithium ion concentration. During the diffusion of lithium from the surface to the core of the secondary spherical precursor, lithium is limited and the manganese element in the lithium-rich manganese-based positive electrode material precursor generates lithium-rich phase Li2MnO3, which brings about the problem of lithium-rich phase enrichment on the surface of the material, and the irreversible capacity of the lithium-rich phase Li2MnO3 is large, which directly leads to the prepared lithium-rich manganese-based positive electrode material. The initial coulombic efficiency is low, so a secondary lithium mixing sintering scheme is adopted. A small amount of lithium is mixed in the first time. During the sintering process, the diffusion resistance is small due to the low lithium concentration, so the lithium can be evenly diffused from the surface to the core, and the lithium ion diffusion channel is further diffused. The remaining lithium is mixed in the second time. Through surface doping, the doping element will preferentially form a solid electrolyte with part of the lithium, so that the lithium concentration is stably diffused from the surface of the secondary spherical particle precursor to the core. The lithium-rich phase and the layered phase of the material are evenly distributed, which is conducive to the preparation of stable high first efficiency lithium-rich manganese-based positive electrode materials. At the same time, the surface structure stability of the lithium-rich manganese-based positive electrode materials is increased, the release of oxygen during the material cycle is inhibited, the cycle stability of the lithium-rich manganese-based positive electrode materials is improved, and the low compaction density of the material is improved.

[0023] At the same time, the above-mentioned in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material can be further used to prepare high energy density and long life lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the composition distribution of hydroxide precursors of conventional high-density lithium-rich manganese-based cathode materials;

[0025] Figure 2 Schematic diagram of lithium-rich phase distribution of lithium-rich manganese-based positive electrode material obtained by normal sintering;

[0026] Figure 3 A schematic diagram of the lithium-rich phase distribution of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material prepared by the present invention is provided by the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0028] The present invention provides a method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material, comprising the following steps:

[0029] a) coprecipitating two or more aqueous solutions of a nickel source, a cobalt source and a manganese source with a precipitant and a complexing agent to obtain a hydroxide suspension; then washing, filtering and drying the hydroxide suspension in sequence to obtain a composite material precursor;

[0030] b) The composite material precursor obtained in step a) is mixed with a first amount of lithium source solid phase and then sintered for the first time to obtain a lithium-rich manganese-based positive electrode material matrix oxide material; then mixed with a second amount of lithium source and additive solid phase and then sintered for a second time to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material raw material; finally, surface modification treatment is performed to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0031] See also Figures 1 to 3 As shown, the present invention is based on a high-density, low specific surface area hydroxide precursor, and adopts surface doping to in-situ construct a composite solid electrolyte, thereby improving the lithium ion diffusion channel of the material, improving the lithium-rich phase enrichment problem on the surface of the material, and preparing a stable high first efficiency lithium-rich manganese-based positive electrode material. At the same time, it increases the surface structure stability of the lithium-rich manganese-based positive electrode material, inhibits the release of oxygen during the material cycle, improves the cycle stability of the lithium-rich manganese-based positive electrode material, and improves the low compaction density of the material.

[0032] The present invention firstly carries out coprecipitation reaction on aqueous solutions of two or more of nickel source, cobalt source and manganese source, a precipitant and a complexing agent to obtain a hydroxide suspension; then the hydroxide suspension is sequentially washed, filtered and dried to obtain a composite material precursor.

[0033] In the present invention, the nickel source is preferably a nickel-containing compound. The present invention has no special restrictions on its type and source. Commercially available raw materials for preparing lithium-rich manganese-based positive electrode materials that are well known to those skilled in the art can be used; in a preferred embodiment of the present invention, the nickel source is nickel sulfate.

[0034] In the present invention, the cobalt source is preferably a cobalt-containing compound. The present invention has no special restrictions on its type and source. Commercially available raw materials for preparing lithium-rich manganese-based positive electrode materials that are well known to those skilled in the art can be used; in a preferred embodiment of the present invention, the cobalt source is cobalt sulfate.

[0035] In the present invention, the manganese source is preferably a manganese-containing compound. The present invention has no special restrictions on its type and source. Commercially available raw materials for preparing lithium-rich manganese-based positive electrode materials that are well known to those skilled in the art can be used; in a preferred embodiment of the present invention, the manganese source is manganese sulfate.

[0036] In a preferred embodiment of the present invention, aqueous solutions of nickel source, cobalt source and manganese source are subjected to coprecipitation reaction with a precipitant and a complexing agent; in another preferred embodiment of the present invention, aqueous solutions of nickel source and manganese source are subjected to coprecipitation reaction with a precipitant and a complexing agent.

[0037] In the present invention, the precipitant is preferably a sodium hydroxide solution well known to those skilled in the art for preparing lithium-rich manganese-based positive electrode materials, and the complexing agent is preferably an ammonia solution well known to those skilled in the art for preparing lithium-rich manganese-based positive electrode materials, and the present invention has no special restrictions on this.

[0038] In a preferred embodiment of the present invention, the precipitant is a 5mol / L to 10mol / L sodium hydroxide solution, the complexing agent is a 0.5mol / L to 1.5mol / L ammonia solution; and the aqueous solution of two or more of the nickel source, cobalt source and manganese source is a mixed solution of 1mol / L to 3mol / L.

[0039] In the present invention, the coprecipitation reaction process is preferably carried out in a coprecipitation reactor well known to those skilled in the art. The raw materials, sodium hydroxide solution, ammonia solution and mixed solution are preferably added to the coprecipitation reactor via a metering pump. On this basis, it is convenient to control the pH to be stable within a suitable range by adjusting the flow rate of the alkali (sodium hydroxide solution, ammonia solution).

[0040] In the present invention, the temperature of the coprecipitation reaction is preferably 45°C to 60°C, more preferably 50°C to 56°C, the stirring speed is preferably 500 r / min to 700 r / min, more preferably 600 r / min to 650 r / min, the reaction pH value is preferably 10 to 12, more preferably 10.2 to 11.3, and the reaction time is preferably 40 h to 110 h, more preferably 45 h to 105 h.

[0041] In the present invention, the coprecipitation reaction yields a hydroxide suspension, and then the above-mentioned hydroxide suspension is successively washed with water, filtered, and dried to obtain a composite material precursor; the present invention has no special limitations in this regard. In the present invention, the composite material precursor is a secondary spherical particle formed by stacking primary lamellar particles; the primary lamellar particles are preferably a lithium-rich manganese-based cathode material precursor with a size of 50 nm to 500 nm, and the particle size of the secondary spherical particles of the lithium-rich manganese-based cathode material precursor is preferably 3 μm to 30 μm; the surface area of the lithium-rich manganese-based cathode material precursor is preferably 10 m 2 / g to 30 m 2 / g.

[0042] In the present invention, the chemical formula of the composite material precursor is preferably Mn x Ni y Co z (OH)2;

[0043] In the formula, 0.5 ≤ x < 1, preferably 0.5 ≤ x ≤ 0.667, 0.1 < y < 0.5, preferably 0.166 ≤ y ≤ 0.4, 0 ≤ z < 0.3, preferably 0 ≤ z ≤ 0.25. The present invention determines the molar ratio of the raw material nickel source, cobalt source, and manganese source according to the chemical formula of the specific composite material precursor.

[0044] After obtaining the composite material precursor, the present invention solid-phase mixes the obtained composite material precursor with a first dosage of a lithium source and then conducts a first sintering to obtain a lithium-rich manganese-based cathode material matrix oxide material; then it is solid-phase mixed with a second dosage of a lithium source and an additive and undergoes a second sintering to obtain a raw material of a lithium-rich manganese-based cathode material with an in-situ constructed solid electrolyte composite; finally, through surface modification treatment, a lithium-rich manganese-based cathode material with an in-situ constructed solid electrolyte composite is obtained.

[0045] The present invention uses coprecipitation to synthesize a lithium-rich manganese-based cathode material precursor, which is a secondary spherical precursor. Through the first low-lithium pre-sintering and the second lithium mixing process, elements such as lanthanum, zirconium, niobium, and aluminum are introduced, and under the action of additives, a lithium-rich manganese-based cathode material with an in-situ formed solid electrolyte composite is obtained.

[0046] In the present invention, the lithium source is preferably selected from one or more of lithium carbonate, lithium hydroxide, lithium sulfate, lithium nitrate, lithium chloride, and lithium oxide, more preferably lithium carbonate; the present invention has no special restrictions on the source of the lithium source, and commercially available products familiar to those skilled in the art can be used.

[0047] In the present invention, the molar ratio of the total metal of the composite material precursor to the first amount of lithium source and the second amount of lithium source is preferably (0.1-0.7):(0.6-0.9):1, more preferably (0.5-0.7):(0.6-0.8):1; in the present invention, the first amount is preferably less than or equal to the second amount.

[0048] In the present invention, the temperature of the first sintering is preferably 680°C to 860°C, more preferably 690°C to 850°C, and the time is preferably 4h to 18h, more preferably 5h to 16h; on this basis, the obtained lithium-rich manganese-based positive electrode material matrix oxide material can be expressed as Li a Mn x Ni y Co z O2; where 0.1≤a≤0.7.

[0049] In the present invention, the additive is preferably selected from one or more of aluminum oxide, niobium oxide, lanthanum oxide, titanium dioxide, germanium oxide, zirconium oxide, phosphoric acid, and silicon dioxide, and more preferably two or more of aluminum oxide, lanthanum oxide, titanium dioxide, germanium oxide, zirconium oxide, and phosphoric acid; the present invention has no special restrictions on the source of the additive, and commercially available products well known to those skilled in the art can be used.

[0050] In the present invention, the molar ratio of the matrix oxide material of the lithium-rich manganese-based positive electrode material to the additive is preferably 1:(0.01-0.15), and more preferably 1:(0.03-0.1).

[0051] In the present invention, the temperature of the second sintering is preferably 900°C to 960°C, preferably 910°C to 950°C, and the time is preferably 10h to 18h, more preferably 12h to 16h; during the second sintering process, a lithium-rich manganese-based positive electrode material with a solid electrolyte composite structure can be generated in situ, and on this basis, a lithium-rich manganese-based positive electrode material raw material with an in-situ solid electrolyte composite is obtained.

[0052] In the present invention, the in-situ constructed solid electrolyte is preferably LiZr2(PO4)3(LZP), LiTi2(PO4)3(LTP), LiGe2(PO4)3(LGP), Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP), Li 1.5Al 0.5 Here 1.5 (PO4)3(LAGP)、Li7La3Zr2O 12 (LLZO)、The 3x The 2 / 3-x TiO3、Li 10 GeP2S 12 、Li3PS4、LiClO4、Li 6.75 The3Zr 1.75 Pile 0.25 O 12 ,He 0.33 The 0.557 TiO3(LLTO)、Li3PO4、LiNbO3、Li 1.35 Al 0.35 Here 0.2 Was 1.45 (PO4)3、Li 6.25 Ga 0.25 The3Zr2O 12 ,He 6.25 Fact 0.25 The3Zr2O 12 ,He 6.5 The3Zr 1.5 Pile 0.5 O 12 ,He 6.5 The3Zr 1.75 Tea 0.25 O 12 ,He 6.65 Ga 0.15 The3Zr 1.90 Sc 0.10 O 12 ,He 6.5 The3Zr 1.5 Pile 0.5 O 12 、Li3PS4、Li7P2S8I、Li7P3S 11 ,He 10 GeP2S 12 ,He 9.54 If 1.74 P 1.44 S 11.7 Cl 0.3 ,He 9.54 If 1.74 P 1.44 S 11.4 Cl 0.3 O 0.3 ,He 10 SnP2S 12 ,He 5.5 PS4.5 Cl 1.5 , Li 5.3 PS 4.3 ClBr 0.7 , Li 6.6 P 0.4 Ge 0.6 S5I、Li 6.6 Si 0.6 Sb 0.4 S5I, Li3InCl6, Li3YCl6, Li3YBr6, Li3ScCl6, Li2Sc 2 / 3 Cl4、Li3Y 0.1 In 0.9 Cl6, Li3YBr3Cl3, Li 2.5 Y 0.5 Zr 0.5 Cl6、Li3YBr 5.7 F 0.3 One or more of, more preferably Li7La3Zr2O 12 (LLZO), Li 0.33 La 0.557 TiO3(LLTO), Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP), Li 1.5 Al 0.5 Ge 1.5 One or both of (PO4)3(LAGP).

[0053] Finally, the present invention subjects the obtained in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material to surface modification treatment to obtain the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0054] The present invention has no special limitation on the process of the surface modification treatment, and for example, a surface water washing technical solution well known to those skilled in the art may be adopted.

[0055] The present invention also provides an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material, which is prepared by the preparation method described in the above technical solution. In the present invention, the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material is a high-capacity, long-life cycle lithium-rich manganese-based positive electrode material.

[0056] The present invention also provides a positive electrode plate for a lithium-ion battery, which is obtained by coating a positive electrode slurry on a positive electrode collector, followed by drying, slicing, and roller pressing; the positive electrode slurry is obtained by mixing a positive electrode material, a conductive agent, carbon nanotubes, and a binder in a mass ratio of (180-200): (5-7): 1: (2-4) and then dispersing the mixture through a solvent; the positive electrode material is the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material described in the above technical solution.

[0057] The present invention adopts the above-mentioned in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material as the positive electrode material of the lithium-ion battery. The high capacity, high safety, long cycle and high compaction lithium-rich manganese-based positive electrode material is suitable for preparing high energy density and long life lithium-ion batteries.

[0058] In the present invention, the conductive agent is preferably SP; the binder is preferably PVDF; the solvent is preferably NMP; the present invention has no special restrictions on the sources of the above raw materials, and commercial products known to those skilled in the art can be used.

[0059] In the present invention, the positive electrode slurry is obtained by mixing the positive electrode material, the conductive agent, the carbon nanotubes and the binder in a mass ratio of (180-200): (5-7): 1: (2-4) and then dispersing them through a solvent, preferably by mixing the positive electrode material, the conductive agent, the carbon nanotubes and the binder in a mass ratio of (180-200): 6: 1: 3 and then dispersing them through a solvent.

[0060] The present invention also provides a lithium ion battery, comprising the positive electrode sheet for the lithium ion battery described in the above technical solution.

[0061] In the present invention, the lithium-ion battery also includes a negative electrode plate, which is preferably made of a negative electrode material; the negative electrode material is preferably selected from one or more of natural graphite, artificial graphite, silicon-carbon material, lithium metal negative electrode, and lithium carbon negative electrode material, and more preferably one or more of silicon-carbon material, lithium metal negative electrode, and lithium carbon negative electrode material; in addition, the lithium-ion battery also includes materials such as a diaphragm, thereby assembling a high-energy lithium-ion battery; in a preferred embodiment of the present invention, the above-mentioned positive and negative electrode plates are preferably assembled into a 25Ah battery cell by lamination or winding; the battery can operate within any voltage range after being activated above 4.55V in the first cycle.

[0062] In summary, the present invention provides an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material and its preparation method and application; based on a high-density and low-specific surface area hydroxide precursor, a surface doping composite solid electrolyte is in-situ constructed, thereby improving the lithium ion diffusion channel of the material, avoiding the lithium-rich manganese-based positive electrode material precursor due to excessive lithium ion concentration. During the diffusion of lithium from the surface to the core of the secondary spherical precursor, lithium is limited and the manganese element in the lithium-rich manganese-based positive electrode material precursor generates lithium-rich phase Li2MnO3, which brings about the problem of lithium-rich phase enrichment on the surface of the material, and the lithium-rich phase Li The large irreversible capacity of 2MnO3 directly leads to the low first coulombic efficiency of the prepared lithium-rich manganese-based positive electrode material. Through surface doping, the doping elements will preferentially form a solid electrolyte with part of the lithium, so that the lithium concentration can stably diffuse from the surface of the secondary spherical particle precursor to the core. The lithium-rich phase and the layered phase of the material are evenly distributed, which is conducive to the preparation of stable high first efficiency lithium-rich manganese-based positive electrode materials. At the same time, the surface structure stability of the lithium-rich manganese-based positive electrode materials is increased, the release of oxygen during the material cycle is inhibited, the cycle stability of the lithium-rich manganese-based positive electrode materials is improved, and the low compaction density of the material is improved.

[0063] The invention provides an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material and a preparation method and application thereof; the preparation method comprises the following steps: a) subjecting two or more aqueous solutions of a nickel source, a cobalt source and a manganese source to a coprecipitation reaction with a precipitant and a complexing agent to obtain a hydroxide suspension; then washing, filtering and drying the hydroxide suspension in sequence to obtain a composite material precursor; b) solid-phase mixing the composite material precursor obtained in step a) with a first amount of lithium source and then sintering for the first time to obtain a lithium-rich manganese-based positive electrode material matrix oxide material; then solid-phase mixing with a second amount of lithium source and an additive and then sintering for the second time to obtain an original material of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material; and finally surface modification treatment to obtain the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material. Compared with the prior art, the preparation method provided by the present invention adopts specific process steps to achieve better overall interaction, adopts a co-precipitation method to prepare a high-density, low-specific surface area lithium-rich manganese-based positive electrode material hydroxide precursor, adopts secondary lithium mixed sintering and combines surface doping to in-situ construct a composite solid electrolyte, thereby improving the lithium ion diffusion channel of the material, avoiding the lithium-rich manganese-based positive electrode material precursor due to excessive lithium ion concentration. During the diffusion of lithium from the surface to the core of the secondary spherical precursor, lithium is limited and the manganese element in the lithium-rich manganese-based positive electrode material precursor generates lithium-rich phase Li2MnO3, which brings about the problem of lithium-rich phase enrichment on the surface of the material, and the irreversible capacity of the lithium-rich phase Li2MnO3 is large, which directly leads to the prepared lithium-rich manganese-based positive electrode material. The initial coulombic efficiency is low, so a secondary lithium mixing sintering scheme is adopted. A small amount of lithium is mixed in the first time. During the sintering process, the diffusion resistance is small due to the low lithium concentration, so the lithium can be evenly diffused from the surface to the core, and the lithium ion diffusion channel is further diffused. The remaining lithium is mixed in the second time. Through surface doping, the doping element will preferentially form a solid electrolyte with part of the lithium, so that the lithium concentration is stably diffused from the surface of the secondary spherical particle precursor to the core. The lithium-rich phase and the layered phase of the material are evenly distributed, which is conducive to the preparation of stable high first efficiency lithium-rich manganese-based positive electrode materials. At the same time, the surface structure stability of the lithium-rich manganese-based positive electrode materials is increased, the release of oxygen during the material cycle is inhibited, the cycle stability of the lithium-rich manganese-based positive electrode materials is improved, and the low compaction density of the material is improved.

[0064] At the same time, the above-mentioned in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material can be further used to prepare high energy density and long life lithium-ion batteries.

[0065] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0066] Example 1

[0067] A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps:

[0068] (1) nickel sulfate, cobalt sulfate and manganese sulfate compounds are prepared into a 2 mol / L mixed solution in a molar ratio of 1:1:4; then the mixed solution, a 5 mol / L sodium hydroxide solution as a precipitant and a 1.5 mol / L ammonia solution as a complexing agent are added into a coprecipitation reactor through a metering pump, the reactor temperature is controlled at 50°C, the stirring speed is 650 r / min, and the reaction pH value is between 10.5 and 11.2, and the coprecipitation reaction is carried out for 45 hours to obtain a nickel-cobalt-manganese hydroxide suspension; then the nickel-cobalt-manganese hydroxide suspension is washed with water, filtered and dried in sequence to obtain a nickel-cobalt-manganese composite material precursor; the nickel-cobalt-manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel, cobalt and manganese, and the chemical formula is Ni 0.166 Co 0.166 Mn 0.667 (OH)2.

[0069] (2) The above nickel-cobalt-manganese composite material precursor Ni 0.166 Co 0.166 Mn 0.667 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.6 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at 750℃ for 16 hours to obtain Li 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0070] (3) The above Li 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material and lithium source lithium carbonate are mixed at a molar ratio of Li:Me=0.8. 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material and additives in a molar ratio of 1:0.03, lanthanum oxide and zirconium oxide (the molar ratio of lanthanum oxide and zirconium oxide is 3:2) are added for solid phase mixing, and sintered at a high temperature of 950 ° C for 16 hours to obtain the in-situ constructed solid electrolyte Li7La3Zr2O 12 (LLZO) composite lithium-rich manganese-based positive electrode material raw material.

[0071] (4) The above-mentioned in-situ solid electrolyte Li7La3Zr2O 12 The original material of the (LLZO) composite lithium-rich manganese-based positive electrode material is surface-modified (surface washed) to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0072] Application Example 1

[0073] (1) The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 1 is used as an active material in a mass ratio of 95%, and 3% conductive agent SP, 0.5% carbon nanotubes, 1.5% binder PVDF and solvent NMP are added together in a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0074] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0075] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0076] The lithium-ion battery is charged to above 4.55V for the first cycle and activated, and then cycled within a voltage range of 2.3 to 4.5V.

[0077] After testing, the tap density of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 1 reached 2.0 g / cc, and the specific surface area of ​​the material was 2.85 m 2 / g, the material's first-cycle discharge capacity reaches 285mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 86%.

[0078] The compaction density of the positive electrode material pole piece obtained in step (1) of Application Example 1 is as high as 3.2g / cc, and the initial efficiency of the assembled full battery reaches 90%. Within the voltage range of 2 to 4.55V of the full battery, the energy density of the battery reaches 375Wh / Kg at 0.1C discharge. The capacity retention rate of the full battery after 800 cycles within the voltage range of 2.3 to 4.5V is 90%, and no gas is generated during the cycle, which is suitable for the basic application requirements of high specific energy power batteries.

[0079] Example 2

[0080] A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps:

[0081] (1) nickel sulfate, cobalt sulfate and manganese sulfate compounds are prepared into a 2 mol / L mixed solution in a molar ratio of 1:1:3; then the mixed solution, 10 mol / L sodium hydroxide solution as a precipitant and 1 mol / L ammonia solution as a complexing agent are added to a coprecipitation reactor through a metering pump, and the reactor temperature is controlled to 55°C, the stirring speed is 600 r / min, and the reaction pH value is between 10.7 and 11.3, and the coprecipitation reaction is carried out for 85 hours to obtain a nickel-cobalt-manganese hydroxide suspension; then the nickel-cobalt-manganese hydroxide suspension is washed with water, filtered, and dried in sequence to obtain a nickel-cobalt-manganese composite material precursor; the nickel-cobalt-manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel, cobalt and manganese, and the chemical formula is Ni 0.2 Co 0.2 Mn 0.6 (OH)2.

[0082] (2) The above nickel-cobalt-manganese composite material precursor Ni 0.2 Co 0.2 Mn 0.6 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.5 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at a high temperature of 765°C for 8 hours to obtain Li 0.5 Ni 0.2 Co 0.2 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0083] (3) The above Li 0.5 Ni 0.2 Co 0.2 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material and lithium source lithium carbonate are mixed at a molar ratio of Li:Me=0.8. 0.5 Ni 0.2 Co 0.2 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material and additive molar ratio of 1:0.04 was added to lanthanum oxide and titanium dioxide (the molar ratio of lanthanum oxide and titanium dioxide was 0.557:1) for solid phase mixing, and sintered at high temperature of 925℃ for 14 hours to obtain in-situ constructed solid electrolyte Li 0.33 La 0.557 TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material raw material.

[0084] (4) The above-mentioned in-situ constructed solid electrolyte Li 0.33 La 0.557The original material of TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material is subjected to surface modification treatment (surface water washing) to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0085] Application Example 2

[0086] (1) The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 2 is used as an active material in a mass ratio of 95%, and 3% conductive agent SP, 0.5% carbon nanotubes, 1.5% binder PVDF and solvent NMP are added together in a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0087] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0088] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0089] The lithium-ion battery is charged to above 4.55V for the first cycle and activated, and then cycled within a voltage range of 2.3 to 4.5V.

[0090] After testing, the tap density of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 2 reached 2.2 g / cc, and the specific surface area of ​​the material was 2.85 m 2 / g, the material's first-cycle discharge capacity reaches 275mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 88%.

[0091] The compaction density of the positive electrode material pole piece obtained in step (1) of Application Example 2 is as high as 3.0g / cc, and the initial efficiency of the assembled full battery reaches 90%. Within the voltage range of 2 to 4.55V of the full battery, the energy density of the battery reaches 350Wh / Kg when discharged at 0.1C, and the capacity retention rate of the full battery after 800 cycles within the voltage range of 2.3 to 4.5V is 85.1%, and no gas is generated during the cycle, which is suitable for the basic application requirements of high specific energy power batteries.

[0092] Example 3

[0093] A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps:

[0094] (1) nickel sulfate, cobalt sulfate and manganese sulfate compounds are prepared into a 2 mol / L mixed solution in a molar ratio of 1:1:4; then the mixed solution, a 5 mol / L sodium hydroxide solution as a precipitant and a 1.5 mol / L ammonia solution as a complexing agent are added into a coprecipitation reactor through a metering pump, the reactor temperature is controlled at 50°C, the stirring speed is 650 r / min, and the reaction pH value is between 10.5 and 11.2, and the coprecipitation reaction is carried out for 45 hours to obtain a nickel-cobalt-manganese hydroxide suspension; then the nickel-cobalt-manganese hydroxide suspension is washed with water, filtered and dried in sequence to obtain a nickel-cobalt-manganese composite material precursor; the nickel-cobalt-manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel, cobalt and manganese, and the chemical formula is Ni 0.166 Co 0.166 Mn 0.667 (OH)2.

[0095] (2) The above nickel-cobalt-manganese composite material precursor Ni 0.166 Co 0.166 Mn 0.667 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.6 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at a high temperature of 850°C for 8 hours to obtain Li 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0096] (3) The above Li 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material and lithium source lithium carbonate are mixed at a molar ratio of Li:Me=0.8. 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material and additives in a molar ratio of 1:0.08, aluminum oxide, titanium dioxide, germanium oxide, phosphorus source (aluminum oxide, titanium dioxide, germanium oxide, phosphorus source molar ratio of 8:17:15:6) were added for solid phase mixing, and sintered at a high temperature of 910 ° C for 15 hours to obtain an in-situ solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) and Li 1.5 Al0.5 Ge 1.5 The raw material of lithium-rich manganese-based positive electrode material is composited with a (PO4)3(LAGP) molar ratio of 1:1.

[0097] (4) The above-mentioned in-situ constructed solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) and Li 1.5 Al 0.5 Ge 1.5 The original material of the lithium-rich manganese-based positive electrode material composited with a (PO4)3(LAGP) molar ratio of 1:1 was subjected to surface modification treatment (surface water washing) to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0098] Application Example 3

[0099] (1) The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 3 is used as an active material in a mass ratio of 95%, and 3% conductive agent SP, 0.5% carbon nanotubes, 1.5% binder PVDF and solvent NMP are added together in a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0100] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0101] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0102] The lithium-ion battery is charged to above 4.55V for the first cycle and then activated and cycled within a voltage range of 2.3 to 4.5V.

[0103] After testing, the tap density of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 3 reached 2.0 g / cc, and the specific surface area of ​​the material was 2.85 m 2 / g, the material's first-cycle discharge capacity reaches 280mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 86%.

[0104] The compaction density of the positive electrode material pole piece obtained in step (1) of Application Example 3 is as high as 3.2g / cc, and the initial efficiency of the assembled full battery reaches 90%. Within the voltage range of 2 to 4.55V of the full battery, the energy density of the battery reaches 350Wh / Kg when discharged at 0.1C, and the capacity retention rate of the full battery after 800 cycles within the voltage range of 2.3 to 4.5V is 95%, and no gas is generated during the cycle, which is suitable for the basic application requirements of high specific energy power batteries.

[0105] Example 4

[0106] A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps:

[0107] (1) nickel sulfate, cobalt sulfate and manganese sulfate compounds are prepared into a 2 mol / L mixed solution in a molar ratio of 1:1:2; then the mixed solution, a precipitant sodium hydroxide solution of 10 mol / L and a complexing agent ammonia solution of 0.5 mol / L are added to a coprecipitation reactor through a metering pump, and the reactor temperature is controlled to 56°C, the stirring speed is 600 r / min, and the reaction pH value is between 10.2 and 11.0, and the coprecipitation reaction is carried out for 55 hours to obtain a nickel-cobalt-manganese hydroxide suspension; then the nickel-cobalt-manganese hydroxide suspension is washed with water, filtered, and dried in turn to obtain a nickel-cobalt-manganese composite material precursor; the nickel-cobalt-manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel, cobalt and manganese, and the chemical formula is Ni 0.25 Co 0.25 Mn 0.5 (OH)2.

[0108] (2) The above nickel-cobalt-manganese composite material precursor Ni 0.25 Co 0.25 Mn 0.5 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.6 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at a high temperature of 690°C for 12 hours to obtain Li 0.6 Ni 0.25 Co 0.25 Mn 0.5 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0109] (3) The above Li 0.6 Ni 0.25 Co 0.25 Mn 0.5O2 lithium-rich manganese-based positive electrode material matrix oxide material and lithium source lithium carbonate are mixed at a molar ratio of Li:Me=0.6. 0.6 Ni 0.25 Co 0.25 Mn 0.5 O2 lithium-rich manganese-based positive electrode material matrix oxide material and additive molar ratio of 1:0.1 was added to lanthanum oxide and titanium dioxide (the molar ratio of lanthanum oxide and titanium dioxide was 0.557:1) for solid phase mixing, and sintered at high temperature of 950 ° C for 12 hours to obtain in-situ constructed solid electrolyte Li 0.33 La 0.557 TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material raw material.

[0110] (4) The above-mentioned in-situ constructed solid electrolyte Li 0.33 La 0.557 The original material of TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material is subjected to surface modification treatment (surface water washing) to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0111] Application Example 4

[0112] (1) The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 4 is used as an active material at a mass ratio of 95%, and 3% conductive agent SP, 0.5% carbon nanotubes, 1.5% binder PVDF and solvent NMP are added together in a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0113] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0114] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0115] The lithium-ion battery is charged to above 4.55V for the first cycle and then activated and cycled within a voltage range of 2.3 to 4.5V.

[0116] After testing, the tap density of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 4 reached 2.25 g / cc, and the specific surface area of ​​the material was 2.65 m 2 / g, the material's first-cycle discharge capacity reaches 255mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 84%.

[0117] The compaction density of the positive electrode material obtained in step (1) of Example 4 is as high as 3.2g / cc, and the initial efficiency of the assembled full battery reaches 90%. Within the voltage range of 2 to 4.55V of the full battery, the energy density of the battery reaches 300Wh / Kg when discharged at 0.1C, and the capacity retention rate of the full battery after 800 cycles within the voltage range of 2.3 to 4.5V is 91%, and no gas is generated during the cycle, which is suitable for the basic application requirements of high-energy-density power batteries.

[0118] Example 5

[0119] A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps:

[0120] (1) nickel sulfate, cobalt sulfate and manganese sulfate compounds are prepared into a 2 mol / L mixed solution in a molar ratio of 3.5:0.5:6; then the mixed solution, 10 mol / L sodium hydroxide solution as a precipitant and 1.5 mol / L ammonia solution as a complexing agent are added to a coprecipitation reactor through a metering pump, and the reactor temperature is controlled at 56°C, the stirring speed is 600 r / min, and the reaction pH value is between 10.9 and 11.3, and the coprecipitation reaction is carried out for 55 hours to obtain a nickel-cobalt-manganese hydroxide suspension; then the nickel-cobalt-manganese hydroxide suspension is washed with water, filtered, and dried in turn to obtain a nickel-cobalt-manganese composite material precursor; the nickel-cobalt-manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel, cobalt and manganese, and the chemical formula is Ni 0.35 Co 0.05 Mn 0.6 (OH)2.

[0121] (2) The above nickel-cobalt-manganese composite material precursor Ni 0.35 Co 0.05 Mn 0.6 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.7 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at a high temperature of 725℃ for 5 hours to obtain Li 0.7 Ni 0.35 Co 0.05 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0122] (3) The above Li 0.7 Ni0.35 Co 0.05 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material and lithium source lithium carbonate are mixed at a molar ratio of Li:Me=0.7. 0.7 Ni 0.35 Co 0.05 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material and additive molar ratio of 1:0.05 was added to lanthanum oxide and titanium dioxide (the molar ratio of lanthanum oxide and titanium dioxide was 0.557:1) for solid phase mixing, and sintered at high temperature of 925℃ for 16 hours to obtain in-situ constructed solid electrolyte Li 0.33 La 0.557 TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material raw material.

[0123] (4) The above-mentioned in-situ constructed solid electrolyte Li 0.33 La 0.557 The original material of TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material is subjected to surface modification treatment (surface water washing) to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0124] Application Example 5

[0125] (1) The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 5 is used as an active material at a mass ratio of 95%, and 3% conductive agent SP, 0.5% carbon nanotubes, 1.5% binder PVDF and solvent NMP are added together in a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0126] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0127] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0128] The lithium-ion battery is charged to above 4.55V for the first cycle and then activated and cycled within a voltage range of 2.3 to 4.5V.

[0129] After testing, the tap density of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 5 reached 1.95 g / cc, and the specific surface area of ​​the material was 2.25 m 2 / g, the material's first-cycle discharge capacity reaches 240mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 89%.

[0130] The compaction density of the positive electrode material pole piece obtained in step (1) of Application Example 5 is as high as 3.0g / cc, and the initial efficiency of the assembled full battery reaches 90%. Within the voltage range of 2 to 4.55V of the full battery, the energy density of the battery reaches 255Wh / Kg when discharged at 0.1C, and the capacity retention rate of the full battery after 800 cycles within the voltage range of 2.3 to 4.5V is 93%, and no gas is generated during the cycle, which is suitable for the basic application requirements of high specific energy power batteries.

[0131] Example 6

[0132] A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material comprises the following steps:

[0133] (1) nickel sulfate and manganese sulfate compound are prepared into a 2 mol / L mixed solution in a molar ratio of 4:6; then the mixed solution, 10 mol / L sodium hydroxide solution as a precipitant and 1.0 mol / L ammonia solution as a complexing agent are added into a coprecipitation reactor through a metering pump, the reactor temperature is controlled at 50°C, the stirring speed is 650 r / min, and the reaction pH value is between 10.7 and 11.3, and the coprecipitation reaction is carried out for 105 hours to obtain a nickel manganese hydroxide suspension; then the nickel manganese hydroxide suspension is washed with water, filtered, and dried in sequence to obtain a nickel manganese composite material precursor; the nickel manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel and manganese, and the chemical formula is Ni 0.4 Mn 0.6 (OH)2.

[0134] (2) The nickel-manganese composite material precursor Ni 0.4 Mn 0.6 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.7 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at a high temperature of 715°C for 8 hours to obtain Li 0.7 Ni 0.4 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0135] (3) The above Li0.7 Ni 0.4 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material and lithium source lithium carbonate are mixed at a molar ratio of Li:Me=0.7. 0.7 Ni 0.4 Mn 0.6 O2 lithium-rich manganese-based positive electrode material matrix oxide material and additive molar ratio of 1:0.05 was added to lanthanum oxide and titanium dioxide (the molar ratio of lanthanum oxide and titanium dioxide was 0.557:1) for solid phase mixing, and sintered at high temperature of 950 ° C for 16 hours to obtain in-situ constructed solid electrolyte Li 0.33 La 0.557 TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material raw material.

[0136] (4) The above-mentioned in-situ constructed solid electrolyte Li 0.33 La 0.557 The original material of TiO3 (LLTO) composite lithium-rich manganese-based positive electrode material is subjected to surface modification treatment (surface water washing) to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

[0137] Application Example 6

[0138] (1) The in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 6 is used as an active material at a mass ratio of 95%, and 3% conductive agent SP, 0.5% carbon nanotubes, 1.5% binder PVDF and solvent NMP are added together in a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0139] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0140] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0141] The lithium-ion battery is charged to above 4.55V for the first cycle and then activated and cycled within a voltage range of 2.3 to 4.5V.

[0142] After testing, the tap density of the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material provided in Example 6 reached 1.90 g / cc, and the specific surface area of ​​the material was 2.55 m 2 / g, the material's first-cycle discharge capacity reaches 255mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 86%.

[0143] The compaction density of the positive electrode material obtained in step (1) of Application Example 6 is as high as 3.0g / cc, and the initial efficiency of the assembled full battery reaches 90%. The energy density of the battery reaches 250Wh / Kg when discharged at 0.1C within the voltage range of 2 to 4.55V for the full battery, and the capacity retention rate after 800 cycles within the voltage range of 2.3 to 4.5V for the full battery is 95%, and no gas is generated during the cycle, which is suitable for the basic application requirements of high-energy-density power batteries.

[0144] Comparative Example 1

[0145] A method for preparing a lithium-rich manganese-based positive electrode material comprises the following steps:

[0146] (1) nickel sulfate, cobalt sulfate and manganese sulfate compounds are prepared into a 2 mol / L mixed solution in a molar ratio of 1:1:4; then the mixed solution, a 5 mol / L sodium hydroxide solution as a precipitant and a 1.5 mol / L ammonia solution as a complexing agent are added into a coprecipitation reactor through a metering pump, the reactor temperature is controlled at 50°C, the stirring speed is 650 r / min, and the reaction pH value is between 10.5 and 11.2, and the coprecipitation reaction is carried out for 45 hours to obtain a nickel-cobalt-manganese hydroxide suspension; then the nickel-cobalt-manganese hydroxide suspension is washed with water, filtered and dried in sequence to obtain a nickel-cobalt-manganese composite material precursor; the nickel-cobalt-manganese composite material precursor is a lithium-rich manganese-based positive electrode material precursor containing nickel, cobalt and manganese, and the chemical formula is Ni 0.166 Co 0.166 Mn 0.667 (OH)2.

[0147] (2) The above nickel-cobalt-manganese composite material precursor Ni 0.166 Co 0.166 Mn 0.667 (OH)2 and lithium carbonate were mixed in the solid phase according to the molar ratio of Li:Me = 0.6 (Me refers to the total metal, i.e. the sum of nickel, cobalt and manganese), and then sintered at 750℃ for 6 hours to obtain Li 0.6 Ni 0.166 Co 0.166 Mn 0.667 O2 lithium-rich manganese-based positive electrode material matrix oxide material.

[0148] (3) The above Li 0.6Ni 0.166 Co 0.166 Mn 0.667 The O2 lithium-rich manganese-based positive electrode material matrix oxide material is mixed with the lithium source lithium carbonate in a molar ratio of Li:Me=0.8, and sintered at a high temperature of 925°C for 14 hours to obtain the lithium-rich manganese-based positive electrode material raw material.

[0149] (4) The above-mentioned lithium-rich manganese-based positive electrode material raw material is subjected to surface modification treatment (surface water washing) to obtain a lithium-rich manganese-based positive electrode material.

[0150] Application Comparative Example 1

[0151] (1) The lithium-rich manganese-based positive electrode material provided in Comparative Example 1 is used as an active material at a mass ratio of 95%, and 3% of a conductive agent SP, 0.5% of carbon nanotubes, 1.5% of a binder PVDF and a solvent NMP are added together, and added into a batching kettle and stirred evenly to obtain a lithium-ion battery composite positive electrode material slurry; the above-mentioned lithium-ion battery composite positive electrode material slurry is coated on the positive electrode collector, and the electrode sheet is dried, sliced, and rolled to obtain a positive electrode material electrode sheet for standby use.

[0152] (2) A silicon-carbon composite negative electrode material (produced by Ningbo Fuli Battery Material Technology Co., Ltd., with a discharge capacity of 820 mAh / g) is used as an active material at a mass ratio of 95%, and 2% of a conductive agent (SP: carbon nanotubes = 1:1), 3% of a binder CMC and a solvent SBR are added to a batching kettle and stirred evenly to obtain a lithium-ion battery negative electrode material slurry; the above lithium-ion battery negative electrode material slurry is coated on the negative electrode current collector, and the electrode sheet is dried, sliced, and rolled to obtain a negative electrode material electrode sheet for standby use.

[0153] (3) Assembling the above-mentioned positive and negative electrode material plates into a 25Ah battery cell by stacking; then baking the above-mentioned battery cell, injecting electrolyte, and forming it to obtain a lithium-ion battery.

[0154] The lithium-ion battery is charged to above 4.55V for the first cycle and then activated and cycled within a voltage range of 2.3 to 4.5V.

[0155] After testing, the tap density of the lithium-rich manganese-based positive electrode material provided in Comparative Example 1 reached 2.0 g / cc, and the specific surface area of ​​the material was 2.95 m 2 / g, the material's first-cycle discharge capacity reaches 217mAh / g in the half-cell voltage range of 2 to 4.8V, and the material's first coulombic efficiency of the half-cell reaches 74%.

[0156] The compaction density of the positive electrode material obtained in step (1) of comparative example 1 is as high as 3.2g / cc, and the initial efficiency of the assembled full battery reaches 73%. The energy density of the battery reaches 255Wh / Kg at 0.1C discharge within the voltage range of 2 to 4.55V for the full battery, and the capacity retention rate is 60% after 800 cycles within the voltage range of 2.3 to 4.5V for the full battery, and no gas is generated during the cycle.

[0157] Compared with Comparative Example 1, Example 1 of the present invention uses an in-situ constructed electrolyte to first improve the coulombic efficiency of the first cycle charge and discharge of the positive electrode material. At the same time, the surface solid electrolyte is beneficial to improving the material interface stability and improving the cycle stability of the battery.

[0158] The test result data is shown in Table 1 below.

[0159] Table 1 Performance comparison between the examples and the comparative examples

[0160]

[0161] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an in-situ solid electrolyte composite lithium-rich manganese-based positive electrode material, characterized in that: The following steps are involved: a) coprecipitating two or more aqueous solutions of a nickel source, a cobalt source and a manganese source with a precipitant and a complexing agent to obtain a hydroxide suspension; then washing, filtering and drying the hydroxide suspension in sequence to obtain a composite material precursor; b) The composite material precursor obtained in step a) is mixed with a first amount of lithium source solid phase and then sintered for the first time to obtain a lithium-rich manganese-based positive electrode material matrix oxide material; then mixed with a second amount of lithium source and additive solid phase and then sintered for a second time to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material raw material; finally, surface modification treatment is performed to obtain an in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material.

2. The preparation method according to claim 1, characterized in that: The temperature of the coprecipitation reaction in step a) is 45° C. to 60° C., the stirring speed is 500 r / min to 700 r / min, the reaction pH value is 10 to 12, and the reaction time is 40 h to 110 h.

3. The preparation method according to claim 1, characterized in that: The chemical formula of the composite material precursor in step a) is Mn x Ni y Co z (OH)2; Where, 0.5≤x<1, 0.1 <y<0.5,0≤z<0.3。 4. The preparation method according to claim 1, characterized in that: The lithium source in step b) is selected from one or more of lithium carbonate, lithium hydroxide, lithium sulfate, lithium nitrate, lithium chloride and lithium oxide; The molar ratio of the total metal of the composite material precursor to the first amount of lithium source and the second amount of lithium source is (0.1-0.7): (0.6-0.9):

1.

5. The preparation method according to claim 1, characterized in that: The temperature of the first sintering in step b) is 680° C. to 860° C., and the time is 4 h to 18 h; The temperature of the second sintering is 900° C. to 960° C., and the time is 10 h to 18 h.

6. The preparation method according to claim 1, characterized in that: The additive in step b) is selected from one or more of aluminum oxide, niobium oxide, lanthanum oxide, titanium dioxide, germanium oxide, zirconium oxide, phosphoric acid, and silicon dioxide; The molar ratio of the matrix oxide material of the lithium-rich manganese-based positive electrode material to the additive is 1: (0.01-0.15).

7. The preparation method according to claim 1, characterized in that: The in-situ constructed solid electrolyte described in step b) is LiZr2(PO4)3, LiTi2(PO4)3, LiGe2(PO4)3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, Li7La3Zr2O 12 、Li 3x La 2 / 3-x TiO3, Li 10 GeP2S 12 、Li3PS4, LiClO4, Li 6.75 La3Zr 1.75 Ta 0.25 O 12 、Li 0.33 La 0.557 TiO3, Li3PO4, LiNbO3, Li 1.35 Al 0.35 Ge 0.2 Ti 1.45 (PO4)3, Li 6.25 Ga 0.25 La3Zr2O 12 、Li 6.25 Fe 0.25 La3Zr2O 12 、Li 6.5 La3Zr 1.5 Ta 0.5 O 12 、Li 6.5 La3Zr 1.75 Te 0.25 O 12 、Li 6.65 Ga 0.15 La3Zr 1.90 Sc 0.10 O 12 、Li 6.5 La3Zr 1.5 Ta 0.5 O 12 、Li3PS4, Li7P2S8I, Li7P3S 11 、Li 10 GeP2S 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 、Li 9.54 Si 1.74 P 1.44 S 11.4 Cl 0.3 O 0.3 , Li 10 SnP2S 12 , Li 5.5 PS 4.5 Cl 1.5 , Li 5.3 PS 4.3 ClBr 0.7 , Li 6.6 P 0.4 Ge 0.6 S5I、Li 6.6 Si 0.6 Sb 0.4 S5I, Li3InCl6, Li3YCl6, Li3YBr6, Li3ScCl6, Li2Sc 2 / 3 Cl4、Li3Y 0.1 In 0.9 Cl6, Li3YBr3Cl3, Li 2.5 Y 0.5 Zr 0.5 Cl6、Li3YBr 5.7 F 0.3 One or more of .

8. An in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material, characterized in that: The preparation method is described in any one of claims 1 to 7.

9. A positive electrode sheet for a lithium-ion battery, which is obtained by coating a positive electrode slurry on a positive electrode current collector, followed by drying, slicing, and roller pressing; the positive electrode slurry is obtained by mixing a positive electrode material, a conductive agent, carbon nanotubes, and a binder in a mass ratio of (180-200): (5-7): 1: (2-4) and then dispersing the mixture through a solvent; characterized in that: The positive electrode material is the in-situ constructed solid electrolyte composite lithium-rich manganese-based positive electrode material as described in claim 8.

10. A lithium ion battery, characterized in that: The invention comprises the positive electrode sheet for lithium-ion battery as claimed in claim 9.

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