A nickel-manganese binary composite positive electrode material and preparation method thereof

Abstract

The present invention discloses a nickel-manganese binary composite cathode material and a preparation method thereof. The chemical formula of the nickel-manganese binary composite cathode material is Li(Ni x Mn y M 1‑x‑y ) z X 1‑z O2@mMe, where 0.5 ≤ x < 1, 0 < y ≤ 0.5, and 1 - x - y ≠ 0, 0.9 ≤ z ≤ 1, 0 ≤ m ≤ 0.1, 1 - z and m cannot be 0 at the same time; Me is coated on the surface of Li(Ni x Mn y M 1‑x‑y ) z X 1‑z O2; M is at least one of Y, W, Mo, Al, etc.; X is at least one of Ti, Ta, Ce, etc.; Me is at least one of PPy, PANI, Li2WO4, etc. The nickel-manganese binary composite cathode material has better thermal stability, discharge specific capacity, and excellent cycle stability compared with LiNi x Mn 1‑x O2. Its preparation method has simple and easy steps, convenient operation, less environmental pollution, low cost, excellent economic benefits, and good application value.

Description

Technical Field

[0001] The present invention belongs to the field of battery materials, and in particular relates to a nickel-manganese binary composite positive electrode material and a preparation method thereof. Background Art

[0002] With the growing demand for automobiles and portable electronics, reducing the cost of lithium-ion batteries (LIBs) has become a key driver. Since cathode materials dominate the battery cost, maximizing the performance of cathode materials while pursuing high energy density and low cost has become a dual goal of the battery industry. High nickel (Ni) and low cobalt or cobalt-free (Co) layered cathode materials have received increasing research attention in the battery community for two main reasons: first, higher nickel content provides higher battery voltage and discharge capacity; second, the use of cobalt is restricted by its limited reserves, high price, and ecological unfriendliness. Therefore, LiNi x Mn 1-x O2 (0.5≤x<1) positive electrode materials have attracted people's attention.

[0003] However, the most common disadvantages of high-nickel, low-cobalt or cobalt-free cathode materials are low thermal stability, inevitable structural degradation, and poor cycling stability due to increased Ni content. Therefore, improving these shortcomings of nickel-manganese binary cathode materials has become a top priority. Summary of the Invention

[0004] The present invention aims to overcome the aforementioned drawbacks of high-nickel, low-cobalt, or cobalt-free cathode materials by providing a nickel-manganese binary composite cathode material and a method for preparing the same. This nickel-manganese binary composite cathode material exhibits high initial discharge capacity and strong cycling stability. Its preparation method is simple, rational, and relatively low-cost.

[0005] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0006] The nickel-manganese binary composite positive electrode material provided by the present invention has a chemical formula of Li(Ni x Mn y M 1-x-y ) z X 1-zO2@mMe, where 0.5 ≤ x < 1, 0 < y ≤ 0.5, and 1 - x - y ≠ 0, 0.9 ≤ z ≤ 1, 0 ≤ m ≤ 0.1, and 1 - z and m cannot be 0 at the same time; M is a doping element, including at least one of Zr, Ba, Sr, B, Mg, Ca, Co, Nb, Y, W, Mo, Al; X is a high-valence element, including at least one of Zr, Nb, W, Mo, Ti, Ta, Ce; Me is a coating agent, including at least one of Al2O3, TiO2, Nb2O5, CeO2, Li2ZrO3, Li3PO4, FePO4, Li7La3Zr2O 12 、LiNbO3、LiNi 0.5 Mn 1.5 O4、Li4Ti5O 12 、PPy (polypyrrole), PANI (polyaniline), Li2WO4; Me is distributed on the surface of Li(Ni x Mn y M 1-x-y ) z X 1-z O2, forming a coating on Li(Ni x Mn y M 1-x-y ) z X 1-z O2.

[0007] In the present invention, m refers to the mass ratio of the coating agent Me to Li(Ni x Mn y M 1-x-y ) z X 1-z O2.

[0008] For the nickel-manganese binary composite cathode material described above, its primary particle size is 0.2 - 1.2 μm, and the secondary particle size D50 is 3.0 - 7.0 μm.

[0009] For the nickel-manganese binary composite cathode material described above, its specific surface area is 0.5 ± 0.2 m 2 / g.

[0010] The present invention also provides a preparation method for the nickel-manganese binary composite cathode material, including the following steps:

[0011] 1) Using nickel salt, manganese salt, and M source as raw materials, synthesize a spherical hydroxide precursor Ni x Mn y M 1-x-y (OH)2;

[0012] 2) Mix the precursor powder prepared in step 1) with a lithium source and an additive containing element X to obtain a mixture;

[0013] 3) The mixture obtained in step 2) is sintered in an oxygen atmosphere and then cooled naturally to obtain a nickel-manganese binary positive electrode material Li (Ni x Mn y M 1-x-y ) z X 1-z O2;

[0014] 4) The positive electrode material obtained in step 3) is mixed with the coating agent Me to obtain a nickel-manganese binary composite positive electrode material Li (Ni x Mn y M 1-x-y ) z X 1-z O2@mMe.

[0015] Preferably, in step 1), the nickel salt is selected from one or more of nickel sulfate, nickel nitrate, and nickel halide.

[0016] Preferably, in step 1), the manganese salt is selected from one or more of manganese sulfate, manganese nitrate, and manganese halides.

[0017] Preferably, in step 1), the M source is selected from one or more of sulfuric acid M, nitric acid M, M halide, and M acid salt, wherein M is selected from one or more of Zr, Ba, Sr, B, Mg, Ca, Co, Nb, Y, W, Mo, and Al.

[0018] Preferably, in step 2), the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium acetate and lithium nitrate.

[0019] Preferably, in step 2), the additive containing element X is selected from oxides or inorganic salts of one or more elements selected from Zr, Nb, W, Mo, Ti, Ta, La, Yb, and Ce.

[0020] Preferably, step 2) further comprises: sieving the mixture, wherein the mesh number of the sieve is 400 meshes.

[0021] Preferably, in step 3), the sintering process conditions are: calcining at 400-600° C. for 4-8 hours, and calcining at 780-880° C. for 8-20 hours at a heating rate of 1-5° C. / min.

[0022] Preferably, in step 4), the coating agent Me is selected from Al2O3, TiO2, Nb2O5, CeO2, Li2ZrO3, Li3PO4, FePO4, Li7La3Zr2O 12 、LiNbO3、LiNi 0.5 Mn 1.5 O4、Li4Ti5O 12, PPy, PANI, Li2WO4 or more.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) LiNi binary lithium nickel manganese oxide positive electrode material x Mn 1-x O2 (0.5≤x<1) has poor rate performance due to its cobalt-free nature and low cost. However, the nickel-manganese binary composite cathode material provided by the present invention has excellent electrochemical performance. At a cutoff voltage of 4.3V and a rate of 1C, its initial discharge capacity is 163-170 mAh / g, and its capacity retention after 50 cycles is >94%.

[0025] (2) The present invention introduces doping elements in the precursor preparation stage, prepares a uniform precursor material through a co-precipitation preparation method, and stabilizes the crystal structure from the inside of the material; adds high-valent elements in the lithium mixing stage to increase the number of free electrons, thereby improving the electronic conductivity; in addition, during the sintering process, the doping elements can produce a layer of fast ion conductor on the surface, thereby improving its ion conductivity. However, doping alone cannot effectively improve the problem of side reactions occurring when the material surface contacts the electrolyte. Therefore, a coating treatment is performed on the surface of the material to suppress its side reactions with the electrolyte while improving its electronic conductivity. The material prepared by the present invention can suppress its side reactions with the electrolyte, improve the conductivity of the material, and facilitate the transmission of ions and electrons.

[0026] (3) The cathode material obtained by the present invention can exhibit excellent electrochemical performance when using different lithium sources.

[0027] (4) The preparation method of the present invention can be used to prepare a nickel-manganese binary positive electrode material with significantly improved structural stability and electrochemical performance; the preparation method of the present invention has simple steps and is easy to perform, easy to operate, has little environmental pollution, low cost, excellent economic benefits, and has great application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 XRD pattern of O2@0.01PPy;

[0029] Figure 2 The positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01The first charge and discharge curve of O2@0.01PPy;

[0030] Figure 3 The positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 Cycling performance diagram of O2@0.01PPy at 1C rate;

[0031] Figure 4 The positive electrode material Li(Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 The first charge and discharge curve of O2@0.01PPy;

[0032] Figure 5 The positive electrode material Li(Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 Cycling performance diagram of O2@0.01PPy at 1C rate;

[0033] Figure 6 The positive electrode material LiNi obtained in Example 7 0.75 Mn 0.247 W 0.003 The first charge and discharge curve of O2@0.01PPy;

[0034] Figure 7 The positive electrode material LiNi obtained in Example 7 0.75 Mn 0.247 W 0.003 Cycling performance diagram of O2@0.01PPy at 1C rate;

[0035] Figure 8 The positive electrode material LiNi obtained in Example 8 0.75 Mn 0.24 Mo 0.01 The first charge and discharge curve of O2@0.01PPy;

[0036] Figure 9 The positive electrode material LiNi obtained in Example 8 0.75 Mn 0.24 Mo 0.01 Cycling performance diagram of O2@0.01PPy at 1C rate. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described in detail below with reference to specific embodiments.

[0038] Example 1

[0039] (1) First, NiSO4·6H2O, MnSO4·H2O and Y(NO3)3·6H2O (n Ni :n Mn :n Y =0.75:0.24:0.01) were dissolved together in distilled water to prepare a 2 mol / L metal solution. Then, a peristaltic pump was used to slowly pump the prepared metal solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution were added to the reactor at a controlled flow rate. The pH value was adjusted to 11, and a coprecipitation reaction was carried out. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.24 Y 0.01 (OH)2;

[0040] (2) In terms of molar ratio, LiOH·H2O, Ni 0.75 Mn 0.24 Y 0.01 The ratio of metal ions in (OH)2 precursor material and TiO2 is Li:(Ni+Mn+Y):Ti=1.06:0.99:0.01. Weigh appropriate amount of LiOH·H2O, Ni 0.75 Mn 0.24 Y 0.01 (OH)2 and TiO2 were mixed in a high-efficiency mixer for 0.5h, and then sintered in two stages under an oxygen atmosphere, calcined at 500℃ for 4-6 hours and 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2.

[0041] Example 2

[0042] (1) Preparation of Ni precursor 0.75 Mn 0.24 Y 0.01 (OH)2: same as (1) in Example 1;

[0043] (2) In terms of molar ratio, LiOH·H2O and Ni 0.75 Mn 0.24 Y 0.01The ratio of metal ions Li:(Ni+Mn+Y) in the (OH)2 precursor material is 1.06:1. Weigh appropriate amounts of LiOH·H2O and Ni 0.75 Mn 0.24 Y 0.01 (OH)2, and after mixing in a high-efficiency mixer for 0.5h, two-stage sintering was carried out in an oxygen atmosphere, calcined at 500℃ for 4-6 hours, calcined at 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material LiNi 0.75 Mn 0.24 Y 0.01 O2;

[0044] (3) 10g of positive electrode material LiNi 0.75 Mn 0.24 Y 0.01 O2 was dissolved in anhydrous ethanol, and pyrrole monomer (100 mg) and sodium p-toluenesulfonate were mixed in a molar ratio of 3:1 (mol / mol) and added to the LiNi 0.75 Mn 0.24 Y 0.01 The mixture was placed in anhydrous ethanol solution of O2 and ultrasonicated for 30 minutes to make it uniformly dispersed. Then, under constant stirring, anhydrous ethanol solution of FeCl3 (100 mg dissolved in 10 ml of anhydrous ethanol) was added dropwise to initiate polymerization. The reaction was carried out in an ice bath for 24 hours. After the product was obtained, it was filtered, washed with anhydrous ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain the positive electrode material LiNi 0.75 Mn 0.24 Y 0.01 O2@0.01PPy.

[0045] Example 3

[0046] (1) Preparation of Ni precursor 0.75 Mn 0.24 Y 0.01 (OH)2: same as (1) in Example 1;

[0047] (2) Preparation of positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2: same as (2) in Example 1;

[0048] (3) 10g of positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01O2 was dissolved in anhydrous ethanol, and pyrrole monomer (100 mg) and sodium p-toluenesulfonate were mixed in a molar ratio of 3:1 (mol / mol) and added to the Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2 anhydrous ethanol solution, ultrasonicated for 30 minutes to make it uniformly dispersed. Then, under continuous stirring, FeCl3 anhydrous ethanol solution (100 mg dissolved in 10 ml anhydrous ethanol) was added dropwise to initiate polymerization. The reaction was carried out in an ice bath for 24 hours. After the product was obtained, it was filtered, washed with anhydrous ethanol, and dried in a vacuum oven at 60 ° C for 12 hours to obtain the positive electrode material Li (Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2@0.01PPy.

[0049] Figure 1 For the positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 The XRD pattern of O2@0.01PPy shows that the main diffraction peak corresponds to the typical hexagonal layered α-NaFeO2 structure with space group R-3m, revealing the obvious layered structural characteristics of the material.

[0050] Figure 2 The positive electrode material is Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 The first charge and discharge curve of O2@0.01PPy.

[0051] Figure 3 The positive electrode material is Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 Cycling performance diagram of O2@0.01PPy at 1C rate.

[0052] Example 4

[0053] (1) Preparation of Ni precursor 0.75 Mn 0.24 Y 0.01 (OH)2: same as (1) in Example 3;

[0054] (2) In terms of molar ratio, Li2CO3 and Ni0.75 Mn 0.24 Y 0.01 (OH)2 precursor material metal ion Li: (Ni + Mn + Y): Ti = 1.06: 0.99: 0.01 ratio, weigh appropriate amount of Li2CO3, Ni 0.75 Mn 0.24 Y 0.01 (OH)2 and TiO2. The obtained Ni 0.75 Mn 0.24 Y 0.01 (OH)2 precursor material, Li2CO3 and TiO2 were uniformly mixed and mixed in a high-efficiency mixer for 0.5h; two-stage sintering was carried out under an oxygen atmosphere, calcined at 500℃ for 4-6 hours and 815℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2;

[0055] (3) Preparation of positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2@0.01PPy: Same as (3) in Example 3.

[0056] Example 5

[0057] (1) Preparation of Ni precursor 0.75 Mn 0.24 Y 0.01 (OH)2: same as (1) in Example 3;

[0058] (2) In terms of molar ratio, LiNO3, Ni 0.75 Mn 0.24 Y 0.01 (OH)2 precursor material, the ratio of metal ions Li: (Ni + Mn + Y): Ti = 1.06: 0.99: 0.01 in TiO2, weigh appropriate amounts of LiNO3, Ni 0.75 Mn 0.24 Y 0.01 (OH)2 and TiO2 were mixed in a high-efficiency mixer for 0.5h, and then sintered in two stages under an oxygen atmosphere, calcined at 500℃ for 4-6 hours and 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2;

[0059] (3) Preparation of positive electrode material Li(Ni 0.75 Mn 0.24 Y 0.01 ) 0.99 Ti 0.01 O2@0.01PPy: Same as (3) in Example 3.

[0060] Example 6

[0061] (1) First, dissolve NiSO4·6H2O and MnSO4·H2O in distilled water to prepare a 2 mol / L metal solution, prepare a 4 mol / L NaOH solution, and dissolve Al(NO3)3(n Ni :n Mn :n Al =0.75:0.22:0.03) was dissolved in NaOH solution to prepare sodium aluminate solution. Then, a peristaltic pump was used to slowly pump the prepared nickel manganese sulfate solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution containing sodium aluminate were added to the reactor at a controlled flow rate, respectively, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.22 Al 0.03 (OH)2;

[0062] (2) In terms of molar ratio, LiOH·H2O, Ni 0.75 Mn 0.22 Al 0.03 (OH)2 precursor material, the metal ion ratio of TiO2 in Li: (Ni + Mn + Al): Ti = 1.06: 0.99: 0.01, weigh appropriate amounts of LiOH·H2O, Ni 0.75 Mn 0.22 Al 0.03 (OH)2 and TiO2 were mixed in a high-efficiency mixer for 0.5 h; two-stage sintering was carried out in an oxygen atmosphere, calcined at 500 ° C for 4 to 6 hours and 800 ° C for 12 hours, and naturally cooled to 100 ° C to take out the sample to obtain the positive electrode material Li (Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 O2;

[0063] (3) 10g of positive electrode material Li(Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti0.01 O2 was dissolved in anhydrous ethanol, and pyrrole monomer (100 mg) and sodium p-toluenesulfonate were mixed in a molar ratio of 3:1 (mol / mol) and added to the Li(Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 O2 anhydrous ethanol solution, ultrasonicated for 30 minutes to make it dispersed evenly, then under continuous stirring, FeCl3 anhydrous ethanol solution (100 mg dissolved in 10 ml anhydrous ethanol) was dropped to initiate polymerization, and the reaction was carried out in an ice bath for 24 hours. After the product was obtained, it was filtered, washed with anhydrous ethanol, and dried in a vacuum oven at 60 ° C for 12 hours to obtain the positive electrode material Li (Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 O2@0.01PPy.

[0064] Figure 4 The positive electrode material is Li(Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 The first charge and discharge curve of O2@0.01PPy;

[0065] Figure 5 The positive electrode material is Li(Ni 0.75 Mn 0.22 Al 0.03 ) 0.99 Ti 0.01 Cycling performance diagram of O2@0.01PPy at 1C rate.

[0066] Example 7

[0067] (1) First, dissolve NiSO4·6H2O and MnSO4·H2O in distilled water to prepare a 2 mol / L metal solution, prepare a 4 mol / L NaOH solution, and mix Na2WO4·2H2O (n Ni :n Mn :n W =0.75:0.247:0.003) was dissolved in NaOH solution. Then, a peristaltic pump was used to slowly pump the prepared nickel manganese sulfate solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution containing Na2WO4 were added to the reactor at a controllable flow rate, respectively, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn0.247 W 0.003 (OH)2;

[0068] (2) In terms of molar ratio, LiOH·H2O, Ni 0.75 Mn 0.247 W 0.003 The metal ion ratio of (OH)2 precursor material is Li:(Ni+Mn+W)=1.06:1, and appropriate amount of LiOH·H2O and Ni 0.75 Mn 0.247 W 0.003 (OH)2, and after mixing in a high-efficiency mixer for 0.5h, two-stage sintering was carried out in an oxygen atmosphere, calcined at 500℃ for 4-6 hours, calcined at 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material LiNi 0.75 Mn 0.247 W 0.003 O2;

[0069] (3) 10g of positive electrode material LiNi 0.75 Mn 0.247 W 0.003 O2 was dissolved in anhydrous ethanol, and pyrrole monomer (100 mg) and sodium p-toluenesulfonate were mixed in a molar ratio of 3:1 (mol / mol) and added to the LiNi 0.75 Mn 0.247 W 0.003 O2 anhydrous ethanol solution, ultrasonic treatment for 30 minutes to make it uniformly dispersed. Then, under continuous stirring, FeCl3 anhydrous ethanol solution (100 mg dissolved in 10 ml anhydrous ethanol) was added dropwise to initiate polymerization. The reaction was carried out in an ice bath for 24 hours. After the product was obtained, it was filtered, washed with anhydrous ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain the positive electrode material LiNi 0.75 Mn 0.247 W 0.003 O2@0.01PPy.

[0070] Figure 6 The positive electrode material is LiNi 0.75 Mn 0.247 W 0.003 The first charge and discharge curve of O2@0.01PPy;

[0071] Figure 7 The positive electrode material is LiNi 0.75 Mn 0.247 W 0.003 Cycling performance diagram of O2@0.01PPy at 1C rate.

[0072] Example 8

[0073] (1) First, dissolve NiSO4·6H2O and MnSO4·H2O in distilled water to prepare a 2 mol / L metal solution, prepare a 4 mol / L NaOH solution, and add Na2MoO4 (n Ni :n Mn :n Mo =0.75:0.24:0.01) was dissolved in NaOH solution. Then, a peristaltic pump was used to slowly pump the prepared nickel manganese sulfate solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution containing Na2MoO4 were added to the reactor at a controllable flow rate, respectively, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.24 Mo 0.01 (OH)2;

[0074] (2) In terms of molar ratio, LiOH·H2O and Ni 0.75 Mn 0.24 Mo 0.01 The metal ion ratio of (OH)2 precursor material is Li:(Ni+Mn+Mo)=1.06:1, and appropriate amount of LiOH·H2O and Ni 0.75 Mn 0.24 Mo 0.01 (OH)2, and after mixing in a high-efficiency mixer for 0.5h, two-stage sintering was carried out in an oxygen atmosphere, calcined at 500℃ for 4-6 hours, calcined at 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material LiNi 0.75 Mn 0.24 Mo 0.01 O2;

[0075] (3) 10g of positive electrode material LiNi 0.75 Mn 0.24 Mo 0.01 O2 was dissolved in anhydrous ethanol, and pyrrole monomer (100 mg) and sodium p-toluenesulfonate were mixed in a molar ratio of 3:1 (mol / mol) and added to the LiNi 0.75 Mn 0.24 Mo 0.01 O2 anhydrous ethanol solution, ultrasonic treatment for 30 minutes to make it uniformly dispersed. Then, under continuous stirring, FeCl3 anhydrous ethanol solution (100 mg dissolved in 10 ml anhydrous ethanol) was added dropwise to initiate polymerization. The reaction was carried out in an ice bath for 24 hours. After the product was obtained, it was filtered, washed with anhydrous ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain the positive electrode material LiNi 0.75 Mn 0.24 Mo0.01 O2@0.01PPy.

[0076] Figure 8 The positive electrode material is LiNi 0.75 Mn 0.24 Mo 0.01 The first charge and discharge curve of O2@0.01PPy;

[0077] Figure 9 The positive electrode material is LiNi 0.75 Mn 0.24 Mo 0.01 Cycling performance diagram of O2@0.01PPy at 1C rate.

[0078] Comparative Example 1

[0079] (1) First, NiSO4·6H2O and MnSO4·H2O (n Ni :n Mn =0.75:0.25) were dissolved together in distilled water to prepare a 2 mol / L metal solution. Then, a peristaltic pump was used to slowly pump the prepared nickel manganese sulfate solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution were added to the reactor at a controlled flow rate, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.25 (OH)2;

[0080] (2) In terms of molar ratio, LiOH·H2O and Ni 0.75 Mn 0.25 The metal ion ratio of (OH)2 precursor material is Li:(Ni+Mn)=1.06:1, and an appropriate amount of Ni 0.75 Mn 0.25 (OH)2 and LiOH·H2O were mixed in a high-efficiency mixer for 0.5h, and then sintered in two stages under an oxygen atmosphere, calcined at 500℃ for 4-6 hours and 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material LiNi 0.75 Mn 0.25 O2.

[0081] Comparative Example 2

[0082] (1) First, NiSO4·6H2O, MnSO4·H2O and Y(NO3)3·6H2O (n Ni :n Mn :n Y=0.75:0.24:0.01) were dissolved together in distilled water to prepare a 2 mol / L metal solution. Then, a peristaltic pump was used to slowly pump the prepared metal solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution were added to the reactor at a controllable flow rate, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.24 Y 0.01 (OH)2;

[0083] (2) In terms of molar ratio, LiOH·H2O and Ni 0.75 Mn 0.24 Y 0.01 The metal ion ratio of (OH)2 precursor material is Li:(Ni+Mn+Y)=1.06:1, and appropriate amount of LiOH·H2O and Ni 0.75 Mn 0.24 Y 0.01 (OH)2, and after mixing in a high-efficiency mixer for 0.5h, two-stage sintering was carried out in an oxygen atmosphere, calcined at 500℃ for 4-6 hours, calcined at 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material LiNi 0.75 Mn 0.24 Y 0.01 O2.

[0084] Comparative Example 3

[0085] (1) First, NiSO4·6H2O and MnSO4·H2O (n Ni :n Mn =0.75:0.25) were dissolved together in distilled water to prepare a 2 mol / L metal solution. Then, a peristaltic pump was used to slowly pump the prepared nickel manganese sulfate solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution were added to the reactor at a controlled flow rate, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.25 (OH)2;

[0086] (2) In terms of molar ratio, LiOH·H2O, Ni 0.75 Mn 0.25 (OH)2 precursor material, the ratio of metal ions Li: (Ni + Mn): Ti in TiO2 = 1.06: 0.99: 0.01, weigh appropriate amounts of LiOH·H2O, Ni 0.75 Mn 0.25(OH)2 and TiO2 were mixed in a high-efficiency mixer for 0.5h, and then sintered in two stages under an oxygen atmosphere, calcined at 500℃ for 4-6 hours and 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material Li(Ni 0.75 Mn 0.25 ) 0.99 Ti 0.01 O2.

[0087] Comparative Example 4

[0088] (1) First, NiSO4·6H2O and MnSO4·H2O (n Ni :n Mn =0.75:0.25) were dissolved together in distilled water to prepare a 2 mol / L metal solution. Then, a peristaltic pump was used to slowly pump the prepared nickel manganese sulfate solution into a continuously stirred reactor. At the same time, 2 mol / L NH4OH solution and 4 mol / L NaOH solution were added to the reactor at a controlled flow rate, and the pH value was adjusted to 11 to carry out a coprecipitation reaction. After the reaction was completed, the precursor Ni was filtered, washed with distilled water, and dried to obtain 0.75 Mn 0.25 (OH)2;

[0089] (2) In terms of molar ratio, LiOH·H2O and Ni 0.75 Mn 0.25 The ratio of metal ions Li: (Ni+Mn) in the (OH)2 precursor material is 1.06:1. Weigh an appropriate amount of Ni 0.75 Mn 0.25 (OH)2 and LiOH·H2O were mixed in a high-efficiency mixer for 0.5h, and then sintered in two stages under an oxygen atmosphere, calcined at 500℃ for 4-6 hours and 800℃ for 12 hours, and naturally cooled to 100℃ to take out the sample to obtain the positive electrode material LiNi 0.75 Mn 0.25 O2;

[0090] (3) 10g of positive electrode material LiNi 0.75 Mn 0.25 O2 was dissolved in anhydrous ethanol, and pyrrole monomer (100 mg) and sodium p-toluenesulfonate were mixed in a molar ratio of 3:1 (mol / mol) and added to the LiNi 0.75 Mn 0.25O2 anhydrous ethanol solution, ultrasonic treatment for 30 minutes to make it uniformly dispersed. Then, under continuous stirring, FeCl3 anhydrous ethanol solution (100 mg dissolved in 10 ml anhydrous ethanol) was added dropwise to initiate polymerization. The reaction was carried out in an ice bath for 24 hours. After the product was obtained, it was filtered, washed with anhydrous ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain the positive electrode material LiNi 0.75 Mn 0.25 O2@0.01PPy.

[0091] The positive electrode materials finally prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to relevant electrochemical performance tests, and the results are shown in Table 1.

[0092] Table 1 Electrochemical performance results of the positive electrode materials finally prepared in Examples 1 to 8 and Comparative Examples 1 to 4

[0093]

[0094]

[0095] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A nickel-manganese binary composite positive electrode material, characterized in that: The chemical formula of the nickel-manganese binary composite cathode material is Li(NixMnyM1-x-y)zX1-zO2@mMe, where 0.5 ≤ x < 1, 0 < y ≤ 0.5, and 1 - x - y ≠ 0, 0.9 ≤ z ≤ 1, 0 ≤ m ≤ 0.1, and 1 - z and m cannot be 0 at the same time; M is a doping element, including at least one of Zr, Ba, Sr, B, Mg, Ca, Co, Nb, Y, W, Mo, Al; X is a high-valence element, including at least one of Zr, Nb, W, Mo, Ti, Ta, Ce; Me is a coating agent, including at least one of Al2O3, TiO2, Nb2O5, CeO2, Li2ZrO3, Li3PO4, FePO4, Li7La3Zr2O12, LiNbO3, LiNi0.5Mn1.5O4, Li4Ti5O12, PPy, PANI, Li2WO4; Me is distributed on the surface of Li(NixMnyM1-x-y)zX1-zO2 to form a coating on Li(NixMnyM1-x-y)zX1-zO2.

2. The nickel-manganese binary composite positive electrode material according to claim 1, characterized in that For the nickel-manganese binary composite cathode material, the primary particle size is 0.2 - 1.2 μm, and the secondary particle size D50 is 3.0 - 7.0 μm.

3. The nickel-manganese binary composite positive electrode material according to claim 1, characterized in that The specific surface area of ​​the nickel-manganese binary composite positive electrode material is 0.5±0.2m 2 / g.

4. A method for preparing the nickel-manganese binary composite cathode material according to any one of claims 1 to 3, comprising the following steps: 1) Using nickel salt, manganese salt and M source as raw materials, synthesize spherical hydroxide precursor Ni x Mn y M 1-x-y (OH)2; 2) Mix the precursor powder prepared in step 1) with a lithium source and an additive containing element X to obtain a mixed material. 3) The mixture obtained in step 2) is sintered in an oxygen atmosphere and then cooled naturally to obtain a nickel-manganese binary positive electrode material Li(Ni x Mn y M 1-x-y ) z X 1-z O2; 4) The cathode material obtained in step 3) is mixed with the coating agent Me to obtain a nickel-manganese binary composite cathode material Li(Ni x Mn y M 1-x-y ) z X 1-z O2@mMe.

5. The preparation method according to claim 4, characterized in that In step 1), the nickel salt is selected from one or more of nickel sulfate, nickel nitrate, and nickel halides; the manganese salt is selected from one or more of manganese sulfate, manganese nitrate, and manganese halides.

6. The preparation method according to claim 4, characterized in that In step 1), the M source is selected from one or more of sulfate M, nitrate M, halides of M, and salts of M acid radicals, where M is selected from one or more of Zr, Ba, Sr, B, Mg, Ca, Co, Nb, Y, W, Mo, Al.

7. The preparation method according to claim 4, characterized in that In step 2), the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate; the additive containing element X is selected from oxides or inorganic salts containing one or more elements of Zr, Nb, W, Mo, Ti, Ta, Ce.

8. The preparation method according to claim 4, characterized in that Step 2) further includes: passing the mixed material through a sieving process with a sieve mesh size of 400 mesh.

9. The preparation method according to claim 4, characterized in that In step 3), the process conditions for sintering are: with a heating rate of 1 - 5 °C / min, calcining at 400 - 600 °C for 4 - 8 hours, and calcining at 780 - 880 °C for 8 - 20 hours.

10. The preparation method according to claim 4, characterized in that In step 4), the coating agent Me is selected from Al2O3, TiO2, Nb2O5, CeO2, Li2ZrO3, Li3PO4, FePO4, Li7La3Zr2O 12 、LiNbO3、LiNi 0.5 Mn 1.5 O4、Li4Ti5O 12 , PPy, PANI, Li2WO4 or more.

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