CN112086638B - Method for reducing alkalinity of positive electrode material by using phosphorus-containing organic matter - Google Patents
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Abstract
The invention provides a method for reducing alkalinity of a positive electrode material by using a phosphorus-containing organic matter, which is realized by obtaining the positive electrode material with the surface coated with lithium phosphate. According to the invention, phosphorus element in an organic compound is utilized, and a lithium phosphate surface coating layer is constructed in a non-aqueous system, so that adverse effect of water on the battery anode material is completely avoided, residual lithium on the surface is consumed while the structural stability of the battery anode material is maintained, and the alkalinity of the anode material is effectively reduced; a uniform lithium phosphate coating layer is constructed on the surface of the battery anode material, so that the stability and the electrochemical performance of the battery anode material in the air are improved. The phosphorus-containing organic compound utilized by the invention has wide source and low cost; the liquid phase method is adopted, the condition is mild, the process is simple and effective, and the industrial production is easy to realize.
Description
Technical Field
The invention belongs to the field of lithium ion battery anode materials, and particularly relates to a method for reducing the alkalinity of an anode material by using a phosphorus-containing organic substance.
Background
Electric vehicles are an important field of national planning and development. Endurance is the core competitiveness of electric vehicles. The high-energy-density lithium ion battery has important significance for improving the endurance mileage of the electric automobile. Compared with a negative electrode material, a positive electrode material of the lithium ion battery has low specific capacity, and is one of bottlenecks that the energy density of the lithium ion battery is limited to be improved.
Too strong alkalinity is an obstacle for restricting the application of some lithium ion battery anode materials. Using nickel-rich cathode material (LiNi)xCoyMn1-x-yO2(x is more than or equal to 60 percent)) as an example, the nickel-rich cathode material improves the proportion of nickel in the material, and compared with cobalt element forming the cathode material of the lithium ion battery, the nickel has the advantages of high specific capacity, low price, environmental friendliness and the like. Nickel-rich cathode materialThe material has the characteristics of high specific capacity and low cost, and is widely concerned by people. However, a series of problems still exist with nickel-rich cathode materials, one important problem being excessive basicity. The alkalinity of the nickel-rich cathode material mainly comes from residual lithium on the surface of the nickel-rich cathode material. In the process of preparing the nickel-rich cathode material, in order to prevent the loss of lithium, an excessive amount of lithium salt is usually added, and the excessive amount of lithium salt causes excessive lithium on the surface of the product, namely residual lithium on the surface. Residual lithium is easy to react with H in humid air2O，CO2Reaction to produce LiOH, Li2CO3. These two substances enhance the basicity of the nickel-rich cathode material. The strong basicity enables the nickel-rich positive electrode material to be easily changed into jelly in the homogenizing process, and coating is affected; the strong basicity increases the water absorption capacity of the nickel-rich cathode material, and a large amount of water can be brought into the battery in the battery assembling process, so that the decomposition of electrolyte is promoted, a series of problems such as gas expansion and the like are caused, and the electrochemical performance and the safety performance of the battery are deteriorated. It is very necessary to modify the surface of the lithium ion battery anode material including the nickel-rich anode material to reduce the alkalinity of the lithium ion battery anode material.
Researchers widely adopt liquid phase surface modification means such as washing and the like to carry out surface modification on the lithium ion battery anode material so as to reduce alkalinity. The liquid phase surface modification means has the advantages of uniform mixing, simple and convenient operation and the like, and is widely concerned by people. We have noted that the existing liquid phase surface modification means are almost all carried out in aqueous systems, which is disadvantageous for some lithium ion battery positive electrode materials. For example, for nickel-rich cathode materials, aqueous processing schemes suffer from the following disadvantages: the water can replace lithium in the nickel-rich anode material to generate LiOH, so that the specific capacity of the nickel-rich anode material is irreversibly reduced; the sensitivity of the water-treated nickel-rich cathode material to humid air is enhanced, and lithium carbonate and lithium hydroxide are easier to generate; the nickel-rich cathode material treated by water has poor thermal stability and low high-temperature performance. The korean lithium battery specialist Jaephil Cho drafted: treatment of nickel-rich cathode material in water is not a good method, and we should seek better alternatives to it (Junhyeok Kim et al adv Energy mater.2018,8,1702028).
Chinese patent CN 102881911A reports a scheme for constructing a lithium phosphate coating layer by using a liquid phase precipitation method, but the scheme cannot avoid the adverse effect of water on the anode material of a lithium ion battery, and is complex in process and not beneficial to large-scale production.
Disclosure of Invention
The invention aims to provide a method for modifying a battery positive electrode material by using a phosphorus-containing organic substance in a non-aqueous system to reduce the alkalinity of the battery positive electrode material.
The invention provides a method for reducing alkalinity of a positive electrode material by using a phosphorus-containing organic matter, which is realized by obtaining the positive electrode material with the surface coated with lithium phosphate, and can be a scheme I or a scheme II as follows:
the first scheme is as follows: dispersing a battery positive electrode material and a phosphorus-containing organic matter into an organic solvent, stirring for a period of time, evaporating to dryness, and calcining a product at high temperature to obtain the battery positive electrode material with the surface coated with lithium phosphate;
scheme II: dispersing a battery positive electrode material, hexachlorotriphosphazene and a polymer monomer B into an organic solvent, reacting under the action of an alkaline reagent to obtain a polyphosphazene-coated battery positive electrode material, and calcining the polyphosphazene-coated battery positive electrode material at a high temperature to obtain the battery positive electrode material with the surface coated with lithium phosphate.
According to the present invention, the battery cathode material in both aspects may be a lithium ion battery cathode material, preferably at least one selected from lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel manganate, lithium nickel cobalt aluminate, more preferably lithium nickel cobalt manganate, such as 532 material (LiNi)0.5Co0.3Mn0.2O2) 622 materials (LiNi)0.6Co0.2Mn0.2O2) And 811 material (LiNi)0.8Co0.1Mn0.1O2)。
According to the invention, the concentration of the battery anode material in the organic solvent in the two schemes can be 0.01 g/L-500 g/L, preferably (0.1-500) g/L, more preferably (1-500) g/L, such as 2g/L, 10g/L, 20g/L, 30g/L and 400 g/L.
According to the present invention, the organic solvent in both embodiments is a non-aqueous solvent, including but not limited to methanol, ethanol, propanol, butanol, acetonitrile, acetone, N-dimethylformamide, thionyl chloride, dichloromethane, pyridine, diethyl ether, cyclohexane, hexane, octane, pentane, ethyl acetate, cyclohexanone, methylcyclohexanone, N-methylpyrrolidone, preferably any one or more of methanol, ethanol, propanol, butanol.
According to the invention, the high-temperature calcination temperatures described in both variants can be from 500 ℃ to 1000 ℃, preferably from 700 ℃ to 900 ℃, for example 750 ℃, 800 ℃, 820 ℃.
According to the invention, the time of the high-temperature calcination in the two schemes can be 1-20 h, preferably 1-10 h, more preferably 1-5 h, for example 2 h.
Preferably, the high temperature calcination in both schemes is carried out in an oxidizing atmosphere, such as an oxygen atmosphere.
According to the invention, the phosphorus-containing organic substance in the first embodiment is an organic substance containing a phosphorus element, and includes, for example, any one or more selected from the following: organic phosphoric acid compounds, such as phytic acid; phosphoric ester compounds such as dimethyl phosphate, diethyl phosphate, trimethyl phosphate, triethyl phosphate, dodecyl phosphoric acid; phosphite compounds such as dimethyl phosphite, diethyl phosphite, trimethyl phosphite, triethyl phosphite; phosphonate compounds such as dodecylphosphonic acid, tetradecylphosphonic acid, and the like; phosphazene compounds, such as hexachlorotriphosphazene; or other phosphorus-containing organic compounds, for example pyrophosphoryl chloride, tricyclohexylphosphorus, methylpyridinophosphonium, 1, 2-bis (dichlorophosphoryl) ethane, 1-propylphosphoric anhydride, acetyltriphenylphosphonium chloride, 1-propylphosphorus dichloride, hexamethylphosphoramidite, di-tert-butylmethylphosphorus, 1, 2-bis (diphenylphosphoromethyl) benzene, (formylmethyl) triphenylphosphonium chloride, diphenyllithium phosphide, 1, 3-bis (diphenylphosphoalkyl) propane, dimethylphosphoroamine chloride, bis (diethylamino) phosphonium chloride, phenylphosphoryl dichloride, 1-propylphosphoric anhydride, triisopropylphosphonium, phenylphosphoryl dichloride, ethylphosphoryl dichloride, (4-chlorobenzyl) triphenylphosphonium chloride, tris (trimethylsilyl) phosphonium, 1, 2-bis (dimethoxyphosphoryl) benzene, bis (dimethylamino) phosphoryl chloride, diethylphosphorous oxychloride, (tert-butoxycarbonylmethyl) triphenylphosphonium bromide, diphenylphosphoramide, (1-nonyl) triphenylphosphonium bromide, phenylphosphorus dichloride, triisopropylphosphonium, dichloromethylphosphorus, 1-propylphosphoric anhydride, (9-fluorenyl) triphenylphosphonium bromide, phenylphosphorus dichloride, tetradecyltributylphosphonium chloride, tributyltetradecylphosphonium chloride, 4-ethylphenylphosphoroso-diol, bis (3, 5-dimethylphenyl) phosphonium, phenylphosphorus diamide, 1, 2-bis (diethylphosphonium) ethane, diphenylphosphorus lithium, 1, 3-bis (diphenylphosphoryl) propane, bis (2,4, 6-trimethylphenyl) phosphonium chloride, dimethylphosphorus amine chloride, bis (diethylamino) chlorophosphorus, 1, 3-bis (dicyclohexylphosphonium) propane, tris (trimethylsilyl) phosphonium chloride, phosphoenolpyruvate, diethylthiophosphoryl chloride, methoxycarbonylmethylenetriphenylphosphorane, tricyclohexylphosphorus, bis (dichlorophosphasphoryl) methane, 2- (triphenylphosphoranylidene) succinic anhydride, tetrabutylphosphorus methanesulfonate, 2-chlorophenylphosphorodiamidate, 2,2, 2-trimethoxy-4, 5-dimethyl-1, 3, 2-dioxaphospholene.
Preferably, the phosphorus-containing organic compound in the first embodiment is selected from any one or more of organic phosphoric acid compounds, phosphoric acid ester compounds and phosphazene compounds.
As an example, the phosphorus-containing organic substance in the first embodiment may be any one or more of phytic acid, trimethyl phosphate, and hexachlorotriphosphazene.
According to the invention, in the first embodiment, the mass ratio of the battery cathode material to the phosphorus-containing organic substance may be 1 (0.05-1), preferably 1 (0.1-0.5), such as 1:0.15, 1:0.2, 1: 0.3.
According to the invention, in the first embodiment, the stirring time may be 0.5 to 100 hours, preferably 0.5 to 10 hours, more preferably 0.5 to 5 hours, for example 2 hours.
According to the invention, the temperature for evaporating to dryness in the first embodiment may be 20 ℃ to 200 ℃, preferably 50 ℃ to 100 ℃, for example 80 ℃.
According to the invention, the polymer monomer B in the second scheme is C containing at least two phenolic hydroxyl groups6-12The aromatic ring compound may be any one or more of 4,4 '-dihydroxydiphenyl sulfone, 4, 4' -dihydroxydiphenyl ether, and phloroglucinol, for example.
According to the invention, the mass ratio of the battery cathode material to the hexachlorotriphosphazene and the polymer monomer B in the second embodiment can be (1-50): 1 (1-5), preferably (5-30): 1 (1-3), such as 6.7:1:2, 13.3:1:2, and 20:1: 2.
According to the present invention, the alkaline agent in scheme two may be an organic amine compound including, for example, any one or more selected from the group consisting of: methylamine, ethylamine, propylamine, isopropylamine, dimethylamine, diethylamine, diisopropylamine, triethylamine; triethylamine is preferred.
According to the invention, the volume ratio of the alkaline agent to the organic solvent in the second embodiment may be 1 (10-500), preferably 1 (50-200), for example 1: 100.
According to the invention, the reaction time in the second scheme is 0.5-100 h, preferably 1-10 h, for example 6 h.
According to the invention, the reaction temperature in the second embodiment is 20 ℃ to 200 ℃, preferably 20 ℃ to 100 ℃, more preferably 20 ℃ to 50 ℃, for example 30 ℃.
The invention also provides a positive electrode material, which is obtained by the method and is coated with lithium phosphate on the surface.
The invention also provides a high-energy storage lithium device, which takes the positive electrode material with the surface coated with lithium phosphate as an electrode.
According to the present invention, the high energy type lithium storage device is a lithium ion battery or a lithium battery.
The invention has the beneficial effects that:
the battery anode material is dispersed into an organic solvent containing phosphorus organic matter, the phosphorus organic matter is uniformly distributed on the surface of the battery anode material through liquid phase mixing or in-situ polymerization, and during subsequent calcination treatment, phosphorus element reacts with residual lithium on the surface at high temperature to generate lithium phosphate in situ, so that the battery anode material with the surface coated with the lithium phosphate is obtained. Because the organic phosphorus source and the organic solvent are adopted, the whole treatment process has no adverse effect on the battery anode material; residual lithium on the surface of the battery anode material obtained after treatment is consumed, and alkalinity is reduced; the product surface is coated with phosphorusLithium oxide and lithium phosphate are lithium ion fast conductors, and the lithium ion conductivity is high, so that the electrochemical performance of the battery anode material is not adversely affected; lithium phosphate has good stability in air and does not react with CO2The reaction, the water absorption performance is far lower than that of LiOH, and the lithium phosphate is coated on the surface of the battery anode material, so that the reaction of the battery anode material with water vapor, carbon dioxide and the like in the air is reduced, and the stability of the battery anode material in the air is improved; because the water absorption of the lithium phosphate is poor, the treated battery anode material has less moisture brought in the battery assembling process, the decomposition of the electrolyte is favorably slowed down, and the electrochemical performance of the battery is improved.
The invention utilizes phosphorus element in organic compound, constructs lithium phosphate surface coating layer in non-aqueous system, completely avoids adverse effect of water on battery anode material, consumes residual lithium on surface while maintaining structural stability of battery anode material, and reduces alkalinity; a uniform lithium phosphate coating layer is constructed on the surface of the battery anode material, so that the stability and the electrochemical performance of the battery anode material in the air are improved.
The phosphorus-containing organic compound utilized by the invention has wide source and low cost; the liquid phase method is adopted, the condition is mild, the process is simple, and the industrial production is easy to realize.
Drawings
FIG. 1 shows LiNi before and after coating treatment in example 10.6Co0.2Mn0.2O2SEM image of (a);
FIG. 2 shows LiNi after coating treatment in example 10.6Co0.2Mn0.2O2EDS analysis images of;
FIG. 3 shows LiNi before and after the coating treatment in example 10.6Co0.2Mn0.2O2XRD spectrum of (1);
FIG. 4 shows LiNi before and after the coating treatment in example 20.6Co0.2Mn0.2O2A charge-discharge curve chart at 3.0-4.5V;
FIG. 5 shows LiNi before and after coating treatment in example 20.6Co0.2Mn0.2O2A cycle performance plot at 0.2C magnification;
FIG. 6 isExample 5 LiNi before and after coating treatment0.6Co0.2Mn0.2O2Cycle performance plot at 0.2C rate after 180 days of air exposure;
FIG. 7 is a LiNi of different poly (cyclotriphosphazene-co-4, 4' -dihydroxydiphenylsulfone) coating thicknesses prior to calcination in example 60.6Co0.2Mn0.2O2A TEM image of (a);
FIG. 8 is LiNi before calcination in example 60.6Co0.2Mn0.2O2EDS image of (a);
FIG. 9 is LiNi after calcination in example 60.6Co0.2Mn0.2O2A TEM image of (a);
FIG. 10 is LiNi after calcination in example 60.6Co0.2Mn0.2O2EDS image of (a);
FIG. 11 shows LiNi before and after the coating treatment in example 70.6Co0.2Mn0.2O2A cycle performance diagram at 0.2C magnification;
FIG. 12 shows LiNi before and after the coating treatment in example 80.6Co0.2Mn0.2O2Cycle performance at 0.2C rate.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
Example 1
Firstly, preparation of lithium phosphate coated LiNi0.6Co0.2Mn0.2O2(abbreviation 622 material)
Dispersing 1g of 622 material in 100ml of methanol, adding 0.15g of hexachlorotriphosphazene, stirring for 2h, evaporating in a water bath at 80 ℃ to dryness, and calcining the product in a tube furnace at 750 ℃ for 2h in an oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate.
Secondly, performing structural and morphological characterization on 622 material before and after coating treatment
Scanning electron microscope images (SEM images) of the 622 material before and after the coating treatment are shown in fig. 1. The SEM images showed no significant change in material morphology before and after treatment. EDS analysis of the surface of the coated material is shown in FIG. 2, and FIG. 2 shows that phosphorus is uniformly distributed on the surface of the material. Fig. 3 shows that the diffraction peak of 622 material did not change significantly before and after the coating process, indicating that the process did not adversely affect the structure of the material. Since the amount of lithium phosphate was small, the peak of lithium phosphate could not be detected.
Example 2
Firstly, preparing 622 material coated by lithium phosphate
Dispersing 1g of 622 material in 100ml of methanol, adding 0.15g of hexachlorotriphosphazene, stirring for 2h, evaporating in a water bath at 80 ℃ to dryness, and calcining the product in a tube furnace at 750 ℃ for 2h in an oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate.
Two, assemble button cell
Respectively taking the 622 material after coating treatment and the 622 material without coating treatment as electrode materials, pulping the electrode materials according to the proportion of carbon black to PVDF (polyvinylidene fluoride) of 8:1:1, coating the electrode materials on an aluminum foil to be used as a positive electrode, taking lithium metal as a negative electrode and taking 1M electrolyte as LiPF6The method comprises the steps of assembling a button cell with an electrolyte, wherein the electrolyte solvent is EC, DEC and DMC (1: 1: 1), performing an electrochemical cycle test of 0.2C (theoretical specific capacity of 200mAh/g) within a voltage range of 3.0-4.5V, wherein the test temperature is 25 ℃, the charge-discharge curve is shown in figure 4, and figure 4 shows that the charge-discharge curve of a 622 material coated with lithium phosphate on the surface has no obvious difference with the charge-discharge curve of a 622 material not coated with lithium phosphate, and the specific capacity is not reduced; fig. 5 is a plot of their respective cycle performance data, showing enhanced cycling stability of the cell assembled from the coated material. The method of the invention improves the electrochemical stability of the anode materialAnd (4) sex.
Example 3
Dispersing 1g of 622 material into 100ml of methanol, respectively adding hexachlorotriphosphazene with the mass percentage of 10%, 20% and 50% of 622 material, stirring for 2h, placing in a water bath at 80 ℃ for drying by distillation, placing the product in a tubular furnace, and calcining for 2h at 750 ℃ under the oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate.
The obtained materials were dispersed in water at a ratio of 1:10, respectively, ultrasonically stirred, allowed to stand for 30min, and tested for pH, with the results shown in table 1. As can be seen from table 1, the coating method of the present invention can effectively lower the pH of 622 material due to the conversion of residual lithium on the surface to lithium phosphate.
TABLE 1 pH of 622 material obtained after addition of varying amounts of hexachlorotriphosphazene
| Uncoated treated |
10％ | 20％ | 50％ | |
| pH | 11.15 | 10.82 | 10.44 | 10.08 |
Example 4
Dispersing 1g of 622 material into 100ml of methanol, respectively adding hexachlorotriphosphazene with the mass percentage of 10%, 20% and 50% of 622 material, stirring for 2h, placing in a water bath at 80 ℃ for drying by distillation, placing the product in a tubular furnace, and calcining for 2h at 750 ℃ under the oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate. Placing the obtained material in air, standing for 180 days, dissolving the material in water at a ratio of 1:10, ultrasonic stirring, standing for 30min, and testing pH. As shown in table 2, the 622 material coated with lithium phosphate obtained by the method of the present invention can still effectively reduce the pH value of the material after long-term storage. Indicating that the existence of the lithium phosphate coating layer effectively prevents the 622 material from further reacting with water vapor and carbon dioxide in the air.
TABLE 2 pH of 622 material after 180 days storage
| Uncoated treated |
10％ | 20％ | 50％ | |
| pH | 11.31 | 10.94 | 10.47 | 10.11 |
Example 5
Dispersing 1g of 622 material in 100ml of methanol, adding 0.15g of hexachlorotriphosphazene, stirring for 2h, evaporating in a water bath at 80 ℃ to dryness, and calcining the product in a tube furnace at 750 ℃ for 2h in an oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate. The coated 622 material and the untreated 622 material were exposed to air for 180 days, and the button cell was assembled by the same method as in example 2, and subjected to electrochemical performance test under the same conditions as in example 2. As shown in fig. 6, the 622 material coated according to the method of the present invention can improve the electrochemical stability of the material after long-term storage.
Example 6
1g, 2g and 3g 622 of the material are respectively dispersed in 100ml of methanol, 0.15g hexachlorotriphosphazene and 0.3g 4, 4' -dihydroxydiphenylsulfone are added, the mixture is stirred for 0.5h, 1ml triethylamine is added, and the mixture is reacted for 6h at 30 ℃. The product is a 622 material coated with poly (cyclotriphosphazene-co-4, 4' -dihydroxydiphenylsulfone). The transmission electron micrograph is shown in FIG. 7, and from FIG. 7, it can be seen that 622 material with different poly (cyclotriphosphazene-co-4, 4' -dihydroxydiphenylsulfone) coating thicknesses can be obtained by adjusting the amount of 622 material: the thicknesses of the poly (cyclotriphosphazene-co-4, 4' -dihydroxydiphenylsulfone) coatings were 60nm (FIG. 7(c)), 20nm (FIG. 7(b)), and 3nm (FIG. 7(a)), respectively, in the materials obtained using 1g, 2g, and 3g of uncoated 622 material. EDS analysis (as shown in figure 8) showed that the poly (cyclotriphosphazene-co-4, 4' -dihydroxydiphenylsulfone) coating on 622 material was achieved.
The 622 material coated with the poly (cyclotriphosphazene-co-4, 4 '-dihydroxydiphenyl sulfone) is calcined for 2h at 800 ℃ in an oxygen atmosphere, and after calcination, the poly (cyclotriphosphazene-co-4, 4' -dihydroxydiphenyl sulfone) coating disappears (as shown in figure 9), so that the 622 material coated with the lithium phosphate on the surface is generated. EDS analysis (fig. 10) showed that the phosphorus element was uniformly distributed on the surface of the 622 material surface-coated with lithium phosphate.
The in-situ polymerization method can achieve the same treatment effect as liquid phase mixing, and can realize the construction of a uniform and controllable phosphorus-containing organic matter coating layer. The scheme is beneficial to building a model system and further researching a related mechanism.
Example 7
Dispersing 0.2g622 material into 100ml ethanol, adding 0.05ml trimethyl phosphate, stirring for 2h, placing in 80 deg.C water bath, evaporating to dryness, placing the product in a tube furnace, calcining at 750 deg.C for 2h under oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate. The button cell was assembled in the same manner as in example 2, and electrochemical performance test was performed under the same conditions as in example 2, and as shown in fig. 11, the cycle performance of the product was found to be greatly improved. The first technical proposal can effectively improve the stability of the anode material.
Example 8
Dispersing 40g622 material into 100ml ethanol, adding 3ml phytic acid, stirring for 2h, placing in 80 ℃ water bath for evaporation, placing the product in a tube furnace, calcining for 2h at 820 ℃ under oxygen atmosphere. Naturally cooling to obtain 622 material with the surface coated with lithium phosphate. The button cell was assembled in the same manner as in example 2, and electrochemical performance test was performed under the same conditions as in example 2, and it was found that the cycle performance of the product was greatly improved as shown in fig. 12.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The method for reducing the alkalinity of the cathode material by using the phosphorus-containing organic matter is characterized in that the method is realized by obtaining the cathode material with the surface coated with lithium phosphate, and the method adopts the following scheme I:
the first scheme is as follows: dispersing a battery positive electrode material and a phosphorus-containing organic matter into an organic solvent, stirring for a period of time, evaporating to dryness, and calcining a product at high temperature to obtain the battery positive electrode material with the surface coated with lithium phosphate;
the phosphorus-containing organic matter is hexachlorotriphosphazene;
the battery anode material is selected from at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel manganate, lithium nickel cobalt manganate and lithium nickel cobalt aluminate;
the concentration of the battery anode material in the organic solvent is 0.01-500 g/L;
the organic solvent is selected from any one or more of methanol, ethanol, propanol and butanol;
the mass ratio of the battery anode material to the phosphorus-containing organic matter is 1 (0.1-0.5);
the high-temperature calcination temperature is 700-750 ℃;
the high-temperature calcination time is 2 h;
the high-temperature calcination is carried out in an oxygen atmosphere;
the stirring time is 0.5-100 h;
the temperature for evaporating to dryness is 20-200 ℃.
2. The method of claim 1, wherein the battery positive electrode material is lithium nickel cobalt manganese oxide.
3. The method according to claim 1 or 2, wherein the battery positive electrode material is LiNi0.6Co0.2Mn0.2O2。
4. The method according to claim 1 or 2, wherein the concentration of the battery positive electrode material in the organic solvent is (0.1 to 500) g/L.
5. The method according to claim 1 or 2, wherein the stirring time is 0.5 to 10 hours;
the temperature for evaporating to dryness is 50-100 ℃.
6. A positive electrode material, characterized in that the positive electrode material is a surface-coated lithium phosphate positive electrode material obtained by the method according to any one of claims 1 to 5.
7. A high energy type energy storage lithium device, which uses the positive electrode material with the surface coated with lithium phosphate obtained by the method of any one of claims 1 to 5 as an electrode.
8. The high energy type energy storage lithium device according to claim 7, wherein the high energy type lithium storage device is a lithium ion battery or a lithium battery.
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| CN106571446A (en) * | 2015-10-07 | 2017-04-19 | 株式会社Lg化学 | Positive electrode active material, manufacturing method of the same, and lithium secondary battery |
| CN107248573A (en) * | 2017-06-26 | 2017-10-13 | 浙江工业大学 | Polyphosphazene is combined the preparation method of carbon composite electrode material for the molybdenum disulfide of carbon source |
| CN108232182A (en) * | 2016-12-13 | 2018-06-29 | 天津国安盟固利新材料科技股份有限公司 | A kind of modified nickel-cobalt lithium manganate cathode material and preparation method thereof |
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| CN108232182A (en) * | 2016-12-13 | 2018-06-29 | 天津国安盟固利新材料科技股份有限公司 | A kind of modified nickel-cobalt lithium manganate cathode material and preparation method thereof |
| CN107248573A (en) * | 2017-06-26 | 2017-10-13 | 浙江工业大学 | Polyphosphazene is combined the preparation method of carbon composite electrode material for the molybdenum disulfide of carbon source |
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