A kind of trimanganese tetraoxide for lithium ion battery and its preparation method

Abstract

The present application relates to the technical field of metal oxides, in particular to a kind of trimanganese tetraoxide for lithium ion battery and preparation method thereof.The technology is by introducing citric acid-p-phenylenediamine-glutamic acid diacetic acid ammonium salt and citric acid-trioxa-tridecanediamine-glutamic acid diacetic acid ammonium salt Double ligand synergistic complex system, under the condition of controlling pH 6 and temperature 60 DEG C, using subsection type dropwise adding ammonium bicarbonate to carry out coprecipitation.Precipitate is washed strictly, pre-baking and air calcination in nitrogen atmosphere, finally obtain high spherical degree, high tap density, the particle size distribution of trimanganese tetraoxide dense spherical particle is narrow.The technology solves the bottleneck such as wide particle size distribution, poor spherical degree, ion pollution and densification deficiency in traditional process, significantly improves the controllability of nucleation and crystallization and secondary agglomeration densification of material, reduces coating defect and material dispersion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal oxides, and particularly relates to a trimanganese tetraoxide for a lithium ion battery and a preparation method thereof. BACKGROUND

[0002] With the rapid development of new energy automobile industry and the increasing demand of energy storage system, the performance requirements of lithium ion battery as the main electrochemical energy storage device are increasingly stringent. Trimanganese tetraoxide (Mn3O4) as an important battery material precursor plays a key role in the preparation of lithium manganate and other positive electrode materials. Its physical and chemical properties directly affect the electrochemical performance, cycle stability and safety characteristics of the final battery material.

[0003] The traditional preparation methods of trimanganese tetraoxide mainly include solid phase method, coprecipitation method, sol-gel method, etc. Among them, the coprecipitation method is widely used because of its relatively simple process and low cost. However, there are many technical bottlenecks in the existing technology, which seriously restricts the industrial production of high-performance trimanganese tetraoxide.

[0004] Firstly, the morphology control is difficult, which is the main challenge currently faced. The ideal trimanganese tetraoxide particles should have high sphericity, uniform particle size distribution and dense internal structure to ensure good flowability, high tap density and excellent compaction performance. However, the nucleation and growth process in the traditional precipitation process is difficult to accurately control, and irregular morphology, internal loose and porous particles are easily formed, resulting in low tap density, wide particle size distribution, poor sphericity and other problems.

[0005] Secondly, the crystal face directional growth regulation technology is not mature. The crystal structure characteristics of trimanganese tetraoxide determine that the surface energy of different crystal faces is significantly different, and under the condition of disordered nucleation, anisotropic growth is easily formed, producing rod-shaped, sheet-shaped and other non-spherical morphologies. Lack of effective crystal face regulator and directional induction mechanism, it is difficult to realize the equiaxed crystal growth and the dense aggregation of secondary particles.

[0006] Thirdly, the ion pollution control problem is prominent. In the traditional preparation process, precipitants and complexing agents containing alkali metals such as sodium and potassium are often used. These alkali metal ions are difficult to completely remove in the subsequent washing process, forming solid solution or interface segregation, which seriously affects the electrochemical stability of the material. Especially sodium ions, which will compete with lithium ions for insertion sites during the operation of lithium ion batteries, resulting in capacity attenuation and cycle performance deterioration.

[0007] In addition, the precipitation kinetics control precision is insufficient. The existing precipitation process mostly adopts the way of single precipitant one-time addition, the nucleation rate and the growth rate are difficult to independently control, and it is easy to appear fine particles and loose agglomeration caused by instantaneous nucleation, or coarse particles and uneven distribution caused by insufficient nucleation. Lack of staged and gradual precipitation kinetics design, it is impossible to establish the ideal "slow nucleation-dense growth-ordered agglomeration" reaction window.

[0008] Finally, the post-processing process is not optimized enough. The washing end point control, drying condition selection, calcination atmosphere design and other post-processing links have a decisive influence on the quality of the final product, but the existing technology often ignores the accurate control of these detailed parameters. Insufficient washing leads to the residual of soluble impurities, and improper calcination conditions cause the increase of internal pores or surface defects of the particles, which finally affects the tap density, flowability and electrochemical performance of the material.

[0009] The above technical defects are manifested in industrial application as follows: the prepared trimanganese tetraoxide has low tap density, poor sphericity, wide particle size distribution and serious tail drag, and it is easy to appear rheological instability, high coating defect rate and poor compaction uniformity in the slurry preparation and coating process, which seriously affects the yield and consistency of battery manufacturing, and becomes an important bottleneck restricting the industrialization of high-performance lithium-ion batteries. SUMMARY

[0010] Therefore, the purpose of the present application is to provide a trimanganese tetraoxide for lithium-ion batteries and a preparation method thereof, so as to realize the preparation of dense spherical particles with high tap density, high sphericity and narrow particle size distribution by precise crystal face orientation control and staged precipitation kinetics design, and to meet the strict requirements of high tap density lithium manganate mass production process on raw material quality.

[0011] Based on the above purpose, the present application provides a trimanganese tetraoxide for lithium-ion batteries, which is prepared from manganese sulfate monohydrate in a double-ligand system containing citric acid-p-phenylenediamine-ammonium glutamate diacetate and citric acid-trioxatridecanediamine-ammonium glutamate diacetate, under the conditions of pH 6 and 60℃, by two-stage equal-volume addition of 1mol / L ammonium bicarbonate aqueous solution for precipitation, washing, drying, and then pre-calcination in nitrogen atmosphere and calcination in air atmosphere; wherein the ammonium bicarbonate aqueous solution is subjected to maturation treatment after two-stage equal-volume addition, and the washing is carried out until the conductivity of the filtrate is ≤50μS / cm.

[0012] Further, the citric acid-p-phenylenediamine-ammonium glutamate diacetate is synthesized from p-phenylenediamine and di-tert-butyl carbonate to obtain a single-end protected body, then grafted with citric acid to obtain a citric acid-p-phenylenediamine intermediate, then deprotected from the p-phenylenediamine end, grafted with glutamic acid diacetate, and purified by dialysis.

[0013] Preferably, the weight ratio of the p-phenylenediamine, di-tert-butyl carbonate, citric acid and glutamic acid diacetate is 10:10:10:27.

[0014] Further, the citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is synthesized from 4,7,10-trioxa-1,13-tridecanediamine and di-tert-butyl carbonate to form a single end protection body, then grafted with citric acid to obtain a citric acid-trioxatridecanediamine intermediate, and then the trioxatridecanediamine end is deprotected and grafted with glutamic acid diacetate, and then purified by dialysis.

[0015] Preferably, the weight ratio of the 4,7,10-trioxa-1,13-tridecanediamine, di-tert-butyl carbonate, citric acid and glutamic acid diacetate is 12:6:10:27.

[0016] Preferably, the citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt is 6.25-7.78 parts by mass and the citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is 6.88-8.89 parts by mass based on 100 parts by mass of manganese sulfate monohydrate.

[0017] Preferably, the amount-of-substance ratio of the ammonium bicarbonate to the manganese sulfate monohydrate is 0.47-0.53:1.

[0018] Preferably, the pre-baking temperature in a nitrogen atmosphere is 500℃, and the holding time is 1.5-3.0h; the baking temperature in an air atmosphere is 650℃, and the holding time is 3-5h.

[0019] Preferably, the particle size distribution of the trimanganese tetraoxide for lithium ion batteries has a D10 of 5-6μm, a D50 of 9-10μm, and a D90 of 14-15μm; the tap density is 3.15-3.30g / cm 3 ; and the sphericity is 0.94-0.95.

[0020] Preferably, the glutamic acid diacetate is obtained by converting a glutamic acid diacetate tetrasodium aqueous solution through a cation exchange resin column.

[0021] Preferably, the cation exchange resin is DOWEX 50WX8, and the sample injection flow rate is 80-120mL / h.

[0022] Further, the application also provides a preparation method of the trimanganese tetraoxide for lithium ion batteries, comprising the following steps: dissolving manganese sulfate monohydrate in deionized water to obtain a solution, adding citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt and citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt, adjusting the pH to 6 with ammonia water after stirring for 30 min, and keeping the temperature at 60 DEG C; adding ammonium bicarbonate aqueous solution in two equal volumes, the first stage is added for 40-50 min, matured for 10-20 min, the second stage is added for 10-20 min, and matured again for 25-40 min, filtered, washed with deionized water until the conductivity of the filtrate is less than or equal to 50 mu S / cm, dried at 80 DEG C for 8 h, and then sequentially pre-baked in a nitrogen atmosphere and baked in an air atmosphere to obtain the trimanganese tetraoxide for lithium ion batteries.

[0023] The application realizes a plurality of significant technical advantages by constructing a citric acid-p-phenylenediamine-glutamic acid diacetate and citric acid-trioxatridecanediamine-glutamic acid diacetate double-ligand synergistic complexing system, combining a segmented ammonium bicarbonate precipitation and a two-stage baking process.

[0024] The crystal face directional growth is precisely controlled. In the double-ligand system, the rigid aromatic fragment containing p-phenylenediamine provides a stable pi-pi stacking effect to adjust the surface energy of a specific crystal face; the flexible ether segment containing trioxatridecanediamine realizes dynamic coordination adjustment through multi-point chelation. The multi-dentate coordination network formed by the two types of ligands and glutamic acid diacetate selectively adsorbs on the high-energy crystal face of the trimanganese tetraoxide crystal under the condition of pH 6, effectively inhibits anisotropic growth, induces the formation of equiaxed crystals, and realizes the improvement of sphericity.

[0025] The secondary particle dense agglomeration mechanism is optimized. Through the segmented precipitant addition strategy, the first stage slowly adds ammonium bicarbonate to establish uniform and fine crystal nucleus distribution, and the short-time maturation stabilizes the primary phase; the second stage quickly supplements to promote the dense growth of the crystal nucleus, and the extended maturation time drives the secondary agglomeration reconstruction. The organic coordination bridge formed by the double-ligand molecules on the particle surface guides the ordered arrangement and dense accumulation of the crystal grains, and significantly improves the tap density.

[0026] Ion pollution is effectively eliminated. The glutamic acid diacetate tetrasodium is pretreated into an acid type by using ion exchange resin to eliminate the introduction of sodium ions from the source; ammonium bicarbonate is selected instead of sodium bicarbonate as a precipitant to avoid additional alkali metal pollution; the washing endpoint is strictly controlled to less than or equal to 50 mu S / cm to ensure that the soluble impurities are fully removed. This series of measures completely solves the ion pollution problem in the traditional process.

[0027] The particle size distribution is narrowed and the uniformity is improved. The double-ligand synergistic complexing inhibits a large number of instantaneous nucleation, the segmented precipitation realizes the time and space separation of nucleation and growth, effectively compresses the particle size distribution range, and controls D10-D90 in a narrow range, eliminating the coarse particle tail phenomenon in the traditional process.

[0028] The structure is improved by optimizing the calcination process. The mild decomposition of organic ligands and ammonium salts in the nitrogen pre-calcination stage avoids internal pores caused by violent gas release; the air atmosphere calcination completes the removal of sulfate and lattice perfection, ensuring the internal density and surface integrity of the particles.

[0029] The process applicability and stability are significantly improved. The prepared trimanganese tetraoxide exhibits excellent rheological stability during slurry preparation, and the coating defect rate is reduced to 7%-8%; the pressing piece density uniformity is greatly improved, and the dispersion coefficient is controlled at 1.5%-2.3%, which is much better than the traditional process level of 4.0%-6.5%.

[0030] The industrial application value is outstanding. The trimanganese tetraoxide prepared by the present application has high tap density, excellent sphericity, uniform distribution and low impurity content, fully meeting the strict requirements of high-pressure density lithium manganate production line, providing reliable raw material guarantee for improving battery manufacturing yield and product consistency, and having important industrialization popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present application or prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below.

[0032] Figure 1 The infrared spectra of citric acid-p-phenylenediamine-ammonium glutamate diacetate and citric acid-trioxa-tridecanediamine-ammonium glutamate diacetate in Example 2 of the present application;

[0033] Figure 2 The viscosity-shear rate curve of the slurry prepared by the trimanganese tetraoxide in Example 1-3 of the present application;

[0034] Figure 3 The viscosity-shear rate curve of the slurry prepared by the trimanganese tetraoxide in Example 2 and Comparative Examples 1-7 of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application will be further described in detail below in combination with specific embodiments.

[0036] Example 1:

[0037] (1) Take 73.6 g of tetrasodium glutamate diacetate and dissolve it in 500 mL of deionized water to prepare a tetrasodium glutamate diacetate solution. Load 750 mL of cation exchange resin DOWEX 50WX8 into an ion exchange column, wash it with 2 mol / L hydrochloric acid until the pH of the effluent is less than 2.0, and then wash it with deionized water until the conductivity of the effluent is less than 10 μS / cm. Pass the tetrasodium glutamate diacetate solution through the ion exchange column at a flow rate of 80 mL / h, collect the effluent until the pH stabilizes at 2.2, and concentrate the effluent under reduced pressure to 500 mL to obtain a glutamate diacetate solution;

[0038] (2) Take 10 g of p-phenylenediamine and add it to 100 mL of anhydrous ethanol in an ice bath. Slowly add 10 g of di-tert-butyl carbonate and stir for 2 h to obtain a single-tert-butoxycarbonyl-protected p-phenylenediamine ethanol solution. Take 10 g of citric acid and add it to 120 mL of deionized water in an ice bath. Then, sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with a hydrochloric acid aqueous solution (concentration 1 mol / L). Stir for 30 min to activate, slowly add the single-tert-butoxycarbonyl-protected p-phenylenediamine ethanol solution, and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 10 h to obtain a citric acid-p-phenylenediamine intermediate mixture solution;

[0039] (3) Take 20 mL of a hydrochloric acid anhydrous ethanol solution (concentration 4 mol / L) and add it to the citric acid-p-phenylenediamine intermediate mixture solution prepared in step (2). Stir for 1 h to remove the tert-butoxycarbonyl protection, add 200 mL of deionized water, and remove the ethanol under reduced pressure. Adjust the pH to 5 with ammonia water (concentration 2 mol / L) to obtain a citric acid-p-phenylenediamine free amine salt solution;

[0040] (4) Take 250 mL of the glutamate diacetate solution and place it in an ice bath. Sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with a hydrochloric acid aqueous solution (concentration 1 mol / L). Stir for 30 min to activate, slowly add the citric acid-p-phenylenediamine free amine salt solution prepared in step (3), and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 14 h. After the reaction is completed, adjust the pH to 3 with a hydrochloric acid aqueous solution (concentration 1 mol / L). After standing for 1 h, filter and discard the insoluble material. Take the filtrate, load it into a molecular weight cutoff value 500 Da dialysis bag, dialyze it in deionized water for 48 h, replace the deionized water every 8 h until the conductivity is less than 100 μS / cm, adjust the pH to 7 with ammonia water (concentration 2 mol / L), and freeze-dry to obtain a citric acid-p-phenylenediamine-glutamate diacetate ammonium salt;

[0041] (5) Take 12 g of 4,7,10-trioxa-1,13-tridecanediamine and add to 100 mL of anhydrous ethanol in an ice bath, then slowly add 6 g of di-tert-butyl carbonate and stir for 2 h to obtain a single-terminated tert-butoxycarbonyl-protected trioxa-tridecanediamine ethanol solution. Take 10 g of citric acid and add to 120 mL of deionized water in an ice bath, then sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 min to activate, then slowly add the single-terminated tert-butoxycarbonyl-protected trioxa-tridecanediamine ethanol solution, and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 10 h to obtain a citric acid-trioxa-tridecanediamine intermediate mixture;

[0042] (6) Take 20 mL of anhydrous ethanol hydrochloric acid solution (concentration 4 mol / L) and add to the citric acid-trioxa-tridecanediamine intermediate mixture prepared in step (5), and stir for 1 h to remove the tert-butoxycarbonyl protection. Add 200 mL of deionized water and remove the ethanol under reduced pressure, and adjust the pH to 5 with ammonia water (concentration 2 mol / L) to obtain a citric acid-trioxa-tridecanediamine free amine salt solution;

[0043] (7) Take 250 mL of glutamic acid diacetic acid solution and place in an ice bath, then sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 min to activate, then slowly add the citric acid-trioxa-tridecanediamine free amine salt solution prepared in step (6), and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 14 h, then adjust the pH to 3 with an aqueous hydrochloric acid solution (concentration 1 mol / L) after the reaction is complete. Let stand for 1 h, then filter and discard the insoluble material. Take the filtrate and load into a molecular weight cutoff value 500 Da dialysis bag in deionized water and dialyze for 48 h, replacing the deionized water every 8 h until the conductivity is less than 100 μS / cm. Adjust the pH to 7 with ammonia water (concentration 2 mol / L) and freeze-dry to obtain a citric acid-trioxa-tridecanediamine-glutamic acid diacetic acid ammonium salt;

[0044] (8) Take 160 g of manganese sulfate monohydrate, add deionized water to make up to a total volume of 1000 mL, stir to dissolve, and obtain a manganese sulfate solution. Take 10 g of citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt and 11 g of citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt, add them to the manganese sulfate solution, stir for 30 min, then adjust the pH to 6 with ammonia water (concentration 2 mol / L), heat to 60°C, and maintain the temperature. Add 250 mL of ammonium bicarbonate aqueous solution (concentration 1 mol / L) at a uniform speed of 50 min, maintain the temperature at 60°C, and stir for 10 min. Then add 250 mL of ammonium bicarbonate aqueous solution (concentration 1 mol / L) at a fast speed of 20 min, maintain the temperature at 60°C, and stir for 25 min. Filter the obtained slurry and wash with deionized water until the conductivity of the filtrate is less than 50 μS / cm. Take the wet filter cake and place it in a vacuum oven, dry at 80°C for 8 h, heat at 500°C for 1.5 h under a nitrogen atmosphere, and then heat at 650°C for 3 h under an air atmosphere to obtain manganese sesquioxide for lithium ion batteries.

[0045] Example 2:

[0046] (1) Take 73.6 g of tetrasodium glutamate diacetate and dissolve it in 500 mL of deionized water to prepare a tetrasodium glutamate diacetate solution. Load 750 mL of cation exchange resin DOWEX 50WX8 into an ion exchange column, wash with 2 mol / L hydrochloric acid until the pH of the effluent is less than 2.0, and then wash with deionized water until the conductivity of the effluent is less than 10 μS / cm. Pass the tetrasodium glutamate diacetate solution through the ion exchange column at a flow rate of 100 mL / h, collect the effluent until the pH stabilizes at 2.2, and concentrate the effluent under reduced pressure to 500 mL to obtain a glutamic acid diacetate solution.

[0047] (2) Take 10 g of p-phenylenediamine and add it to 100 mL of anhydrous ethanol in an ice bath. Then slowly add 10 g of di-tert-butyl carbonate dropwise and stir for 2 h to obtain a single-terminated tert-butyloxycarbonyl-protected p-phenylenediamine ethanol solution. Separately, take 10 g of citric acid and add it to 120 mL of deionized water in an ice bath. Then sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 min to activate, then slowly add the single-terminated tert-butyloxycarbonyl-protected p-phenylenediamine ethanol solution, and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 12 h to obtain a citric acid-p-phenylenediamine intermediate mixture.

[0048] (3) Take 20 mL of hydrochloric acid anhydrous ethanol solution (concentration 4 mol / L) and add it to the citric acid-p-phenylenediamine intermediate mixed solution prepared in step (2), stir for 1 h to remove the tert-butyloxycarbonyl protection, then add 200 mL of deionized water and remove the ethanol under reduced pressure, adjust the pH to 5 with ammonia water (concentration 2 mol / L) to obtain a citric acid-p-phenylenediamine free amine salt solution;

[0049] (4) Take 250 mL of glutamic acid diacetic acid solution and place it in an ice bath, then take 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide and add them in sequence, and adjust the pH to 5 with hydrochloric acid aqueous solution (concentration 1 mol / L), stir for 30 min for activation, slowly add the citric acid-p-phenylenediamine free amine salt solution prepared in step (3), and adjust the pH to 6 with ammonia water (concentration 2 mol / L), stir at room temperature for 16 h, after the reaction is completed, adjust the pH to 3 with hydrochloric acid aqueous solution (concentration 1 mol / L), stand for 1 h, then filter and discard the insoluble matter, take the filtrate and place it in a molecular weight cutoff value 500 Da dialysis bag in deionized water for dialysis for 48 h, replace the deionized water every 8 h until the conductivity is less than 100 μS / cm, adjust the pH to 7 with ammonia water (concentration 2 mol / L) and freeze-dry to obtain a citric acid-p-phenylenediamine-glutamic acid diacetic acid ammonium salt;

[0050] (5) Take 12 g of 4,7,10-trioxa-1,13-tridecanediamine and add it to 100 mL of anhydrous ethanol and place it in an ice bath, then slowly add 6 g of di-tert-butyl carbonate and stir for 2 h to obtain a single-end tert-butyloxycarbonyl-protected trioxa-tridecanediamine ethanol solution, take another 10 g of citric acid and add it to 120 mL of deionized water and place it in an ice bath, then take 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide and add them in sequence, and adjust the pH to 5 with hydrochloric acid aqueous solution (concentration 1 mol / L), stir for 30 min for activation, slowly add the single-end tert-butyloxycarbonyl-protected trioxa-tridecanediamine ethanol solution, and adjust the pH to 6 with ammonia water (concentration 2 mol / L), stir at room temperature for 12 h to obtain a citric acid-trioxa-tridecanediamine intermediate mixed solution;

[0051] (6) Take 20 mL of hydrochloric acid anhydrous ethanol solution (concentration 4 mol / L) and add it to the citric acid-trioxa-tridecanediamine intermediate mixed solution prepared in step (5), stir for 1 h to remove the tert-butyloxycarbonyl protection, then add 200 mL of deionized water and remove the ethanol under reduced pressure, adjust the pH to 5 with ammonia water (concentration 2 mol / L) to obtain a citric acid-trioxa-tridecanediamine free amine salt solution;

[0052] (7) Take 250 mL glutamic acid diacetic acid solution into ice bath, then take 12 g 1-(3-dimethylamino propyl)-3-ethyl carbodiimide hydrochloride and 6 g N-hydroxy succinimide in turn, and adjust pH to 5 with hydrochloric acid aqueous solution (concentration 1 mol / L), stir for 30 min, slowly drop the citric acid-trioxatridecanediamine free amine salt solution prepared in step (6), and adjust pH to 6 with ammonia water (concentration 2 mol / L), stir for 16 h at room temperature, after the reaction is completed, adjust pH to 3 with hydrochloric acid aqueous solution (concentration 1 mol / L), stand for 1 h, then filter and discard the insoluble substance, take the filtrate into a dialysis bag with molecular weight cut-off value of 500 Da, dialyze in deionized water for 48 h, replace the deionized water every 8 h until the conductivity is less than 100 μS / cm, adjust pH to 7 with ammonia water (concentration 2 mol / L), and freeze-dry to obtain citric acid-trioxatridecanediamine-glutamic acid diacetic acid ammonium salt;

[0053] (8) Take 169 g manganese sulfate monohydrate, add deionized water to make up to a total volume of 1000 mL, stir to dissolve, to obtain a manganese sulfate solution, take 12 g citric acid-p-phenylenediamine-glutamic acid diacetic acid ammonium salt and 13 g citric acid-trioxatridecanediamine-glutamic acid diacetic acid ammonium salt, add to the manganese sulfate solution, stir for 30 min, then adjust pH to 6 with ammonia water (concentration 2 mol / L), heat to 60°C, and drop 250 mL ammonium bicarbonate aqueous solution (concentration 1 mol / L) at a uniform speed of 45 min, maintain the temperature at 60°C, stir for 15 min, then quickly drop 250 mL ammonium bicarbonate aqueous solution (concentration 1 mol / L) at a speed of 15 min, maintain the temperature at 60°C, stir for 30 min, filter the obtained slurry and wash with deionized water until the conductivity of the filtrate is less than 50 μS / cm, take the wet filter cake and place it in a vacuum oven, dry at 80°C for 8 h, heat at 500°C for 2 h under nitrogen atmosphere, and then heat at 650°C for 4 h under air atmosphere, to obtain manganese sesquioxide for lithium ion batteries.

[0054] Example 3:

[0055] (1) Take 73.6 g of tetrasodium glutamic acid diacetate and dissolve it in 500 mL of deionized water to prepare a tetrasodium glutamic acid diacetate solution. Load 750 mL of cation exchange resin DOWEX 50WX8 into an ion exchange column, wash with 2 mol / L hydrochloric acid until the pH of the effluent is less than 2.0, and then wash with deionized water until the conductivity of the effluent is less than 10 μS / cm. Pass the tetrasodium glutamic acid diacetate solution through the ion exchange column at a flow rate of 120 mL / h, collect the effluent until the pH stabilizes at 2.2, and concentrate the effluent under reduced pressure to 500 mL to obtain a glutamic acid diacetate solution;

[0056] (2) Take 10 g of p-phenylenediamine and add it to 100 mL of anhydrous ethanol in an ice bath. Slowly add 10 g of di-tert-butyl dicarbonate and stir for 2 hours to obtain a single-tert-butyloxycarbonyl-protected p-phenylenediamine ethanol solution. Take another 10 g of citric acid and add it to 120 mL of deionized water in an ice bath. Then, add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide in sequence, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 minutes to activate, then slowly add the single-tert-butyloxycarbonyl-protected p-phenylenediamine ethanol solution, and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 14 hours to obtain a citric acid-p-phenylenediamine intermediate mixture;

[0057] (3) Take 20 mL of anhydrous ethanol hydrochloric acid solution (concentration 4 mol / L) and add it to the citric acid-p-phenylenediamine intermediate mixture prepared in step (2). Stir for 1 hour to remove the tert-butyloxycarbonyl protection, then add 200 mL of deionized water and remove the ethanol under reduced pressure. Adjust the pH to 5 with ammonia water (concentration 2 mol / L) to obtain a citric acid-p-phenylenediamine free amine salt solution;

[0058] (4) Take 250 mL of glutamic acid diacetic acid solution and place it in an ice bath. Then, add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide in sequence, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 minutes to activate, then slowly add the citric acid-p-phenylenediamine free amine salt solution prepared in step (3), and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 18 hours, then adjust the pH to 3 with an aqueous hydrochloric acid solution (concentration 1 mol / L) after the reaction is complete. Let it stand for 1 hour, then filter and discard the insoluble material. Take the filtrate and place it in a 500 Da molecular weight cutoff dialysis bag in deionized water for dialysis for 60 hours. Replace the deionized water every 8 hours until the conductivity is less than 100 μS / cm. Adjust the pH to 7 with ammonia water (concentration 2 mol / L) and freeze-dry to obtain a citric acid-p-phenylenediamine-glutamic acid diacetic acid ammonium salt;

[0059] (5) Take 12 g of 4,7,10-trioxa-1,13-tridecanediamine and add to 100 mL of anhydrous ethanol in an ice bath, then slowly add 6 g of di-tert-butyl carbonate and stir for 2 h to obtain a single-tert-butoxycarbonyl-protected trioxa-tridecanediamine ethanol solution. Take 10 g of citric acid and add to 120 mL of deionized water in an ice bath, then sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 min to activate, then slowly add the single-tert-butoxycarbonyl-protected trioxa-tridecanediamine ethanol solution, and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 14 h to obtain a citric acid-trioxa-tridecanediamine intermediate mixture;

[0060] (6) Take 20 mL of anhydrous ethanol hydrochloric acid solution (concentration 4 mol / L) and add to the citric acid-trioxa-tridecanediamine intermediate mixture prepared in step (5), and stir for 1 h to remove the tert-butoxycarbonyl protection. Add 200 mL of deionized water and remove the ethanol under reduced pressure, and adjust the pH to 5 with ammonia water (concentration 2 mol / L) to obtain a citric acid-trioxa-tridecanediamine free amine salt solution;

[0061] (7) Take 250 mL of glutamic acid diacetic acid solution and place in an ice bath, then sequentially add 12 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6 g of N-hydroxysuccinimide, and adjust the pH to 5 with an aqueous hydrochloric acid solution (concentration 1 mol / L). Stir for 30 min to activate, then slowly add the citric acid-trioxa-tridecanediamine free amine salt solution prepared in step (6), and adjust the pH to 6 with ammonia water (concentration 2 mol / L). Stir at room temperature for 18 h, then adjust the pH to 3 with an aqueous hydrochloric acid solution (concentration 1 mol / L) after the reaction is complete. Let stand for 1 h, then filter and discard the insoluble material. Take the filtrate and load into a molecular weight cutoff value 500 Da dialysis bag in deionized water and dialyze for 60 h, replacing the deionized water every 8 h until the conductivity is less than 100 μS / cm. Adjust the pH to 7 with ammonia water (concentration 2 mol / L) and freeze-dry to obtain a citric acid-trioxa-tridecanediamine-glutamic acid diacetic acid ammonium salt;

[0062] (8) Take 180 g of manganese sulfate monohydrate and add deionized water to make up to a total volume of 1000 mL and stir to dissolve, to obtain a manganese sulfate solution. Take 14 g of citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt and 16 g of citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt and add to the manganese sulfate solution and stir for 30 min. Then adjust the pH to 6 with ammonia water (concentration 2 mol / L), heat to 60°C and maintain the temperature, and add 250 mL of ammonium bicarbonate aqueous solution (concentration 1 mol / L) at a uniform speed of 40 min, maintain the temperature at 60°C, and stir and age for 20 min. Then add 250 mL of ammonium bicarbonate aqueous solution (concentration 1 mol / L) at a fast speed of 10 min, maintain the temperature at 60°C, and stir and age for 40 min. Take the obtained slurry and filter and wash with deionized water in a cycle until the conductivity of the filtrate is less than 30 μS / cm. Take the wet filter cake and place it in a vacuum oven, dry at 80°C for 8 h, heat at 500°C for 3 h in a nitrogen atmosphere, and then heat at 650°C for 5 h in an air atmosphere, to obtain manganese sesquioxide for lithium ion batteries.

[0063] Comparative Example 1:

[0064] Comparative Example 1 differs from Example 2 in that citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is not added, only 25 g of citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt is added (equivalent to the total amount of two ligands in Example 2), and the other conditions are the same as in Example 2.

[0065] Comparative Example 2:

[0066] Comparative Example 2 differs from Example 2 in that citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt is not added, only 25 g of citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is added (equivalent to the total amount of two ligands in Example 2), and the other conditions are the same as in Example 2.

[0067] Comparative Example 3:

[0068] Comparative Example 3 differs from Example 2 in that step (1) does not perform ion exchange to remove sodium, directly uses 73.6 g of glutamic acid diacetate tetrasodium solution, does not convert to acid type, and the other conditions are the same as in Example 2.

[0069] Comparative Example 4:

[0070] Comparative Example 4 differs from Example 2 in that the precipitant is changed from 1 mol / L ammonium bicarbonate aqueous solution to 1 mol / L sodium bicarbonate aqueous solution, the volume and the staging dropping time sequence and aging time remain the same, and the other conditions are the same as in Example 2.

[0071] Comparative Example 5:

[0072] Comparative Example 5 differs from Example 2 in that 1 mol / L aqueous ammonium bicarbonate solution is retained as the precipitant, but the two-stage dropwise addition is changed to a single stage: 500 mL is added at a constant rate within 60 min at 60°C, without intermediate and terminal maturation time, and the rest of the conditions are consistent with Example 2.

[0073] Comparative Example 6:

[0074] Comparative Example 6 differs from Example 2 in that the calcination procedure is changed to a single-stage air calcination at 650°C for 4 h, and the nitrogen pre-calcination stage is cancelled, and the rest of the conditions are consistent with Example 2.

[0075] Comparative Example 7:

[0076] Comparative Example 7 differs from Example 2 in that the washing endpoint is relaxed from <50 μS / cm to 200 μS / cm for the filtrate conductivity, and the rest of the conditions are consistent with Example 2.

[0077] Performance test:

[0078] Infrared spectrum test: Fourier infrared spectrometer is used for testing, and the results are shown in Figure 1 .

[0079] Tap density: GB / T 1479.1-2011 is executed, a standard tap density cylinder is used, and the tap frequency is 1x10 3 A stable value is obtained, the ambient temperature is 23±2°C, the relative humidity is 50±5%, and the results are shown in Table 1.

[0080] Sphericity and particle size distribution: Sphericity is tested according to GB / T 25915.1-2010 and GB / T 25915.2-2010, ≥1000 particles are counted in a representative field of view, and the sphericity is calculated; particle size distribution is tested according to GB / T 19077-2016, the dispersion medium is deionized water, ultrasonic dispersion is performed for 2 min, D10 / D50 / D90 is recorded, and the results are shown in Table 1.

[0081] Slurry rheology and coating defect rate: a 70wt% solid content manganese tetroxide slurry is prepared using an aqueous system (CMC:SBR (based on solid content) mass ratio 1:1, total gum amount accounting for 3wt% of solid (active substance + conductive agent + binder solid)), planetary stirring is performed for defoaming, Brookfield DV2T is used at 25°C, the speed is tested at 0.5-20 rpm in stages, and the viscosity-shear rate curve is shown in Figure 2 and Figure 3The water-based system (CMC: SBR (mass ratio of solid content 1:1, total glue amount accounting for 3wt% of solid (active substance + conductive agent + binder solid)) was used to prepare 70wt% solid content of trimanganese tetraoxide slurry, and the planetary stirring was defoamed. The experimental coater was used to coat on the aluminum foil (12μm thick) (wet film thickness 100μm), and the drying (80℃, 10min) was performed. The pinhole, bubble and flow mark defect rates (defect number / m 2 ) were recorded, and the results are shown in Table 1.

[0082] The compaction performance and the sheet density uniformity: the powder was directly pressed into a standard disc (diameter 12mm), and the sheet density was measured after 200MPa static pressure for 30s. Ten discs were prepared for each sample, and the sheet density dispersion coefficient (RSD) was recorded. The results are shown in Table 1.

[0083] Table 1 Performance test results

[0084]

[0085] Data analysis:

[0086] From the data of Examples 1-3 in Table 1, it can be seen that the trimanganese tetraoxide prepared by the present application has high and stable stacking and morphology characteristics. The coating defect number is about 7-8 / m 2 , the sheet density is about 3.70-3.82g / cm 3 , and the dispersion coefficient is about 1.5-2.3%. The possible mechanism is that the multi-dentate coordination network formed by citric acid-p-phenylenediamine, citric acid-trioxa-tridecanediamine and glutamic acid diacetate inhibits instantaneous nucleation and induces crystal face orientation at pH about 6; the segmented addition of ammonium bicarbonate provides the kinetic window of slow nucleation-dense growth-agglomeration reconstruction; strict washing reduces the soluble salt source, and the two-stage calcination gradually removes organic and ammonium salt, thereby reducing the porosity, and thus showing high tap density, good rheology and low coating defects.

[0087] From the data of Example 2 and Comparative Example 1 in Table 1, it can be seen that Example 2 is more advantageous in tap density, sphericity, coating defect rate, sheet density and dispersion coefficient, and the particle size is concentrated and the two-sided spread is controlled. It shows that the coexistence of citric acid-p-phenylenediamine-glutamic acid diacetate and citric acid-trioxa-tridecanediamine-glutamic acid diacetate in Example 2 bridges through multi-dentate coordination and flexible segments, which jointly restricts the growth orientation of crystal nucleus surface and promotes the isotropic dense agglomeration of secondary particles; when only one coordination path of rigid aromatic diamine is reserved, the coordination environment tuning ability decreases, it is difficult to establish a stable slow nucleation-dense growth window, and it is easy to appear loose agglomeration and increase in porosity, thereby reducing the stacking efficiency and amplifying the sheet density fluctuation.

[0088] From the data of Example 2 and Comparative Example 2 in Table 1, it can be seen that the particle size distribution parameters of both are close, but the tap density and tablet density of Example 2 are more excellent than those of Comparative Example 2, and the sphericity and coating defect rate are also more excellent, and the coefficient of variation is lower. Under the premise of similar particle size, the density and uniformity can still be improved, which may be due to the introduction of rigid fragments containing p-phenylenediamine and flexible chain segments containing trioxatridecanediamine, and the coordination network constructed together with glutamic acid diacetate, which realizes synergy in crystal orientation, particle surface rearrangement and secondary agglomeration densification, further reduces internal porosity, and makes the morphology closer to equiaxed, thereby improving the bulk and compaction and reducing the coating defects without changing the particle size window.

[0089] From the data of Example 2 and Comparative Example 3 in Table 1, it can be seen that Example 2 is more excellent in tap density, sphericity, D90, coating defect rate and tablet density coefficient of variation, indicating that the large particle tail and irregular morphology are effectively suppressed. It is speculated that when sodium is not fully removed, the ionic strength and charge shielding of the solution may weaken the polydentate complexation of the organic ligand, causing more intense instantaneous nucleation and agglomeration coarsening during the precipitation stage, which is manifested as D90 expansion, sphericity decrease and internal porosity increase; after desodium, the coordination-nucleation is more controllable, which is beneficial to narrower distribution and higher bulk density.

[0090] From the data of Example 2 and Comparative Example 4 in Table 1, it can be seen that the tap density, sphericity and tablet density of Example 2 are better than those of Comparative Example 4, the coating defect rate and the coefficient of variation are lower, and the particle size distribution is also more concentrated. It shows the criticality of the selection of precipitant: ammonium bicarbonate releases ammonia and forms a mild buffer at 60°C and pH about 6, gradually supplying carbonate and ammonia, which is beneficial to controllable nucleation and growth; sodium bicarbonate may produce a local high alkaline microenvironment and introduce sodium, which not only intensifies the instantaneous precipitation and morphology fragmentation, but also brings the residual of exogenous soluble salt, leading to secondary agglomeration loosening and tail particle elongation, and then weakening the bulk and coating stability.

[0091] From the data of Example 2 and Comparative Example 5 in Table 1, it can be seen that Example 2 is more excellent in tap density, sphericity, coating defect rate, tablet density and coefficient of variation, and D90 is smaller. This trend is related to the process window of segmented dropping combined with double ripening: slow dropping first and short ripening provide time for uniform and small crystal nucleus, and then rapid replenishment and re-ripening promote densification and secondary agglomeration reconstruction, which overall compresses the particle size and improves the sphericity; single-stage uniform addition without ripening may make nucleation and growth compete with each other, leading to wide particle size distribution, insufficient structure densification and fluctuating tablet density, thereby increasing the exposure of coating defects.

[0092] From the data of Example 2 and Comparative Example 6 in Table 1, it can be seen that the particle size distribution parameters of both are similar, but the tap density, sphericity, tablet density, and coating defect rate and coefficient of dispersion of Example 2 are significantly better than those of Comparative Example 6. The difference in density and morphology that occurs under the condition of similar particle size is attributed to the roasting atmosphere and temperature trajectory: mild decomposition of organic and ammonium salts and promotion of structural rearrangement are achieved by pre-roasting at medium temperature in nitrogen, followed by phase stabilization and removal of sulfate radicals in air, which reduces sintering hole sources and improves the perfection of crystal faces; if roasting is directly performed in air, oxidative decomposition and outgassing can form pores inside the particles or edge collapse, although the particle size does not change, but the effective packing and compaction are damaged, leading to a decrease in coating stability.

[0093] From the data of Example 2 and Comparative Example 7 in Table 1, it can be seen that the tap density and sphericity of Example 2 are significantly better than those of Comparative Example 7, the tail of the particle size distribution is effectively compressed, and the coating defect rate and tablet density coefficient of dispersion are lower. This shows that the control of the washing endpoint has a decisive influence on the final microstructure: when the filtrate conductivity is strictly controlled at a low level, the residual soluble sulfate and sodium, ammonium, etc. are removed, the outgassing and side reaction sources during roasting are significantly reduced, which is conducive to the formation of dense primary crystals and stable secondary agglomerates; insufficient washing induces pore and agglomeration coarsening during heating, which is manifested as a long tail of particle size, a decrease in packing efficiency, and an increase in coating defects.

[0094] From Figure 1 it can be seen that both double-ligand ammonium salt samples exhibit a broad O-H / N-H stretching band in the 3500-3300 cm -1 interval; amide I (C=O) and amide II (N-H bending / C-N) pairs of strong absorption appear at 1660±5 cm -1 and 1546±3 cm -1 , respectively, while the COO -1 symmetric stretching peak at ~1410 cm - is relatively strong, indicating that the amide bond and carboxylate structure in the target product have been formed. Further comparison shows that the citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt exhibits a continuous and relatively strong C-O-C stretching peak group at 1145 / 1110 / 1060 cm -1 ; while the citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt has more prominent aromatic ring C=C at 1600 cm -1 and para-substituted out-of-plane bending absorption at 830 / 765 cm -1 , which confirms the successful synthesis of the two double-ligand ammonium salts.

[0095] From Figure 2It can be seen that the slurries of the three embodiments all show typical shear thinning (pseudoplastic) characteristics, with the viscosity continuously decreasing and tending to a stable platform in the medium-high shear rate region, indicating that the systems have good viscosity reduction and leveling ability under actual coating shear.

[0096] From Figure 3 It can be seen that under the same conditions, the curve of Example 2 is located in a lower viscosity region as a whole, especially in the medium-high shear rate range related to actual coating, which is significantly lower than each of the comparative examples, showing more sufficient shear thinning and better coating adaptability.

[0097] Those skilled in the art should understand that the above discussion of any of the embodiments is only exemplary and is not intended to imply that the scope of the present application is limited to these examples; under the idea of the present application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in details.

Claims

1. A trimanganese tetraoxide for use in a lithium-ion battery, characterized in that, Manganese sulfate monohydrate is precipitated, washed, dried, and sequentially pre-baked in a nitrogen atmosphere and baked in an air atmosphere to obtain manganese carbonate by using a two-stage equal-volume dropwise addition of 1 mol / L ammonium bicarbonate aqueous solution at pH 6 and 60 DEG C in a double-ligand system containing citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt and citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt; The ammonium bicarbonate aqueous solution is subjected to ripening treatment after the two-stage equal-volume dropwise addition, and is washed until the conductivity of the filtrate is less than or equal to 50 muS / cm. The citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt is obtained by synthesizing a single-end protective body of p-phenylenediamine and di-t-butyl carbonate, grafting citric acid, obtaining a citric acid-p-phenylenediamine intermediate, deprotecting the p-phenylenediamine end, grafting glutamic acid diacetate, and purifying by dialysis. The citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is obtained by synthesizing a single-end protective body of 4,7,10-triox-1,13-tridecanediamine and di-t-butyl carbonate, grafting citric acid, obtaining a citric acid-trioxatridecanediamine intermediate, deprotecting the trioxatridecanediamine end, grafting glutamic acid diacetate, and purifying by dialysis.

2. The trimanganese tetraoxide for a lithium-ion battery according to claim 1, characterized by, The weight ratio of p-phenylenediamine, di-t-butyl carbonate, citric acid, and glutamic acid diacetate in the preparation raw material of the citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt is 10:10:10:

27.

3. The trimanganese tetraoxide for lithium-ion batteries according to claim 1, characterized in that, The weight ratio of 4,7,10-triox-1,13-tridecanediamine, di-t-butyl carbonate, citric acid, and glutamic acid diacetate in the preparation raw material of the citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is 12:6:10:

27.

4. The trimanganese tetraoxide for lithium-ion batteries according to claim 1, characterized in that, The citric acid-p-phenylenediamine-glutamic acid diacetate ammonium salt is 6.25-7.78 parts by mass, and the citric acid-trioxatridecanediamine-glutamic acid diacetate ammonium salt is 6.88-8.89 parts by mass, based on 100 parts by mass of manganese sulfate monohydrate.

5. The trimanganese tetraoxide for lithium-ion batteries according to claim 1, characterized in that, The amount-of-substance ratio of ammonium bicarbonate to manganese sulfate monohydrate is 0.47-0.53:

1.

6. The trimanganese tetraoxide for lithium-ion batteries according to claim 1, characterized in that, The pre-baking temperature in a nitrogen atmosphere is 500 DEG C, and the holding time is 1.5-3.0 h; the baking temperature in an air atmosphere is 650 DEG C, and the holding time is 3-5 h.

7. The trimanganese tetraoxide for lithium-ion batteries according to claim 1, characterized in that, The particle size distribution of the trimanganese tetraoxide for lithium ion batteries has a D10 of 5-6 μm, a D50 of 9-10 μm, a D90 of 14-15 μm; a tap density of 3.15-3.30 g / cm 3 ; and a sphericity of 0.94-0.

95.

8. The trimanganese tetraoxide for lithium-ion batteries according to claim 1, characterized in that, The glutamic acid diacetate is obtained by converting glutamic acid diacetate tetrasodium aqueous solution through a cation exchange resin column.

9. The trimanganese tetraoxide for lithium-ion batteries according to claim 8, characterized in that, The cation exchange resin is DOWEX 50WX8, and the sample flow rate of glutamic acid diacetate tetrasodium aqueous solution is 80-120 mL / h.

10. A process for the preparation of trimanganese tetraoxide for lithium-ion batteries according to any one of claims 1-9, comprising the steps of: Manganese sulfate monohydrate is dissolved in deionized water to obtain a solution, citric acid-p-phenylenediamine-glutamic acid diacetic acid ammonium salt and citric acid-trioxatridecanediamine-glutamic acid diacetic acid ammonium salt are added, after stirring for 30 min, the pH is adjusted to 6 with ammonia water, and the temperature is kept at 60 DEG C; ammonium bicarbonate aqueous solution is added in two equal volumes, the first segment is added for 40-50 min, matured for 10-20 min, the second segment is added for 10-20 min, and matured again for 25-40 min, filtered and washed with deionized water until the filtrate conductivity is less than or equal to 50 mu S / cm, dried at 80 DEG C for 8 h, then pre-baked in nitrogen atmosphere and baked in air atmosphere, to obtain manganese tetroxide for lithium ion battery.

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