CN103606669A - Preparation method of trivalent scandium or chromium-doped spinel-type lithium-rich lithium manganate cathode material - Google Patents

Abstract

The present invention relates to the preparation method of spinel lithium-rich lithium manganese oxide cathode material doped with trivalent scandium or chromium, which is characterized in that according to the molar ratio (0.97≤x≤1.08) of lithium, manganese and doping ions: (1.05≤y ≤1.20): (0.05≤z≤0.17) Weigh lithium, manganese, scandium compounds or chromium compounds respectively. The weighed compounds were mixed, added to wet grinding media to prepare precursor 1, and dried to prepare precursor 2. Finally, the doped spinel lithium-rich lithium manganate cathode material was prepared by two-stage sintering method. The raw material cost of the invention is low, the doping reduces the electrochemical polarization of lithium ion intercalation and extraction, improves the high-current discharge performance, and lays a good foundation for industrialization.

Description

Trivalent Preparation method of scandium or chromium spinel lithium-rich lithium manganate cathode material

technical field

The invention belongs to the technical field of battery electrode material preparation, and in particular relates to a preparation method of a lithium-rich spinel lithium manganate positive electrode material that can be used for lithium batteries, lithium ion batteries, polymer batteries and supercapacitors.

technical background

Lithium-ion batteries have the advantages of high battery voltage, high energy density, no memory effect, long cycle life, and low self-discharge. The performance of positive electrode materials plays a decisive role in the performance of lithium-ion batteries.

Manganese-based cathode materials have the advantages of low price, green and pollution-free, and are the research focus of lithium-ion batteries. Among the manganese-based cathode materials, spinel LiMn ₂ O ₄ , layered LiMnO ₂ and layered solid solution cathode materials have been studied more. Among them, the structure stability of layered _LiMnO2 during charge and discharge is poor, and there are not many studies at present. Spinel LiMn ₂ O ₄ can function in two voltage ranges of 4V and 3V. For the 4V region, it is related to the insertion and extraction of lithium ions at the tetrahedral 8a position of the spinel structure; for the 3V region, it is related to the insertion and extraction of lithium ions at the octahedron 16c position of the spinel structure. The intercalation and deintercalation of lithium ions in the tetrahedral positions of the spinel structure will not cause obvious changes in the sample structure. However, when the charge-discharge depth is too large, due to the John-Teller distortion effect of lithium ions, the intercalation and extraction of lithium ions in the octahedron will cause the sample structure to change from cubic to tetragonal, and the discharge capacity will rapidly decay. Therefore, suppressing the John-Teller distortion of spinel _LiMn2O4 is the key to improving its charge-discharge performance _. In addition, manganese in LiMn ₂ O ₄ will dissolve in the electrolyte, and the decomposition of the electrolyte during charge and discharge at higher voltages may also affect the cycle performance of electrode materials.

During the charge and discharge process of Li ₄ Mn ₅ O ₁₂ , the deintercalation reaction of lithium ions mainly occurs in the 3V region, and its theoretical discharge capacity can reach 163mAh/g. Compared with the theoretical capacity of 148mAh/g of spinel LiMn ₂ O ₄ , it is obviously improved, and it has the possibility of becoming an excellent cathode material in the 3V region. The material has a small unit cell expansion rate during charge and discharge, and has the advantages of excellent cycle performance. However, the thermal stability of Li ₄ Mn ₅ O ₁₂ is not good. Li _1+y Mn _2-y O ₄ (y < 0.33) is easily decomposed into LiMn ₂ O ₄ and Li ₂ MnO ₃ at high temperature [Manthiram A., et al., Ceram.Trans, 1998, 92: 291-302. ], making it difficult to prepare Li ₄ Mn ₅ O ₁₂ by general methods. A variety of synthetic methods have been studied in an attempt to obtain a more ideal preparation method. Including solid phase sintering method, sol-gel method, hydrothermal method and microwave sintering method.

The solid-phase sintering method is to mix lithium compounds and manganese compounds and sinter them under aerobic or oxygen-free conditions. Takada et al [Takada T., J. Solid State Chem., 1997, 130: 74-80.] combined lithium salts (LiNO ₃ , Li ₂ CO ₃ , Li(CH ₃ COO)) and manganese compounds (MnCO ₃ , Mn (NO ₃ ) ₂ , Mn ₂ O ₃ and MnO ₂ ) are mixed to prepare Li ₄ Mn ₅ O ₁₂ at a temperature range of 500°C to 800°C. Kang et al [Kang SH, et al., Electrochem. Solid-State Lett., 2000, 3(12): 536-639.] and Fumio et al [Fumio S., et al., J. Power Sources, 1997, 68 (2): 609-612.] First dry the mixed solution of LiOH·H ₂ O and Mn(Ac) ₂ ·4H ₂ O, and then sinter at 500°C to obtain Li[Li _y Mn _2-y ]O ₄ . The discharge capacity of the Li[Li _y Mn _2-y ]O ₄ samples prepared by them is 115-126mAh/g in the 3V region. In an oxygen atmosphere, Takada et al. [Takada T., et al., J. Power Sources, 1997, 68: 613-617.] found that the melt of CH ₃ COOLi and Mn(NO ₃ ) ₂ was sintered at 500°C to obtain The discharge capacity of the product in the first cycle is 135mAh/g. Shin et al [Shin Y., et al., Electrochim. Acta, 2003, 48(24): 3583–3592.] believed that when the sintering temperature is lower than 500°C, the increase in the amount of Mn ³⁺ will increase the discharge capacity. Kajiyama et al. [Kajiyama A., et al., J. Japan Soc. Powder & Powder Metallurgy, 2000, 47(11): 1139-1143; Nakamura T. et al., Solid State Ionics, 1999, 25: 167-168 .] Mixing LiOH·H ₂ O and γ-Mn ₂ O ₃ , they found that the electrochemical performance of Li ₄ Mn ₅ O ₁₂ prepared in oxygen atmosphere was better than that prepared in air atmosphere. Xu Meihua et al [Xu MH, et al., J. Phys. Chem, 2010, 114 (39): 16143–16147.] and Tian et al [Tian Y., et al., Chem. Commun., 2007: 2072–2074 .] Adding MnSO ₄ into the molten salt of LiNO ₃ and NaNO ₃ can produce nanometer Li ₄ Mn ₅ O ₁₂ in the temperature range of 470°C-480°C. Discharge of nanowires Li ₄ Mn ₅ O ₁₂ prepared by Tian et al [Tian Y., et al., Chem. Commun., 2007: 2072–2074.] in the first cycle and the 30th cycle (at 0.2C rate current) The capacities are 154.3mAh/g and 140mAh/g, respectively. Thackeray et al. [Thackeray M. M,, et al., J. Solid State Chem., 1996, 125: 274-277.; Michael M., et al., American Ceram. Soc. Bull, 1999, 82(12) : 3347-3354.] Mix LiOH·H ₂ O and γ-MnO ₂ and sinter at 600℃ to obtain Li ₄ Mn ₅ O ₁₂ . Yang et al [Yang X., et al., J. Solid State Chem., 2000, 10: 1903-1909.] combined γ-MnO ₂ or β-MnO ₂ or barium manganese or acid birnessite and molten LiNO ₃ mixed, Li _1.33 Mn _1.67 O ₄ can be prepared at 400°C. Liu Cong [Liu Cong. Synthesis and performance of lithium manganese oxide cathode material for lithium ion battery [D]. Guangdong: South China Normal University, 2009.] first mixed LiOH·H ₂ O and electrolytic MnO ₂ in absolute ethanol, Sintered at 450°C in an air atmosphere, and then ball milled in ethanol to obtain samples. The highest discharge capacity of their prepared samples was 161.1 mAh/g, and the discharge capacity at the 30th cycle was higher than 120 mAh/g.

Kim et al. [Kim J., et al., J. Electrochem. Soc, 1998, 145(4): 53-55.] added Li ₂ O ₂ to a mixed solution of LiOH and Mn(CH ₃ COO) ₂ to prepare Li _x Mn _y O _z ·nH ₂ O is obtained, and Li ₄ Mn ₅ O ₁₂ is obtained through filtration, washing, drying and solid phase sintering. They found that the initial discharge capacity of the sample prepared at 500 °C was 153 mAh/g, and the capacity decay rate was 2% after 40 cycles. Manthiram et al [Manthiram A., et al., J. Chem. Mater, 1998, 10(10): 2895-2909.] research shows that in LiOH solution, Li ₂ O ₂ first oxidizes [Mn(H ₂ O) ₆ ] ²⁺ , and then sintered at 400°C, the prepared Li ₄ Mn ₅ O ₁₂ has a discharge capacity of 160mAh/g in the first cycle.

In order to improve the process conditions of the solid phase sintering method, a two-stage sintering method was used in the preparation process. [Li Yibing et al., Nonferrous Metals, 2007, 59(3): 25-29.] put the mixture of LiOH, Mn(C ₂ O ₄ ) ₂ and H ₂ C ₂ O ₄ in the air atmosphere, respectively at 350 ℃ and 500℃ sintering to prepare micron Li ₄ Mn ₅ O ₁₂ . The discharge capacity of the prepared sample in the first cycle was 151mAh/g. Gao et al [Gao J., et al., Appl. Phys. Lett., 1995, 66(19): 2487-2489.; Gao J., et al., J. Electrochem. Soc., 1996, 143(6 ):1783-1788.] Spinel Li _1+x Mn _2-x O _4x (0<x≤0.2) was prepared by two-step heating method. Robertson et al [Robertson AD, et al., J. Power Sources, 2001, 97-97: 332-335.] mixed Li ₂ CO ₃ into the Mn(CH ₃ COO) ₂ 4H ₂ O solution, and dried to obtain the precursor things. Li ₄ Mn ₅ O ₁₂ was prepared by sintering at 250℃ and 300-395℃ respectively. The discharge capacities of the samples at the 1st cycle and the 50th cycle were 175mAh/g and 120mAh/g, respectively. Wang et al [Wang GX, et al., J. Power Sources, 1998, 74(2): 198-201.] synthesized Li ₄ Mn ₅ O ₁₂ at 380°C. Xia [Xia YY, et al., J. Power Sources, 1996, 63(1): 97-102.] etc. made samples by direct sintering at 260°C by injection method. Under C/3 current, the initial discharge capacity of this sample is 80mAh/g.

The above studies show that the preparation of Li ₄ Mn ₅ O ₁₂ by solid-state sintering needs to be carried out in pure O ₂ or air atmosphere. The disadvantages of this method include large differences in the composition and particle size distribution of the synthesized products, high capacity decay rate of the sample charge-discharge cycle, poor high-current discharge performance, and even less ideal high-temperature cycle performance.

In order to improve the uniformity of the sample and reduce the particle size of the sample, the sol-gel method was used to prepare Li ₄ Mn ₅ O ₁₂ [Hao YJ, et al., J. Solid State Electrochem., 2009, 13: 905–912 ; Meng Lili et al., Inorganic Salt Industry, 2009, 46(5): 37-39; Chu HY, et al., J. Appl. Electrochem, 2009, 39: 2007-2013.]. [Zhang Huiqing et al., Battery, 2004, 34(3): 176-177.] made a mixture of LiOH·2H ₂ O, Mn(CH ₃ COO) ₂ ·4H ₂ O and citric acid at 300 ℃ and 500 ℃ sintering to produce micro spinel Li ₄ Mn ₅ O ₁₂ .

In order to improve the homogeneity of the samples, reduce the particle size of the sample particles, and lower the sintering temperature, the hydrothermal method was also used in the preparation process. Zhang[Zhang YC, et al., Mater. Res. Bull., 2002, 37(8): 1411-1417.; Zhang Yongcai. Hydrothermal and Solvothermal Synthesis of Metastable Functional Materials[D]. Beijing: Beijing Industry University, 2003.; Zhang YC, et al., J. Solid State Ionics, 2003, 158(1): 113-117.] etc. first react the mixed solution of H ₂ O ₂ , LiOH and Mn(NO ₃ ) ₂ The fibrous precursor Li _{x Mny} O _z ·nH ₂ O was prepared, and then reacted with LiOH solution in low-temperature hydrothermal reaction to prepare nano Li ₄ Mn ₅ O ₁₂ . Zhang Shichao et al [Zhang Shichao et al. A method for synthesizing Li ₄ Mn ₅ O ₁₂ submicron rods [P]. CN 201010033605.2, application date 2010.01.04.] MnSO ₄ ·H ₂ O, KMnO ₄ and hexadecyl tri The mixture of methyl ammonium bromide is hydrothermally reacted in the temperature range of 140°C-180°C to produce submicron MnOOH, then mixed with LiOH·H ₂ O, and finally Li ₄ Mn ₅ O ₁₂ is produced at 500°C-900°C. Sun Shuying et al [Sun Shuying et al., Inorganic Materials Herald, 2010, 25(6): 626-630.] prepared nanometer β-MnO from MnSO ₄ ·H ₂ O and (NH ₄ ) ₂ S ₂ O ₈ through hydrothermal reaction ₂ , Li ₄ Mn ₅ O ₁₂ was prepared by low-temperature solid-state reaction after mixing LiNO ₃ .

Because microwave sintering has the advantages of fast sintering speed and simple sintering process, microwave sintering or solid phase sintering-microwave sintering combined method is used to synthesize LiMn ₂ O ₄ . Ahniyaz et al [Ahniyaz A., et al., J. Eng. Mater. Technol., 2004, 264-268: 133-136.] synthesized a mixture of γ-MnOOH, LiOH and H ₂ O ₂ by microwave sintering LiMn ₂ O ₄ . Tong Qingsong’s research group used LiOH and Mn(CH ₃ COO) ₂ as raw materials [Lin Suying et al., Fujian Chemical Industry, 2004, 2: 1-4.; Tong Qingsong et al., Electrochemistry, 2005, 11(4): 435-439.] or Using LiOH and MnC ₂ O ₄ as raw materials [Tong Qingsong et al., Journal of Fujian Normal University, 2006, 22(1): 60-63.], using ethylenediaminetetraacetic acid disodium salt (EDTA) and citric acid as complexing agents , a spinel Li _3.22 Na _0.569 Mn _5.78 O ₁₂ sample or Li ₄ Mn ₅ O ₁₂ cathode material was prepared at 380 °C by microwave-solid-state two-stage sintering method. The research shows that in the voltage range of 4.5-2.5V, the discharge capacity of the prepared Li _3.22 Na _0.569 Mn _5.78 O ₁₂ sample in the first cycle is 132mAh/g, and the capacity decay rate in 100 cycles is 6.8%. After 4 months of storage, the initial discharge capacity of the sample was 122mAh/g, and the capacity decay rate after 100 cycles was 17.4%.

[Guo Junming et al., Functional Materials, 2006, 37: 485-488.] Lithium nitrate and manganese nitrate (or lithium acetate and manganese acetate) were used as raw materials, urea was used as fuel, and Li ₄ Mn ₅ O ₁₂ . They found that the phase purity of Li ₄ Mn ₅ O ₁₂ synthesized in the acetate system was higher than that synthesized in the nitrate system. Kim et al. [Kim HU, et al., Phys. Scr, 2010, 139: 1-6.] found that the sample sintered at 400°C by the liquid phase synthesis route contained a trace amount of Mn ₂ O ₃ . Under 1C rate current, the discharge capacity of the sample in the first cycle is 44.2mAh/g. Zhao et al [Zhao Y., et al., Electrochem. Solid-State Lett., 2010, 14: 1509–1513.] synthesized nano-spinel Li ₄ Mn ₅ O ₁₂ by water-in-oil microemulsion method.

Due to the low structural stability of the spinel Li ₄ Mn ₅ O ₁₂ prepared by the above method during charge and discharge, there are problems such as low temperature discharge, high temperature cycle, and poor discharge performance under high current. It has been modified by surface coating, adding polymers, and doping with anions or cations.

In order to improve the cycle performance of Li ₄ Mn ₅ O ₁₂ , Liu Cong [Liu Cong, Synthesis and performance of lithium manganese oxide cathode material for lithium ion batteries, dissertation of South China Normal University, 2009.] mixed polyvinylpyrrolidone solution with 450 °C prepared The precursors are mixed, and Li ₄ Mn ₅ O ₁₂ is prepared through hydrothermal low-temperature treatment, vacuum treatment, drying and oxygen atmosphere treatment at 100°C. The research shows that at a rate current of 0.5C, the discharge capacities of the samples in the first cycle and the 50th cycle are 137mAh/g and 126mAh/g, respectively.

In order to further improve the performance _of spinel _Li4Mn5O12 , cation and anion doping methods have been adopted to improve the performance of _the samples. [Zhang DB, et al., J. Power Sources, 1998, 76: 81-90.] used CrO _2.65 , Li(OH)·H ₂ O and MnO ₂ as raw materials, respectively at 300°C in an oxygen atmosphere And sintering at 450℃, prepared Li ₄ Cr _y Mn _5-y O ₁₂ (y=0, 0.3, 0.9, 1.5, 2.1). The research shows that the discharge capacity of the Li ₄ Cr _1.5 Mn _3.5 O ₁₂ sample is 170mAh/g and 152Ah/g in the 1st cycle and 100th cycle under the current of 0.25mA/cm ² . Robertson et al [Robertson AD, et al., J. Power Sources, 2001, 97-97: 332-335.] in Mn(CH ₃ COO) ₂ 4H ₂ O and Co(CH ₃ COO) ₂ 4H ₂ O Li ₂ CO ₃ was first added to the mixed solution to prepare the precursor, which was dried and sintered at 250°C and 430-440°C respectively to obtain Li _4-x Mn _5-2x Co _3x O ₁₂ samples. The discharge capacities of this sample at the 1st cycle and the 50th cycle were 175 mAh/g and 120 mAh/g, respectively. Compared with Li ₄ Mn ₅ O ₁₂ , the structure of Li _4-x Mn _5-2x Co _3x O ₁₂ is more stable during the charge-discharge cycle. Among them, the discharge capacity of Li _3.75 Mn _4.5 Co _0.075 O ₁₂ in the first cycle is 150mAh/g, and the capacity decay rate in 50 cycles is close to 0%. Choi et al [Choi W., et al., Solid State Ionics, 2007, 178: 1541-1545.] mixed LiOH, LiF and Mn(OH) ₂ and sintered them in two stages at 500°C and 600°C in an air atmosphere Preparation of Li ₄ Mn ₅ O _{12 − η} F _η (0≤η≤0.2). Among them, at a rate current of 0.2C, the discharge capacity of Li ₄ Mn ₅ O _11.85 F _0.1 prepared at 500°C in the first cycle was 158mAh/g. After charging and discharging for 50 cycles at 25 °C and 60 °C, the capacity decay rate of the sample was 2.9% and 3.9%, respectively, indicating that the initial discharge capacity and cycle performance of the fluorine-doped sample were improved at high and low temperatures.

Although the above methods can improve the electrochemical performance of the samples to varying degrees, however, due to the insufficient stability of the spinel Li ₄ Mn ₅ O ₁₂ structure, the discharge performance is poor at low temperature and high current discharge conditions, and the cycle performance at high temperature is poor. will be noticeably attenuated. For this reason, the present invention promotes the actual oxidation state of manganese in Li ₄ Mn ₅ O ₁₂ by doping scandium or chromium, delays the process that the oxidation state of manganese is lower than +3.5 in the discharge process, reduces Jahn-Teller distortion to effect on structural stability. Given the following parameters, ∆H _{f 298 Sc-O} = 674 kJ mol ^{− 1} , ∆H _{f 298 Cr-O} = 427 kJ mol ^{− 1} , ∆H _{f 298 OCr-O} = 531 kJ mol ^{− 1} , ∆H _{f 298 Mn-O} = 402 kJ mol ^{− 1} , r _Sc-O = 74.5pm (Sc oxidation state is +3, and its coordination number is 6), r _Cr-O = 61.5 pm (Cr oxidation state is +3, And its coordination number is 6), r _{Mn -O} = 39pm (Mn oxidation state is +4, and its coordination number is 4), r _{Mn -O} = 53pm (Mn oxidation state is +4, and its coordination number is 6) [John A. Dean, Handbook of Chemistry (15 ^th edition)]. It can be seen from the above parameters that the Sc-O bond and Cr-O bond are much stronger than the Mn-O bond, and the ionic radius of scandium ions and chromium ions is larger than that of manganese ions. Therefore, a small amount of scandium ions or chromium ions are used instead of Part of the manganese ions will not have a large impact on the doping-like structure. Since scandium ions or chromium ions are slightly larger than the original manganese ions in the spinel structure, the unit cell structure of the doped sample is expanded, and lithium ions are more easily intercalated and extracted in the doped sample, reducing the lithium ion density. Electrochemical polarization upon intercalation and deintercalation. In addition, because the doped scandium ions or chromium ions show an oxidation state of +3 in the doped sample, which increases the relative oxidation state of the manganese ions and delays the process of Jahn-Teller distortion of the manganese ions, making the prepared doped samples The cycle performance has been significantly improved.

Contents of the invention

In order to avoid the shortcomings of the prior art, the present invention adopts the method of doping scandium ions or chromium ions to improve the stability of the spinel Li ₄ Mn ₅ O ₁₂ structure, and reduce the electrochemical polarization when lithium ions are intercalated and extracted. The technical scheme adopted for realizing the purpose of the present invention is:

Step 1: According to the molar ratio of lithium ions, manganese ions, and dopant ions as x:y:z, weigh the lithium compound, the manganese compound, and the doped compound respectively. The value ranges of x, y and z satisfy the following relational expressions at the same time: 1.20≤y+z≤1.25, 0.97≤x≤1.08, 1.05≤y≤1.20, 0.05≤z≤0.17.

Step 2: Mix the lithium compound, manganese compound and doping compound weighed in step 1, add wet grinding media with a volume of 1 to 15 times the total volume of the mixed solids, and wet grind and mix with wet grinding equipment 3 hours to 15 hours, the precursor 1 was prepared. Precursor 1 is dried to prepare dry precursor 2 by normal pressure drying, vacuum drying or spray drying. Precursor 2 is placed in air, oxygen-enriched air or pure oxygen atmosphere, and the spinel lithium-rich lithium manganese oxide positive electrode material is prepared by a two-stage sintering method.

The two-stage sintering method is carried out as follows: the dry precursor 2 is placed in air, oxygen-enriched air or pure oxygen atmosphere, and sintered at any temperature in the temperature range of 150°C to 300°C for 3 hours to 15 hours, and then according to Heating rate from 1°C/min to 30°C/min Heating from the previous sintering temperature to any temperature in the temperature range of 400°C to 600°C, keeping the temperature for sintering for 3 hours to 24 hours to prepare spinel lithium-rich lithium manganese oxide positive electrode Material.

The doping ions are scandium ions or chromium ions.

The doping compound is scandium compound or chromium compound.

The scandium compound is Sc ₂ O ₃ , scandium nitrate, ScCl ₃ , Sc(OH) ₃ , Sc ₂ (SO ₄ ) ₃ or Sc ₂ (C ₂ O ₄ ) ₃ .

The chromium compound is Cr ₂ O ₃ , chromium hydroxide, chromium potassium sulfate, chromium sulfate or chromium trichloride.

The lithium compound is lithium carbonate, lithium hydroxide, lithium acetate, lithium nitrate, lithium chloride or lithium citrate.

The manganese compound is manganese carbonate, basic manganese carbonate, manganese hydroxide, manganese acetate, manganese nitrate, manganese chloride or manganese citrate.

The atmospheric pressure drying is to place the precursor 1 at any temperature in the temperature range of 140° C. to 280° C., and dry it under 1 atmospheric pressure to prepare the precursor 2 . The vacuum drying is to place the precursor at any temperature in the temperature range of 80°C to 280°C and dry it at any pressure in the pressure range of 10Pa to 10132Pa to prepare the precursor 2. The spray drying method is to place the precursor 1 at any temperature in the temperature range of 130° C. to 280° C. and dry it with a spray dryer to prepare the precursor 2 .

The wet grinding medium is deionized water, distilled water, ethanol, acetone, methanol or formaldehyde.

The oxygen-enriched air is oxygen-enriched air with an oxygen volume content greater than 21% and less than 100%.

The wet milling equipment includes ordinary ball mills, super energy ball mills or wet mills.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization of lithium ion intercalation and extraction is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Description of drawings

Fig. 1 is a discharge curve diagram of the first cycle of the sample prepared in Example 1 of the present invention.

Fig. 2 is the XRD diffraction pattern of the sample prepared in Example 1 of the present invention and the corresponding JCPDS card.

Detailed ways

The present invention will be further described below in conjunction with examples. The examples are only further supplements and descriptions of the present invention, rather than limiting the invention.

Example 1

Lithium hydroxide, manganese nitrate and Sc(OH) ₃ were weighed respectively according to the molar ratio of lithium ion, manganese ion and scandium ion being 0.99 : 1.20 : 0.05.

Mix the weighed lithium hydroxide, manganese nitrate and Sc(OH) ₃ , add ethanol 10 times the volume of the total solid volume, and wet-mill and mix for 12 hours with a super-energy ball mill to prepare precursor 1. Precursor 1 was vacuum-dried at 180° C. and 100 Pa to prepare Precursor 2 . Precursor 2 was placed in an oxygen-enriched air atmosphere with an oxygen volume content of 63%, sintered at 197°C for 12 hours, then heated from 197°C to 530°C at a heating rate of 5°C/min, and kept at the temperature for sintering for 20 hours to prepare the tip. Spar lithium-rich lithium manganese oxide cathode material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization of lithium ion intercalation and extraction is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Example 2

Lithium carbonate, basic manganese carbonate and Cr ₂ O ₃ were weighed according to the molar ratio of lithium ion, manganese ion and chromium ion being 1.02 : 1.08 : 0.17, respectively.

Mix the weighed lithium carbonate, basic manganese carbonate and Cr ₂ O ₃ , add deionized water 15 times the volume of the total solid volume, and use a super energy ball mill for wet grinding and mixing for 12 hours to prepare precursor 1. Precursor 1 was placed at 130°C and dried with a spray dryer to prepare Precursor 2. Precursor 2 was placed in an oxygen-enriched air atmosphere with an oxygen volume content of 99%, sintered at 290°C for 3 hours, then heated from 290°C to 495°C at a heating rate of 1°C/min, and kept at the temperature for sintering for 19 hours to prepare the tip. Spar lithium-rich lithium manganese oxide cathode material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization of lithium ion intercalation and extraction is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Example 3

According to the molar ratio of lithium ion, manganese ion and scandium ion is 0.97: 1.05: 0.15 Weigh lithium acetate, manganese chloride and scandium nitrate respectively.

Mix the weighed lithium acetate, manganese chloride and scandium nitrate, add acetone that is 1 times the volume of the total solid volume, and wet grind and mix for 3 hours with an ordinary ball mill to prepare the precursor 1. Precursor 1 was vacuum-dried at 80° C. and 10 Pa pressure to prepare Precursor 2 . Precursor 2 was placed in an oxygen-enriched air atmosphere with an oxygen volume content of 22%, sintered at 150°C for 3 hours, then heated from 150°C to 400°C at a heating rate of 1°C/min, and kept at the temperature for sintering for 3 hours to prepare a tip Spar lithium-rich lithium manganese oxide cathode material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization of lithium ion intercalation and extraction is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Example 4

Lithium chloride, manganese carbonate and Sc ₂ (C ₂ O ₄ ) ₃ were weighed respectively according to the molar ratio of lithium ion, manganese ion and scandium ion being 1.08 : 1.20 : 0.05.

Mix the weighed lithium chloride, manganese carbonate and Sc ₂ (C ₂ O ₄ ) ₃ , add distilled water 12 times the volume of the total solid volume, and wet grind and mix for 15 hours with a wet grinder to prepare precursor 1. Precursor 1 was vacuum-dried at 280° C. and a pressure of 10132 Pa to prepare Precursor 2 . Precursor 2 was placed in an oxygen-enriched air atmosphere with an oxygen volume content of 99%, sintered at 300°C for 15 hours, then heated from 300°C to 600°C at a heating rate of 30°C/min, and kept at the temperature for sintering for 24 hours to prepare the tip. Spar lithium-rich lithium manganese oxide cathode material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization of lithium ion intercalation and extraction is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Example 5

According to the molar ratio of lithium ion, manganese ion and chromium ion is 1.08 : 1.08 : 0.12 Weigh lithium carbonate, manganese hydroxide and chromium sulfate respectively.

Mix the weighed lithium carbonate, manganese hydroxide and chromium sulfate, add methanol with a volume 1 times the total volume of the solids, and use a super energy ball mill for wet grinding and mixing for 15 hours to prepare precursor 1. Precursor 1 was placed at 280°C and dried with a spray dryer to prepare Precursor 2. Precursor 2 was placed in an air atmosphere, sintered at 300°C for 15 hours, then heated from 300°C to 400°C at a heating rate of 2°C/min, and kept at the temperature for sintering for 24 hours to prepare a spinel lithium-rich lithium manganate cathode Material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization of lithium ion intercalation and extraction is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Example 6

According to the molar ratio of lithium ion, manganese ion and chromium ion is 1: 1.11: 0.11 Weigh lithium hydroxide, manganese nitrate, and chromium trichloride respectively.

Mix the weighed lithium hydroxide, manganese nitrate, and chromium trichloride, add 5 times the volume of methanol of the total volume of the solid, and wet grind and mix for 12 hours with a wet grinder to prepare the precursor 1. Precursor 1 was dried at 280°C and 1 atmosphere to prepare Precursor 2. Precursor 2 was placed in a pure oxygen atmosphere, sintered at 275°C for 10 hours, then heated from 275°C to 539°C at a heating rate of 1°C/min, and kept at the temperature for sintering for 3 hours to prepare spinel lithium-rich lithium manganate Cathode material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization when lithium ions are intercalated and extracted is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Example 7

According to the molar ratio of lithium ion, manganese ion and chromium ion is 1: 1.11: 0.11 Weigh lithium hydroxide, manganese nitrate, and chromium trichloride respectively.

Mix the weighed lithium hydroxide, manganese nitrate, and chromium trichloride, add methanol 10 times the volume of the total solid volume, and wet grind and mix for 15 hours with a wet mill to prepare precursor 1. Precursor 1 was dried at 140° C. and 1 atmosphere to prepare Precursor 2 . Precursor 2 was placed in an air atmosphere, sintered at 285°C for 10 hours, then heated from 285°C to 539°C at a heating rate of 1°C/min, and kept at the temperature for sintering for 10 hours to prepare a spinel lithium-rich lithium manganate cathode Material.

Compared with other inventive methods, the raw material cost of the present invention is lower, the electrochemical polarization when lithium ions are intercalated and extracted is reduced, the high-current discharge performance is improved, and a good foundation is laid for industrialization.

Claims (8)

1. In 1. the preparation method of the spinel lithium-rich lithium manganate cathode material doped with trivalent scandium or chromium, it is characterized in that the preparation process consists of the following steps: Step 1: Weigh lithium compounds, manganese compounds, and doped compounds according to the molar ratio x: y: z of lithium ions, manganese ions, and dopant ions; the value ranges of x, y, and z are simultaneously Satisfy the following relational formula: 1.20≤y+z≤1.25, 0.97≤x≤1.08, 1.05≤y≤1.20, 0.05≤z≤0.17; the doping ions are scandium ions or chromium ions; the doping ions The compound is a compound of scandium or a compound of chromium; Step 2: Mix the lithium compound, manganese compound and doping compound weighed in step 1, add wet grinding media with a volume of 1 to 15 times the total volume of the mixed solids, and wet grind and mix with wet grinding equipment 3 hours to 15 hours to prepare precursor 1; dry precursor 1 by normal pressure drying, vacuum drying or spray drying to prepare dry precursor 2; place precursor 2 in air, oxygen-enriched air or pure oxygen atmosphere , using a two-stage sintering method to prepare spinel lithium-rich lithium manganate cathode material; The two-stage sintering process is carried out as follows: Place the dry precursor 2 in air, oxygen-enriched air or pure oxygen atmosphere, and sinter at any temperature in the temperature range of 150°C to 300°C for 3 hours to 15 hours, and then follow the steps of 1°C/min to 30°C/min The heating rate is heated from the previous sintering temperature to any temperature in the temperature range of 400° C. to 600° C., and the temperature is kept for sintering for 3 hours to 24 hours to prepare the spinel lithium-rich lithium manganese oxide positive electrode material. 2. the preparation method of the spinel lithium-rich lithium manganate cathode material doped with trivalent scandium or chromium according to claim 1, is characterized in that the compound of described lithium is lithium carbonate, lithium hydroxide, lithium acetate, Lithium nitrate, lithium chloride or lithium citrate. 3. The preparation method of spinel lithium-rich lithium manganese oxide cathode material doped with trivalent scandium or chromium according to claim 1, characterized in that the compound of scandium is Sc ₂ O ₃ , scandium nitrate, ScCl ₃ , Sc(OH) ₃ , Sc ₂ (SO ₄ ) ₃ or Sc ₂ (C ₂ O ₄ ) ₃ ; the chromium compound is Cr ₂ O ₃ , chromium hydroxide, potassium chromium sulfate, chromium sulfate or trichloro Chromium. 4. the preparation method of the spinel lithium-rich lithium manganate cathode material doped with trivalent scandium or chromium according to claim 1, it is characterized in that the compound of described manganese is manganese carbonate, basic manganese carbonate, hydroxide Manganese, manganese acetate, manganese nitrate, manganese chloride or manganese citrate. 5. The preparation method of trivalent scandium or chromium-doped spinel lithium-rich lithium manganese oxide positive electrode material according to claim 1, characterized in that the normal pressure drying is to place the precursor 1 at 140° C. to 280° C. Dry at any temperature in the temperature range of °C under 1 atmospheric pressure to prepare precursor 2; the vacuum drying is to place the precursor 1 at any temperature in the temperature range of 80 °C to 280 °C, and in the pressure range of 10 Pa to 10132 Pa Dry under any pressure to prepare precursor 2; the spray drying is to place the precursor 1 at any temperature in the temperature range of 130°C to 280°C, and dry it with a spray dryer to prepare the precursor 2. 6. the preparation method of the spinel lithium-rich lithium manganate cathode material doped with trivalent scandium or chromium according to claim 1, is characterized in that described wet grinding medium is deionized water, distilled water, ethanol, acetone, methanol or formaldehyde. 7. The preparation method of spinel lithium-rich lithium manganate positive electrode material doped with trivalent scandium or chromium according to claim 1, characterized in that the oxygen-enriched air has an oxygen volume content greater than 21% and less than 100% the air in between. 8. The preparation method of the spinel lithium-rich lithium manganese oxide positive electrode material doped with trivalent scandium or chromium according to claim 1, characterized in that the wet grinding equipment is an ordinary ball mill, a super energy ball mill or a wet mill .

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