CN100436326C - Method for preparing lithium vanadium oxide for lithium ion cell anode material - Google Patents

Abstract

The invention relates to a method for preparing Li and V oxides for anode material of Li ion batteries, grinding and mixing lithium hydroxide, ammonium melavanadate, fluorine doping agent and cation doping agent in the molar ratio of 0.95-1.40 to 3 to 0.010-0.25 to 0.030-0.25, making the mixture into discs at 80-300Kg/cm2, and preparing decorative pure Li and V oxide phase with LiV3O8 structural characteristic by stage sintering or one-stage sintering; the sintered sample naturally cools to room temperature and is ground into 100-200 meshes, where the fluorine doping agent is one of or a mixture of above two of lithium fluoride, sodium fluoride, and potassium fluoride, the cation doping agent is one of or a mixture of above two of oxides or hydroxides of Pr, Co, Ni, Mg, Al, Si, Sc, Ti, Cr, Fe, Cu, Zn, La, Zr, Nb, Mo and Wu. As sintering, it charges 10-500ml/min air or oxygen gas flow. And the product can be applied to high capacity nonaqueous Li batteries, nonaqueous Li ion batteries, Li ion polymer batteries and Li ion batteries with hydrous electrolyte.

Description

A kind of preparation method of the lithium vanadium oxide that is used for lithium-ion battery cathode material

technical field

The invention relates to a preparation method of lithium vanadium oxide used as positive electrode material of lithium ion battery, and the application of modified lithium vanadium oxide synthesized by the method in battery, especially in lithium ion battery.

technical background

Compared with other lithium-ion battery cathode materials, such as spinel lithium manganese oxide, lithium cobalt oxide, etc., there are no systematic research reports on lithium vanadium oxide at home and abroad. Therefore, it is necessary to use lithium with potential application value The transformation of vanadium oxides into practical and feasible cathode materials for lithium-ion batteries requires systematic research on lithium vanadium oxides. Past studies have shown that the factors that determine the electrochemical performance of battery materials include the discharge specific capacity of the battery, the discharge platform voltage, the shape of the discharge curve, cycle performance, and storage performance. In order to realize the practical application of lithium vanadium oxide in lithium-ion batteries, the above problems must be solved. However, at present, the research work carried out at home and abroad only involves improving the discharge performance and cycle performance of lithium vanadium oxide, but there is no research on the discharge platform voltage, discharge curve shape, and storage performance, which are more important in determining battery performance. Chinese patent CN1369435A attempts to improve the discharge specific capacity of lithium vanadium oxide and the apparent specific capacity of samples. In this patent, _the high-temperature molten NH ₄ VO _{3 is} rapidly cooled in deionized water, and the spherical V ₂ O ₅ powder, Li _1+x V ₃ O ₈ and doped Li _1+x V ₃ O are synthesized by forming a V 2 O 5 sol ₈ . In order to further improve the discharge capacity of lithium vanadium oxide, the doping method becomes an important choice. US Patent No. 6322928 grinds and mixes LiOH·H ₂ O, NH ₄ VO ₃ and methanol. After distilling off methanol, heat and sinter the solid precursor within 24 hours at a heating rate of 1°C/min in the range of 20-400°C. When preparing dopants, Mg, Al, Si, P, Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Ta, Mo, La, Hf, W. Liu Sihui et al. reacted V ₂ O ₅ , H ₂ O ₂ , Li ₂ CO ₃ and Ag ₂ CO ₃ at 120°C first, and then heated at 400°C to obtain silver-doped LiV ₃ O ₈ (Chinese Journal of Nonferrous Metals, 2004, 14 (5): 809-814). Cao Dumeng et _{al prepared Li 1 +x} V _{3 -y Mo y O 8 ( 0≤} y≤0.6) (Journal of Central South University, 2005: 36(5), 766-770). In recent years, Tong Qingsong's research group at Fujian Normal University has carried out a series of research work on the modification of lithium vanadium oxides: in the patent ZL03140888.5, according to the molar ratio of (1.0～1.2):(1.5～3.5):(0.001～0.5) LiOH·H ₂ O, NH ₄ VO ₃ and the dopant used in this invention are mixed and ground, and the doped sample is prepared by combining microwave and solid-state sintering.

Contents of the invention

In order to improve the discharge platform voltage, discharge curve shape, storage performance, etc., which are more important to the performance of the existing lithium vanadium oxide battery, improve the lithium vanadium oxide and the currently commercialized spinel lithium manganese oxide and lithium cobalt oxide. Competitiveness in terms of specific power (voltage × specific capacity), the purpose of the present invention is to provide a preparation of anion and cation doped modified lithium vanadium oxides with LiV ₃ O ₈ type structure characteristics as the positive electrode material of lithium ion battery The method, the pure phase material prepared by the method has a good discharge platform, and provides a good positive electrode material for the practical application of lithium vanadium oxide in batteries, especially in lithium ion batteries.

In order to achieve the above object, the technical scheme adopted in the present invention is: according to the molar ratio of lithium hydroxide, ammonium metavanadate, fluorine doping agent and cationic dopant being 0.95～1.40: 3: 0.010～0.25: 0.030～0.25 respectively Weigh, grind and mix evenly. The mixture is pressed into a disc shape under a pressure of 80-300 kg/ ^cm2 . The pressed disc can be sintered by segmental sintering method or one-stage sintering method. The sintered samples were naturally cooled to room temperature and ground to a size of 100-200 mesh. That is, the pure phase of the anion- and cation-doped modified lithium vanadium oxide with LiV ₃ O ₈ structure characteristics is prepared. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

The fluorine-doping agent described in the present invention is respectively one or a mixture of two or more substances in any proportion among lithium fluoride, sodium fluoride, and potassium fluoride, and the cationic dopant is praseodymium, cobalt, nickel, magnesium, aluminum, Silicon, scandium, titanium, chromium, iron, copper, zinc, lanthanum, zirconium, niobium, molybdenum and tungsten oxides or hydroxides in various valence states, or a mixture of two or more substances in any proportion.

In the segmented sintering method described in the present invention, the disc of the sample is first sintered in a tube furnace at a constant temperature between 80-150°C for 1-10 hours, and then the temperature is raised to 230-460°C Carry out the second stage of sintering for 8 to 48 hours. The optimum temperature for the second stage of sintering is any temperature between 310°C and 420°C.

The one-stage sintering method of the present invention is to directly sinter the sample disc at 230-420° C. for 15-72 hours. The optimum sintering time is 15-45 hours.

Both the segmented sintering method and the one-stage sintering method of the present invention are fed with an air or oxygen flow with a flow rate of 10-500 ml/min during the sintering process.

By using the preparation method of the invention, the chemical composition and particle size of the prepared synthetic product are uniform, and the pure phase of the doped sample with LiV ₃ O ₈ structure characteristics can be obtained. The discharge curve of the prepared sample is obviously prolonged, and the discharge platforms in the intervals of 2.8-3.2V and 2.6-2.7V are obviously improved. The method can realize large-scale industrial production, and the prepared battery material has broad application prospects in lithium-ion batteries and other battery fields. The discharge capacity of the stored and non-stored samples was higher than 210 mAh/g at 100 cycles.

Detailed ways

Below in conjunction with embodiment the present invention is further described. The examples are only further supplements and descriptions of the present invention, rather than limiting the present invention.

Example 1

Lithium hydroxide, ammonium metavanadate, lithium fluoride and PrO ₂ were weighed at a molar ratio of 0.95:3:0.010:0.030, and ground and mixed uniformly. The mixture was pressed into a disc shape under a pressure of 80 kg/ ^cm2 . The discs of the samples were first sintered in a tube furnace at 100°C for 2 hours, and then heated to 310°C for 48 hours. The sintering process is fed with an air or oxygen flow at a flow rate of 20 ml/min. The sintered samples were naturally cooled to room temperature and ground to a size of 100 mesh. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

Example 2

Lithium hydroxide, ammonium metavanadate, sodium fluoride and ZnO were weighed at a molar ratio of 1.4:3:0.03:0.15, and ground and mixed uniformly. The mixture was pressed into pellets at a pressure of 100 kg/ ^cm2 . The disc of the sample was first sintered in a tube furnace at 150°C for 8 hours, and then heated to 380°C for 39 hours. Air or oxygen flow is introduced into the sintering process, and the average flow rate of the air flow is 490 ml/min. The sintered samples were naturally cooled to room temperature and ground to a size of 200 mesh. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

Example 3

Lithium hydroxide, ammonium metavanadate, lithium fluoride, PrO ₂ and Al(OH) ₃ were weighed at a molar ratio of 1.2:3:0.01:0.01:0.02, and ground and mixed uniformly. The mixture was pressed into a disc shape under a pressure of 150 kg/ ^cm2 . The disc of the sample was first sintered in a tube furnace at 150°C for 10 hours, and then heated to 420°C for 8 hours. The sintering process is fed with an air or oxygen flow at a flow rate of 200 ml/min. The sintered samples were naturally cooled to room temperature and ground to a size of 200 mesh. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

Example 4

Lithium hydroxide, ammonium metavanadate, sodium fluoride and TiO ₂ were weighed at a molar ratio of 1.1:3:0.09:0.05, and ground and mixed uniformly. The mixture was pressed into a disc shape under a pressure of 300 kg/ ^cm2 . The discs of the samples were directly sintered at 410°C for 15 hours. The sintering process is fed with an air or oxygen flow at a flow rate of 200 ml/min. The sintered samples were naturally cooled to room temperature and ground to a size of 100 mesh. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

Example 5

Lithium hydroxide, ammonium metavanadate, lithium fluoride and Al ₂ O ₃ were weighed at a molar ratio of 1.3:3:0.15:0.03, and ground and mixed uniformly. The mixture was pressed into pellets at a pressure of 100 kg/ ^cm2 . The discs of the samples were directly sintered at 230°C for 45 hours. The sintering process is passed through an air or oxygen flow with a flow rate of 100 ml/min. The sintered samples were naturally cooled to room temperature and ground to a size of 200 mesh. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

Example 6

Lithium hydroxide, ammonium metavanadate, lithium fluoride, Al ₂ O ₃ and ZnO were weighed at a molar ratio of 1.0:3:0.15:0.05:0.19, and ground and mixed uniformly. The mixture was pressed into pellets at a pressure of 100 kg/ ^cm2 . The discs of the samples were directly sintered at 330°C for 45 hours. The sintering process is fed with an air or oxygen flow at a flow rate of 100 ml/min. The sintered samples were naturally cooled to room temperature and ground to a size of 200 mesh. The product can be applied to nonaqueous lithium batteries, nonaqueous lithium ion batteries, lithium ion polymer batteries and lithium ion batteries containing water in electrolyte solution. In application, according to the steps of assembling the battery, it can be made into a button battery or a cylindrical battery, etc.

Claims (4)

1. preparation method who is used for the modification lithium and vanadium oxides of anode material for lithium-ion batteries is characterized in that following these steps to be prepared:

(1) be 0.95～1.40 by lithium hydroxide, metavanadic acid amine, mingling fluorine agent and cation doping agent: 3: 0.010～0.25: 0.030～0.25 mol ratio takes by weighing respectively, and ground and mixed is even; With mixture in 80～300 kilograms per centimeter ²Pressure under be pressed into the disk shape; Adopt multi-steps sintering method or one-stage sintering method to carry out sintering behind the disk that is pressed into, naturally cool to room temperature, grind to form 100～200 order sizes, i.e. preparation has LiV ₃O ₈The modification lithium and vanadium oxides pure phase of the yin, yang ion doping of type constitutional features; The mixture of one or more material arbitrary proportions in the oxide compound of the various valence states that described cation doping agent is praseodymium, cobalt, nickel, magnesium, aluminium, silicon, scandium, titanium, chromium, iron, copper, zinc, lanthanum, zirconium, niobium, molybdenum and tungsten or the oxyhydroxide; Described multi-steps sintering method be with sample earlier in tube furnace in a certain steady temperature sintering of 80～150 ℃ of scopes 1～10 hour, be warming up to 230～460 ℃ of sintering then 8～48 hours, sintering temperature is the arbitrary temperature between 310～420 ℃ during second section sintering; Described one-stage sintering method be with the sample disk 230～420 ℃ of interval direct sinterings 15～72 hours, sintering time is 15～45 hours.

2, the preparation method who is used for the modification lithium and vanadium oxides of anode material for lithium-ion batteries according to claim 1 is characterized in that the described air or oxygen stream that all feeds flow velocity 10～500 ml/min in multi-steps sintering method or one-stage sintering method.

3, the preparation method who is used for the modification lithium and vanadium oxides of anode material for lithium-ion batteries according to claim 1 is characterized in that mingling fluorine agent is the mixture of one or more arbitrary proportions in lithium fluoride, Sodium Fluoride, the Potassium monofluoride.

4, the preparation method who is used for the modification lithium and vanadium oxides of anode material for lithium-ion batteries according to claim 1 is characterized in that the product for preparing can be applicable in non-water lithium cell, nonaqueous lithium ion battery, lithium ion polymer battery and electrolytic solution in the aqueous lithium ion battery.