CN107244693B

CN107244693B - Li0.5TiO2Method for preparing powder material

Info

Publication number: CN107244693B
Application number: CN201710369385.2A
Authority: CN
Inventors: 陈玉喜; 匡艳
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2017-05-23
Filing date: 2017-05-23
Publication date: 2022-01-14
Anticipated expiration: 2037-05-23
Also published as: CN107244693A

Abstract

The invention relates to a functional material Li_0.5TiO₂The preparation method of the powder comprises the step of preparing the powder by TiO under the protection of argon₂And Li₂CO₃Sintering at 650 ℃ for 8 hours as a reactant to obtain Li₂TiO₃And (3) powder. Mg powder is used as a reducing agent, and Li is reduced under the high-temperature condition in the protective atmosphere of argon₂TiO₃Powder, MgO and Li in product₂O is removed by washing with dilute hydrochloric acid to give Li_0.5TiO₂And (3) powder materials. The preparation method has the advantages of low preparation temperature, low energy consumption, simple preparation process and easy industrial production.

Description

Li0.5TiO2Method for preparing powder material

Technical Field

The invention relates to a preparation method of an electrode material of a lithium ion battery, in particular to a negative active material Li_0.5TiO₂A method for preparing powder material. The invention belongs to the field of functional materials.

Background

In recent years, with the rapid development of portable consumer electronics and new energy electric vehicles, people have made higher demands on the capacity, cycle life, safety and the like of lithium ion batteries. At present, various graphite carbon materials are adopted as negative active materials of commercial lithium ion batteries, but the graphite carbon materials are close to metal lithium in lithium intercalation potential, so lithium dendrite is likely to be separated out and penetrate through battery separators, and accidents such as combustion or explosion are likely to be caused. In recent years, Li-Ti-O series compounds have attracted much attention as electrode materials for lithium ion batteries. Wherein Li₄Ti₅O₁₂Has zero strain characteristic and long cycle life, and has higher lithium intercalation potential than that of metallic lithium, thereby having excellent safety. But Li₄Ti₅O₁₂Has a theoretical specific capacity of only 175mAh/g and a very low conductivity of only 10 at 20 DEG C^-9s/cm, which limits its application. Spinel-structured LiTi₂O₄Has higher conductivity as a negative electrode material, therefore, LiTi₂O₄Is a promising anode material. A number of preparations of LiTi have been proposed₂O₄Such as Kai Jiang et al, electrolyze TiO in a molten LiCl salt solution at 700 deg.C₂(anatase) preparation of LiTi₂O₄(Journal of Power Sources 175(2008) 575-. Furthermore, Li_0.5TiO₂Can also be used as the cathode material of the lithium ion battery,for example, A, Kuhn, et al, use a two-step high temperature reaction to prepare Li_0.5TiO₂(Journal of Power Sources 92(2001)221-227)，

Li₂CO₃+TiO₂(r)→Li₂TiO₃+CO₂

Li₂TiO₃+1/2Ti+5/2TiO₂→4Li_0.5TiO₂。

The invention utilizes Li₂TiO₃Li is produced by a simple magnesiothermic reduction method as a raw material_0.5TiO₂And (3) powder materials.

Disclosure of Invention

The invention aims to provide Li_0.5TiO₂A method for preparing powder material. The material has the advantages of excellent electrochemical performance, simple preparation process, low energy consumption and low cost.

The invention is realized by the following scheme:

1. adding TiO into the mixture₂Powder with Li₂CO₃Fully grinding and mixing according to a certain molar ratio, and then preserving heat for 8 hours at 650 ℃ in a heating furnace under the atmosphere of high-purity argon to obtain Li₂TiO₃。

2. Mixing Li₂TiO₃Fully grinding and mixing the powder and Mg powder according to a certain molar ratio, putting the mixed powder into a heating furnace for heating, and introducing high-purity argon as protective gas. The reaction temperature is kept at 600-640 ℃ for 3-6 h. Washing the reaction product in an acid solution, filtering and drying to obtain Li_0.5TiO₂And (3) powder materials.

Compared with the prior art, the invention has the following advantages:

1. li prepared by the invention_0.5TiO₂The powder material has high specific capacity and excellent charge-discharge cycling stability.

2. The preparation method has the advantages of low preparation temperature, high efficiency, energy conservation, simple and convenient process flow, low cost and easy industrial production.

Drawings

FIG. 1 Li₂TiO₃X of (a)A diffraction spectrum of radiation and (b) a scanning electron micrograph.

FIG. 2 Li₂TiO₃Li obtained by keeping the temperature of the Li and Mg powder at 600 ℃ for 6h_0.5TiO₂The (a) X-ray diffraction spectrum and (b) scanning electron micrograph of (a); (c) li_0.5TiO₂Constant current charge-discharge cycle performance.

FIG. 3 Li₂TiO₃Li obtained by keeping the temperature of the Li and Mg powder at 620 ℃ for 4h_0.5TiO₂The (a) X-ray diffraction spectrum and (b) scanning electron micrograph of (a); (c) li_0.5TiO₂Constant current charge-discharge cycle performance.

FIG. 4 Li₂TiO₃Li obtained by keeping the temperature of the Li and Mg powder at 640 ℃ for 3h_0.5TiO₂The (a) X-ray diffraction spectrum and (b) scanning electron micrograph of (a); (c) li_0.5TiO₂Constant current charge-discharge cycle performance.

Detailed Description

Example 1

Adding TiO into the mixture₂Powder with Li₂CO₃Respectively weighing corresponding masses according to a molar ratio of 1:1.05, and fully grinding and uniformly mixing the two materials. The mixed sample is contained in a corundum crucible and is kept at 650 ℃ for 8 hours in a tubular furnace filled with high-purity argon to obtain Li₂TiO₃And (3) powder materials.

Mixing Li₂TiO₃Weighing two samples with corresponding mass according to the molar ratio of 2:1.05 with Mg, fully grinding and mixing, placing the fully mixed samples in a corundum crucible, and then placing the corundum crucible into a tubular furnace filled with high-purity argon for heat preservation at 600 ℃ for 6 hours to perform magnesiothermic reduction reaction. Putting the product obtained after the reaction into a dilute hydrochloric acid solution, stirring for 1h, then repeatedly washing the remainder with alcohol and deionized water, centrifuging and drying to obtain Li_0.5TiO₂And (3) powder materials.

FIG. 1(a) is Li₂TiO₃X-ray diffraction spectrum of (1), with Li₂TiO₃The standard spectrum (PDF #33-0831) of (A) is completely consistent, indicating that under the condition, pure-phase Li can be obtained₂TiO₃. FIG. 2(b) is Li₂TiO₃Scanning electrodeMirror photograph, from which Li can be seen₂TiO₃The particle size of (A) is about 100 to 300 nm.

FIG. 2(a) is an X-ray diffraction spectrum of a magnesiothermic reduction product, together with a hexagonal structure of LiTiO₂The standard map (PDF #40-1053) of (A) was completely matched. Atomic emission spectrometry of inductively coupled plasma showed that the atomic ratio of Li to Ti in the product was 0.5:1, and thus the product was Li_0.5TiO₂. FIG. 2(b) is Li_0.5TiO₂The scanning electron microscope photo of the powder material has a particle size of 100-200 nm. Mixing Li_0.5TiO₂The powder material is prepared into a lithium ion experimental battery, and FIG. 2(c) shows Li_0.5TiO₂At a current density of 0.11mA cm^-2Cycling performance under current density conditions. The first charging/discharging specific capacity is 137.9/309.9mAh/g, and after 100 cycles, the first charging/discharging specific capacity is 44.9/45.4mAh/g respectively.

Example 2

Prepared Li₂TiO₃Weighing two samples with corresponding mass according to the molar ratio of 2:1.2 with Mg, fully grinding and mixing, placing the fully mixed samples in a corundum crucible, and then placing the corundum crucible into a tubular furnace filled with high-purity argon for heat preservation at 620 ℃ for 4 hours to carry out magnesiothermic reduction reaction. Putting the product obtained after the reaction into a dilute hydrochloric acid solution, stirring for 1h, then repeatedly washing the remainder with alcohol and deionized water, centrifuging and drying to obtain Li_0.5TiO₂And (3) powder materials.

FIG. 3(a) is an X-ray diffraction spectrum of a magnesiothermic reduction product, together with LiTiO₂The standard map (PDF #40-1053) is consistent. Atomic emission spectrometry of inductively coupled plasma showed that the atomic ratio of Li to Ti in the product was 0.5:1, and thus the product was Li_0.5TiO₂. FIG. 3(b) is a scanning electron micrograph thereof, Li_0.5TiO₂The particle size of the powder is about 100 nm. Mixing Li_0.5TiO₂The powder material was prepared into lithium ion experimental batteries, and FIG. 3(c) shows Li_0.5TiO₂At a current density of 0.11mA cm^-2Cycling performance under the conditions. The first charging/discharging specific capacity is 136.49/289.5mAh/g, and the specific capacity is divided after 100 times of circulationRespectively 55.1/55.6 mAh/g.

Example 3

Prepared Li₂TiO₃Weighing two samples with corresponding mass according to the molar ratio of 2:1.4 with Mg, fully grinding and mixing, placing the fully mixed samples in a corundum crucible, and then placing the corundum crucible into a tubular furnace filled with high-purity argon for heat preservation at 640 ℃ for 3 hours to carry out magnesiothermic reduction reaction. Putting the product obtained after the reaction into a dilute hydrochloric acid solution, stirring for 1h, then repeatedly washing the remainder with alcohol and deionized water, centrifuging and drying to obtain Li_0.5TiO₂And (3) powder materials.

FIG. 4(a) is an X-ray diffraction spectrum of a magnesiothermic reduction product, together with LiTiO₂The standard map (PDF #40-1053) is consistent. Atomic emission spectrometry of inductively coupled plasma showed that the atomic ratio of Li to Ti in the product was 0.5:1, and thus the product was Li_0.5TiO₂. FIG. 4(b) is Li_0.5TiO₂Scanning Electron microscope Picture of powder Material, Li_0.5TiO₂The particle size is between 100 and 200 nm. Mixing Li_0.5TiO₂The powder material was prepared into lithium ion experimental batteries, and FIG. 4(c) shows Li_0.5TiO₂At a current density of 0.11mA cm^-2Cycling performance under the conditions. The first charging/discharging specific capacity is 109.9/272.6mAh/g, and the specific capacity after 100 cycles is 58.7/59.2mAh/g respectively.

Claims

1. Preparation of Li_0.5TiO₂The method for preparing the powder material is characterized by comprising the following steps: (1) adding TiO into the mixture₂Powder and Li₂CO₃Fully grinding and uniformly mixing the powder according to the molar ratio of 1:1.05, and preserving the heat for 8 hours at 650 ℃ in a heating furnace under the protection of argon to obtain Li₂TiO₃Powder; (2) selecting magnesium powder as a reducing agent; (3) respectively weighing Li according to the molar ratio of 2: 1.05-2: 1.4₂TiO₃Powder and magnesium powder, then fully mixing the two materials uniformly; (4) transferring the uniformly mixed material into a heating furnace, preserving the heat for 3-6 hours at the temperature of 600-640 ℃ under the protection of argon, and then preserving the heatNaturally cooling to room temperature, taking out, washing in dilute hydrochloric acid, filtering and drying to obtain Li_0.5TiO₂And (3) powder materials.