CN111268703A

CN111268703A - Method for recovering lithium carbonate from waste lithium iron phosphate batteries

Info

Publication number: CN111268703A
Application number: CN202010077537.3A
Authority: CN
Inventors: 张付申; 贺凯
Original assignee: Research Center for Eco Environmental Sciences of CAS
Current assignee: Research Center for Eco Environmental Sciences of CAS
Priority date: 2019-10-10
Filing date: 2020-01-30
Publication date: 2020-06-12

Abstract

The invention relates to a method for recovering lithium carbonate from waste lithium iron phosphate batteries, and belongs to a novel solid waste recycling technology in the field of comprehensive utilization of waste resources. The method specifically comprises the steps of charging, disassembling, separating, vacuum hydrolyzing, filtering, precipitating with carbon dioxide, separating and drying, and finally obtaining the product. The method is characterized in that: the lithium carbonate powder is obtained by utilizing the characteristic of increased lithium activity in the lithiated graphite of the waste lithium iron phosphate battery and preparing lithium hydroxide through hydrolysis and preparing lithium carbonate through precipitation. Strong acid and strong base are not used in the whole recovery process, and the method has the characteristic of environmental protection.

Description

Method for recovering lithium carbonate from waste lithium iron phosphate batteries

Technical Field

The invention relates to a method for recycling lithium carbonate from waste lithium iron phosphate batteries, belongs to a novel solid waste recycling technology in the fields of environmental protection and comprehensive resource utilization, and is suitable for high-added-value recycling of lithium in the waste lithium iron phosphate batteries.

Background

Lithium ion batteries are widely used in energy storage, electric vehicles, portable electronic devices, and other fields. Energy storage systems and electric vehicles are considered to have great potential for reducing fossil energy consumption and improving the utilization rate of renewable energy, and thus have been vigorously supported by the country in recent years. In addition, with the improvement of living standard, the demand of mobile electronic devices such as mobile phones and notebook computers is increasing gradually, so that the demand of lithium ion batteries is increasing continuously. However, the service life of lithium ion batteries is generally below 8 years, and thus the number of recently reported spent lithium ion batteries is sharply increasing. China is a country with shortage of lithium resources, and lithium recovery from waste lithium ion batteries has strategic value. However, because of the low lithium content of the lithium iron phosphate battery, the lithium resource cannot be recovered from the lithium iron phosphate battery by the existing pyrometallurgical technology. The hydrometallurgical technology has higher recovery rate of lithium, however, the hydrometallurgical technology usually needs a large amount of acid and alkali, generates a large amount of waste water and has larger environmental burden.

Disclosure of Invention

The invention provides a method for recovering lithium carbonate from waste lithium iron phosphate batteries, which has high selectivity and recovery rate for recovering lithium, does not use strong acid and strong base in the whole recovery process, and has the characteristics of environmental protection.

The method for recovering lithium carbonate from waste lithium iron phosphate batteries specifically comprises the following steps:

1. charging the waste lithium iron phosphate battery to more than 80% of the battery capacity;

2. taking out the negative electrode of the charged waste lithium iron phosphate battery, and contacting the negative electrode with water in a vacuum state to obtain electrolyte and a solution of lithium hydroxide;

3. filtering the solution to remove solids to obtain a filtrate;

4. introducing carbon dioxide into the filtrate to obtain a precipitate of lithium carbonate;

5. filtering and drying the precipitate to obtain lithium carbonate powder;

6. the filtered aqueous solution was reused in the above process.

The invention is further illustrated by the following figures and embodiments in conjunction with the description.

Drawings

Fig. 1 is a process flow diagram for recovering lithium carbonate from waste lithium iron phosphate batteries.

Fig. 2X-ray diffraction pattern of lithium carbonate recovered in example 1, the peaks marked by triangles are characteristic peaks of lithium carbonate.

Detailed Description

The following examples are intended to further illustrate the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims appended hereto.

Example 1

Charging the waste lithium iron phosphate battery to 90% of the battery capacity, so that lithium ions are embedded into the graphite layer; taking out the negative electrode of the charged waste lithium iron phosphate battery, and contacting 50g of the negative electrode with 200g of water under the air pressure of 0.001MPa to obtain a solution of electrolyte and lithium hydroxide; filtering the solution to remove solids to obtain a filtrate; introducing carbon dioxide into the filtrate until the pH value is reduced to 9 to obtain a precipitate of lithium carbonate; filtering and drying the precipitate to obtain lithium carbonate powder; the filtered aqueous solution was reused in the above process.

Example 2

Charging the waste lithium iron phosphate battery to 80% of the battery capacity, so that lithium ions are embedded into the graphite layer; taking out the negative electrode of the charged waste lithium iron phosphate battery, and contacting 50g of the negative electrode with 100g of water under the air pressure of 0.001MPa to obtain an electrolyte and a solution of lithium hydroxide; filtering the solution to remove solids to obtain a filtrate; introducing carbon dioxide into the filtrate until the pH value is reduced to 9 to obtain a precipitate of lithium carbonate; filtering and drying the precipitate to obtain lithium carbonate powder; recycling the filtered water solution for the process; after the aqueous solution is recycled for 8 times, fractionating the aqueous solution to obtain distilled water and organic matters, and reusing the distilled water in the process.

Claims

1. A method for recovering lithium carbonate from waste lithium iron phosphate batteries specifically comprises the following steps:

(1) charging the waste lithium iron phosphate battery to enable lithium ions to be embedded into the graphite layer;

(2) disassembling the charged waste lithium iron phosphate battery, and separating a positive electrode and a negative electrode from a diaphragm;

(3) putting the negative electrode into deionized water under a vacuum state to obtain copper foil, graphite, electrolyte and lithium hydroxide solution;

(4) filtering the solution to remove solids to obtain a filtrate;

(5) introducing carbon dioxide into the filtrate to obtain a precipitate of lithium carbonate, and filtering and drying the precipitate to obtain lithium carbonate powder;

(6) the filtered aqueous solution is reused in the above step (3).

2. The method for recovering lithium carbonate from waste lithium iron phosphate batteries according to claim 1, wherein in the step (1), the waste lithium iron phosphate batteries are waste batteries in which graphite is used as a negative electrode material and lithium iron phosphate is used as a positive electrode material.

3. The method for recovering lithium carbonate from waste lithium iron phosphate batteries according to claim 1, wherein the vacuum state in (3) is that the air pressure is lower than 0.01 MPa.

4. The method for recovering lithium carbonate from waste lithium iron phosphate batteries according to claim 1, wherein (3) the mass ratio of the negative electrode to water is 1: 1.5-1: 4.5.

5. the method for recovering lithium carbonate from waste lithium iron phosphate batteries according to claim 1, wherein the introduction amount of the carbon dioxide in the step (5) is controlled according to the pH value of the solution, and the introduction is stopped when the pH value of the filtrate is reduced to 8-10.

6. The method for recovering lithium carbonate from waste lithium iron phosphate batteries according to claim 1, characterized in that in the step (4), when the content of organic matters in the filtered aqueous solution reaches 20% -50%, the aqueous solution is fractionated and filtered to obtain distilled water and organic matters, and the distilled water is recycled to the step (3).