CN116354408A

CN116354408A - Recycling and regenerating process of waste lithium cobalt oxide anode material

Info

Publication number: CN116354408A
Application number: CN202310330460.XA
Authority: CN
Inventors: 欧星; 龚海强; 明磊
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2023-06-30

Abstract

The invention provides a recycling process of waste lithium cobalt oxide anode materials, and belongs to the field of lithium ion battery recycling. A recycling and regenerating process of waste lithium cobalt oxide anode materials comprises the following specific processes: carrying out wet grinding reaction on waste lithium cobalt oxide anode material powder by adding a small amount of hydrochloric acid and ammonium chloride; the wet-grinding product is subjected to ammonia reduction leaching to obtain lithium-rich cobalt leaching solution; adding a proper amount of carbonate, and filtering to obtain a mixture of lithium carbonate and cobalt carbonate; and supplementing corresponding lithium salt or cobalt salt to the molar ratio of Li to Co of 1.05:1, and regenerating the lithium cobaltate anode material by a high-temperature solid-phase method. The invention damages the single crystal structure of the waste lithium cobalt oxide by means of a small amount of acid solution during ball milling, greatly strengthens the leaching rate of the subsequent ammonia leaching step, combines the ammonia leaching technology to have the characteristic of metal selective leaching, avoids impurity elements from entering the leaching liquid, realizes high-efficiency selective extraction of lithium cobalt, and greatly shortens the material regeneration flow.

Description

Recycling and regenerating process of waste lithium cobalt oxide anode material

Technical Field

The invention belongs to the field of lithium ion battery recovery, and particularly relates to a recovery and regeneration process of waste lithium cobalt oxide anode materials.

Background

Lithium cobaltate has been dominant in the lithium ion battery market due to its higher volumetric energy density and higher charge cut-off voltage. This directly causes the accumulated number of waste lithium cobaltate batteries to show a trend of explosive growth in recent years, and if the waste lithium cobaltate batteries are not strictly treated, heavy metals, toxic electrolytes and complex organic matters in the waste lithium cobaltate batteries can cause irreversible serious influence on the environment. From another perspective, the potential economic benefits of high value metals therein can effectively offset the consumption of recycling processes and even reduce the production costs of new batteries. Therefore, it is imperative to find a clean, efficient and highly adaptable way for recovering the waste lithium cobalt oxide batteries.

Hydrometallurgical technology is the currently mainstream waste battery recovery process in China. Hydrometallurgical technology generally utilizes a method of acid and reducing agent to dissolve lithium cobalt oxide and an extraction technology to realize separation and recovery of lithium cobalt, but the method has poor selectivity and needs multiple steps of impurity separation. The Chinese patent with the application number of CN106868317B discloses a recovery method of a spent lithium cobalt oxide anode material. After the spent lithium cobalt oxide anode material is separated from the aluminum foil, ferrous sulfate is used for reduction under an acidic condition, and then alkali is added to adjust the pH value to realize the fractional precipitation of iron and cobalt. The method generates a large amount of wastewater by alternately using a large amount of acid and alkali, and improves the treatment cost. The disadvantage of acid leaching is that ammonia leaching technology is promoted, and the metal ions and ammonia form a complex in alkaline solution to realize selective recovery. However, due to the single crystal structure of the waste lithium cobalt oxide anode material and the disadvantages of ammonia leaching, the leaching efficiency of cobalt is generally lower. In order to solve the problem of influence of the monocrystalline structure on the leaching efficiency, the patent proposes a method for realizing the destruction of the monocrystalline structure by utilizing wet grinding pretreatment.

The patent aims at utilizing mechanical ball milling to match with a small amount of acid reducing solution before ammonia leaching, completing the damage to the structure of the waste lithium cobalt oxide in a pre-treatment step, strengthening the selectivity and leaching rate and the upper limit of the ammonia leaching step, realizing the short-flow and high-efficiency recovery of the waste lithium cobalt oxide anode material by combining a high-temperature solid-phase method, and further improving the economic benefit of the recovery of the waste lithium cobalt oxide.

Disclosure of Invention

The invention provides a method for recovering lithium cobalt from waste lithium cobalt oxide batteries and regenerating the lithium cobalt oxide batteries into a new lithium cobalt oxide anode material. The waste is pretreated by the method of acid method reduction and mechanical ball milling to solve the problem that the leaching rate of the waste lithium cobalt oxide in the ammonia leaching step is not ideal, and the whole recycling process is shortened by combining the material regeneration step, so that the practical value of the process is proved.

The invention solves the technical problems that: aiming at the problems of longer recovery and regeneration flow and unsatisfactory ammonia leaching efficiency of lithium cobaltate in the existing process, the leaching efficiency of the ammonia leaching system on the waste lithium cobaltate is promoted by utilizing an acid reduction system and a mechanical ball milling method, so that the whole recovery and regeneration flow is shortened by utilizing the ammonia leaching method, the alternate use of reagents such as acid and alkali is reduced, and the recovery cost is reduced.

The method for efficiently recycling the waste lithium cobalt oxide anode material can be realized by the following steps:

(1) Adding a mixed solution of hydrochloric acid and ammonium chloride into waste lithium cobalt oxide anode material powder, soaking, and then placing the mixed solution in a ball milling tank for wet milling;

(2) Carrying out reduction ammonia leaching treatment on the wet-grinding product obtained in the step (1) to obtain leaching liquid rich in lithium cobalt;

(3) Adding a proper amount of carbonate into the leaching solution rich in lithium and cobalt in the step (2), and heating, concentrating and precipitating to obtain mixed precipitate of lithium carbonate and cobalt carbonate;

(4) Component measurement is carried out on the mixed precipitate obtained in the step (3), and the molar ratio of lithium to cobalt is adjusted to be 1.05:1, regenerating the lithium cobaltate anode material by using a high-temperature solid-phase synthesis method.

Further, the acid type used in the step (1) is one or more of hydrochloric acid, sulfuric acid or nitric acid, the reducing agent is one or more of ammonium sulfite and hydrogen peroxide, the pH of the mixed solution is controlled to be 1-4, and the concentration of the reducing agent is 0.5-1M.

Further, the liquid-solid ratio of the mixed solution added in the step (1) to the waste lithium cobaltate powder is 0.5-2 ml:1g, and the ball milling time is 2-6 h.

Further, in the step (2), the main body of the leaching agent is ammonia water, buffer salt is one or more of ammonium carbonate, ammonium bicarbonate, ammonium sulfate and ammonium chloride, the reducing agent is one or more of sodium sulfite, ammonium sulfite and hydrogen peroxide, the pH is controlled to be 9-10, the concentration of the reducing agent is 0.5-1M, the concentration of the buffer salt is 0.5-1M, the temperature is controlled to be 60-80 ℃, the leaching time is 2-4 h, and the liquid-solid ratio of the leaching agent to waste is 40-60 mL:1g.

Further, the carbonate added in step (3) is one or more of sodium carbonate and ammonium carbonate.

Further, the molar ratio of lithium cobalt in step (4) is 1.05:1, the calcination temperature is 600-900 ℃ and the calcination time is 3-9 h.

The invention has the beneficial effects that: the patent designs an acid reduction wet ball milling process, which is used for preprocessing waste lithium cobaltate materials, and damages to a lithium cobaltate monocrystal structure are realized through reducing partial cobalt valence states, so that the leaching efficiency of cobalt in the subsequent ammonia leaching process is improved. And then the alkaline condition of the solution after ammonia leaching is further utilized to directly concentrate and precipitate, so that the recovery and regeneration flow is shortened. Compared with the prior art, the method has the advantages that selective extraction of lithium cobalt by an ammonia method is realized, the problem of non-ideal leaching efficiency of ammonia leaching on cobalt is solved, the recovery and regeneration process is further shortened, and the economic benefit is better.

Drawings

FIG. 1 is a view showing the breakage of single crystals after mechanical ball milling by acid reduction according to the present invention

FIG. 2 is a graph showing the cycle performance of regenerated lithium cobaltate

Detailed Description

Example 1

And (3) putting a plurality of waste lithium cobalt oxide batteries into 0.1M NaCl solution for discharging, disassembling the batteries after discharging is completed, and collecting waste lithium cobalt oxide anode materials. 3g of waste lithium cobalt oxide positive electrode material is added with 3mL of pH value 1, H ₂ O ₂ HCl solution with concentration of 1M was wet milled in a ball milling tank for 2 h. Pouring the liquid-solid mixture after wet grinding into a three-necked flask, adding 100mL of leaching agent with the ammonium chloride concentration of 0.5M, the hydrogen peroxide concentration of 1M and the pH of about 9, controlling the temperature to be 70 ℃, leaching for 2 hours, and filtering to obtain leaching liquid rich in lithium cobalt. The leaching solution is placed in a water bath kettle to be heated to 80 ℃, and sodium carbonate is gradually added to be saturated. Filtering to obtain mixed precipitate of lithium and cobalt, oven drying, grinding and mixing.

Taking a small amount of mixed precipitate for digestion, detecting specific ion concentration by an Inductively Coupled Plasma (ICP) spectrometer, and adding the mixed precipitate according to the proportion of lithium and cobaltThe corresponding lithium cobalt carbonate is prepared by adjusting the molar ratio of lithium cobalt to 1.05-1, then placing the lithium cobalt carbonate in a muffle furnace and calcining the lithium cobalt carbonate at 800 ℃ for 6 hours to obtain LiCoO ₂ And a positive electrode material.

Example 2

And (3) putting a plurality of waste lithium cobalt oxide batteries into 0.1M NaCl solution for discharging, disassembling the batteries after discharging is completed, and collecting waste lithium cobalt oxide anode materials. Adding 4mL of waste lithium cobalt oxide positive electrode material with pH value of 1 and H into the mixture ₂ O ₂ HCl solution with concentration of 0.5M was wet milled in a ball milling tank for 3 h. Pouring the wet-ground liquid-solid mixture into a three-necked flask, adding 250mL of leaching agent with the concentration of ammonium chloride of 1M, the concentration of hydrogen peroxide of 1M and the pH of about 9, controlling the temperature to be 80 ℃, leaching for 2h, and filtering to obtain leaching liquid rich in lithium cobalt. The leaching solution is placed in a water bath kettle to be heated to 80 ℃, and sodium carbonate is gradually added to be saturated. Filtering to obtain mixed precipitate of lithium and cobalt, oven drying, grinding and mixing.

Taking a small amount of mixed precipitate for digestion, detecting specific ion concentration by an Inductively Coupled Plasma (ICP) spectrometer, adding corresponding lithium cobalt carbonate according to the proportion of lithium cobalt, adjusting the molar ratio of lithium cobalt to 1.05-1, and then placing the mixed precipitate in a muffle furnace for calcination for 9 hours at 850 ℃ to obtain LiCoO ₂ And a positive electrode material.

Claims

1. The recovery and regeneration process of the waste lithium cobalt oxide anode material is characterized by comprising the following steps of:

2. The method for efficiently regenerating the waste lithium cobalt oxide anode material into the new lithium cobalt oxide anode material according to claim 1, wherein in the step (1), the acid is one or more of hydrochloric acid, sulfuric acid or nitric acid, the reducing agent is ammonia sulfite, the hydrogen peroxide is one or more of hydrogen peroxide, the pH of the mixed solution is controlled to be 1-4, the concentration of the reducing agent is 0.5-1M, and the liquid-solid ratio of the added mixed solution to the waste lithium cobalt oxide powder is 0.5-2 ml:1g, and the ball milling time is 2-6 h.

3. The method for efficiently regenerating the waste lithium cobalt oxide anode material into the new lithium cobalt oxide anode material according to any one of claims 1-2, wherein the main leaching agent in the step (2) is ammonia water, buffer salt is one or more of ammonium carbonate, ammonium bicarbonate, ammonium sulfate and ammonium chloride, the reducing agent is one or more of sodium sulfite, ammonium sulfite and hydrogen peroxide, the pH is controlled to be 9-10, the concentration of the reducing agent is 0.5-1M, the concentration of buffer salt is 0.5-1M, the temperature is controlled to be 60-80 ℃, the leaching time is 2-4 h, and the liquid-solid ratio of the leaching agent to waste is 40-60 mL:1g.

4. The method for efficiently regenerating a waste lithium cobalt oxide positive electrode material into a new lithium cobalt oxide positive electrode material according to any one of claims 1 to 3, wherein the carbonate added in the step (3) is one or more of sodium carbonate and ammonium carbonate.

5. The method for efficiently regenerating a waste lithium cobalt oxide positive electrode material into a new lithium cobalt oxide positive electrode material according to any one of claims 1 to 4, wherein the calcining temperature in the step (4) is 600 to 900 ℃ and the calcining time is 3 to 9 hours.