CN1257572C - Method for preparing nano-cobalt oxide from waste lithium-ion batteries - Google Patents

Abstract

The present invention discloses a method for recovering and preparing nano cobalt oxide from a waste lithium ion battery, which belongs to chemical separation and the preparation technique of inorganic nano powder. The method comprises the following steps that a battery is cut to separate an anode material, and the anode material is sheared into small fragments; Al foil is soaked by excess NaOH at room temperature, and filter residue which is obtained by reaction and filtration is a mixture containing LiCoO2; the mixture is dissolved by HNO3 at the room temperature and is filtered to obtain nitrate solution containing Co<2+> and Li<1+>; the nitrate solution drops into the NaOH solution and pH is regulated to 9 to 11 to obtain a blue minute Co (OH) 2 deposit; the blue minute Co (OH) 2 deposit is converted into hydration cobalt oxide, and impurity ion in the hydration cobalt oxide is removed by filtration and wash; CoO (OH) is dried by an infrared lamp, and then, is heated for 2h at the temperature of 400 to 600 DEG C so as to obtain average grains and the Co3O4 nano powder. The present invention has the advantages of simple preparation processes of the method, easy operation, easy processing of different waste liquid, high purity of the obtained Co3O4 nano powder, and high specific surface area.

Description

Method for preparing nano-cobalt oxide from waste lithium-ion batteries

                      

The invention relates to a method for recovering and preparing nano-cobalt oxide from discarded lithium-ion batteries, which belongs to the technology of chemical separation and preparation of inorganic nano-powder.

Background technique

The positive electrode material of lithium ion battery is made of active material LiCoO ₂ , carbon black, acetylene black, and binder adhered to the aluminum foil in a certain proportion. The content of each part of the positive electrode material is shown in Table 1:

Table 1 Composition of cathode materials for lithium-ion batteries substance _LiCoO2 carbon black, acetylene black binder aluminum foil Content (wt.%) 76.80 9.03 4.52 9.65

The disposal of scrapped lithium-ion batteries usually faces the following problems: First, the surfaces of the positive and negative electrodes of scrapped lithium-ion batteries usually contain a small amount of elemental lithium. Since metallic lithium in the elemental state is highly flammable and explosive, This is a safety issue that requires special attention in battery disposal; in addition, cobalt is a heavy metal that can be harmful to the environment if not handled properly. Therefore, the reasonable disposal of scrap lithium-ion batteries is of great significance to protect the environment.

At present, important progress has been made in the research work on the recovery of lithium-ion secondary batteries abroad. Sony Corporation of Japan has cooperated with Sumitomo Metal Mining Co., Ltd. to research and develop the technology of recovering cobalt from waste lithium-ion secondary batteries. Incinerate the battery first to remove organic matter, then screen, remove iron and copper, heat the residual powder and dissolve it in acid, and extract it with an organic solvent to extract cobalt oxide. This product can be used as a raw material for pigments and coatings industries. . However, the above methods still have certain deficiencies: first, the method of incineration to remove organic matter needs to be equipped with flue gas purification equipment, otherwise it is easy to cause air pollution; in addition, under heating conditions, the "residual powder" is dissolved with hydrochloric acid to prevent corrosion of the equipment The requirements are high and the operating environment is harsh.

Contents of Invention

The purpose of the invention is to reclaim and prepare nano cobalt oxide from discarded lithium ion batteries. The process of the method is simple, and the prepared cobalt oxide powder has high purity, an average particle size of less than 100 nanometers and a large specific surface area.

The present invention is achieved through the following technical solutions: a method for reclaiming and preparing nano-cobalt oxide from waste lithium-ion batteries, which is characterized in comprising the following steps:

(1) Cutting of battery

Cut the battery in water to separate the positive electrode material from other components, and cut the positive electrode material into small pieces;

(2) Under room temperature, adopt the excess NaOH alkali that mass concentration is 20%～60% to soak described small fragment, react until not seeing to produce bubble till, filter, and filtrate is collected and stays for other usefulness, filter residue is infrared Dry it under the lamp, then grind it into powder, pass through an 80-mesh sieve, dissolve it again with lye of the same concentration and ratio, and filter it. The obtained filter residue is a mixture containing LiCoO ₂ ;

(3) At room temperature, use _HNO3 with a mass concentration of 10% to 50% to dissolve the mixture, filter, and the solution obtained is a nitrate solution containing Co ²⁺ , Li ⁺ , and the addition of nitric acid is more than that according to Co (NO ₃ ) ₂ +LiNO ₃ The amount of HNO ₃ calculated from the stoichiometric dose ratio;

(4) Add the above-mentioned nitrate solution dropwise to a NaOH solution with a mass concentration of 10% to 60%, adjust the pH to 9 to 11, and obtain blue fine Co(OH) ₂ precipitates, Co(OH) ₂ precipitates Unstable in the air, immediately transform into brown-black hydrated cobalt oxide CoO(OH), filter, wash the filtrate with deionized water several times to eliminate impurity ions, save the filtrate and cleaning liquid for recovery The use of lithium element;

(5) CoO(OH) is dried under an infrared lamp, and then heat-treated at 400-600° C. for 2 hours to obtain an ultrafine Co ₃ O ₄ powder with an average particle size of less than 100 nm.

The invention has the advantages that the preparation process is simple and feasible, the specific surface area of the prepared Co ₃ O ₄ powder is 90-110m ² /g, the average particle diameter of the powder is less than 100nm, the purity reaches more than 99.5%, and the recovery rate is 85% above.

Specific implementation plan

example 1.

Take 10 batteries with a single weight of 28g, cut the battery in water, separate the positive electrode material from other components, cut the positive electrode material into pieces smaller than 2cm×2cm in size, put these pieces into 500ml at room temperature, mass In NaOH solution with a concentration of 40%, react until no bubbles are seen, filter, collect the filtrate for other purposes, dry the filter residue under infrared light, then grind it into powder, pass through an 80-mesh sieve, and use the same Dissolve the lye with the concentration and ratio once, filter it, and the obtained filter residue is a mixture containing LiCoO ₂ ; at room temperature, use 400ml of HNO ₃ solution with a mass concentration of 30% to dissolve the mixture, filter it, and the obtained solution is Co ^{2 +} , Li ⁺ nitrate solution; the above nitrate solution was added dropwise to 400ml of NaOH solution with a mass concentration of 30%, and the pH was adjusted to 9-11 to obtain blue fine Co(OH) ₂ precipitates, Co The (OH) ₂ precipitate is unstable in the air, and immediately converts into brown-black hydrated cobalt oxide CoO(OH), filters, and washes the filtrate with deionized water multiple times (more than three times of cleaning is required) to eliminate impurity ions therein; CoO(OH) was dried under an infrared lamp, and then heat-treated at 500°C for 2 hours to obtain Co ₃ O ₄ nanopowder. The product was weighed, and the weight of the obtained Co ₃ O ₄ nanopowder was 41g. The calculation of the theoretical content of these components shows that in 10 batteries with a unit weight of 28g, the theoretical weight of Co ₃ O ₄ that can be recovered is about 47.8g. It can be seen that the recovery rate of Co ₃ O ₄ recovered by this process is was 85.8%.

Example 2

Take 10 batteries with a single weight of 28g, cut the battery in water, separate the positive electrode material from other parts, cut the positive electrode material into pieces smaller than 2cm×2cm in size, put these pieces into 800ml at room temperature, mass Concentration is 20% NaOH solution, react until no bubbles can be seen, filter, collect the filtrate for other use, dry the filter residue under infrared lamp, then grind it into powder, pass through 80 mesh sieve, and use the same Concentration and proportion of lye dissolved once, filtered, the obtained filter residue is a mixture containing _LiCoO2 ; at room temperature, use 800ml, _HNO3 solution with a mass concentration of 20% to dissolve the mixture, filtered, the obtained solution is ^{Co2 +} , Li ⁺ nitrate solution; the above nitrate solution was added dropwise to 500ml of NaOH solution with a mass concentration of 20%, and the pH was adjusted to 9-11 to obtain blue fine Co(OH) ₂ precipitates, Co The (OH) ₂ precipitate is unstable in the air, and immediately converts into brown-black hydrated cobalt oxide CoO(OH), filters, and washes the filtrate with deionized water multiple times (more than three times of cleaning is required) to eliminate impurity ions therein; CoO(OH) was dried under infrared lamps, and then heat-treated at 600°C for 2 hours to obtain Co ₃ O ₄ nanopowder. The product was weighed, and the weight of the obtained Co ₃ O ₄ nanopowder was 39.5g. The theoretical content calculation of various components shows that in 10 batteries with a unit weight of 28g, the theoretical weight of Co ₃ O ₄ available for recovery is about 47.8g. It can be seen that the recovery of Co ₃ O ₄ by this process The rate is 82.6%.

Claims (1)

1. A method for reclaiming and preparing nano-cobalt oxide from waste lithium-ion batteries, characterized in that it comprises the following steps: (1) Cutting of battery Cut the battery in water to separate the positive electrode material from other components, and cut the positive electrode material into small pieces; (2) Under room temperature, adopt the excess NaOH alkali that mass concentration is 20%～60% to soak described small fragment, react until not seeing to produce bubble till, filter, and filtrate is collected and stays for other usefulness, filter residue is infrared Dry it under the lamp, then grind it into powder, pass through an 80-mesh sieve, dissolve it again with lye of the same concentration and ratio, and filter it. The obtained filter residue is a mixture containing LiCoO ₂ ; (3) At room temperature, use _HNO3 with a mass concentration of 10% to 50% to dissolve the mixture, filter, and the solution obtained is a nitrate solution containing Co ²⁺ , Li ⁺ , and the addition of nitric acid is more than that according to Co (NO ₃ ) ₂ +LiNO ₃ The amount of HNO ₃ calculated from the stoichiometric dose ratio; (4) Add the above-mentioned nitrate solution dropwise to a NaOH solution with a mass concentration of 10% to 60%, adjust the pH to 9 to 11, and obtain blue fine Co(OH) ₂ precipitates, Co(OH) ₂ precipitates Unstable in the air, immediately transform into brown-black hydrated cobalt oxide CoO(OH), filter, wash the filtrate with deionized water several times to eliminate impurity ions, save the filtrate and cleaning liquid for recovery The use of lithium element; (5) CoO(OH) is dried under an infrared lamp, and then heat-treated at 400-600° C. for 2 hours to obtain an ultrafine Co ₃ O ₄ powder with an average particle size of less than 100 nm.