CN108360022A - A kind of method that melten salt electriochemistry method recycles cobalt element in anode material of lithium battery - Google Patents

Abstract

The invention discloses a method for recovering cobalt element in lithium battery cathode material by molten salt electrochemical method, which belongs to the technical field of transition metal element recovery and reuse. The method is as follows: 1) disassemble the lithium battery after discharge, crush the positive electrode material, add the leachate, stir at 50-80°C for 10-60 minutes, and filter; 2) add NaOH aqueous solution dropwise to the filtrate, when the pH is 4.7-8, Filtration; add NaOH aqueous solution dropwise to the primary filtrate, when the pH is 9.2 to 10.0, filter with suction to obtain a precipitate, dry, grind, press, and burn to obtain an electrode tablet; 3) Wrap the cobalt oxide electrode tablet with foamed nickel The cathode is connected with the molybdenum wire, and the anode is connected with the graphite rod and the stainless steel wire; 4) The molten salt raw material is heated to the melting temperature, the cathode and the anode are inserted into the molten salt, a voltage is applied, and after electrolysis, the cathode is taken out, cooled, and cleaned by ultrasonic oscillation. Get cobalt. The method for recovering the cobalt element in the positive electrode material of the waste lithium battery has the advantages of low cost, high efficiency and simple operation.

Description

A method for recovering cobalt element in lithium battery positive electrode material by molten salt electrochemical method

technical field

The invention relates to the technical field of recovery and reuse of transition metal elements in positive electrode materials in waste lithium batteries, in particular to a method for recovering cobalt elements in lithium battery positive electrode materials by a molten salt electrochemical method.

Background technique

Compared with traditional battery technology, lithium batteries charge faster and last longer, so lithium-ion batteries have a bright future. According to relevant statistics, lithium-ion batteries account for at least 70% of the batteries used in mobile phones. In 2015, the global mobile phone users have exceeded 5.2 billion, and the number of users will continue to expand in the future. With the advent of high-tech products such as tablet computers and Popularity, the application of lithium-ion batteries will also have a larger potential market. In addition, the number of electric vehicles continues to increase, and the demand for lithium batteries will continue to grow. With the extensive use of lithium batteries, the recycling of batteries is urgent. Cobalt is an important scarce element that constitutes the cathode material of lithium batteries. Efficient recycling of cobalt can not only avoid the waste of resources, but also reduce its pollution and harm to the environment, which meets the requirements of sustainable development. Combined with the storage situation of global cobalt resources, making full use of cobalt resources is necessary for the sustainable development of batteries. The existing process of recovering metal elements such as nickel, manganese, and cobalt in the positive electrode material of the battery through electrolysis in the solution will produce a large amount of waste water containing heavy metal ions during actual operation, which will pollute the environment. The realization of electrolysis is more friendly to the environment.

Contents of the invention

The purpose of the present invention is to provide a method for recycling the cobalt element in the positive electrode material of the lithium battery by the molten salt electrochemical method. The cobalt oxide produced by recycling the battery is wrapped with the foamed nickel current collector and connected with the molybdenum wire to form a cathode, a graphite rod and a molybdenum wire. The stainless steel wire current collector is connected to make anode electrolysis to obtain metal cobalt. In chloride or carbonate molten salt, at high temperature (the specific temperature depends on the composition of the molten salt), apply voltage for electrolysis for a period of time to reduce cobalt oxide to obtain metal cobalt. The component is lifted from the molten salt for cooling, ultrasonically oscillated in water to remove the salt, and dried to realize electrolysis and recovery of cobalt in the molten salt environment. Adopting the method of the invention to recover the cobalt element in the positive electrode material of the waste lithium battery has the advantages of low cost, high efficiency and simple operation.

A kind of molten salt electrochemical method of the present invention reclaims the method for cobalt element in lithium battery cathode material, carries out according to the following steps:

Step 1: Dissolution of Lithium Battery Cathode Material

(1) After the lithium battery is discharged, it is disassembled and separated to obtain the positive electrode material and the negative electrode material of the lithium battery;

(2) After pulverizing the positive electrode material of the lithium battery, add the leaching solution, and heat at a constant temperature of 50-80°C for 10-60 minutes while stirring to obtain a leaching mixture;

Among them, according to the solid-liquid ratio, lithium battery positive electrode material: leachate = (0.5 ~ 1) g: (5 ~ 20) mL;

The leaching solution is a mixed aqueous solution of _H2SO4 with a molar concentration of _2-6mol /L and _H2O2 with a volume percentage of 20-40%. According to _the volume ratio, the molar concentration is _2-6mol / _LH2SO4 : volume percentage 20-40% H ₂ O ₂ =(3-5):1;

(3) filtering the leaching mixture to obtain a filtrate;

Step 2: Preparation of cobalt oxide electrode pellets

(1) Add dropwise an aqueous NaOH solution with a molar concentration of 1 to 3 mol/L in the filtrate. When the pH value is 4.7 to 8, precipitates formed by Fe and Al will precipitate out. Filter to remove the precipitates formed by Fe and Al to obtain a filtrate;

(2) In the primary filtrate, continue to dropwise add the NaOH aqueous solution whose molar concentration is 1～3mol/L, when the pH value is 9.2～10.0, the precipitate formed by Co is separated out, and suction filtration is carried out to obtain Co(OH) _Precipitate ;

(3) Co(OH) ₂ is precipitated and dried, ground into powder, pressed into tablets, and burned in air to obtain cobalt oxide electrode tablets;

Step 3: Electrochemical Preparation

Wrap the cobalt oxide electrode sheet with a nickel foam current collector, and then connect it with a molybdenum wire as a cathode, and connect a graphite rod with a stainless steel wire collector as an anode;

Dry the molten salt raw material to remove moisture, place it in a crucible, then put the crucible into the reactor, hang the cathode and anode above the molten salt raw material, close the reactor, and continuously feed argon gas into the reactor to form argon gas atmosphere;

Step 4: Electrolysis

(1) Heat the molten salt raw material to the melting temperature to form a molten salt. Insert the cathode and anode into the molten salt to form a two-electrode system. Apply voltage to the two electrodes to perform electrolysis. After the electrolysis is completed, take out the electrolyzed cathode and cool it down. , and insert another cathode to apply voltage to continue electrolysis; wherein, the horizontal distance between cathode and anode is 15±5mm, the applied voltage is 2.0-2.1V, and the electrolysis time is 8-12h;

(2) Put the cooled cathode after electrolysis into water, and clean it with ultrasonic vibration to remove the salt attached to the surface of the cathode, and the obtained cathode is cobalt.

In (1) of the above-mentioned step 1, the discharge treatment specifically includes: using a charge-discharge instrument to perform discharge treatment, discharge at a constant current of 3A, and discharge time ≥ 30min.

In (2) of the step 1, the lithium battery cathode material is pulverized, and after pulverization, the particle size of the lithium battery cathode material is D97.

In (3) of the step 2, the drying is at 90-100° C. for 500-600 minutes in air.

In (3) of the step 2, the grinding is to obtain Co(OH) ₂ powder with a particle size of 0.10-0.20 mm.

In (3) of the step 2, the tableting is carried out by weighing 2.0g Co(OH) _powder .

In (3) of step 2, the burning is burning in air at 900-1000° C. for 1-24 hours.

In the step 3, the graphite rods can also be SnO ₂ ceramics or Ni-based alloys.

In the step 3, the molten salt raw material is one or a mixture of chloride molten salt raw materials, carbonate molten salt raw materials, and hydroxide molten salt raw materials;

When it is a chloride molten salt raw material, it is specifically a mixed molten salt of one or more of CaCl ₂ , LiCl, NaCl, KCl, MgCl ₂ , and BaCl ₂ ;

When it is a carbonate molten salt raw material, it is specifically a mixed molten salt of one or more of Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , and CaCO ₃ ;

When it is a hydroxide molten salt raw material, it is specifically one or more mixed molten salts of LiOH, NaOH, and KOH.

In the step 3, the argon gas is introduced through the inlet of the reactor and discharged from the gas outlet of the reactor. When discharged, the moisture generated by the molten salt is taken away.

In the step 4, in the ultrasonic vibration cleaning, the cleaning water is weakly acidic water with 5≤pH≤7.

In the step 4, the ultrasonic vibration cleaning has an ultrasonic frequency of 0.5kHZ-100kHZ.

A kind of molten salt electrochemical method of the present invention reclaims the method for cobalt element in lithium battery cathode material, and its beneficial effect is:

1. Lithium battery recycling is mainly to recover metal elements such as nickel, manganese, and cobalt in the positive electrode material of lithium batteries. The invention recovers the cobalt element in the positive electrode material of the lithium battery by adopting an electrochemical method in molten salt. Firstly, the cobalt in the positive electrode material of the battery is extracted in the form of hydroxide (Co(OH) ₂ ), and then the Co(OH) ₂ is burned to prepare cobalt oxide, which is pressed into tablets and connected with the foamed nickel current collector to make a cathode 1. Graphite rods are connected with stainless steel wire collectors to make anodes, and the metal cobalt is obtained by electrolysis in molten salt.

2. In the present invention, the reclaimed cobalt oxide, nickel foam and molybdenum wire are used as the cathode, and the graphite rod and the stainless steel wire collector are connected to form an anode, which is electrolyzed in a molten salt environment, and the cathode generates metallic cobalt during electrolysis, and the anode is made Oxygen or carbon dioxide will not harm the environment and will provide assistance for the recycling of lithium batteries in our country.

3. The technical invention has low cost, easy operation, and environmental friendliness, and can efficiently recover the cobalt element in the lithium battery of the mobile phone.

Description of drawings

Figure 1 is a schematic diagram of the electrolysis device of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with embodiment.

In the following examples, unless otherwise specified, the equipment and raw materials used are commercially available, and the purity is analytically pure or above.

Example 1

A kind of molten salt electrochemical method reclaims the method for cobalt element in lithium battery cathode material, carries out according to the following steps:

Step 1: Dissolution of Lithium Battery Cathode Material

(1) Discharge the recovered lithium battery using a charge-discharge instrument, discharge at a constant current of 3A, and discharge for 30 minutes, then manually disassemble the battery to separate and obtain the positive and negative materials of the lithium battery;

(2) After crushing the positive electrode material of the lithium battery, add the leaching solution, heat at a constant temperature of 70°C for 30 minutes, and at the same time stir to obtain the leaching mixture; wherein, according to the solid-to-liquid ratio, the positive electrode material of the lithium battery: leaching solution = 1g: 10mL; the leaching solution is The molar concentration is 4mol/L, the mixed solution of H ₂ SO ₄ and 30% H ₂ O ₂ by volume, according to the volume ratio, the molar concentration is 4 mol/L H ₂ SO ₄ : 30% H ₂ O ₂ by volume =5:1;

(3) filtering the leaching mixture to obtain a filtrate;

Step 2: Preparation of cobalt oxide electrode pellets

(1) dripping the NaOH aqueous solution that molar concentration is 2mol/L in the filtrate, when pH value is 6.47, the precipitation that has Fe, Al formation is separated out, filters, and removes the precipitation that Fe, Al formation, obtains primary filtrate;

(2) continue dripping the NaOH aqueous solution that molar concentration is 2mol/L in primary filtrate, when pH value is 10, the precipitation that Co forms is separated out, carries out suction filtration, obtains Co(OH) _Precipitate ;

(3) Dry the Co(OH) ₂ precipitate at 90°C for 560 minutes, grind it into a powder with a particle size of 0.1mm, take 2.0g of Co(OH) ₂ powder, press it into tablets, and burn it at 1000°C for 5 hours in the air to obtain the oxidized Cobalt electrode pellets;

Step 3: Electrochemical Preparation

Wrap the cobalt oxide electrode sheet with a nickel foam current collector, and then connect it with a molybdenum wire as a cathode, and connect a graphite rod with a stainless steel wire collector as an anode;

Dry the molten salt raw material _CaCl2 to remove moisture, place it in a crucible, then put the crucible into the reactor, hang the cathode and anode above the molten salt raw material, close the reactor, and feed the reactor through the air inlet on the reactor. The argon gas is continuously fed into the reactor, and the gas outlet is discharged to form an argon atmosphere in the reactor. The schematic diagram of the electrolysis device is shown in Figure 1;

Step 4: Electrolysis

(1) The molten salt raw material _CaCl2 is heated to the melting temperature to form a molten salt, and the moisture generated during the heating process is taken away by the argon; the cathode and the anode are inserted into the molten salt to form a two-electrode system, and a voltage is applied to the two electrodes, Carry out electrolysis. After the electrolysis is completed, take out the electrolyzed cathode, cool it, and insert another cathode to apply voltage to continue electrolysis; wherein, the horizontal distance between the cathode and the anode is 15mm, the applied voltage is 2.0V, and the constant cell pressure electrolysis time for 10h;

(2) Put the cooled cathode after electrolysis into weakly acidic clear water with a pH value of 6.5, and clean it with an ultrasonic frequency of 50kHZ ultrasonic oscillation to remove the salt attached to the surface of the cathode, and the obtained cathode is cobalt.

Example 2

A kind of molten salt electrochemical method reclaims the method for cobalt element in lithium battery cathode material, carries out according to the following steps:

Step 1: Dissolution of Lithium Battery Cathode Material

(1) Discharge the recovered lithium battery using a charge-discharge instrument, discharge at a constant current of 3A, and discharge for 40 minutes, then manually disassemble the battery to separate and obtain the positive and negative materials of the lithium battery;

(2) After pulverizing the positive electrode material of lithium battery, add leachate, heat at 50°C for 60 minutes at a constant temperature, and at the same time stir to obtain the leach mixture; wherein, according to the solid-to-liquid ratio, lithium battery positive electrode material: leachate = 0.5g: 5mL; leachate It is a mixture of H ₂ SO ₄ and 40% H ₂ O ₂ with a molar concentration of 6 mol/L, and the molar concentration is 6 mol/L H ₂ SO ₄ : 40% H ₂ O by volume ₂ = 3:1;

(3) filtering the leaching mixture to obtain a filtrate;

Step 2: Preparation of cobalt oxide electrode pellets

(1) dripping the NaOH aqueous solution that molar concentration is 1mol/L in the filtrate, when pH value is 4.7, the precipitation that has Fe, Al formation is separated out, filters, and removes the precipitation that Fe, Al formation, obtains primary filtrate;

(2) continue dripping the NaOH aqueous solution that molar concentration is 1mol/L in the primary filtrate, when the pH value is 9.2, the precipitation that Co forms is separated out, carries out suction filtration, obtains Co(OH) _Precipitate ;

(3) Dry the Co(OH) ₂ precipitate at 100°C for 500min, grind it into a powder with a particle size of 0.2mm, take 2.0g of Co(OH) ₂ powder, press it into tablets, and burn it at 900°C for 10h in the air to obtain the oxidized Cobalt electrode pellets;

Step 3: Electrochemical Preparation

With embodiment 1, difference is:

(1) In step 3, the _SnO2 ceramic is connected with the stainless steel wire current collector as the anode.

(2) In step 3, the molten salt raw material is Li ₂ CO ₃ .

Step 4: Electrolysis

With embodiment 1, difference is:

(1) In step 4, the horizontal distance between the cathode and the anode is 16mm, the applied voltage is 2.1V, and the constant cell voltage electrolysis time is 8h;

(2) In step 4, ultrasonic vibration cleaning is performed, the cleaning water is weakly acidic water with a pH of 7, and the ultrasonic frequency is 10kHZ.

Other methods are the same.

Example 3

A kind of molten salt electrochemical method reclaims the method for cobalt element in lithium battery cathode material, carries out according to the following steps:

Step 1: Dissolution of Lithium Battery Cathode Material

(1) Discharge the recovered lithium battery using a charge-discharge instrument, discharge at a constant current of 3A, and discharge for 60 minutes, then manually disassemble the battery to separate and obtain the positive and negative materials of the lithium battery;

(2) After crushing the positive electrode material of the lithium battery, add the leaching solution, heat at a constant temperature of 80°C for 10 minutes, and at the same time stir to obtain the leaching mixture; wherein, according to the solid-to-liquid ratio, the positive electrode material of the lithium battery: leaching solution = 1g: 20mL; the leaching solution is The molar concentration is 2mol/L, the mixed solution of H ₂ SO ₄ and 20% H ₂ O ₂ by volume, the molar concentration is 2 mol/L H ₂ SO ₄ : 20% H ₂ O ₂ by volume =4:1;

(3) filtering the leaching mixture to obtain a filtrate;

Step 2: Preparation of cobalt oxide electrode pellets

(1) dripping the NaOH aqueous solution that molar concentration is 3mol/L in the filtrate, when the pH value is 8, have the precipitation that Fe, Al form to separate out, filter, remove the precipitation that Fe, Al form, obtain primary filtrate;

(2) continue dripping the NaOH aqueous solution that molar concentration is 3mol/L in the primary filtrate, when the pH value is 10, the precipitation that Co forms is separated out, carries out suction filtration, obtains Co(OH) _Precipitate ;

(3) Dry the Co(OH) ₂ precipitate at 100°C for 600 minutes, grind it into a powder with a particle size of 0.1mm, take 2.0g of Co(OH) ₂ powder, press it into tablets, and burn it at 1000°C for 5 hours in the air to obtain the oxide Cobalt electrode pellets;

Step 3: Electrochemical Preparation

With embodiment 1, difference is:

(1) In step 3, the Ni-based alloy is connected to the stainless steel wire current collector as an anode.

(2) In step 3, the molten salt raw material is NaOH.

Step 4: Electrolysis

With embodiment 1, difference is:

(1) In step 4, the horizontal distance between the cathode and the anode is 20mm, the applied voltage is 2.0V, and the constant cell voltage electrolysis time is 12h;

(2) In step 4, ultrasonic vibration cleaning is performed, the cleaning water is weakly acidic water with a pH of 5, and the ultrasonic frequency is 5kHZ.

Other methods are the same.

Example 4

A method for recycling the cobalt element in the lithium battery positive electrode material by molten salt electrochemical method, the same as embodiment 1, the difference is:

Step 3: Preparation for Electrolysis

(1) In step 3, the Ni-based alloy is connected to the stainless steel wire current collector as an anode.

(2) In step 3, the molten salt raw materials are Na ₂ CO ₃ and K ₂ CO ₃ , and the mass ratio of the two is 1:1.

Step 4: Electrolysis

With embodiment 1, difference is:

(1) In step 4, the horizontal distance between the cathode and the anode is 10mm, the applied voltage is 2.0V, and the constant cell voltage electrolysis time is 10h;

(2) In step 4, ultrasonic vibration cleaning is performed, the cleaning water is weakly acidic water with a pH of 6, and the ultrasonic frequency is 100kHZ.

Other methods are the same.

Example 5

A method for recycling the cobalt element in the lithium battery positive electrode material by molten salt electrochemical method, the same as embodiment 1, the difference is:

(1) In step 3, the molten salt raw materials are _CaCl and LiCl, and the atomic number ratio of the two is Li: Ca=0.65:0.35.

Other methods are the same.

Example 6

A method for recycling the cobalt element in the lithium battery positive electrode material by molten salt electrochemical method, the same as embodiment 1, the difference is:

(1) In step 3, the molten salt raw materials are MgCl ₂ and Na ₂ CO ₃ , and the mass ratio of the two is 1:1.

Other methods are the same.

Claims (10)

1. a kind of method of cobalt element in melten salt electriochemistry method recycling anode material of lithium battery, which is characterized in that according to the following steps It carries out：

Step 1：The dissolving of anode material of lithium battery

(1) it after lithium battery being carried out discharge treatment, is disassembled, isolated anode material of lithium battery and negative material；

(2) after crushing anode material of lithium battery, leachate is added, in 50~80 DEG C of 10~60min of heated at constant temperature, and meanwhile it is adjoint Stirring obtains leaching mixed liquor；

Wherein, by solid-to-liquid ratio, anode material of lithium battery：Leachate=(0.5~1) g:(5~20) mL；

Leachate is the H that molar concentration is 2~6mol/L₂SO₄The H for being 20~40% with percentage by volume₂O₂Mixed aqueous solution, By volume, molar concentration is 2~6mol/LH₂SO₄：The H that percentage by volume is 20~40%₂O₂=(3~5):1；

(3) mixed liquor will be leached to be filtered, obtains filtrate；

Step 2：The preparation of cobalt oxide electrode tabletting

(1) the NaOH aqueous solutions that molar concentration is 1~3mol/L are added dropwise into filtrate, when pH value is 4.7~8, there is Fe, Al shape At Precipitation, filtering, removal Fe, Al formed precipitation, obtain first-time filtrate；

(2) continue that the NaOH aqueous solutions that molar concentration is 1~3mol/L are added dropwise into first-time filtrate, when pH value is 9.2~10.0 When, the Precipitation that Co is formed is filtered, obtains Co (OH)₂Precipitation；

(3) by Co (OH)₂Precipitation drying, grind into powder, tabletting, in air calcination obtain cobalt oxide electrode tabletting；

Step 3：Electrochemistry prepares

Cobalt oxide electrode tabletting is wrapped up with foamed nickel current collector, cathode, graphite rod and stainless steel wire are then connected to molybdenum filament Collector is connected to anode；

Fused salt raw material stoving is removed into moisture removal, is placed in crucible, then crucible is put into reactor, cathode and anode are suspended in molten Above salt raw material, closed reactor is continually fed into argon gas into reactor, forms argon gas atmosphere；

Step 4：Electrolysis

(1) fused salt raw material being heated to fusion temperature and forms fused salt, cathode and anode are inserted into fused salt, constitute two electrode systems, Apply voltage in two electrodes, be electrolysed, after the completion of electrolysis, the cathode after electrolysis is taken out, it is cooling, and it is inserted into another the moon Pole applies voltage and continues to be electrolysed；Wherein, the level interval of cathode and anode be 15 ± 5mm, apply voltage be 2.0~ 2.1V, electrolysis time are 8~12h；

(2) by the cathode after cooling electrolysis, into the water, cleaned by ultrasonic vibration, the salt of removal cathode surface attachment obtains Cathode be cobalt.

2. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In, in (1) of the step 1, the discharge treatment, specially：Discharge treatment, constant-current discharge are carried out using charge and discharge instrument 3A, discharge time >=30min.

3. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in (3) of the step 2, the drying is to dry 500~600min in air at 90~100 DEG C.

4. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in (3) of the step 2, described is ground to, and obtains the Co (OH) that grain size is 0.10~0.20mm₂Powder.

5. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in (3) of the step 2, the calcination is the calcination 1~for 24 hours in air at 900~1000 DEG C.

6. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in the step 3, the graphite rod can also be SnO₂Ceramics or Ni based alloys.

7. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in the step 3, the fused salt raw material is molten chloride raw material, carbonation fused salt raw material, hydroxide fused salt original The mixing of one or more of material.

8. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as claimed in claim 7 In, when for molten chloride raw material, specially CaCl₂, LiCl, NaCl, KCl, MgCl₂, BaCl₂One or more of Fused salt mixt；

When for carbonation fused salt raw material, specially Li₂CO₃, Na₂CO₃, K₂CO₃, CaCO₃One or more of mixing it is molten Salt；

When for hydroxide fused salt raw material, specially LiOH, NaOH, the fused salt mixt of one or more of KOH.

9. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in the step 3, the argon gas is passed through by reactor air inlet, is discharged by reactor gas outlet, when discharge, will be melted The moisture that salt generates is taken away.

10. the method for cobalt element, feature exist in melten salt electriochemistry method recycling anode material of lithium battery as described in claim 1 In in the step 4, the cleaned by ultrasonic vibration, water for cleaning is the faintly acid clear water of 5≤pH≤7；Ultrasonic wave frequency Rate is 0.5kHZ~100kHZ.