CN106384855A - Recovery method of waste lithium iron phosphate positive electrode material - Google Patents

Abstract

A method for recycling waste lithium iron phosphate positive electrode materials, comprising: calcining the waste lithium iron phosphate positive electrode sheet at high temperature, so that the lithium iron phosphate active material and the aluminum foil of the current collector fall off, and then sieving to obtain the lithium iron phosphate active material; For the lithium iron active material, the lithium iron phosphate active material is mixed with graphite, ball milled with ethanol as a medium, and then dried to obtain a lithium iron phosphate precursor mixture. The iron element of lithium iron phosphate in the waste lithium iron phosphate positive electrode material is easily oxidized into iron oxide during battery use and high temperature sintering, which reduces the performance of the lithium iron phosphate positive electrode material. The oxidized part in the lithium iron phosphate positive electrode material is reduced, and the purpose of recycling the waste lithium iron phosphate positive electrode material is achieved.

Description

A kind of recycling method of waste lithium iron phosphate cathode material

technical field

The invention relates to the technical field of power battery recycling, in particular to a method for recycling waste lithium iron phosphate cathode materials.

Background technique

Lithium-ion batteries have the advantages of long cycle life, high specific energy, stable discharge voltage, small size, and no memory effect. Lithium-ion batteries can be used in portable devices, satellites, reserve power, electric vehicles and other fields, and have broad development prospects. The implementation of my country's 863 major special projects for new energy vehicles can predict that the marketization and industrialization of my country's electric vehicles will come soon. In recent years, based on the development of renewable energy, there will be a huge demand for energy storage equipment.

Lithium iron phosphate has the advantages of safety, environmental protection, good stability, high specific capacity, and low price, and is considered to be an important candidate cathode material in power batteries and energy storage batteries. Therefore, the market potential of lithium iron phosphate batteries is very huge. It is foreseeable that the production and usage of lithium iron phosphate materials will increase significantly. Therefore, the recycling of waste lithium iron phosphate batteries is also of great significance, which is not only conducive to environmental protection, but also conducive to the recycling of resources.

Contents of the invention

The invention provides a method for recycling waste lithium iron phosphate cathode materials. The method is simple and easy to make waste lithium iron phosphate into a reusable lithium iron phosphate precursor mixture. The method is realized by the following scheme:

A method for recovering waste lithium iron phosphate cathode material, comprising the steps of,

Step 1, calcining the waste lithium iron phosphate positive electrode at high temperature, so that the lithium iron phosphate active material and the aluminum foil of the current collector fall off, and then sieving to obtain the lithium iron phosphate active material;

Step 2: mix the obtained lithium iron phosphate active material with graphite, and use ethanol as a medium to perform ball milling, and then dry to obtain a lithium iron phosphate precursor mixture.

Preferably, in step 1, the calcining temperature of lithium iron phosphate is 600-800°C.

Preferably, in step 2, the molar ratio of lithium iron phosphate active material to graphite is 1:0.3-0.5.

In the present invention, the iron element of lithium iron phosphate in the waste lithium iron phosphate positive electrode material is easily oxidized into iron oxide during battery use and high-temperature sintering, which reduces the performance of the lithium iron phosphate positive electrode material. The solution of the present invention is simple and easy The oxidized part in the waste lithium iron phosphate cathode material can be effectively reduced, and the purpose of recycling the waste lithium iron phosphate cathode material is achieved.

detailed description

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example 1

The recovered lithium iron phosphate positive electrode sheet was calcined at 800° C., so that the lithium iron phosphate active material and the aluminum foil of the current collector fell off, and then sieved to obtain the lithium iron phosphate active material.

Mix and disperse the lithium iron phosphate active material and graphite in ethanol at a ratio of 1:0.5, perform ball milling, and dry after ball milling for 4 hours to obtain a lithium iron phosphate precursor mixture.

Example 2

The recovered lithium iron phosphate positive electrode sheet was calcined at 900° C., so that the lithium iron phosphate active material and the aluminum foil of the current collector fell off, and then sieved to obtain the lithium iron phosphate active material.

Mix and disperse the lithium iron phosphate active material and graphite in ethanol at a ratio of 1:0.4, perform ball milling, and dry after ball milling for 4 hours to obtain a lithium iron phosphate precursor mixture.

Example 3

The recovered lithium iron phosphate positive electrode sheet was calcined at 600° C., so that the lithium iron phosphate active material and the aluminum foil of the current collector fell off, and then sieved to obtain the lithium iron phosphate active material.

Mix and disperse the lithium iron phosphate active material and graphite in ethanol at a ratio of 1:0.3, perform ball milling, and dry the mixture after ball milling for 4 hours to obtain a lithium iron phosphate precursor mixture.

Example 4

Calculating the mass changes of the lithium iron phosphate powders in Examples 1, 2, and 3 before and after ball milling, they were reduced by 4.2%, 3.9%, and 4.1%, respectively.

The lithium iron phosphate precursor obtained in Examples 1, 2, and 3 is made into a recycled lithium iron phosphate battery, and its battery capacity is 99.7% of the capacity of a non-recyclable lithium iron phosphate battery, and the electric capacity of lithium iron phosphate is higher than that of the direct two The capacity of the secondary battery made of waste lithium iron phosphate cathode material is 30% higher.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (5)

1. a kind of recovery method of waste lithium iron phosphate positive electrode is it is characterised in that comprise the steps,

Step one, by waste lithium iron phosphate positive plate high-temperature calcination so that lithium-iron phosphate active material is come off with current collector aluminum foil, Then screening obtains lithium-iron phosphate active material；

Step 2, lithium-iron phosphate active material is mixed by the lithium-iron phosphate active material obtaining with graphite, and with ethanol for being situated between Matter, carries out ball milling, then dries, and obtains ferric lithium phosphate precursor mixture.

2. a kind of recovery method of waste lithium iron phosphate positive electrode according to claim 1 is it is characterised in that step one In, LiFePO4 calcining heat is 600～900 DEG C.

3. a kind of recovery method of waste lithium iron phosphate positive electrode according to claim 1 and 2 is it is characterised in that walk In rapid two, lithium-iron phosphate active material is 1 with the mol ratio of graphite:0.3～0.5.

4. a kind of recovery method of waste lithium iron phosphate positive electrode according to claim 3 is it is characterised in that step 2 In, lithium-iron phosphate active material is 1 with the mol ratio of graphite:0.3、1:0.4、1:0.5.

5. a kind of recovery method of waste lithium iron phosphate positive electrode according to claim 3 is it is characterised in that step 2 In, lithium-iron phosphate active material is 4h with the time of graphite ball milling.