Resource utilization method of waste lithium iron phosphate positive electrode material

Abstract

The invention belongs to the field of resourceful treatment of battery positive electrode materials, particularly relates to a resourceful utilization method of a waste lithium iron phosphate positive electrode material, and particularly relates to a method for preparing a regenerated LiZnPO4 material by using the waste lithium iron phosphate positive electrode material, which comprises the following steps of: mixing zinc powder and the waste lithium iron phosphate positive electrode material, preserving heat and roasting at the temperature of 450-650 DEG C; then separating to obtain a regenerated LiZnPO4 material; the Zn / Fe element molar ratio of the zinc powder to the waste lithium iron phosphate positive electrode material is more than 0.95. The invention also comprises the regenerated LiZnPO4 material obtained by the method and an application of the regenerated LiZnPO4 material in a photosensitive material. According to the method, the waste lithium iron phosphate material and the zinc powder are creatively roasted at the Zn / Fe element molar ratio and the temperature, and the LiZnPO4 material can be prepared in a one-pot high-selectivity mode.

Description

Technical Field

[0001] The invention belongs to the field of battery waste recycling, and specifically relates to the field of waste lithium battery material recycling. Background Art

[0002] Lithium-ion batteries are widely used in mobile electronic devices and electric vehicles due to their high energy density, excellent cycle performance and low memory effect. Following the ternary cathode materials, lithium iron phosphate cathode materials have developed rapidly and become the key competitive advantage of lithium-ion battery cathode materials. However, their performance decreases after 1,000 cycles, which means that the life of lithium-ion batteries has been reached in about 5 years, resulting in a large number of waste lithium-ion batteries. The large amount of valuable elements contained in them, if not recycled, will cause a large amount of resource waste and environmental pollution.

[0003] At present, for waste lithium iron phosphate batteries, the main idea is to use wet methods, fire methods and other methods to recover valuable elements or repair and regenerate them to obtain positive electrode active materials.

[0004] For example, the Chinese patent document with publication number CN110690429A discloses a method for processing waste lithium iron phosphate, which specifically records a scheme of treating waste lithium iron phosphate with phosphoric acid, sulfide, and iron powder, sintering with lithium, and carbon coating to obtain a regenerated positive electrode material. For another example, the Chinese patent document with publication number CN115224381A discloses a method for processing and regenerating waste battery positive electrode sheets, which specifically records a scheme of adding a lithium source and a carbon source to a mixture of ferric oxide and lithium ferrous phosphate, then calcining under an inert gas, and finally regenerating it into a lithium iron phosphate positive electrode material by carbon thermal reduction.

[0005] In summary, the main current recycling idea is to repair waste lithium iron phosphate to obtain regenerated positive electrode materials, and there is no technology to regenerate waste lithium iron phosphate materials to obtain LiZnPO4. Summary of the invention

[0006] In view of the gap in the existing technology, the present invention innovatively provides a technical gap in preparing LiZnPO4 from a lithium iron phosphate positive electrode material, aiming to provide a method for preparing a recycled LiZnPO4 material using waste lithium iron phosphate positive electrode material.

[0007] The second object of the present invention is to provide a regenerated LiZnPO4 material obtained by the method.

[0008] The third purpose of the present invention is to utilize the recycled LiZnPO4 material to prepare the application of photosensitive material.

[0009] The prior art does not have a method for one-step transformation and regeneration of waste lithium iron phosphate cathode materials into LiZnPO4 materials. Aiming at this gap in the industry, the present invention provides the following solution:

[0010] A method for preparing a regenerated LiZnPO4 material using waste lithium iron phosphate positive electrode material, comprising mixing zinc powder and waste lithium iron phosphate positive electrode material, calcining at a temperature of 450 to 650° C., and then separating to obtain the regenerated LiZnPO4 material;

[0011] The Zn / Fe element molar ratio of the zinc powder and waste lithium iron phosphate positive electrode material is above 0.95.

[0012] The present invention is the first in the industry to provide a way of recycling waste lithium iron phosphate materials into LiZnPO4 materials. The present invention innovatively calcines the waste lithium iron phosphate materials and zinc powder at the Zn / Fe element molar ratio and temperature, and can prepare LiZnPO4 materials in one pot with high selectivity. The method of the present invention has a wide tolerance for the quality of the treatment object, a large treatment volume, a high conversion rate, and the obtained product has multiple application advantages. The present invention realizes the efficient recovery of valuable elements in waste lithium-ion battery positive electrode materials without acid and alkali additives and without generating wastewater, and realizes cross-utilization in other fields.

[0013] In the present invention, the waste lithium iron phosphate positive electrode material is the positive electrode material obtained by stripping the positive electrode sheet of the waste lithium iron phosphate battery.

[0014] The waste lithium iron phosphate positive electrode material of the present invention can be obtained by disassembling and stripping based on conventional means and methods.

[0015] In the present invention, the waste lithium iron phosphate positive electrode material is allowed to contain components such as conductive agents and binders that are allowed to be added to positive electrode materials.

[0016] In the present invention, the content of lithium iron phosphate in the waste lithium iron phosphate positive electrode material can be above 50wt.%, and considering the process recovery value, the content can be further above 80wt.%, and further can be 80-95wt.%.

[0017] In the present invention, waste lithium iron phosphate and zinc powder are mixed, and through the combination of the Zn / Fe element molar ratio and temperature, LiZnPO4 material can be synthesized in one pot with high efficiency, high conversion rate and high selectivity.

[0018] In the present invention, considering the preparation effect and cost, the Zn / Fe element molar ratio of the zinc powder and waste lithium iron phosphate positive electrode material is 0.95 to 5 times, preferably 1 to 1.2 times; further 1.05 to 1.2: 1. The present invention shows that under this preferred condition, the processing effect of the new idea can be further improved, and the yield and physical and chemical characteristics of the LiZnPO4 material can be significantly improved.

[0019] In the present invention, considering the preparation effect and cost, the calcination temperature is 500-620° C., and further 590-610° C. The present invention shows that under the above conditions, it is helpful to further optimize the conversion rate, and in addition, it is also beneficial to optimize the physical and chemical characteristics of the prepared LiZnPO4 material.

[0020] In the present invention, the calcination time is more than 0.5 h, and considering the processing efficiency, it can be further 1 to 5 h, further 1 to 3 h, and further 1.5 h to 2.5 h.

[0021] In the present invention, the calcined product can be separated by conventional means. For example, in an optional scheme of the present invention, the calcined product is subjected to magnetic separation to obtain iron element and regenerated LiZnPO4 material.

[0022] The invention also provides a regenerated LiZnPO4 material prepared by the method.

[0023] The method described in the present invention can endow the prepared regenerated LiZnPO4 material with special physical and chemical characteristics, and the prepared regenerated LiZnPO4 material can show good performance.

[0024] The present invention also provides an application of a regenerated LiZnPO4 material, wherein the regenerated LiZnPO4 material is doped with rare earth ions to obtain a rare earth ion-doped photosensitive material.

[0025] The application of the regenerated LiZnPO4 material obtained by the method described in the present invention is to dope the regenerated LiZnPO4 material with rare earth ions to obtain a rare earth ion-doped photosensitive material.

[0026] In the present invention, the rare earth ions may include, for example, Yb 3+ ,La 2+ 、Nd 2+ 、Pm 2+ , Er 2+ 、Lu 2+ At least one of .

[0027] In the present invention, the regenerated LiZnPO4 material, the rare earth ion source and the carbon source can be gelled to obtain a gel, which is then calcined to obtain the obtained product. The carbon source can be polyethylene glycol, for example. The calcination temperature can be, for example, 500 to 800° C. The calcination time can be, for example, 1 to 5 hours.

[0028] In the present invention, the content of the rare earth ions in the photosensitive material is 0.5-10%.

[0029] The invention also provides the photosensitive material used.

[0030] Beneficial Effects

[0031] The present invention provides a new recycling method for waste lithium iron phosphate batteries, which innovatively calcines the waste lithium iron phosphate material and zinc powder at the Zn / Fe element molar ratio and temperature, so that LiZnPO4 material can be prepared in one pot with high selectivity and efficiency.

[0032] The regeneration method of the present invention can give the regenerated LiZnPO4 material excellent physical and chemical characteristics. The regenerated LiZnPO4 material obtained by the method can show excellent performance, for example, excellent photosensitive materials can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the XRD diagram of the waste lithium iron phosphate positive electrode powder of Example 1;

[0034] Figure 2 This is the XRD pattern of the calcined product of Example 1. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0036] In the present invention, waste lithium iron phosphate positive electrode material can be obtained by stripping from waste lithium iron phosphate battery positive electrode sheets based on conventional means; there is no special requirement for the content of lithium iron phosphate material therein, and considering the economy of the process, its content is preferably above 50wt.%, and in the following cases, unless otherwise stated, the content of lithium iron phosphate active material is 85-90wt.%.

[0037] Example 1

[0038] Step 1:

[0039] The zinc powder and the waste lithium iron phosphate positive electrode material were fully ground and mixed in a Zn / Fe molar ratio of 1.1:1, and then placed in a corundum sintering boat, and then calcined in a tubular furnace in an argon atmosphere, with a heating rate of 5°C / min and a temperature of 600°C (marked as T), and kept at this temperature for 2h (marked as t).

[0040] Step 2:

[0041] The calcined mixture was separated by magnetic separation to obtain Fe and LiZnPO4. The yield of LiZnPO4 was 99.8%. The XRD spectrum of the waste lithium iron phosphate positive electrode powder is shown in the attached Figure 1 The XRD pattern obtained after calcination is shown in the attached Figure 2In the present invention, based on the reaction of Zn+LiFePO4=LiZnPO4+Fe, under the above conditions, Fe element and LiZnPO4 with a purity close to 100% can be completely decomposed to obtain.

[0042] Example 2

[0043] Compared with Example 1, the only difference is that the amount of zinc powder is changed to make the molar ratio of Zn / Fe. The experimental groups are:

[0044] Group A: Zn / Fe molar ratio 1:1;

[0045] Group B: Zn / Fe molar ratio 0.95:1;

[0046] Other operations and parameters are the same as in Example 1;

[0047] The results are:

[0048] Group A: The yield of LiZnPO4 was 93%.

[0049] Group B: The yield of LiZnPO4 was 81%.

[0050] Example 3

[0051] Compared with Example 1, the only difference is that the roasting temperature T and the holding time t are changed. The experimental groups are:

[0052] Group A: calcination temperature T is 450°C;

[0053] Group B: calcination temperature T is 550°C;

[0054] Other operations and parameters are the same as in Example 1;

[0055] The results are:

[0056] Group A: The yield of LiZnPO4 was 80%;

[0057] Group B: The yield of LiZnPO4 was 87%.

[0058] Example 4

[0059] LiZnPO4 and Yb(NO3)3 obtained in Example 1 were mixed and dispersed in polyethylene glycol, stirred and heated at 80°C to form a gel, and dried to obtain a precursor material, which was calcined at 600°C for 3h to obtain Yb 3+ Doped LiZnPO4.

[0060] Comparative Example 1

[0061] Compared with Example 1, the only difference is that zinc powder is not added. Other operations and parameters are the same as Example 1. After the heat preservation treatment, no LiZnPO4 is detected by XRD.

[0062] Comparative Example 2

[0063] Compared with Example 1, the only difference is that the zinc powder is replaced with carbon, the C / Fe molar ratio is maintained at 1.1:1, and the other operations and parameters are the same as Example 1. The product after heat preservation in step (1) is tested by XRD, and the waste phase has no obvious change, and no LiZnPO4 phase product is detected.

[0064] Comparative Example 3

[0065] Compared with Example 1, the only difference is that the temperature T is 700° C., and the other operations and parameters are the same as Example 1. The product after heat preservation in step (1) was tested by XRD, and no LiZnPO4 phase product was detected.

[0066] Comparative Example 4

[0067] Compared with Example 1, the only difference is that the temperature is 400° C., and the other operations and parameters are the same as Example 1. The product after heat preservation in step (1) was tested by XRD, and no LiZnPO4 phase product was detected.

Claims

1. A method for preparing regenerated LiZnPO4 material using waste lithium iron phosphate positive electrode material, characterized in that: Zinc powder and waste lithium iron phosphate positive electrode materials are mixed and then calcined at a temperature of 450 to 650° C., and then separated to obtain regenerated LiZnPO4 materials; The Zn / Fe element molar ratio of the zinc powder and waste lithium iron phosphate positive electrode material is above 0.

95.

2. The method according to claim 1, characterized in that The waste lithium iron phosphate positive electrode material is the positive electrode material after the positive electrode sheet of the waste lithium iron phosphate battery is peeled off; Preferably, in the waste lithium iron phosphate positive electrode material, the content of lithium iron phosphate is preferably above 50 wt.%, more preferably above 80 wt.%, and further preferably can be 80-95 wt.%.

3. The method according to claim 1, characterized in that The molar ratio of Zn / Fe of the zinc powder and waste lithium iron phosphate positive electrode material is 0.95 to 5 times, preferably 1 to 1.2 times.

4. The method according to claim 1, characterized in that The calcination temperature is 500-620°C.

5. The method according to claim 1, characterized in that The calcination time is 0.5 h or longer, preferably 1 to 5 h, and more preferably 1 to 3 h.

6. The method according to claim 1, characterized in that The calcined product is subjected to magnetic separation to obtain iron element and regenerated LiZnPO4 material.

7. A regenerated LiZnPO4 material obtained by the method according to any one of claims 1 to 6.

8. An application of a regenerated LiZnPO4 material obtained by the method according to any one of claims 1 to 6, characterized in that: The regenerated LiZnPO4 material is doped with rare earth ions to obtain a rare earth ion-doped photosensitive material.

9. The use of the regenerated LiZnPO4 material obtained by the method according to claim 8, characterized in that: Doping the regenerated LiZnPO4 material with rare earth ions to obtain a rare earth ion-doped photosensitive material; Preferably, the rare earth ions include Yb 3+ ,La 2+ 、Nd 2+ 、Pm 2+ , Er 2+ 、Lu 2+ At least one of; Preferably, the content of the rare earth ions in the photosensitive material is 0.5-10%.

10. A photosensitive material according to the use of claim 8 or 9.

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