阅读说明：本技术 从废旧磷酸铁锂电池回收磷酸铁锂的方法及其应用、磷酸铁锂 (Method for recycling lithium iron phosphate from waste lithium iron phosphate battery, application of method and lithium iron phosphate battery ) 是由 蒋光辉 欧阳全胜 胡敏艺 张淑琼 赵群芳 王嫦 曹贵霞 朱正宏 于 2021-08-25 设计创作，主要内容包括：本发明提供了一种从废旧磷酸铁锂电池回收磷酸铁锂的方法及其应用、磷酸铁锂,涉及废旧锂离子电池回收利用的技术领域,包括在保护性气氛下,将废旧磷酸铁锂在微波功率500～2000W、温度300～800℃下煅烧3～18h,得到重结晶的磷酸铁锂,其中,废旧磷酸铁锂包括磷酸铁锂电池中的磷酸铁锂。本发明的回收及再生磷酸铁锂的方法,其工艺简单且易于操作,解决了废旧磷酸铁锂电池中磷酸铁锂回收的技术及经济效益问题,实现了磷酸铁锂的再生,达到了废旧的磷酸铁锂电池的资源综合利用和有利于环境保护的技术效果。(The invention provides a method for recovering lithium iron phosphate from waste lithium iron phosphate batteries, application of the method and lithium iron phosphate, and relates to the technical field of waste lithium ion battery recycling. The method for recovering and regenerating the lithium iron phosphate has simple process and easy operation, solves the technical and economic benefit problems of recovering the lithium iron phosphate from the waste lithium iron phosphate batteries, realizes the regeneration of the lithium iron phosphate, and achieves the technical effects of comprehensive utilization of resources of the waste lithium iron phosphate batteries and environmental protection.)

1. A method for recovering lithium iron phosphate from waste lithium iron phosphate batteries is characterized by comprising the following steps:

calcining waste lithium iron phosphate for 3-18 h at the microwave power of 500-2000W and the temperature of 300-800 ℃ in a protective atmosphere to obtain recrystallized lithium iron phosphate;

the waste lithium iron phosphate comprises lithium iron phosphate in a lithium iron phosphate battery.

2. The method for recovering lithium iron phosphate according to claim 1, wherein the protective atmosphere comprises at least one of nitrogen and argon.

3. The method for recycling lithium iron phosphate according to claim 1, wherein the microwave power is 800-1500W.

4. The method for recovering lithium iron phosphate according to claim 1, wherein the calcination temperature is 400 to 700 ℃ and the calcination time is 5 to 16 hours.

5. The method for recovering lithium iron phosphate according to claim 1, further comprising the steps of:

A. discharging, disassembling and sorting waste lithium iron phosphate batteries serving as raw materials to obtain separated positive plates;

B. b, separating waste lithium iron phosphate on the separated positive plate obtained in the step A to obtain the waste lithium iron phosphate;

preferably, the method for separating the waste lithium iron phosphate on the positive plate in the step B includes at least one of mechanical crushing, stripping, alkaline leaching and roasting.

6. The method for recovering lithium iron phosphate according to any one of claims 1 to 5, further comprising the steps of:

and crushing and screening the recrystallized lithium iron phosphate to obtain the lithium iron phosphate.

7. Lithium iron phosphate prepared by the method for recovering lithium iron phosphate according to any one of claims 1 to 6.

8. The lithium iron phosphate according to claim 7, wherein the lithium iron phosphate is fluorine-doped lithium iron phosphate.

9. The lithium iron phosphate according to claim 8, wherein the lithium iron phosphate is lithium iron phosphate coated with lithium phosphate.

10. The use of the method for recovering lithium iron phosphate according to any one of claims 1 to 6 in the preparation of batteries.

Technical Field

The invention relates to the technical field of recycling of waste lithium ion batteries, in particular to a method for recycling lithium iron phosphate from waste lithium iron phosphate batteries, application of the method and lithium iron phosphate.

Background

The lithium iron phosphate battery is widely applied to new energy automobiles due to excellent safety performance and cycle stability. However, the economic value of the recycling treatment of the scrapped lithium iron phosphate battery is low (compared with lithium cobaltate and ternary materials), so that the recycling enthusiasm of enterprises is not high. If the scrapped lithium iron phosphate battery cannot be properly treated, serious pollution and waste can be caused to the environment and resources.

At present, most of the scrapped lithium iron phosphate batteries are used for recovering valuable metals, such as lithium, copper, aluminum and the like, some researches are carried out by adopting acid leaching and resynthesis for treatment through a traditional metallurgical method, but the results are not satisfactory, for example, the pure recovery of the valuable metals in the lithium iron phosphate batteries requires acid, which can generate a large amount of waste water and is not friendly to the environment; the traditional metallurgical method is subjected to processes such as leaching, purification, resynthesis and the like, the process also needs acid, and the flow of the treatment process is long; and other ways are used for direct regeneration, so that the problem that the surface of the lithium iron phosphate needs to be cleaned cannot be avoided, which can cause resource waste and increase the water treatment work, and meanwhile, conductive carbon and other materials in the lithium iron phosphate battery cannot be well treated and applied.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

One of the purposes of the invention is to provide a method for recovering lithium iron phosphate from waste lithium iron phosphate batteries, which has the advantages of simple process and easy operation, can recover the lithium iron phosphate from the waste lithium iron phosphate batteries, realizes the regeneration of the lithium iron phosphate, and is beneficial to environmental protection.

Another object of the present invention is to provide lithium iron phosphate.

The invention also aims to provide application of the method for recovering lithium iron phosphate from the waste lithium iron phosphate batteries in battery preparation.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

in a first aspect, the invention provides a method for recovering lithium iron phosphate from waste lithium iron phosphate batteries, which comprises the following steps:

calcining waste lithium iron phosphate for 3-18 h at the microwave power of 500-2000W and the temperature of 300-800 ℃ in a protective atmosphere to obtain recrystallized lithium iron phosphate;

the waste lithium iron phosphate comprises lithium iron phosphate in a lithium iron phosphate battery.

Further, the protective atmosphere comprises at least one of nitrogen and argon.

Furthermore, the microwave power is 800-1500W.

Furthermore, the calcining temperature is 400-700 ℃, and the calcining time is 5-16 h.

Further, the method for recovering lithium iron phosphate further comprises the following steps:

A. discharging, disassembling and sorting waste lithium iron phosphate batteries serving as raw materials to obtain separated positive plates;

B. b, separating waste lithium iron phosphate on the separated positive plate obtained in the step A to obtain the waste lithium iron phosphate;

further preferably, the method for separating the waste lithium iron phosphate on the positive electrode sheet in the step B includes at least one of mechanical crushing, stripping, alkaline leaching and roasting.

Further, the method for recovering lithium iron phosphate further comprises the following steps:

and crushing and screening the recrystallized lithium iron phosphate to obtain the lithium iron phosphate.

In a second aspect, the invention provides lithium iron phosphate prepared by any one of the above methods for recovering lithium iron phosphate.

Further, the lithium iron phosphate is fluorine-doped lithium iron phosphate.

Further, the lithium iron phosphate is lithium iron phosphate coated with lithium phosphate.

In a third aspect, the invention provides an application of a method for recovering lithium iron phosphate from waste lithium iron phosphate batteries in battery preparation.

Compared with the prior art, the invention has the following beneficial effects:

the method for recovering lithium iron phosphate from the waste lithium iron phosphate batteries provided by the invention is simple in process and environment-friendly, and realizes comprehensive utilization of waste lithium iron phosphate batteries. According to the method, the waste lithium iron phosphate is calcined under a specific microwave condition, and the recrystallization of the lithium iron phosphate is realized at a specific calcination temperature and a specific calcination time, so that the technical effect of purifying the lithium iron phosphate is achieved. Meanwhile, the binder and the conductive carbon contained in the waste lithium iron phosphate realize the carbonization effect at the specific calcination temperature and the specific calcination time, which is beneficial to improving the conductivity of the lithium iron phosphate; in addition, under the specific microwave power, the specific calcination temperature and the specific calcination time of the invention, fluorine contained in the waste lithium iron phosphate enters a lithium iron phosphate crystal lattice in a doped form, and phosphate radical contained in the waste lithium iron phosphate also forms a coating layer on the surface of the lithium iron phosphate in a lithium phosphate form. The above factors contribute to the improvement of the performance of the lithium iron phosphate product and the environmental protection.

The lithium iron phosphate provided by the invention has better conductivity.

The method for recycling lithium iron phosphate provided by the invention is applied to the preparation of batteries, is beneficial to the comprehensive utilization of waste lithium iron phosphate battery resources, and is also beneficial to the improvement of the electrical property of the batteries.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to a first aspect of the invention, a method for recovering lithium iron phosphate from waste lithium iron phosphate batteries is provided, which comprises the following steps:

calcining waste lithium iron phosphate for 3-18 h at the microwave power of 500-2000W and the temperature of 300-800 ℃ in a protective atmosphere to obtain recrystallized lithium iron phosphate;

the waste lithium iron phosphate comprises lithium iron phosphate in a lithium iron phosphate battery.

The microwave power of the invention is 500-2000W, and the typical but non-limiting power is 500W, 800W, 1000W, 1200W, 1500W; the calcination temperature of the invention is 300-800 ℃, and typical but non-limiting temperatures are, for example, 400 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃; the calcination time is 3-18 h, and typical but non-limiting time is 3h, 5h, 6h, 8h, 10h and 12 h.

According to the invention, waste lithium iron phosphate is calcined under the microwave condition, recrystallization of the lithium iron phosphate is realized at a specific calcination temperature and a specific calcination time, and the technical effect of purifying the lithium iron phosphate is achieved, so that the lithium iron phosphate is recovered, and a regenerated lithium iron phosphate product is obtained. Meanwhile, the binder and the conductive carbon contained in the waste lithium iron phosphate realize the carbonization effect at the specific calcination temperature and the specific calcination time, which is beneficial to improving the conductivity of the lithium iron phosphate; in addition, under the specific microwave power, the specific calcination temperature and the specific calcination time of the invention, fluorine contained in the waste lithium iron phosphate enters a lithium iron phosphate crystal lattice in a doped form, and phosphate contained in the waste lithium iron phosphate also forms a coating layer on the surface of the lithium iron phosphate in a lithium phosphate form. The above factors contribute to the improvement of the performance of the regenerated lithium iron phosphate product and also contribute to environmental protection.

In a preferred embodiment, the protective atmosphere of the present invention includes, but is not limited to, nitrogen and argon.

In a preferred embodiment, the microwave power of the present invention is 800 to 1500W.

In a preferred embodiment, the calcination temperature is 400-700 ℃, and the calcination time is 5-16 h.

In a preferred embodiment, the method for recovering lithium iron phosphate from waste lithium iron phosphate batteries further comprises the following steps:

A. discharging, disassembling and sorting waste lithium iron phosphate batteries serving as raw materials to obtain separated positive plates;

B. b, separating waste lithium iron phosphate on the separated positive plate obtained in the step A to obtain waste lithium iron phosphate;

and B, separating the waste lithium iron phosphate on the positive plate in the step B in a manner including but not limited to at least one of mechanical crushing, stripping, alkaline leaching and roasting.

The waste lithium iron phosphate is obtained by separating from the waste lithium iron phosphate battery, so that the resource recycling is realized, and the environment friendliness is facilitated.

In a preferred embodiment, the method for recovering lithium iron phosphate from waste lithium iron phosphate batteries further comprises the following steps:

and crushing and screening the recrystallized lithium iron phosphate to obtain the lithium iron phosphate.

After the recrystallized lithium iron phosphate is crushed and screened, the recrystallized lithium iron phosphate is convenient to pack, store and transport.

A typical method for recovering lithium iron phosphate from waste lithium iron phosphate batteries comprises the following steps:

(a) discharging, disassembling and sorting waste lithium iron phosphate batteries serving as raw materials to obtain separated positive plates;

(b) separating waste lithium iron phosphate on the separated positive plate obtained in the step (a) to obtain waste lithium iron phosphate, wherein the waste lithium iron phosphate is separated in a stripping manner;

(c) calcining the waste lithium iron phosphate obtained in the step (b) for 3-18 h at the microwave power of 500-2000W and the temperature of 300-800 ℃ in a protective atmosphere to obtain recrystallized lithium iron phosphate;

(d) and (c) crushing and screening the recrystallized lithium iron phosphate obtained in the step (c) to obtain the lithium iron phosphate.

The method comprises the following steps of firstly carrying out discharging, disassembling and sorting processes on the waste lithium iron phosphate batteries, so that the positive electrodes and the negative electrodes are separated, and separated positive plates are obtained; stripping waste lithium iron phosphate from the separated positive plate; then, calcining the stripped waste lithium iron phosphate under a microwave condition in a protective atmosphere (nitrogen or argon), so that recrystallization of the waste lithium iron phosphate is realized, and recrystallized lithium iron phosphate is obtained; and crushing and screening the recrystallized lithium iron phosphate so as to facilitate packaging, storage and transportation.

According to the invention, the recrystallization of the waste lithium iron phosphate is realized by controlling the calcination temperature and the calcination time, so that recrystallized lithium iron phosphate is obtained; meanwhile, in the calcining process, the binder and the conductive carbon in the waste lithium iron phosphate can be carbonized, so that the addition amount of the conductive carbon is reduced for the subsequent battery manufacturing process, and the conductivity of the lithium iron phosphate is improved; in addition, because the lithium iron phosphate after battery circulation contains fluorine and phosphate radicals, during the calcination process under the specific microwave condition, the fluorine enters the lithium iron phosphate crystal lattice in a doped form to form doping, and the phosphate radicals also form a coating layer on the surface of the lithium iron phosphate in a lithium phosphate form.

According to a second aspect of the present invention, there is provided lithium iron phosphate prepared by the above method for recovering lithium iron phosphate.

The lithium iron phosphate product provided by the invention is a fluorine-doped lithium iron phosphate product, and the lithium iron phosphate product provided by the invention is a lithium phosphate-coated lithium iron phosphate product.

The lithium iron phosphate product provided by the invention has better conductivity.

According to a third aspect of the invention, the application of the method for recovering lithium iron phosphate from the waste lithium iron phosphate batteries in battery preparation is provided.

The application provided by the invention is beneficial to comprehensive utilization of waste lithium iron phosphate battery resources and improvement of the electrical property of the battery.

The invention is further illustrated by the following examples. The materials in the examples are prepared according to known methods or are directly commercially available, unless otherwise specified.

Example 1

(a) Discharging, disassembling and sorting waste lithium iron phosphate batteries serving as raw materials to obtain separated positive plates;

(b) separating waste lithium iron phosphate from the separated positive plate obtained in the step (a) to obtain waste lithium iron phosphate, wherein the waste lithium iron phosphate is separated in a manner of stripping the waste lithium iron phosphate from the positive plate;

(c) calcining the waste lithium iron phosphate obtained in the step (b) for 6 hours at the microwave power of 500W and the temperature of 400 ℃ in a protective atmosphere to obtain recrystallized lithium iron phosphate;

(d) and (c) crushing and screening the recrystallized lithium iron phosphate obtained in the step (c) to obtain the lithium iron phosphate.

Example 2

The present example is different from example 1 in that in the present example, the microwave power in step (c) is 800W, and the temperature is 500 ℃ for 7h, so as to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those in example 1.

Example 3

The present example is different from example 1 in that in the present example, the microwave power in step (c) is 1000W, and the temperature is 600 ℃ for 9h, so as to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those in example 1.

Example 4

The present example is different from example 1 in that in the present example, the microwave power in step (c) is 1200W, and the temperature is 650 ℃ for 8h, so as to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those in example 1.

Example 5

The present example is different from example 1 in that in the present example, the microwave power in step (c) is 1500W, and the temperature is 700 ℃ for 8h, so as to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those in example 1.

Comparative example 1

The difference between the comparative example and the example 1 is that the microwave treatment is not performed in the step (c) of the comparative example, the waste lithium iron phosphate obtained in the step (b) is calcined at 400 ℃ for 6 hours to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those in the example 1.

Comparative example 2

The comparative example is different from example 1 in that the microwave power in step (c) of the comparative example is 2.5kW, recrystallized lithium iron phosphate is obtained, and other steps and parameters are the same as those in example 1.

Comparative example 3

The comparative example is different from example 1 in that the microwave power in step (c) of the comparative example is 200W, recrystallized lithium iron phosphate is obtained, and other steps and parameters are the same as those in example 1.

Comparative example 4

The comparative example is different from example 1 in that the calcination temperature in step (c) of the comparative example is 900 ℃ to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those of example 1.

Comparative example 5

The comparative example is different from example 1 in that the calcination temperature in step (c) of the comparative example is 200 ℃ to obtain recrystallized lithium iron phosphate, and other steps and parameters are the same as those of example 1.

Comparative example 6

The comparative example is different from example 1 in that the calcination time in step (c) of the comparative example is 2 hours, recrystallized lithium iron phosphate is obtained, and other steps and parameters are the same as those in example 1.

Comparative example 7

The comparative example is different from example 1 in that the calcination time in step (c) of the comparative example is 20 hours, recrystallized lithium iron phosphate is obtained, and other steps and parameters are the same as those in example 1.

Examples of the experiments

The button cell batteries prepared from the regenerated lithium iron phosphate materials obtained in examples 1-5 and comparative examples 1-7 are respectively used for comparative study on electrochemical performance. The button cell is manufactured according to the mass ratio of the lithium iron phosphate active substance to the conductive carbon black to the PCDF of 8: 1:1, coating the slurry on an aluminum foil, drying for 8 hours at 120 ℃, rolling and cutting to prepare a small circular pole piece for manufacturing a button cell. The button cell is assembled in a glove box under the conditions that the water and oxygen content is less than or equal to 0.01ppm and the electrolyte is 1.0M LiPF₆in EC DMC DEC 1:1:1 Vol%. Test conditions for battery performance: the charge-discharge voltage range is 2.5-4.2V (relative to Li)⁺/Li), ambient temperature 25 ℃, and charging and discharging with a 1C current density (1C ═ 150mA/g), battery performance was obtained, see table 1.

TABLE 1

Serial number	Microwave power/W	Calcination temperature/. degree.C	Calcination time/h	Battery Performance/mA/g
					Example 1	500	400	6	115.9
Example 2	800	500	7	125.6
					Example 3	1000	600	9	130.4
Example 4	1200	650	8	132.5
					Example 5	1500	700	8	129.7
Comparative example 1	—	400	6	110.3
					Comparative example 2	2500	400	6	105.8
Comparative example 3	200	400	6	106.6
					Comparative example 4	500	900	6	90.2
Comparative example 5	500	200	6	112.7
					Comparative example 6	500	400	2	111.5
Comparative example 7	500	400	20	110.7

As is clear from the description in table 1, the batteries made of lithium iron phosphate obtained in examples 1 to 5 of the present invention have more excellent battery performance than the batteries made of lithium iron phosphate obtained in comparative examples 1 to 7.

The invention has simple recovery process and environmental protection, and realizes the comprehensive utilization of lithium ion battery resources.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.