阅读说明：本技术 一种利用废旧磷酸铁锂正极材料制备预锂化剂的方法 (Method for preparing pre-lithiation agent by using waste lithium iron phosphate cathode material ) 是由 李丽 张晓东 陈人杰 范二莎 林娇 吴锋 于 2021-08-02 设计创作，主要内容包括：本发明公开了一种利用废旧磷酸铁锂正极材料制备预锂化剂的方法。本发明利用废旧磷酸铁锂正极材料制备预锂化剂Li-(5)FeO-(4)的方法,包括如下步骤：将废旧磷酸铁锂正极材料与锂源混合后进行焙烧,焙烧完毕得到所述预锂化剂。本发明方法可以将废旧磷酸铁锂中的Li、Fe、P元素有效回收,其中Li、Fe以预锂化剂Li-(5)FeO-(4)的赋存形式回收,P元素以磷酸的赋存形式回收,实现了废旧磷酸铁锂全组分、高值化的回收再利用；废旧磷酸铁锂可以作为合成预锂化剂良好的铁源和锂源,且经历多次充放电后的正极材料增加了材料反应的活性,在只补充锂源的情况下,可以以较低的焙烧温度和较短的焙烧时间,实现高纯度预锂化剂Li-(5)FeO-(4)的有效合成。(The invention discloses a method for preparing a pre-lithiation agent by using a waste lithium iron phosphate cathode material. The invention utilizes the waste lithium iron phosphate anode material to prepare the pre-lithiation agent Li 5 FeO 4 The method comprises the following steps: and mixing the waste lithium iron phosphate anode material with a lithium source, and roasting to obtain the pre-lithiation agent. The method can effectively recover Li, Fe and P elements in the waste lithium iron phosphate, wherein Li and Fe are pre-lithiated by Li 5 FeO 4 The P element is recovered in the occurrence form of phosphoric acid, so that the full-component and high-value recovery and reutilization of the waste lithium iron phosphate is realized; the waste lithium iron phosphate can be used as an iron source and a lithium source for synthesizing the pre-lithiation agent, and the activity of material reaction is increased by the anode material subjected to multiple charging and discharging,under the condition of only supplementing lithium source, high-purity pre-lithiation agent Li can be realized at lower roasting temperature and shorter roasting time 5 FeO 4 The method is effective in synthesis.)

1. Prelithiating agent Li prepared from waste lithium iron phosphate cathode material₅FeO₄The method comprises the following steps: and mixing the waste lithium iron phosphate anode material with a lithium source, and roasting to obtain the pre-lithiation agent.

2. The method of claim 1, wherein: the waste lithium iron phosphate positive electrode material is obtained by separating from a waste lithium iron phosphate battery; the separation comprises the following steps:

1) discharging and disassembling the waste lithium iron phosphate battery to obtain a positive plate;

2) carrying out heat treatment on the positive plate obtained in the step 1), placing the positive plate in deionized water for ultrasonic stripping after the heat treatment is finished, and collecting mixed liquid after the ultrasonic treatment; carrying out solid-liquid separation on the mixed solution, and collecting solid-phase substances; and drying the solid-phase substance to obtain the waste lithium iron phosphate anode material.

3. The method of claim 2, wherein: the temperature of the heat treatment is 300-600 ℃, the heat preservation time is 0.2-2 h, and the heating rate is 5 ℃/min;

the heat treatment is carried out under vacuum or atmosphere conditions; the atmosphere is any one or the combination of at least two of air, oxygen, nitrogen, neon, argon and argon;

the power of ultrasonic stripping is 60-600W, and the time is 5-30 min.

4. The method according to any one of claims 1-3, wherein: the molar ratio of the waste lithium iron phosphate anode material to the lithium source is 1: 2-1: 6;

the lithium source is any one or the combination of at least two of lithium oxide, lithium hydroxide, lithium carbonate and lithium acetate.

5. The method according to any one of claims 1-4, wherein: the mixing mode is ball milling; the ball milling conditions were as follows: the ball milling speed is 300-600 rpm, the ball milling time is 1-4 h, and the ball-material ratio is 2: 1-5: 1.

6. The method according to any one of claims 1-5, wherein: the roasting temperature is 700-1200 ℃, the heat preservation time is 4-12 h, and the heating rate is 5 ℃/min;

the roasting is carried out under the vacuum or atmosphere condition; the atmosphere is any one or the combination of at least two of air, oxygen, nitrogen, neon, argon and argon.

7. The method according to any one of claims 1-6, wherein: the method further comprises the steps of: after the roasting is finished, the generated reaction tail gas is absorbed and converted by water or weak acid; the weak acid is any one of citric acid, acetic acid, ascorbic acid and malic acid.

8. Prelithiating agent Li prepared by the process of any one of claims 1 to 7₅FeO₄。

Technical Field

The invention relates to the technical field of recycling of lithium ion battery resources, in particular to a method for preparing a pre-lithiation agent Li by using a waste lithium iron phosphate anode material₅FeO₄The method of (1).

Background

Lithium ion batteries are becoming a major energy source in the energy storage, power, and consumption fields due to their advantages of high energy density, long cycle life, and small size. Particularly in the application aspect of vehicle power batteries, the lithium iron phosphate battery is highly safe and stable, and is popular with manufacturers and consumers. With the rapid development of material synthesis technology and the support of policies of governments of various countries on electric vehicles, the market of power batteries has been greatly improved and developed. However, due to the limitation of the service life of the lithium ion battery, the safe disposal of the waste power battery reaching the service life scale level becomes a problem to be solved urgently. Different from ternary and lithium cobaltate and other positive electrode material power batteries rich in valuable metal elements, the lithium iron phosphate power battery has lower economic benefit of recycling and has fewer research reports on resource recycling. Therefore, the recovery technology and safe disposal thereof are greatly restricted by economical and technical means.

At present, the recovery technology of the waste lithium iron phosphate anode material comprises recovery utilization and restoration regeneration, wherein the recovery utilization is to extract valuable lithium elements in the anode material by adopting technical means such as a wet method, a pyrogenic method or mechanochemistry, and the like, and the resource recycling mode of recycling non-complete components reduces the economic benefit of recovery while causing great waste of secondary resources; the repair regeneration is high-temperature solid-phase repair by adding lithium salt or adding new electrode material, but the performance of the regenerated electrode material is often lower than that of commercial electrode material, so the applicability of the regenerated electrode material is lower. Therefore, the high-value, short-range and full-component recovery technology is sought to be an effective breakthrough point of the recovery technology of the waste lithium iron phosphate positive electrode material. The prelithiation agent is a high-valued additive which can effectively improve the first efficiency of the battery, and is widely concerned by scholars. However, conventional prelithiation agents utilize nanoscale iron sources and lithiumThe salt is synthesized by a high-temperature solid-phase synthesis method in an inert atmosphere, so that the energy consumption is high, the production equipment has high requirements, and the method is not suitable for large-scale industrial production. The invention patent with publication number CN109205679A discloses a pre-lithiation agent Li₅FeO₄Although the preparation method can be synthesized in the air atmosphere, the roasting temperature is too high (1000 ℃), the heat preservation time is too long (as long as 72 hours), and the synthesis raw materials are expensive (nano-scale ferric oxide and lithium hydroxide are adopted), the method can obtain the pre-lithiation agent with higher purity, but the energy consumption is too high, and the economical efficiency is lower; the invention patent of publication No. CN110518297A discloses a preparation method, in which a pre-lithiation agent is obtained by a two-stage roasting heat preservation mode, although the roasting temperature is relatively reduced, the adopted method is still a chemical product-grade iron source and a lithium source, and the roasting time is still long; the invention of publication No. CN107731560A dissolves iron salt and polyvinylpyrrolidone in organic solvent, reacts in a high-pressure reaction kettle to obtain nano-scale ferric oxide, and is roasted with lithium hydroxide by a high-temperature two-stage method after ball milling, which not only complicates the process, but also brings potential threat to operators due to the introduction of organic solvent. The method is particularly important for finding a short-range and high-efficiency synthesis method by taking waste lithium iron phosphate anode materials as reactants.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for preparing a pre-lithiation agent by using a waste lithium iron phosphate positive electrode material, wherein the method takes the waste lithium iron phosphate positive electrode material and a lithium source material as raw materials, and prepares the pre-lithiation agent Li through ball-milling activation-solid phase reaction short distance₅FeO₄So as to solve the problems of low economic benefit of waste lithium iron phosphate recovery and short-range high-efficiency transformation of the pre-lithiation agent.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the invention provides a method for preparing a pre-lithiation agent Li by using a waste lithium iron phosphate anode material₅FeO₄The method comprises the following steps: and mixing the waste lithium iron phosphate anode material with a lithium source, and roasting to obtain the pre-lithiation agent.

According to the invention, waste lithium iron phosphate anode material and a lithium source are used as raw materials, after the waste lithium iron phosphate anode material is subjected to charge and discharge for multiple times, compared with commercial-grade lithium iron phosphate, the crystal structure and phase composition are evolved, in the co-roasting chemical conversion of the lithium source, the waste lithium iron phosphate anode material has higher reactivity, and along with the rise of roasting temperature, through a short-range one-stage roasting reaction, a mixed reactant is converted into a pre-lithiation agent Li₅FeO₄And a phosphorus compound, wherein the phosphorus compound is volatilized in a gaseous state by utilizing a high-temperature environment in a roasting reaction stage, so that a prelithiation agent Li with less impurities and high purity is obtained in a product₅FeO₄。

The following technical solutions are preferred but not limited to the technical solutions provided by the present invention, and the technical objects and advantages of the present invention can be better achieved and realized by the following technical solutions.

In the invention, the waste lithium iron phosphate positive electrode material is obtained by separating from a waste lithium iron phosphate battery; preferably, the separation comprises the steps of:

1) discharging and disassembling the waste lithium iron phosphate battery to obtain a positive plate;

2) carrying out heat treatment on the positive plate obtained in the step 1), placing the positive plate in deionized water for ultrasonic stripping after the treatment is finished, and collecting mixed liquid after the ultrasonic treatment; carrying out solid-liquid separation on the mixed solution, and collecting solid-phase substances; and drying the solid-phase substance to obtain the waste lithium iron phosphate anode material.

Preferably, the temperature of the heat treatment is 300 to 600 ℃, such as 300 to 500 ℃, 400 to 600 ℃, 400 ℃, 450 ℃, 500 ℃ or 600 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the heat treatment is carried out for a holding time of 0.2 to 2 hours, such as 0.5 hour, 1 hour, 1.5 hour or 2 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature rise rate of the heat treatment is 5 ℃/min.

Preferably, the heat treatment is carried out under vacuum or atmospheric conditions; the atmosphere is any one or the combination of at least two of air, oxygen, nitrogen, neon, argon and argon;

preferably, the power of the ultrasonic peeling is 60-600W, preferably 60-300W, more preferably 80-200W, such as 90W, but not limited to the recited values, and other values in the range are also applicable.

The ultrasonic peeling time is 5 to 30min, preferably 5 to 20min, such as 5min, 10min, 15min or 20min, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the solid-liquid separation is suction filtration.

Preferably, the molar ratio of the waste lithium iron phosphate cathode material to the lithium source is 1: 2-1: 6, such as 1: 3-1: 6, 1: 3-1: 4, 1: 4-1: 6, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:3, 1:4, or 1:6, but is not limited to the enumerated values, and other unrecited values within the numerical range are also applicable; the molar ratio depends on the addition of a lithium source material;

the lithium source is any one or the combination of at least two of lithium oxide, lithium hydroxide, lithium carbonate and lithium acetate; typical but non-limiting examples of combinations are: lithium oxide and hydroxide, a combination of lithium oxide and lithium carbonate, and the like.

Preferably, the mixing is performed by ball milling;

the rotation speed of the ball mill is 300-600 rpm, such as 300rpm, 350rpm, 400rpm, 450rpm, 500rpm or 600rpm, but not limited to the enumerated values, and other unrecited values in the numerical range are also applicable;

the ball milling time is 1 to 4 hours, such as 1 hour, 1.5 hours, 2 hours or 3 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

The ball-to-material ratio of the ball mill is 2:1 to 5:1, for example, 1:1, 2:1, 3:1, 4:1 or 5:1, but the ball-to-material ratio is not limited to the above-mentioned values, and other values not listed in the above-mentioned range of values are also applicable.

Preferably, the temperature of the roasting is 700-1200 ℃, such as 700-1000 ℃, 700-900 ℃, 800-1000 ℃, 700 ℃, 800 ℃, 900 ℃ or 1000 ℃, etc., but not limited to the recited values, and other values not recited in the range of the values are also applicable;

the roasting heat preservation time is 4-12 hours, such as 6-12 hours, 6-10 hours, 8-12 hours, 6 hours, 8 hours, 10 hours or 12 hours, but the roasting heat preservation time is not limited to the enumerated values, and other unrecited values in the numerical range are also applicable;

preferably, the temperature rise rate of the roasting is 5 ℃/min.

The roasting is carried out under the vacuum or atmosphere condition; the atmosphere is any one or the combination of at least two of air, oxygen, nitrogen, neon, argon and argon.

Preferably, the method further comprises the steps of: absorbing and converting the generated reaction tail gas through water or weak acid after roasting is finished, wherein the water is deionized water; the weak acid is any one of citric acid, acetic acid, ascorbic acid and malic acid.

The invention has the following beneficial effects:

(1) the invention provides a method for high-valued short-range conversion of a pre-lithiation agent from waste lithium iron phosphate, which can effectively recover Li, Fe and P elements in the waste lithium iron phosphate by a two-step reaction method, wherein the Li and the Fe are pre-lithiated by the pre-lithiation agent Li₅FeO₄The P element is recovered in the occurrence form of phosphoric acid, so that the full-component and high-value recovery and reutilization of the waste lithium iron phosphate is realized. In addition, the method does not need inert atmosphere protection, is simple to operate, and realizes comprehensive cyclic utilization of waste resources to the maximum extent.

(2) The waste lithium iron phosphate in the preparation method can be used as an iron source and a lithium source for synthesizing the pre-lithiation agent, the activity of material reaction is increased by the anode material subjected to multiple charging and discharging, and the high-purity pre-lithiation agent Li can be realized at a lower roasting temperature and a shorter roasting time under the condition of only supplementing the lithium source₅FeO₄The method is effective in synthesis.

(3) The preparation method disclosed by the invention is simple in flow, reaction conditions are easy to control, the lithium iron phosphate anode material with low recovery value can be converted into the pre-lithiation agent with high economic value in a short-range manner, and the method has important significance for full-component recovery, high-value utilization and large-scale recovery of waste power batteries.

Drawings

FIG. 1 shows that the lithium pre-lithiation agent Li is regenerated by the waste lithium iron phosphate battery anode material in a short-range manner in the embodiment of the invention₅FeO₄The process flow diagram of (1).

Fig. 2 is an XRD diffraction pattern of the waste lithium iron phosphate positive electrode material (400 ℃ for 1h) after heat treatment in example 1.

FIG. 3 is (a) an XRD diffraction pattern and (b) an SEM morphology pattern of the pre-lithiating agent prepared in example 1.

Detailed Description

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Example 1 preparation of prelithiation agent by using anode material of waste lithium iron phosphate power battery

According to the process flow chart shown in fig. 1, a pre-lithiation agent is prepared by using a waste lithium iron phosphate power battery anode material, a lithium source is lithium oxide, and the method specifically comprises the following steps:

s1, discharging and disassembling the waste lithium iron phosphate power battery to obtain a positive plate;

s2, preserving the temperature of the positive plate in the step S1 in a muffle furnace at 400 ℃ for 1h for heat treatment (the temperature rising rate is 5 ℃/min); taking deionized water as an ultrasonic stripping medium, carrying out ultrasonic stripping on the heat-treated positive plate in a numerical control ultrasonic cleaner at 90W for 10min, carrying out suction filtration, and drying in a vacuum drying oven at 80 ℃ for 12h to obtain a positive electrode material;

s3, ball-milling the positive electrode material obtained in the step S2 and lithium oxide for 1h at a ball-material ratio of 4:1 and a rotation speed of 400rpm in a molar ratio of 1:3, and uniformly mixing;

s4, preserving the temperature of the ball-milled material obtained in the step S3 in a muffle furnace at 900 ℃ for 10 hours for roasting (the temperature rise rate is 5 ℃/min), and cooling to room temperature to obtain the pre-lithiating agent Li₅FeO₄And the generated reaction tail gas is converted into phosphoric acid through simple water absorption.

In this example, the main phase of the heat-treated product of step S2 was Li by X-ray diffraction (XRD) analysis_0.05FePO₄The XRD pattern is shown in figure 2; the main phase of the calcination product of the step S4 is the pre-lithiation agent Li by X-ray diffraction (XRD) analysis₅FeO₄The crystallinity of the product is better, and an XRD pattern and an SEM appearance pattern are shown in figure 3.

Embodiment 2, preparation of pre-lithiation agent by using waste lithium iron phosphate power battery anode material

According to the process flow chart shown in fig. 1, a pre-lithiation agent is prepared by using a waste lithium iron phosphate power battery anode material, a lithium source is lithium oxide, and the method specifically comprises the following steps:

s1, discharging and disassembling the waste lithium iron phosphate power battery to obtain a positive plate;

s2, preserving the temperature of the positive plate in the step S1 in a muffle furnace at 600 ℃ for 1h for heat treatment (the temperature rising rate is 5 ℃/min); taking deionized water as an ultrasonic stripping medium, carrying out ultrasonic stripping on the heat-treated positive plate in a numerical control ultrasonic cleaner at 90W for 10min, carrying out suction filtration, and drying in a vacuum drying oven at 80 ℃ for 12h to obtain a positive electrode material;

s3, ball-milling the positive electrode material obtained in the step S2 and lithium oxide for 2 hours at a ball-to-material ratio of 4:1 and a rotation speed of 400rpm according to a molar ratio of 1:4, and uniformly mixing;

s4, preserving the temperature of the ball-milled material obtained in the step S3 in a muffle furnace at 900 ℃ for 12h for roasting (the temperature rise rate is 5 ℃/min), and cooling to room temperature to obtain the pre-lithiating agent Li₅FeO₄And the generated reaction tail gas is converted into phosphoric acid through simple water absorption.

In this example, the main phase of the calcination product of step S4 was pre-lithiating agent Li by X-ray diffraction (XRD) analysis₅FeO₄And the crystallinity is better.

Example 3 preparation of prelithiation agent by using anode material of waste lithium iron phosphate power battery

According to the process flow chart shown in fig. 1, a pre-lithiation agent is prepared by using a waste lithium iron phosphate power battery anode material, a lithium source is lithium hydroxide, and the method specifically comprises the following steps:

s1, discharging and disassembling the waste lithium iron phosphate power battery to obtain a positive plate;

s2, preserving the temperature of the positive plate in the step S1 in a muffle furnace at 400 ℃ for 1h for heat treatment (the temperature rising rate is 5 ℃/min); taking deionized water as an ultrasonic stripping medium, carrying out ultrasonic stripping on the heat-treated positive plate in a numerical control ultrasonic cleaner at 90W for 5min, carrying out suction filtration, and drying in a vacuum drying oven at 80 ℃ for 12h to obtain a positive electrode material;

s3, ball-milling the electrode material obtained in the step S2 and lithium hydroxide for 1.5h at a ball-to-material ratio of 4:1 and a rotation speed of 400rpm according to a molar ratio of 1:6, and uniformly mixing;

s4, keeping the temperature of the ball-milled material obtained in the step S3 in a muffle furnace at 800 ℃ for 8 hours for roasting (the temperature rise rate is 5 ℃/min), and cooling to room temperature to obtain the pre-lithiating agent Li₅FeO₄And the generated reaction tail gas is converted into phosphoric acid through simple water absorption.

In this example, the main phase of the calcination product of step S4 was pre-lithiating agent Li by X-ray diffraction (XRD) analysis₅FeO₄And the crystallinity is better.

Example 4 preparation of a prelithiation agent by using a waste lithium iron phosphate power battery positive electrode material

According to the process flow chart shown in fig. 1, a pre-lithiation agent is prepared by using a waste lithium iron phosphate power battery positive electrode material, a lithium source is lithium carbonate, and the method specifically comprises the following steps:

s1, discharging and disassembling the waste lithium iron phosphate power battery to obtain a positive plate;

s2, performing heat treatment on the positive plate in the step S1 in a muffle furnace at 600 ℃ for 1h (the temperature rise rate is 5 ℃/min); taking deionized water as an ultrasonic stripping medium, carrying out ultrasonic stripping on the heat-treated positive plate in a numerical control ultrasonic cleaner at 90W for 15min, carrying out suction filtration, and drying in a vacuum drying oven at 80 ℃ for 12h to obtain a positive electrode material;

s3, ball-milling the electrode material obtained in the step S2 and lithium carbonate for 1h under the conditions that the ball-material ratio is 4:1 and the rotating speed is 400rpm according to the molar ratio of 1:3, and uniformly mixing;

s4, preserving the temperature of the ball-milled material obtained in the step S3 in a muffle furnace at 1000 ℃ for 6 hours for roasting (the temperature rise rate is 5 ℃/min), and cooling to room temperature to obtain the pre-lithiating agent Li₅FeO₄And the generated reaction tail gas is converted into phosphoric acid through simple water absorption.

In this example, the main phase of the calcination product in step S4 was pre-lithiating agent Li by X-ray diffraction (XRD) analysis₅FeO₄And the crystallinity is better.

Example 5 preparation of a prelithiation agent by using a waste lithium iron phosphate power battery cathode material

According to the process flow chart shown in fig. 1, a pre-lithiation agent is prepared by using a waste lithium iron phosphate power battery anode material, a lithium source is lithium acetate, and the method specifically comprises the following steps:

s1, discharging and disassembling the waste lithium iron phosphate power battery to obtain a positive plate;

s2, preserving the temperature of the positive plate in the step S1 in a muffle furnace at 400 ℃ for 1h for heat treatment (the temperature rising rate is 5 ℃/min); taking deionized water as an ultrasonic stripping medium, carrying out ultrasonic stripping on the heat-treated positive plate in a numerical control ultrasonic cleaner at 90W for 10min, carrying out suction filtration, and drying in a vacuum drying oven at 80 ℃ for 12h to obtain a positive electrode material;

s3, ball-milling the electrode material obtained in the step S2 and lithium acetate for 1h and uniformly mixing the electrode material and the lithium acetate according to the molar ratio of 1:6 under the conditions that the ball-to-material ratio is 4:1 and the rotating speed is 400 rpm;

s4, preserving the temperature of the ball-milled material obtained in the step S3 in a muffle furnace at 900 ℃ for 10 hours for roasting (the temperature rise rate is 5 ℃/min), and cooling to room temperature to obtain the pre-lithiating agent Li₅FeO₄And the generated reaction tail gas is converted into phosphoric acid through simple water absorption.

In this example, the main phase of the calcination product of step S4 was pre-lithiating agent Li by X-ray diffraction (XRD) analysis₅FeO₄And crystallization thereofThe degree is better.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It will be apparent to those skilled in the art that any modification, equivalent substitution of materials for the invention, addition of additional materials, selection of specific means, etc., which are apparent to those skilled in the art are intended to be within the scope and disclosure of the invention.