Method for instant impurity removal and synchronous preparation of graphene from waste battery negative graphite powder

Abstract

The application provides a method for instant impurity removal and synchronous preparation of graphene of waste battery negative graphite powder, and belongs to the technical field of lithium battery electrode material recycling. The method first crushes waste lithium battery negative materials, then applies a direct current voltage to the waste lithium battery negative powder or mixes the waste lithium battery negative powder with a resistance increasing agent in a certain proportion, and then applies a direct current voltage to generate current heat effect. After the reaction is completed, the solid product is taken out. In the application, one-step method is used to remove impurities of waste lithium battery negative graphite and prepare high-quality graphene. Based on the current heat effect, the Joule heat caused by the current can rapidly heat the conductor, the metal can be volatilized under the action of high temperature, and the high temperature and current can peel the graphite into high-quality and high-value-added graphene, realizing high-value conversion of the graphite, and having important scientific significance for the resource utilization technology development of the waste lithium battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium battery electrode material recycling, and particularly relates to a method for instant impurity removal and synchronous graphene preparation of waste battery negative graphite powder. BACKGROUND

[0002] The rapid iteration and update of new energy vehicles accelerate the retirement of lithium power batteries. Waste lithium batteries are rich in lithium, cobalt, nickel, iron, manganese and other metals in the positive electrode material, and are rich in graphite in the negative electrode material, which has great recycling potential. However, the price of graphite is relatively low, and the existing recycling process focuses on the metals (lithium, cobalt, nickel, manganese) in the positive electrode material of the battery, and less attention is paid to the recycling and subsequent modification and value-added of the negative electrode graphite.

[0003] At present, the recycling and resource utilization of waste lithium battery negative electrode materials mainly adopts wet treatment, uses strong acid and strong base to remove impurities in the negative electrode graphite, and further improves the graphitization degree of the material through pyrolysis and mechanical peeling, so as to achieve the purpose of high-value conversion of the negative electrode graphite.

[0004] CN201910090355 discloses a method for removing metal impurities from waste lithium battery graphite negative electrode and recycling graphite. The method is to crush the negative electrode graphite material of the waste lithium battery, and then remove the metal impurities through water washing, oxidizing acid immersion and reducing acid immersion, and further adopt microwave calcination to recycle graphite with high carbon content. Although this method can remove the metal impurities in the negative electrode material, the strong oxidizing agent used in the recycling process can cause secondary pollution, and the cost of microwave calcination is high, and the recycled graphite is difficult to balance the total cost. CN111883869A discloses a method for preparing graphene oxide using waste lithium battery graphite negative electrode as raw material. The method is to crush the negative electrode graphite material of the waste lithium battery, and then remove the impurities through acid immersion, and further adopt Hummers method to prepare graphene oxide. However, the process of recycling the graphite to regenerate graphene introduces strong acid and strong oxidizing agent, which causes serious secondary pollution, and subsequent treatment methods such as freeze-drying are required, which is difficult to operate and has high cost.

[0005] Therefore, the existing waste lithium battery negative electrode recycling and high-value conversion method has the problems of high pollution, high energy consumption, long time, high cost, and the recycling and high-value treatment process is complex, and it is difficult to realize one-step impurity removal and quality improvement. How to remove the impurities in the waste lithium battery negative electrode while improving the quality of the recycled graphite is a problem to be solved. SUMMARY

[0006] The purpose of the present application is to provide a method for instant impurity removal and synchronous graphene preparation of waste battery negative graphite powder, which aims to solve the problem of how to greenly and efficiently remove the metal in the waste lithium battery negative powder in the prior art, while realizing the high-value conversion of the negative electrode graphite.

[0007] To achieve the above object, the present application provides the following technical solutions.

[0008] A method for instant impurity removal and synchronous graphene preparation of waste battery negative graphite powder, comprising the following steps:

[0009] Step S1, firstly, the waste lithium battery negative graphite is scraped off, and the waste lithium battery negative graphite is dried and crushed to obtain waste lithium battery negative powder, which is ready for use;

[0010] Step S2, then the waste lithium battery negative powder prepared in step S1 is loaded into a quartz tube, electrodes are installed at both ends of the sample, and the sample is subjected to a direct current voltage or a direct current voltage is applied to the mixture of the waste lithium battery negative powder and the resistance increasing agent to generate current heat effect, and the solid product is taken out after the reaction is completed.

[0011] As a preferred scheme of the present application, the waste lithium battery negative powder is subjected to a direct current voltage of 150-300V in step S2.

[0012] As a preferred scheme of the present application, the reaction time of applying a direct current voltage to the waste lithium battery negative powder in step S2 is 1-100ms.

[0013] As a preferred scheme of the present application, the resistance value of the waste lithium battery negative powder is controlled by electrode extrusion.

[0014] As a preferred scheme of the present application, the electrode is connected with a direct current power supply.

[0015] As a preferred scheme of the present application, the resistance increasing agent is one of pyrolytic carbon, hydrothermal carbon or carbon-based conductive powder.

[0016] As a preferred scheme of the present application, the mass fraction of the resistance increasing agent is 1-60%.

[0017] As a preferred scheme of the present application, the solid product in step S2 is graphene.

[0018] As a preferred scheme of the present application, the solid product in step S2 is washed with a low-concentration organic acid to further improve the product purity. Specifically, on the basis of obtaining graphene, a weak acid is used to wash away the trace amount of metal on the surface of graphene, so that the purity of graphene is further improved.

[0019] As a preferred scheme of the present application, the waste lithium battery negative graphite is scraped off by tweezers or a scraper in step S1.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1. The method for removing impurities from waste lithium battery negative graphite and preparing high-quality graphene in one step, wherein a direct current voltage is applied to the sample or the waste lithium battery negative powder is mixed with a resistance enhancer in a certain proportion and then a direct current voltage is applied to generate current heat effect, the waste lithium battery negative powder is used to generate heat by itself, and the impurities can be removed within one second, which is a significant innovation because other treatment methods usually take several hours, and the time of the method is in seconds. The removal rate of impurities in the waste lithium battery negative disposal method of the present application can reach more than 50% compared with the traditional wet method, and the graphite is converted into graphene, and the number of layers of the product graphene is further reduced after the addition of the resistance enhancer (the mass fraction of the resistance enhancer is 1-60%). In addition, the impurity concentration can be further reduced by using low-concentration organic acid washing. The waste lithium battery negative disposal method of the present application has the advantages of simple operation steps, short processing flow, low cost, and the ability to recycle impurities, and the impurities in the obtained solid product are significantly reduced, strong acid and strong base are not needed for impurity removal, secondary pollution is avoided, and the solid product is graphene, which has higher benefits and application prospects.

[0022] 2. The method for removing impurities from waste lithium battery negative graphite and preparing high-quality graphene in one step, wherein the waste lithium battery negative powder is loaded into a quartz tube, electrodes are installed at both ends of the sample, the quartz tube is placed in a reactor, a direct current voltage is applied to the sample, the reaction time is 1-100 ms, the resistance of the waste lithium battery negative powder is controlled by electrode extrusion, based on the current heat effect, the Joule heat caused by the current can make the conductor heat up rapidly, the metal can be fully volatilized under high temperature, and the graphite can be peeled off into high-quality and high-value-added graphene under the action of high temperature and current, realizing high-value conversion of the graphite, and having important scientific significance for the resource utilization technology development of waste lithium batteries. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application together with the embodiments thereof, and explain the present application, and do not constitute a limitation of the present application. In the drawings:

[0024] Figure 1 It is a Raman spectrum of the waste lithium battery negative powder in the present application;

[0025] Figure 2 It is a Raman spectrum of Example 1 in the present application;

[0026] Figure 3 It is a Raman spectrum of Example 2 in the present application;

[0027] Figure 4 It is a Raman spectrum of Example 3 in the present application;

[0028] Figure 5Raman chart of Example 4 in the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] Example 1

[0031] Please refer to Figures 1-2 The present application provides the following technical solutions:

[0032] A method for instant impurity removal and synchronous preparation of graphene from waste battery negative graphite powder, comprising the following steps:

[0033] Step S1, first, the waste lithium battery negative graphite is scraped off by tweezers or a scraper, at this time, the waste lithium battery negative graphite is washed with a low-concentration organic acid, and after washing, it is crushed to obtain waste lithium battery negative powder, which is ready for use;

[0034] Step S2, then the resistance of the waste lithium battery negative powder is adjusted to a suitable range by electrode extrusion, the electrode is connected with an alternating current power supply, the output direct current voltage is adjusted to 150V, the reaction time is 30ms; the starting switch is turned on, and the solid product (FG150) is taken out after 30ms; the mass of the solid product is measured; the solid product is digested, the concentrations of Li and Fe are measured by inductively coupled plasma emission spectrometry, and the removal efficiency of impurities is obtained. In addition, the solid product is subjected to Raman test, which shows that FG150 is few-layer graphene.

[0035] In specific embodiments of the present application, in the present application, a direct current voltage is applied to the waste lithium battery negative powder, under the continuous action of the direct current voltage of 150-300V, the current heat effect generated by the circuit makes the reactants instantaneously heat up, the impurities volatilize rapidly at high temperature, and the graphite is peeled off to become graphene. Secondly, the resistance enhancer can increase the total resistance of the reactants, thereby increasing the partial pressure, enhancing the current heat effect and the electric peeling effect, further reducing the thickness of the product, and improving the quality of the graphene.

[0036] Specifically, the waste lithium battery negative powder is extruded by the electrode to adjust its resistance to a suitable range, and the electrode is connected with a direct current power supply.

[0037] Specifically, the resistance enhancer is pyrolytic carbon, hydrothermal carbon or other carbon-based conductive powder with large resistance.

[0038] Specifically, the mass fraction of the resistance enhancer is 1-60%.

[0039] Specifically, the low-concentration organic acid is used to wash the waste lithium battery negative electrode graphite in step S1, which can further reduce the impurity concentration.

[0040] Example 2

[0041] A method for instant impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder, comprising the following steps:

[0042] Step S1, first, the waste lithium battery negative electrode graphite is scraped off by tweezers or a scraper, at this time, the waste lithium battery negative electrode graphite is washed with a low-concentration organic acid, and then is crushed to obtain waste lithium battery negative electrode powder for standby use;

[0043] Step S2, then the resistance of the waste lithium battery negative electrode powder is adjusted to a suitable range by electrode extrusion, the electrode is connected with an alternating current power supply, the output direct current voltage is adjusted to 200V, the reaction time is 30ms; the starting switch is turned on, and the solid product (FG200) is taken out after 30ms; the mass of the solid product is weighed; the solid product is digested, the concentrations of Li and Fe are determined by inductively coupled plasma emission spectrometry, and the impurity removal efficiency is obtained. In addition, the solid product is subjected to Raman test, which shows that FG200 is few-layer graphene.

[0044] Example 3

[0045] A method for instant impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder, comprising the following steps:

[0046] Step S1, first, the waste lithium battery negative electrode graphite is scraped off by tweezers or a scraper, at this time, the waste lithium battery negative electrode graphite is washed with a low-concentration organic acid, and then is crushed to obtain waste lithium battery negative electrode powder for standby use;

[0047] Step S2, then the resistance of the waste lithium battery negative electrode powder is adjusted to a suitable range by electrode extrusion, the electrode is connected with an alternating current power supply, the output direct current voltage is adjusted to 250V, the reaction time is 30ms; the starting switch is turned on, and the solid product (FG250) is taken out after 30ms; the mass of the solid product is weighed; the solid product is digested, the concentrations of Li and Fe are determined by inductively coupled plasma emission spectrometry, and the impurity removal efficiency is obtained. In addition, the solid product is subjected to Raman test, which shows that FG250 is few-layer graphene.

[0048] Example 4

[0049] A method for instant impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder, comprising the following steps:

[0050] Step S1, firstly, the spent lithium battery negative electrode graphite is scraped off by tweezers or a scraper, at this time, the spent lithium battery negative electrode graphite is washed by using a low concentration organic acid, after washing, it is crushed to obtain spent lithium battery negative electrode powder, and is ready for use;

[0051] Step S2, then, the spent lithium battery negative electrode powder obtained by crushing is mixed with a resistance increasing agent, and the mass ratio is 1:1, then the resistance value of the spent lithium battery negative electrode powder is adjusted to a suitable range by electrode extrusion, the electrode is connected with an alternating current power supply, the output direct current voltage is adjusted to 250V, the reaction time is 30ms; the starting switch is turned on, and the solid product (FG250-H) is taken out after 30ms, and the mass of the solid product is weighed; the solid product is digested, the concentrations of Li and Fe are determined by inductively coupled plasma emission spectrometry, and the removal efficiency of impurities is obtained. In addition, the solid product is subjected to Raman test, and it is shown that FG250-H is thin layer graphene; the FG250-H is subjected to secondary washing by using 0.1M acetic acid solution.

[0052] After the spent lithium battery negative electrode material is crushed, it is mixed with a resistance increasing agent (the mass ratio is 1:1), and the resistance value is adjusted to a suitable range by electrode extrusion, the electrode is connected with an alternating current power supply, the output direct current voltage is adjusted to 250V, and the reaction time is 30ms; the starting switch is turned on, and the solid product (FG250-H) is taken out after 30ms, and the mass of the solid product is weighed; the solid product is digested, the concentrations of Li and Fe are determined by inductively coupled plasma emission spectrometry, and the removal efficiency of impurities is obtained. In addition, the solid product is subjected to Raman test, and it is shown that FG250-H is thin layer graphene. The FG250-H is subjected to secondary washing by using 0.1M acetic acid solution, and the removal efficiency of impurities is further improved.

[0053] Experimental result detection:

[0054] In the application, the impurities in the spent lithium battery negative electrode graphite are removed by one-step method, and high-quality graphene is prepared. Based on the current heat effect, the Joule heat caused by the current can make the conductor heat up rapidly, the metal can be volatilized under high temperature, and the high temperature and the current can strip the graphite into high-quality and high-value-added graphene, realizing the high-value conversion of the graphite, and having important scientific significance for the resource utilization technology development of the spent lithium battery;

[0055] Meanwhile, the graphene product prepared by the method for instant impurity removal and synchronous graphene preparation of the spent battery negative electrode graphite powder in the application is subjected to impurity concentration and Raman detection, wherein the detection results in Example 4 are compared with the impurity concentration content and Raman results of the spent lithium battery negative electrode powder, as shown in the following Table 1 and Table 2:

[0056] Sample Fe (mg / kg) Li (mg / kg) Spent lithium battery negative electrode powder 4200 600 Example 4 2400 Not detected Example 4 after secondary washing 1800 Not detected

[0057] Table 1: Comparison table of impurity concentration in waste lithium battery negative electrode powder and solid product

[0058]

[0059]

[0060] Table 1: Comparison table of impurity concentration in waste lithium battery negative electrode powder and solid product of Example 4

[0061] The method of the present application realizes the impurity removal of waste lithium battery negative electrode graphite and the preparation of high-quality graphene in one step. The waste lithium battery negative electrode powder itself is used to generate heat by resistance, and the impurities can be removed within one second. The waste lithium battery negative electrode disposal method of the present application has a removal rate of more than 50% for impurities compared with the traditional wet method, and converts the graphite into graphene. After adding a resistance enhancer, the number of layers of the product graphene is further reduced. In addition, using low-concentration organic acid washing can further reduce the impurity concentration. The waste lithium battery negative electrode disposal method of the present application has simple operation steps, short processing flow, low cost, and can recycle impurities. The impurities in the obtained solid product are significantly reduced, and strong acid and strong base are not needed for impurity removal, avoiding secondary pollution. The solid product is graphene, which has higher benefits and application prospects.

[0062] In the present application, a one-step method is used to realize the impurity removal of waste lithium battery negative electrode graphite and the preparation of high-quality graphene. Based on the current heat effect, the Joule heat caused by the current can rapidly heat the conductor. The metal can be volatilized under high temperature, and the high temperature and current can peel the graphite into high-quality and high-value graphene, realizing the high-value conversion of the graphite. This has important scientific significance for the resource utilization technology development of waste lithium batteries.

[0063] Finally, it should be noted that: the above is only the preferred embodiment of the present application, and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for instantaneous impurity removal and simultaneous preparation of graphene from graphite powder from the negative electrode of waste batteries, characterized in that, Includes the following steps: Step S1: First, scrape off the graphite from the negative electrode of the waste lithium battery, and then dry and crush the graphite to obtain waste lithium battery negative electrode powder for later use. Step S2: Then, the waste lithium battery negative electrode powder obtained in step S1 is loaded into a quartz tube, electrodes are added to both ends of the sample, the quartz tube is placed in the reactor, a DC voltage is applied to the sample, or the waste lithium battery negative electrode powder and the resistance enhancer are mixed in proportion and a DC voltage is applied to generate a current heating effect. After the reaction is completed, the solid product is taken out. In step S2, a DC voltage of 150-300 V is applied to the waste lithium battery negative electrode powder; In step S2, waste lithium battery negative electrode powder is loaded into a quartz tube, electrodes are added to both ends of the sample, the quartz tube is placed in the reactor, and the reaction time for applying DC voltage to the sample is 1-100ms. The resistance enhancer is one of pyrolytic carbon, hydrothermal carbon, or other carbon-based conductive powders with high resistance.

2. The method for instantaneous impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder according to claim 1, characterized in that, The resistance of the waste lithium battery negative electrode powder is controlled by electrode extrusion.

3. The method for instantaneous impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder according to claim 2, characterized in that, The electrode is connected to a DC power supply.

4. The method for instantaneous impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder according to claim 1, characterized in that, The mass fraction of the resistance enhancer is 1-60%.

5. The method for instantaneous impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder according to claim 1, characterized in that, The solid product in step S2 is graphene.

6. The method for instantaneous impurity removal and simultaneous preparation of graphene from waste battery negative electrode graphite powder according to claim 1, characterized in that, In step S2, a weak acid is used to wash away trace amounts of metal from the graphene surface, thereby further improving the purity of the graphene.

Images