A pre-lithiated phosphorene material, a preparation method thereof, a negative electrode, and a lithium-ion battery

Abstract

The present invention belongs to the technical field of lithium-ion batteries, and provides a prelithiated phosphorene material, a preparation method thereof, a negative electrode and a lithium-ion battery. The preparation method of the prelithiated phosphorene material includes: adding a lithium salt and phosphorene into a first solvent, performing ultrasonic treatment, then centrifuging, filtering the obtained supernatant, drying the obtained filter cake, to obtain the prelithiated phosphorene material. Based on the prepared prelithiated phosphorene material, a prelithiated negative electrode and a lithium-ion battery can be prepared. By directly prelithiating phosphorene, the present invention avoids the need for special equipment, reduces the process complexity of negative electrode prelithiation, and at the same time, improves the structural stability of the negative electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a prelithiated phosphorene material, a preparation method thereof, a negative electrode, and a lithium-ion battery. Background Art

[0002] Lithium-ion batteries have become one of the widely used electrochemical energy storage systems due to their high energy density, high working voltage, and long cycle life.

[0003] However, the traditional graphite negative electrode used in lithium-ion batteries has a relatively low theoretical specific capacity (372 mA h g -1 ), making it difficult to meet the increasingly demanding market requirements. In recent years, researchers have proposed various new negative electrodes, such as phosphorene negative electrodes. As an emerging two-dimensional material, phosphorene is considered a strong candidate for the next-generation lithium-ion battery negative electrode material due to its high theoretical specific capacity (2596 mA h g -1 ) and high electrical conductivity. However, when used as a negative electrode material, phosphorene has poor structural stability, which leads to a decline in cycle performance. At the same time, an excessive solid electrolyte interface phase will be formed, thereby excessively consuming lithium from the positive electrode.

[0004] Therefore, the prelithiation technology of lithium-ion battery negative electrodes has become an important means to improve the performance of lithium-ion batteries. The prelithiation technology is to add a small amount of lithium source to the negative electrode before the formal charge-discharge cycle of the lithium-ion battery to make up for the lithium consumption during the charge-discharge reaction process of the lithium-ion battery, thereby improving the charge-discharge efficiency, energy density, and cycle stability of the lithium-ion battery. The existing negative electrode prelithiation technologies mainly include the following: supplementing elemental lithium on the negative electrode surface, electrochemical prelithiation, and continuous electrodeposition prelithiation technology, etc. The prelithiation technology of supplementing elemental lithium on the negative electrode surface is to directly contact metallic lithium (such as lithium strips, lithium foils, or lithium powders) with the negative electrode, and utilize the potential difference between the metallic lithium and the negative electrode to oxidize the metallic lithium into Li +And it diffuses into the negative electrode to achieve prelithiation. For example, Chinese invention patent CN112786971B proposes to compound metallic lithium on the surface of the negative electrode. However, this prelithiation method faces the problem of uneven lithium ion distribution and involves multiple complex operations, increasing the complexity and cost of the production process. Secondly, the high activity of metallic lithium also poses higher requirements for production conditions. The principle of electrochemical prelithiation technology is that in the presence of an electrolyte, an external voltage is applied to cause an electrochemical reaction between the negative electrode and metallic lithium to achieve prelithiation. For example, Chinese patent application with publication number CN112542581A proposes a method for preparing a prelithiation agent through an electrochemical process, but it requires special battery assembly and discharge equipment, and the process is relatively complex, making large-scale production difficult. The principle of continuous electrodeposition prelithiation technology is to use continuous electrodeposition of a metallic lithium layer as a lithium source to achieve continuous preparation of a prelithiated negative electrode. For example, Chinese invention patent CN106702441B proposes a method for preparing a lithium strip with uniform thickness through continuous electrodeposition. However, this method requires high equipment requirements, strict process parameter control, and may also have safety problems. In addition, the above prelithiation technologies cannot improve the structural stability of the negative electrode at the same time.

[0005] In summary, the existing negative electrode prelithiation technologies often have problems such as uneven lithium supplementation, high equipment requirements, and inability to improve the stability of the negative electrode at the same time. Summary of the Invention

[0006] In order to solve the problems of uneven lithium supplementation, high equipment requirements, and inability to improve the stability of the negative electrode at the same time existing in the existing negative electrode prelithiation technologies, the present invention provides a prelithiated phosphorene material, a preparation method thereof, a negative electrode, and a lithium ion battery.

[0007] The present invention is achieved through the following technical solutions:

[0008] The present invention provides a preparation method of a prelithiated phosphorene material, including: adding a lithium salt and phosphorene into a first solvent, ultrasonicating, then centrifuging, filtering the obtained supernatant, and drying the obtained filter cake to obtain the prelithiated phosphorene material.

[0009] The present invention directly prelithiates phosphorene to obtain a prelithiated phosphorene material. The prelithiated phosphorene material can be directly used to prepare the negative electrode of a lithium ion battery, and there is no need to prelithiate the negative electrode through technologies such as supplementing elemental lithium on the surface of the negative electrode, electrochemical prelithiation, or continuous electrodeposition prelithiation, avoiding the need for special equipment and reducing the process complexity of negative electrode prelithiation. At the same time, the present invention directly prelithiates phosphorene, which can greatly improve the uniformity of prelithiation compared with other methods for prelithiating the negative electrode. And, the atoms on the surface of phosphorene are easy to combine with Li + to form Li-P bonds, which can improve the structural stability of the phosphorene negative electrode, inhibit the reaction process between phosphorus on the negative electrode surface and the electrolyte, and reduce the consumption of the electrolyte.

[0010] The preparation method of the prelithiated phosphorene material adopts a solution method for prelithiation, which can achieve uniform prelithiation at the atomic scale, thereby better ensuring the uniformity of the anode prelithiation. Moreover, the method of the present invention is carried out at room temperature, with mild reaction conditions, no need for high-temperature operation, simple process, low cost, low requirements for equipment, and is suitable for large-scale industrial production.

[0011] In the preparation method of the prelithiated phosphorene material of the present invention, the lithium salt is LiNO 3 , LiClO 4 , LiBF 4 , LiPF 6 , lithium bis(oxalato)borate (LiBOB), LiPO 2 F 2 , LiF, Li 2 CO 3 , CF 3 CO 2 Li and Li 2 O, or one or more of them, preferably LiNO 3 , LiPF 6 and LiPO 2 F 2 , more preferably LiNO 3 . The mass ratio of the lithium salt to the phosphorene is (0.1~0.5):1, preferably 0.3:1.

[0012] In the preparation method of the prelithiated phosphorene material of the present invention, the first solvent is one or more of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), ethanol, ethylene glycol, acetonitrile, and acetone, preferably NMP and ethanol, and more preferably NMP.

[0013] In the preparation method of the prelithiated phosphorene material of the present invention, the concentration of the lithium salt in the first solvent is 0.1~3 mol L -1 , preferably 1 mol L -1 .

[0014] In the preparation method of the prelithiated phosphorene material of the present invention, the ultrasonic time is 0.5~5 h, preferably 2 h.

[0015] In some embodiments of the present invention, the preparation method of the prelithiated phosphorene material specifically includes the following steps:

[0016] (1) Under the protection of an inert gas, add the phosphorus material, grinding aid, and grinding balls to the ball mill jar in sequence;

[0017] (2) Select the ball milling method, set the ball milling speed, ball milling time, and number of ball milling times, and carry out the ball milling process under the protection of inert gas;

[0018] (3) Under the protection of inert gas, take out the powder in the ball milling tank to obtain few-layer phosphorene that has been exfoliated;

[0019] (4) Add the phosphorene obtained in step (3) to the first solvent containing lithium salt, perform ultrasonic exfoliation, then centrifuge, and filter the supernatant containing monolayer and few-layer phosphorene by suction filtration. Dry the filter cake obtained by suction filtration to obtain the prelithiated phosphorene material.

[0020] In step (1) of the present invention, the phosphorus material is preferably one or more of red phosphorus powder, black phosphorus powder, and massive black phosphorus. In some more preferred embodiments, the phosphorus material is massive black phosphorus.

[0021] In step (1) of the present invention, the grinding aid is preferably one or more of graphite, silicon dioxide, carbon black, gypsum, talcum powder, coke resin, potassium ferrocyanide, stearic acid, ethanol, ethylene glycol, propylene glycol, diethylene glycol, methanol, glycerol, triethanolamine, diisopropanolamine, oleic acid, lignosulfonate (such as sodium lignosulfonate), polyacrylate (such as polymethyl methacrylate, polyethyl methacrylate), polycarboxylate (such as sodium polyacrylate), and stearate (such as calcium stearate). In some more preferred embodiments, the grinding aid is graphite, ethanol, and ethylene glycol, and more preferably graphite.

[0022] In step (1) of the present invention, the grinding balls are preferably one or more of steel balls, ceramic balls, zirconia balls, and glass balls. In some more preferred embodiments, the grinding balls are steel balls and zirconia balls.

[0023] In step (1) of the present invention, the mass ratio of the phosphorus material to the grinding aid is preferably (85 - 95):1, and the mass ratio of the phosphorus material to the grinding balls is preferably (0.01 - 0.5):1. In some more preferred embodiments, the mass ratio of the phosphorus material to the grinding aid is 90:1, and the mass ratio of the phosphorus material to the grinding balls is 0.02:1.

[0024] In step (2) of the present invention, the ball milling method is one of high-energy swing ball milling, drum ball milling, and plasma ball milling, and high-energy swing ball milling is preferably used.

[0025] In step (2) of the present invention, the ball milling speed is 500 - 1200 rpm, the ball milling time is 0.25 - 1 h, and the number of ball milling times is 5 - 40 times. In some more preferred embodiments, the ball milling speed is 900 rpm, the ball milling time is 0.5 h, and the number of ball milling times is 20 times.

[0026] The present invention also provides a prelithiated phosphorene material prepared by the above method. The prelithiated phosphorene material includes phosphorene and lithium element, and the lithium element forms Li-P bonds with phosphorene.

[0027] The present invention also provides a negative electrode, which includes a current collector and a negative electrode material loaded on the current collector, and the negative electrode material is the above-mentioned prelithiated phosphorene material.

[0028] The preparation method of the negative electrode of the present invention includes: mixing the prelithiated phosphorene material, a conductive agent and a binder, adding them to a second solvent, and stirring to obtain a slurry; coating the slurry on the current collector and drying to obtain the negative electrode.

[0029] In the preparation method of the above negative electrode of the present invention, the mass ratio of the prelithiated phosphorene material, the conductive agent and the binder is (8-9.5):(0.25-1):(0.25-1), preferably 9:0.5:0.5.

[0030] In the preparation method of the above negative electrode of the present invention, the second solvent is one or more of NMP, DMF and ethanol, preferably NMP.

[0031] Specifically, the preparation method of the negative electrode includes:

[0032] 1) After uniformly stirring and mixing the prepared prelithiated phosphorene material, the conductive agent and the binder, adding them to a second solvent and stirring to prepare a slurry;

[0033] 2) Coating the above slurry on the current collector to make an electrode sheet, and drying the electrode sheet to obtain the prelithiated negative electrode.

[0034] In the above step 1) of the present invention, it is preferred to use a stirring and degassing machine for stirring, and the stirring time is 0.25-2 h. For example, the stirring time is 0.5 h.

[0035] In the above step 2) of the present invention, the current collector can be made of copper foil, and the electrode sheet is preferably dried in vacuum. The vacuum drying temperature is 60-120 °C, and the vacuum drying time is 8-24 h; for example, the vacuum drying temperature is 100 °C and the vacuum drying time is 12 h.

[0036] Based on the prepared prelithiated negative electrode, the present invention also provides a lithium-ion battery.

[0037] In some specific embodiments of the present invention, the assembly method of the lithium-ion battery is: in a glove box, using the above-prepared negative electrode as the negative electrode, using metallic lithium as the counter electrode, adding an electrolyte, and assembling a button-type lithium-ion battery.

[0038] The electrolyte is 1.0 M LiPF6 A mixed solution of EC (Ethylene Carbonate) and DEC (Dimethyl Carbonate) with 5.0 wt.% FEC (Fluoroethylene Carbonate) (the volume ratio of EC to DEC is 1:1), or an EC, DEC, and EMC (EthylMethyl Carbonate) mixed solution containing 1.0 M LiPF 6 (the volume ratio of EC, DEC, and EMC is 1:1:1), or an EC, DEC, and EMC mixed solution containing 1.2 M LiPF 6 (the volume ratio of EC, DEC, and EMC is 1:1:1), or an EC and DEC mixed solution containing 1.0 M LiPF 6 (the volume ratio of EC to DEC is 1:1). Preferably, the electrolyte is an EC and DEC mixed solution containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC to DEC is 1:1).

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] In the preparation method of the prelithiated phosphorene material of the present invention, phosphorene is used as the raw material and a lithium salt is used as the lithiating agent, and the reaction is carried out under ultrasonic conditions in a first solvent. The atoms on the surface of phosphorene combine with Li + to form Li-P bonds, thereby obtaining the prelithiated phosphorene material. The present invention uses a solution method to prelithiate phosphorene. On the one hand, uniform prelithiation can be achieved at the atomic scale, so as to better ensure the uniformity of prelithiation of the negative electrode prepared based on the prelithiated phosphorene material; on the other hand, the reaction conditions of the method of the present invention are mild, high-temperature operation is not required, the reaction speed is fast, the process is simple, the cost is low, the requirements for equipment are low, and it is suitable for large-scale industrial production.

[0041] The prelithiated phosphorene material prepared by the present invention is doped with lithium element. When the prelithiated phosphorene material is used to prepare the negative electrode of a lithium-ion battery, the obtained negative electrode itself already contains lithium element. Therefore, it is not necessary to prelithiate the negative electrode by techniques such as supplementing elemental lithium on the surface of the negative electrode, electrochemical prelithiation, or continuous electrodeposition prelithiation, avoiding the need for special equipment and reducing the process complexity of negative electrode prelithiation. At the same time, the distribution of lithium element in the negative electrode prepared based on the prelithiated phosphorene material of the present invention is more uniform. Compared with other methods of prelithiating the negative electrode through subsequent processes, the uniformity of negative electrode prelithiation can be greatly improved. And, the atoms on the surface of phosphorene and Li +After the formation of Li-P bonds, the reaction between the highly active atoms on the surface of phosphorene and the electrolyte during charge and discharge can be avoided, thus achieving the purpose of improving the structural stability of the negative electrode.

[0042] Based on the negative electrode of the pre-lithiated phosphorene material of the present invention, it can itself be used as a pre-lithiated negative electrode, and there is no need to pre-lithiate it through techniques such as supplementing elemental lithium on the surface of the negative electrode, electrochemical pre-lithiation, or continuous electrodeposition pre-lithiation, avoiding the need for special equipment. At the same time, the distribution of lithium elements in the negative electrode based on the pre-lithiated phosphorene material of the present invention is more uniform, which can improve the structural stability of the negative electrode.

[0043] The present invention has assembled a lithium-ion battery based on the negative electrode of the pre-lithiated phosphorene material. The use of the pre-lithiated phosphorene material has improved the cycle stability and lifespan of the lithium-ion battery. The lithium-ion battery can be applied in fields such as new energy vehicles, portable electronic devices, grid energy storage, and energy storage power stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 It is a scanning electron microscope image (SEM image) of the pre-lithiated phosphorene material prepared in Example 2 of the present invention.

[0046] Figure 2 It is an X-ray photoelectron spectroscopy (XPS) diagram of the pre-lithiated phosphorene material prepared in Example 2 of the present invention.

[0047] Figure 3 It is an electrochemical impedance diagram of the lithium-ion batteries assembled in Example 2, Example 8, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention.

[0048] Figure 4 It is a cycle-specific capacity diagram of the lithium-ion batteries assembled in Example 2, Example 8, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention.

[0049] Figure 5 It is a cycle-efficiency diagram of the lithium-ion batteries assembled in Example 2, Example 8, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0050] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0051] It should be noted that the process equipment or devices not specifically noted in the following examples all adopt conventional equipment or devices in the art.

[0052] It should be noted that the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that comprises a series of steps or units does not necessarily limit to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbers of each method step are only convenient tools for identifying each method step, rather than limiting the arrangement order of each method step or the scope in which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in technical content, should also be regarded as the scope in which the present invention can be implemented.

[0053] Example 1

[0054] (1) In an argon glove box, 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls were successively added to a high-energy planetary ball mill jar.

[0055] (2) Connect the power supply of the high-energy planetary ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy planetary ball mill jar on the frame of the high-energy planetary ball mill, and start the high-energy planetary ball mill for high-energy planetary ball milling. The ball milling duration is 10 h.

[0056] (3) Open the high-energy planetary ball mill jar in the argon glove box, take out the powder in the high-energy planetary ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0057] (4) Add 0.1 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the above-obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 2 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0058] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder uniformly at a mass ratio of 9:0.5:0.5, then add them to NMP solvent, and stir for 0.5 h using a stirring and degassing machine to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0059] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01 - 3.0 V (vs. Li / Li + ).

[0060] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 1 is 1583 mA h g -1 , and the capacity retention rate after 50 cycles is 82.2%.

[0061] Example 2

[0062] (1) In an argon glove box, sequentially add 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls to a high-energy swing ball mill jar.

[0063] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball mill jar on the high-energy swing ball mill frame, turn on the high-energy swing ball mill for high-energy swing ball milling, and the ball milling duration is 10 h.

[0064] (3) Open the high-energy swing ball mill jar in the argon glove box, take out the powder in the high-energy swing ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0065] (4) Add 0.3 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 2 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0066] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder uniformly at a mass ratio of 9:0.5:0.5, and then add them to NMP solvent. Stir with a stirring and degassing machine for 0.5 h to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0067] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble it into a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0068] The initial reversible specific capacity of the prelithiated phosphorene material prepared in this Example 2 is 1659 mA h g -1 , and the capacity retention rate after 50 cycles is 86.6%.

[0069] Example 3

[0070] (1) In an argon glove box, sequentially add 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls to a high-energy swing ball mill jar.

[0071] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball mill jar on the high-energy swing ball mill frame, and start the high-energy swing ball mill for high-energy swing ball milling. The ball milling duration is 10 h.

[0072] (3) Open the high-energy swing ball mill jar in the argon glove box, take out the powder in the high-energy swing ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0073] (4) Add 0.4 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 2 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0074] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder evenly according to a mass ratio of 9:0.5:0.5, then add them to NMP solvent, and stir with a stirring degassing machine for 0.5 h to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0075] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0076] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 3 is 1550 mA h g -1 , and the capacity retention rate after 50 cycles is 85.4%.

[0077] Example 4

[0078] (1) In an argon glove box, sequentially add 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls to a high-energy swing ball milling jar.

[0079] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball milling jar on the frame of the high-energy swing ball mill, turn on the high-energy swing ball mill for high-energy swing ball milling, and the ball milling duration is 10 h.

[0080] (3) Open the high-energy swing ball milling jar in an argon glove box, take out the powder in the high-energy swing ball milling jar, and obtain the exfoliated few-layer phosphorene powder.

[0081] (4) Add 0.5 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 2 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0082] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder evenly according to a mass ratio of 9:0.5:0.5, then add them to NMP solvent, and stir for 0.5 h using a stirring and degassing machine to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0083] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble it into a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0084] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 4 is 1575 mA h g -1 , and the capacity retention rate after 50 cycles is 82.3%.

[0085] Example 5

[0086] (1) In an argon glove box, sequentially add 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls to a high-energy swing ball milling jar.

[0087] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball milling jar on the high-energy swing ball mill frame, and start the high-energy swing ball mill for high-energy swing ball milling. The ball milling duration is 10 h.

[0088] (3) Open the high-energy swing ball milling jar in the argon glove box, take out the powder in the high-energy swing ball milling jar, and obtain the exfoliated few-layer phosphorene powder.

[0089] (4) Add 0.3 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 0.5 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0090] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder uniformly at a mass ratio of 9:0.5:0.5, then add them to NMP solvent, and stir with a stirring and degassing machine for 0.5 h to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0091] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0092] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 5 is 1580 mA h g -1 , and the capacity retention rate after 50 cycles is 81.2%.

[0093] Example 6

[0094] (1) In an argon glove box, sequentially add 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls to a high-energy swing ball mill jar.

[0095] (2) Turn on the power of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball mill jar on the high-energy swing ball mill frame, and turn on the high-energy swing ball mill for high-energy swing ball milling. The ball milling duration is 10 h.

[0096] (3) Open the high-energy swing ball mill jar in the argon glove box, take out the powder in the high-energy swing ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0097] (4) Add 0.3 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 3 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0098] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder uniformly according to a mass ratio of 9:0.5:0.5, and then add them to NMP solvent. Stir and degas for 0.5 h using a stirring degassing machine to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0099] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode and metallic lithium as the counter electrode, and add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble it into a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0100] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 6 is 1602 mA h g -1 , and the capacity retention rate after 50 cycles is 83.5%.

[0101] Example 7

[0102] (1) In an argon glove box, sequentially add 1.8 g of bulk black phosphorus, 0.02 g of graphite, and 90 g of grinding balls to a high-energy swing ball mill jar.

[0103] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball mill jar on the high-energy swing ball mill rack, and start the high-energy swing ball mill for high-energy swing ball milling. The ball milling duration is 10 h.

[0104] (3) Open the high-energy swing ball mill jar in an argon glove box, take out the powder in the high-energy swing ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0105] (4) Add 0.3 g of LiNO 3 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 5 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0106] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder evenly according to a mass ratio of 9:0.5:0.5, then add them to NMP solvent, and stir for 0.5 h using a stirring and degassing machine to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0107] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble it into a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0108] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 7 is 1572 mA h g -1 , and the capacity retention rate after 50 cycles is 81.5%.

[0109] Example 8

[0110] (1) In an argon glove box, sequentially add 1.8 g of red phosphorus powder, 0.02 g of ethanol, and 90 g of grinding balls to a high-energy swing ball mill jar.

[0111] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 900 rpm, the one-way intermittent operation time to 30 min, the timing time to 30 min, and the restart times to 19 times. Fix the high-energy swing ball mill jar on the high-energy swing ball mill frame, turn on the high-energy swing ball mill for high-energy swing ball milling, and the ball milling duration is 10 h.

[0112] (3) Open the high-energy swing ball mill jar in the argon glove box, take out the powder in the high-energy swing ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0113] (4) Add 0.3 g of LiPF 6 powder to a sample bottle containing 100 mL of NMP solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine for ultrasonic treatment for 2 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0114] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder evenly according to a mass ratio of 9:0.5:0.5, then add them to NMP solvent, and stir with a stirring degassing machine for 0.5 h to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 100 °C for 12 h.

[0115] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble it into a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0116] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 8 is 1350 mA h g -1 , and the capacity retention rate after 50 cycles is 86.1%.

[0117] Example 9

[0118] (1) In an argon glove box, sequentially add 1.8 g of black phosphorus powder, 0.02 g of ethylene glycol, and 90 g of grinding balls to a high-energy swing ball mill jar.

[0119] (2) Connect the power supply of the high-energy swing ball mill, set the ball milling speed to 1200 rpm, the one-way intermittent operation time to 60 min, the timing time to 60 min, and the restart times to 5 times. Fix the high-energy swing ball mill jar on the high-energy swing ball mill frame, and start the high-energy swing ball mill for high-energy swing ball milling. The ball milling duration is 5 h.

[0120] (3) Open the high-energy swing ball mill jar in an argon glove box, take out the powder in the high-energy swing ball mill jar, and obtain the exfoliated few-layer phosphorene powder.

[0121] (4) Add 0.3 g of LiPO 2 F 2 powder to a sample bottle containing 100 mL of ethanol solvent, stir evenly to obtain a lithium salt solution; take 1 g of the obtained few-layer phosphorene powder, add it to the lithium salt solution, place the sample bottle in an ultrasonic machine and ultrasonic for 2 h, then centrifuge, filter the supernatant by suction filtration, and dry the obtained filter cake. The obtained clean product is the prelithiated phosphorene material.

[0122] (5) Mix the prepared prelithiated phosphorene material, conductive agent, and binder evenly according to a mass ratio of 8:1:1, then add them to NMP solvent, and stir with a stirring and degassing machine for 2 h to prepare a slurry. Coat the slurry on a copper foil to make an electrode sheet, and transfer the electrode sheet to a vacuum drying oven to dry at 120 °C for 8 h.

[0123] (6) In a glove box, use the electrode sheet prepared in step (5) as the negative electrode, use metallic lithium as the counter electrode, add 2 drops of electrolyte (a mixed solution of EC and DEC containing 1.0 M LiPF 6 and 5.0 wt.% FEC (the volume ratio of EC and DEC is 1:1)), and assemble it into a coin-type lithium-ion battery for testing. The test conditions are: the test temperature is 30 °C, the charge-discharge current density is 0.5 A g -1 , and the charge-discharge cut-off voltage is 0.01~3.0 V (vs. Li / Li + ).

[0124] The initial reversible specific capacity of the prelithiated phosphorene material prepared in Example 9 is 1450 mA h g -1 , and the capacity retention rate after 50 cycles is 82.2%.

[0125] Comparative Example 1

[0126] This comparative example is a non-prelithiated phosphorene material. The preparation method and performance test of the phosphorene material are basically the same as those in Example 2, except that: LiNO is not added to the NMP solvent in step (4) 3 powder, that is, the phosphorene is not prelithiated.

[0127] The initial reversible specific capacity of the phosphorene material prepared in this Comparative Example 1 is 1010 mA h g -1 , and the capacity retention rate after 50 cycles is 80.6%.

[0128] Comparative Example 2

[0129] This comparative example uses metallic lithium foil to prelithiate the phosphorene material. The preparation method and performance test of the phosphorene material are basically the same as those in Example 2, except that the prelithiation process in step (4) is: add 1 g of few-layer phosphorene powder and 0.3 g of lithium foil to a crucible in a glove box, and calcine at 350 °C for 2 h to obtain a prelithiated phosphorene material.

[0130] The initial reversible specific capacity of the prelithiated phosphorene material prepared in this Comparative Example 2 is 1251 mA h g -1 , and the capacity retention rate after 50 cycles is 78.3%.

[0131] Comparative Example 3

[0132] In this comparative example, lithium metal powder was used to pre-lithiate the phosphorene material. The preparation method and performance test of the phosphorene material were basically the same as those in Example 2, except that the process of pre-lithiation in step (4) was as follows: 1 g of few-layer phosphorene powder and 0.3 g of lithium powder were added to a glass bottle and mixed evenly in a glove box, and then kept at 100 °C for 24 h to obtain the pre-lithiated phosphorene material.

[0133] The initial reversible specific capacity of the pre-lithiated phosphorene material prepared in this Comparative Example 3 was 1423 mA h g -1 , and the capacity retention rate after 50 cycles was 31.2%.

[0134] Figure 1 is the SEM image of the pre-lithiated phosphorene material prepared in Example 2 of the present invention. As can be seen from Figure 1 , the morphology of the product is a two-dimensional layered structure, indicating that the two-dimensional pre-lithiated phosphorene material was successfully prepared in the present invention.

[0135] Figure 2 is the XPS image of the pre-lithiated phosphorene material prepared in Example 2 of the present invention. The peak located at about 55.5 eV corresponds to Li + , and the peak located at about 133 eV corresponds to P, indicating that the phosphorene material has been successfully pre-lithiated.

[0136] Figure 3 is the electrochemical impedance diagram of the lithium-ion batteries assembled with the pre-lithiated phosphorene materials of Example 2, Example 8, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. As can be seen from the figure, compared with the non-pre-lithiated phosphorene material in Comparative Example 1, the negative electrode prepared with the pre-lithiated phosphorene material in Example 2 has a smaller electrochemical impedance, indicating that pre-lithiation of the phosphorene material is more beneficial to the improvement of the performance of lithium-ion batteries. Compared with the pre-lithiated phosphorene material in Comparative Example 2, the electrochemical impedance of the pre-lithiated phosphorene material prepared in Example 2 of the present invention is smaller, indicating that compared with the pre-lithiation method by calcination, the pre-lithiated phosphorene material obtained by the solution method of the present invention has better electrochemical performance. This is because the solution method for pre-lithiation can achieve uniform pre-lithiation at the atomic scale, thereby improving the uniformity of lithium on the negative electrode and the electrochemical performance of lithium-ion batteries. The pre-lithiated phosphorene material in Comparative Example 3 has the highest electrochemical impedance, even higher than that of the non-pre-lithiated phosphorene material in Comparative Example 1. This is because when using lithium powder as the lithium source for pre-lithiation by the calcination method, the lithium powder agglomerates seriously, which not only fails to play the role of pre-lithiation, but also has a negative impact on the overall performance of the phosphorene material. This shows that whether using lithium powder or lithium foil as the lithium source, the electrochemical performance of the phosphorene material obtained by pre-lithiation by the calcination method is not ideal and is lower than that of the pre-lithiated phosphorene material obtained by the solution method of the present invention, which also shows that the solution method for pre-lithiation used in the present invention is a more effective method.

[0137] Compared with the prelithiated phosphorene material prepared in Example 8, the prelithiated phosphorene material prepared in Example 2 has a smaller electrochemical impedance, indicating that using bulk black phosphorus as the phosphorus source results in a prelithiated phosphorene material with better electrochemical performance.

[0138] Figure 4 It is the cycle-specific capacity diagram of the lithium-ion batteries assembled in Example 2, Example 8, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. It can be seen from the figure that compared with the non-prelithiated phosphorene material in Comparative Example 1, the prelithiated phosphorene material in Example 2 has a higher specific capacity and cycle stability. It can also be seen from the figure that compared with the prelithiated phosphorene material in Comparative Example 2, the prelithiated phosphorene material prepared in Example 2 of the present invention has a higher specific capacity, indicating that compared with the prelithiation method using the calcination method, the prelithiation method using the solution method can obtain a prelithiated phosphorene material with more excellent electrochemical performance, which is consistent with the above results of the electrochemical impedance. At the same time, the prelithiated phosphorene material in Comparative Example 3 has the lowest specific capacity because the lithium powder agglomerates during the calcination process, unable to achieve uniform prelithiation and having an adverse effect on the overall performance of the phosphorene material, which is consistent with the above results of the electrochemical impedance.

[0139] Figure 5 It is the cycle-efficiency diagram of the lithium-ion batteries assembled in Example 2, Example 8, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. It can be seen that compared with the non-prelithiated phosphorene material in Comparative Example 1, the prelithiated phosphorene material in Example 2 has a higher and more stable cycle efficiency, which also indicates that the lithium-ion battery assembled in Example 2 has a more stable negative electrode-electrolyte interface, reducing the occurrence of side reactions and improving the cycle stability. Moreover, the cycle efficiency of the prelithiated phosphorene material in Example 2 is higher than that of the prelithiated phosphorene materials in Comparative Example 2 and Comparative Example 3 because the prelithiation method using the solution method in Example 2 of the present invention makes the distribution of lithium elements in the phosphorene material more uniform, improving the structural stability of the negative electrode while increasing the efficiency of the lithium-ion battery and enhancing the cycle performance of the lithium-ion battery.

[0140] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a pre-lithiated phosphorene material, characterized in that: include: A lithium salt and phosphorene are added to a first solvent, ultrasonicated for 0.5 to 5 h, and then centrifuged. The supernatant is filtered and the filter cake is dried to obtain a pre-lithiated phosphorene material; the lithium salt is one or more of LiNO3, LiClO4, LiBF4, LiPF6, LiBOB, LiPO2F2, LiF, Li2CO3, CF3CO2Li and Li2O.

2. The method for preparing the pre-lithiated phosphorene material according to claim 1, characterized in that: The preparation method of phosphorene is: ball milling a phosphorus material to obtain exfoliated phosphorene; wherein the phosphorus material is one or more of red phosphorus powder, black phosphorus powder and block black phosphorus.

3. The method for preparing the pre-lithiated phosphorene material according to claim 1, characterized in that: The first solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide, ethanol, ethylene glycol, acetonitrile and acetone.

4. The method for preparing the pre-lithiated phosphorene material according to claim 1, characterized in that: The mass ratio of lithium salt and phosphorene is (0.1~0.5):

1.

5. The pre-lithiated phosphorene material obtained by the preparation method according to any one of claims 1 to 4, characterized in that: The invention comprises phosphorene and lithium element, wherein the lithium element and phosphorene form a Li-P bond.

6. A negative electrode, characterized in that It comprises a current collector and a negative electrode material loaded on the current collector, wherein the negative electrode material is the pre-lithiation phosphorene material according to claim 5.

7. The method for preparing the negative electrode according to claim 6, characterized in that: include: The pre-lithiated phosphorene material, the conductive agent and the binder are mixed, added into a second solvent, and stirred to obtain a slurry; the slurry is coated on a current collector, and dried to obtain a negative electrode.

8. A lithium ion battery, characterized in that: Comprising the negative electrode as claimed in claim 6.

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