A Ni x -CoP y O z Nanomaterials and methods of making and using

Abstract

The application belongs to the field of energy storage and materials, and particularly relates to a Ni x -CoP y O z nanomaterial, a preparation method thereof and application thereof. The application develops a method of gamma-ray radiation reduction and heat treatment, and controls growth of Ni x -CoP y O z nanomaterial on a conductive substrate. The Ni x -CoP y O z nanofilm material grown on the CC is used as an anode, a lithium sheet or graphite is used as a cathode, and a Celgard 2035 is used as a diaphragm to assemble a battery, and the potential of lithium deposition is 5.3 mV. The Ni x -CoP y O z nanofilm material prepared by the application has the characteristics of super-lithiophilicity or high lithium combination energy, and application of the metal-free negative electrode as a current collector can make lithium uniformly deposited on the current collector, and further improve the battery capacity and cycle stability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of energy storage materials, and particularly discloses a Ni x -CoP y O z nanomaterial and a preparation method and application thereof. BACKGROUND

[0002] The energy density of a conventional lithium ion battery based on lithium ion intercalation is about 320 Wh / kg, which has been unable to meet the demand of emerging fields for the energy density of lithium batteries. Therefore, lithium batteries known for high energy density have once again attracted extensive attention of researchers as the most potential battery system. Among all lithium batteries, a lithium metal battery without a negative electrode can push the energy density of a full battery to the extreme, exceeds 450 Wh / kg, and is regarded as the ultimate choice of high-energy-density lithium metal batteries. However, compared with lithium batteries containing a negative electrode material, the lithium metal battery without a negative electrode loses the protection of a negative electrode host material or lithium compensation from the negative electrode side, and any irreversible active lithium loss in the cycle process will be directly reflected on the loss of the capacity of the battery, resulting in a lower capacity retention rate of the battery.

[0003] Therefore, how to construct a material with high lithium affinity or high lithium binding energy on the current collector without a metal negative electrode is crucial. SUMMARY

[0004] The application aims to provide a Ni x -CoP y O z nanofilm material and a preparation method and application thereof. The thin film material is prepared by radiation-heating, has excellent lithium affinity and high lithium binding energy, and effectively improves the specific energy and long cycle performance of the battery.

[0005] The technical scheme adopted by the application is as follows:

[0006] In a first aspect, the application provides a preparation method of a Ni x -CoP y O z nanomaterial, wherein Ni represents a nickel metal element, Co represents a cobalt element, P represents a phosphorus element, O represents an oxygen element, x, y and z represent element ratios, and the method specifically comprises the following steps:

[0007] S1, pretreatment of a conductive base material: the conductive base material is ultrasonically washed in a hydrochloric acid solution, water and ethanol alternately for several times; after washing, vacuum drying is performed to obtain the pretreated conductive base material;

[0008] The conductive substrate is selected from any one of the following: carbon cloth (Carbon Cloth CC), carbon paper (Carbon Paper CP), copper foams (Copper Foams CF);

[0009] S2: dissolve the nickel salt, cobalt salt and hypophosphite salt in an alcohol solution and pass inert gas, hang the conductive substrate treated in step S1 in the solution and seal;

[0010] The nickel salt is 1-4 parts by mass, the cobalt salt is 2-8 parts by mass, the hypophosphite salt is 2-8 parts by mass, the concentration of the alcohol solution is 10-50%, and the concentration of the solute is 0.1-0.5 g / mL;

[0011] S3: irradiate the mixed solution containing the conductive substrate obtained in step S2 using γ-rays or electron beams;

[0012] The absorbed dose rate is 10-500 Gy / min, and the absorbed dose is 50-400 kGy;

[0013] S4: wash the substrate obtained in step S3 with water and ethanol alternately for several times, dry and obtain the product;

[0014] S5: place the dried product of step S4 in an inert atmosphere, heat to 200-1000°C and keep constant temperature for 1-5 hours, stop heating, maintain inert atmosphere and cool to room temperature naturally, obtain Ni x -CoP y O z nanomaterial.

[0015] Preferably, in step S1, the thickness of the conductive substrate is not more than 0.5 μm, the concentration of HCl is 0.5-9 mol / L, the ultrasonic power used is 80-100 W, and the vacuum drying temperature is 50-70°C.

[0016] Preferably, in step S2, the nickel salt, cobalt salt and hypophosphite salt are respectively nickel chloride hexahydrate, cobalt chloride hexahydrate and sodium hypophosphite monohydrate.

[0017] Preferably, in step S3, the radiation source of the mixed solution generated by γ-rays is 60Co source or 137Cs source; the electron beam is generated by an electron accelerator, and the energy is 0.1-10 MeV.

[0018] Preferably, in step S4, the drying temperature is 30-70°C.

[0019] Preferably, in step S5, the heating rate is 2-20°C / min.

[0020] Preferably, in steps S1 and S5, the inert gas is selected from high-purity nitrogen or high-purity argon.

[0021] Preferably, the 0.8 <x<1.3,0.8<y<1.2,0.1<z<0.2。

[0022] Secondly, the present invention provides a Ni synthesized by the method described in the first aspect. x -CoP y O z Nanomaterials.

[0023] Thirdly, the present invention provides a Ni as described in the second aspect. x -CoP y O z Nanomaterials are used in the application of anodes in negative electrode-free lithium metal batteries. The lithium battery uses Ni... x -CoP y O z The battery is assembled using a nanofilm material as the anode, a lithium sheet or graphite as the cathode, and a Celgard 2035 separator.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention utilizes gamma-ray radiation reduction and heat treatment to control the growth of Ni on a conductive substrate. x -CoP y O z Nanofilm materials were developed, and these nanofilm materials on conductive substrates were used as negative electrode current collectors in high-energy-density, electrodeless lithium metal batteries. Ni nanofilms were fabricated on the current collectors. x -CoP y O z Nanofilm materials possess unique advantages and broad application prospects in the field of lithium-ion batteries. Their technological advantages mainly lie in the construction of superlithophile or lithium-binding metal element-doped Ni on current collectors without metal anodes. x -CoP y O z Nanofilm materials can uniformly deposit metallic lithium onto the current collector, which can further improve battery capacity and cycle stability. Attached Figure Description

[0026] Figure 1 X-ray diffraction spectra of two different current collectors

[0027] A and B represent CC@Ni0-CoP1O0 and CC@Ni1-CoP1O, respectively. 0.1 .

[0028] The horizontal axis represents twice the X-ray diffraction angle, in degrees, and the vertical axis represents absorbance.

[0029] Figure 2 Electron scanning microscope photos of two different current collectors

[0030] a and b represent CC and CC@Ni1-CoP1O, respectively 0.1 .

[0031] Figure 3 CC@Ni1-CoP1O 0.1 elemental distribution spectrum.

[0032] The horizontal axis is energy in keV, and the vertical axis is intensity in %.

[0033] Figure 4 CC@Ni1-CoP1O 0.1 cobalt (A) and phosphorus (B) distribution spectrum of CC@Ni1-CoP1O.

[0034] The horizontal axis is energy in keV, and the vertical axis is intensity in %.

[0035] Figure 5 Preparation of Ni x -CoP y O z electrode voltage vs. specific capacity curve of CC@Ni1-CoP1O.

[0036] The horizontal axis is capacity in mAh, and the vertical axis is voltage in V. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, but not 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.

[0038] Unless otherwise defined, all the professional terms used in the following have the same meaning as commonly understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application.

[0039] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0040] Embodiment 1

[0041] A lithium battery lithium-free negative electrode current collector Ni x -CoP y O z The nanometer thin film material, its preparation method and its application, the preparation method thereof is as follows:

[0042] 1) Commercial carbon cloth was cut into 20 x 50 mm rectangular pieces, washed with 1 moL / L HCl, distilled water, and ethanol for 5 times by ultrasonic, and dried in a vacuum oven at 60°C overnight after washing. The dried carbon cloth was fixed on rubber plugs for later use.

[0043] 2) First, 2.2 g of CoCl2·6H2O and 4.5 g of NaH2PO2·H2O were added to a test tube containing 50 mL of isopropyl alcohol and ultrapure water in a volume ratio of 1:1. After stirring and dissolving, 1.2 g of NiCl2·6H2O was added, and after stirring and dissolving again, the test tube was placed in a N2 atmosphere to remove air. After 15 min, the test tube was sealed with a rubber plug fixed with CC, and then sent to the cobalt source room for gamma irradiation at a dose rate of 200 Gy / min and an absorbed dose of 200 kGy. The irradiated carbon cloth was taken out and washed with distilled water and ethanol for 5 times, and then dried to obtain the product.

[0044] 3) The product obtained in step 2) was placed in a tube furnace under N2 atmosphere, and heated to 300°C at a heating rate of 5°C / min and kept at this temperature for 2 hours. Then the heating was stopped, and the N2 atmosphere was maintained to cool naturally to room temperature to obtain sample CC@Ni x -CoP y O z , where x = 1, y = 1, and z = 0.1.

[0045] Figure 1 The XRD patterns of CC@Ni0-CoP1O0and CC@Ni1-CoP1O 0.1 were prepared according to the present application. The XRD patterns of CC@Ni0-CoP1O0and CC@Ni1-CoP1O 0.1 respectively showed the characteristic diffraction peaks of CC, CoP, Co2P, and Ni, proving that the Ni-doped Co x P nanomaterials were successfully synthesized on carbon cloth by the combination of gamma-ray irradiation reduction and heat treatment. The CC@Ni x -CoP y O z prepared according to the present application and CC were characterized by SEM, as shown in Figure 2 , CC showed a smooth surface, while the surface of the CC after irradiation-heat treatment was covered with a layer of nanometer thin film material, proving that the Ni x -CoP y O z nanometer thin film material was successfully synthesized on CC. The CC@Ni x -CoP y O z prepared according to the present application was characterized by XPS, and the results are shown in Figure 3 . Figure 3 The diffraction peaks of Ni, Co, O, and P appeared. CC@Nix -CoP y O z The partial spectra of cobalt and phosphorus are as follows Figure 4 As shown, Figure 4 The binding energies of 797.58 and 781.59 eV in A correspond to the 2p binding energies of Co, respectively. 3 / 2 and 2p 1 / 2 The orbital, and the binding energies of 802.39 and 785.40 eV are a pair of satellite peaks, which are characteristic of transition metal elements. Figure 4 B also exhibits chemical bonds of PO and P-Co, indicating that O simultaneously connects to both Co and P, doping into the CoP lattice. This enriches its electron cloud density and increases conductivity. Fitting data shows that Ni... x -CoP y O z x is 1, y is 1, and z is 0.1.

[0046] Ni grown on CC x -CoP y O z The battery is assembled using nanofilm materials, CC as the anode, lithium foil as the cathode, and Celgard2035 separator. Its electrochemical performance is tested using the Wuhan Landian charging / discharging system.

[0047] Figure 5 Ni preparation for the present invention x -CoP y O z As a curve representing the electrode voltage versus specific capacity of the current collector in lithium-ion batteries, under the same current density, Ni x -CoP y O z The potential for lithium deposition is 5.3 mV, while the potential for CC is 15.3 mV, and for Ni... x -CoP y O z The electrode exhibits a low deposition / stripping overpotential, indicating that Ni x -CoP y O z The kinetics of lithium-ion migration in the framework are faster than those in the CC, making it easier for nucleation and growth.

[0048] Example 2

[0049] In step 2 of embodiment 1 60 The Co-γ rays were replaced with an electron beam generated by an electron accelerator, with an absorbed dose rate of 20 kGy / pass and an absorbed dose of 200 kGy. Other conditions were the same as in Example 1, resulting in the CC@Ni sample. x -CoP y O zA nanometer thin film material electrode current collector, wherein x=0.75, y=1, z=0.1, and the potential for depositing lithium is 5.5 mV.

[0050] Example 3

[0051] The absorbed dose rate in step 2) of Example 1 is changed to 10 Gy / min, and other conditions are the same as in Example 1 to obtain sample CC@Ni x -CoP y O z A nanometer thin film material electrode current collector, wherein x=0.8, y=1, z=0.1, and the potential for depositing lithium is 5.9 mV.

[0052] Example 4

[0053] The absorbed dose rate in step 2) of Example 1 is changed to 100 Gy / min, and other conditions are the same as in Example 1 to obtain sample CC@Ni x -CoP y O z A nanometer thin film material electrode current collector, wherein x=0.85, y=1, z=0.1, and the potential for depositing lithium is 6.1 mV.

[0054] Example 5

[0055] The absorbed dose rate in step 2) of Example 1 is changed to 150 Gy / min, and other conditions are the same as in Example 1 to obtain sample CC@Ni x -CoP y O z A nanometer thin film material electrode current collector, wherein x=0.9, y=1, z=0.1, and the potential for depositing lithium is 6.3 mV.

[0056] Example 6

[0057] The absorbed dose rate in step 2) of Example 1 is changed to 250 Gy / min, and other conditions are the same as in Example 1 to obtain sample CC@Ni x -CoP y O z A nanometer thin film material electrode current collector, wherein x=1.1, y=1, z=0.1, and the potential for depositing lithium is 6.7 mV.

[0058] Example 7

[0059] The absorbed dose rate in step 2) of Example 1 is changed to 300 Gy / min, and other conditions are the same as in Example 1 to obtain sample CC@Ni x -CoP y O z A nanometer thin film material electrode current collector, wherein x=1.15, y=1, z=0.1, and the potential for depositing lithium is 6.9 mV.

[0060] Example 8

[0061] The absorbed dose rate in step 2) of Example 1 is changed to 350 Gy / min, and other conditions are the same as Example 1 to obtain sample CC@Ni x -CoP y O z A nanoscale thin film material electrode current collector, wherein x = 1.2, y = 1, z = 0.1, and the potential for depositing lithium is 7.3 mV.

[0062] Example 9

[0063] The absorbed dose rate in step 2) of Example 1 is changed to 400 Gy / min, and other conditions are the same as Example 1 to obtain sample CC@Ni x -CoP y O z A nanoscale thin film material electrode current collector, wherein x = 1.25, y = 1, z = 0.1, and the potential for depositing lithium is 7.5 mV.

[0064] Example 10

[0065] The absorbed dose rate in step 2) of Example 1 is changed to 450 Gy / min, and other conditions are the same as Example 1 to obtain sample CC@Ni x -CoP y O z A nanoscale thin film material electrode current collector, wherein x = 1.3, y = 1, z = 0.1, and the potential for depositing lithium is 7.8 mV.

[0066] Example 11

[0067] The absorbed dose rate in step 2) of Example 1 is changed to 500 Gy / min, and other conditions are the same as Example 1 to obtain sample CC@Ni x -CoP y O z A nanoscale thin film material electrode current collector, wherein x = 1.35, y = 1, z = 0.1, and the potential for depositing lithium is 7.9 mV.

[0068] Example 12

[0069] The absorbed dose in step 2) of Example 1 is changed to 50 kGy, and other conditions are the same as Example 1 to obtain sample CC@Ni x -CoP y O z A nanoscale thin film material electrode current collector, wherein x = 1, y = 0.8, z = 0.1, and the potential for depositing lithium is 7.3 mV.

[0070] Example 13

[0071] The absorbed dose in step 2) of Example 1 was changed to 100 kGy, and the other conditions were the same as in Example 1, and the other conditions were the same as in Example 1, to obtain sample CC@Ni x -CoP y O z A nanomaterial thin film electrode current collector, wherein x = 1, y = 0.85, z = 0.1, and the potential for depositing lithium is 6.8 mV.

[0072] Example 14

[0073] The absorbed dose in step 2) of Example 1 was changed to 150 kGy, and the other conditions were the same as in Example 1, and the other conditions were the same as in Example 1, to obtain sample CC@Ni x -CoP y O z A nanomaterial thin film electrode current collector, wherein x = 1, y = 0.95, z = 0.1, and the potential for depositing lithium is 6.5 mV.

[0074] Example 15

[0075] The absorbed dose in step 2) of Example 1 was changed to 250 kGy, and the other conditions were the same as in Example 1, and the other conditions were the same as in Example 1, to obtain sample CC@Ni x -CoP y O z A nanomaterial thin film electrode current collector, wherein x = 1, y = 1.05, z = 0.12, and the potential for depositing lithium is 6.3 mV.

[0076] Example 16

[0077] The absorbed dose in step 2) of Example 1 was changed to 300 kGy, and the other conditions were the same as in Example 1, and the other conditions were the same as in Example 1, to obtain sample CC@Ni x -CoP y O z A nanomaterial thin film electrode current collector, wherein x = 1, y = 1.1, z = 0.14, and the potential for depositing lithium is 6.0 mV.

[0078] Example 17

[0079] The absorbed dose in step 2) of Example 1 was changed to 350 kGy, and the other conditions were the same as in Example 1, and the other conditions were the same as in Example 1, to obtain sample CC@Ni x -CoP y O z A nanomaterial thin film electrode current collector, wherein x = 1, y = 1.15, z = 0.16, and the potential for depositing lithium is 5.8 mV.

[0080] Example 18

[0081] The absorbed dose in step 2) of Example 1 was changed to 400 kGy, and other conditions were the same as in Example 1, to obtain sample CC@Ni x -CoP y O z A nanometer thin film material electrode current collector, wherein x = 1, y = 1.2, z = 0.18, and the lithium deposition potential is 5.5 mV.

[0082] The above merely describes the embodiments of the present application and is not intended to limit the present application. Based on the above description, those skilled in the art can still make various forms of changes to the technical solutions in the embodiments. Here, it is not necessary and also impossible to give a complete enumeration of all the embodiments. Any modification, change, replacement, etc. made on the basis of the technical content disclosed in the present application shall be included in the protection scope of the present application.

Claims

1. A negative electrode-free lithium metal battery anode Ni x -CoP y O z A method for preparing a nanomaterial, characterized by, Ni represents a nickel metal element, Co represents a cobalt element, P represents a phosphorus element, and O represents an oxygen element, wherein x, y, and z represent element ratios, 0.8 < x < 1.3, 0.8 < y < 1.2, and 0.1 < z < 0.2, and specifically include the following steps: S1: ultrasonic washing of the conductive substrate in a hydrochloric acid solution, water, and ethanol for several times alternately; vacuum drying after washing to obtain a treated conductive substrate; The conductive substrate is selected from any one of the following: carbon cloth, carbon paper, and copper foil; S2: dissolving a nickel salt, a cobalt salt, and a hypophosphite salt in an alcohol solution and passing an inert gas, and suspending the conductive substrate treated in step S1 in the solution and sealing; The nickel salt is 1-4 parts by mass, the cobalt salt is 2-8 parts by mass, the hypophosphite salt is 2-8 parts by mass, the concentration of the alcohol solution is 10-50%, and the concentration of the solute is 0.1-0.5 g / mL; S3: irradiating the mixed solution containing the conductive substrate obtained in step S2 using a gamma ray or an electron beam; The absorption dose rate is 10-500 Gy / min, and the absorption dose is 50-400 kGy; S4: washing the substrate obtained in step S3 with water and ethanol alternately for several times and drying to obtain a product; S5: The product after drying in step S4 is placed in an inert atmosphere, heated to 200~1000 o C and kept constant for 1~5 hours, after stopping heating, keeping inert atmosphere and naturally cooling to room temperature, obtaining Ni x -CoP y O z nanomaterials.

2. The anode of a negative electrode-free lithium metal battery according to claim 1, wherein the Ni x -CoP y O z Method for producing a nanomaterial, characterized in that, The area of the conductive substrate in the step S1 is 20x50 mm, the concentration of HCl is 0.5-9 mol / L, the ultrasonic power used is 80-100 W, and the vacuum drying temperature is 50-70 o C.

3. The anode-free lithium metal battery of claim 1, wherein the Ni x -CoP y O z A method for preparing a nanomaterial, characterized in that, In step S2, the nickel salt, the cobalt salt, and the hypophosphite salt are nickel chloride hexahydrate, cobalt chloride hexahydrate, and sodium hypophosphite dihydrogen monohydrate, respectively.

4. The anode-free lithium metal battery of claim 1, wherein the Ni x -CoP y O z A method for preparing a nanomaterial, characterized by, In step S3, the gamma ray source of the mixed solution is a 60Co source or a 137Cs source; the electron beam is generated by an electron accelerator, and the energy is 0.1-10 MeV.

5. The anode-free lithium metal battery of claim 1, wherein the Ni x -CoP y O z A method for preparing a nanomaterial, characterized by, The drying temperature in the step S4 is 30~70 o C.

6. The anode-free lithium metal battery of claim 1, wherein the Ni x -CoP y O z A method for preparing a nanomaterial, characterized by, The temperature increase rate in the step S5 is 2 to 20 o C / min.

7. The anode-free lithium metal battery of claim 1, wherein the Ni x -CoP y O z A method for preparing a nanomaterial, characterized by, In steps S1 and S5, the inert gas is high-purity nitrogen or high-purity argon.

8. A negative-free lithium metal battery anode Ni synthesized by the method of any one of claims 1-7 x -CoP y O z nanomaterial.

9. A Ni x -CoP y O z Nanomaterials for use in anode of a negative electrode-free lithium metal battery.

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