CN117416988A - Catkin-based MnO/C composite electrode material, and preparation method and application thereof - Google Patents

Catkin-based MnO/C composite electrode material, and preparation method and application thereof Download PDF

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CN117416988A
CN117416988A CN202311333865.5A CN202311333865A CN117416988A CN 117416988 A CN117416988 A CN 117416988A CN 202311333865 A CN202311333865 A CN 202311333865A CN 117416988 A CN117416988 A CN 117416988A
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catkin
mno
electrode material
composite electrode
lithium ion
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肖姗姗
李英奇
周香港
王立艳
盖广清
赵丽
毕菲
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Jilin Jianzhu University
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Jilin Jianzhu University
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Abstract

Catkin MnO/C composite electrode material, and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The preparation method of the invention comprises the steps of soaking clean catkin in KMnO 4 And (3) separating the catkin after soaking in the solution, sequentially centrifuging with deionized water and absolute ethyl alcohol, and finally vacuum drying the centrifuged catkin, and annealing under the protection of inert atmosphere to obtain the catkin MnO/C composite electrode material. The method takes biological waste catkin as a carbon precursor, takes one-dimensional hollow carbon microtubes derived from catkin as a dispersing agent, and can fully prepare the catkin by a simple one-step pyrolysis methodThe MnO/C composite electrode material for dispersing MnO particles is used for a lithium ion battery, and the lithium ion battery has excellent reversible specific capacity, excellent multiplying power performance and excellent cycle stability due to the unique hollow tubular structure and excellent conductivity of the one-dimensional hollow carbon microtubes derived from catkin.

Description

Catkin-based MnO/C composite electrode material, and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a catkin MnO/C composite electrode material, a preparation method and application thereof, in particular to application of the catkin MnO/C composite electrode material in a lithium ion battery.
Background
Rechargeable Lithium Ion Batteries (LIBs) are widely used in various small electronic devices and electric vehicles due to the advantages of high energy density, long service life and the like.
Graphite has the advantages of low cost, easy production, high cycle efficiency and the like, is applied to LIBs as anode materials for a long time, but has lower theoretical specific capacity (only 372mAh g) -1 ) Limiting its application in the field of high density energy storage.
MnO has high theoretical specific capacity (-756 mAh g) -1 ) The characteristics of abundant reserves, environmental friendliness and the like are paid more attention. However, mnO is very susceptible to agglomeration in practical applications, resulting in lower utilization, and thus the actual capacity of MnO is much lower than its theoretical capacity. At the same time Li + The large stress generated by the large volume expansion/contraction of MnO during the insertion/extraction process causes the MnO to crack or even fall off, which leads to the rapid decay of the capacity and limits the practical application and popularization of the MnO-based anode. In addition, similar to other M x O y (m=ni, co, fe and Cu), mnO is also adversely affected by its inherent low conductivity.
The catkin is a waste as a biomass material, not only can not generate any economic benefit, but also has serious influence on air quality and endangers human health.
Aiming at the problems of MnO and catkin, effective solving measures are needed.
Disclosure of Invention
The invention aims to provide a catkin-based MnO/C composite electrode material and a preparation method thereof, wherein MnO nano particles which are poor in electron and ion transmission performance and easy to agglomerate are densely and uniformly loaded on the inner surface and the outer surface of a catkin-derived one-dimensional hollow carbon microtube by a simple one-step pyrolysis method, the catkin-derived one-dimensional hollow carbon microtube is used as a dispersing agent to inhibit the agglomeration of the MnO nano particles, the utilization rate of the catkin-derived one-dimensional hollow carbon microtube is improved, and the electron and ion transmission performance of MnO is improved by being used as a carbon-based current collector, so that the performance of a lithium ion battery is improved.
The second purpose of the invention is to provide an application of the catkin MnO/C composite electrode material in a lithium ion battery.
The technical scheme adopted by the invention for solving the technical problems is as follows.
The preparation method of the catkin MnO/C composite electrode material comprises the following steps:
soaking clean catkin in KMnO 4 And (3) separating the catkin after soaking in the solution, sequentially centrifuging with deionized water and absolute ethyl alcohol, and finally vacuum drying the centrifuged catkin, and annealing under the protection of inert atmosphere to obtain the catkin MnO/C composite electrode material.
Preferably, the KMnO 4 The concentration of the solution is 0.01-1M.
Preferably, the soaking time is 6-24 hours.
Preferably, the centrifugal rotational speed is 8000-12000rmin -1 The centrifugation time is 5-20min.
Preferably, the vacuum drying temperature is 60-100 ℃ and the vacuum drying time is 8-24h.
Preferably, the annealing temperature is 700-1000 ℃ and the annealing time is 2-10h.
Preferably, the inert atmosphere is Ar.
The invention also provides the catkin MnO/C composite electrode material prepared by the preparation method.
The invention also provides application of the catkin MnO/C composite electrode material in a lithium ion battery.
Preferably, the method comprises the following steps:
firstly, mixing a catkin MnO/C composite electrode material, conductive carbon and a polymer binder in a mass ratio of 8:1:1 into N-methyl pyrrolidone to form slurry, then uniformly coating the slurry on a Cu foil, and carrying out vacuum drying and assembly to obtain the lithium ion battery.
Preferably, the polymeric binder is polyvinylidene fluoride (PVDF).
Preferably, the conductive carbon is acetylene black.
Preferably, the thickness of the Cu foil is 10-30 μm.
Preferably, the drying temperature is 80-120 ℃ and the drying time is 8-24h.
Preferably, the assembling process is as follows: under the protection of argon (O) 2 And H 2 O<1 ppm), 1M LiPF using metallic lithium foil as counter and reference electrode 6 (EC: dec=1:1vol.) was used as electrolyte to assemble CR2025 coin cell.
The invention also provides a lithium ion battery prepared from the catkin MnO/C composite electrode material.
The principle of the invention is as follows: the strategy of the invention is to have M with nanostructure x O y Uniformly loaded on a high-conductivity current collector to form a nano-porous composite electrode, which can utilize M x O y Is a synergistic effect between the high specific capacity of the current collector and the highly conductive network of the current collector. Specifically, the catkin is used as a natural fiber resource, and can be directly pyrolyzed to obtain one-dimensional hollow carbon microtubes, which can provide abundant surface areas as carbon-based current collectors and M x O y Compounding, also can be used as M x O y The dispersant of (2) inhibits agglomeration and improves the utilization rate of the dispersant; in particular, the hollow tubular structure can promote electrolyte mass transfer so as to ensure rapid ion transfer, and the defects of poor ion and electron transfer performance and easy agglomeration of MnO are improved by a method of compounding with one-dimensional hollow carbon microtubes derived from catkin with better conductivity, and meanwhile, the waste catkin is converted into a high-performance carbon-based carrier, so that the purposes ofThe aim of changing waste into valuables is achieved, and the development idea of green and environment protection is met.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, biological waste catkin is used as a carbon precursor, one-dimensional hollow carbon microtubes derived from catkin are used as a dispersing agent, and a simple one-step pyrolysis method is used for preparing the MnO/C composite electrode material capable of fully dispersing MnO particles. The composite electrode material is used for a lithium ion battery, and the lithium ion battery has excellent reversible specific capacity and excellent rate capability (under the current density of 0.1 Ag) due to the unique hollow tubular structure and excellent conductivity of the one-dimensional hollow carbon microtube derived from catkin -1 1365mAh g -1 Even at a high current density of 6.4Ag -1 When the time is kept at 451mAh g -1 ) And excellent cycle stability (at 0.8Ag -1 Hold-100% after 1000 cycles).
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic process diagram of the preparation method of MnO/C composite electrode material of example 1 of the present invention.
FIG. 2 is a graph showing morphology characterization of the MnO/C composite electrode material prepared in example 1 of the present invention, wherein:
(a) A Scanning Electron Microscope (SEM) characterization diagram of the MnO/C composite electrode material;
(b) SEM characterization graph (high power) of MnO/C composite electrode material;
(c) A Transmission Electron Microscope (TEM) characterization diagram of the MnO/C composite electrode material;
(d) Size distribution profile of MnO particles.
FIG. 3 is a Rietveld refinement of XRD patterns of the MnO/C composite electrode material prepared in example 1 of the present invention.
FIG. 4 is a graph showing the chemical composition of MnO/C composite electrode material prepared in example 1 of the present invention, wherein:
(a) Raman spectrum diagram of MnO/C composite electrode material;
(b) FTIR spectrogram of MnO/C composite electrode material;
(c) XPS spectrum of Mn2 p;
(d) TGA profile of MnO/C composite electrode material;
(e) EDS results of C, mn and O in MnO/C composite electrode material; insert: molecular structure of cellulose.
FIG. 5 shows the MnO/C composite electrode material of example 2 of the present invention at 0.01-3V,0.2mV s -1 Cyclic voltammogram for the next four cycles.
FIG. 6 shows the MnO/C composite electrode material of example 2 of the present invention at a current density of 0.1Ag -1 Constant current charge and discharge curve graph of the first four cycles.
FIG. 7 is a graph showing charge/discharge capacity at various current densities of the MnO/C composite electrode material of example 2 of the present invention.
FIG. 8 is a Nyquist plot of the MnO/C composite electrode material of example 2 of the present invention at a frequency ranging from 10mHz to 100 kHz; insert: an enlarged view of the high frequency region EIS.
FIG. 9 shows that the MnO/C composite electrode material of example 2 of the present invention is doped with 0.8Ag -1 The following cycle stability test chart.
FIG. 10 is a graph showing capacitance contribution calculation of MnO/C composite electrode material in example 2 of the present invention:
(a) 0.2, 0.5, 1, 2 and 5mV s within the 0.01-3V voltage window -1 Cyclic voltammogram of MnO/C composite electrode material at scanning rate;
(b) A map of correspondence between logarithms of peak current density and logarithms of scan rate;
(c) MnO/C composite electrode material is 1mV s -1 A capacitance storage contribution graph at the time;
(d) Capacitance contribution graphs of MnO/C composite electrode materials at different scan rates.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below, but it is to be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
The preparation method of the catkin MnO/C composite electrode material comprises the following steps:
soaking clean catkin in KMnO 4 And (3) separating the catkin after soaking in the solution, sequentially centrifuging with deionized water and absolute ethyl alcohol, and finally vacuum drying the centrifuged catkin, and annealing under the protection of inert atmosphere to obtain the catkin MnO/C composite electrode material.
In the technical scheme, KMnO 4 The concentration of the solution is preferably 0.01 to 1M, more preferably 0.1M; the soaking time is preferably 6-24 hours, more preferably 6 hours; the centrifugal rotation speed is preferably 8000-12000rmin -1 More preferably 8000r min -1 The centrifugation time is preferably 5 to 20min, more preferably 5min; the vacuum drying temperature is preferably 60-100deg.C, more preferably 60deg.C, and the vacuum drying time is preferably 8-24h, more preferably 8h; the annealing temperature is preferably 700-1000 ℃, more preferably 700 ℃, and the annealing time is preferably 2-10h, more preferably 6h; the inert atmosphere is preferably Ar.
The invention also provides the catkin MnO/C composite electrode material prepared by the preparation method.
The catkin-based MnO/C composite electrode material can be applied to lithium ion batteries. The specific application method is not particularly limited and may be employed in a manner well known to those skilled in the art. Typically, this is: firstly, mixing a catkin MnO/C composite electrode material, conductive carbon and a polymer binder in a mass ratio of 8:1:1 into N-methyl pyrrolidone to form slurry, then uniformly coating the slurry on a Cu foil, and carrying out vacuum drying and assembly to obtain the lithium ion battery.
In the above technical solution, the polymer binder is preferably polyvinylidene fluoride (PVDF), the conductive carbon is preferably acetylene black, the Cu foil has a thickness of 10 to 30 μm, more preferably 15 μm, the drying temperature is preferably 80 to 120 ℃, more preferably 120 ℃, and the drying time is preferably 8 to 24 hours, more preferably 12 hours.
In the technical scheme, the assembly process is as follows: under the protection of argon gasO 2 And H 2 O<1 ppm), 1M LiPF using metallic lithium foil as counter and reference electrode 6 (EC: dec=1:1vol.) was used as electrolyte to assemble CR2025 coin cell.
In the present invention, the equipment for vacuum drying is usually a vacuum drying oven, and the equipment for annealing is a tube furnace, but there is no particular limitation.
The terms used in the present invention generally have meanings commonly understood by those of ordinary skill in the art unless otherwise indicated.
In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in further detail with reference to examples.
In the following examples, various processes and methods, which are not described in detail, are conventional methods well known in the art. Materials, reagents, devices, instruments, equipment and the like used in the examples described below are commercially available unless otherwise specified.
Example 1
As shown in fig. 1, preparation of catkin-based MnO/C composite electrode material:
soaking 0.2g clean catkin in 0.1M KMnO 4 Adding the solution into a 15mL centrifuge tube for 6h, taking out catkin, centrifuging in the centrifuge at 8000r min -1 Centrifuging for 3 times in deionized water and 2 times in absolute ethyl alcohol, taking out the catkin, drying for 8 hours at 60 ℃ in a vacuum drying oven, and finally annealing the dried catkin in a tubular furnace, and keeping for 6 hours at 700 ℃ under Ar protection to obtain the catkin-based MnO/C composite electrode material.
The MnO/C composite electrode material prepared in example 1 was characterized and the results are shown in FIGS. 2 to 4.
The surface morphology of the MnO/C composite electrode material was observed by Scanning Electron Microscopy (SEM), as shown in FIG. 2. From fig. 2, it can be seen that MnO particles are densely and uniformly distributed on the inner and outer surfaces of the one-dimensional hollow carbon microtube derived from catkin. The hollow tubular structure provides a fast path for the transport of electrons and ions and sufficient space to absorb more of the electroactive MnO. SEM combined with TEM analysis revealed that MnO particles had an average diameter of 170nm and were packed with nanoparticles having a diameter of about 15 nm.
The crystal structure of the MnO/C composite electrode material was further determined by X-ray diffraction analysis. As shown in FIG. 3, the diffraction peak positions of the samples were matched with MnO (JCPDS 78-0424) standard cards. The XRD pattern is well matched with the calculated data, and the difference is negligible, so that the prepared sample is truly MnO/C composite electrode material without any impurity.
As shown in FIG. 4, the MnO/C composite electrode material was characterized by Raman, FTIR, XPS, TGA and EDS, and the composite electrode material was confirmed to be the MnO/C composite electrode material. As shown in FIG. 4 (a), the Raman spectrum of MnO/C has two distinct characteristic peaks, crystalline graphite E 2g The G band of modes and the D band associated with disordered carbon, edges and other defects. In addition, the strength of G is obviously stronger than that of D, which shows that the content of crystalline graphite carbon in the MnO/C composite electrode material is higher, thereby being beneficial to improving the conductivity of MnO. Fourier Transform Infrared (FTIR) spectroscopy was used to examine the composition changes that occurred during the synthesis. As shown in FIG. 4 (b), at 773, 1011, 1369 and 1436cm -1 The 4 absorption peaks of (2) correspond to the vibrations of Mn-O bonds of MnO particles, which are uniformly distributed on the surface of the carbon tube. As shown in FIG. 4 (c), the XPS spectrum of Mn2p has two main peaks around 642.13eV and 642.0eV, and the spin energy is separated into Mn2p of 11.90eV, which is MnO phase respectively 1/2 And Mn2p 3/2 Is a typical characteristic peak of (a). The composition of MnO/C in air was studied by thermogravimetric analysis (TGA) to reveal the carbon content. As shown in FIG. 4 (d), the weight loss from room temperature to 250℃was about 13.3%, which was attributed to the evaporation of water in MnO/C. In the range of 250-700 c, with increasing temperature, the weight loss was about 57.6% due to the combustion of carbon to CO 2 . The elemental content of C, mn and O in the MnO/C composite electrode material measured by cellulose structure and Energy Dispersive Spectroscopy (EDS) is shown in fig. 4 (e), and the measurement results confirm the presence of C, mn and O in the sample. The molar ratio of Mn to O is 0.73, which is relatively consistent with the stoichiometric ratio of MnO.
Example 2
Preparation of a lithium ion battery:
the catkin-based MnO/C composite electrode material (prepared in example 1), acetylene black and polyvinylidene fluoride in a mass ratio of 8:1:1 were mixed into N-methylpyrrolidone to form a slurry, the slurry was then uniformly coated on a 15 μm thick Cu foil, and dried in a vacuum oven at 120℃for 12 hours, and finally, the mixture was filled with argon (O) 2 And H 2 O<1 ppm) in a glove box, 1M LiPF with metallic lithium foil as counter and reference electrode 6 (EC: dec=1:1vol.) was used as electrolyte to assemble CR2025 coin cells.
Electrochemical test of CR2025 button cell prepared in example 2, cyclic voltammetry scan was performed at a cyclic voltammetry characteristic curve ranging from 0.01 to 3V and a scan rate of 0.2 to 5mV s -1 . In the constant current charge and discharge test, the voltage interval is set to 0.01-3V and the current intensity is 10-640 mu A. In the impedance test, the frequency range was set to 100kHz to 10mHz, and the voltage amplitude was 10mV. When the constant current charge and discharge is used for the cycle stability test, the voltage interval is set to be 0.01-3V, and the current density is set to be 0.8Ag -1 The number of cycles was 1000.
The results of the electrochemical performance test are shown in fig. 5 to 10.
MnO/C composite electrode material is 0.2mV s -1 The first four cycles of Cyclic Voltammetry (CV) curves of (a) are shown in fig. 5, and the change in peak position of the second cycle compared to the first cycle is due to the formation of a solid-electrolyte interfacial film (SEI) on the electrode. The CV curves overlap to a large extent over 2-4 cycles, indicating excellent reversibility of the electrode during repeated electrochemical cycles.
As shown in fig. 6, the electrode exhibits extremely high reversible capacity. The ultra-high reversible charge/discharge capacity is mainly attributed to the well-integrated anode (in situ growth of MnO particles) which helps to rapidly migrate ions/electrons throughout the matrix.
As shown in fig. 7, the MnO/C composite electrode material has excellent rate capability, and can realize deep charge and discharge at high current density.
As shown in fig. 8, the impedance data shows that the inherent resistance of the electrode is 5.13 ohms before cycling and 7.22 ohms after cycling, and the lower resistance is beneficial to the transmission of electrons and ions, so that the utilization rate of MnO is improved. The resistance change before and after cycling was small, indicating that the structure of the electrode was stable.
The cycling stability of the electrode was further verified by long-time charge and discharge, as shown in FIG. 9, after 1000 cycles, the capacity was maintained at 1941mAh g -1 Exhibits excellent lithium storage capacity and excellent cycle stability. The coulombic efficiency of the electrode was maintained at a level near 100% throughout the cycle.
As shown in FIG. 10, the utilization rate of MnO in the MnO/C composite electrode material is further calculated to be 90.8% by the capacitance contribution of the electrode, and the high utilization rate is attributed to the fact that the one-dimensional hollow carbon microtubes derived from the catkin are used as the dispersing agent to effectively inhibit aggregation of MnO particles, and the actual capacity of MnO is improved.
It should be apparent that the above embodiments are merely examples for clarity of illustration and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. The preparation method of the catkin MnO/C composite electrode material is characterized by comprising the following steps:
soaking clean catkin in KMnO 4 And (3) separating the catkin after soaking in the solution, sequentially centrifuging with deionized water and absolute ethyl alcohol, and finally vacuum drying the centrifuged catkin, and annealing under the protection of inert atmosphere to obtain the catkin MnO/C composite electrode material.
2. The method for preparing the catkin based MnO/C composite electrode material according to claim 1, wherein the KMnO comprises the following steps of 4 The concentration of the solution is 0.01-1M.
3. The method for preparing a catkin based MnO/C composite electrode material according to claim 1, wherein the soaking time is 6-24 hours.
4. The method for preparing the catkin based MnO/C composite electrode material according to claim 1, wherein the centrifugal rotation speed is 8000-12000rmin -1 The centrifugation time is 5-20min.
5. The preparation method of the catkin-based MnO/C composite electrode material according to claim 1, characterized in that,
the vacuum drying temperature is 60-100 ℃, and the vacuum drying time is 8-24 hours;
the annealing temperature is 700-1000 ℃ and the annealing time is 2-10h;
the inert atmosphere is Ar.
6. The catkin-based MnO/C composite electrode material prepared by the preparation method according to any one of claims 1 to 5.
7. The use of the catkin MnO/C composite electrode material according to claim 6 in lithium ion batteries.
8. The application of the catkin MnO/C composite electrode material in a lithium ion battery according to claim 7, wherein the catkin MnO/C composite electrode material, conductive carbon and a polymer binder with the mass ratio of 8:1:1 are mixed into N-methyl pyrrolidone to form slurry, and then the slurry is uniformly coated on a Cu foil, dried in vacuum and assembled to obtain the lithium ion battery.
9. The use of the catkin based MnO/C composite electrode material according to claim 8 in lithium ion batteries,
the polymer binder is polyvinylidene fluoride;
the conductive carbon is acetylene black;
the thickness of the Cu foil is 10-30 mu m;
the drying temperature is 80-120 ℃ and the drying time is 8-24h;
the assembly process is as follows: under the protection of argon, using metal lithium foil as counter electrode and reference electrode, 1MLiPF 6 As an electrolyte, a CR2025 coin cell was assembled.
10. A lithium ion battery made using the catkin based MnO/C composite electrode material of any one of claims 1-5.
CN202311333865.5A 2023-10-16 2023-10-16 Catkin-based MnO/C composite electrode material, and preparation method and application thereof Pending CN117416988A (en)

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