CN110611088A

CN110611088A - Lithium ion battery cathode based on organic electrode material and preparation method thereof

Info

Publication number: CN110611088A
Application number: CN201910799093.1A
Authority: CN
Inventors: 刘金章; 闫晓荣
Original assignee: Beijing University of Aeronautics and Astronautics
Current assignee: Beihang University; Beijing University of Aeronautics and Astronautics
Priority date: 2019-08-28
Filing date: 2019-08-28
Publication date: 2019-12-24

Abstract

The invention relates to a negative electrode material of a lithium ion battery based on quinone organic matters, belonging to the field of secondary batteries. The 1, 5-dihydroxynaphthalene with electrochemical activity is attached to the surface of the porous active carbon by an electrochemical polymerization and deposition method to prepare the battery anode. The organic material plays a determining role in its energy storage capacity, voltage window, and electrochemical behavior. The composite anode of the invention is tested by a half-cell, and embodies higher charge-discharge specific capacity and excellent multiplying power and cycle performance. The capacity can be maintained at 320mAh/g after constant current charging and discharging for 250 times. The organic lithium ion battery with high energy density and long cycle life can be prepared by using the poly (1, 5-dihydroxynaphthalene)/porous activated carbon composite material anode provided by the invention.

Description

Lithium ion battery cathode based on organic electrode material and preparation method thereof

Technical Field

The invention relates to selection and preparation of an organic lithium ion battery cathode material, belonging to the field of secondary batteries. The main content is a polymer attached to porous activated carbon, which is prepared by polymerizing and depositing 1, 5-dihydroxynaphthalene and is used for a negative electrode of a lithium ion battery, and the high-quality load of a negative electrode active material can be highlighted. Reversible chemical reactions between the polymer and ions in the organic electrolyte play a key role in energy storage. The negative electrode is combined with a lithium plate, and the voltage window of the formed half cell can reach 3V. The technical method for preparing the cathode of the organic lithium ion battery has four remarkable advantages: (1) the porous activated carbon and the organic electrode material are combined to prepare the cathode, so that the cost is low and the specific capacity is high; (2) the cycle performance is good; (3) the rate capability is good; (4) the voltage window is wide. The method has the advantages of novel material, simple operation and good repeatability, and is suitable for preparing the lithium ion battery with long service life and high power characteristic.

Background

A secondary battery is also called a rechargeable battery or a secondary battery, and refers to a battery that can be continuously used by activating an active material by charging after the battery is discharged. There are four main types of rechargeable batteries: sealing the lead-acid storage battery; a nickel cadmium (NiCd) battery; nickel metal hydride (NiMH) batteries, and lithium ion batteries. In the current battery market, lithium ion batteries dominate. For a long time, the research on negative electrode materials of lithium ion batteries has been focused on inorganic materials, such as graphite, hard carbon, silicon-carbon composite, and the like.

The organic electrode material is a novel energy storage material proposed in recent years, and has the advantages of excellent processability, multi-electron reaction, redox stability, structural diversity and the like. Organic electrode materials are generally classified by functional group, and there are conductive polymers, sulfur-containing compounds, radical compounds, and carbonyl compounds. The carbonyl composite electrode can be divided into three types, and the first type of adjacent carbonyl can form stable enol acid ester through reduction; the second is aromatic carbonyl derivatives; the third type is quinone compound, which can form one additional aromatic system through reduction, and most of quinone electrode material can be used as the negative electrode of organic secondary battery. At present, research on organic negative electrode materials of lithium ion batteries is still in an early stage, and quinone compounds exhibit superior performance in terms of capacity, discharge potential, reaction reversibility, and the like, compared to other organic compounds.

The invention provides an organic cathode material and a preparation method thereof, aiming at an organic lithium ion battery. The electrode material can improve the overall energy storage performance of the lithium ion battery.

Disclosure of Invention

The invention provides a preparation method of an organic lithium ion battery cathode material. The main technical point is the selection and preparation of the cathode material. Will contain porous activated carbon with high specific surface area (specific surface area)Product of large quantities>2000m²Coating the slurry of the/g) on conductive carbon paper or carbon cloth, drying the conductive carbon paper or carbon cloth to be used as a working electrode, and immersing the working electrode into an acid electrolyte dissolved with the micromolecules of the 1, 5-dihydroxynaphthalene. Electrochemically polymerizing 1, 5-dihydroxynaphthalene in a three-electrode electrolytic cell and depositing the electrochemically polymerized product on the inner and outer surfaces of nano-pores of porous active carbon. And (3) carrying out performance test by using a lithium ion half cell assembled by combining a negative electrode based on the poly (1, 5-dihydroxynaphthalene)/porous activated carbon composite material and a lithium sheet. The cathode has the obvious advantages of high capacity per unit area, good cycle performance and low price.

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

a porous nanocarbon powder based substrate was first prepared.

(1) The purchased porous activated carbon powder, polyvinylidene fluoride and acetylene black are dispersed in N-methyl pyrrolidone (NMP) according to the mass ratio of 8:1:1, and then the mixture is magnetically stirred for 24 hours to obtain carbon powder slurry with the concentration of 110 mg/mL.

(2) The carbon powder slurry was uniformly coated on the carbon fiber paper, followed by drying in an oven at 100 ℃ for 12 hours. The mass loading of the carbon powder can be controlled between 2 and 10mg/cm²In the meantime. The carbon fiber paper is commercialized herein as a current collector.

Followed by electrochemical deposition of the polymer.

(3) 1, 5-dihydroxy naphthalene is dissolved in sulfuric acid water solution with certain concentration to prepare electrolyte.

(4) And (3) immersing the conductive carbon paper coated with the porous activated carbon as a working electrode into the electrolyte in step (3), taking a platinum net as a counter electrode, adopting an Ag/AgCl reference electrode, and performing electrochemical deposition at a certain voltage scanning speed (20mV/s) by using cyclic voltammetry so as to polymerize and uniformly deposit the 1, 5-dihydroxynaphthalene molecules in the electrolyte on the porous activated carbon substrate, as shown in figure 1. Voltammetric cycling was performed for 200 and 400 cycles. Therefore, the pseudo capacitance and the ion deintercalation reaction of the polymer can be introduced on the basis of the original electric double layer capacitance of the activated carbon, and the energy storage capacity can be improved by about 4 times. At the same time, the voltage window can also be widened.

And finally, assembling the lithium ion half cell, which comprises the following specific steps:

(6) and (2) taking the poly (1, 5-dihydroxynaphthalene)/activated carbon compound as a positive electrode and a lithium sheet as a negative electrode, assembling the lithium ion half-cell according to the sequence of a negative electrode shell, a spring sheet, a gasket, the lithium sheet, a diaphragm and the positive electrode sheet, dripping electrolyte, and packaging. The effective component of the electrolyte is lithium hexafluorophosphate.

The invention relates to an organic lithium ion battery cathode material, which is characterized in that:

(1) porous activated carbon powder with high specific surface area is selected as a carrier of the polymer. During the electrodeposition process, the polymer not only fills the nanopores, but also adheres to the surface of the carbon particles. Because no thicker block polymer structure is generated, ions in the electrolyte can be easily intercalated in the polymer and have reversible redox reaction with a molecular chain, and polymer molecules are effectively utilized for energy storage.

(2) The lithium ion half-cell is constructed by taking the poly (1, 5-dihydroxynaphthalene)/porous activated carbon composite material as the anode, the voltage window is 0-3V, and when the current density is 0.1A/g, the first discharge specific capacity of the cell exceeds 1200 mAh/g. Under the condition of current density of 0.5A/g, the capacity can be maintained at 320mAh/g after constant current charging and discharging for 250 times.

(3) The lithium ion battery organic cathode material is safe and environment-friendly, has wide sources and high specific capacity; the cycle performance is good; the price is low.

The preparation method of the organic lithium ion battery cathode material provided by the invention discards the traditional inorganic cathode material, and is beneficial to improving the mass loading of active substances on the electrode. The whole preparation process is simple, good in repeatability and low in cost, and is easy to prepare and produce in a large scale, and the requirements of practical application are met.

Drawings

FIG. 1 is a scanning electron microscope image of (1, 5-dihydroxynaphthalene) electrochemically polymerized on the surface of a porous activated carbon coating. (a) Low power plot; (b) high-power map of the surface of individual activated carbon particles.

FIG. 2 shows the constant current charge-discharge curve of the lithium ion half-cell battery constructed by adopting the poly (1, 5-dihydroxynaphthalene)/activated carbon composite material as the anode.

FIG. 3 shows a linear cyclic voltammetry curve of a lithium ion half-cell constructed by using a poly (1, 5-dihydroxynaphthalene)/activated carbon composite material as a positive electrode.

Detailed Description

The present invention is further illustrated by the following examples, but is not limited to the specific embodiments.

(1) And (3) putting the conductive carbon fiber paper into a 60 ℃ oven to be dried for 24 hours for later use.

(2) The specific surface area is 2230m²The porous activated carbon powder, polyvinylidene fluoride and conductive acetylene black are dispersed in N-methyl pyrrolidone (NMP) according to the mass ratio of 8:1:1, and then the mixture is prepared into uniform carbon powder slurry (120mg/mL) which is obtained by magnetic stirring for 24 hours.

(3) Uniformly coating the carbon powder slurry on carbon paper, and then drying in an oven at 100 ℃ for 12 hours to obtain the carbon powder coating with the area loading of 3mg/cm²。

(4) Weighing 1, 5-dihydroxynaphthalene powder, adding into 1M sulfuric acid aqueous solution to prepare solution containing 1, 5-dihydroxynaphthalene with concentration of 0.03M, and using the solution as mother liquor for electrochemical polymerization.

(5) Immersing the conductive carbon paper coated with the porous activated carbon as a working electrode into an acid electrolyte dissolved with 1, 5-dihydroxynaphthalene, taking a platinum net as a counter electrode and Ag/AgCl as a reference electrode, and carrying out electrochemical polymerization on the carbon powder flexible electrode by using a cyclic voltammetry method. Under the voltage scanning rate of 20mV/s and the voltage range of-0.3-1.0V, 200 circles of cyclic voltammetry curve are adopted to obtain the electrode compounded by poly (1, 5-dihydroxynaphthalene) and porous activated carbon, and the electrode is used as the anode of the lithium ion battery.

(6) And assembling the lithium ion half-cell according to the sequence of the cathode shell, the elastic sheet, the gasket, the lithium sheet, the diaphragm and the poly (1, 5-dihydroxynaphthalene)/activated carbon composite material, and performing electrochemical test, wherein the effective component of the electrolyte is lithium hexafluorophosphate.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The invention relates to a lithium ion battery cathode based on an organic electrode material and a preparation method thereof, which are characterized in that the selection and preparation method of the cathode material comprises the following steps:

(1) uniformly mixing the porous active carbon, PVDF and conductive carbon black according to the mass ratio of 8:1:1, and dispersing in an NMP organic solvent to obtain slurry;

(2) uniformly coating the slurry obtained in the step (1) on the surface of carbon fiber paper, and drying to obtain a sample 1;

(3) dissolving 1, 5-dihydroxy naphthalene in an acid electrolyte to obtain a solution 2;

(4) and (3) taking the sample 1 obtained in the step (2) as a working electrode, a platinum net as a counter electrode, Ag/AgCl as a reference electrode and the solution 2 obtained in the step (3) as an electrolyte, performing electrochemical polymerization deposition in a three-electrode electrolytic cell by cyclic voltammetry at a rate of 20-80mV/s for 200 cycles, and attaching the polymerized 1, 5-dihydroxynaphthalene to porous active carbon particles. In the electrodeposition process, the 1, 5-dihydroxynaphthalene can be filled into the nanometer holes of the porous activated carbon and can be attached to the surfaces of carbon particles in a particle form;

(5) and adopting a 1, 5-dihydroxynaphthalene/porous activated carbon composite material anode, a metal lithium cathode, a diaphragm and a lithium hexafluorophosphate electrolyte to form a lithium ion half cell for testing.

2. The negative electrode of the lithium ion battery based on the organic electrode material and the preparation method thereof as claimed in claim 1, wherein the porous activated carbon with high specific surface area is selected in the step (1).

3. The lithium ion battery cathode based on the organic electrode material and the preparation method thereof according to claim 1, characterized in that the carbon fiber paper is selected in the step (2).

4. The negative electrode of lithium ion battery based on organic electrode material and the preparation method thereof as claimed in claim 1, wherein 1, 5-dihydroxynaphthalene is selected in step (3) and its concentration is set.

5. The negative electrode of lithium ion battery based on organic electrode material and the preparation method thereof according to claim 1, wherein the polymer is electrochemically polymerized and deposited by the voltammetry cycling method in the step (4).