CN110993919B

CN110993919B - Preparation method and application of potassium ion battery negative electrode energy storage material

Info

Publication number: CN110993919B
Application number: CN201911323701.8A
Authority: CN
Inventors: 闵宇霖; 杜金成; 范金辰; 时鹏辉; 徐群杰
Original assignee: Shanghai Electric Power University
Current assignee: Shanghai Electric Power University
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2022-12-13
Anticipated expiration: 2039-12-20
Also published as: CN110993919A

Abstract

The invention discloses a preparation method of a potassium ion battery cathode energy storage material and application of the potassium ion battery cathode energy storage material in a potassium ion battery. The preparation method comprises the following steps: preparing hydrogel and xerogel precursors; transferring the precursor to a tube furnace for preliminary calcination, and then naturally cooling; taking out the preliminarily calcined product, grinding in a dry environment, pickling and drying; activating the dried sample with KOH milling mixing; transferring the product ground and mixed with the potassium hydroxide into a tubular furnace for calcining; then naturally cooling to room temperature; and (3) pickling the product, finally washing the product to be neutral by using distilled water, deionized water, ultrapure water or ethanol, and drying to obtain the potassium ion battery negative electrode energy storage material with excellent cycle performance. The preparation method is simple, the cost is low, the prepared material has a large specific surface area, and meanwhile, the material has excellent charge-discharge specific capacity, good rate performance and excellent performance, and is suitable for the production of large-scale commercial batteries.

Description

Preparation method and application of potassium ion battery negative electrode energy storage material

Technical Field

The invention relates to a battery material, in particular to a preparation method and application of a potassium ion battery cathode energy storage material with excellent cycle performance, and belongs to the technical field of energy storage materials.

Background

Potassium ion batteries (KIBs) are promising energy storage batteries considered for replacing Lithium Ion Batteries (LIBs). KIBs have a similar basic principle as LIBs, i.e. a "rocking chair" type of energy storage principle, and the natural abundance of potassium is richer than that of lithium, which also provides advantages for further studies of KIBs. Since K +/K (-2.93V) has a redox potential closer to Li +/Li (-3.04V) than Na +/Na (-2.71V), KIBs have a higher voltage plateau and energy density. Notably, studies on KIBs are still in the stage of launch. In addition, unlike sodium ions, potassium ions are large in size (

Ratio of

And

large) resulting in electrochemical properties, such as reversible capacity, lower than LIBs in terms of cycling performance during potassium removal and insertion. Potassium electrolyte has a small interaction and can exhibit higher conductivity than lithium and sodium. This also provides additional advantages for subsequent KIBs development studies. In addition, more energy storage materials are developed for the KIBs, and the key role in prolonging the cycle life and improving the safety performance is played.

Therefore, finding suitable electrode materials to improve the electrochemical performance of KIBs remains a challenge. To solve this problem, different KIBs negative electrode materials have been studied, such as carbonaceous materials graphite, doped graphite, hard carbon, and the like. From a study of these materials we can see the progression of KIBs, and also that short sheets of potassium are present. The electrochemical performance exhibited by these materials is not entirely satisfactory. Due to a large amount of potassium ions and slow kinetics, the potassium ion battery has poor rate performance, low specific capacity and cycling stability. Therefore, it is important to develop new materials with low cost, high capacity and good cycle stability for high performance potassium ion batteries.

This work used super absorbent resin (SAP), a major constituent of urine-absorbent, to carbonize and activate, to obtain high capacity KIBs negative electrode material and label it as SAPC. After carbonization and activation, SAPC exhibits a specific three-dimensional porous nanostructure, and due to its specific structure, K + can be relatively easily embedded in the three-dimensional structure consisting of pores and sheets. The SAPC synthesized by the final test is amorphous carbon, which with short range ordered atoms can increase the interlayer spacing, which allows the carbon layer to accommodate larger K + and allows for volume expansion. After potassium hydroxide activates the carbon material at high temperature, the degree of graphitization increases and the disordered carbon is converted to graphite in a short pathA portion of the aggregation. Shorter layer spacing and unique layering structure can add more K ⁺ Embedded in the carbon layer accommodates increases in interlayer spacing and can withstand volume expansion.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: how to improve the cycle performance of the energy storage material of the negative electrode of the potassium ion battery.

In order to solve the technical problems, the invention is realized by the following technical scheme:

a preparation method of a potassium ion battery negative electrode energy storage material is characterized by comprising the following steps:

step 1): preparing hydrogel: weighing super absorbent resin, placing the super absorbent resin into a reaction kettle, and adding deionized water to carry out pretreatment on gel so as to convert the super absorbent resin into hydrogel which tends to be integrated;

step 2): preparation of xerogel precursor: freezing the prepared hydrogel to obtain ice gel, then putting the ice gel into a freeze drying instrument, and sublimating solid ice to obtain a dry xerogel precursor;

step 3): transferring the precursor to a tube furnace for preliminary calcination, and then naturally cooling;

step 4): taking out the preliminarily calcined product, grinding in a dry environment, pickling and drying;

and step 5): activating the dried sample with KOH milling mixing;

step 6): transferring the product ground and mixed with the potassium hydroxide into a tubular furnace for calcining; then naturally cooling to room temperature;

step 7): and (3) acid-washing the product obtained in the step 6), finally washing the product to be neutral by using distilled water, deionized water, ultrapure water or ethanol, and drying to finally obtain the potassium ion battery cathode energy storage material with excellent cycle performance.

Preferably, the mass ratio of the super absorbent resin to the deionized water in the step 1) is 1: (1-1000).

Preferably, the temperature of the pretreatment in the step 1) is 130-190 ℃, and the reaction time is 1-10 hours.

Preferably, the preliminary calcination in step 3) is performed in a nitrogen or argon atmosphere, the temperature is raised to 550-650 ℃ at a rate of 1-2 ℃/min, and then the temperature is maintained for 1.5-2.5 hours.

Preferably, the temperature adopted by the calcination in the steps 3) and 6) is 400-1000 ℃, the calcination atmosphere adopts helium or argon respectively, the heating rate is 1-10 ℃/min, and the heat preservation time is 15min-5h.

Preferably, the acid washing in the step 4) and the step 7) is performed by using hydrochloric acid, sulfuric acid or nitric acid with a concentration of 0.0001-1 mol/L.

Preferably, in the activation process of the step 5), the mass ratio of KOH to the sample is (20-500): 1, the mass concentration of KOH is 5-30 percent.

The invention also provides the application of the potassium ion battery cathode energy storage material prepared by the preparation method of the potassium ion battery cathode energy storage material in a potassium ion battery.

The functional polymer material absorbs aqueous solution, is pretreated to form hydrogel, converts the hydrogel into ice gel, is frozen and dried to obtain an aerogel precursor, and is subjected to high-temperature calcination, activation and acid pickling to prepare the target active material.

Compared with the prior art, the product prepared by the invention has larger specific surface area, can increase the contact area with electrolyte and promote the diffusion and electronic transition of potassium ions, and when the product is used as a negative electrode material of a potassium ion battery for testing, the prepared product shows reversible high specific capacity, excellent rate capacity and cycling stability, and has the specific advantages that: (1) The three-dimensional porous structure not only provides effective space and path for the storage and transmission of potassium ions and electrons; (2) The huge specific surface area is beneficial to increasing the contact area with the electrolyte, and the active material on the electrode is fully utilized, so that lithium ions fully enter the material in the charging and discharging process; (3) The unique structure can also effectively inhibit the volume expansion change of the electrode material in the charging and discharging processes and prevent agglomeration; (4) Polarization of electrode materials and internal resistance of the battery are reduced, and the cycling stability and the rate capability of the materials are improved; (5) The method for synthesizing the material is simple, has few steps, convenient operation, low price, no toxicity and easy large-scale industrial production.

Compared with other potassium ion battery cathode energy storage materials, the lithium ion battery cathode energy storage material has the advantages of large specific surface area, excellent charge-discharge specific capacity, good rate capability, simple preparation method, low cost and excellent performance, and is suitable for large-scale commercial battery production.

Furthermore, the high-capacity negative electrode material of the energy storage battery can be applied to a potassium ion battery electrode, and shows extremely high potassium storage capacity. The high reversible capacity of 270.4 mAh/g is maintained through 100 cycles at a current density of 50mA/g, and the high cycle stability of 161.7mAh/g is maintained after 2000 cycles when the current density is 1000 mA/g. The excellent performance can be attributed to the unique three-dimensional framework structure and the graphene sheet-like structure after SAP carbonization, and the charge transmission can be accelerated due to the excellent electrochemical performance.

Compared with the prior art, the invention has remarkable technical progress. Compared with the specific capacity of other pure carbon anode energy storage materials, the invention has excellent cycling stability and good rate performance, and the number of cycles can reach 2000. The preparation method is simple, low in cost, excellent in performance and suitable for large-scale commercial battery production.

Drawings

FIG. 1 is a scanning electron microscope image of a SAPC material product obtained in example 1 prior to activation;

FIG. 2 is a scanning electron microscope image of the SAPC material product obtained in example 1 after activation;

FIG. 3 is a scanning electron transmission microscope image of the SAPC material product obtained in example 1;

FIG. 4 is a scanning electron transmission microscope magnified image of the SAPC material product obtained in example 1;

FIG. 5 is a charge and discharge curve of the SAPC material product obtained in example 1;

FIG. 6 is a cyclic voltammogram of the SAPC material product obtained in example 1;

FIG. 7 is a plot of the small current cycle performance of the SAPC material product obtained in example 1;

FIG. 8 is a graph of a rate test of the SAPC material product obtained in example 1;

FIG. 9 is a graph of the large current cycling performance of the SAPC material product obtained in example 1.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

The electrochemical performance of the nitrogen-doped porous carbon negative energy storage material with the long cycle performance obtained in the embodiments 1-5 is tested by an electrochemical workstation and a blue test system; the used electrochemical workstation is Chenghua electrochemical workstation; the blue test system used LAND-CT2001. The electrochemical performance test adopts a 2016 type button cell test, the button cell is assembled in a glove box filled with argon, and the water content value and the oxygen content value in the glove box are both kept below 0.1 ppm.

Example 1

A preparation method of a potassium ion battery cathode energy storage material is characterized by comprising the following steps:

(1) Collecting high-molecular water-absorbent resin particles, weighing 3g of the high-molecular water-absorbent resin particles in a clean beaker, adding the high-molecular water-absorbent resin particles into 60ml of distilled water, oscillating the high-molecular water-absorbent resin particles for 1 hour by using a shaking table, transferring the high-molecular water-absorbent resin particles into a polytetrafluoroethylene-lined reaction kettle after oscillation is finished, preserving heat for 3 hours under the reaction condition of 150 ℃, and converting the high-molecular water-absorbent resin particles obtained through pretreatment into hydrogel which the high-molecular water-absorbent resin particles tend to be integrated;

(2) Then transferring the hydrogel into a refrigerator, freezing the hydrogel into ice gel, freezing the ice gel for 8 hours, and finally drying the sublimed solid ice (namely removing the solvent in the original aqueous solution) by a freeze-drying machine to obtain a dried aerogel precursor;

(3) Transferring the dried aerogel precursor into a tubular furnace, calcining at high temperature, setting the calcining parameters as follows, wherein the initial temperature is 25 ℃, the heating rate is 2 ℃/min, the temperature is raised to 600 ℃, the temperature is kept for 1.5h, and then, naturally cooling and cooling are carried out, wherein the inert gas is nitrogen;

(4) Taking out the product of the primary calcination, grinding in a dry environment, pickling, drying, grinding for 30 min at a pickling concentration of 0.01M hydrochloric acid, washing with distilled water and absolute ethyl alcohol for three times respectively after pickling, and finally vacuum drying at a temperature of 80 ℃;

(5) Mixing and grinding a dried sample and potassium hydroxide (mass ratio is 1;

(6) Performing acid washing (washing by using an acid washing solution and centrifuging) on the product obtained in the step (5), finally washing the product to be neutral by using distilled water, deionized water, ultrapure water or ethanol, and finally performing vacuum drying at the temperature of 80 ℃;

(7) After the product is obtained, it is formulated into a slurry containing a conductive agent, a binder and an organic solvent. The conductive agent is acetylene black, the adhesive is polyvinylidene fluoride (PVDF), the organic solvent is N-methyl pyrrolidone (NMP), then the slurry is coated on a copper foil current collector, and then the battery is assembled in a glove box. And finally, carrying out electrochemical test on the assembled battery in a blue light test system and an electrochemical workstation, carrying out physical characterization on a sample in other aspects, and the like.

Performing electron microscope characterization on the active material, wherein fig. 1 is a scanning electron microscope image before SAPC activation, fig. 2 is a scanning electron microscope image after activation, and fig. 3 and 4 are transmission electron microscope images after activation; FIGS. 5 to 9 are representations of electrochemical properties of the obtained SAPC battery negative electrode material, wherein FIG. 5 is a charge-discharge curve of SAPC at a current density of 50mA/g, FIG. 6 is a cyclic voltammogram of SAPC at the first three times of a voltage range of 0.01-3V and a sweep rate of 0.1mV/s, FIG. 7 is a cyclic performance of SAPC at a current density of 50mA/g, and FIG. 8 is a rate test of SAPC at different current densities. FIG. 9 is a graph of the performance of the resulting potassium ion battery after 2000 cycles at a current density of 1000 mA/g: the characterization of electrochemical properties shows that the product provided by the invention has highly reversible specific capacity when used as a potassium ion battery cathode, is superior to other pure carbon cathode materials of potassium ion batteries reported at present, has excellent electrochemical properties, benefits from the unique large specific surface area structure of SAPC, and can provide a shorter path for potassium ion diffusion and electron transfer.

Example 2

(3) Transferring the dried aerogel precursor into a tubular furnace, calcining at high temperature, setting the calcining parameters as follows, wherein the initial temperature is 25 ℃, the heating rate is 2 ℃/min, the temperature is increased to 550 ℃, keeping the temperature for 1.5h, and then naturally cooling to reduce the temperature, wherein the inert gas is nitrogen;

(4) Taking out the product of the primary calcination, grinding in a dry environment, pickling, drying, grinding for 30 min at a pickling concentration of 0.1M hydrochloric acid, washing with distilled water and absolute ethyl alcohol for three times respectively after pickling, and finally vacuum drying at a temperature of 80 ℃;

(6) Performing acid washing (washing by acid washing solution and centrifuging) on the product obtained in the step (5), finally washing to be neutral by using distilled water, deionized water, ultrapure water or ethanol, and finally performing vacuum drying at the temperature of 80 ℃;

(7) After the sample is obtained, it is prepared into a slurry containing a conductive agent, a binder and an organic solvent. The conductive agent is acetylene black, the adhesive is polyvinylidene fluoride (PVDF), the organic solvent is N-methyl pyrrolidone (NMP), then the slurry is coated on a copper foil current collector, and then the battery is assembled in a glove box. And finally, carrying out electrochemical test on the assembled battery in a blue light test system and an electrochemical workstation, carrying out physical characterization on a sample in other aspects, and the like.

Example 3

(2) Then transferring the hydrogel into a refrigerator, freezing the hydrogel into ice gel, freezing the ice gel for 8 hours, and finally drying the sublimed solid ice by a freeze drying machine (namely removing the solvent in the original aqueous solution) to obtain a dried aerogel precursor;

(3) Transferring the dried aerogel precursor into a tubular furnace, calcining at high temperature, setting the calcining parameters as follows, wherein the initial temperature is 25 ℃, the heating rate is 2 ℃/min, the temperature is increased to 600 ℃, the temperature is kept for 1.5h, then naturally cooling is carried out, and the inert gas is nitrogen;

(4) Taking out the preliminarily calcined product, grinding in a drying environment, pickling, drying, wherein the grinding time is 30 min, the pickling concentration is 0.001M nitric acid, washing with distilled water and absolute ethyl alcohol for three times respectively after pickling, and finally performing vacuum drying at the temperature of 80 ℃;

(7) After the sample is obtained, it is prepared into a slurry containing a conductive agent, a binder and an organic solvent. The conductive agent is acetylene black, the adhesive is polyvinylidene fluoride (PVDF), the organic solvent is N-methyl pyrrolidone (NMP), and then the slurry is coated on a copper foil current collector and then assembled into a battery in a glove box. And finally, carrying out electrochemical test on the assembled battery in a blue light test system and an electrochemical workstation, and carrying out physical characterization on other aspects of the sample.

Example 4

(1) Collecting high-molecular water-absorbent resin particles, weighing 3g of the high-molecular water-absorbent resin particles in a clean beaker, adding 60ml of distilled water, shaking for 1 hour by using a shaking table, transferring the high-molecular water-absorbent resin particles into a polytetrafluoroethylene-lined reaction kettle after shaking is finished, preserving heat for 3 hours under the reaction condition of 150 ℃, and converting the high-molecular water-absorbent resin obtained through pretreatment into hydrogel which tends to be integrated;

(7) After the sample is obtained, it is prepared into a slurry containing a conductive agent, a binder and an organic solvent. The conductive agent is acetylene black, the adhesive is polyvinylidene fluoride (PVDF), the organic solvent is N-methyl pyrrolidone (NMP), then the slurry is coated on a copper foil current collector, and then the battery is assembled in a glove box. And finally, carrying out electrochemical test on the assembled battery in a blue light test system and an electrochemical workstation, and carrying out physical characterization on other aspects of the sample.

Example 5

(4) Taking out the product of the primary calcination, grinding in a dry environment, pickling, drying, grinding for 30 min, pickling with sulfuric acid with the concentration of 1M, washing with distilled water and absolute ethyl alcohol for three times respectively after pickling, and finally vacuum drying at the temperature of 80 ℃;

The invention relates to a lithium ion battery cathode material with ultra-stable cycle performance, which is tested for electrochemical performance through an electrochemical workstation and blue electricity, wherein the electrochemical performance test adopts a 2016 type button cell test, the button cell is assembled in a glove box filled with argon, and the content value of water and the content value of oxygen in the glove box are both kept below 0.1 ppm.

Claims

1. A preparation method of a potassium ion battery negative electrode energy storage material is characterized by comprising the following steps:

step 1): preparing a hydrogel: weighing super absorbent resin, placing the super absorbent resin into a reaction kettle, adding deionized water to carry out pretreatment on gel, wherein the pretreatment temperature is 130-190 ℃, and the reaction time is 1-10 hours, so that the super absorbent resin is converted into hydrogel which tends to be integrated;

and step 3): transferring the precursor to a tube furnace for preliminary calcination, and then naturally cooling;

step 4): taking out the product of the preliminary calcination, grinding in a dry environment, pickling and drying;

and step 5): activating the dried sample with KOH milling mixing;

step 6): transferring a product which is ground and mixed with the potassium hydroxide into a tubular furnace for calcination; then naturally cooling to room temperature;

2. The preparation method of the potassium ion battery negative electrode energy storage material of claim 1, wherein the mass ratio of the super absorbent resin to the deionized water in the step 1) is 1: (1-1000).

3. The method for preparing the energy storage material of the negative electrode of the potassium ion battery as claimed in claim 1, wherein the preliminary calcination in the step 3) is carried out in a nitrogen or argon atmosphere, the temperature is raised to 550-650 ℃ at a rate of 1-2 ℃/min, and then the temperature is maintained for 1.5-2.5 hours.

4. The preparation method of the potassium ion battery negative electrode energy storage material as claimed in claim 1, wherein the calcining in the step 6) adopts 400-1000 ℃, the calcining atmosphere adopts helium or argon respectively, the heating rate is 1-10 ℃/min, and the heat preservation time is 15min-5h.

5. The method for preparing the energy storage material of the potassium ion battery cathode, according to claim 1, characterized in that the acid washing in the step 4) and the step 7) is carried out by hydrochloric acid, sulfuric acid or nitric acid with the concentration of 0.0001-1 mol/L.

6. The preparation method of the potassium ion battery negative electrode energy storage material as claimed in claim 1, wherein during the activation process of the step 5), the mass ratio of KOH to the sample is (20-500): 1.

7. the application of the potassium ion battery negative electrode energy storage material prepared by the preparation method of the potassium ion battery negative electrode energy storage material according to any one of claims 1 to 6 in a potassium ion battery.