CN105789602A - Preparation method of zinc oxide nanosheet for negative electrode of lithium-ion battery - Google Patents

Abstract

The invention provides a preparation method of a zinc oxide nanosheet for a negative electrode of a lithium-ion battery. The method comprises the following steps: (1) dissolving zinc acetate into deionized water as a precursor at a room temperature; (2) sequentially adding sodium citrate and sodium hydroxide to the solution prepared in the step (1) for stirring for 1-12 hours; (3) adding hexamethylenetetramine to the solution obtained in the step (2) and stirring and dissolving the hexamethylenetetramine, wherein the molar ratio of the zinc acetate to the sodium citrate to the sodium hydroxide to the hexamethylenetetramine is 1 to (1.8-2.1) to (1.8-2.1) to 1; and (4) transferring the solution into a reaction kettle, heating the solution to 120-160 DEG C, carrying out heat preservation for 10-48 hours, cooling the solution to a room temperature after reaction is ended, and filtering and collecting the solution to obtain a target material. The preparation method is simple to operate and low in cost; the zinc oxide nanosheet can be obtained through a one-step hydrothermal synthesis method; the contact area of the obtained zinc oxide nanosheet and an electrolyte is large; and the lithium-ion battery has relatively good electrochemical properties.

Description

A kind of preparation method of the Zinc oxide nano sheet that can be used for lithium ion battery negative

Technical field

The present invention relates to the preparation method of a kind of Zinc oxide nano sheet lithium ion battery negative material, belong to nano material and prepare and new Energy device field.

Background technology

Along with developing rapidly of communication technology and computer technology, the various electronic product such as mobile phone, notebook computer all towards " light, Thin, short, little " target stride forward, electric automobile, space industry and sophisticated weapon equipment non-to the demand of high-performance secondary cell Often urgent, the demand in high-tech market promotes the development of secondary cell, and novel secondary battery technology is counted as 21 century and has war The slightly dual-use technology of meaning.The key factor affecting performance of lithium ion battery is exactly negative material.The most business-like Lithium ion battery many employings graphite, as negative material, also exists relatively low (the 372mAh g of capacity^-1), the deficiency such as cryogenic property is poor, It is desirable that prepare the lithium cell cathode material that performance is the most excellent.Many researchers are just being devoted to develop Novel anode material, Such as SnO₂、MoS₂With transition metal oxide etc..In these materials, nanocrystalline transition metal oxide is owing to possessing Gao Li Opinion capacity and high security are it is considered to be the preferable negative material of lithium ion battery of future generation.

Zinc oxide (ZnO) is 978mAh g as theoretical capacity during lithium ion battery negative material^-1, in lithium ion battery, Zinc oxide shows higher theoretical capacity and preferable cyclical stability.The reaction of its reversible electrochemical can be expressed as follows:

$ZnO+2{\mathrm{Li}}^{+}+2e^{-}\↔Zn+{\mathrm{Li}}_{2}O$

$Zn+{\mathrm{Li}}^{+}+e^{-}\↔LiZn$

According to the state of material, the preparation method of nano zine oxide can be divided into: solid phase method, liquid phase method and vapour deposition process.Gu Phase method is that after metal-oxide or slaine being mixed by a certain percentage, grinding is calcined, and then occurs solid state reaction directly to prepare nanometer Powder.The granule that this method generates is easier to reunite, it usually needs again pulverize；Vapour deposition process requires at depositing temperature Under, reactant must have sufficiently high vapour pressure；The product of reaction, in addition to required deposit is solid film, its More than must be all gaseous state；Liquid phase method can accurately control the chemical composition of particle, and has that raw material is easy to get, equipment is simple, grain Sub-size is concentrated, shape and crystal structure is easily controlled, batch is big, its lytic activity is good and the feature of low cost.Liquid phase method is permissible It is divided into sol-gel process, hydrothermal synthesis method, the sedimentation method, microemulsion method, solvent evaporated method etc..Wherein, hydrothermal synthesis method be with Water is solvent, and under uniform temperature and pressure, original stock carries out the synthetic technology reacted in hermetic container.High at high temperature In the environment of pressure, the nucleation of particle and the speed of growth are very fast, and the most this technology is the most suitably prepared and had specific crystal structure Crystal.Such as, CN101597080B reports a kind of olive-shaped zinc oxide that can be used for cathode of lithium battery and core-shell structure oxidation The preparation method of zinc-zinc peroxide micron particle, is dissolved in zinc nitrate in dehydrated alcohol, with lithium chloride as mineralizer, 140-200 DEG C of solvent heat treatment, obtains white particle olivary ZnO micron negative material；With olivary ZnO as forerunner Body, under the hydrothermal condition that there is hydrogen peroxide, obtains the olivary ZnO/ZnO of granule₂Micron negative material.But, its system There is the highest (≤1020mAh g of discharge capacity first in standby zinc oxide lithium cell cathode material^-1), cycle performance is poor, electric conductivity The defect such as relatively low；CN103647048B reports the preparation method of a kind of high rate lithium ionic cell cathode material, by macromolecule Polymer, zinc salt and conducting medium precursor salt are dissolved in N-N-dimethylformamide (DMF) solution, continuously stirred make It is completely dissolved, the transparent shape of solution, then gained clear solution is moved to electrospinning device, carries out electrostatic under high voltages Spinning is sprayed, and treats solution injection completely, takes the thin film collected off, be transferred to vacuum drying oven and be dried process from aluminium foil, The stage that is undertaken in two steps by dried product heats up.Question response is cooled to room temperature after terminating, take out product and be zinc oxide/conduction Medium/carbon nano-fiber.But, its preparation method is loaded down with trivial details, first the highest (≤1200mAh g of discharge capacity^-1).Above method The shortcoming existed causes zinc oxide lithium cell cathode material to be difficult in actual production extensively applying.The present invention try hard to overcome above-mentioned specially The shortcoming that profit technology exists, utilizes citrate ion with the feature of negative charge, is combined generation sheet zinc oxide with zinc ion, The preparation method of the nano zine oxide lithium cell cathode material of a kind of low cost, height ratio capacity is provided, is that one utilizes a step water Full-boiled process prepares the method for Zinc oxide nano sheet.

Summary of the invention

It is an object of the invention to the deficiency for current techniques, utilize one step hydro thermal method synthesizing zinc oxide nanometer sheet.The method has Height simple to operate, repeatable, feature with low cost, and prepare Zinc oxide nano sheet Stability Analysis of Structures, epigranular, Pattern is easy to control.This Zinc oxide nano sheet as the negative material of lithium ion battery, overcome zinc oxide discharge capacity first low, The problem such as poorly conductive, Volumetric expansion, and have that cyclical stability is strong, the feature of good conductivity.

The technical scheme is that

The preparation method of a kind of Zinc oxide nano sheet that can be used for lithium ion battery negative, comprises the steps:

(1) zinc acetate is at room temperature dissolved in deionized water as presoma；

(2) sodium citrate and sodium hydroxide are added sequentially in the solution of step one stirring 1-12 hour；

(3) addition hexamethylenetetramine, stirring and dissolving in the solution obtained the most upwards are walked；

Wherein, molar ratio of material is zinc acetate: sodium citrate: sodium hydroxide: hexamethylenetetramine=1:1.8～2.1:1.8～2.1: 1；

(4) proceed to reactor, be heated to 120-160 DEG C, be incubated 10～48 hours；After reaction terminates, it is cooled to room temperature, mistake Filter, collects, obtains target material.

The invention have the benefit that

The present invention is simple to operate, and one step hydro thermal method synthetic method can obtain Zinc oxide nano sheet, the Zinc oxide nano sheet obtained and electricity (zinc oxide is lamellar to the contact area of solution liquid as can be seen from Figure 3, and the length of side is about about 500nm, has big contact surface greatly Long-pending), the beneficially migration of lithium ion, embed and deintercalation, effectively improve the cycle performance of lithium ion battery, improve initial discharge Capacity, makes lithium ion battery possess more preferable chemical property.In embodiment 1, as shown in Figure 4, in the multiplying power of 0.1C Under, its first discharge capacity up to 1705mAh g^-1, and after 100 circulations, discharge capacity still can keep 373mAh g^-1.And Disclosed in CN105118975A, Zinc oxide nanoparticle lithium ion battery negative material is under the multiplying power of 0.1C, and it discharges first Capacity only reaches 1652mAh g^-1, after 100 circulations, discharge capacity is only 318mAh g^-1。

Nanometer sheet has the architectural feature different from other nano material and surface characteristic, shows bright as electrode material of lithium battery Aobvious advantage, is embodied in:

(1) flaky nanometer zinc oxide is perpendicular or tilts state and piles up at an angle, as shown in Figure 3, and these nanometer sheet Arrangement is not closely, has fully connecing of certain space, so beneficially active material and electrolyte each other Touch, therefore can increase effective electrochemical reaction area, improve the utilization rate of active substance.

(2) contact area of flaky nanometer zinc oxide and electrolyte is big, and contact area is the biggest, is more beneficial to the diffusion of lithium ion, and receives Rice sheet is the thinnest, and this structure can reduce lithium ion abjection and the distance embedded, and increases diffusion rate, reduces lithium simultaneously The structural deterioration that ion embeds and during abjection, change in volume causes, thus improve the cycle performance of material.

(3) flaky nanometer zinc oxide has good plasticity, can stand the shape strain and stress that electrochemical process causes, in discharge and recharge In journey, the stereomutation of himself is little, and the deformation energy of electrode accesses effective suppression, and its chemical property is also than other The zinc oxide of pattern is more stable.

Accompanying drawing explanation

Fig. 1 is the route artwork of the present invention；

Fig. 2 is X-ray diffraction (XRD) figure of the Zinc oxide nano sheet obtained by the embodiment of the present invention 1；

Fig. 3 is scanning electron microscope (SEM) figure of the Zinc oxide nano sheet obtained by the embodiment of the present invention 1；

Fig. 4 is Zinc oxide nano sheet obtained by the embodiment of the present invention 1 as cathode of lithium battery cyclic curve figure under 0.1C multiplying power；

Detailed description of the invention

Embodiment 1

1) zinc acetate of 5mmol is placed in 70mL deionized water, dissolves under magnetic stirring；

2) after zinc acetate is completely dissolved, add 10mmol sodium citrate 10mmol sodium hydroxide, stir 1 hour；

3) 5mmol hexamethylenetetramine joining the solution in step 2, stirring is to dissolving；

4) proceed in the reactor of 100ml, be heated to 120 DEG C, be incubated 12 hours；

5) after reaction terminates, it is cooled to room temperature, filters, collect, obtain zinc-oxide nano sheet material；

6) it is 7: 2: 1 by prepared zinc-oxide nano sheet material and conductive agent acetylene black and binding agent Kynoar according to mass ratio Ratio is placed in mortar, and ground and mixed is uniform, instills N-methyl pyrrolidinone solvent and is ground to pulpous state, is uniformly scratched by slurry On Copper Foil, at 60 DEG C, it is dried 12h, uses tablet machine to depress to thin slice at 5MPa pressure, obtain anode plate for lithium ionic cell.Will Gained zinc oxide negative plate, metal lithium sheet, battery case, barrier film, pad and spring leaf are placed in the glove box of full argon Row battery assembles, and obtains button CR2025 half-cell.

Prepared zinc oxide sample carries out XRD (XRD, smart Lab, Rigaku company produces) analyze.Such as accompanying drawing 2 Shown in, sample belongs to zincite (a=0.3249nm, c=0.5206nm, JCPDS 36-1451).It is not detected by impurity peaks, Show to synthesize and obtain pure oxidized zinc products.

Prepared zinc oxide sample carries out SEM (SEM, S-4800, Hitachi Ltd produces) analyze.Such as accompanying drawing 3 institute Showing, the Zinc oxide nano sheet thickness of synthesis is uniform, about about 85nm.

Prepared zinc oxide sample is carried out chemical property analysis (BTS-5V5mA, new prestige).As shown in Figure 4, exist Under the multiplying power of 0.1C, its first discharge capacity up to 1705mAh g^-1, and after 100 circulations, discharge capacity still can keep 373 mAh g^-1。

Embodiment 2

1) zinc acetate of 6mmol is placed in 70mL deionized water, dissolves under magnetic stirring；

2) after zinc acetate is completely dissolved, add 10.8mmol sodium citrate 10.8mmol sodium hydroxide, stir 4 hours；

3) 6mmol hexamethylenetetramine joining the solution in step 2, stirring is to dissolving；

4) proceed in the reactor of 100ml, be heated to 150 DEG C, be incubated 12 hours；

5) after reaction terminates, it is cooled to room temperature, filters, collect, obtain zinc-oxide nano sheet material；

6) it is 7: 2: 1 by prepared zinc-oxide nano sheet material and conductive agent acetylene black and binding agent Kynoar according to mass ratio Ratio is placed in mortar, and ground and mixed is uniform, instills N-methyl pyrrolidinone solvent and is ground to pulpous state, is uniformly scratched by slurry On Copper Foil, at 60 DEG C, it is dried 12h, uses tablet machine to depress to thin slice at 5MPa pressure, obtain anode plate for lithium ionic cell.Will Gained zinc oxide negative plate, metal lithium sheet, battery case, barrier film, pad and spring leaf are placed in the glove box of full argon Row battery assembles, and obtains button CR2025 half-cell.

Zinc oxide nano sheet thickness approximates with embodiment 1 also about 85nm, XRD result, electrochemical performance data.

Embodiment 3

1) zinc acetate of 7mmol is placed in 70mL deionized water, dissolves under magnetic stirring；

2) after zinc acetate is completely dissolved, add 14.7mmol sodium citrate 14.7mmol sodium hydroxide, stir 2 hours；

3) 7mmol hexamethylenetetramine joining the solution in step 2, stirring is to dissolving；

4) proceed in the reactor of 100ml, be heated to 160 DEG C, be incubated 15 hours；

5) after reaction terminates, it is cooled to room temperature, filters, collect, obtain zinc-oxide nano sheet material；

6) it is 7: 2: 1 by prepared zinc-oxide nano sheet material and conductive agent acetylene black and binding agent Kynoar according to mass ratio Ratio is placed in mortar, and ground and mixed is uniform, instills N-methyl pyrrolidinone solvent and is ground to pulpous state, is uniformly scratched by slurry On Copper Foil, at 60 DEG C, it is dried 12h, uses tablet machine to depress to thin slice at 5MPa pressure, obtain anode plate for lithium ionic cell.Will Gained zinc oxide negative plate, metal lithium sheet, battery case, barrier film, pad and spring leaf are placed in the glove box of full argon Row battery assembles, and obtains button CR2025 half-cell.

Zinc oxide nano sheet thickness approximates with embodiment 1 also about 85nm, XRD result, electrochemical performance data.

Embodiment 4

1) zinc acetate of 7.5mmol is placed in 70mL deionized water, dissolves under magnetic stirring；

2) after zinc acetate is completely dissolved, add 15mmol sodium citrate 15mmol sodium hydroxide, stir 6 hours；

3) 7.5mmol hexamethylenetetramine joining the solution in step 2, stirring is to dissolving；

4) proceed in the reactor of 100ml, be heated to 150 DEG C, be incubated 13 hours；

5) after reaction terminates, it is cooled to room temperature, filters, collect, obtain zinc-oxide nano sheet material；

6) it is 7: 2: 1 by prepared zinc-oxide nano sheet material and conductive agent acetylene black and binding agent Kynoar according to mass ratio Ratio is placed in mortar, and ground and mixed is uniform, instills N-methyl pyrrolidinone solvent and is ground to pulpous state, is uniformly scratched by slurry On Copper Foil, at 60 DEG C, it is dried 12h, uses tablet machine to depress to thin slice at 5MPa pressure, obtain anode plate for lithium ionic cell.Will Gained zinc oxide negative plate, metal lithium sheet, battery case, barrier film, pad and spring leaf are placed in the glove box of full argon Row battery assembles, and obtains button CR2025 half-cell.

Zinc oxide nano sheet thickness approximates with embodiment 1 also about 85nm, XRD result, electrochemical performance data.

Embodiment 5

1) zinc acetate of 8mmol is placed in 70mL deionized water, dissolves under magnetic stirring；

2) after zinc acetate is completely dissolved, add 15.2mmol sodium citrate 15.2mmol sodium hydroxide, stir 12 hours；

3) 8mmol hexamethylenetetramine joining the solution in step 2, stirring is to dissolving；

4) proceed in the reactor of 100ml, be heated to 150 DEG C, be incubated 15 hours；

5) after reaction terminates, it is cooled to room temperature, filters, collect, obtain zinc-oxide nano sheet material；

6) it is 7: 2: 1 by prepared zinc-oxide nano sheet material and conductive agent acetylene black and binding agent Kynoar according to mass ratio Ratio is placed in mortar, and ground and mixed is uniform, instills N-methyl pyrrolidinone solvent and is ground to pulpous state, is uniformly scratched by slurry On Copper Foil, at 60 DEG C, it is dried 12h, uses tablet machine to depress to thin slice at 5MPa pressure, obtain anode plate for lithium ionic cell.Will Gained zinc oxide negative plate, metal lithium sheet, battery case, barrier film, pad and spring leaf are placed in the glove box of full argon Row battery assembles, and obtains button CR2025 half-cell.

Zinc oxide nano sheet thickness approximates with embodiment 1 also about 85nm, XRD result, electrochemical performance data.

In sum, the substantive distinguishing features of the present invention is to provide a kind of preparation side by water heat transfer nanostructured zinc oxide Method.Hydro-thermal method is relatively easy, and the nucleation of particle and the speed of growth are very fast, and the most this technology can prepare specific crystal knot Structure.The method not only technical process is simple, low cost, and avoids introducing external contaminant in each link of preparation technology. Zinc oxide nano sheet obtained by this method has good chemical property.

Unaccomplished matter of the present invention is known technology.

Claims (1)

1. can be used for a preparation method for the Zinc oxide nano sheet of lithium ion battery negative, it is characterized by comprise the steps:

(1) zinc acetate is at room temperature dissolved in deionized water as presoma；

(2) sodium citrate and sodium hydroxide are added sequentially in the solution of step one stirring 1-12 hour；

(3) addition hexamethylenetetramine, stirring and dissolving in the solution obtained the most upwards are walked；

Wherein, molar ratio of material is zinc acetate: sodium citrate: sodium hydroxide: hexamethylenetetramine=1:1.8 ~ 2.1:1.8 ~ 2.1:1；

(4) proceed to reactor, be heated to 120-160 ° of C, be incubated 10～48 hours；After reaction terminates, it is cooled to room temperature, filters, collect, obtain target material.