Spherical lanthanum-based perovskite type material and application thereof

Abstract

According to the spherical lanthanum-based perovskite type material and the application thereof, Lam (Co1-xZnx) nO3 with spherical morphology is prepared through a hydrothermal synthesis method, the Lam (Co1-xZnx) nO3 is prepared into an electrode to be applied to a capacitor and a battery, the electrochemical performance is good, the rate capability and the cycle performance are remarkably improved, overcharge / overdischarge is not likely to happen at the low temperature, and the service life of the material is prolonged. Explosion / fire is not prone to occurring at the high temperature, and the excellent electrochemical performance of a novel hybrid supercapacitor with the electrode prepared based on the novel spherical lanthanum-based perovskite type material proves that the novel electrode material has good applicability in the next generation of hybrid capacitor electrodes. In one embodiment of the invention, under the current density of 0.1 A.g <-1 > to 2A.g <-1 >, the specific capacitance and the energy density of the LaCo0. 25Zn0. 75O3 are remarkably improved, the specific capacitance reaches 8.465 F.g <-1 >, and excellent capacitance performance is shown.

Description

Technical Field

[0001] The present invention relates to the technical field of positive electrode materials, and in particular to a spherical lanthanum-based perovskite material and application thereof. Background Art

[0002] Hybrid capacitors are a type of multilayer capacitor. They are capacitors made of two or more dielectrics, usually made by stacking a dielectric with a high dielectric constant but high loss and a dielectric with a low dielectric constant but low loss. The structure can be staggered or parallel. The structure of a hybrid capacitor is similar to that of an ordinary capacitor, except that different dielectrics are applied between the electrodes and the two parts of the dielectric are connected through the free end. The "free end" is the lead of the capacitor, and its surface is generally still covered with an insulating layer to prevent breakdown near the lead.

[0003] Hybrid capacitors are usually named according to the cations that shuttle inside them, including lithium ion capacitors (LIC), sodium ion capacitors (NIC), potassium ion capacitors (KIC), zinc ion capacitors (ZIC), magnesium ion capacitors, calcium ion capacitors and aluminum ion capacitors. Hybrid capacitors can be divided into monovalent ion hybrid capacitors and multivalent ion hybrid capacitors. The high risk and environmental unfriendliness of organic electrolytes in monovalent ion hybrid capacitors restrict their development. Multivalent ion hybrid capacitors came into being, and zinc ion hybrid capacitors are one of them. Zinc is a metal with high safety, environmental friendliness, low price and good electrochemical properties.

[0004] Zinc-ion hybrid capacitor is an emerging sustainable electrochemical energy storage device that has the advantages of high energy density of aqueous zinc-ion batteries and high power density of supercapacitors. It is the direction chosen by many scientific researchers.

[0005] Among various lanthanum-based perovskite oxides (LaMnO3, LaNiO3, LaFeO3, etc.), LaCoO3 is considered to be a promising and effective material for supercapacitor electrodes because of the multiple oxidation states of cobalt atoms (Co 2+ 、Co 3+ and Co 4+ ), providing excellent electrochemical redox characteristics. In addition, lanthanum cobalt oxide has excellent electronic structure, outstanding ionic conductivity and excellent thermal stability. However, lanthanum cobalt oxide has high environmental requirements, is prone to overcharge or overdischarge at low temperatures, and may cause explosion or fire at high temperatures, which seriously hinders its widespread application. How to improve the rate performance and cycle performance of lanthanum-based perovskite materials used in batteries / capacitors has become an urgent problem to be solved. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a spherical lanthanum-based perovskite material and its application.

[0007] The technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides a spherical lanthanum-based perovskite material, and the preparation method thereof comprises the following steps:

[0009] S1, dissolving a metal salt in a solvent to obtain a mixed solution, wherein the metal salt comprises a cobalt salt and / or a zinc salt, and a lanthanum salt;

[0010] S2, adding citric acid to the mixed solution, heating and stirring until completely dissolved, hydrothermally reacting at 120-180°C for 8-12h, filtering and drying to obtain a precursor;

[0011] S3, grind the precursor into powder, and calcine at high temperature to obtain spherical La m (Co 1-x Zn x ) n O3 material, where x∈[0,1], 3m+2n=6, n>0, m>0.

[0012] Preferably, the solvent is ethanol solution.

[0013] Preferably, n:m=1:(0.5-1.5). Further, it can be preferably set to 1:1, so as to obtain LaCo 1- x Zn x O3, where x can be set to 0.25, 0.5, or 0.75.

[0014] Preferably, the molar ratio of the metal salt to citric acid is 1:(0.5-1.5).

[0015] Preferably, in step S2, the precursor drying temperature is 80-120°C.

[0016] Preferably, in step S3, the high temperature calcination temperature is 700-1100°C.

[0017] Preferably, in step S3, the high temperature calcination time is 1-3 hours.

[0018] Preferably, in step S1, the cobalt salt includes cobalt nitrate, the zinc salt includes zinc nitrate, and the lanthanum salt includes lanthanum nitrate.

[0019] The second aspect of the present invention provides an application of a spherical lanthanum-based perovskite material as described above in a battery or capacitor. The battery includes a zinc ion battery, a lithium ion battery, a sodium ion battery, a potassium ion battery, a calcium ion battery, a magnesium ion battery, etc. The capacitor includes a zinc ion capacitor, a lithium ion capacitor, a sodium ion capacitor, a potassium ion capacitor, a calcium ion capacitor, and a magnesium ion capacitor. The target battery / capacitor can be obtained by selecting the negative electrode material and the electrolyte type according to specific needs.

[0020] The third aspect of the present invention provides a use of the spherical lanthanum-based perovskite material as described above in a zinc ion battery or a zinc ion capacitor.

[0021] A fourth aspect of the present invention provides a positive electrode plate, which includes an electrolyte material, wherein the electrolyte material includes the spherical lanthanum-based perovskite material as described above.

[0022] Preferably, the method for preparing the positive electrode sheet comprises the following steps:

[0023] (1) Add NMP to a container, and then add PVDF, active substance, and Ketjen black to the container in sequence, and stir for 0.5-1.5 hours. The mass ratio of active substance: Ketjen black: PVDF is preferably 8:1:1;

[0024] (2) continuing to add the spherical lanthanum-based perovskite material into the container and stirring for 4-8 hours to obtain a slurry;

[0025] (3) The slurry is coated on a stainless steel sheet, and then vacuum dried at a temperature of 80-120° C. for 8-12 hours. After drying, the slurry is taken out and pressed into sheets.

[0026] A fifth aspect of the present invention provides a capacitor, comprising a first negative electrode shell, a spring, a gasket, a second negative electrode shell, an electrolyte, a diaphragm, a positive electrode sheet, and a positive electrode shell, wherein the positive electrode sheet comprises the positive electrode sheet as described above, and is assembled in the order of the negative electrode shell, the spring, the gasket, the negative electrode, the electrolyte, the diaphragm, the positive electrode sheet, and the positive electrode shell.

[0027] Preferably, the capacitor is a zinc ion capacitor, the negative electrode comprises a zinc sheet, and the electrolyte comprises 1-3 mol·L -1 ZnSO4.

[0028] The beneficial effects of the present invention are as follows:

[0029] First, the present invention uses a hydrothermal synthesis method to prepare La with a spherical morphology. m (Co 1-x Zn x ) nO3, which is made into electrodes for use in capacitors and batteries, has good electrochemical properties, significantly improved rate performance and cycle performance, is not prone to overcharge / overdischarge at low temperatures, and is not prone to explosion / fire at high temperatures. The excellent electrochemical properties of this new hybrid supercapacitor based on electrodes made of new spherical lanthanum-based perovskite materials confirm the good applicability of this new electrode material in the next generation of hybrid capacitor electrodes.

[0030] Furthermore, the present invention optimizes the zinc incorporation ratio and finds that appropriate zinc incorporation can increase the specific surface area of ​​the material, improve the material's wetting effect on the electrolyte, and increase the charge migration speed in the material, further enhancing its application prospects as a positive electrode material. In one embodiment of the present invention, 0.1A·g -1 -2Ag -1 At a current density of 0.25 Zn 0.75 The specific capacitance and energy density of O3 increased significantly, with the specific capacitance reaching 8.465F·g -1 , showing excellent capacitance performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0032] Figure 1 This is the preparation process of Application Example 1 of the present invention;

[0033] Figure 2 (ae) are LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 SEM-EDS images of O3 and LaZnO3;

[0034] Figure 3 (ae) are LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 EDS-mapping diagrams of O3 and LaZnO3;

[0035] Figure 4 The XRD patterns and Raman patterns of Examples 1-5 are shown below:

[0036] Figure 5 (ae) are respectively tested at different scanning rates for LaCoO3 and LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 CV curves of O3 and LaZnO3 electrodes;

[0037] Figure 6 For LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Specific capacitance curves of O3 and LaZnO3;

[0038] Figure 7 (a, b) are respectively at 200mV s -1 At a scan rate of 5 mV s -1 At the scanning rate, LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Cyclic voltammetry curves of O3 and LaZnO3;

[0039] Figure 8 (ae) are LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 CP curves of O3 and LaZnO3;

[0040] Fig. 9 For LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Specific capacitance curves of O3 and LaZnO3;

[0041] Fig.10(ab) are respectively at 5A·g -1 At a current density of 0.1 A·g -1 At the current density of LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 CP curves of five materials including O3 and LaZnO3;

[0042] Fig.11 For LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 EIS curves of five materials including O3 and LaZnO3;

[0043] Fig.12 For LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Lagon curves of five materials including O3 and LaZnO3;

[0044] Fig.13 (ab) are LaCo 0.25 Zn 0.75 Capacitance distribution diagram and B value diagram of O3 material;

[0045] Fig.14 For LaCo 0.25 Zn 0.75 Cycle diagram of O3 material. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0047] Example 1

[0048] (1) Co(NO3)2·6H2O and La(NO3)3·6H2O in a molar ratio of 1:1 are dissolved in ethanol to obtain a mixed solution, and then citric acid is added dropwise to the mixed solution, and the molar ratio of citric acid to La(NO3)3·6H2O is 2:1;

[0049] (2) under strong magnetic stirring, the above solution was stirred and dissolved to form a purple translucent solution, and the obtained purple translucent solution was placed in a polytetrafluoroethylene liner, and then placed in a stainless steel reactor for hydrothermal reaction at 120° C. for 10 h;

[0050] (3) filtering and washing the hydrothermal reaction product, drying it in air at 100° C. for 24 hours, and then grinding it with a mortar to obtain a powder;

[0051] (4) The above powder was heated to 900°C in a tube furnace at a heating rate of 5°C / min, maintained for 2 hours, and then cooled to obtain LaCoO3.

[0052] Example 2

[0053] The difference between this embodiment and embodiment 1 is that in step (1), Co(NO3)2·6H2O, La(NO3)3·6H2O, and Zn(NO3)2·6H2O in a molar ratio of 0.75:1:0.25 are dissolved in ethanol to obtain a mixed solution, and LaCo is finally obtained. 0.75 Zn 0.25 O3.

[0054] Example 3

[0055] The difference between this embodiment and embodiment 1 is that in step (1), Co(NO3)2·6H2O, La(NO3)3·6H2O, and Zn(NO3)2·6H2O in a molar ratio of 0.5:1:0.5 are dissolved in ethanol to obtain a mixed solution, and LaCo is finally obtained. 0.5 Zn 0.5 O3.

[0056] Example 4

[0057] The difference between this embodiment and embodiment 1 is that in step (1), Co(NO3)2·6H2O, La(NO3)3·6H2O, and Zn(NO3)2·6H2O in a molar ratio of 0.25:1:0.75 are dissolved in ethanol to obtain a mixed solution, and LaCo is finally obtained. 0.25 Zn 0.75 O3.

[0058] Example 5

[0059] The only difference between this embodiment and embodiment 1 is that in step (1), La(NO3)3·6H2O and Zn(NO3)2·6H2O in a molar ratio of 1:1 are dissolved in ethanol to obtain a mixed solution, and finally LaZnO3 is prepared.

[0060] Application Example 1

[0061] like Figure 1 The steps are as follows:

[0062] (1) Add 1 mL of NMP to a small mixing bottle, and add 0.01 g of PVDF to a discharge bottle in the order of PVDF, active substance, and Ketjen black in a mass ratio of 8:1:1, and stir for 1 h.

[0063] (2) Then add 0.08g of LaCo 1-x Zn x O3 (x = 0, 0.25, 0.5, 0.75, 1) was stirred for 6 h, and the finished slurry products were named according to the abbreviations of the products (x = 0, 0.25, 0.5, 0.75, 1).

[0064] (3) Carefully apply the slurry onto a stainless steel sheet using a four-sided preparation device, then place it in a vacuum drying oven and set the temperature to 100°C for drying for 10 hours. After drying, take it out and press it into sheets.

[0065] Application Example 2

[0066] According to the negative electrode shell, shrapnel, gasket, negative electrode (zinc sheet), electrolyte (2mol L -1 The zinc ion hybrid capacitor is assembled in the order of ZnSO4), thick diaphragm, positive electrode sheet, and positive electrode shell, and then packaged with a battery sealing machine. The positive electrode sheet is prepared by the method of Application Example 1.

[0067] Structural characterization and analysis

[0068] LaCo prepared in Examples 1-5 1-x Zn x O3 materials were structurally characterized, such as Figure 2 (ae) show LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 SEM-EDS images of O3 and LaZnO3 materials. Figure 2 (a) It can be clearly observed that LaCoO3 presents a spherical morphology, with an uneven surface and many small agglomerates. This structure is conducive to the full infiltration of the electrolyte;

[0069] (2) Figure 2 (b) LaCo 0.75 Zn 0.25O3 has a spherical shape with a concave shape in the middle, resembling a loquat. There are many small particles dispersed evenly on the spherical surface, which is similar to the morphology of the lanthanum cobalt oxide matrix;

[0070] (3) Figure 2 (c) LaCo 0.5 Zn 0.5 Scanning electron microscope image of O3 material shows that the material is spherical and has obvious cracks, which is conducive to achieving high electronic conductivity;

[0071] (4) Figure 2 (d) LaCo 0.25 Zn 0.75 From the scanning electron microscope image of the O3 material, it can be observed that the material is spherical, which is beneficial to shortening the diffusion path of zinc ions.

[0072] (5) can be Figure 2 (e) shows that LaZnO3 powder is composed of small blocks with a relatively rough surface, which can effectively increase the surface area.

[0073] Figure 3 (ae) are LaCoO3 and LaCo prepared in Examples 1-5 respectively. 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 O3, LaZnO3 and EDS-mapping diagrams of five materials. The EDS-mapping diagram shows the distribution of various elements in the materials. 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 The distribution of various elements in O3 is similar; the distribution of various elements in LaZnO3 is quite different from that in the other four materials. Figure 3 In (bd), the Zn element is seen, indicating that Zn has been successfully doped into the lanthanum cobalt oxide.

[0074] Figure 4 In the paper, LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75The XRD and Raman spectra of five materials, O3, LaZnO3, and LaZnO3, show that the peaks at 2θ=38.992° and 54.336° correspond to the (100) and (102) lattice planes of the Zn hexagonal system (JCPDS card 04-0831), respectively, while the peaks at 2θ=26.002°, 29.817°, 39.563°, 45.862°, 52.1°, and 56.515° correspond to the (210), (031), (301), (241), (401), and (303) lattice planes of the CoLa3 cubic system (JCPDS card 27-1116), respectively.

[0075] Electrochemical performance analysis

[0076] 1. Cyclic voltammetry curve

[0077] like Figure 5 (ae) are LaCoO3 and LaCo at different scanning rates. 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Cyclic voltammetry curves of O3 and LaZnO3.

[0078] (1) When the voltage window is 0.2-1.7V, LaCo 0.25 Zn 0.75 O3 can play a better performance.

[0079] (2) By observing the five CV curves, LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 O3, LaZnO3 and other five materials showed no obvious redox peaks at different scanning rates, and the CV curves of capacitors prepared from the five materials were close to rectangles.

[0080] (3) The embedding / de-embedding of metal ions at the electrode / electrolyte interface and the ion diffusion rate in the electrode can be seen from the CV curve. -1 , 10mV s -1 , 20mV s -1 , 50mV s -1 , 100mV s -1 , 200mV s -1 , 500mV s -1) under CV curve. It can be seen from the figure that the CV curve is stable with the increase of scanning rate, showing a small polarization rate and good rate performance.

[0081] Figure 6 For LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Specific capacitance curves of five materials including O3, LaZnO3.

[0082] (1) Compare the specific capacitance of the five materials in the figure below. LaCo 0.25 Zn 0.75 The CV specific capacitance curve of O3 is higher than that of the other four materials, indicating that LaCo 0.25 Zn 0.75 O3 has a higher specific capacity. This indicates that the partial substitution of zinc for cobalt ions has a great influence on improving the electrochemical performance by generating oxygen vacancies.

[0083] (2) By analyzing the specific capacitance performance of the figure below, as the scanning speed increases, LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.25 Zn 0.75 O3 and other three materials have a larger reduction in specific capacitance. 0.5 Zn 0.5 O3 and LaZnO3 have a smaller decrease in specific capacitance. This indicates that the more zinc content, the better. 0.25 Zn 0.75 The specific capacitance of O3 is generally the best, probably because the multivalent state of cobalt atoms can provide more redox potential, and the proper incorporation of zinc can make the electrolyte infiltration more complete.

[0084] Figure 7 (a) and (b) are respectively the -1 At a scan rate of 200 mV s -1 At the scanning rate, LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Cyclic voltammetry curves of five materials including O3, LaZnO3.

[0085] It can be seen from the figure that: (1) At low scanning rates, there are some redox peaks, indicating that the capacitor may have pseudocapacitance; at high scanning rates, the shapes of the CV curves of the five materials tend to be rectangular, which may be because the scanning rate is too fast, making the surface of the material insufficiently utilized, and the electrons in certain positions inside have no time to diffuse and transport.

[0086] (2) At low scanning rates, LaCo 0.25 Zn 0.75 The CV curve area of ​​O3 is the largest compared with the other four materials; at high scan rates, LaCo 0.25 Zn 0.75 The CV curve area of ​​O3 is the largest compared with the other four materials, and its specific capacity is also the highest.

[0087] 2. Charge and discharge curve

[0088] Figure 8 (ae) are LaCoO3 and LaCo at different scanning rates. 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Constant current charge and discharge curves of capacitors assembled from five materials, including O3, LaZnO3, and others, at different current densities.

[0089] From the figure we can see that:

[0090] (1) LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 The CP curves of O3 and LaZnO3 are linear at lower current density, and no pseudocapacitance is generated. At higher current density, the discharge time is shorter than the charging time, and the discharge efficiency is low.

[0091] (2) When LaCoO3 is the positive electrode, the current density is 0.1A g -1 When the specific capacitance is 4.88Fg -1 ; For LaCo 0.75 Zn 0.25 When O3 is the positive electrode, the current density is 0.1A g -1 When the specific capacitance is 6.27F g -1 ; For LaCo 0.5 Zn 0.5 When O3 is the positive electrode, the current density is 0.1A g -1 When the specific capacitance is 1.60F g-1 ; For LaCo 0.25 Zn 0.75 When O3 is the positive electrode, the current density is 0.1A g -1 When the specific capacitance is 7.90F g -1 ; When LaZnO3 is the positive electrode, when the current density is 0.1A g -1 When the specific capacitance is 1.11Fg -1 And with the increase of current density, the specific capacitance of both shows a decreasing trend.

[0092] (3) By comparing the specific capacitance of the five materials, it can be seen that at the above current density, LaCo 0.25 Zn 0.75 The specific capacitance of O3 is greater than that of the other four.

[0093] Fig. 9 LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Dotted line graph of the specific capacitance calculated from the discharge time of the CP curves of five materials including O3, LaZnO3.

[0094] It can be seen from the figure that: (1) at 0.1A g -1 Under the condition of 0.25 Zn 0.75 The specific capacity of O3 is the largest among the five composite materials, and at 0.5 A g -1 Under the conditions, it can be seen that LaCo 0.25 Zn 0.75 The specific capacity of O3 is larger than that of the other five materials.

[0095] (2) By comparing the specific capacitance of the five materials, it can be seen that at 0.1A g -1 At the current density of , the specific capacitances are LaCo 0.25 Zn 0.75 O3、LaCo 0.75 Zn 0.25 O3、LaCoO3、LaCo 0.5 Zn 0.5 O3, LaZnO3. But in 5A g -1 At the current density of , the specific capacitances are LaCo 0.75 Zn 0.25 O3、LaCoO3、LaCo 0.25 Zn 0.75 O3、LaCo0.5 Zn 0.5 O3, LaZnO3.

[0096] Fig.10 (a) and (b) are respectively -1 At a current density of 5A g -1 At the current density of 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 CP curves of five materials including O3, LaZnO3.

[0097] It can be seen from the figure that: (1) At a current density of 0.1A g -1 When the current density is 5A g -1 When LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 O3 bends severely to the right.

[0098] (2) Under the above two current densities, the charge and discharge efficiency of the five materials at the larger current density is greater than that at the smaller current density.

[0099] 3. Electrochemical impedance spectroscopy curve

[0100] Fig.11 For LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75 Electrochemical impedance spectra of five materials including O3, LaZnO3.

[0101] It can be seen from the figure that: (1) In the high-frequency region, the starting point represents the resistance generated by the material itself, that is, the ohmic impedance. The five materials are not much different, which means that the ohmic impedance of the five materials is not much different.

[0102] (2) In the medium and high frequency region, the semicircle represents the charge transfer process on the surface of the composite electrode, and a smaller semicircle shows a smaller charge transfer resistance. 0.25 Zn 0.75 O3 and LaZnO3 have smaller charge transfer impedance.

[0103] (3) In the low frequency region, the magnitude of the ion migration impedance can be intuitively seen from the slope of the straight line. 0.5 Zn 0.5 The slopes of O3 and LaZnO3 are relatively large, indicating that the ion migration impedance resistance of these four materials is small, and the faster the ion diffusion speed, the better the conductivity. 0.75 Zn 0.25 O3 is relatively gentle.

[0104] Energy density and power density

[0105] Table 1-5 shows the energy density and power density of five materials:

[0106] Table 1 Energy density and power density of LaCoO3 electrode

[0107]

[0108]

[0109] Table 2 LaCo 0.75 Zn 0.25 Energy density and power density of O3 electrode

[0110]

[0111] Table 3 LaCo 0.5 Zn 0.5 Energy density and power density of O3 electrode

[0112]

[0113]

[0114] Table 4 LaCo 0.25 Zn 0.75 Energy density and power density of O3 electrode

[0115]

[0116] Table 5 Energy density and power density of LaZnO3 electrode

[0117]

[0118] From Table 1-5, LaCoO3, LaCo 0.75 Zn 0.25 O3、LaCo 0.5 Zn 0.5 O3、LaCo 0.25 Zn 0.75The energy density and power density of five materials including O3, LaZnO3 and Fig.13 From the Lagon curve, we can know that:

[0119] (1) When a capacitor is composed of five materials as electrodes, as the current density increases, the specific capacitance of the two gradually decreases, the energy density gradually decreases, and the power density gradually increases.

[0120] (2) By observing the table of the five materials and comparing the specific capacity, energy density and power density of the five materials, it can be found that at low current density, LaCo 0.25 Zn 0.75 O3 has the highest energy density.

[0121] (3) Through the Lagon curve, we can compare the performance of the five composite materials, LaCo 0.25 Zn 0.75 O3 shows a more gradual decline, showing an impressive energy / power ratio, which is better than that of LaCoO3.

[0122] Fig.13 For LaCo 0.25 Zn 0.75 O3 material at 5mV s -1 , 10mV s -1 , 20mV s -1 , 50mV s -1 , 100mV s -1 , 200mV s -1 , 500mV s -1 Capacitance distribution diagram and B value diagram under scanning rate.

[0123] (1) LaCo 0.25 Zn 0.75 O3 at a scan rate of 5 mV s -1 and 10mV s -1 When the capacitance is mainly controlled by diffusion kinetics, at 20 mV s -1 , 50mV s -1 , 100mV s -1 , 200mV s -1 , 500mV s -1 When , its capacitance is mainly controlled by capacitance dynamics.

[0124] (2) By taking the logarithm of the scan rate and the peak current, the slope b value can be obtained. After processing, it is found that LaCo 0.25 Zn 0.75 The b value of O3 is 0.8616.

[0125] Fig.14 For LaCo0.25 Zn 0.75 O3 material at 5mV s -1 , 10mV s -1 , 20mV s -1 , 50mV s -1 , 100mV s -1 , 200mV s -1 , 500mV s -1 Cycle diagram under scanning rate. Through the cycle diagram, it can be obtained that LaCo 0.25 Zn 0.75 During the 1000 cycles of O3, the capacity retention rate remained basically unchanged, indicating that the performance of the zinc ion hybrid capacitor was stable.

[0126] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A spherical lanthanum-based perovskite material, characterized in that: The preparation method thereof comprises the following steps: S1, dissolving a metal salt in a solvent to obtain a mixed solution, wherein the metal salt comprises a cobalt salt and / or a zinc salt, and a lanthanum salt; S2, adding citric acid dropwise to the mixed solution to dissolve, hydrothermally reacting at 120-180°C for 8-12h, filtering and drying to obtain a precursor; S3, grind the precursor into powder, and calcine at high temperature to obtain spherical La m (Co 1-x Zn x ) n O3 material, where x∈[0,1], 3m+2n=6, n>0, m>0.

2. A spherical lanthanum-based perovskite material according to claim 1, characterized in that: The n:m=1:(0.5-1.5).

3. The spherical lanthanum-based perovskite material according to claim 1, characterized in that: The molar ratio of the metal salt to the citric acid is 1:(0.5-1.5).

4. The spherical lanthanum-based perovskite material according to claim 1, characterized in that: In step S3, the high temperature calcination temperature is 700-1100°C.

5. The spherical lanthanum-based perovskite material according to claim 1, characterized in that: In step S3, the high temperature calcination time is 1-3 hours.

6. The spherical lanthanum-based perovskite material according to claim 1, characterized in that: In step S1, the cobalt salt includes cobalt nitrate, the zinc salt includes zinc nitrate, and the lanthanum salt includes lanthanum nitrate.

7. Use of a spherical lanthanum-based perovskite material as described in any one of claims 1 to 6 in a battery or a capacitor.

8. Use of a spherical lanthanum-based perovskite material as claimed in any one of claims 1 to 6 in a zinc ion battery or a zinc ion capacitor.

9. A positive electrode plate, characterized in that: It comprises an electrolyte material, wherein the electrolyte material comprises the spherical lanthanum-based perovskite material according to any one of claims 1 to 6.

10. A capacitor, characterized in that: It includes a negative electrode shell, a spring, a gasket, a negative electrode, an electrolyte, a diaphragm, a positive electrode plate, and a positive electrode shell, wherein the positive electrode plate includes the positive electrode plate according to claim 9.

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