CN112320845A

CN112320845A - Perovskite structure vanadate-based battery negative electrode active material

Info

Publication number: CN112320845A
Application number: CN202011206058.3A
Authority: CN
Inventors: 刘颖; 李小磊; 林紫锋; 杜义波; 杨晓娇; 欧阳林峰
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2020-11-02
Filing date: 2020-11-02
Publication date: 2021-02-05
Anticipated expiration: 2040-11-02
Also published as: CN112320845B

Abstract

The invention discloses a negative electrode active material of a vanadate-based battery with a perovskite structure, wherein the negative electrode material is alkaline earth vanadate AVO with the perovskite structure₃(A ═ Ca, Sr, Ba), the alkaline earth vanadate AVO₃Comprising calcium vanadate CaVO₃Strontium vanadate SrVO₃Barium vanadate BaVO₃One or more of; the alkaline earth vanadate AVO₃Comprising a non-stoichiometric vanadate A having a non-stoichiometric ratio x of 0.3 to 1.2_xVO₃(ii) a The invention has the beneficial effects that: vanadate AVO with perovskite structure₃(A ═ Ca, Sr, Ba) as a battery material active material not only has advantages of high capacity, high rate, long cycle stability, etc., but also improves the pseudo-capacitance capacity contribution by controlling the vacancy concentration by controlling the addition amount of the alkaline earth metal AHigh electrochemical performance; the vanadate with the perovskite structure has low and safe working voltage, and ensures the safety during charging and discharging.

Description

Perovskite structure vanadate-based battery negative electrode active material

Technical Field

The invention relates to the field of battery materials, in particular to a vanadate-based battery negative electrode active material with a perovskite structure.

Background

The negative electrode material is one of the main factors affecting the battery performance. The negative electrode material of the battery is composed of an active material, a conductive agent and a binder, wherein the active material determines the intercalation and deintercalation capacity of battery ions and is also a decisive factor for determining energy density. The current commercial battery cathode is a graphite cathode (380mAh/g) due to the lower lithium intercalation potential (-0.1V vs Li)⁺and/Li), lithium dendrite is easily generated when the lithium battery is rapidly charged and discharged and overcharged as a power battery, thereby causing poor rate performance and serious safety problems. The charge-discharge voltage of the lithium titanate is higher (1.5V vs Li)⁺Li), but its excessively high potential and extremely low capacity (-180 mAh/g) severely limit its energy density. In addition, the problem of low conductivity of lithium titanate also limits that more conductive agents (5-8 wt%) need to be added during application of lithium titanate, and excessive addition of the conductive agents can reduce the mass and volume energy density, reduce the mechanical properties of the pole piece and improve the preparation cost of the pole piece.

The rapid development of the current power battery needs the battery to have the characteristics of high capacity, high multiplying power, long cycle stability, safety and the like so as to meet the requirement of high mileage; however, the electrochemical characteristics and related studies of the existing metal vanadate with perovskite structure as the battery negative electrode material are only reported at present.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a negative electrode active material of a vanadate-based battery with a perovskite structure, so as to at least achieve the aims of high electrochemical performance, safety and high efficiency.

The purpose of the invention is realized by the following technical scheme:

the negative electrode active material of the vanadate-based battery with the perovskite structure is alkaline earth vanadate AVO with the perovskite structure₃(A ═ Ca, Sr, Ba), the alkaline earth vanadate AVO₃Comprising calcium vanadate CaVO₃Strontium vanadate SrVO₃Barium vanadate BaVO₃One or more of; wherein the calcium vanadate CaVO₃Strontium vanadate SrVO₃And/or barium vanadate BaVO₃Mixing the above materials.

Preferably, for further achieving the purpose of safety and high efficiency, the perovskite-structured alkaline earth vanadate AVO₃(A ═ Ca, Sr, Ba) includes a non-stoichiometric perovskite-structured alkaline earth vanadate A having a non-stoichiometric ratio of x between the alkaline earth metal source A and the vanadium source V_xVO₃(a ═ Ca, Sr, Ba); the value range of the ratio x of the non-stoichiometric number is 0.3-1.2; by limiting alkaline earth vanadate A_xVO₃Taking value in a non-stoichiometric ratio, and utilizing the fact that the vacancy of the alkaline earth metal source A in the perovskite structure has larger tolerance, the vacancy of the metal source A can be allowed to exist in large quantity, and when the ratio of the metal source A to the vanadium source V is within 0.3-1.2, the perovskite structure can exist stably. The perovskite vanadate with the special vacancy structure can provide more pseudo capacitors, and meanwhile, the structural stability is kept, so that the obtained electrode can stably work, the situation similar to lithium dendrite is avoided, and the safety and the high efficiency of the battery work are realized.

Preferably, for further achieving the purpose of safety and high efficiency, the perovskite-structured alkaline earth vanadate AVO₃(a ═ Ca, Sr, Ba) includes crystalline, amorphous, and/or mixed crystalline and amorphous structures; the phase can be prepared by a conventional method of a solid phase method, a sol method and/or a hydrothermal method, and the non-crystal and amorphous and crystal mixed structure can be prepared by a method of rapid heating and cooling, so that the processes of nucleation and grain growth are controlled, and the perovskite structure alkaline earth vanadate AVO with a stable structure is obtained₃Therefore, the prepared electrode can work stably, and the safety and high efficiency of the battery work are realized.

Preferably, for the purpose of further achieving high electrochemical performance, the perovskite-structured alkaline earth vanadate AVO₃(A ═ Ca, Sr, Ba) is alkaline earth vanadate AVO with carbon-containing perovskite structure₃The composite of (a); the mass fraction value range of C is 0-20 wt%; due to the removal of impurity phases from the selected raw materials or from the preparation stageTherefore, carbon impurities are bound to exist, the mass fraction of the carbon impurities is limited, the working voltage can be reduced, the conductivity in the material can be increased, and high electrochemical performance can be guaranteed.

Preferably, for the purpose of further achieving high electrochemical performance, the alkaline earth vanadate A having a perovskite structure_xVO₃(A ═ Ca, Sr, Ba), contains V₂O₃、VO₂And/or VO_yAnd include Sr₃V₂O₈And/or Sr₆V₆O₁₉Oxidation phase impurities of (a); the VO_yThe value range of y in the vanadium oxide of (1)<y<1.5; by limiting the inclusion species of the impurities and the composition range of the vanadium oxide, the influence of the vanadium oxide and the oxidation phase impurities on the electrical property of the electrode material is reduced, and VO is limited_yThe value range of y in the vanadium oxide limits tiny vanadium oxide components, thereby obtaining the perovskite alkaline earth vanadate AVO close to single phase₃(a ═ Ca, Sr, Ba), the purpose of high electrochemical performance is indirectly achieved.

Preferably, for the purpose of further achieving high electrochemical performance, the alkaline earth vanadate AVO with the perovskite structure₃Use of (a ═ Ca, Sr, Ba) as a battery negative electrode active material; the battery cathode material comprises alkaline earth vanadate AVO (AVO)₃: conductive agent: 70-99% of binder: 20-0: 10-1; by defining the composition of each substance in the battery anode material, the alkaline earth vanadate AVO is utilized₃The conductive agent and the binder are matched to form a stable and efficient electrode material, so that the aim of high electrochemical performance is fulfilled.

The invention has the beneficial effects that: vanadate AVO via perovskite structures₃As an active material of a battery material, (a ═ Ca, Sr, Ba) has not only advantages such as high capacity, high rate, long cycle stability, but also can further improve the contribution of pseudocapacitance capacity by controlling the concentration of alkaline earth metal a vacancies in the perovskite structure by controlling the stoichiometric ratio x of alkaline earth metal a to metal V, thereby improving electrochemical performance. Perovskite structureThe vanadate also has low and safe working voltage (1V vs Li/Li) when being used as a novel battery cathode active material⁺) The lithium secondary battery can ensure safety during rapid charging and discharging and prevent the formation of lithium dendrites. The high-conductivity characteristic enables the electrode plate to obtain a high-surface-appearance electrode plate without adding a conductive agent, and meanwhile, the electrode plate has high volume energy density and great commercialization potential. In addition, the vanadate has low cost, is green and environment-friendly, and is suitable for industrial popularization.

Drawings

FIG. 1 shows strontium vanadate SrVO₃Schematic structural diagram of (a);

FIG. 2 shows calcium vanadate CaVO₃Schematic structural diagram of (a);

FIG. 3 shows BaVO as barium vanadate₃Schematic structural diagram of (a);

FIG. 4 shows strontium vanadate SrVO of example 1₃An X-ray diffraction spectrum (XRD pattern) of the material;

FIG. 5 shows strontium vanadate SrVO of example 1₃Scanning electron micrographs (SEM images) of the material;

FIG. 6 is SrVO of example 1₃A voltage capacity diagram of a lithium ion battery using 20 wt% of conductive agent in an electrode material within a potential range of 0.01-3V;

FIG. 7 shows strontium vanadate SrVO of example 1₃A multiplying power performance diagram of the lithium ion battery without using a conductive agent in a potential range of 0.01-3V for the electrode material;

FIG. 8 shows strontium vanadate SrVO of example 1₃A cycle performance diagram of the lithium ion battery with the electrode material in a potential range of 0.01-3V;

FIG. 9 shows strontium vanadate SrVO of example 1₃The high-area capacity diagram of the lithium ion battery with the electrode material in a potential range of 0.01-3V;

FIG. 10 shows calcium vanadate CaVO of example 2₃An X-ray diffraction spectrum of the material;

FIG. 11 shows calcium vanadate CaVO of example 2₃Scanning electron micrographs of the material;

FIG. 12 shows calcium vanadate CaVO of example 2₃A voltage capacity diagram of the lithium ion battery with the electrode material in a potential range of 0.01-3V;

FIG. 13 shows BaVO being barium vanadate of example 3₃An X-ray diffraction spectrum of the material;

FIG. 14 shows BaVO, a barium vanadate of example 3₃Scanning electron micrographs of the material;

FIG. 15 shows BaVO, a barium vanadate of example 3₃A voltage capacity diagram of the lithium ion battery with the electrode material in a potential range of 0.01-3V;

FIG. 16 is CaVO of example 4₃、SrVO₃、BaVO₃X-ray diffraction spectra of the blended materials;

FIG. 17 shows CaVO of example 4₃、SrVO₃、BaVO₃A voltage capacity diagram of the lithium ion battery with the blended electrode material in a potential range of 0.01-3V;

FIG. 18 is a non-stoichiometric strontium vanadate Sr of example 5_0.3VO₃An X-ray diffraction spectrum of the material;

FIG. 19 is a non-stoichiometric strontium vanadate Sr of example 5_0.3VO₃Scanning electron micrographs of the material;

FIG. 20 shows the non-stoichiometric strontium vanadate Sr of example 5_0.3VO₃A voltage capacity diagram of the lithium ion battery with the electrode material in a potential range of 0.01-3V;

FIG. 21 is strontium vanadate Sr in example 6_1.2VO₃+ impurity Sr₃V₂O₈X-ray diffraction spectra of phase materials;

FIG. 22 shows strontium vanadate Sr in example 6_1.2VO₃+ impurity Sr₃V₂O₈Scanning electron micrographs of the phase material;

FIG. 23 shows strontium vanadate Sr in example 6_1.2VO₃+ impurity Sr₃V₂O₈A voltage capacity diagram of the lithium ion battery with the phase electrode material in a potential range of 0.01-3V;

FIG. 24 is strontium vanadate Sr of example 7_0.3VO₃+ impurity V₂O₃X-ray diffraction spectra of phase materials;

FIG. 25 shows strontium vanadate Sr in example 7_0.3VO₃+ impurity V₂O₃Scanning electron micrographs of the phase material;

FIG. 26 is strontium vanadate Sr in example 8_0.3VO₃+ impurity V₂O₃A voltage capacity diagram of the lithium ion battery with the phase electrode material in a potential range of 0.01-3V;

FIG. 27 is a non-stoichiometric strontium vanadate Sr of example 8_0.3VO₃X-ray diffraction spectra of amorphous materials;

FIG. 28 is the non-stoichiometric strontium vanadate Sr of example 8_0.3VO₃Scanning electron micrographs of amorphous material;

FIG. 29 is a non-stoichiometric strontium vanadate Sr of example 8_0.3VO₃A voltage capacity diagram of the lithium ion battery with the amorphous electrode material in a potential range of 0.01-3V;

FIG. 30 is a non-stoichiometric strontium vanadate Sr of example 9_0.3VO₃X-ray diffraction spectra of amorphous and crystalline composite structural materials;

FIG. 31 is a non-stoichiometric strontium vanadate Sr of example 9_0.3VO₃Scanning electron micrographs of amorphous and crystalline composite structural materials;

FIG. 32 shows the non-stoichiometric strontium vanadate Sr of example 9_0.3VO₃And the voltage capacity diagram of the lithium ion battery with the amorphous and crystalline composite structure electrode material in a potential range of 0.01-3V.

Detailed Description

The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following.

Example 1

Alkaline earth strontium vanadate SrVO adopting perovskite structure as shown in figure 1₃The crystal material is of a standard cubic perovskite structure. The XRD pattern shown in figure 4 shows that the diffraction peak of the strontium vanadate is similar to that of standard strontium vanadate SrVO₃The contrast is consistent, and no other impurity phase exists; as shown in fig. 5, the SEM image shows that the structure is foam-like, and is composed of nano-sheets and nano-particles connected with each other; analysis of the carbon content indicated that no residual carbon was present. The specific parameters are shown in Table 1Shown in the figure.

TABLE 1 strontium vanadate SrVO₃Table of parameter situation

The strontium vanadate SrVO₃Electrochemical performance test as lithium battery: strontium vanadate SrVO₃Conductive agent super P and binder PVDF according to 70: 20: 10, coating the mixture into an electrode, taking a metal lithium sheet as a counter electrode, testing by adopting a button cell, and testing the performance of the battery under the current density of 0.05A/g by using constant current charge and discharge, wherein the reversible specific capacity can reach 400mAh/g as shown in a) and b) of fig. 6;

strontium vanadate SrVO₃Conductive agent super P and binder PVDF according to 99: 0: the specific capacity of 380mAh/g can be still maintained under the current density of 0.05A/g, and as shown in a) and b) of fig. 7, the specific capacity can still be stabilized at 140mAh/g when the current density is increased from 0.05A/g to 10A/g. And when the current density returns to 0.1A/g again, the specific capacity is increased to 330mAh/g without attenuation, which indicates that SrVO₃The high conductivity of the material can effectively transmit electrons. When in use, a proper amount of conductive agent can be added according to the requirement, and the excellent multiplying power and stability can be ensured.

Meanwhile, as shown in FIG. 8, the prepared electrode material has excellent long cycle stability in a potential range of 0.01-3V, and capacity does not decay after 3000 times of cycle under the current density of 1A/g.

As shown in FIG. 9, the prepared SrVO₃The specific capacity of the electrode material in the area within the potential range of 0.01-3V is increased along with the increase of the unit area loading capacity, and is 15.81g/cm²Can reach 6mAh/cm under the surface loading capacity²The high surface loading capacity of the composite material is far higher than that of the actual commercial 2-3 mAh/cm²Further proves SrVO₃Height of electrode materialThe performances of conductivity, high specific capacity and the like are suitable for the field of commercial electrode preparation.

Example 2

Alkaline earth calcium vanadate CaVO adopting perovskite structure as shown in FIG. 2₃The specific parameters of the crystal material are shown in Table 2. Since the Ca ion diameter is smaller than that of Sr, the perovskite structure is pseudo-cubic. The XRD pattern shown in FIG. 10 shows diffraction peaks corresponding to standard calcium vanadate CaVO₃The contrast is consistent, and no other impurity phase exists; as shown in fig. 11, the SEM image shows that the structure is a sheet-like nanomaterial;

TABLE 2 calcium vanadate CaVO₃Table of parameter situation

The calcium vanadate CaVO is added₃Electrochemical performance test as lithium battery: calcium vanadate CaVO₃Conductive agent super P and binder PVDF according to 80: 10: 10 to form an electrode, and the rest is the same as the embodiment 1, as shown in a) and b) of figure 12, the reversible specific capacity can reach 420 mAh/g;

in comparison with example 1, it can be seen that calcium vanadate CaVO₃The specific capacity of the electrode material is slightly higher than that of strontium vanadate SrVO₃May be due to its larger unit cell volume or the smaller ionic radius of Ca for lithium ion transport. In addition, the charge and discharge curves of the two are the same, because the two are perovskite structures, the storage sites of lithium ions in the perovskite structures are the same, and the transmission routes are also the same, so that the specific capacities and the multiplying powers of the two have similar characteristics.

Example 3

Alkaline earth barium vanadate BaVO adopting perovskite structure as shown in FIG. 3₃The crystal material and the specific data thereof are shown in Table 3. Barium vanadate has a standard perovskite structure, and the volume of a unit cell of the barium vanadate is slightly larger than that of strontium vanadate.

The XRD pattern shown in FIG. 13 shows diffraction peaks corresponding to standard calcium vanadate BaVO₃The contrast is consistent, and no other impurity phase exists; as shown in FIG. 14, the SEM image thereof showsThe structure of the nano-particles is micro-particles, and compared with the nano-particles in example 1 and example 2, the nano-particles have obvious morphology. BaVO₃The perovskite structure preparation usually requires high pressure conditions, and nano-flaky particles are difficult to obtain, so that the powder used is micron particles.

Table 2 calcium vanadate BaVO₃Table of parameter situation

Mixing the barium vanadate BaVO₃Electrochemical performance test as lithium battery: calcium vanadate and barium vanadate BaVO₃Conductive agent super P and binder PVDF according to 80: 10: 10 to form an electrode, and the rest is the same as the embodiment 1, as shown in figure 15, the reversible specific capacity can reach 280 mAh/g;

compared with the strontium vanadate SrVO in example 1₃And calcium vanadate CaVO of example 2₃As can be seen, barium vanadate BaVO₃The capacity of the electrode material (2) was lower because the active sites were less in the micro-particles than in the nano-particles, and thus the specific capacity was lower, but it can be seen that even the barium vanadate BaVO was in the micro-state₃The higher multiplying power can be kept along with the increase of the current, which shows that the alkaline earth metal vanadate with the perovskite structure has the characteristic of high multiplying power.

Example 4

The strontium vanadate SrVO₃Calcium vanadate CaVO₃And barium vanadate BaVO₃According to the mass part of 30: 30: 40, with an XRD pattern as shown in fig. 16, with diffraction peaks consistent with the standard vanadate control for each blend material, with no other impurity phases.

The blended material is used for electrochemical performance test of a lithium battery: mixing the following materials: conductive agent super P and binder PVDF according to 98:0:2 to form an electrode, and the reversible specific capacity of the electrode is 370mAh/g in the same steps as in example 1, such as a) and b) in FIG. 17.

Example 5

Using a non-stoichiometric ratio x of 0.3Alkaline earth strontium vanadate Sr of perovskite structure_0.3VO₃The crystal material has XRD pattern shown in FIG. 18, and diffraction peak thereof is similar to that of standard strontium vanadate SrVO₃The contrast is consistent, and no other impurity phase exists; as shown in fig. 19, the SEM image shows that the structure is foam-like, and is composed of nano-sheets and nano-particles connected to each other.

The non-stoichiometric strontium vanadate Sr is adopted_0.3VO₃Electrochemical performance test as lithium battery: strontium vanadate Sr with non-stoichiometric ratio_0.3VO₃The conductive agent super P and the binder PVDF are coated into an electrode according to the proportion of 98:0:2, the carbon content C of the electrode is ensured to be 0 wt%, a metal lithium sheet is used as a counter electrode, a button cell is adopted for testing, the performance of the battery is tested under the current density of 0.05A/g by using constant current charge and discharge, and as shown in a) and b) of figure 20, the reversible specific capacity can reach 440 mAh/g;

strontium vanadate SrVO compared to the standard stoichiometric ratio in example 1₃Nonstoichiometric Sr containing a large number of strontium Sr vacancies_0.3VO₃The strontium Sr vacancy lithium battery has higher specific capacity, because a plurality of defects are introduced due to the increase of the strontium Sr vacancy, the strontium Sr vacancy lithium battery is used as an additional lithium storage active site, and the specific capacity is improved; in addition, the vacancy can also promote the transmission of lithium ions, so that the high multiplying power of 220mAh/g can be kept at 5A/g under high current density, and therefore, the non-stoichiometric Sr ratio_0.3VO₃Has better electrochemical performance.

Example 6

Using non-stoichiometric ratios x>1, although the perovskite can contain a certain amount of strontium Sr to form over-stoichiometric Sr_1.2VO₃Partial polymerization of a portion of the strontium Sr still produces impurity Sr₃V₂O₈As shown in fig. 21, when the nonstoichiometric ratio x of strontium Sr to vanadium V is 1.2, the XRD chart shows that SrVO is contained in the material₃And Sr₃V₂O₈Two phases; as shown in FIG. 22, Sr_1.2VO₃+Sr₃V₂O₈The structure of the blended material is flaky powder, and a large number of nano-particles are arranged on the surface of the flaky powder. The experiment shows that when the metal Sr and the metal V are in stoichiometricWhen the ratio is more than 1, a certain amount of Sr segregation occurs to excess Sr, so that Sr is easily generated₃V₂O₈Or Sr₆V₆O₁₉Iso-oxidation phase of Sr₆V₆O₁₉The oxide phase is usually present at high temperature and is easily oxidized to Sr when exposed to air at low temperature₃V₂O₈An oxidized phase.

The non-stoichiometric strontium vanadate Sr is adopted_1.2VO₃And impurity Sr₃V₂O₈The electrochemical performance of the mixed-phase crystal material of the phases as a lithium battery is tested: the mixed-phase crystal material, the conductive agent super P and the binder PVDF are prepared according to the following steps of 98:0:2 to form an electrode, and the rest steps are the same as the example 1, and as shown in figure 23, the reversible specific capacity can reach 310 mAh/g.

Strontium vanadate SrVO compared to the standard stoichiometric ratio in example 1₃The specific capacity and rate are reduced when excess strontium Sr is contained, which is due to two reasons: (1) too many strontium Sr atoms occupy the octahedral gaps or surroundings, resulting in that the lithium ion diffusion channel inside the unit cell is hindered, and some active sites are occupied by strontium Sr;

(2) impurity Sr₃V₂O₈The phase is a semiconductor phase, and the conductivity of the phase is low, so that the transmission of electrons is not facilitated, and the sample has low electrochemical performance. Therefore, in practical application, SrxVO with x being less than 1 is adopted as close as possible₃The sample is used as an electrochemically active substance.

Example 7

Preparing strontium vanadate SrVO by adopting sol-gel method or solid phase method₃When the non-stoichiometric ratio x<At 0.3, V is produced since Sr is less than the perovskite structure tolerance₂O₃Phase or VO₂And/or VO_yWherein VO is_yThe value range of y in the vanadium oxide of (1)<y<1.5. In the preparation of strontium vanadate SrVO₃When the thermal reduction temperature is high, the V valence of the vanadium oxide is easily from + 4-valent VO₂Reduction to + 3V₂O₃Further increase in temperature will reduce to +2VO. As shown in fig. 24, when the nonstoichiometric ratio x of strontium Sr to vanadium V is 0.1, the XRD chart shows that the material contains Sr_0.3VO₃And V₂O₃Two phases; as shown in FIG. 25, Sr_0.3VO₃And V₂O₃The structure of the blended material is sheet-shaped, and each layer of sheet is composed of interconnected nano-particles.

The non-stoichiometric strontium vanadate Sr is adopted_0.3VO₃And impurity V₂O₃The electrochemical performance of the mixed-phase crystal material of the phases as a lithium battery is tested: the mixed-phase crystal material, the conductive agent super P and the binder PVDF are prepared according to the following steps of 98:0:2 to form an electrode, and the other steps are the same as the step 1, as shown in a) and b) of figure 26, the reversible specific capacity can reach 395 mAh/g.

Strontium vanadate Sr in example 5_0.3VO₃In contrast, when the sample contains a small amount of V₂O₃In phase, there is a certain reduction in specific capacity and rate due to V₂O₃Has lower conductivity and specific capacity, thereby causing the overall capacity of the sample to be reduced. Therefore, the sample containing a small amount of vanadium oxide has slightly lower electrochemical performance, but the highest capacity is higher than 350mAh/g of commercial graphite, so that even a small amount of vanadium oxide can still exert the main advantages of perovskite vanadate, and further maintain excellent electrochemical performance.

Example 8

Using a non-stoichiometric ratio of Sr_0.3VO₃An amorphous material, as shown in fig. 27, when the nonstoichiometric ratio x of strontium Sr to vanadium V is 0.3, the XRD chart shows that the material is a completely amorphous phase; as shown in FIG. 28, the non-stoichiometric ratio Sr_0.3VO₃The amorphous material of (a) is composed of nanosheets connected to one another.

The above-mentioned non-stoichiometric ratio Sr_0.3VO₃As an electrochemical performance test of lithium batteries: the non-stoichiometric ratio Sr_0.3VO₃Amorphous material of (a), conductive agent super P and binder PVDF according to 80: 10: 10 is coated into an electrode, and the content of carbon C is controlled to be 20wt%, the reversible specific capacity can reach 520mAh/g as shown in a) and b) of FIG. 29 in the same steps as example 1.

Compared with the strontium vanadate Sr of the complete crystal structure in example 5_0.3VO₃Crystalline material, amorphous strontium vanadate Sr_0.3VO₃The material has higher specific capacity and higher rate performance, and compared with a crystalline material, an amorphous material has higher-concentration defects which can be used for storing and transmitting lithium ions; when the current density was again returned to 0.05A/g, the specific capacity increased to 500mAh/g with no attenuation, indicating very excellent rate and stability, indicating that the amorphous structure may also have excellent properties.

Example 9

Using non-stoichiometric strontium vanadate Sr_0.3VO₃The amorphous and crystalline composite structure of (a), as shown in figure 30, the XRD chart shows that the material is completely amorphous; as shown in fig. 31, the non-stoichiometric composite structure has a foam-like structure and is composed of nano-sheets and nano-particles connected to each other.

The non-stoichiometric strontium vanadate Sr is adopted_0.3VO₃As an electrochemical performance test of lithium batteries: the non-stoichiometric strontium vanadate Sr_0.3VO₃Amorphous and crystalline composite structure material, conductive agent super P and binder PVDF according to a 98:0:2, the content of carbon C is controlled to be 10 wt%, and the reversible specific capacity can reach 460mAh/g as shown in a) and b) of the graph 32 in the same steps as the example 1.

Compared with the crystalline Sr in example 5_0.3VO₃And amorphous Sr in example 8_0.3VO₃Material, non-stoichiometric ratio Sr_0.3VO₃Amorphous and crystalline blend materials have higher and lower capacities than crystalline but, in contrast, crystalline Sr_0.3VO₃Lower voltage and thus higher voltage when a full cell is constructed; and amorphous Sr_0.3VO₃Higher voltage and thus lower voltage when a full cell is constructed; amorphous and crystallineThe voltage of the mixed phase is between the two.

Therefore, the amorphous/crystalline ratio can be adjusted and controlled, and the voltage of the battery can be adjusted and controlled.

In conclusion, the battery cathode material with high specific capacity, high multiplying power, high stability and high safety can be obtained, and the requirements of the power battery on performance and safety are met.

The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A vanadate-based battery negative electrode active material with a perovskite structure is characterized in that: the negative electrode material is alkaline earth vanadate AVO with a perovskite structure₃(A ═ Ca, Sr, Ba), the alkaline earth vanadate AVO₃Comprising calcium vanadate CaVO₃Strontium vanadate SrVO₃Barium vanadate BaVO₃One or more of (a).

2. The perovskite-structure vanadate-based battery negative electrode active material according to claim 1, wherein: the alkaline earth vanadate AVO with the perovskite structure₃(A ═ Ca, Sr, Ba) includes perovskite-structured alkaline earth vanadate A in which the ratio of the non-stoichiometric numbers of alkaline earth metal source A to vanadium source V is x_xVO₃(A＝Ca，Sr，Ba)。

3. The perovskite-structure vanadate-based battery negative electrode active material according to claim 2, wherein: the value range of the ratio x of the non-stoichiometric number is 0.3 to 1.2.

4. According to claim 1The perovskite-structure vanadate-based battery negative electrode active material is characterized in that: the alkaline earth vanadate AVO with the perovskite structure₃(a ═ Ca, Sr, Ba) includes crystalline, amorphous, and/or mixed crystalline and amorphous structures.

5. The perovskite-structure vanadate-based battery negative electrode active material according to any one of claims 1 to 4, wherein: the alkaline earth vanadate AVO with the perovskite structure₃(A ═ Ca, Sr, Ba) includes carbon-containing perovskite-structured alkaline earth vanadate AVO₃The composite material of (1).

6. The perovskite structure vanadate-based battery negative electrode active material according to claim 5, wherein: the mass fraction of C ranges from 0 to 20 wt%.

7. The perovskite-structure vanadate-based battery negative electrode active material according to claims 1 and 2, wherein: the alkaline earth vanadate AVO with the perovskite structure₃(A ═ Ca, Sr, Ba), contains V₂O₃、VO₂And/or VO_yAnd include Sr₃V₂O₈And/or Sr₆V₆O₁₁Of the oxidation phase of (a).

8. The perovskite structure vanadate-based battery negative electrode active material according to claim 7, wherein: the VO_yThe value range of y in the vanadium oxide of (1)<y<1.5。

9. The perovskite-structure vanadate-based battery negative electrode active material according to claim 1, wherein: the alkaline earth vanadate AVO with the perovskite structure₃Use of (a ═ Ca, Sr, Ba) as a battery negative electrode active material.

10. A vanadate base of perovskite structure according to claim 9A battery negative active material characterized by: the battery cathode material comprises alkaline earth vanadate AVO (AVO)₃: conductive agent: 70-99% of binder: 20-0: 10 to 1.