Power-type chromium oxide and its preparation method and application

Abstract

This invention discloses a power-type chromium oxide, its preparation method, and its application. The method includes: S1, adding an acid solution to a dichromate solution, evaporating and crystallizing the reaction solution to obtain an evaporated chromium trioxide component; dissolving the evaporated component in water to obtain a chromium-containing solution, heating it to 80℃~200℃ and holding it at that temperature for a period of time, then cooling it to 0~20℃ at a certain cooling rate, and obtaining porous spherical chromium trioxide through low-temperature crystallization; S2, subjecting the porous spherical chromium trioxide to a first heat treatment in an oxygen environment to obtain a chromium oxide mixture powder; S3, adding the aforementioned powder to deionized water, ultrasonicating, filtering and drying the mixture, then subjecting it to a second heat treatment in an oxygen environment, and obtaining a power-type chromium oxide after cooling and grinding. The chromium oxide obtained by this invention has high power characteristics and low rate capacity characteristics, which is beneficial for the preparation of high specific energy and high power primary batteries. Furthermore, the preparation method is simple and suitable for large-scale industrial production and widespread application.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical materials, specifically relating to a power-type chromium oxide, its preparation method, and its application. Background Technology

[0002] Chromium oxide (Cr8O 21 As a novel cathode material for lithium primary batteries, it has a high discharge voltage plateau (>3.0V, vs. Li) + Li, with its advantages such as no voltage hysteresis at low and medium rates, is a promising cathode material that combines high specific energy and high power.

[0003] However, the preparation process of chromium oxides is still immature, and the electrochemical performance (discharge specific capacity and cycle performance) of chromium oxides is greatly affected by the preparation conditions. Currently, to improve the electrochemical performance of chromium oxide cathodes, existing research mainly focuses on modifying the material preparation conditions, such as the high-temperature calcination temperature and time of chromium trioxide, to change the structural composition of the chromium oxide; or improving the conductivity of the material through carbon coating to suppress the problem of CrO3's easy solubility in organic donor solvents. However, the problems of low discharge specific capacity and low rate performance of chromium oxides remain unresolved. In actual tests, existing chromium oxides (Cr8O... 21 The discharge specific capacity is mostly below 400mAh / g (0.1C rate), and the rate performance and cycle performance of the battery are poor.

[0004] Therefore, it is necessary to develop Cr8O with high specific capacity and high rate performance. 21 Chromium oxide cathode materials have significant research value and practical application potential. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a power-type chromium oxide, its preparation method, and its application. The chromium oxide prepared by the method of the present invention has high power characteristics and high specific capacity characteristics, which is beneficial for the preparation of high specific energy and high power lithium primary batteries. Moreover, the preparation method is simple and suitable for large-scale industrial production and widespread application.

[0006] To achieve the above objectives, the present invention first provides a method for preparing power-type chromium oxide, comprising the following steps:

[0007] S1, Preparation of porous spherical chromium trioxide:

[0008] An acid solution is added to a dichromate solution to carry out a reaction. The resulting reaction solution is evaporated, crystallized, and filtered to obtain the chromium trioxide evaporated component.

[0009] The chromium trioxide evaporation component is dissolved in water to obtain a chromium-containing solution. The chromium-containing solution is heated to 80℃~200℃ and kept at that temperature for a period of time. Then, it is cooled to 0~20℃ at a certain cooling rate. After low-temperature crystallization and filtration, porous spherical chromium trioxide is obtained.

[0010] S2, Preparation of chromium oxide mixture:

[0011] The porous spherical chromium trioxide obtained in step S1 was subjected to a first heat treatment in an oxygen environment to obtain a chromium oxide mixture powder.

[0012] S3, Preparation of power-type chromium oxide:

[0013] The chromium oxide mixture powder obtained in step S2 is added to deionized water. After the mixture is ultrasonicated, filtered and dried, it is subjected to a second heat treatment in an oxygen environment. After cooling and grinding, power-type chromium oxide is obtained.

[0014] In step S2, the first heat treatment employs a multi-stage heating method with a low heating rate in the low-temperature stage and a high heating rate in the high-temperature stage.

[0015] Preferably, the first heat treatment is as follows: heating to 190°C at 0.1-1°C / min, then heating to 250°C-290°C at 5-20°C / min, and holding at that temperature for 6-20 hours.

[0016] Preferably, the second heat treatment is: heating to 250℃~270℃ at a rate of 0.5~4℃ / min and holding at that temperature for 5h~20h.

[0017] Preferably, in step S1, the cooling rate is 0.5℃ / min to 20℃ / min.

[0018] Preferably, the molar mass ratio of the dichromate to the acid solution is 1:2 to 1:5.

[0019] Preferably, the dichromate solution is any one or a combination of sodium dichromate and potassium dichromate; the acid solution is any one or a combination of concentrated nitric acid and concentrated sulfuric acid.

[0020] Preferably, in step S1, the mass concentration of the chromium-containing solution is 20% to 60%.

[0021] Preferably, in step S3, the ultrasound conditions are: 40℃~80℃, ultrasound for 30min~2h.

[0022] In another aspect, the present invention provides a power-type chromium oxide prepared according to any of the preceding methods.

[0023] In another aspect, the present invention also provides the application of the aforementioned power-type chromium oxide in the preparation of electrodes and batteries.

[0024] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0025] 1. This invention achieves power-type chromium oxide Cr8O through a combination of morphology and crystal phase control. 21 The preparation of materials involves synergistically optimizing ion transport velocity, material composition, and crystal phase integrity, simultaneously improving power characteristics and low-rate capacity characteristics, ultimately facilitating the fabrication of lithium primary batteries with both high specific energy and high power. Specifically, this includes:

[0026] (1) This invention regulates the particle morphology and size of the raw material chromium trioxide by adjusting the low-temperature recrystallization rate, constructing a porous secondary spherical particle morphology, thereby improving the chromium oxide Cr8O prepared by this invention. 21 Macroscopically, the larger particle size is beneficial for increasing tap density; at the same time, it also has the characteristic of smaller particle size of its constituent units, which is beneficial for increasing ion transport rate, and ultimately beneficial for the preparation of high specific energy electrodes.

[0027] (2) In view of the problem that the melting point temperature of chromium trioxide is lower than its decomposition temperature, which makes the material particles easy to agglomerate, the present invention adopts a heat treatment technology that combines slow heating in the low temperature section and rapid heating in the high temperature section. This makes the porous spherical morphology less likely to collapse during the heat treatment process, suppresses the phenomenon of material particles agglomerating and agglomerating due to melting reaction during the heating of chromium trioxide raw materials, effectively controls the particle morphology and size of the product, thereby improving the power characteristics of the material.

[0028] (3) The present invention combines multi-step heat treatment and water washing process to significantly reduce the content of free chromium trioxide in the product, improve the purity and crystal phase integrity of chromium oxide material components, thereby improving the capacity characteristics of the material.

[0029] 2. The power-type chromium oxide Cr8O provided by this invention 21 The preparation process is simple and easy to industrialize, and the prepared materials have excellent electrochemical properties and good market application prospects. Attached Figure Description

[0030] Figure 1 This is a flowchart of the preparation method of the power-type chromium oxide of the present invention.

[0031] Figure 2 This is a SEM image of the chromium trioxide material prepared in Example 1 of the present invention.

[0032] Figure 3 This is a particle size distribution diagram of the power-type chromium oxide material prepared in Example 1 of the present invention.

[0033] Figure 4 The discharge curve of the lithium battery prepared based on the power-type chromium oxide material of Example 1 of the present invention at 0.1C. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Studies have found that chromium oxides (Cr8O) 21 The power characteristics of chromium oxides are closely related to parameters such as the electron / ion transport rate, particle morphology, and crystal integrity of the material. Smaller particle size is beneficial for shortening the lithium-ion diffusion path, improving lithium transport efficiency, and enhancing the rate performance of the material. However, it also reduces the tap density, which is detrimental to the fabrication of high-energy-density electrodes. As described in the background section, current chromium oxides are often synthesized using a solid-state method, i.e., high-temperature calcination of the raw material chromium trioxide. This method cannot effectively control the particle morphology and size of chromium oxides, thus affecting the electrochemical performance of the material. Therefore, there is an urgent need in this field to develop a method for preparing chromium oxides that can achieve control over the particle morphology, size, and crystal structure, and possesses superior power characteristics.

[0036] To address the aforementioned problems, this invention, through extensive experimentation and verification, ultimately provides a method for preparing power-type chromium oxide, such as... Figure 1 As shown, it includes the following steps:

[0037] S1, Preparation of porous spherical chromium trioxide:

[0038] An acid solution is added to a dichromate solution to carry out a reaction. The resulting reaction solution is evaporated, crystallized, and filtered to obtain the chromium trioxide evaporated component.

[0039] The chromium trioxide evaporation component is dissolved in water to obtain a chromium-containing solution. The chromium-containing solution is heated to 80℃~200℃ and kept at that temperature for a period of time. Then, it is cooled to 0~20℃ at a certain cooling rate. After low-temperature crystallization and filtration, porous spherical chromium trioxide is obtained.

[0040] It is important to emphasize that, unlike existing technologies that produce or directly purchase chromium trioxide with a single particle size, the chromium trioxide obtained in this step possesses both a large and small particle size characteristic. Specifically, in this step, the chromium trioxide evaporation component first yields small-sized "primary particle" chromium trioxide. After subsequent heating and low-temperature recrystallization, these particles agglomerate to form larger-sized "secondary particle" porous spherical chromium trioxide. In other words, the large-sized "secondary particle" porous spherical chromium trioxide obtained in step S1 is composed of small-sized "primary particle" chromium trioxide. This facilitates the control of the particle size distribution of the subsequent chromium oxide product, ultimately resulting in the chromium oxide Cr8O prepared by this invention.21 Macroscopically, the larger particle size is beneficial for increasing tap density; at the same time, it also has the characteristic of smaller particle size of its constituent units, which is beneficial for increasing ion transport rate, and ultimately beneficial for the preparation of high specific energy electrodes.

[0041] In some embodiments, the primary particle size is 100 nm to 10 μm, preferably 800 nm to 5 μm; the secondary particle size is 10 μm to 100 μm, preferably 15 μm to 50 μm.

[0042] In some embodiments, the cooling rate is 0.5℃ / min to 20℃ / min. Preferably, the cooling rate is 2℃ / min to 15℃ / min. It should be noted that the particle morphology and size of the porous spherical chromium trioxide can be adjusted by regulating the cooling rate. Specifically, when the cooling rate is faster, the recrystallization rate is faster, resulting in the initial formation of numerous crystal nuclei. The primary particles formed are large and irregular, while the secondary particles formed by agglomeration are smaller. When the cooling rate is slower, the number of crystal nuclei is less, and the primary particles continuously agglomerate to form secondary particles during the crystallization process, with the size of the secondary particles gradually increasing. Therefore, as the cooling rate decreases, the size of the primary particles decreases, and the size of the secondary particles increases.

[0043] In some embodiments, the molar mass ratio of the dichromate to the acid solution is 1:2 to 1:5. The dichromate solution is any one or more combinations of sodium dichromate and potassium dichromate; the acid solution is any one or more combinations of concentrated nitric acid and concentrated sulfuric acid. The concentration of the dichromate solution is 1% to 10%, the concentration of the concentrated sulfuric acid is 96% to 98%, and the concentration of the concentrated nitric acid is 60% to 65%.

[0044] In some embodiments, the mass concentration of the chromium-containing solution is 20% to 60%.

[0045] S2, Preparation of chromium oxide mixture:

[0046] The porous spherical chromium trioxide obtained in step S1 is subjected to a first heat treatment in an oxygen environment, so that the chromium trioxide undergoes an oxidative decomposition reaction at a certain temperature to obtain a mixture powder of chromium oxides in a low valence state.

[0047] The first heat treatment employs a multi-stage heating method with a low heating rate in the low-temperature stage and a high heating rate in the high-temperature stage. During the rapid heating in the high-temperature stage, the material rapidly decomposes before it has a chance to completely melt, forming Cr8O. 21This design prevents the porous spherical morphology from collapsing during heat treatment, inhibiting the agglomeration and caking of chromium trioxide particles due to melting reaction during heating. This effectively controls the particle size and morphology of the product, thereby improving the material's power characteristics. In some embodiments, the first heat treatment involves heating to 190°C at 0.1–1°C / min, then heating to 250°C–290°C at 5–20°C / min, and holding at that temperature for 6–20 hours.

[0048] S3, Preparation of power-type chromium oxide:

[0049] The chromium oxide mixture powder obtained in step S2 is added to deionized water. After the mixture is ultrasonicated, filtered and dried, it is subjected to a second heat treatment in an oxygen environment. After cooling and grinding, power-type chromium oxide is obtained.

[0050] It should be noted that the chromium oxide mixture powder obtained in step S2 may contain unreacted residual chromium trioxide, as chromium trioxide is readily soluble in water while chromium oxide (Cr8O) is soluble in water. 21 Due to its poor solubility in water, this step first adds the chromium oxide mixture powder obtained in step S2 to deionized water. After ultrasonic and filtration treatment, the residual chromium trioxide in step S2 is removed to improve the purity of the low-valence chromium oxide in the material. Then, through a second heat treatment, the purity of the chromium oxide and the integrity of the crystal structure are further improved, and defects (including vacancies on the material surface and crystallinity) are reduced, thereby improving the power characteristics of the chromium oxide material of the present invention and facilitating the fabrication of high specific energy electrodes.

[0051] In some embodiments, the second heat treatment is: heating to 250°C to 270°C at a rate of 0.5 to 4°C / min and holding at that temperature for 5 to 20 hours.

[0052] In some embodiments, the ultrasonic conditions are: ultrasonication at 40℃~80℃ for 30min~2h to promote the dispersion of the mixed powder in the aqueous solution and accelerate the dissolution of residual chromium trioxide in the powder into the aqueous solution.

[0053] In some embodiments, the particle size of the power-type chromium oxide is 1 μm to 30 μm, preferably 2 to 15 μm.

[0054] The technical features of the present invention will be described in detail below with reference to embodiments and accompanying drawings. Unless otherwise specified, the instruments and materials described in the embodiments below can be obtained commercially.

[0055] Example 1

[0056] A method for preparing a power-type chromium oxide includes the following steps:

[0057] S1, Preparation of porous spherical chromium trioxide:

[0058] Concentrated nitric acid of 65% concentration was added to a 3% potassium dichromate solution at a molar ratio of 1:3 and the reaction was carried out for 8 hours. The reaction solution was then evaporated and crystallized at 110℃ and filtered to obtain the chromium trioxide evaporated component.

[0059] The chromium trioxide evaporated component was added back to deionized water to dissolve, resulting in a chromium-containing solution with a mass concentration of 40%. The chromium-containing solution was heated to 100°C and held at that temperature for 30 min. Then, it was placed in a low-temperature chamber and cooled to 10°C at a rate of 8°C / min. After the crystals were completely precipitated, the solution was filtered to obtain porous spherical chromium trioxide (particle size characterization approximately 20 μm).

[0060] S2, Preparation of chromium oxide mixture:

[0061] Using the product prepared in step S1 as raw material, the temperature was increased to 190°C at 0.2°C / min in an oxygen environment, and then increased to 270°C at 15°C / min. The temperature was maintained at this temperature for 8 hours, and then naturally cooled to obtain a chromium oxide mixture powder.

[0062] S3, Preparation of power-type chromium oxide:

[0063] A mixture of chromium oxide powders was added to deionized water, sonicated at 60°C for 1 hour, filtered and dried, and then heated to 260°C at a rate of 1°C / min in an oxygen environment. After holding at this temperature for 12 hours, the mixture was naturally cooled and ground to obtain power-type chromium oxide Cr8O. 21 .

[0064] The chromium trioxide material prepared in this embodiment was characterized by SEM, such as... Figure 2 As shown, the material exhibits a porous, secondary spherical particle morphology. Regarding Cr8O... 21 The particle size of chromium oxide materials is characterized, such as... Figure 3 As shown, Cr8O 21 The D50 of the chromium oxide material is approximately 12.6 μm.

[0065] Example 2

[0066] A method for preparing a power-type chromium oxide includes the following steps:

[0067] S1, Preparation of porous spherical chromium trioxide:

[0068] Concentrated nitric acid of 65% concentration was added to a 3% potassium dichromate solution at a molar ratio of 1:3 and the reaction was carried out for 8 hours. The reaction solution was then evaporated and crystallized at 110℃ and filtered to obtain the chromium trioxide evaporated component.

[0069] The chromium trioxide evaporated component was added back to deionized water to dissolve, resulting in a chromium-containing solution with a mass concentration of 50%. The chromium-containing solution was heated to 120°C and held for 50 min. Then, the solution was cooled to 10°C at a rate of 2°C / min. After the crystals were completely precipitated, the solution was filtered to obtain porous spherical chromium trioxide (particle size characterization approximately 40 μm).

[0070] S2, Preparation of the chromium oxide mixture: This step is the same as the preparation conditions in Example 1.

[0071] S3, Preparation of power-type chromium oxide: This step is the same as the preparation conditions in Example 1.

[0072] Example 3

[0073] A method for preparing a power-type chromium oxide includes the following steps:

[0074] S1, Preparation of porous spherical chromium trioxide: This step is the same as the preparation conditions in Example 1.

[0075] S2, Preparation of chromium oxide mixture:

[0076] Using the product prepared in step S1 as raw material, the temperature was increased to 190°C at 0.8°C / min in an oxygen environment, and then increased to 265°C at 10°C / min. The temperature was maintained at this temperature for 14 hours, and then naturally cooled to obtain a chromium oxide mixture powder.

[0077] S3, Preparation of power-type chromium oxide: This step is the same as the preparation conditions in Example 1.

[0078] Example 4

[0079] A method for preparing a power-type chromium oxide includes the following steps:

[0080] S1, Preparation of porous spherical chromium trioxide: This step is the same as the preparation conditions in Example 1.

[0081] S2, Preparation of the chromium oxide mixture: This step is the same as the preparation conditions in Example 1.

[0082] S3, Preparation of power-type chromium oxide:

[0083] A mixture of chromium oxide powders was added to deionized water and sonicated at 40°C for 2 hours. After filtration and drying, the mixture was heated to 260°C at a rate of 0.5°C / min in an oxygen environment and held at that temperature for 15 hours. After natural cooling and grinding, a high-performance Cr8O3 was obtained. 21 Chromium oxides.

[0084] Comparative Example 1

[0085] A method for preparing a power-type chromium oxide includes the following steps:

[0086] S1, Preparation of porous spherical chromium trioxide:

[0087] Concentrated nitric acid of 65% concentration was added to a 3% potassium dichromate solution at a molar ratio of 1:3 and the reaction was carried out for 8 hours. The reaction solution was then evaporated and crystallized at 110℃ and filtered to obtain the chromium trioxide evaporated component.

[0088] The chromium trioxide evaporated component was added back to deionized water to dissolve, resulting in a chromium-containing solution with a mass concentration of 10%. The chromium-containing solution was heated to 60°C and held for 20 min. Then, the solution was cooled to 30°C at a cooling rate of 0.05°C / min. After the crystals were completely precipitated, the solution was filtered to obtain porous spherical chromium trioxide (particle size characterization approximately 300 μm).

[0089] Steps S2 and S3 are the same as those in Example 1.

[0090] Comparative Example 2

[0091] A method for preparing a power-type chromium oxide includes the following steps:

[0092] S1, Preparation of porous spherical chromium trioxide: This step is the same as the preparation conditions in Example 1.

[0093] S2, Preparation of chromium oxide mixture:

[0094] Using the product prepared in step S1 as raw material, the temperature was increased to 190°C at 3°C / min in an oxygen environment, and then increased to 265°C at 3°C / min. The temperature was maintained at this temperature for 4 hours, and then naturally cooled to obtain a chromium oxide mixture powder.

[0095] S3, Preparation of power-type chromium oxide: This step is the same as the preparation conditions in Example 1.

[0096] Comparative Example 3

[0097] A method for preparing a power-type chromium oxide includes the following steps:

[0098] S1, Preparation of porous spherical chromium trioxide: This step is the same as the preparation conditions in Example 1.

[0099] S2, Preparation of the chromium oxide mixture: This step is the same as the preparation conditions in Example 1.

[0100] S3, Preparation of power-type chromium oxide:

[0101] A mixture of chromium oxide powders was added to deionized water and sonicated at 20°C for 2 hours. After filtration and drying, the mixture was heated to 260°C at a rate of 10°C / min in an oxygen environment and held at that temperature for 4 hours. After natural cooling and grinding, a power-type chromium oxide Cr8O was obtained.21 .

[0102] Comparative Example 4

[0103] Commercially available chromium trioxide was used directly for steps S2 and S3, with the same preparation conditions as in Example 1. The commercially available chromium trioxide (purchased from Sinopharm, analytical grade, >99%) was in a blocky crystalline morphology with a particle size of approximately 120 μm.

[0104] The Cr8O prepared in Examples 1-5 and Comparative Examples 1-4 21 Chromium oxide materials were used for subsequent lithium battery assembly and fabrication, and their discharge capacities at 0.1C and 5C were tested. The data obtained are shown in Table 1. Compared with the comparative examples and existing technologies, the Cr8O materials prepared based on Examples 1-4 of this invention... 21 Lithium batteries assembled from chromium oxide materials exhibit superior performance, with discharge capacities exceeding 400 mAh / g at 0.1C.

[0105] Figure 4 Cr8O prepared based on Example 1 21 The discharge curves of the lithium battery prepared with chromium oxide materials at 0.1C show that the median voltage plateau of the lithium battery is about 3.03V, and the discharge specific capacity of the material reaches 431mAh / g, demonstrating excellent electrochemical performance.

[0106] Table 1 Comparison of lithium battery performance based on chromium oxides prepared in the examples and comparative examples.

[0107] sample Discharge capacity at 0.1C (mAh / g) Discharge capacity at 5C (mAh / g) Example 1 431 358 Example 2 422 346 Example 3 420 329 Example 4 418 311 Comparative Example 1 366 241 Comparative Example 2 321 226 Comparative Example 3 334 207 Comparative Example 4 310 189

[0108] In summary, the preparation method of this invention achieves high-power chromium oxide Cr8O through a combination of morphology and crystal phase control. 21 The preparation of this material synergistically optimizes ion transport velocity, material composition, and crystal phase integrity, simultaneously improving the material's power characteristics and low-rate capacity, ultimately facilitating the fabrication of lithium primary batteries with both high specific energy and high power. Furthermore, the preparation method of this invention is simple and suitable for large-scale industrial production and widespread application.

[0109] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a power-type chromium oxide, characterized by, The method comprises the following steps: S1, preparation of porous spherical chromium trioxide: An acid solution is added to the dichromate solution to react, and the obtained reaction solution is evaporated and crystallized, filtered to obtain an evaporation component of chromium trioxide; The evaporation component of chromium trioxide is dissolved in water to obtain a chromium-containing solution, the chromium-containing solution is heated to 80-200℃ and kept for a period of time, then cooled to 0-20℃ at a certain cooling rate, and then low-temperature crystallization and filtration are performed to obtain porous spherical chromium trioxide, wherein the mass concentration of the chromium-containing solution is 20-60%, and the certain cooling rate is 0.5-20℃ / min; S2, preparation of chromium oxide mixture: The porous spherical chromium trioxide obtained in step S1 is subjected to a first heat treatment in an oxygen environment to obtain a chromium oxide mixture powder, wherein the first heat treatment is as follows: heating to 190℃ at 0.1-1℃ / min, then heating to 250-290℃ at 5-20℃ / min, and keeping for 6-20 h; S3, preparation of power type chromium oxide: The chromium oxide mixture powder obtained in step S2 is added into deionized water, the mixed solution is subjected to ultrasonic treatment, filtration and drying, and then subjected to a second heat treatment in an oxygen environment, and after cooling and grinding, a power type chromium oxide is obtained, wherein the power type chromium oxide is Cr8O 21 , and the second heat treatment is heating at a rate of 0.5-4 ℃ / min to 250-270 ℃ and holding for 5-20 h.

2. The method for preparing power-type chromium oxide as described in claim 1, characterized in that, The molar ratio of the dichromate to the acid solution is 1:2-1:

5.

3. The method for preparing power-type chromium oxide as described in claim 1, characterized in that, The dichromate solution is any one or a combination of multiple of sodium dichromate and potassium dichromate; and the acid solution is any one or a combination of multiple of concentrated nitric acid and concentrated sulfuric acid.

4. The method for preparing power-type chromium oxide as described in claim 1, characterized in that, In step S3, the ultrasonic conditions are as follows: ultrasonic treatment at 40-80℃ for 30 min-2 h.

5. A power type chromium oxide prepared by the preparation method according to any one of claims 1-4.

6. Application of the power type chromium oxide according to claim 5 in preparation of electrodes and batteries.

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