Modification method of electrolytic manganese dioxide as positive electrode active material and lithium manganese battery

Abstract

The present application provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, and a lithium manganese battery, which relate to the field of lithium manganese batteries. The method for modifying electrolytic manganese dioxide, a positive electrode active material, comprises: mixing raw materials including electrolytic manganese dioxide positive electrode material, lithium carbonate and pure water, and then ball milling to obtain modified electrolytic manganese dioxide; mixing the modified electrolytic manganese dioxide and acetonitrile, and soaking to obtain the modified electrolytic manganese dioxide positive electrode active material. The raw materials of the lithium manganese battery include the modified electrolytic manganese dioxide positive electrode active material obtained by the method for modifying electrolytic manganese dioxide, a positive electrode active material. The method for modifying electrolytic manganese dioxide, a positive electrode active material, provided in the present application, can effectively remove impurities in electrolytic manganese dioxide, increase the cycle performance of lithium manganese batteries, and solve the problem of battery bulging.

Description

Technical Field

[0001] The present application relates to the field of lithium manganese batteries, and in particular to a modification method of electrolytic manganese dioxide, a positive electrode active material, and a lithium manganese battery. Background Art

[0002] Lithium-manganese batteries that use MnO2 as the positive electrode active material, because the positive electrode material MnO2 of lithium-manganese batteries is mostly electrolytic MnO2, it is easy to introduce substances such as sulfate and sodium ions in the process of producing electrolytic MnO2. The sulfate ions in the pores usually exist as hydrogen sulfate. Sulfate and sodium ions are difficult to be easily removed in the narrow pores of electrolytic MnO2, which is easy to produce side reactions and cause the soft-pack battery to bloat. Summary of the invention

[0003] The purpose of the present application is to provide a modification method of electrolytic manganese dioxide, a positive electrode active material, and a lithium manganese battery to solve the above problems.

[0004] To achieve the above objectives, this application adopts the following technical solutions:

[0005] A method for modifying electrolytic manganese dioxide, a positive electrode active material, comprising:

[0006] Mixing raw materials including electrolytic manganese dioxide positive electrode material, lithium carbonate and pure water, and then ball milling to obtain modified electrolytic manganese dioxide;

[0007] The modified electrolytic manganese dioxide and acetonitrile are mixed and soaked to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0008] Preferably, the amount of lithium carbonate used is 0.5wt%-1.5wt% of the mass of the electrolytic manganese dioxide positive electrode material.

[0009] Preferably, the amount of pure water used is 3wt%-8wt% of the mass of the electrolytic manganese dioxide positive electrode material.

[0010] Preferably, the ball milling temperature is 15°C-35°C.

[0011] Preferably, the ball milling time is 2h-8h.

[0012] Preferably, the ball milling further comprises:

[0013] The mixed material is subjected to solid-liquid separation to obtain a solid material, and then the solid material is washed with water and dried to obtain the modified electrolytic manganese dioxide.

[0014] Preferably, the soaking time is 12h-36h.

[0015] The present application also provides a lithium manganese dioxide battery, the raw material of which includes modified electrolytic manganese dioxide obtained by using the modification method of electrolytic manganese dioxide as a positive electrode active material.

[0016] Compared with the prior art, the beneficial effects of this application include:

[0017] The modification method of the positive electrode active material manganese dioxide provided in the present application increases the contact area between lithium carbonate and manganese dioxide during the flow of pure water medium, thereby increasing the reaction efficiency and reaction sufficiency; during the reaction process, the slightly soluble lithium ions and carbonate ions of lithium carbonate enter the pores of manganese dioxide, react with the hydrogen sulfate ions and sodium ions in the pores of manganese dioxide, continuously consume hydrogen ions, and release sulfate; lithium ions occupy the vacancies of sodium ions because their radius is smaller than that of sodium ions, and release sodium ions, while generating carbon dioxide and water as flow medium, continuously promoting the dissolution and ionization of lithium carbonate, while continuously consuming hydrogen ions to release sulfate and sodium ions; acetonitrile small molecules can cooperate with the vacancies of the active sites Mn of manganese dioxide, while eliminating water molecules, avoiding water absorption of the modified manganese dioxide positive electrode active material, reducing side reactions, lowering the internal resistance of the battery, and avoiding flatulence.

[0018] The present application adopts the above-mentioned electrolytic manganese dioxide positive electrode active material modification method to prepare modified electrolytic manganese dioxide, which has good cycle performance and few side reactions, and can be used to prepare lithium manganese batteries with excellent electrical properties.

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the data and test results required for use in the embodiments are briefly introduced below. It should be understood that the following only shows certain embodiments of the present application and should not be regarded as limiting the scope of the present application. DETAILED DESCRIPTION

[0020] As used herein:

[0021] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0022] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0023] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0024] In these examples, parts and percentages are by mass unless otherwise indicated.

[0025] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0026] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0027] A method for modifying electrolytic manganese dioxide, a positive electrode active material, comprising:

[0028] Mixing raw materials including electrolytic manganese dioxide positive electrode material, lithium carbonate and pure water, and then ball milling to obtain modified electrolytic manganese dioxide;

[0029] The modified electrolytic manganese dioxide and acetonitrile are mixed and soaked to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0030] In an optional embodiment, the amount of lithium carbonate used is 0.5wt%-1.5wt% of the mass of the electrolytic manganese dioxide positive electrode material.

[0031] Optionally, the amount of the lithium carbonate can be 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt% or any value between 0.5wt% and 1.5wt% of the mass of the electrolytic manganese dioxide positive electrode material.

[0032] In an optional embodiment, the amount of pure water used is 3wt%-8wt% of the mass of the electrolytic manganese dioxide positive electrode material.

[0033] Optionally, the amount of pure water used can be 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt% or any value between 3wt% and 8wt% of the mass of the electrolytic manganese dioxide positive electrode material.

[0034] In an optional embodiment, the ball milling temperature is 15°C-35°C.

[0035] The solubility of lithium carbonate in aqueous solution is inversely proportional to the temperature. It does not need to be carried out at high temperature, and ball milling can be carried out at a lower temperature.

[0036] Optionally, the ball milling temperature may be 15°C, 20°C, 25°C, 30°C, 35°C or any value between 15°C and 35°C.

[0037] In an optional embodiment, the ball milling time is 2h-8h.

[0038] Optionally, the ball milling time can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or any value between 2 h and 8 h.

[0039] In an optional embodiment, the ball milling further comprises:

[0040] The mixed material is subjected to solid-liquid separation to obtain a solid material, and then the solid material is washed with water and dried to obtain the modified electrolytic manganese dioxide.

[0041] In an optional embodiment, the soaking time is 12h-36h.

[0042] Optionally, the soaking time can be 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h or any value between 12h and 36h.

[0043] The present application also provides a lithium manganese dioxide battery, the raw material of which includes modified electrolytic manganese dioxide obtained by using the modification method of electrolytic manganese dioxide as a positive electrode active material.

[0044] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0045] Example 1

[0046] This embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps:

[0047] S1. Electrolytic manganese dioxide and lithium carbonate, the positive electrode active materials of lithium batteries, are ball-milled and mixed uniformly in a pure water medium to obtain a mixture; the amount of lithium carbonate is 1.2wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water is 6wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball-milling temperature is 30° C., and the ball-milling time is 8h;

[0048] The mixed material is filtered, washed with water, and dried to obtain the product modified electrolytic manganese dioxide;

[0049] S2. Soak the product modified electrolytic manganese dioxide in acetonitrile solvent for 36 hours. The acetonitrile small molecules are embedded in the pores of the product manganese dioxide and react with the active sites of manganese dioxide to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0050] Example 2

[0051] This embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps:

[0052] S1. Electrolytic manganese dioxide and lithium carbonate, the positive electrode active materials of lithium batteries, are ball-milled and mixed uniformly in a pure water medium to obtain a mixture; the amount of lithium carbonate is 1.5wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water is 3wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball-milling temperature is 35° C., and the ball-milling time is 2h;

[0053] The mixed material is filtered, washed with water, and dried to obtain the product modified electrolytic manganese dioxide;

[0054] S2. Soak the product modified electrolytic manganese dioxide in acetonitrile solvent for 24 hours, so that the acetonitrile small molecules are embedded in the pores of the product manganese dioxide and react with the active sites of manganese dioxide to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0055] Example 3

[0056] This embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps:

[0057] S1. Electrolytic manganese dioxide and lithium carbonate, the positive electrode active materials of lithium batteries, are ball-milled and mixed uniformly in a pure water medium to obtain a mixture; the amount of lithium carbonate is 0.5wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water is 4wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball-milling temperature is 15° C., and the ball-milling time is 6h;

[0058] The mixed material is filtered, washed with water, and dried to obtain the product modified electrolytic manganese dioxide;

[0059] S2. Soak the product modified electrolytic manganese dioxide in acetonitrile solvent for 12 hours, so that the acetonitrile small molecules are embedded in the pores of the product manganese dioxide and react with the active sites of manganese dioxide to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0060] Example 4

[0061] This embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps:

[0062] S1. Electrolytic manganese dioxide and lithium carbonate, the positive electrode active materials of lithium batteries, are ball-milled and mixed uniformly in a pure water medium to obtain a mixture; the amount of lithium carbonate is 0.8wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water is 8wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball-milling temperature is 25° C., and the ball-milling time is 4h;

[0063] The mixed material is filtered, washed with water, and dried to obtain the product modified electrolytic manganese dioxide;

[0064] S2. Soak the product modified electrolytic manganese dioxide in acetonitrile solvent for 20 hours. The acetonitrile small molecules are embedded in the pores of the product manganese dioxide and react with the active sites of manganese dioxide to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0065] Comparative Example 1

[0066] Compared with Example 1, this embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps: ball-milling the electrolytic manganese dioxide, a positive electrode active material for a lithium battery, without adding lithium carbonate, and then soaking it in an acetonitrile solvent for 36 hours to obtain a modified electrolytic manganese dioxide positive electrode active material.

[0067] Comparative Example 2

[0068] Compared with Example 1, this embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps: ball-milling the electrolytic manganese dioxide, a positive electrode active material of a lithium battery, and lithium carbonate in a pure water medium to uniformly obtain a mixture; the amount of lithium carbonate used is 1.2wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water used is 6wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball milling temperature is 30°C, and the ball milling time is 8h; after filtering, washing, and drying the mixture, a product modified electrolytic manganese dioxide is obtained, and the product modified electrolytic manganese dioxide is not soaked in acetonitrile solvent.

[0069] Example 5

[0070] This embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps:

[0071] S1. Electrolytic manganese dioxide and lithium carbonate, the positive electrode active materials of lithium batteries, are ball-milled and mixed uniformly in a pure water medium to obtain a mixture; the amount of lithium carbonate is 1.5wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water is 3wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball-milling temperature is 35° C., and the ball-milling time is 2h;

[0072] The mixed material is filtered, washed with water, and dried to obtain the product modified electrolytic manganese dioxide;

[0073] S2. Soak the product modified electrolytic manganese dioxide in acetonitrile solvent for 12 hours, so that the acetonitrile small molecules are embedded in the pores of the product manganese dioxide and react with the active sites of manganese dioxide to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0074] Example 6

[0075] This embodiment provides a method for modifying electrolytic manganese dioxide, a positive electrode active material, which specifically includes the following steps:

[0076] S1. Electrolytic manganese dioxide and lithium carbonate, the positive electrode active materials of lithium batteries, are ball-milled and mixed uniformly in a pure water medium to obtain a mixture; the amount of lithium carbonate is 1.0wt% of the mass of the electrolytic manganese dioxide positive electrode material, the amount of pure water is 4wt% of the mass of the electrolytic manganese dioxide positive electrode material, the ball-milling temperature is 15° C., and the ball-milling time is 6h;

[0077] The mixed material is filtered, washed with water, and dried to obtain the product modified electrolytic manganese dioxide;

[0078] S2. Soak the product modified electrolytic manganese dioxide in acetonitrile solvent for 12 hours, so that the acetonitrile small molecules are embedded in the pores of the product manganese dioxide and react with the active sites of manganese dioxide to obtain the modified electrolytic manganese dioxide positive electrode active material.

[0079] Experimental example

[0080] The modified electrolytic manganese dioxide prepared by the modification method in 2 comparative examples and 6 examples was used as the positive electrode active material, and the battery was prepared according to the following method: 91wt% of modified electrolytic manganese dioxide, 6wt% of conductive agent acetylene black, 2.7wt% of polytetrafluoroethylene, and 0.3wt% of sodium polyacrylate were mixed, granulated, and then sliced, dried to obtain a positive electrode cake, with metal lithium as the negative electrode, a glass fiber separator, 1mol / L lithium perchlorate / propylene carbonate + ethylene glycol dimethyl ether (volume ratio 1:1) as the electrolyte, and assembled into a CR2032 lithium battery in a drying room with a dew point below -30°. The ACIR impedance value (Ω) of the battery, the static internal resistance (Ω) of the battery, and the battery performance after storage at 60°C were evaluated. Table 1 records the change in the internal resistance of the CR2032 lithium battery obtained in Examples 1-6 and Comparative Examples 1-2 and the battery bloating after storage at 60°C for 5 days (the thickness change at a certain point of the battery).

[0081] Table 1 Test data

[0082]

[0083] Combining Table 1 and Comparative Example 1, it can be seen that there is no lithium carbonate to consume the bisulfate ions, sodium ions, etc. in the manganese dioxide pores, soaking in acetonitrile, the internal resistance is large, side reactions occur, the amount of flatulence is large, the cycle performance is poor, and the overall performance is worse than Example 1; Combining Table 1 and Comparative Example 2, it can be seen that without soaking in acetonitrile, manganese dioxide has active sites that are easy to absorb water, the internal resistance is large, side reactions occur, the amount of flatulence is large, the cycle performance is poor, and the overall performance is worse than Example 2. Combining Table 1 and Example 5, it can be seen that increasing the amount of lithium carbonate, the overall internal resistance is relatively reduced, and the cycle performance is better; Combining Table 1 and Example 6, it can be seen that increasing the soaking time of acetonitrile is conducive to reducing the internal resistance and improving the cycle performance.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0085] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for modifying electrolytic manganese dioxide, a positive electrode active material, It is characterized in that include: The raw materials including electrolytic manganese dioxide positive electrode material, lithium carbonate and pure water are mixed and then ball-milled; after the ball-milling, the mixed material is solid-liquid separated to obtain a solid material, and then the solid material is washed and dried to obtain modified electrolytic manganese dioxide; Mixing the modified electrolytic manganese dioxide and acetonitrile, and soaking to obtain the modified electrolytic manganese dioxide positive electrode active material; The amount of lithium carbonate used is 0.5wt%-1.5wt% of the mass of the electrolytic manganese dioxide positive electrode material; The amount of pure water used is 3wt%-8wt% of the mass of the electrolytic manganese dioxide positive electrode material; The ball milling temperature is 15°C-35°C; The ball milling time is 2h-8h; The soaking time is 12h-36h.

2. A lithium manganese battery, It is characterized in that The raw material comprises a modified electrolytic manganese dioxide positive electrode active material obtained by using the modification method of electrolytic manganese dioxide positive electrode active material according to claim 1.

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