Lithium-manganese battery electrolyte as well as preparation method and application thereof

Abstract

The invention provides a lithium-manganese battery electrolyte and a preparation method and application thereof, and belongs to the technical field of battery electrolytes.The lithium-manganese battery electrolyte comprises a lithium salt, an organic solvent and an additive, and the additive comprises one or more of an organic silicon source, toluenesulfonyl isocyanate, 1, 3-propane sultone, 1, 4-butane sultone and triphenyl phosphate. According to the invention, the long-term storage stability of the electrolyte and the compatibility with the lithium elementary substance are improved, a compact SEI film is formed on the surfaces of a positive electrode and a negative electrode, side reactions during storage are reduced, the long-term storage performance of the battery is improved, the self-discharge rate of the battery is reduced, and the electrolyte is more matched with the system characteristics and the use environment of the lithium-manganese battery; the storage life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrolytes, and in particular to a lithium manganese battery electrolyte and a preparation method and application thereof. Background Art

[0002] Lithium-manganese batteries are used in scenarios that require long-term storage, maintenance-free, or high energy density due to their high energy density, low self-discharge rate, and safety. Since the batteries in such scenarios need to be stored silently for a long time, the life of a platform carrying lithium-manganese batteries is generally 10 years, while the storage life of lithium-manganese batteries is generally 5 to 7 years, so the batteries need to be replaced every 5 years. This increases maintenance costs and battery replacement time. To achieve the goal of not replacing batteries during the entire mission cycle of the platform, the storage life of the batteries needs to be increased to 10 years or even longer, which places higher requirements on the storage performance of lithium-manganese batteries.

[0003] The electrolyte is an important component of the battery. It is responsible for transporting ions between the positive and negative electrodes through the battery. It has an important impact on the battery's capacity, operating temperature range, storage performance and safety performance. During storage, the positive and negative electrodes of lithium-ion batteries are immersed in the electrolyte. Thermodynamically unstable substances are prone to side reactions, such as the dissolution of active substances, corrosion of current collectors and electrode / electrolyte interface reactions. As the storage time increases, the impact of these reactions on the battery continues to increase, ultimately affecting the battery life and even causing safety issues. At present, the most widely used commercial electrolyte system is a mixed carbonate solution of lithium hexafluorophosphate. This system electrolyte is mostly used in lithium-ion batteries, and its compatibility with lithium in lithium-manganese batteries needs to be improved. In particular, the side reactions during long-term storage still need to be further reduced to meet the long-term storage requirements of lithium-manganese batteries. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present application provides a lithium manganese battery electrolyte and its preparation method and application, aiming to solve the technical problems that thermodynamically unstable substances in the existing lithium manganese battery electrolyte are prone to side reactions during long-term storage and have insufficient compatibility with lithium element.

[0005] In a first aspect, an embodiment of the present application provides a lithium manganese battery electrolyte, comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises one or more of an organic silicon source, toluenesulfonyl isocyanate, 1,3-propane sultone, 1,4-butane sultone, and triphenyl phosphite, and the additive accounts for 2% to 5% of the total mass of the electrolyte.

[0006] In the technical solution of the embodiment of the present application, adding an organic silicon source to the electrolyte can reduce the loss of the electrolyte during the charging and discharging process, reduce the change of the electrolyte and the increase of the internal resistance, reduce the volatilization of the electrolyte, and maintain the stability of the electrolyte; 1,3-propane sultone can inhibit the side reactions on the electrolyte surface, reduce the dissolution of metal ions, and increase the cycle life and storage stability of the battery; toluenesulfonyl isocyanate can form a stable solid electrolyte interface (SEI) film on the metal lithium negative electrode, improve the compatibility between the metal lithium negative electrode and the electrolyte, and can also react with trace amounts of water, hydroxyl groups and F- ions in the electrolyte, thereby improving the stability of the electrolyte and improving the cycle performance and storage performance of the electrolyte; 1,4-butane sultone can improve the high temperature resistance of the battery and prevent flatulence.

[0007] The additive of the present application can improve the long-term storage stability of the electrolyte and its compatibility with lithium, form a denser passivation film on the surface of the negative electrode, reduce the occurrence of side reactions during storage, improve the long-term storage performance of the battery, and reduce the self-discharge rate of the battery.

[0008] Preferably, the additive comprises an organosilicon source, 1,3-propane sultone and toluenesulfonyl isocyanate, and the mass ratio of the organosilicon source, 1,3-propane sultone and toluenesulfonyl isocyanate is 6:(2-3):(1-2).

[0009] Preferably, the organic silicon source includes one or more of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0010] Preferably, the additive comprises toluenesulfonyl isocyanate, 1,4-butane sultone and triphenyl phosphite, and the mass ratio of toluenesulfonyl isocyanate, 1,4-butane sultone and triphenyl phosphite is 6:(1-3):(1-3).

[0011] Preferably, the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide.

[0012] In the technical solution of the embodiment of the present application, the electrolyte salt selected in the present application has high stability itself, and has high chemical and electrochemical stability with the lithium negative electrode, current collector, active material, conductive agent, etc.

[0013] Preferably, the concentration of the lithium salt in the organic solvent is 1-2 mol / L.

[0014] Preferably, the organic solvent includes one or more of dimethyl carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, tetrahydrofuran and sulfolane.

[0015] In the technical solution of the embodiment of the present application, the mixed solvent prepared by the above-mentioned organic solvent has a high boiling point, a high flash point, a large dielectric constant and good stability, and can form a dense double SEI film on the surface of the electrode material, which can better cover the surface of the negative electrode material, and effectively reduce the reduction and decomposition of the contact surface between the electrolyte and the negative electrode material of the battery during long-term storage, thereby increasing the storage stability of the battery and reducing the self-discharge rate of the battery.

[0016] In a second aspect, an embodiment of the present application provides a method for preparing a lithium manganese battery electrolyte, comprising the following steps: adding a lithium salt to an organic solvent and mixing the mixture evenly, adding an additive thereto, stirring and dispersing the mixture under heating conditions, and obtaining an electrolyte after cooling.

[0017] Preferably, the heating temperature is 50-60°C.

[0018] In a third aspect, an embodiment of the present application provides a lithium manganese battery, comprising the above-mentioned lithium manganese battery electrolyte.

[0019] Different from the existing technical solutions, the beneficial effects of this application include: The present application improves the long-term storage stability of the electrolyte and its compatibility with lithium, forms a denser SEI film on the surface of the positive and negative electrodes, reduces the occurrence of side reactions during storage, improves the long-term storage performance of the battery, reduces the self-discharge rate of the battery, and better matches the electrolyte of the lithium manganese battery system characteristics and the use environment, extending the storage life of the battery. Under the condition of long-term storage, the present application can maintain stable performance, with few battery side reactions and an annual self-discharge rate of less than 1%. After 10 years of long-term storage, the battery voltage, internal resistance, etc. are normal, and the capacity can be maintained at more than 90%.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 The discharge curves of the lithium manganese battery prepared with the electrolyte in Example 1 before and after high temperature storage. DETAILED DESCRIPTION

[0023] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0025] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0026] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0028] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0029] During storage, the positive and negative electrodes of lithium-ion batteries are immersed in electrolytes. Thermodynamically unstable substances are prone to side reactions, such as dissolution of active substances, corrosion of current collectors, and electrode / electrolyte interface reactions. As storage time increases, the impact of these reactions on the battery continues to increase, ultimately affecting battery life and even causing safety issues. Currently, the most widely used commercial electrolyte system is a mixed carbonate solution of lithium hexafluorophosphate. This system electrolyte is mostly used in lithium-ion batteries, and its compatibility with lithium in lithium-manganese batteries needs to be improved, especially during long-term storage. The side reactions still need to be further reduced to meet the long-term storage requirements of lithium-manganese batteries.

[0030] In order to solve the technical problems that thermodynamically unstable substances in existing lithium-manganese battery electrolytes are prone to side reactions and have insufficient compatibility with lithium elements during long-term storage, the present application provides a lithium-manganese battery electrolyte and a preparation method and application thereof, wherein, through the selection of lithium salts, solvents and additives, stable performance can be maintained under long-term storage conditions, battery side reactions are few, and the annual self-discharge rate is less than 1%. After 10 years of long-term storage, the battery voltage, internal resistance, etc. are normal, and the capacity can be maintained at more than 90%.

[0031] In a first aspect, an embodiment of the present application provides a lithium manganese battery electrolyte, comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises one or more of an organic silicon source, toluenesulfonyl isocyanate, 1,3-propane sultone, 1,4-butane sultone, and triphenyl phosphite, and the additive accounts for 2% to 5% of the total mass of the electrolyte.

[0032] In the technical solution of the embodiment of the present application, adding an organic silicon source to the electrolyte can reduce the loss of the electrolyte during the charging and discharging process, reduce the change of the electrolyte and the increase of the internal resistance, reduce the volatilization of the electrolyte, and maintain the stability of the electrolyte; 1,3-propane sultone can inhibit the side reactions on the electrolyte surface, reduce the dissolution of metal ions, and increase the cycle life and storage stability of the battery; toluenesulfonyl isocyanate can form a stable solid electrolyte interface (SEI) film on the metal lithium negative electrode, improve the compatibility between the metal lithium negative electrode and the electrolyte, and can also react with trace amounts of water, hydroxyl groups and F- ions in the electrolyte, thereby improving the stability of the electrolyte and improving the cycle performance and storage performance of the electrolyte; 1,4-butane sultone can improve the high temperature resistance of the battery and prevent flatulence.

[0033] The additive of the present application can improve the long-term storage stability of the electrolyte and its compatibility with lithium, form a denser passivation film on the surface of the negative electrode, reduce the occurrence of side reactions during storage, improve the long-term storage performance of the battery, and reduce the self-discharge rate of the battery.

[0034] Preferably, the additive comprises an organosilicon source, 1,3-propane sultone and toluenesulfonyl isocyanate, and the mass ratio of the organosilicon source, 1,3-propane sultone and toluenesulfonyl isocyanate is 6:(2-3):(1-2).

[0035] Preferably, the organic silicon source includes one or more of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0036] Preferably, the additive comprises toluenesulfonyl isocyanate, 1,4-butane sultone and triphenyl phosphite, and the mass ratio of toluenesulfonyl isocyanate, 1,4-butane sultone and triphenyl phosphite is 6:(1-3):(1-3).

[0037] Preferably, the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide.

[0038] In the technical solution of the embodiment of the present application, the electrolyte salt selected in the present application has high stability itself, and has high chemical and electrochemical stability with the lithium negative electrode, current collector, active material, conductive agent, etc.

[0039] Preferably, the concentration of the lithium salt in the organic solvent is 1-2 mol / L.

[0040] Preferably, the organic solvent includes one or more of dimethyl carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, tetrahydrofuran and sulfolane.

[0041] In the technical solution of the embodiment of the present application, the mixed solvent prepared by the above-mentioned organic solvent has a high boiling point, a high flash point, a large dielectric constant and good stability, and can form a dense double SEI film on the surface of the electrode material, which can better cover the surface of the negative electrode material, and effectively reduce the reduction and decomposition of the contact surface between the electrolyte and the negative electrode material of the battery during long-term storage, thereby increasing the storage stability of the battery and reducing the self-discharge rate of the battery.

[0042] In a second aspect, an embodiment of the present application provides a method for preparing a lithium manganese battery electrolyte, comprising the following steps: adding a lithium salt to an organic solvent and mixing the mixture evenly, adding an additive thereto, stirring and dispersing the mixture under heating conditions, and obtaining an electrolyte after cooling.

[0043] Preferably, the heating temperature is 50-60°C.

[0044] In a third aspect, an embodiment of the present application provides a lithium manganese battery, comprising the above-mentioned lithium manganese battery electrolyte.

[0045] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0046] 1. Preparation method Example 1 The preparation method of the lithium manganese battery electrolyte in Example 1 comprises the following steps: at room temperature, in a glove box, dissolving 1 mol of lithium hexafluorophosphate into 1 L of an organic solvent composed of dimethyl carbonate and ethyl methyl carbonate in a ratio of 1:1, taking 96 g of the above solution, adding 2.4 g of methyl orthosilicate, 1.2 g of 1,3-propane sultone and 0.4 g of tosyl isocyanate, and stirring thoroughly to prepare an electrolyte.

[0047] Example 2 The preparation method of the battery electrolyte in Example 2 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate is dissolved in 1 L of an organic solvent composed of dimethyl carbonate, ethyl methyl carbonate, and vinylene carbonate in a ratio of 5:4:1, 96 g of the above solution is taken, and then 2.4 g of methyl orthosilicate, 0.8 g of 1,3-propane sultone, and 0.8 g of tosyl isocyanate are added. After sufficient stirring, an electrolyte is prepared.

[0048] Example 3 The preparation method of the battery electrolyte in Example 3 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate and 0.2 mol of lithium perchlorate are dissolved in 1 L of an organic solvent composed of dimethyl carbonate and ethyl methyl carbonate in a ratio of 1:1, 96 g of the above solution is taken, and then 2.4 g of toluenesulfonyl isocyanate, 0.8 g of 1,4-butane sultone and 0.8 g of triphenyl phosphite are added. After sufficient stirring, an electrolyte is prepared.

[0049] Example 4 The preparation method of the battery electrolyte in Example 4 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate and 0.2 mol of lithium perchlorate are dissolved in 1 L of an organic solvent composed of dimethyl carbonate, ethyl methyl carbonate, and vinylene carbonate in a ratio of 5:4:1, 96 g of the above solution is taken, and then 2.4 g of toluenesulfonyl isocyanate, 1.2 g of 1,4-butane sultone, and 0.4 g of triphenyl phosphite are added. After sufficient stirring, an electrolyte is prepared.

[0050] Example 5 The preparation method of the battery electrolyte in Example 6 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate is dissolved in 1 L of an organic solvent composed of dimethyl carbonate and ethyl methyl carbonate in a ratio of 1:1, 96 g of the above solution is taken, and then 2.4 g of toluenesulfonyl isocyanate, 0.4 g of 1,4-butane sultone and 1.2 g of triphenyl phosphite are added. After sufficient stirring, an electrolyte is prepared.

[0051] Comparative Example 1 The preparation method of the battery electrolyte in Comparative Example 1 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate and 0.2 mol of lithium difluorooxalatoborate are dissolved in 1 L of an organic solvent composed of dimethyl carbonate, ethyl methyl carbonate and vinylene carbonate in a ratio of 5:4:1.

[0052] Comparative Example 2 The preparation method of the battery electrolyte in Comparative Example 2 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate is dissolved in 1 L of an organic solvent composed of dimethyl carbonate and ethyl methyl carbonate in a ratio of 1:1. After sufficient stirring, an electrolyte is prepared.

[0053] Comparative Example 3 The preparation method of the battery electrolyte in Comparative Example 3 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate and 0.2 mol of lithium perchlorate are dissolved in 1 L of an organic solvent consisting of dimethyl carbonate and ethyl methyl carbonate in a ratio of 1:1. After sufficient stirring, 98 g of the above solution is taken, and 1.2 g of 1,3-propane sultone and 0.8 g of 1,4-butane sultone are added. After sufficient stirring, an electrolyte is prepared.

[0054] Comparative Example 4 The preparation method of the battery electrolyte in Comparative Example 4 is different from that in Example 1 in that 1 mol of lithium hexafluorophosphate is dissolved in 1 L of an organic solvent consisting of dimethyl carbonate, ethyl methyl carbonate, and vinylene carbonate in a ratio of 5:4:1. After sufficient stirring, 98 g of the above solution is taken, and 2 g of methyl orthosilicate is added. After sufficient stirring, an electrolyte is prepared.

[0055] 2. Test Method A mixture of manganese dioxide, expanded graphite and Ketjen black is used as the positive electrode of the battery, a lithium ribbon is used as the negative electrode of the battery, and the diaphragm is a polypropylene ceramic diaphragm. The electrolyte is injected to make a soft-pack lithium-manganese primary battery.

[0056] 1. The obtained lithium manganese primary battery is subjected to storage performance test, and the test method is as follows: Accelerated storage test 1) Acceleration model Referring to GJB 736.8, using the modified Arrhenius reaction rate theory, the acceleration coefficient and the reaction rate temperature coefficient have a reaction equation:

[0057] Where: τ - acceleration coefficient; r—reaction rate temperature coefficient, take 2.3; T1—accelerated test absolute temperature, in K; T0—relative absolute temperature, in K; A—temperature change corresponding to the temperature coefficient of reaction rate, taken as 10K; Right now:

[0058] The accelerated test time can be calculated according to the following formula.

[0059]

[0060] Where: t1—time required for accelerated test at absolute temperature T1 (days); t0 - Storage time (days) at relative absolute temperature T0.

[0061] It is calculated that 73 days of storage at 72°C is equivalent to 10 years of storage at 25°C.

[0062] 2) Accelerated stress selection T1 is 72℃, which is 342.15K.

[0063] 3) Test methods Before the test, check the appearance and open circuit voltage of the battery, put the test sample into the temperature box, and raise the temperature to 72℃±2℃ for storage.

[0064] When the storage time is up, restore to room temperature for 2 hours, first check the appearance and open circuit voltage, then transfer the test sample to a low temperature box and conduct a discharge capacity test at a temperature of (0℃±2℃).

[0065] 2. The obtained lithium manganese primary battery is subjected to a storage life test, and the test method is as follows: 1) Before the test, check the appearance, open circuit voltage and internal resistance of the battery, and store the test sample in an environment of 25℃±3℃; 2) Check the appearance, open circuit voltage and internal resistance of the battery every year, and remove some batteries for normal temperature capacity test.

[0066] III. Analysis of test results of various embodiments and comparative examples (1) Storage performance tests were conducted on Examples 1-3 and Comparative Examples 1-2. The test results are shown in Table 1 below.

[0067] Table 1 Accelerated storage test results of various embodiments and comparative examples

[0068] As can be seen from Table 1, the internal resistance and differential pressure of the lithium manganese battery prepared by using the electrolyte in Examples 1 to 5 did not change much before and after storage, and the lithium manganese battery was in good condition, indicating that the lithium manganese battery prepared by using the electrolyte in Examples 1 to 5 had good storage stability. In Comparative Examples 1 to 4, after the accelerated storage test, the internal resistance and differential pressure changed greatly, and the battery also bulged, indicating that the additives of the present application are more helpful in improving the long-term storage stability of the lithium manganese battery and extending the storage life of the battery when used in multiple combinations.

[0069] Figure 1 Comparing the discharge curves of the lithium manganese battery prepared with the electrolyte in Example 2 before and after high-temperature accelerated storage (equivalent to 7 years of storage at room temperature), it can be seen that after storage, the battery capacity retention rate is 93%, which is maintained at a relatively high level.

[0070] (2) A storage life test was conducted on Examples 1 to 5 and Comparative Examples 1 to 4. The test results are shown in Table 2 below.

[0071] Table 2 Storage life experimental data of lithium manganese battery prepared from electrolyte in Example 5

[0072] It can be seen from Table 2 that the lithium manganese battery prepared using the electrolyte in the present application can still maintain a relatively high battery capacity after long-term storage.

[0073] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium manganese battery electrolyte, characterized in that: The electrolyte comprises a lithium salt, an organic solvent and an additive, wherein the additive comprises one or more of an organic silicon source, toluenesulfonyl isocyanate, 1,3-propane sultone, 1,4-butane sultone and triphenyl phosphite, and the additive accounts for 2% to 5% of the total mass of the electrolyte.

2. The lithium manganese battery electrolyte according to claim 1, characterized in that: The additive comprises an organic silicon source, 1,3-propane sultone and toluene sulfonyl isocyanate, and the mass ratio of the organic silicon source, 1,3-propane sultone and toluene sulfonyl isocyanate is 6:(2-3):(1-2).

3. The lithium manganese battery electrolyte according to claim 1, characterized in that: The organic silicon source includes one or more of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

4. The lithium manganese battery electrolyte according to claim 1, characterized in that: The additive comprises toluenesulfonyl isocyanate, 1,4-butane sultone and triphenyl phosphite, and the mass ratio of the toluenesulfonyl isocyanate, 1,4-butane sultone and triphenyl phosphite is 6:(1-3):(1-3).

5. The lithium manganese battery electrolyte according to claim 1, characterized in that: The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide.

6. The lithium manganese battery electrolyte according to claim 1, characterized in that: The concentration of the lithium salt in the organic solvent is 1-2 mol / L.

7. The lithium manganese battery electrolyte according to claim 1, characterized in that: The organic solvent includes one or more of dimethyl carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, tetrahydrofuran and sulfolane.

8. The method for preparing a lithium manganese battery electrolyte according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: adding the lithium salt into an organic solvent and mixing evenly, adding an additive thereto, stirring and dispersing under heating conditions, and obtaining an electrolyte after cooling.

9. The method for preparing a lithium manganese battery electrolyte according to claim 8, characterized in that: The heating temperature is 50-60°C.

10. A lithium manganese battery, characterized in that: A lithium manganese battery electrolyte comprising the electrolyte of any one of claims 1 to 6.

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