A full-temperature range lithium-manganese dioxide soft-pack battery electrolyte and the resulting battery

Abstract

The present invention relates to the field of lithium battery manufacturing technology, and in particular to a full-temperature range lithium-manganese dioxide soft-pack battery electrolyte and the resulting battery. The weight percentage of the electrolyte is composed of 8-13wt% lithium salt, 80-89wt% solvent, 3-9wt% additive, and the sum of the weight percentages of each substance is 100%; the additive is a fluorine-containing additive, and the fluorine-containing additive is any three of propylene trifluorocarbonate, propylene trifluorocarbonate, fluoroethylene carbonate, hydrofluoroether, ethyl difluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate and phenyl trifluoroacetate. The present invention greatly improves the room temperature discharge performance, high and low temperature discharge performance and safety performance of the electrolyte through the synergistic effect of three fluorine-containing additives. The lithium-manganese dioxide soft-pack battery of the present invention has the characteristics of good room temperature discharge performance, good high and low temperature discharge performance and high safety, which further promotes the application of lithium-manganese dioxide soft-pack batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery manufacturing, and in particular to a full-temperature range lithium-manganese dioxide soft-pack battery electrolyte and a resulting battery. Background Art

[0002] As an important branch of lithium primary batteries, lithium-manganese dioxide soft-pack batteries are widely used in medicine, civil and other fields. Lithium-manganese dioxide soft-pack batteries are generally composed of positive electrodes, negative electrodes, diaphragms, electrolytes and aluminum-plastic film shells. The production steps include preparing bare cells, shelling bare cells, top sealing, side sealing, testing, liquid injection, vacuum pre-sealing, pre-discharging and trimming. Since the shell of lithium-manganese dioxide soft-pack batteries is made of aluminum-plastic film, in actual use scenarios, they are easily affected by the use environment, climate and external forces, and high and low temperature conditions or impacts will inevitably occur, which can easily lead to a serious decrease in the capacity of lithium-manganese dioxide soft-pack batteries or safety hazards. As the "blood" of the battery, the electrolyte plays a transportation role during the discharge process, and its characteristics have a direct impact on the overall performance of the battery. When there are physical and chemical property defects in the electrolyte, it will seriously affect the scope of application of lithium-manganese dioxide soft-pack batteries in many fields. In order to improve the problems caused by the electrolyte to the battery, people have conducted in-depth exploration of electrolyte additives. Electrolyte additives have the characteristics of low dosage and significant effects. How to select and proportion additives and effectively apply them in battery production has also become a problem that many battery companies need to solve. Electrolyte additives can be divided into fluorine-containing, boron-containing and nitrile types. Since the fluorine element has strong oxidizing properties, high flash point and flame retardancy, fluorine-containing additives have excellent electrochemical properties and can effectively enhance the stability and safety of the battery. However, the content of fluoroethylene carbonate is more critical. Excessive content will cause gas production inside the battery, which will cause the soft-pack battery to swell, and the steel-shell battery will destroy the explosion-proof membrane when the internal pressure is too high. Summary of the invention

[0003] In view of the above technical defects, the present invention provides a highly safe full-temperature range lithium-manganese dioxide soft-pack battery electrolyte, thereby obtaining a lithium-iron disulfide battery with high safety and excellent electrical performance.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a full-temperature range lithium-manganese dioxide soft-pack battery electrolyte, which is composed of 8-13wt% of lithium salt, 80-89wt% of solvent, and 3-9wt% of additives, and the sum of the weight percentages of each substance is 100%; the additive is a fluorine-containing additive, and the fluorine-containing additive is any three of trifluoropropylene carbonate, trifluoropropylene carbonate, fluoroethylene carbonate, hydrofluoroether, ethyl difluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate and phenyl trifluoroacetate.

[0005] Further: In the above-mentioned full-temperature range lithium-manganese dioxide soft-pack battery electrolyte, the three fluorine-containing additives are additives A, B, and C, additive A is fluoroethylene carbonate, additive B is hydrofluoroether, and additive C is ethyl trifluoroacetate. Additive A is 1 to 3 wt% of the electrolyte content, additive B is 1 to 3 wt% of the electrolyte content, and additive C is 1 to 3 wt% of the electrolyte content.

[0006] The lithium salt is at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium iodide, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium hexafluorophosphate and lithium perchlorate. Preferably, the lithium salt is a combination of lithium difluorooxalate borate and lithium perchlorate. The content of the lithium difluorooxalate borate is 7.0-12.0wt% of the electrolyte, and the content of the lithium perchlorate is 0.5-3.0wt% of the electrolyte.

[0007] The solvent is at least one of 1,3-dioxolane, 1,3-propylene sultone, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, vinyl sulfate, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether. Preferably, the solvent is a combination of 1,3-dioxolane, ethylene glycol dimethyl ether and 1,3-propylene sultone. The content of 1,3-dioxolane is 15-25wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 40-50wt% of the electrolyte, and the content of 1,3-propylene sultone is 20-30wt% of the electrolyte.

[0008] The present invention also discloses a lithium-manganese dioxide soft-pack battery, which comprises a bare battery core formed by winding a manganese dioxide positive electrode sheet, a lithium strip negative electrode sheet and a separator together, and applies the full-temperature range lithium-manganese dioxide soft-pack battery electrolyte of the present invention.

[0009] Compared with the prior art, the full-temperature range lithium-manganese dioxide soft-pack battery electrolyte of the present invention is composed of 8-13wt% of lithium salt, 80-89wt% of solvent, and 3-9wt% of additives, and the sum of the weight percentages of each substance is 100%; the additive is a fluorine-containing additive, and the fluorine-containing additive is any three fluorine-containing additives selected from trifluoropropylene carbonate, trifluoropropylene carbonate, fluoroethylene carbonate, hydrofluoroether, ethyl difluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate and phenyl trifluoroacetate. The present invention improves the electrolyte additives by introducing fluorine-containing additives with excellent electrochemical properties into the electrolyte in order to improve the electrochemical properties and safety performance of the battery. The electrolyte additive A fluoroethylene carbonate and the additive B hydrofluoroether of the present invention have the advantages of flame retardancy, high flash point and good high temperature stability in the electrolyte. Additive A and additive B, when used alone as electrolyte additives, often have unsatisfactory high temperature performance, and the content of additive A exceeds 3wt% of the electrolyte, which will cause gas production inside the battery. Additives A and B are mixed at a low content of 1 to 3 wt%, and the high temperature performance and safety performance of the battery are significantly improved while avoiding the disadvantages of additive A. The electrolyte additive C of the present invention, ethyl trifluoroacetate, has the functions of reducing electrolyte viscosity and improving wettability, and it has a low freezing point, which can improve the normal temperature and low temperature electrical properties of the battery. The content of additive C is limited to 1 to 3 wt% to ensure balanced high and low temperature performance of the battery. The present invention greatly improves the normal temperature discharge performance, high and low temperature discharge performance and safety performance of the battery electrolyte through the synergistic effect of three fluorine-containing additives. The lithium-manganese dioxide soft-pack battery of the present invention has the characteristics of good normal temperature discharge performance, good high and low temperature discharge performance and high safety, which further promotes the application of lithium-manganese dioxide soft-pack batteries. DETAILED DESCRIPTION

[0010] The main purpose of the present invention is to optimize the electrolyte by using fluorine-containing additives, improve the content of a single fluorine-containing additive, and adjust the single additive to multiple additives, which not only retains the advantages of a single fluorine-containing additive, but also greatly improves the normal temperature discharge performance, high and low temperature discharge performance and safety performance of the battery through the synergistic effect of multiple fluorine-containing additives. In addition, the problems of poor normal temperature discharge performance, high and low temperature discharge performance and safety performance of lithium-manganese dioxide soft-pack batteries are solved, and the application of lithium-manganese dioxide soft-pack batteries is further promoted. In order to enable technicians in this field to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples.

[0011] Example 1

[0012] Preparation of full-temperature range lithium-manganese dioxide soft-pack battery electrolyte: The electrolyte is obtained by dissolving lithium salt and additives in a mixed solvent. Lithium salt, lithium difluorooxalate borate content is 8wt% of the electrolyte, lithium perchlorate content is 2wt% of the electrolyte; solvent, 1,3-dioxolane content is 15wt% of the electrolyte, ethylene glycol dimethyl ether content is 50w% of the electrolyte, 1,3-propylene sultone content is 20wt% of the electrolyte; additives, additive A content is 1wt% of the electrolyte, additive B content is 3wt% of the electrolyte, additive C content is 1wt% of the electrolyte.

[0013] Preparation of CF552723 type lithium-manganese dioxide soft-pack battery: The manganese dioxide positive electrode sheet, the lithium belt negative electrode sheet and the separator are wound together to form a bare battery cell, and the top of the bare battery cell with the pole ear is sealed with a punched aluminum-plastic film shell, and one side of the battery cell is sealed. After partial packaging, a short-circuit test is performed, and then the electrolyte of this embodiment is injected and vacuum pre-sealed. After a pre-discharge, the battery is aged and trimmed, and then a second pre-discharge is performed to complete the assembly of the CF552723 type lithium-manganese dioxide soft-pack battery.

[0014] Example 2

[0015] Full temperature range lithium-manganese dioxide soft pack battery electrolyte: The electrolyte is obtained by dissolving lithium salt and additives in a mixed solvent. Lithium salt, lithium difluorooxalate borate content of the electrolyte is 8wt%, lithium perchlorate content of the electrolyte is 2wt%; solvent, 1,3-dioxolane content of the electrolyte is 15wt%, 130 content of ethylene glycol dimethyl ether is 50w% of the electrolyte, 1,3-propylene sultone content of the electrolyte is 20wt%; additives,

[0016] The content of additive A is 2wt% of the electrolyte, the content of additive B is 2wt% of the electrolyte, and the content of additive C is 1wt% of the electrolyte.

[0017] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0018] Example 3

[0019] 135 Full temperature range lithium-manganese dioxide soft pack battery electrolyte: Dissolve lithium salt and additives in a mixed solvent to obtain

[0020] Electrolyte. Lithium salt, lithium difluorooxalatoborate content of 8wt% of the electrolyte, lithium perchlorate content of 2wt% of the electrolyte; solvent, 1,3-dioxolane content of 15wt% of the electrolyte, ethylene glycol dimethyl ether content of 50w% of the electrolyte, 1,3-propylene sultone content of 20wt% of the electrolyte; additives,

[0021] The content of additive A is 3wt% of the electrolyte, the content of additive B is 1wt% of the electrolyte, and the content of additive C is 140wt% of the electrolyte.

[0022] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0023] Example 4

[0024] Full temperature range lithium-manganese dioxide soft pack battery electrolyte: obtained by dissolving lithium salt and additives in a mixed solvent

[0025] Electrolyte. Lithium salt, lithium difluorooxalatoborate content of the electrolyte is 8wt%, lithium perchlorate content of the electrolyte is 2wt%; solvent, 1,3-dioxolane content of the electrolyte is 15wt%, ethylene glycol dimethyl ether content of the electrolyte is 50w%, 1,3-propylene sultone content of the electrolyte is 20wt%; additives, additive A content of the electrolyte is 1wt%, additive B content of the electrolyte is 2wt%, additive C content of the electrolyte is 2wt%.

[0026] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0027] 150 Example 5

[0028] Full temperature range lithium-manganese dioxide soft pack battery electrolyte: The electrolyte is obtained by dissolving lithium salt and additives in a mixed solvent. Lithium salt, the content of lithium difluorooxalate borate is 8wt% of the electrolyte, the content of lithium perchlorate is 2wt% of the electrolyte; solvent, the content of 1,3-dioxolane is 15wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 50w% of the electrolyte, and the content of 1,3-propylene sultone is 20wt% of the electrolyte; additives, the content of 155 additive A is 2wt% of the electrolyte, the content of additive B is 1wt% of the electrolyte, and the content of additive C is 2wt% of the electrolyte.

[0029] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0030] Example 6

[0031] Full-temperature range lithium-manganese dioxide soft-pack battery electrolyte: The electrolyte is obtained by dissolving lithium salt and additives in a mixed solvent. Lithium salt, the content of lithium difluorooxalate borate is 8wt% of the electrolyte, the content of lithium perchlorate is 2wt% of the electrolyte; solvent, the content of 1,3-dioxolane is 15wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 50w% of the electrolyte, and the content of 1,3-propylene sultone is 20wt% of the electrolyte; additives, the content of additive A is 1wt% of the electrolyte, the content of additive B is 1wt% of the electrolyte, and the content of additive C is 3wt% of the electrolyte.

[0032] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0033] Comparative Example 1

[0034] Preparation of electrolyte: The electrolyte is obtained by dissolving lithium salt and additive in a mixed solvent. The content of lithium salt, lithium difluorooxalatoborate is 8wt% of the electrolyte, and the content of lithium perchlorate is 2wt% of the electrolyte; the content of solvent, 1,3-dioxolane is 15wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 50w% of the electrolyte, and the content of 1,3-propylene sultone is 22wt% of the electrolyte; the content of additive A is 3wt% of the electrolyte.

[0035] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0036] Comparative Example 2

[0037] Preparation of electrolyte: The electrolyte is obtained by dissolving lithium salt and additive in a mixed solvent. The content of lithium salt, lithium difluorooxalatoborate is 8wt% of the electrolyte, and the content of lithium perchlorate is 2wt% of the electrolyte; the content of solvent, 1,3-dioxolane is 15wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 50w% of the electrolyte, and the content of 1,3-propylene sultone is 22wt% of the electrolyte; the content of additive B is 3wt% of the electrolyte.

[0038] Comparative Example 3 of CF552723 lithium-manganese dioxide soft pack battery was assembled according to the method described in Example 1

[0039] Preparation of electrolyte: The electrolyte is obtained by dissolving lithium salt and additive in a mixed solvent. The content of lithium salt, lithium difluorooxalatoborate is 8wt% of the electrolyte, and the content of lithium perchlorate is 2wt% of the electrolyte; the content of solvent, 1,3-dioxolane is 15wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 50w% of the electrolyte, and the content of 1,3-propylene sultone is 22wt% of the electrolyte; the content of additive C is 3wt% of the electrolyte.

[0040] Assemble CF552723 lithium-manganese dioxide soft-pack batteries according to the method described in Example 1.

[0041] The difference between Comparative Examples 1 to 3 and Examples 1 to 6 is that Comparative Examples 1 to 3 all use a single additive, while Examples 1 to 6 use a mixture of three additives.

[0042] The CF552723 lithium-manganese dioxide soft-pack batteries in Examples 1 to 6 and Comparative Examples 1 to 3 were tested for electrical properties and safety performance. The test results are shown in Tables 1 to 4:

[0043] Table 1 Comparison of room temperature discharge performance of CF552723 lithium-manganese dioxide soft pack batteries

[0044]

[0045] Table 2 Comparison of high temperature discharge performance of CF552723 lithium-manganese dioxide soft pack batteries

[0046]

[0047]

[0048] Table 3 Comparison of low temperature discharge performance of CF552723 lithium-manganese dioxide soft pack batteries

[0049]

[0050] Table 4 Safety performance comparison of CF552723 lithium-manganese dioxide soft pack battery

[0051]

[0052]

[0053] By comparing the data of Examples 1 to 6 and Comparative Examples 1 to 3 in Tables 1 to 4, it is found that the CF552723 lithium-manganese dioxide soft-pack battery using the safe full-temperature electrolyte of the present invention improves the room temperature discharge performance, high and low temperature discharge performance and safety performance, indicating that the safe full-temperature electrolyte of the present invention can effectively improve the electrical properties and safety performance of the lithium-manganese dioxide soft-pack battery.

[0054] The embodiments described above are only preferred implementations of the present invention and are not intended to limit the scope of the present invention. Any obvious modifications and substitutions made without departing from the concept of the present invention are intended to fall within the protection scope of the present invention.

Claims

1. A full-temperature range lithium-manganese dioxide soft-pack battery electrolyte, which is composed of 8-13wt% of lithium salt, 80-89wt% of solvent, and 3-9wt% of additives, and the sum of the weight percentages of each substance is 100%; the additive is a fluorine-containing additive, and the fluorine-containing additive is any three of trifluoropropylene carbonate, trifluoropropylene carbonate, fluoroethylene carbonate, hydrofluoroether, ethyl difluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate and phenyl trifluoroacetate.

2. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 1, characterized in that: The three fluorine-containing additives are additives A, B and C, additive A is fluoroethylene carbonate, additive B is hydrofluoroether, and additive C is ethyl trifluoroacetate.

3. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 2, characterized in that: The additive A accounts for 1 to 3 wt % of the electrolyte content, the additive B accounts for 1 to 3 wt % of the electrolyte content, and the additive C accounts for 1 to 3 wt % of the electrolyte content.

4. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 3, characterized in that: The lithium salt is at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium iodide, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium hexafluorophosphate and lithium perchlorate.

5. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 4, characterized in that: The lithium salt is a combination of lithium difluorooxalatoborate and lithium perchlorate.

6. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 5, characterized in that: The content of the lithium difluorooxalatoborate is 7.0-12.0 wt % of the electrolyte, and the content of the lithium perchlorate is 0.5-3.0 wt % of the electrolyte.

7. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 6, characterized in that: The solvent is at least one of 1,3-dioxolane, 1,3-propylene sultone, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, vinyl sulfate, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.

8. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 7, characterized in that: The solvent is a combination of 1,3-dioxolane, ethylene glycol dimethyl ether and 1,3-propylene sultone.

9. The full-temperature range lithium-manganese dioxide soft-pack battery electrolyte according to claim 7, characterized in that: The content of 1,3-dioxolane is 15-25wt% of the electrolyte, the content of ethylene glycol dimethyl ether is 40-50wt% of the electrolyte, and the content of 1,3-propylene sultone is 20-30wt% of the electrolyte.

10. A lithium-manganese dioxide soft pack battery, characterized in that: It comprises a bare battery cell formed by winding a manganese dioxide positive electrode sheet, a lithium strip negative electrode sheet and a separator together, and a full-temperature range lithium-manganese dioxide soft-pack battery electrolyte as described in any one of claims 1-9.

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