Electrolyte suitable for lithium primary battery and lithium primary battery
By optimizing the combination of electrolyte lithium salt and additives in lithium primary batteries, a low-impedance SEI film and passivation film are formed, solving the problem of performance degradation of lithium primary batteries at extreme temperatures and achieving improved high and low temperature performance and enhanced safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NINGDE GUOTAI HUARONG NEW MATERIAL CO LTD
- Filing Date
- 2024-12-12
- Publication Date
- 2026-06-19
AI Technical Summary
Existing lithium primary batteries exhibit performance degradation under extreme temperature environments, particularly at low temperatures where discharge capacity weakens and internal resistance increases. At high temperatures, they are prone to leakage and pose safety hazards. Furthermore, the commonly used solvent DME is restricted by the European Union, and DOL is prone to polymerization at high temperatures, limiting their applications.
Lithium salts such as lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, and lithium difluorophosphate, along with organic solvents such as 1-fluoro-2-(2-fluoroethoxy)ethane, and additives such as lithium difluorophosphate and 1,3-propane sulpholol, are used to form a low-impedance SEI film and a passivation film, thereby improving conductivity and high-temperature stability.
Maintaining good performance under extreme temperatures, suppressing high-temperature gas expansion, improving discharge performance, and expanding the application range of lithium primary batteries.
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium primary battery technology, and specifically to an electrolyte suitable for lithium primary batteries and a lithium primary battery. Background Technology
[0002] With the development of science and technology, lithium primary batteries have become a key supporting product and an important technological foundation for weapons and electronic equipment, and are one of the important factors restricting their development. Countries around the world attach great importance to the research and development of lithium primary batteries. In existing weapons and electronic equipment, a wide variety of lithium primary batteries are used. Based on the different cathode materials, they are mainly classified into lithium sulfur dioxide batteries, lithium thionyl chloride batteries, lithium manganese dioxide batteries, lithium iron disulfide batteries, and lithium carbon fluoride batteries, etc.
[0003] Lithium-manganese dioxide (Li / MnO2) batteries were the first commercially available lithium / solid cathode system battery and are also the most widely used type of lithium primary battery, with an actual specific energy exceeding 260–400 Wh / kg. These batteries have a rated voltage greater than 3V, an operating voltage plateau of around 2.7V, an operating temperature range of -40–75℃, and a storage life of over 10 years. Lithium-manganese dioxide batteries use manganese dioxide as the cathode and typically employ a mixed organic solvent containing lithium perchlorate as the electrolyte. Their structural types include button, cylindrical, prismatic, and pouch cells.
[0004] Wide-temperature lithium primary battery technology is a novel battery technology developed to address the performance degradation of lithium primary batteries under extreme temperature environments. Lithium primary batteries, a crucial energy technology widely used in mobile electronic devices and military applications, are significantly affected by temperature. Conventional lithium primary batteries experience decreased discharge capacity and increased internal resistance at low temperatures, while high temperatures can easily lead to battery leakage and safety hazards. Therefore, the development of wide-temperature lithium primary battery technology has become crucial for improving the reliability and safety of lithium primary batteries under extreme temperature conditions.
[0005] The core idea of wide-temperature lithium primary battery technology lies in finding a novel electrolyte and electrolyte system that allows lithium primary batteries to maintain good performance under extreme low and high temperature environments. At low temperatures, by increasing additives and improving the solvent composition in the electrolyte, the viscosity and conductivity of the battery can be effectively improved, reducing the increase in internal resistance. Simultaneously, high-temperature additives can improve the battery's heat resistance at high temperatures, preventing battery leakage and safety accidents.
[0006] Commonly used organic solvents for lithium primary batteries include propylene carbonate, dimethyl ethylene glycol (DME), and 1,3-dioxolane (DOL). Among them, DME is a restricted substance under EU regulations, which will limit its future application and restrict its low-temperature performance. DOL has a significant effect on improving low-temperature performance, but it is prone to catalytic ring-opening polymerization and agglomeration under various conditions such as high temperature and Lewis acids, which greatly limits its application in the field of wide-temperature lithium primary batteries.
[0007] Therefore, there is an urgent need to provide a lithium primary battery electrolyte to solve the above problems, so that lithium primary batteries can be better promoted and applied. Summary of the Invention
[0008] The purpose of this invention is to provide a wide-temperature electrolyte suitable for lithium primary batteries; this electrolyte not only has excellent discharge performance at low temperatures, but also suppresses gas expansion of lithium primary batteries under high-temperature conditions, thereby improving high-temperature discharge performance.
[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0010] The first aspect of this invention provides an electrolyte suitable for lithium primary batteries, comprising an electrolyte lithium salt, additives, and an organic solvent.
[0011] The electrolyte lithium salt is any one or more of lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorosulfonylimide.
[0012] The organic solvents include propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (CAS: 373-21-7);
[0013] The additive is one or more combinations of lithium difluorophosphate, 1,3-propanesulfonyl lactone, tetraethylenesilane, succinic anhydride, and citrate anhydride.
[0014] The addition of 1-fluoro-2-(2-fluoroethoxy)ethane not only improves conductivity but also has low viscosity at low temperatures, greatly enhancing the low-temperature performance of the battery.
[0015] According to some specific embodiments, the molar concentration of the electrolyte lithium salt is 0.01 mol / L to 2 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, etc. Further, the molar concentration of the electrolyte lithium salt is 0.5 to 1.5 mol / L. Even further, the molar concentration of the electrolyte lithium salt is 0.8 mol / L to 1.5 mol / L.
[0016] According to some specific implementation methods, the electrolyte lithium salt is lithium bis(fluorosulfonyl)imide lithium, lithium bis(trifluoromethylsulfonyl)imide lithium, etc., which do not have strong oxidizing properties and have higher ionic conductivity compared with lithium perchlorate.
[0017] According to some specific embodiments, the organic solvent accounts for 5% to 95% of the total mass of the electrolyte. Further, the organic solvent accounts for 50% to 95% of the total mass of the electrolyte, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc.
[0018] According to some specific embodiments, the organic solvent does not contain DME and DOL, solvents commonly used in lithium primary batteries.
[0019] According to some specific embodiments, the organic solvent is composed of propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane.
[0020] According to some specific embodiments, the mass ratio of propylene carbonate to 1-fluoro-2-(2-fluoroethoxy)ethane is 0.5 to 2:1, for example, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, or 2:1. Further, the mass ratio of propylene carbonate to 1-fluoro-2-(2-fluoroethoxy)ethane is 1 to 1.5:1.
[0021] According to some specific embodiments, the additive also includes 1,3-dioxane and / or lithium hexafluorophosphate.
[0022] According to some specific embodiments, the total mass of the additives accounts for 0.05% to 15% of the total mass of the electrolyte, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, etc. 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7% 4.8%, 4.9%, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7. 6%, 7.7%, 7.8%, 7.9%, 8%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10%, 11%, 12%, 13%, 14%, 15%. Further, the total mass of the additives accounts for 0.05% to 10% of the total mass of the electrolyte.
[0023] According to some specific embodiments, the additive is one or more selected from 1,3-propanesulfonyl lactone, tetraethylenesilane, succinic anhydride, citrate anhydride, 1,3-dioxane, and lithium hexafluorophosphate, as well as lithium difluorophosphate, wherein the mass of the lithium difluorophosphate accounts for 0.1% to 5% of the total mass of the electrolyte; for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, and 1.4%. 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5%, etc.
[0024] Lithium difluorophosphate can form a low-resistance SEI film on the negative electrode, improving the battery's high and low temperature performance. 1,3-propanesulfonyl lactone, tetraethylenesilane, succinic anhydride, and citrate anhydride can participate in the passivation film formation process on the manganese dioxide positive electrode material, improving the passivation film quality and enhancing the battery's high-temperature performance. The addition of lithium hexafluorophosphate allows it to react with aluminum foil on the positive electrode current collector of a cylindrical lithium-manganese primary battery, forming a passivation film on its surface. This prevents corrosion of the aluminum foil by other corrosive substances, thus avoiding battery failure caused by low voltage and high internal resistance. The addition of 1,3-dioxane can form a film on the positive electrode surface, inhibiting the oxidative decomposition of the solvent.
[0025] A second aspect of the present invention provides a lithium primary battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the aforementioned electrolyte.
[0026] According to some specific embodiments, the active material of the positive electrode is manganese dioxide, and the active material of the negative electrode is lithium metal.
[0027] According to some specific embodiments, the lithium primary battery is in the shape of a button, cylindrical, square, or pouch cell.
[0028] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:
[0029] This invention, through the selection and combination of the above-mentioned electrolyte lithium salt, additives and solvents, can be applied in lithium primary batteries. It can not only ensure that the battery does not generate gas during long-term high-temperature storage, but also improve the high and low temperature discharge performance of the battery. Therefore, it has broad application prospects in future wide-temperature lithium manganese primary batteries. Detailed Implementation
[0030] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.
[0031] Unless otherwise specified, the reagents, instruments, etc. used in the following examples and comparative examples are all commercially available products commonly used in the art, or can be prepared using conventional methods in the art. In this invention, unless otherwise specified, all contents are mass contents, "%" is mass percentage, and parts are parts by mass.
[0032] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the ranges, the endpoint values of the ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The terms "optional" and "discretionary" mean that they may or may not be included (or may or may not be present).
[0033] To provide a more intuitive comparison of the electrolyte's performance, the batteries used in the following comparative examples and embodiments are lithium manganese soft-pack CP264260 lithium manganese primary batteries.
[0034] The thickness of the soft-pack CP264260 lithium manganese primary battery used in the examples and comparative examples is 2.6 mm.
[0035] Comparative Example 1
[0036] The organic solvents are propylene carbonate and ethylene glycol dimethyl ether (mass ratio of 30:70); the electrolyte lithium salt is lithium trifluoromethanesulfonate with a concentration of 1 mol / L, and no other additives are added.
[0037] Comparative Example 2
[0038] The organic solvents are propylene carbonate, ethylene glycol dimethyl ether, and 1,3-dioxolane (in a mass ratio of 20:30:50); the electrolyte lithium salt is lithium perchlorate with a concentration of 1.1 mol / L.
[0039] Comparative Example 3
[0040] The organic solvents are propylene carbonate, ethylene glycol dimethyl ether, and 1,3-dioxolane (in a mass ratio of 20:30:50); the electrolyte lithium salt is lithium perchlorate with a concentration of 1.1 mol / L; and the additive is 1% citrate anhydride.
[0041] Comparative Example 4
[0042] The organic solvent is propylene carbonate, ethylene glycol dimethyl ether, and 1,3-dioxolane (in a mass ratio of 20:30:50); the electrolyte lithium salt is lithium perchlorate with a concentration of 1.1 mol / L; and the additive is 1% lithium hexafluorophosphate.
[0043] Example 1
[0044] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium perchlorate; and the additive is 0.5% lithium difluorophosphate.
[0045] Example 2
[0046] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide, and the additive is 0.5% lithium difluorophosphate.
[0047] Example 3
[0048] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide; the additives are 0.5% lithium difluorophosphate and 1% PS (1,3-propanesulfonyl lactone).
[0049] Example 4
[0050] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide; the additives are 0.5% lithium difluorophosphate and 2% PS.
[0051] Example 5
[0052] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide; the additives are 0.5% lithium difluorophosphate, 1% PS and 1% citrate anhydride.
[0053] Example 6
[0054] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide; the additives are 0.5% lithium difluorophosphate, 1% PS, 1% citrate anhydride and 0.3% 1,3-dioxane.
[0055] Example 7
[0056] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 50:50); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide; the additives are 0.5% lithium difluorophosphate, 1% PS, 1% citrate anhydride and 0.3% 1,3-dioxane.
[0057] Example 8
[0058] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1 mol / L lithium difluorosulfonylimide; the additives are 1% lithium difluorophosphate, 1% tetraethylenesilane, 1% succinic anhydride and 0.3% 1,3-dioxane.
[0059] Example 9
[0060] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 60:40); the electrolyte lithium salt is 1.1 mol / L lithium difluorosulfonylimide; the additives are 1% lithium difluorophosphate, 1% PS, 1% tetraethylenesilane, 1% succinic anhydride and 0.3% 1,3-dioxane.
[0061] Example 10
[0062] The organic solvents are propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane (mass ratio of 50:50); the electrolyte lithium salt is 1.1 mol / L lithium difluorosulfonylimide; the additives are 1% lithium hexafluorophosphate, 1% lithium difluorophosphate, 2% PS, 1% tetraethylenesilane, 1% succinic anhydride and 0.5% 1,3-dioxane.
[0063] Experimental results
[0064] Discharge capacity after high temperature storage, battery thickness after high temperature storage, and low temperature discharge capacity: The discharge performance of the battery was tested using a Shenzhen Xinwei Battery Tester.
[0065] Four comparative examples and ten exemplary examples were mixed according to the formula to prepare electrolytes, which were then injected into pouch-type CP264260 lithium manganese primary batteries. The discharge capacity was tested after being stored at 60°C for 20 days followed by a 3A constant current discharge. The battery thickness was also tested after being stored at 60°C for 100 days. The -20°C low-temperature discharge capacity was tested by storing the batteries at -20°C for 16 hours, followed by a constant current discharge of 100mA to a cutoff voltage of 2.0V. The test results for all comparative examples and exemplary examples are shown in Table 1 below.
[0066] Table 1
[0067] Discharge capacity after high temperature storage Battery thickness after high temperature storage Low temperature discharge capacity Comparative Example 1 368.9mAh 3.25mm 436.9mAh Comparative Example 2 450.8mAh 4.62mm 563.4mAh Comparative Example 3 639.3mAh 3.02mm 565.7mAh Comparative Example 4 559.3mAh 2.61mm 165.7mAh Example 1 668.3mAh 2.94mm 743.1mAh Example 2 814.5mAh 2.95mm 780.2mAh Example 3 861.6mAh 2.63mm 773.7mAh Example 4 875.2mAh 2.61mm 763.2mAh Example 5 882.8mAh 2.60mm 779.4mAh Example 6 905.7mAh 2.60mm 786.9mAh Example 7 895.3mAh 2.61mm 882.2mAh Example 8 889.7mAh 2.60mm 839.7mAh Example 9 918.3mAh 2.60mm 826.5mAh Example 10 934.5mAh 2.60mm 979.5mAh
[0068] The data comparison of Comparative Examples 1 to 4 in Table 1 shows that the discharge tests after 20 days of high-temperature storage and at -20℃ show that with the optimized combination of electrolyte salts and the addition of lithium hexafluorophosphate to form a passivation film, the corrosion of aluminum foil by other corrosive substances is prevented. The discharge performance of each component after high-temperature storage is significantly different. However, in the DOL system, the addition of lithium hexafluorophosphate causes polymerization of the electrolyte after high-temperature storage. The main reason is that lithium hexafluorophosphate produces Lewis acid, which catalyzes the ring-opening polymerization of DOL, causing a sharp drop in the high and low temperature discharge performance of the battery.
[0069] The data comparison in Table 1 of the various examples and Comparative Example 3 shows that the high and low temperature performance of the battery was improved by optimizing the combination of organic solvents and electrolyte salts and adding the low-resistance additive lithium difluorophosphate. Specifically, the addition of 1-fluoro-2-(2-fluoroethoxy)ethane significantly improved the low-temperature performance of the battery, and as seen in Example 10, the addition of 1-fluoro-2-(2-fluoroethoxy)ethane stabilized lithium hexafluorophosphate. The added citrate anhydride, tetraethylenesilane, and 1,3-dioxane participated in the formation of the interface film on the positive electrode surface, and also had a positive impact on the battery discharge capacity.
[0070] The test results clearly show that the electrolyte formulation of this invention can significantly improve the discharge capacity of lithium manganese primary batteries after high-temperature storage, reduce thickness expansion after high-temperature storage, improve low-temperature discharge performance, and expand the application range of wide-temperature lithium primary batteries.
[0071] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be included within the scope of protection of the invention.
Claims
1. An electrolyte suitable for lithium primary batteries, comprising an electrolyte lithium salt, additives, and an organic solvent, characterized in that: The electrolyte lithium salt is any one or more of lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorosulfonylimide. The organic solvent includes propylene carbonate and 1-fluoro-2-(2-fluoroethoxy)ethane; The additive is one or more combinations of lithium difluorophosphate, 1,3-propanesulfonyl lactone, tetraethylenesilane, succinic anhydride, and citrate anhydride.
2. The electrolyte suitable for lithium primary batteries according to claim 1, characterized in that: The molar concentration of the electrolyte lithium salt is 0.01 mol / L to 2 mol / L.
3. The electrolyte for lithium primary batteries according to claim 2, characterized in that: The molar concentration of the electrolyte lithium salt is 0.8 mol / L to 1.5 mol / L.
4. The electrolyte for lithium primary batteries according to claim 1, characterized in that: The organic solvent accounts for 5% to 95% of the total mass of the electrolyte.
5. The electrolyte for lithium primary batteries according to claim 1, characterized in that: The mass ratio of propylene carbonate to 1-fluoro-2-(2-fluoroethoxy)ethane is 0.5 to 2:1; or, the organic solvent does not contain ethylene glycol dimethyl ether and 1,3-dioxolane.
6. The electrolyte for lithium primary batteries according to claim 1, characterized in that: The additives also include 1,3-dioxane and / or lithium hexafluorophosphate.
7. The electrolyte for lithium primary batteries according to claim 1, characterized in that: The total mass of the additives accounts for 0.05% to 15% of the total mass of the electrolyte.
8. The electrolyte for lithium primary batteries according to claim 1, characterized in that: The additive is one or more of 1,3-propanesulfonyl lactone, tetraethylenesilane, succinic anhydride, citrate anhydride, 1,3-dioxane, and lithium hexafluorophosphate, as well as lithium difluorophosphate, wherein the mass of the lithium difluorophosphate accounts for 0.1% to 5% of the total mass of the electrolyte.
9. A lithium primary battery, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that: The electrolyte is the electrolyte according to any one of claims 1 to 8.
10. The lithium primary battery according to claim 9, characterized in that: The active material of the positive electrode is manganese dioxide, and the active material of the negative electrode is lithium metal; and / or, the lithium primary battery is in the shape of a button cell, cylindrical cell, square cell, or pouch cell.