Thermal response solvated electrolyte, preparation method thereof and battery

Abstract

The invention relates to a thermal response solvated electrolyte, a preparation method thereof and a battery, the electrolyte is in a liquid state and is composed of a fluoride-free lithium salt and a fluoride-free organic solvent, and the fluoride-free organic solvent is propylene carbonate, ethylene carbonate, ethyl isopropyl sulfone, gamma-valerolactone, acetonitrile, dimethyl sulfoxide and N, N-dimethylformamide. The fluorine-free lithium salt is one of lithium bis (oxalato) borate, lithium iodide and lithium nitrate or a mixture of more of lithium bis (oxalato) borate, lithium iodide and lithium nitrate. Compared with the prior art, the electrolyte system provided by the invention is used for a lithium battery and meets the discharge requirements of wide temperature range and high rate, the thermal response solvated electrolyte is used for constructing a lithium metal battery, a lithium ion battery and a silicon negative electrode battery, the cycle performance of the battery can be effectively improved, the use temperature and rate capability of the battery are improved, and the service life of the battery is prolonged. Good application prospects are realized.

Description

Technical Field

[0001] This invention belongs to the field of electrolyte materials technology, and relates to a thermally responsive solvated electrolyte, its preparation method, and a battery. Background Technology

[0002] Lithium-ion batteries, with their superior energy density, have attracted significant attention and are increasingly widely used in energy storage fields such as electric vehicles, aerospace, and military. However, their electrochemical performance and thermal stability under extreme temperatures and high-rate conditions are often significantly limited. To address this challenge, developing electrolytes that can operate stably over a wide temperature range has become a highly promising strategy in this field, as the characteristics of the electrolyte are crucial to the battery's stable cycling and rapid charge-discharge performance.

[0003] Although ester-based (especially carbonate-based) electrolytes are widely used in lithium-ion batteries, they still face many challenges: poor compatibility with lithium metal, slow ion transport at room temperature, and susceptibility to short circuits due to lithium dendrite growth at high rates. Traditional carbonate electrolytes often struggle to simultaneously optimize interface stability, rapid lithium-ion dissociation, and ionic conductivity, directly limiting battery performance. Furthermore, their inherent flammability significantly increases battery safety risks. Therefore, developing electrolytes that combine high-rate performance, wide temperature tolerance, and non-flammability is particularly urgent for the development of high-performance batteries.

[0004] Therefore, researchers have proposed several strategies to address how to achieve electrolytes with wide temperature range and high rate capability, as well as their preparation methods and applications: For example, Chinese patent CN120127215A discloses a wide-temperature-range electrolyte for lithium-ion batteries. It uses one or more of the following lithium salts: lithium difluorobis(oxalato)phosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalatoborate, and lithium tetrafluoroborate; the organic solvent is a ternary mixed solvent; and the additives are a mixed solution of low-temperature performance additives, high-temperature stabilizing additives, and film-forming promoting additives. Wide-temperature operation of the lithium-ion battery is achieved by using fluorinated lithium salts and additives.

[0005] For example, literature ( Chem. Eng. J. 2023, (461, 141904) reports a locally high-concentration electrolyte based on 5 M bis(trifluoromethanesulfonyl)imide lithium salt and methylpropionic acid / fluoroethylene carbonate / 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether. The modified solvation structure and the introduction of lithium difluorooxalate borate additive enable rapid desolvation of lithium ions and the formation of a good electrode-electrolyte interface. This optimized electrolyte allows a 4.5 V Li||LCO battery to cycle 300 times at room temperature and 1 C (180 mA / g) with a capacity retention of 87.7%.

[0006] For example, literature ( ACS Energy Lett. (2025, 10, 1700-1711) A non-flammable electrolyte suitable for various climatic conditions is proposed, consisting of triethyl phosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium nitrate. The strong interaction between nitrate ions and triethyl phosphate broadens the electrolyte's melting point to −91.5°C. The ordered lithium-ion solvation structure with low desolvation energy contributes to the formation of a robust inorganic-organic hybrid solid electrolyte interface layer, significantly improving interfacial compatibility. Lithium metal batteries using the optimized triethyl phosphate-based electrolyte exhibit excellent electrochemical performance over a wide temperature range of −60–100°C.

[0007] For example, literature ( Angew. Chem. Int. Ed. 2025, (64, e202504116) designed a low-entropy and rapidly conducting lithium-ion electrolyte composed of lithium difluorooxalate borate and trans-difluoroethylene carbonate / methyl propionate, without the addition of any other components. The intermediate lithium salt of this electrolyte can further promote the rapid defluorination of fluorinated solvents, forming a lithium fluoride-rich interface. Li||LiNi 0.8 Co 0.1 Mn 0.1 O2 retains 90% of its capacity after 200 cycles at room temperature and a charge rate of 6 C. This electrolyte formulation provides excellent fast charge / discharge performance for lithium metal batteries.

[0008] For example, literature ( Energy Storage Mater. 2025, (75, 104105) reports a weak traction strategy that transforms the primary solvated sheath into a solvated structure dominated by lithium-ion-anion interactions by adding 2-fluorobenzyl alcohol as an additive. The optimized electrolyte promotes a greater anion-derived fluoride-rich lithium solid electrolyte interface layer, effectively suppressing lithium dendrite growth and lowering the deionization barrier. Li||LiNi using the improved electrolyte... 0.8 Co 0.1 Mn 0.1 O2 batteries retain 80% of their initial capacity after 720 cycles at 1 C, and even under harsh 5 C charge-discharge conditions, they retain 80% of their capacity after 250 cycles.

[0009] For example, literature ( Nat. Energy (2022, 7, 94-106) A series of fluorinated 1,2-diethoxyethanes were synthesized as electrolyte solvents. The optimal electrolyte, 1.2 M LiFSI, was dissolved in monofluorinated 1,2-diethoxyethane. Li||LiNi 0.8 Co 0.1 Mn0.1 O2 full cells retained over 80% capacity after 270 cycles at room temperature and 0.1 C rate. These fluorinated weakly solvated electrolytes exhibit a solvation structure and anion-derived interfacial chemistry similar to locally high-concentration electrolytes, showing great potential for achieving wide-temperature-range operation and high-rate performance in lithium metal batteries. It is noteworthy that both strategies inherently rely on fluorinated solvents: as diluents in locally high-concentration electrolytes and as the host solvent in weakly solvated electrolytes. While fluorinated compounds significantly improve battery performance, they are less environmentally friendly.

[0010] Traditional electrolyte systems inherently present performance trade-offs at different temperatures. Weakly solvated electrolytes exhibit low desolvation energy barriers at room temperature. f c < f e Organic solvents offer advantages such as good interfacial stability with solid electrolytes. However, at high temperatures, the lower flash point and higher volatility of organic solvents significantly increase the risk of vaporization and combustion. f c « f e Furthermore, the unstable interface leads to continuous electrolyte decomposition. Conversely, while traditional high-temperature electrolytes possess excellent ionic conductivity and high-temperature stability, their strong lithium-ion-solvent affinity results in slow desolvation kinetics at room temperature. f c > f e This restricts lithium-ion diffusion and charge transfer kinetics, leading to high overpotentials and promoting lithium dendrite growth. Therefore, neither of the two traditional strategies mentioned above can achieve a performance balance over a wide temperature range.

[0011] Electrolyte additives are crucial for modulating electrode interfaces, improving stability, and enhancing reaction rates, but their effectiveness is highly dependent on synergistic effects with solvents and salts. For batteries, simultaneously meeting the two key requirements of long cycle life and high-temperature performance is extremely challenging, especially under high-rate conditions. While fluorinated compounds can significantly improve performance, their environmental friendliness is poor. Currently, the development of fluorine-free electrolytes suitable for wide-temperature-range and high-rate batteries remains insufficient. Summary of the Invention

[0012] The purpose of this invention is to provide a thermally responsive solvated electrolyte, its preparation method, and a battery. By regulating the electrostatic interactions in the solvated structure, the electrolyte can dynamically respond to temperature changes, thereby achieving stable operation of the battery over a wide temperature range and at high rates.

[0013] The objective of this invention can be achieved through the following technical solutions: In one aspect, the present invention provides a thermally responsive solvated electrolyte, which is in a liquid state and is composed of a fluorine-free lithium salt and a fluorine-free organic solvent, wherein the fluorine-free organic solvent is one of propylene carbonate, ethylene carbonate, ethyl isopropyl sulfone, γ-valerolactone, acetonitrile, dimethyl sulfoxide, 4-ethyl-1,3-dioxane-2-one and N,N'-dimethylformamide, and the fluorine-free lithium salt is one or a mixture of several of lithium dioxolane-borate, lithium iodide and lithium nitrate.

[0014] Furthermore, the concentration of the fluorine-free lithium salt is 1.0 ~ 3.0 mol / L.

[0015] Furthermore, the electrolyte water content is less than 20 ppm.

[0016] Furthermore, the electrolyte operates at a temperature of 25~120℃.

[0017] In another aspect, the present invention also provides a method for preparing a thermally responsive solvated electrolyte, wherein a fluorine-free lithium salt and a fluorine-free organic solvent are mixed uniformly in an inert atmosphere to obtain the thermally responsive solvated electrolyte.

[0018] Furthermore, the inert atmosphere is provided by nitrogen or argon.

[0019] In a third aspect, the present invention provides a battery that uses a thermally responsive solvated electrolyte as described in the first aspect above as the electrolyte.

[0020] Furthermore, the battery is a silicon anode battery, a lithium-ion battery, or a lithium metal battery.

[0021] Furthermore, the battery cell is any one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based, and sulfur-based systems.

[0022] In electrolyte solutions, the interaction between lithium ions and anions is mainly through electrostatic forces ( f e This is achieved through coordination forces, while the interaction between lithium ions and the solvent mainly involves coordination forces. f c The electrostatic interactions between cations and anions in the thermally responsive solvated electrolyte provided by this invention cancel each other out with the solvent coordination strength, resulting in a suitable solvation structure at room temperature. f c ≈ f e As temperature increases, molecular thermal motion intensifies, prompting dynamic recombination of the lithium salt in the electrolyte. Through strong electrostatic interactions, the participation of the solvent in the first solvation sheath gradually decreases, and this recombination constructs a solvation structure dominated by anions. f c <f e ).

[0023] Therefore, as the temperature increases, the participation of the solvent in the main solvation shell gradually decreases, thereby promoting the formation of an interface layer derived from inorganic materials. The battery exhibits long cycle life and high capacity retention at room temperature. Furthermore, the battery maintains a long cycle life even under high temperature and high rate conditions.

[0024] Compared with the prior art, the present invention has the following advantages: (1) The designed electrolyte is modulated by electrostatic interaction to construct a dynamic solvation structure with thermal response characteristics: it exhibits a moderate solvation structure at room temperature, while transforming into a weak solvation structure at high temperature. This structural characteristic easily induces the formation of anion-derived stable interfaces.

[0025] (2) Batteries using the electrolyte system in this application have excellent wide temperature adaptability, high rate performance and reliable safety performance.

[0026] (3) Compared with existing electrolyte systems, the electrolyte in this invention is inexpensive, does not require the introduction of additional fluorine-containing additives, is environmentally friendly, and has no special requirements for the use environment.

[0027] (4) The raw materials used in the electrolyte system in this application are mostly common lithium salts and solvents, which are widely available and have simple preparation processes. They do not require special expensive equipment and complex processes, and are easy to achieve large-scale industrial production. They have good economic benefits and market application prospects. Attached Figure Description

[0028] Figure 1 The electrochemical cycling curves of the lithium metal battery using the thermally responsive solvated electrolyte of Example 1 at room temperature are shown. Figure 2 The electrochemical cycling curves of the thermally responsive solvated electrolyte used in Example 1 at 80°C and different rate ratios are shown. Figure 3 Flame retardant performance diagrams of the thermally responsive solvated electrolyte of Example 1 and its comparative examples; Figure 4 The electrochemical cycling curves of the thermally responsive solvated electrolyte of Example 1 and its comparative example at different temperatures are shown. Figure 5 The electrochemical cycling curve of the thermally responsive solvated electrolyte used in Example 2 at 80°C is shown. Figure 6 The electrochemical cycling curves of Example 3 at room temperature are shown. Figure 7 The electrochemical cycling curves of Example 4 at room temperature and high temperature are used; Figure 8 The electrochemical cycling curve of Example 5 at 60°C was plotted. Figure 9 The electrochemical cycling curve of Example 5 at 80°C was plotted. Figure 10 The electrochemical cycling curves from Example 6 at room temperature are used; Figure 11 The electrochemical cycling curve at 80°C was obtained using Example 6; Figure 12 The electrochemical cycling curve of Comparative Example 3 at room temperature was used; Figure 13 To obtain the electrochemical cycling curve of Comparative Example 3 at 80 °C; Figure 14 The electrochemical cycling curve of Comparative Example 5 at room temperature was used; Figure 15 To obtain the electrochemical cycling curve of Comparative Example 5 at 60 °C; Figure 16 The electrochemical cycling curve of Comparative Example 6 at room temperature was used; Figure 17 The electrochemical cycling curve of Comparative Example 6 at 80 °C was used. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0031] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0034] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0035] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0036] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0037] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0038] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0039] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0041] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0042] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0043] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0044] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0045] Example 1: Prepare a propylene carbonate solution with a lithium salt concentration of 1.0 mol / L. The lithium salt is lithium dioxalate borate with a concentration of 1.0 mol / L.

[0046] Room temperature performance testing: This electrolyte system was used with lithium metal as the negative electrode in LiNi 0.5 C 0.2 M 0.3 Full-cell testing with O2 as the positive electrode revealed that the average coulombic efficiency at room temperature reached 99.7%, the cycle life reached 180 cycles, and the capacity retention was >80%. Its room-temperature cycling performance was as follows: Figure 1 As shown, battery-1 and battery-2 are parallel samples.

[0047] High-Temperature, High-Rate Performance Testing: This thermally responsive solvated electrolyte exhibits excellent thermal stability at high temperatures. The same electrolyte system was used to assemble a full cell with the above structure, and tests were conducted at 80°C and a 2C rate. The results showed that the average coulombic efficiency of the battery was 99%, and the capacity retention after 173 cycles was >80%. Its high-temperature, high-rate cycling performance is as follows: Figure 2 As shown.

[0048] This thermally responsive solvated electrolyte exhibits excellent safety and significant flame-retardant properties; it does not ignite or explode. Its flame-retardant performance test results are as follows: Figure 3 As shown in (a), the thermally responsive solvated electrolyte exhibited flame-retardant properties after being heated by an external ignition source for 20 s. Over a wide temperature range (30–120°C), this electrolyte system demonstrated excellent thermal and cycling stability, exhibiting superior thermal response characteristics, such as… Figure 4 As shown, it supports the battery to achieve safe and long-term operation.

[0049] Example 2: Prepare a 1.0 mol / L ethyl isopropyl sulfone solution with lithium dioxaborate as the lithium salt and a concentration of 1.0 mol / L.

[0050] This electrolyte system is used with lithium metal as the negative electrode, LiNi 0.5 C 0.2 M 0.3 Full cell testing using O2 as the positive electrode. When the temperature rises to 80℃, the battery's average coulombic efficiency reaches 98.9%, cycle life reaches 30 cycles, and capacity retention is ~100%. Its cycle performance is as follows: Figure 5 As shown.

[0051] Example 3: Prepare a γ-valerol solution with a concentration of 2.6 mol / L, using lithium dioxalatoborate as the lithium salt with a concentration of 2.6 mol / L.

[0052] This electrolyte system is used with lithium metal as the negative electrode, LiNi 0.5 C 0.2 M 0.3 Full-cell testing using O2 as the positive electrode. Tests were conducted over a wide temperature range (30–80°C), and the electrolyte system exhibited excellent thermal and cycle stability, supporting safe and long-term battery operation across a wide temperature range. Its cycle performance at 30°C is as follows: Figure 6 As shown in the figure. Test results show that the battery has an average coulombic efficiency of 98.7% and a capacity retention of 98% after 17 cycles at room temperature.

[0053] Example 4: A propylene carbonate solution with a lithium salt concentration of 2.6 mol / L was prepared. The lithium salt was lithium dioxalate borate with a concentration of 2.6 mol / L. This electrolyte system was used with lithium metal as the negative electrode, LiNi... 0.5 C 0.2 M 0.3 Full cell test with O2 as the positive electrode.

[0054] Tested over a wide temperature range (30~120°C), this electrolyte system exhibited excellent thermal and cycle stability, supporting safe and long-term battery operation across a wide temperature range. Its cycle performance at 30°C and 80°C is as follows: Figure 7 As shown in the figure. Test results indicate that the lithium metal battery retains 97.6% of its capacity after 17 cycles at 30°C. The average coulombic efficiency is 97.6% after 44 cycles at 80°C.

[0055] Example 5: An ethyl isopropyl sulfone solution with a lithium salt concentration of 2.6 mol / L was prepared. The lithium salt was lithium difluorooxalate borate with a concentration of 2.6 mol / L. This electrolyte system was used with lithium metal as the negative electrode in a LiNi... 0.5 C 0.2 M 0.3 Full cell test with O2 as the positive electrode.

[0056] Tested at high temperatures of 60°C and 80°C, this electrolyte system exhibited excellent thermal and cycle stability, supporting safe and long-term battery operation over a wide temperature range. Its cycle performance at 60°C is as follows: Figure 8 As shown in the figure. Test results show that the battery has an average coulombic efficiency of 98.2% and a capacity retention of 100% after 17 cycles at 60°C. Its cycling performance at 80°C is as follows. Figure 9 As shown in the figure. Test results show that the battery has an average coulombic efficiency of 97.7% and a capacity retention of 100% after 13 cycles at 80°C.

[0057] Example 6: A 1 mol / L solution of 4-ethyl-1,3-dioxane-2-one was prepared, with lithium dioxaborate as the lithium salt at a concentration of 1 mol / L. This electrolyte system was then used with lithium metal as the negative electrode in a LiNi... 0.5 C 0.2 M 0.3 Full cell test with O2 as the positive electrode.

[0058] At room temperature and 80 o Tested under C environment, this electrolyte system exhibited excellent thermal and cycle stability, supporting safe and long-term battery operation over a wide temperature range. Its cycle performance at room temperature is as follows: Figure 10 As shown, the test results indicate that the battery has an average coulombic efficiency of 98.4% and a capacity retention of 78% after 29 cycles at 30°C. Its cycling performance at 80°C is as follows... Figure 11 As shown in the figure. Test results show that the battery has an average coulombic efficiency of 99.4% and a capacity retention of 100% after 82 cycles at 80°C.

[0059] Example 7: A propylene carbonate solution with a lithium salt concentration of 1.0 mol / L was prepared, consisting of lithium dioxaborate and lithium iodide (volume ratio 9:1), with a total concentration of 1.0 mol / L. This electrolyte system was then used to test a full cell with lithium metal as the negative electrode and lithium-rich manganese as the positive electrode.

[0060] Examples 1-7 show that when the temperature rises to 25~120°C... o At C, the electrolyte system exhibits excellent thermal and cycle stability, supporting safe and long-term operation of the battery over a wide temperature range and at high rates.

[0061] Comparative Example 1 The comparison with Example 1 was largely the same, except that the organic solvent propylene carbonate was replaced with ethylene carbonate and diethyl carbonate (volume ratio 1:1). When heated by an external ignition source for 20 seconds, the electrolyte in Comparative Example 1 burned rapidly, and the test results were as follows. Figure 3 As shown in (b), this electrolyte system was used with lithium metal as the negative electrode in LiNi... 0.5 C 0.2 M 0.3 Full-cell testing with O2 as the positive electrode. When the temperature rises to 120°C, the battery capacity rapidly decreases, and its temperature cycling performance is as follows: Figure 4 As shown.

[0062] Comparative Example 2 Compared to Example 1, the electrolyte was largely the same, except that lithium dioxalatoborate was replaced with lithium hexafluorophosphate, and 5 wt% vinylene carbonate was added. When an ignition source was brought close for 20 seconds, the electrolyte of Comparative Example 2 exhibited significant flame-retardant properties, neither igniting nor exploding. Its flame-retardant performance test results are as follows: Figure 3 As shown in (c), this electrolyte system is used with lithium metal as the negative electrode, LiNi 0.5 C 0.2 M 0.3 Full-cell testing with O2 as the positive electrode. When the temperature rises to 80℃, the battery capacity rapidly decreases, and its temperature cycling performance is as follows: Figure 4 As shown.

[0063] Comparative Example 3 Compared to Example 1, all other conditions remained unchanged, except that the solvent propylene carbonate was replaced with γ-valerol, and the electrolyte system of Comparative Example 3 was used with lithium metal as the negative electrode, LiNi 0.5 C 0.2 M 0.3 Full cell testing with O2 as the positive electrode. Its room temperature cycling performance curve is shown below. Figure 12As shown, the test results indicate that the battery has an average coulombic efficiency of 93.8% at room temperature, and its capacity retention is only >73% after 33 cycles. Its high-temperature cycling performance is as follows... Figure 13 As shown, the test results indicate that the battery's capacity significantly decreases after 80 cycles at 80°C, and drops to 0 mAh / cm³ after 100 cycles. 2 Therefore, in high-temperature environments, the low flash point and high volatility of organic solvents significantly increase the risk of vaporization and combustion. f c « f e Furthermore, an unstable interface can lead to the continuous decomposition of the electrolyte, which in turn affects the electrochemical performance of the battery.

[0064] Comparative Example 4 Compared to Example 1, with all other conditions unchanged, lithium dioxalate borate was replaced with lithium nitrate. After testing, it was found that 1 mol / L lithium nitrate could not be completely dissolved in propylene carbonate.

[0065] Comparative Example 5 differed from Example 1 in that all other conditions remained unchanged, except that the lithium salt lithium dioxalatoborate was replaced with the fluorinated lithium salt lithium bis(trifluoromethanesulfonyl)imide. The electrolyte system of Comparative Example 5 was used with lithium metal as the negative electrode, LiNi... 0.5 C 0.2 M 0.3 Full cell testing with O2 as the positive electrode. Its room temperature cycling performance curve is shown below. Figure 14 As shown, the test results indicate that the battery has an average coulombic efficiency of 83.6% at room temperature, and its capacity rapidly decays to 0 mAh / cm³ after 27 cycles. 2 Its high-temperature cycling performance is as follows: Figure 15 As shown, the test results indicate that during the first charge cycle at 60°C, the electrolyte continues to decompose, and the voltage drops.

[0066] Comparative Example 6 Compared to Example 1, all other conditions remained unchanged, except that 5 vt.% of fluoroethylene carbonate was added. The electrolyte system of Comparative Example 6 was used with lithium metal as the negative electrode, LiNi 0.5 C 0.2 M 0.3 Full cell testing with O2 as the positive electrode. Its room temperature cycling performance curve is shown below. Figure 16 As shown, the test results indicate that the battery has an average coulombic efficiency of 99.4% at room temperature and a capacity retention of 93.7% after 38 cycles. Its high-temperature cycling performance is as follows... Figure 17 As shown, the test results indicate that during the first charge cycle at 80°C, the electrolyte continues to decompose, and the voltage drops.

[0067] Comparative Examples 1-6 show that within a temperature range of 25~120°C, these electrolyte systems failed to maintain the excellent thermal and cycle stability demonstrated in the examples, and could not support the safe and long-term operation of the battery under wide temperature range and high rate conditions.

[0068] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A thermally responsive solvated electrolyte, characterized in that, It is in liquid state and is composed of a fluorine-free lithium salt and a fluorine-free organic solvent. The fluorine-free organic solvent is one of propylene carbonate, ethylene carbonate, ethyl isopropyl sulfone, γ-valerol, acetonitrile, dimethyl sulfoxide, 4-ethyl-1,3-dioxane-2-one, and N,N'-dimethylformamide. The fluorine-free lithium salt is one or a mixture of several of lithium dioxaborate, lithium iodide, and lithium nitrate.

2. The thermally responsive solvated electrolyte according to claim 1, characterized in that, The concentration of the fluorine-free lithium salt is 1.0 ~ 3.0 mol / L.

3. The thermally responsive solvated electrolyte according to claim 1, characterized in that, Its water content is less than 20 ppm.

4. The thermally responsive solvated electrolyte according to claim 1, characterized in that, Its operating temperature is 25~120℃.

5. A method for preparing a thermally responsive solvated electrolyte as described in any one of claims 1-4, characterized in that, In an inert atmosphere, a fluorine-free lithium salt and a fluorine-free organic solvent are mixed evenly to obtain the thermally responsive solvated electrolyte.

6. The method for preparing a thermally responsive solvated electrolyte according to claim 5, characterized in that, The inert atmosphere is provided by nitrogen or argon.

7. A battery, characterized in that, A thermally responsive solvated electrolyte as described in any one of claims 1-4 is used as the electrolyte.

8. A battery according to claim 7, characterized in that, It is a silicon anode battery, lithium-ion battery, or lithium metal battery.

9. A battery according to claim 7, characterized in that, Its battery cells are any of the following systems: lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based, and sulfur.

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