Chlorinated electrolyte for high voltage lithium metal battery and electrochemical device

Abstract

The application provides a chlorinated electrolyte for high-voltage lithium metal batteries and an electrochemical device. The chlorinated electrolyte for high-voltage lithium metal batteries comprises a lithium salt, a solvent and an additive; the solvent is composed of a chlorinated linear carbonate and a dichloroalkane; the chlorinated linear carbonate has a general structural formula as shown in formula (1); R is an alkyl group with 1-4 carbon atoms; the dichloroalkane has a general structural formula as shown in formula (2); and n is an integer of 1-7. The chlorinated electrolyte for high-voltage lithium metal batteries has good compatibility with a lithium metal negative electrode and a high-voltage positive electrode, and the safety of the prepared lithium metal battery is also significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, and particularly relates to a chloride electrolyte and electrochemical device for high-voltage lithium metal batteries. Background Technology

[0002] Lithium metal batteries with high-nickel or lithium cobalt oxide cathodes have attracted widespread attention and research due to their ultra-high energy density (up to 500 Wh / kg), making them a promising next-generation electrochemical energy storage device. However, the energy storage mechanism of lithium metal anode deposition / stripping easily leads to the growth of dendritic lithium dendrites, causing a series of safety issues. Furthermore, its low redox potential results in severe spontaneous side reactions between the anode and the electrolyte. Compared to traditional graphite anodes, lithium metal anodes exhibit greater volume changes during charge and discharge, causing electrode pulverization and further exacerbating side reactions between the lithium metal anode and the electrolyte, ultimately leading to rapid capacity decay in lithium metal batteries. In addition, for high-nickel and lithium cobalt oxide cathodes, especially at high charging cutoff voltages, irreversible phase transitions and the dissolution of transition metal ions cause cathode structural collapse. High-valence transition metal ions catalyze electrolyte decomposition, further shortening the cycle life of lithium metal batteries, and the gas generation caused by electrolyte decomposition within the battery is severe. The aforementioned performance and safety issues greatly limit the practical application of lithium metal batteries. Therefore, it is urgent to develop new technologies to solve the problems faced by the positive and negative electrodes and promote the industrialization of lithium metal batteries.

[0003] Electrolytes, as a crucial component of batteries, not only influence lithium-ion transport performance but also, through their own decomposition, construct electrode / electrolyte interfaces on the positive and negative electrode surfaces, regulating electrode structural stability and thus affecting battery performance. Therefore, high-performance electrolyte design is paramount for lithium metal batteries. Currently, to improve the lifespan and safety of lithium metal batteries, the development of fluorinated electrolytes, high-concentration electrolytes, and locally high-concentration electrolytes has significantly enhanced their performance. However, the extensive use of fluorinated solvents or lithium salts means these electrolyte technologies still face challenges such as high cost and poor environmental friendliness, and their safety performance requires further optimization.

[0004] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a chloride electrolyte and electrochemical device for high-voltage lithium metal batteries, which is compatible with both high-voltage positive electrode and lithium metal negative electrode, has high safety and long cycle life, and is environmentally friendly and low-cost.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, a chloride electrolyte for high-voltage lithium metal batteries is provided, comprising a lithium salt, a solvent, and an additive; said solvent is composed of a chlorinated linear carbonate and a dichloroalkane, said chlorinated linear carbonate having a general structural formula as shown in formula (1):

[0008] (1);

[0009] Wherein, R is an alkyl group having 1 to 4 carbon atoms;

[0010] The dichloroalkane has a general structural formula as shown in formula (2):

[0011] (2);

[0012] Where n is an integer from 1 to 7.

[0013] Preferably, the chlorolinear carbonate is at least one of chloromethyl carbonate, chloromethyl carbonate, chloromethyl carbonate isopropyl carbonate, chloromethyl carbonate sec-butyl carbonate, and chloromethyl carbonate tert-butyl carbonate.

[0014] Preferably, the dichloroalkane is at least one selected from 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,7-dichloroheptane, and 1,8-dichlorooctane.

[0015] Preferably, in the solvent, the volume ratio of the chlorolinear carbonate to the dichloroalkane is 1:(0.5~3).

[0016] Preferably, the additive is a fluorocyclic carbonate.

[0017] Preferably, the fluorocyclic carbonate is at least one of fluoroethylene carbonate and difluoroethylene carbonate.

[0018] Preferably, in the chlorinated electrolyte, the volume ratio of the additive to the solvent is (0.01~0.1):1.

[0019] Preferably, the lithium salt is at least one of lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(pentafluoroethanesulfonyl)imide.

[0020] Preferably, the concentration of the lithium salt in the chlorination electrolyte is 0.5~2 mol / L.

[0021] In a second aspect, an electrochemical device is provided, comprising: a positive electrode, a diaphragm, a negative electrode, and the chloride electrolyte described in the first aspect.

[0022] Compared to existing electrolyte technologies, the chloride electrolyte for high-voltage lithium metal batteries provided in this invention has the following advantages:

[0023] On the one hand, the chlorine atoms in the chlorinated linear carbonate molecules in the solvent, which have a strong electron-withdrawing effect, can weaken the electron cloud density of oxygen atoms in the carbonate solvent molecule structure, thereby reducing its affinity for Li. + The coordination ability of chlorine atoms enables anions to enter the internal solvation structure at lower lithium salt concentrations, ultimately constructing an inorganic-rich interface formed by anion decomposition and regulating the structural stability of the positive and negative electrodes. On the other hand, the introduction of chlorine atoms lowers the molecular orbital energy levels of the carbonate solvent, enhancing the electrolyte's antioxidant capacity and helping to ensure stable operation of the lithium metal battery at high voltages (in this invention, "high voltage" refers to a working voltage higher than 4.4 V, preferably 4.4 to 4.7 V). Furthermore, the solvent containing chlorine atoms decomposes to form a low-Li... + The LiCl interface composition, characterized by a diffusion barrier, wide bandgap, and high surface energy, can further suppress lithium dendrite formation, promote dense lithium metal deposition, and significantly improve the cycle stability of the lithium metal anode. Furthermore, adjusting the chain length and configuration of the alkyl groups in the chlorolinear carbonate molecule, utilizing steric hindrance, can further hinder the reaction between oxygen atoms in the carbonate molecule and Li. + By bringing them closer together, the ion-dipole interaction between them is weakened. In other words, by modulating the alkyl chain of chlorolinear carbonates, the steric hindrance of the solvent molecules can be increased, further weakening the interaction between the carbonate solvent and Li. + The coordination ability of the lithium salt is beneficial for achieving a wider electrochemical stability window at lower lithium salt concentrations. Furthermore, by controlling the alkyl chain of the dichloroalkanes in the solvent, the liquid phase temperature range and maximum lithium salt dissolution concentration of the chlorinated electrolyte can be optimized, reducing the risk of thermal runaway in lithium metal batteries.

[0024] Furthermore, the additives utilize fluorinated cyclic carbonates, which, through decomposition, form LiF and highly elastic polymers, thus contributing to enhanced Li interfacial bonding. + Its transport and deformation resistance, combined with chlorinated solvents, form a bilayer interface between the inorganic inner layer and the polymer outer layer, further improving the stability of the interface.

[0025] The chloride electrolyte of this invention has good compatibility with both lithium metal anode and high-voltage cathode, providing a new technical solution for simultaneously achieving high performance and high safety of high-voltage lithium metal batteries, and playing a significant positive role in promoting the large-scale application of lithium metal batteries. Attached Figure Description

[0026] Figure 1The deposition morphology of lithium metal on a Cu electrode is shown when using the chlorination electrolyte of Example 1 of the present invention.

[0027] Figure 2 The deposition morphology of lithium metal on a Cu electrode is shown when using the electrolyte of Comparative Example 1.

[0028] Figure 3 The deposition morphology of lithium metal on a Cu electrode is shown when using the electrolyte of Comparative Example 2.

[0029] Figure 4 The lithium deposition / stripping coulombic efficiency test results of batteries using the electrolytes of Example 1 and Comparative Examples 1-2 of the present invention are shown.

[0030] Figure 5 The oxidation voltage test results of batteries using the electrolytes of Example 1 and Comparative Example 1 of the present invention are shown in the open-circuit voltage range of ~6.0 V. Detailed Implementation

[0031] To make the objectives, technical solutions, and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. The embodiments described below are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art in conjunction with the embodiments of the present invention without creative effort are within the scope of protection of the present invention. It should be emphasized that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0032] This invention provides a chloride electrolyte for high-voltage lithium metal batteries, comprising a lithium salt, a solvent, and additives; the solvent is composed of a chlorinated linear carbonate and a dichloroalkane, wherein the chlorinated linear carbonate has a general structural formula as shown in formula (1):

[0033] (1);

[0034] Wherein, R is an alkyl group having 1 to 4 carbon atoms;

[0035] The dichloroalkane has a general structural formula as shown in formula (2):

[0036] (2);

[0037] Where n is an integer from 1 to 7.

[0038] In some embodiments, the chlorolinear carbonate is at least one of chloromethyl carbonate (where R is methyl in formula (1)), chloromethyl carbonate (where R is ethyl in formula (1)), chloromethyl carbonate isopropyl (where R is isopropyl in formula (1)), chloromethyl carbonate sec-butyl (where R is sec-butyl in formula (1)), and chloromethyl carbonate tert-butyl (where R is tert-butyl in formula (1)).

[0039] In some embodiments, the dichloroalkane is at least one selected from 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,7-dichloroheptane, and 1,8-dichlorooctane.

[0040] In some embodiments, the volume ratio of the chlorolinear carbonate to the dichloroalkane in the solvent is 1:(0.5~3). The volume ratio of chlorolinear carbonate to dichloroalkane in the solvent affects the solubility of lithium salt and the performance of the electrolyte. When the volume ratio is less than 1:0.5, the electrochemical performance is poor, while when it is greater than 1:3, the lithium salt cannot be completely dissolved. More preferably, the volume ratio of the chlorolinear carbonate to the dichloroalkane is 1:(0.5~1.5).

[0041] In some embodiments, the additive is a fluorocyclic carbonate; further, the fluorocyclic carbonate is at least one of fluoroethylene carbonate and difluoroethylene carbonate.

[0042] In some embodiments, the volume ratio of the additive to the solvent in the chlorinated electrolyte is (0.01~0.1):1.

[0043] In some embodiments, the lithium salt is at least one of lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(pentafluoroethanesulfonyl)imide.

[0044] In some embodiments, the concentration of the lithium salt in the chlorinated electrolyte is 0.5~2 mol / L.

[0045] The present invention also provides an electrochemical device comprising: a positive electrode, a diaphragm, a negative electrode, and the aforementioned chloride electrolyte.

[0046] In some embodiments, the positive electrode is high in nickel (such as LiNi). 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811) or lithium cobalt oxide positive electrode; the separator is a polyolefin separator; the negative electrode is a lithium metal or lithium alloy negative electrode.

[0047] The following describes specific embodiments of the present invention.

[0048] Example 1

[0049] This embodiment provides a chloride electrolyte for high-voltage lithium metal batteries, comprising a lithium salt, a solvent, and a fluorinated cyclic carbonate additive. The lithium salt is lithium bis(fluorosulfonyl)imide (LiFSI) at a concentration of 1.5 mol / L. The solvent consists of isopropyl chloromethyl carbonate (CMiPC) and 1,3-dichloropropane (DCP) in a volume ratio of 1:1. The fluorinated cyclic carbonate additive is fluoroethylene carbonate (FEC) in a volume ratio of 0.05:1 to the solvent.

[0050] The specific preparation steps of the chloride electrolyte in Example 1 were all completed in an argon-filled glove box, and included the following steps:

[0051] 1. Measure 0.5 mL of CMiPC and 0.5 mL of DCP into glass bottles and mix them thoroughly by magnetic stirring.

[0052] 2. Weigh 1.575 mmol LiFSI and add it to the mixed solution from step 1. Stir magnetically to dissolve it completely.

[0053] 3. Measure 0.05 mL of FEC and add it to the mixed solution in step 2. Stir magnetically to obtain the final chloride electrolyte.

[0054] Example 2

[0055] The difference between the chlorination electrolyte in this embodiment and that in Example 1 is that the concentration of lithium salt LiFSI is 2.0 mol / L. The solvent consists of chloromethyl ethyl carbonate (CMEC) and 1,2-dichloroethane (DCE), with a volume ratio of CMEC to DCE of 1:1.5. The volume ratio of fluoroethylene carbonate (FEC) to the solvent is 0.05:1. Everything else is the same as in Example 1.

[0056] The specific preparation steps of the chloride electrolyte in Example 2 were all completed in an argon-filled glove box, and included the following steps:

[0057] 1. Measure 0.5 mL of CMEC and 0.75 mL of DCE into glass bottles and mix them thoroughly by magnetic stirring.

[0058] 2. Weigh 2.625 mmol LiFSI and add it to the mixed solution from step 1. Stir the solution magnetically until it is completely dissolved.

[0059] 3. Measure 0.0625 mL of FEC and add it to the mixed solution in step 2. Stir magnetically to obtain the final chloride electrolyte.

[0060] Example 3

[0061] The difference between the chlorination electrolyte in this embodiment and that in Example 1 is that the concentration of lithium salt LiFSI is 1.0 mol / L. The solvent consists of tert-butyl chloromethyl carbonate (CMtBC) and 1,2-dichloroethane (DCE), with a volume ratio of CMtBC to DCE of 1:1. The volume ratio of fluoroethylene carbonate (FEC) to the solvent is 0.05:1. Everything else is the same as in Example 1.

[0062] The specific preparation steps of the chloride electrolyte in Example 3 were all completed in an argon-filled glove box, and included the following steps:

[0063] 1. Measure 0.5 mL of CMtBC and 0.5 mL of DCE into glass bottles and mix them thoroughly by magnetic stirring.

[0064] 2. Weigh 1.05 mmol LiFSI and add it to the mixed solution from step 1. Stir magnetically to dissolve it completely.

[0065] 3. Measure 0.05 mL of FEC and add it to the mixed solution in step 2. Stir magnetically to obtain the final chloride electrolyte.

[0066] Example 4

[0067] The difference between the chlorination electrolyte in this embodiment and that in Example 1 is that the lithium salt LiFSI concentration is 1.5 mol / L. The solvent consists of isopropyl chloromethyl carbonate (CMiPC) and 1,4-dichlorobutane (DCB), with a volume ratio of CMiPC to DCB of 1:0.5. The fluorocyclic carbonate additive is difluoroethylene carbonate (DFEC), with a volume ratio of 0.02:1 to the solvent. Everything else is the same as in Example 1.

[0068] The specific preparation steps of the chloride electrolyte in Example 4 were all completed in an argon-filled glove box, and included the following steps:

[0069] 1. Measure 1 mL of CMiPC and 0.5 mL of DCB into glass bottles and mix them thoroughly by magnetic stirring.

[0070] 2. Weigh 2.295 mmol LiFSI and add it to the mixed solution from step 1. Stir the solution magnetically until it is completely dissolved.

[0071] 3. Measure 0.03 mL of DFEC and add it to the mixed solution in step 2. Stir magnetically to obtain the final chloride electrolyte.

[0072] Comparative Example 1

[0073] Comparative Example 1 provides an electrolyte comprising a lithium salt, a cyclic carbonate solvent, and a linear carbonate solvent. The lithium salt is lithium hexafluorophosphate (LiPF6) with a concentration of 1.0 mol / L. The cyclic carbonate solvent is ethylene carbonate (EC), and the linear carbonate solvent is ethyl methyl carbonate (EMC), with a volume ratio of EC to EMC of 3:7.

[0074] The specific preparation steps of the electrolyte in Comparative Example 1 were all completed in an argon-filled glove box, and included the following steps:

[0075] 1. Measure 0.3 mL of EC and 0.7 mL of EMC into glass bottles and mix them thoroughly by magnetic stirring.

[0076] 2. Weigh 1.0 mmol of LiPF6 and add it to the mixed solution in step 1. Stir it magnetically to dissolve it completely to obtain the final electrolyte.

[0077] Comparative Example 2

[0078] Comparative Example 2 provides an electrolyte comprising a lithium salt, a linear carbonate solvent, a chloroalkane solvent, and a fluorocyclic carbonate additive. The lithium salt is lithium bis(fluorosulfonyl)imide (LiFSI) at a concentration of 1.5 mol / L. The linear carbonate solvent is ethyl methyl carbonate (EMC), and the chloroalkane solvent is 1,3-dichloropropane (DCP), with a volume ratio of EMC to DCP of 1:1. The fluorocyclic carbonate additive is fluoroethylene carbonate (FEC), with a volume ratio of FEC to the solvent of 0.05:1.

[0079] The specific preparation steps of the electrolyte in Comparative Example 2 were all completed in an argon-filled glove box, and included the following steps:

[0080] 1. Measure 0.5 mL of EMC and 0.5 mL of DCP into glass bottles and mix them thoroughly by magnetic stirring.

[0081] 2. Weigh 1.575 mmol LiFSI and add it to the mixed solution from step 1. Stir magnetically to dissolve it completely.

[0082] 3. Measure 0.05 mL of FEC and add it to the mixed solution in step 2. Stir magnetically to obtain the final electrolyte.

[0083] Performance testing: Li||Cu batteries, Li||Al batteries, and Li||NCM811 batteries assembled using the electrolytes of Examples 1-4 and Comparative Examples 1-2 were tested for lithium deposition / stripping morphology and coulombic efficiency, electrolyte oxidation voltage, and charge-discharge cycle performance.

[0084] 1. Lithium deposition / stripping test method

[0085] Battery assembly: In a glove box, Li||Cu coin cells were assembled using lithium metal as the negative electrode, Celgard 2500 porous polymer membrane as the separator, and Cu as the positive electrode. The cells were left to stand for 6 hours to allow the electrodes to be fully wetted.

[0086] Lithium deposition morphology testing: Constant current charge-discharge tests were conducted using a charge-discharge testing device in a constant temperature chamber at 25 °C. First, a stable solid-state electrolyte interface film was pre-constructed within a voltage range of 0.01–1.0 V, with a current density set to 0.05 mA / cm². 2 The cycle was repeated for 5 rounds. Then, lithium metal for morphology observation was deposited on the Cu electrode at a current density of 0.5 mA / cm². 2 The discharge time was set to 4 h, corresponding to a lithium deposition capacity of 2 mAh / cm³. 2 .

[0087] Lithium deposition / stripping coulombic efficiency testing: Constant current charge-discharge tests were conducted using a charge-discharge testing apparatus in a 25 °C constant-temperature chamber. First, a stable solid-state electrolyte interface film was pre-constructed within a voltage range of 0.01–1.0 V, with a current density set to 0.05 mA / cm². 2 The cycle was repeated for 5 cycles. Then, a lithium deposition / stripping coulombic efficiency cycle test was performed, with the charge / discharge current density set to 0.5 mA / cm². 2 The discharge time was set to 2 h, the charging voltage was set to 1.0 V, the charging capacity and the discharge capacity were recorded, and the lithium deposition / stripping coulombic efficiency was calculated according to the following formula.

[0088] Formula for calculating coulombic efficiency per charge-discharge cycle:

[0089] Coulomb efficiency (%) = C 充电 / C 放电 ×100%, where C 充电 For stripping capacity, C 放电 This represents the deposition capacity.

[0090] 2. Electrolyte Oxidation Voltage Test Method

[0091] Battery assembly: In a glove box, using lithium metal as the negative electrode, Celgard 2500 porous polymer membrane as the separator, and Al as the positive electrode, assemble a Li||Al coin cell and let it stand for 6 hours to allow the electrodes to be fully wetted.

[0092] Using an electrochemical workstation, the linear scanning voltammetry method was used in an environment of 25°C, with the scan rate set to 0.1 mV / s and the voltage range set to open circuit voltage to 6.0 V.

[0093] 3. Charge-discharge cycle performance test method (Li||NCM811 battery)

[0094] Preparation of NCM811 cathode: The active material (NCM811), conductive carbon black (Super P), and binder (PVDF) are mixed in a mass ratio of 80:10:10. After adding N-methylpyrrolidone, the resulting uniform slurry is coated onto an aluminum foil current collector, dried at 80 ºC, and then cut into sheets.

[0095] Battery assembly: In a glove box, Li||NCM811 coin cells were assembled using lithium metal as the negative electrode, Celgard 2500 porous polymer membrane as the separator, and NCM811 as the positive electrode. The cells were left to stand for 6 hours to allow the electrodes to be fully wetted.

[0096] Using a battery testing system, the test was conducted in a constant temperature chamber at 25°C. Constant current charge-discharge cycles were performed at a 1C rate, with the charging cut-off voltage set to 4.4, 4.5, 4.6, or 4.7 V and the discharging cut-off voltage set to 2.8 V. After a certain number of cycles, the discharge capacity of the first cycle and the discharge capacity of the Nth cycle were recorded. The capacity retention rate after N cycles was calculated using the following formula.

[0097] Formula for calculating capacity retention:

[0098] Capacity retention rate (%) = C N / C 首圈 ×100%; where C N This represents the discharge capacity during the Nth cycle.

[0099] The test results for each embodiment and comparative example are shown in Tables 1 and 2 below.

[0100] Table 1. Capacity retention rate under different charging cut-off voltages during cycling

[0101] Group 4.4 V / 500 revolutions 4.5 V / 300 revolutions 4.6 V / 200 revolutions 4.7 V / 200 revolutions Example 1 78.6% 75.8% 80.3% 76.5% Example 2 70.3% 72.1% 75.2% 70.1% Example 3 74.5% 74.6% 70.5% 73.2% Example 4 80.1% 76.2% 83.2% 77.6% Comparative Example 1 28.6% 15.8% 33.3% 32.8% Comparative Example 2 50.5% 49.8% 60.1% 53.3%

[0102] Table 2. Lithium deposition / stripping coulombic efficiency and oxidation voltage

[0103] Group Lithium deposition / stripping coulombic efficiency Oxidation voltage Example 1 98.3% 5.5 V Example 2 98.5% 5.2 V Example 3 98.0% 5.6 V Example 4 98.2% 5.5 V Comparative Example 1 73.5% 4.2 V Comparative Example 2 93.6% 5.0 V

[0104] From Table 1, Table 2 and Figure 1-5 It can be seen that, compared with the comparative example, Example 1 of the present invention has a higher lithium deposition / stripping coulombic efficiency, a denser lithium deposition morphology, and a higher cycle capacity retention; Figures 1 to 3 A comparison of SEM images (magnified 5000x) shows that the chloride electrolyte of this invention can achieve a denser, dendrite-free deposition morphology, indicating the excellent anti-lithium dendrite ability of the chloride electrolyte of this invention; from Figure 4It can be seen that the chloride electrolyte of Example 1 of the present invention significantly improves the lithium deposition / stripping coulombic efficiency to 98.3%, suppresses irreversible loss, and extends the cycle life of the lithium metal anode; Figure 5 It can be seen that the oxidation voltage of the chlorination electrolyte in Example 1 of the present invention is 5.5 V, indicating that the chlorination electrolyte has excellent antioxidant capacity.

[0105] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A chloride electrolyte for use in high-voltage lithium metal batteries, characterized in that, It includes lithium salt, solvent, and additives; the solvent is composed of chlorinated linear carbonate and dichloroalkanes, the chlorinated linear carbonate having a general structural formula as shown in formula (1): (1)； Wherein, R is an alkyl group having 1 to 4 carbon atoms; The dichloroalkane has a general structural formula as shown in formula (2): (2)； Where n is an integer from 1 to 7.

2. The chlorination electrolyte according to claim 1, characterized in that, The chlorolinear carbonate is at least one of chloromethyl carbonate, ...

3. The chlorination electrolyte according to claim 1, characterized in that, The dichloroalkane is at least one selected from 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,7-dichloroheptane, and 1,8-dichlorooctane.

4. The chlorination electrolyte according to claim 1, characterized in that, In the solvent, the volume ratio of the chlorinated linear carbonate to the dichloroalkanes is 1:(0.5~3).

5. The chlorination electrolyte according to claim 1, characterized in that, The additive is a fluorocyclic carbonate.

6. The chlorination electrolyte according to claim 5, characterized in that, The fluorocyclic carbonate is at least one of fluoroethylene carbonate and difluoroethylene carbonate.

7. The chlorination electrolyte according to claim 1, characterized in that, In the chlorinated electrolyte, the volume ratio of the additive to the solvent is (0.01~0.1):

1.

8. The chlorination electrolyte according to claim 1, characterized in that, The lithium salt is at least one of lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(pentafluoroethanesulfonyl)imide.

9. The chlorination electrolyte according to claim 1, characterized in that, In the chlorinated electrolyte, the concentration of the lithium salt is 0.5~2 mol / L.

10. An electrochemical device, characterized in that, include: Positive electrode, separator, negative electrode, and the chloride electrolyte according to any one of claims 1-9.

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