Electrolyte, battery and electric device

Abstract

The embodiment of the invention provides an electrolyte, a battery and a power utilization device, the electrolyte comprises an electrolyte salt, a solvent and a diluent, the diluent comprises a non-coordination diluent and a coordination diluent, the non-coordination diluent is a compound which is not complexed with cations in the electrolyte salt, and the coordination diluent is a compound which is not complexed with cations in the electrolyte salt. The coordination diluent is a compound which can be complexed with cations in the electrolyte salt. Through the synergistic effect of the non-coordination diluent and the coordination diluent, the anion decomposition rate can be increased to form a weak solvation layer and adjust a solvation cluster, and a stable electrolyte interface layer with a micelle-shaped structure is formed, so that the stability of an electrode / electrolyte interface is further enhanced, and the dendritic crystal growth problem is effectively inhibited; and the cycling stability and safety of the battery cell are improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrolyte, a battery, and an electrical device. Background Technology

[0002] Lithium-ion batteries are widely used in many fields, but their energy density is limited by graphite-based anodes. High-voltage lithium metal batteries are a strong candidate for high-energy-density batteries, but lithium metal batteries face problems such as electrode-electrolyte interphase instability and cycle capacity loss.

[0003] High-concentration electrolytes reduce free solvent molecules and enhance antioxidant stability by forming aggregates and contact ion pair clusters, which is beneficial for the decomposition of salt anions into inorganic substances in the SEI. However, the practical application of high-concentration electrolytes is limited by high cost, high viscosity, poor ionic conductivity and poor wettability. Local high-concentration electrolytes combined with high-concentration electrolytes and diluents overcome these limitations, but existing local ultra-concentrated electrolytes limit the ionic conductivity and ion transport number of the electrolyte, reducing the cycle performance of the battery.

[0004] Therefore, there is an urgent need to develop an electrolyte that can enhance the stability of the electrode-electrolyte interface and has high ionic conductivity. Summary of the Invention

[0005] This application provides an electrolyte, a battery, and an electrical device, aiming to improve the interfacial stability and ionic conductivity of existing electrolytes.

[0006] In a first aspect, this application provides an electrolyte comprising an electrolyte salt, a solvent, and a diluent, wherein the diluent comprises a non-coordinated diluent and a coordinated diluent, wherein the non-coordinated diluent is a compound that does not complex with cations in the electrolyte salt, and the coordinated diluent is a compound that can complex with cations in the electrolyte salt.

[0007] In this application, taking lithium salt as an example, the coordinating diluent forms dynamic coordination with lithium ions, participating in the lithium-ion solvation process without excessively interfering with lithium-ion transport. This promotes lithium-ion hopping conduction, increases ionic conductivity, reduces the coordination ability of solvent molecules, and accelerates ion migration kinetics, enabling the battery to maintain good charge-discharge performance even at high rates. Simultaneously, it reduces the coordination ability between Li⁺ and anions, causing the anions to decompose and form an SEI rich in inorganic compounds, constructing a stable interface, significantly improving the coulombic efficiency of the lithium metal anode, and broadening the electrochemical window.

[0008] Non-coordinating diluents do not dissolve lithium salts but are miscible with solvents. They do not coordinate with cations but exhibit dipole-dipole interactions, forming anion-rich solvation structures that can modulate the Li-salt composition. +The binding strength and topology of the solvent can effectively reduce the viscosity of the electrolyte, improve wettability, and make it easier for the electrolyte to wet the electrodes and separator, thereby improving the overall performance of the battery.

[0009] In summary, the synergistic effect of non-coordinated and coordinated diluents facilitates the formation of a weakly solvated layer and regulates solvated clusters, resulting in a stable micellar electrolyte interface layer. This further enhances the stability of the electrode / electrolyte interface, effectively suppresses dendrite growth, and improves the cycle stability and safety of the battery cell. Simultaneously, the synergistic effect of non-coordinated and coordinated diluents not only optimizes the electrolyte's microstructure but also improves its macroscopic properties, enabling the electrolyte to maintain good performance over a wider temperature range. Especially at low temperatures, the low viscosity and high wettability of the electrolyte significantly improve battery performance. Furthermore, the electrolyte of this application, while ensuring high rate and high voltage performance, also reduces electrolyte costs, improves battery safety and economy, and provides strong support for the development of high-performance, low-cost battery systems.

[0010] Optionally, with the electrolyte content being 100%, the mass content of the diluent is 10%-65%. By controlling the content of the diluent in the electrolyte, the amount of anion decomposition in the electrolyte salt is controlled, promoting the formation of an SEI film rich in inorganic compounds and improving the stability of the electrode / electrolyte interface. When the diluent content is below 10%, a stable micellar electrolyte interface layer cannot be formed, resulting in insufficient interface stability; when the diluent content exceeds 65%, the electrolyte viscosity is too low, the interaction between the solvent and the electrolyte salt is weakened, the solvated sheath layer is prone to disintegration, leading to a decrease in ionic conductivity and a weakening of interface protection capability.

[0011] Optionally, the mass ratio of the non-coordinating diluent to the coordinating diluent is 1 / 9-9. The non-coordinating diluent itself has extremely weak binding ability for electrolyte cations, effectively reducing the viscosity of the electrolyte solution and thus providing a more relaxed channel for the rapid migration of electrolyte cations. However, when the content of the non-coordinating diluent is too high, because it does not participate in the formation of the solvated sheath, it hinders the jumping conduction of cations, leading to a decrease in the ionic conductivity of the electrolyte and a decrease in the stability of the electrolyte.

[0012] When the content of the coordinating diluent is too high, the coordinating diluent will excessively complex with the electrolyte cations, resulting in an increase in electrolyte viscosity and a decrease in ionic conductivity.

[0013] By adjusting the mass ratio of non-coordinated diluent to coordinated diluent within the above range, the coordinated diluent improves the ionic conductivity of the electrolyte by participating in the solvation structure, while the non-coordinated diluent adjusts the Li... +The binding strength and topology of the solvent can effectively reduce the viscosity of the electrolyte, improve wettability, and make it easier for the electrolyte to wet the electrodes and separator, thereby improving the overall performance of the battery.

[0014] Optionally, the mass ratio of the non-coordinating diluent to the coordinating diluent is 1 / 5 to 5.

[0015] By adjusting the mass ratio of non-coordinated diluent to coordinated diluent within the above range, a stable micellar electrolyte interface layer is formed. Electrolyte salt cations can be transported more efficiently between the electrode and the electrolyte interface, reducing energy loss and resistance during ion transport. The stable electrolyte interface layer reduces irreversible side reactions, thereby significantly improving coulombic efficiency.

[0016] Optionally, the noncoordinating diluent includes at least one selected from 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, perfluorononenyl trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, 2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl methyl ether, and fluorobenzene.

[0017] By selecting the above-mentioned fluorinated ether or fluorobenzene non-coordinating diluents, which are miscible with the solvent, the viscosity of the electrolyte is effectively reduced, the wettability is improved, and the electrolyte is made to more easily wet the electrodes and separator, thereby improving the overall performance of the battery.

[0018] Optionally, the coordinating diluent includes at least one selected from bis(2,2,2-trifluoroethoxy)methane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, and hexafluoroisopropyl methyl ether. By selecting the above-mentioned coordinating diluent to form dynamic coordination with electrolyte cations, a stable electrolyte structure is formed between the electrode and electrolyte interface, while avoiding excessive binding of cations. This allows the cations complexed by the coordinating diluent to be transported between the electrode and electrolyte interface under the action of the non-coordinating diluent, thereby improving the ionic conductivity and ion transport number of the electrolyte.

[0019] Optionally, the solvent includes at least one of ether solvents, carbonate solvents, and phosphate solvents; And / or, the electrolyte salt includes a lithium salt, which includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide, and lithium fluorosulfonyl-perfluorobutylsulfonylimide.

[0020] By selecting the above-mentioned solvents, the solvation structure formed by them and lithium salts effectively improves the oxidation stability of the electrolyte, which is conducive to the formation of stable SEI and CEI, and improves the safety performance and cycle performance of the battery at high voltage.

[0021] Optionally, with the electrolyte content being 100%, the mass content of the electrolyte salt is 10%-50%, and the mass content of the solvent is 15%-65%.

[0022] By limiting the content of electrolyte salt and solvent within the above range, the electrolyte system is made into a locally high-concentration electrolyte. Adding non-coordinating diluent and coordinating diluent to the above locally high-concentration electrolyte allows the special solvation sheath formed by the cations and solvent in the electrolyte to not excessively interfere with the transport of lithium ions, which helps to maintain the high ionic conductivity of the electrolyte.

[0023] Secondly, this application provides a battery including the electrolyte described above. The battery can be a liquid-state laminated battery, a liquid-state wound battery, a liquid-state cylindrical battery, a semi-solid-state laminated battery, a semi-solid-state wound battery, or a semi-solid-state cylindrical battery. By selecting the above-mentioned electrolyte with high ionic conductivity, it is beneficial to improve the battery's cycle performance and safety.

[0024] Thirdly, this application provides an electrical device including the battery described above. By using the battery described above, which has good cycle performance and safety performance, the battery life and safety of the electrical device are improved. Attached Figure Description

[0025] Figure 1 This is a charge-discharge curve diagram of a battery at different rates provided in Embodiment 1 of this application; Figure 2 This is a charge-discharge curve of a battery at different rates, provided in Comparative Example 1 of this application; Figure 3 This is a charge / discharge efficiency curve of a battery at 0.2C provided in Embodiment 1 of this application; Figure 4 This is a charge / discharge efficiency curve of a battery at 0.2C provided in Comparative Example 1 of this application. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] One embodiment of this application provides an electrolyte comprising an electrolyte salt, a solvent, and a diluent, wherein the diluent comprises a noncoordinate diluent and a coordinate diluent, wherein the noncoordinate diluent is a compound that does not complex with cations in the electrolyte salt, and the coordinate diluent is a compound that can complex with cations in the electrolyte salt.

[0028] In this application, taking lithium salt as an example, the coordinating diluent forms dynamic coordination with lithium ions, participating in the lithium-ion solvation process without excessively interfering with lithium-ion transport. This promotes lithium-ion hopping conduction, increases ionic conductivity, reduces the coordination ability of solvent molecules, and accelerates ion migration kinetics, enabling the battery to maintain good charge-discharge performance even at high rates. Simultaneously, it reduces the coordination ability between Li⁺ and anions, causing the anions to decompose and form an SEI rich in inorganic compounds, constructing a stable interface, significantly improving the coulombic efficiency of the lithium metal anode, and broadening the electrochemical window.

[0029] Non-coordinating diluents do not dissolve lithium salts but are miscible with solvents. They do not coordinate with cations but exhibit dipole-dipole interactions, forming anion-rich solvation structures that can modulate the Li-salt composition. + The binding strength and topology of the solvent can effectively reduce the viscosity of the electrolyte, improve wettability, and make it easier for the electrolyte to wet the electrodes and separator, thereby improving the overall performance of the battery.

[0030] In summary, the synergistic effect of non-coordinated and coordinated diluents facilitates the formation of a weakly solvated layer and regulates solvated clusters, resulting in a stable micellar electrolyte interface layer. This further enhances the stability of the electrode / electrolyte interface, effectively suppresses dendrite growth, and improves the cycle stability and safety of the battery cell. Simultaneously, the synergistic effect of non-coordinated and coordinated diluents not only optimizes the electrolyte's microstructure but also improves its macroscopic properties, enabling the electrolyte to maintain good performance over a wider temperature range. Especially at low temperatures, the low viscosity and high wettability of the electrolyte significantly improve battery performance. Furthermore, the electrolyte of this application, while ensuring high rate and high voltage performance, also reduces electrolyte costs, improves battery safety and economy, and provides strong support for the development of high-performance, low-cost battery systems.

[0031] In one embodiment, with the electrolyte content being 100%, the mass content of the diluent is 10%-65%.

[0032] By controlling the content of diluent in the electrolyte, the amount of anion decomposition in the electrolyte salt can be controlled, promoting the formation of an inorganic compound-rich SEI film and improving the stability of the electrode / electrolyte interface. When the diluent content is below 10%, a stable micellar electrolyte interface layer cannot be formed, resulting in insufficient interface stability. When the diluent content exceeds 65%, the electrolyte viscosity is too low, the interaction between the solvent and the electrolyte salt is weakened, the solvated sheath layer is prone to disintegration, leading to a decrease in ionic conductivity and a weakened interface protection capability.

[0033] Specifically, the mass content of the diluent includes, but is not limited to, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, or 65%.

[0034] In one embodiment, the mass ratio of the non-coordinating diluent to the coordinating diluent is 1 / 9-9.

[0035] Non-coordinating diluents have extremely weak binding capacity for electrolyte cations. They can effectively reduce the viscosity of electrolyte solutions, thus providing a more relaxed channel for the rapid migration of electrolyte cations. However, when the content of non-coordinating diluents is too high, because they do not participate in the formation of the solvated sheath, they hinder the jumping conduction of cations, leading to a decrease in the ionic conductivity of the electrolyte and a decrease in the stability of the electrolyte.

[0036] When the content of the coordinating diluent is too high, the coordinating diluent will excessively complex with the electrolyte cations, resulting in an increase in electrolyte viscosity and a decrease in ionic conductivity.

[0037] By adjusting the mass ratio of non-coordinated diluent to coordinated diluent within the above range, the coordinated diluent improves the ionic conductivity of the electrolyte by participating in the solvation structure, while the non-coordinated diluent adjusts the Li... + The binding strength and topology of the solvent can effectively reduce the viscosity of the electrolyte, improve wettability, and make it easier for the electrolyte to wet the electrodes and separator, thereby improving the overall performance of the battery.

[0038] Specifically, the mass ratio of non-coordinating diluent to coordinating diluent includes, but is not limited to, 1:9, 1:7, 1:5, 1:3, 2:8, 2:5, 3:7, 3:4, 4:6, 4:3, 5:5, 5:3, 5:1, 6:4, 6:1, 7:3, 8:2, or 9:1.

[0039] In a preferred embodiment, the mass ratio of the non-coordinating diluent to the coordinating diluent is 1 / 5-5. By controlling the mass ratio of the non-coordinating diluent to the coordinating diluent within the above range, a stable micellar electrolyte interface layer is formed. Electrolyte salt cations can be transported more efficiently between the electrode and the electrolyte interface, reducing energy loss and resistance during ion transport. The stable electrolyte interface layer reduces the occurrence of irreversible side reactions, thereby significantly improving coulombic efficiency.

[0040] In one embodiment, the noncoordinating diluent includes at least one of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, perfluorononenyl trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, 2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl methyl ether, and fluorobenzene (FB). By selecting the above-mentioned fluorinated ether or fluorobenzene noncoordinating diluents, which are miscible with the solvent, the viscosity of the electrolyte is effectively reduced, the wettability is improved, and the electrolyte is made easier to wet the electrodes and separator, thereby improving the overall performance of the battery.

[0041] In one embodiment, the coordinating diluent includes at least one of bis(2,2,2-trifluoroethoxy)methane (BTFM), 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane (BTFEE), and hexafluoroisopropyl methyl ether (HFME). By selecting the above-mentioned coordinating diluent to form dynamic coordination with electrolyte cations, a stable electrolyte structure is formed at the electrode-electrolyte interface, while avoiding excessive binding of cations. This allows the cations complexed by the coordinating diluent to be transported between the electrode and electrolyte interface under the action of the non-coordinating diluent, thereby improving the ionic conductivity and ion transport number of the electrolyte.

[0042] In one embodiment, the solvent includes at least one of ether solvents, carbonate solvents, and phosphate ester solvents. By selecting the above solvents, the solvation structure formed with the electrolyte salt effectively improves the oxidation stability of the electrolyte, which is beneficial for the formation of stable SEI and CEI, thereby improving the battery's safety performance and cycle performance at high voltages.

[0043] In one embodiment, the ether solvent includes at least one selected from ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, ethylene glycol dibutyl ether (EGBE), triethylene glycol dimethyl ether (G3), tetrahydrofuran (THF), and dioxolane (DOL); the lone pair electrons of the oxygen atom in the ether solvent interact with Li+ The strong coordination ability of the ether solvent forms a tight solvated sheath layer, resulting in excellent interfacial stability between the electrolyte and the electrode. Simultaneously, the low viscosity and high dielectric constant of the ether solvent enhance the low-temperature ion transport capability of the electrolyte.

[0044] And / or, the carbonate solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dimethyl 2,5-dioxadiazine (DMDOHD); the carbonate solvent coordinates with lithium ions to form ion aggregates, which can form a locally high-concentration electrolyte and enhance the antioxidant stability of the electrolyte.

[0045] And / or, the phosphate ester solvent includes at least one of triethyl phosphate (TEP), trimethyl phosphate (TMP), triethyl phosphite (TEP), dibutyl phosphate (DBP), triphenyl phosphate (TPP), triethyl phosphite (TEPi), tributyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl)methyl phosphate, trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite, dimethyl methylphosphonate, diethyl ethylphosphonate, diethyl phenylphosphonate, and bis(2,2,2-trifluoroethyl)methylphosphonate. The phosphate ester solvent promotes the formation of a LiF and Li3PO4-rich CEI film in the electrolyte under high voltage, inhibits transition metal dissolution, and further improves the cycle performance of the battery.

[0046] In one embodiment, the electrolyte salt comprises a lithium salt, which includes at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide (LiTNFSI), and lithium fluorosulfonyl-perfluorobutylsulfonylimide (LiFNFSI).

[0047] In one embodiment, with the electrolyte content being 100%, the mass content of the electrolyte salt is 10%-50%, and the mass content of the solvent is 15%-65%. By limiting the content of the electrolyte salt and solvent within the above ranges, the electrolyte system is made into a locally high-concentration electrolyte. The addition of non-coordination diluents and coordination diluents to the above locally high-concentration electrolyte allows the special solvation sheath formed by the cations and solvent in the electrolyte to not excessively interfere with the transport of lithium ions, thus helping to maintain the high ionic conductivity of the electrolyte.

[0048] Specifically, the mass content of the electrolyte salt includes, but is not limited to, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. The mass content of the solvent includes, but is not limited to, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, or 65%.

[0049] In one embodiment, the electrolyte further includes additives, which include at least one of lithium nitrate (LiNO3), lithium difluorooxalate borate (LiDFOB), lithium difluorophosphate, lithium bis(oxalate borate), fluoroethylene carbonate (FEC), trimethyl phosphate, vinyl sulfate, vinylene carbonate, dimethyl dimethoxysilane (DMMS), tris(trimethylsilyl) phosphate, tris(2,2,2'-trifluoroethyl) phosphite, and trifluoroacetate. By adding the above additives, gas production in the electrolyte is suppressed, side reactions in the electrolyte are reduced, uniform deposition of lithium ions is effectively promoted, the lithium ion transport rate and flame retardant properties are improved, and the problem of lithium dendrite formation is solved.

[0050] In one embodiment, with the electrolyte content being 100%, the mass content of the additive is 0.1%-10%. By controlling the mass content of the additive within the above range, a thin and stable interface film can be formed on the electrode surface by the electrolyte, thereby improving the cycle performance of the battery.

[0051] The mass content of the additives includes, but is not limited to, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0052] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0053] One embodiment of this application provides a battery including the electrolyte as described above. It should be noted that the battery can be a stacked, wound, or cylindrical battery. Specifically, the battery can be a liquid battery, a semi-solid battery, or a solid battery.

[0054] In one embodiment, the battery further includes a positive electrode, a negative electrode, and a separator. The separator is made of at least one material selected from polypropylene (PP), polyethylene (PE), PP / PE / PP composite material, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ceramic separator, ceramic polyamide (PI), aramid (AF), and nonwoven fabric.

[0055] The cathode includes at least one of lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel oxide (LNO), ternary materials (NCM, NCA), lithium-rich manganese-based (LMR), lithium nickel manganese oxide (LNMO), and lithium vanadium oxide phosphate (Li3V2(PO4)3, LiVOPO4).

[0056] The anode includes one of the following: graphite anode, silicon-oxygen anode, silicon-carbon anode, silicon anode, tin anode, tin oxide anode, tin alloy anode (Sn-Fe, Sn-Co, Sn-Cu), lithium metal anode, lithium alloy anode (Li-Ag, Li-Al, Li-Sn, Li-Mg, Li-Zn, Li-In, Li-Ga), and lithium-free anode.

[0057] In one embodiment, when the battery is a semi-solid battery, the amount of electrolyte added is 0.5%-50% of the total mass of the positive electrode active material layer.

[0058] Semi-solid batteries include gel electrolytes or solid electrolytes, with the solid electrolyte selected from inorganic solid electrolytes, polymer solid electrolytes, and composite solid electrolytes. Inorganic solid electrolytes include at least one of oxide solid electrolytes, sulfide solid electrolytes, and halide electrolytes. Composite solid electrolytes include both inorganic solid electrolytes and polymer solid electrolytes.

[0059] One embodiment of this application provides an electrical device including the battery described above. Exemplary examples include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, aircraft, and robots.

[0060] The present application will be further illustrated by the following examples.

[0061] Example 1 This embodiment illustrates the electrolyte and battery disclosed in this application, and includes the following operational steps: 1. Electrolyte The electrolyte consists of 14.5% lithium salt LiFSI, 20% organic solvent DME, 35% non-coordinating diluent TTE, 30% coordinating diluent BTFEE, and 0.5% additive LiNO3.

[0062] 2. Preparation of the positive electrode A positive electrode slurry was prepared by uniformly mixing lithium nickel cobalt manganese oxide ternary material LiNi9CoMnO2, conductive agent SuperP, binder PVDF and carbon nanotubes (CNT) in a mass ratio of 96.5:2.5:1.0:0.5. The slurry was coated onto aluminum foil for current collector, dried at 85°C and then cold-pressed. After trimming, cutting and slitting, the positive electrode sheet was dried at 85°C for 8 hours under vacuum to form a positive electrode sheet.

[0063] 3. Negative electrode plate The negative electrode is a lithium metal negative electrode.

[0064] 4. Battery manufacturing A separator is placed between the electrolyte and the negative electrode prepared above. Then, the sandwich structure consisting of the electrolyte, the negative electrode and the separator is stacked and encapsulated with an aluminum-plastic film. After electrolyte injection and formation, a battery is obtained.

[0065] Example 2-15 Examples 2-15 illustrate the electrolyte and battery disclosed in this application, including most of the operating steps in Example 1 above, except that the formulation in Table 1 is used.

[0066] Comparative Examples 1-2 Comparative Examples 1-2 are used to illustrate the electrolyte and battery disclosed in this application, including most of the operating steps in Example 1, except that they use the formulation in Table 1.

[0067] Table 1 Performance testing I. The electrolytes and batteries obtained in the above embodiments and comparative examples were subjected to the following performance tests: 1. Electrolyte oxidation potential test: The oxidation potential of the electrolyte was tested using the linear scanning potentiometric method with an EC-Lab electrochemical workstation. The test voltage range was 2.5-6V, and the scan rate was 1 mV·s. -1 The method uses a device structure of "stainless steel sheet | diaphragm | lithium sheet" for testing, with the stainless steel sheet as the working electrode and the lithium sheet as the reference electrode.

[0068] 2. Cyclic test: Cyclic charge and discharge test is conducted at a voltage range of 3.0V-4.3V, a temperature of 25℃, and a charge / discharge rate of 0.2C / 0.5D. The capacity retention rate and the average charge and discharge efficiency of the battery are recorded after 100 cycles.

[0069] The test results are shown in Table 2.

[0070] Table 2 As can be seen from the test results of Examples 1-15 and Comparative Examples 1-2 in Table 2, the synergistic effect of non-coordinated diluent and coordinated diluent can significantly optimize the solvation structure and interfacial behavior of the electrolyte, effectively suppress dendrite growth of lithium metal anode and improve cycle stability.

[0071] The test results of Examples 4 and 7-9 show that when the content of diluent in the electrolyte is in the range of 10%-65%, the electrolyte has a high oxidation potential, while the battery has high discharge efficiency and capacity retention. The test results of Examples 4 and 10-15 show that when the proportion of coordinating diluent in the diluent decreases, the battery's discharge efficiency and capacity retention decrease.

[0072] In locally concentrated electrolyte systems, a synergistic strategy of using both non-coordinated and coordinated diluents can significantly optimize the solvation structure and interfacial behavior of the electrolyte, effectively suppressing dendrite growth in the lithium metal anode and improving cycle stability. The non-coordinated diluent hardly participates in the lithium-ion solvation sheath, primarily reducing system viscosity and cost while maintaining a high proportion of contact ion pairs (CIPs) and aggregates (AGGs) in the concentrated "mother liquor." This structure is rich in anions (such as FSI⁻ and TFSI⁻) and has very few free solvent molecules. The coordinated diluent, on the other hand, slightly participates in coordination, moderately weakening the strong binding energy between lithium ions and the main solvent, increasing the lithium-ion transference number, and slightly loosening the solvation sheath layer. The synergistic effect of the two promotes the preferential, rapid and uniform decomposition of anions at the negative electrode interface, accelerating the formation of a dense and stable solid electrolyte interphase (SEI) film rich in inorganic lithium salts (such as LiF and Li3N). On the other hand, they jointly enhance the "weak solvation" environment, reduce the lithium-ion desolvation energy barrier, and encourage lithium ions to follow the instantaneous nucleation-lateral growth mode during deposition, forming dense bulk lithium deposits rather than dendrites. The precise synergy between the two is the key to achieving high ion conductivity, rapid interfacial film formation kinetics, stable SEI and dendrite-free lithium deposition, which significantly exceeds the performance boundaries of a single diluent system and provides an ideal electrolyte solution for high energy density lithium metal batteries.

[0073] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates an "or" relationship between the related objects if preceded and followed by text. If preceded and followed by numbers, it indicates a ratio relationship between the related objects.

[0074] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An electrolyte, characterized in that, The solution includes an electrolyte salt, a solvent, and a diluent, wherein the diluent includes a non-coordinate diluent and a coordinate diluent, wherein the non-coordinate diluent is a compound that does not complex with the cations in the electrolyte salt, and the coordinate diluent is a compound that can complex with the cations in the electrolyte salt.

2. The electrolyte according to claim 1, characterized in that, With the electrolyte content being 100%, the mass content of the diluent is 10%-65%.

3. The electrolyte according to claim 1, characterized in that, The mass ratio of the non-coordinating diluent to the coordinating diluent is 1 / 9-9.

4. The electrolyte according to claim 3, characterized in that, The mass ratio of the non-coordinating diluent to the coordinating diluent is 1 / 5-5.

5. The electrolyte according to claim 1, characterized in that, The noncoordinate diluent includes at least one selected from 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, perfluorononenyl trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, 2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl methyl ether, and fluorobenzene.

6. The electrolyte according to claim 1, characterized in that, The coordinating diluent includes at least one of bis(2,2,2-trifluoroethoxy)methane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, and hexafluoroisopropyl methyl ether.

7. The electrolyte according to claim 1, characterized in that, The solvent includes at least one of ether solvents, carbonate solvents, and phosphate solvents; And / or, the electrolyte salt includes a lithium salt, which includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide, and lithium fluorosulfonyl-perfluorobutylsulfonylimide.

8. The electrolyte according to claim 1, characterized in that, With the electrolyte content being 100%, the mass content of the electrolyte salt is 10%-50%, and the mass content of the solvent is 15%-65%.

9. A battery, characterized in that, Includes the electrolyte as described in any one of claims 1-8.

10. An electrical appliance, characterized in that, Includes the battery as described in claim 9.

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