High-voltage electrolyte and application thereof in lithium ion battery
By introducing main and synergistic additives with specific structures into lithium-ion batteries, a dense solid electrolyte interface film is constructed, which solves the problems of electrolyte stability and interface compatibility under high voltage and improves the cycle stability and energy density of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-15
- Publication Date
- 2026-03-24
AI Technical Summary
Existing lithium-ion batteries suffer from insufficient chemical and electrochemical stability of electrolytes under high voltage, poor electrode/electrolyte interface compatibility, and deteriorated interfacial kinetics. Traditional additive strategies have limited effectiveness and cannot effectively construct stable interfacial films, leading to battery performance degradation and safety hazards.
By employing main additives and synergistic additives with specific structures, a dense and uniform solid electrolyte interface film is preferentially formed on the positive electrode surface. The interface film is constructed through the oxidative decomposition of the main additives, and the composition and stability of the film are optimized through the synergistic additives, thus forming a highly efficient multi-level electrode/electrolyte interface optimization system.
It significantly improves the chemical and electrochemical stability of the battery under high voltage, reduces interfacial impedance, improves lithium-ion transport efficiency, extends battery cycle life, enhances energy density and rate performance, suppresses side reactions, and forms a highly adaptable interfacial film.
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Figure CN121726535A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrolyte technology, and in particular to a high-voltage electrolyte and its application in lithium-ion batteries. Background Technology
[0002] Lithium-ion batteries, as highly efficient energy storage devices, have been widely used in portable electronic devices, electric vehicles, and large-scale energy storage systems. With the continuous increase in energy density requirements from various applications, there is a growing demand for batteries with higher operating voltages (typically referring to a charging cut-off voltage ≥ 4.5 V vs. Li / Li). + Battery systems that utilize high-nickel layered oxides (such as NCM811) and lithium cobalt oxide have become an important technological direction. Increasing the charging voltage can directly improve the actual reversible capacity of high-specific-capacity cathode materials such as high-nickel layered oxides (such as NCM811) and lithium cobalt oxide, thereby significantly increasing the energy density of the battery.
[0003] However, conventional electrolyte systems face severe challenges when batteries operate at high voltages, which seriously hinders the commercialization of high-voltage lithium-ion batteries. Existing technologies mainly suffer from the following problems:
[0004] 1. The electrolyte lacks sufficient chemical and electrochemical stability at high voltages. Conventional electrolytes mainly consist of carbonate organic solvents (such as ethylene carbonate EC, dimethyl carbonate DMC, etc.) and lithium hexafluorophosphate (LiPF6) salts, whose electrochemical stability window is typically below 4.3 V (vs. Li / Li). + At higher potentials, electrolyte components readily undergo irreversible oxidative decomposition on the positive electrode surface. This process not only consumes active lithium and electrolyte but also forms a heterogeneous and unstable positive electrode electrolyte interphase (CEI) film composed of organic matter and inorganic lithium salts on the positive electrode surface. This film has a porous structure and poor mechanical properties, failing to effectively prevent the continuous decomposition of the electrolyte. This leads to a continuous increase in interfacial impedance, rising internal resistance of the battery, accelerated capacity decay, and a significant reduction in cycle life.
[0005] 2. Poor compatibility at the electrode / electrolyte interface under high voltage leads to deteriorated interfacial kinetics. An unstable CEI film hinders normal lithium-ion transport at the interface, resulting in increased charge transfer impedance. Simultaneously, gases produced by the oxidative decomposition of the electrolyte (such as CO2 and olefins) may cause cell swelling, posing a safety hazard. Furthermore, under high-potential driving, transition metal ions (such as Ni...) 4+ Co 4+ It is easier for it to dissolve from the positive electrode lattice, migrate to the negative electrode and damage the solid electrolyte interphase (SEI) film of the negative electrode, triggering a chain of side reactions and further impairing the overall performance of the battery.
[0006] 3. Traditional additive strategies have limitations. To improve high-voltage performance, the industry often introduces various functional additives, such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to improve the SEI film on the negative electrode, and some phosphorus, boron, and sulfur-containing compounds to stabilize the positive electrode interface. However, many additives have limited protective effects under high voltage, or their decomposition products may increase interfacial impedance; some additives, while improving performance in one aspect, may negatively impact other properties (such as low-temperature characteristics and storage performance). Current technology lacks a highly efficient main additive that can preferentially and controllably participate in film formation under high voltage and form a CEI film with high ionic conductivity, excellent mechanical stability, and good electrochemical inertness.
[0007] Therefore, developing a high-voltage electrolyte that can effectively construct a stable electrode / electrolyte interface film under high voltage, reduce interface impedance, and enhance battery cycle stability has become a key issue that urgently needs to be addressed in the current lithium-ion battery technology field, and is of great practical significance for promoting the development of high-energy-density lithium-ion batteries. Summary of the Invention
[0008] The purpose of this invention is to address the problems in the prior art, such as insufficient chemical and electrochemical stability of existing electrolytes under high voltage, poor compatibility of the electrode / electrolyte interface under high voltage, and deterioration of interface kinetics, and to propose a high-voltage electrolyte and its application in lithium-ion batteries.
[0009] In a first aspect, this application provides a high-voltage electrolyte, comprising a lithium salt, an organic solvent, and a functional additive; the functional additive includes a main additive A and a synergistic additive B.
[0010] The main additive A is a compound having the structure shown in formula (I):
[0011] Formula (I)
[0012] Wherein, R is selected from C1-C6 alkyl, alkoxy, alkenyl or alkynyl groups, wherein the alkyl, alkoxy, alkenyl or alkynyl groups may optionally be substituted.
[0013] Optionally, the main additive A is selected from at least one of the following compounds:
[0014] Equation 1-1;
[0015] Equation 1-2;
[0016] Equation 1-3.
[0017] Optionally, the content of the main additive A is 0.1wt% to 5wt% based on the total mass of the electrolyte.
[0018] Optionally, the synergistic additive B is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalate borate, lithium difluorophosphate, and lithium bis(trifluoromethanesulfonyl)imide.
[0019] Optionally, based on the total mass of the electrolyte, the total content of the synergistic additive B is 0.1wt% to 5wt%.
[0020] Optionally, the lithium salt comprises lithium hexafluorophosphate.
[0021] Optionally, the concentration of lithium hexafluorophosphate in the electrolyte is 1.0 mol / L to 1.5 mol / L.
[0022] Optionally, the organic solvent is selected from one or more combinations of ethylene carbonate, propylene carbonate, butene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, vinylene carbonate, and vinyl sulfite.
[0023] Secondly, this application provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a high-voltage electrolyte as described in the first aspect.
[0024] Optionally, the charging cut-off voltage of the lithium-ion battery is not less than 4.5V.
[0025] Compared with the prior art, this application includes at least one of the following beneficial technical effects:
[0026] By introducing a master additive with a specific structure, the additive can preferentially construct the electrode / electrolyte interface film before the solvent oxidation and decomposition, effectively suppressing the violent decomposition of organic solvent molecules on the high-voltage positive electrode surface, thereby raising the practical oxidation potential window of the electrolyte to meet the requirements of charging voltage of 4.5V and above.
[0027] Through the combined action of the main additive and synergistic additives, a dense, uniform, and organic-inorganic hybrid solid electrolyte interfacial film can be formed in situ on the surface of the high-voltage cathode. This film exhibits excellent ionic conductivity and electronic insulation, effectively preventing direct contact between the electrolyte and the highly active cathode material, and significantly improving the chemical and electrochemical stability of the electrode / electrolyte interface. With the guarantee of a stable interfacial film, side reactions during high-voltage cycling are greatly suppressed, and cycle stability is significantly improved.
[0028] The interface film formed by this invention is not only stable, but also has low lithium-ion migration resistance, which ensures rapid transport of lithium ions at the interface under high voltage, reduces battery polarization, helps to realize the theoretical capacity of the cathode material under high voltage, and improves the energy density and rate performance of the battery.
[0029] By adjusting the structure of the main additive and its mass percentage in the electrolyte, the composition and properties of the interfacial film can be optimized for different cathode material systems and voltage requirements, thus achieving the designability of electrolyte performance.
[0030] In summary, this invention constructs a highly efficient multi-level electrode / electrolyte interface optimization system by introducing a main additive and a synergistic additive with specific structures. The main additive A preferentially undergoes oxidative decomposition before the electrolyte solvent, forming a dense interfacial film on the positive electrode surface, blocking direct contact and continuous oxidation by the electrolyte. The synergistic additive B further optimizes the composition and stability of the interfacial film through decomposition or reaction. The combined effect of the main and synergistic additives improves the battery's cycle performance under high voltage and effectively suppresses continuous side reactions under high voltage, resulting in higher capacity retention, lower polarization, and better interfacial stability during high-voltage long-cycle operation. Attached Figure Description
[0031] Figure 1 This is a comparison graph of the LSV (linear sweep voltammetry) of the electrolytes in Example 2 and Comparative Example 1 of the present invention.
[0032] Figure 2 This is a charge-discharge curve of the electrolyte in Example 2 of the present invention in a Li||NCM811 coin cell.
[0033] Figure 3 This is a charge-discharge curve of the electrolyte of Comparative Example 1 of the present invention in a Li||NCM811 coin cell.
[0034] Figure 4 This is a comparison of the EIS (electrochemical impedance spectroscopy) of the electrolytes of Example 2 and Comparative Example 1 after 100 cycles in a Li||NCM811 coin cell.
[0035] Figure 5 This is a graph showing the relationship between the number of cycles and capacity retention of the electrolytes of Example 2 and Comparative Example 1 in an NCM811|| Gr soft-pack battery. Detailed Implementation
[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.
[0037] Example 1
[0038] This embodiment provides a high-voltage electrolyte, the composition of which includes a main lithium salt, an organic solvent, and a high-voltage functional additive. The high-voltage functional additive includes a main additive and a synergistic additive. The main additive is shown in Formula 1-1:
[0039] Equation 1-1;
[0040] The high-voltage electrolyte is prepared by the following steps:
[0041] In an argon atmosphere glove box with moisture and oxygen levels both less than 0.1 ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and fluoroethylene carbonate (FEC) were mixed in a volume ratio of 3:4:2:1 as an organic solvent. The main lithium salt, lithium hexafluorophosphate (LiPF6), was added to the mixture to obtain a 1 mol / L lithium hexafluorophosphate (LiPF6) solution. The main additive shown in Formula 1-1 was added to the mixture at a dosage of 0.1 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution. Then, the synergistic additives lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluorooxalate borate (LiDFOB) were added, each at a dosage of 1 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, and the mixture was thoroughly mixed.
[0042] Example 2
[0043] This embodiment provides a high-voltage electrolyte, which comprises a main lithium salt, an organic solvent, and a high-voltage functional additive, wherein the high-voltage functional additive includes a main additive and a synergistic additive as shown in Formula 1-1.
[0044] The electrolyte differs from that in Example 1 in that the amount of the main additive is 0.5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, while the remaining steps and parameters remain the same.
[0045] Example 3
[0046] This embodiment provides a high-voltage electrolyte, which comprises a main lithium salt, an organic solvent, and a high-voltage functional additive, wherein the high-voltage functional additive includes a main additive and a synergistic additive as shown in Formula 1-1.
[0047] The electrolyte differs from that in Example 1 in that the amount of the main additive is 2.5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, while the remaining steps and parameters remain the same.
[0048] Example 4
[0049] This embodiment provides a high-voltage electrolyte, which comprises a main lithium salt, an organic solvent, and a high-voltage functional additive, wherein the high-voltage functional additive includes a main additive and a synergistic additive as shown in Formula 1-1.
[0050] The electrolyte differs from that in Example 1 in that the amount of the main additive is 5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, while the remaining steps and parameters remain the same.
[0051] Example 5
[0052] This embodiment provides a high-voltage electrolyte, the composition of which includes a main lithium salt, an organic solvent, and a high-voltage functional additive. The high-voltage functional additive includes a main additive and a synergistic additive. The main additive is shown in Formula 1-2.
[0053] Equation 1-2;
[0054] The high-voltage electrolyte is prepared by the following steps:
[0055] In an argon atmosphere glove box with moisture and oxygen levels both less than 0.1 ppm, ethylene carbonate (EC), fluoroethylene carbonate (FEC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:6 as an organic solvent. The main lithium salt, lithium hexafluorophosphate (LiPF6), was added to the mixture to obtain a lithium hexafluorophosphate (LiPF6) solution with a concentration of 1.2 mol / L. The main additive shown in Formula 1-2 was added to the mixture at a dosage of 0.5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution. Then, the synergistic additives lithium difluorophosphate (LiPO2F2) and lithium difluorooxalate borate (LiDFOB) were added, each at a dosage of 1 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, and the mixture was thoroughly mixed.
[0056] Example 6
[0057] This embodiment provides a high-voltage electrolyte, which comprises a main lithium salt, an organic solvent, and a high-voltage functional additive, wherein the high-voltage functional additive includes a main additive and a synergistic additive as shown in Formulas 1-2.
[0058] The electrolyte differs from that in Example 5 in that the amount of the main additive is 5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, while the remaining steps and parameters remain the same.
[0059] Example 7
[0060] This embodiment provides a high-voltage electrolyte, the composition of which includes a main lithium salt, an organic solvent, and a high-voltage functional additive. The high-voltage functional additive includes a main additive and a synergistic additive. The main additive is shown in Formulas 1-3.
[0061] Equation 1-3;
[0062] The high-voltage electrolyte is prepared by the following steps:
[0063] In an argon atmosphere glove box with moisture and oxygen levels both less than 0.1 ppm, ethylene carbonate (EC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC) were mixed in a volume ratio of 3:5:2 as an organic solvent. The main lithium salt, lithium hexafluorophosphate (LiPF6), was added to obtain a lithium hexafluorophosphate (LiPF6) solution with a concentration of 1.2 mol / L. The main additive shown in Formula 1-3 was added to the solution at an amount of 0.5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution. Then, the synergistic additives lithium difluorophosphate (LiPO2F2) and lithium dioxalate borate (LiBOB) were added at an amount of 1 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, and the mixture was thoroughly mixed.
[0064] Example 8
[0065] This embodiment provides a high-voltage electrolyte, which comprises a main lithium salt, an organic solvent, and a high-voltage functional additive, wherein the high-voltage functional additive includes a main additive and a synergistic additive as shown in Formulas 1-3.
[0066] The electrolyte in this example differs from that in Example 7 in that the amount of the main additive is 5 wt% of the total mass of the lithium hexafluorophosphate (LiPF6) solution, while the remaining steps and parameters remain the same.
[0067] Comparative Example 1
[0068] The difference between this comparative example and Example 1 is that no main additive as shown in Formula 1-1 is added.
[0069] Performance testing:
[0070] Electrolyte LSV testing: A three-electrode system was used, with a platinum electrode as the working electrode and lithium plates as the counter and reference electrodes. The scan rate was 1 mV / s, and the voltage range was 3.0 V to 6.0 V.
[0071] Li||NCM811 coin cell fabrication
[0072] (1) Positive electrode: LiNi 0.8 Co 0.1 Mn 0.1 O2, PVDF binder, and conductive carbon black are mixed in a mass ratio of 8:1:1 and dispersed in N-methyl-2-pyrrolidone (NMP). After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is uniformly coated onto an aluminum foil current collector, vacuum dried at 100°C, rolled, and then cut into 12 mm diameter discs using a punching machine.
[0073] (2) Lithium anode: A lithium metal sheet with a diameter of 16.0 mm and a thickness of 400 μm is used.
[0074] (3) Diaphragm: Celgard 2400 diaphragm with a diameter of 18 mm is used.
[0075] (4) Battery assembly: In an argon atmosphere glove box with moisture and oxygen less than 0.1 ppm, the batteries are assembled in the following order: negative electrode shell - stainless steel sheet - spring sheet - lithium sheet - separator - positive electrode sheet - positive electrode shell. The electrolytes from Examples 1-9 and Comparative Example 1 are added to assemble the CR2032 coin cell.
[0076] Li||NCM811 button cell charge / discharge test: Activation at 0.2C rate for 3 cycles, followed by 1C rate long cycle, constant current and constant voltage charging, and constant current discharging.
[0077] EIS testing: The Li||NCM811 coin cell battery was removed after 100 cycles and tested at a frequency range of 100kHz to 10mHz and a voltage range of -5.0V to 5.0V.
[0078] NCM811|| Gr soft-pack battery test: Electrolytes from Examples 1-9 and Comparative Example 1 were added to the soft-pack battery dry cell respectively. The electrolyte injection volume was 3.0 g / Ah. The charge-discharge range for electrochemical performance testing was 3V to 4.5V. The capacity retention rate of the battery after 100 cycles at 1C is shown in Table 1.
[0079] Table 1
[0080]
[0081] The LSV test comparison graphs of the electrolytes in Example 2 and Comparative Example 1 are shown below. Figure 1 As shown, the charge-discharge curves of the Li||NCM811 coin cells prepared with the electrolyte of Example 2 are as follows. Figure 2 As shown, the charge-discharge curves of the Li||NCM811 coin cells prepared with the electrolyte of Comparative Example 1 are as follows. Figure 3 As shown, the EIS comparison graphs of the Li||NCM811 coin cells prepared with the electrolytes of Example 2 and Comparative Example 1 after 100 cycles are as follows. Figure 4 As shown, the cycle life and capacity retention of the NCM811||Gr pouch cells prepared with the electrolytes of Example 2 and Comparative Example 1 are as follows: Figure 5 As shown.
[0082] Depend on Figure 1It can be seen that, compared to Comparative Example 1, oxidation preferentially occurs in Example 2, and the addition of additives reduces the oxidation potential of the electrolyte; Figure 2 and Figure 3 It can be seen that the charge / discharge specific capacity of Example 2 is better than that of Comparative Example 1, and the polarization is less than that of Comparative Example 1; Figure 4 It can be seen that the electrochemical impedance of Example 2 after 100 cycles is less than that of Comparative Example 1; compared with Table 1 and Figure 5 Analysis of the data shows that the lithium-ion pouch batteries formed with the high-voltage fast-charging electrolytes prepared in Examples 1-8 exhibit better capacity retention compared to Comparative Example 1. This significant improvement in capacity retention indicates that the batteries made with the electrolyte of this invention have a fundamentally improved electrode / electrolyte interface stability. This is attributed to the synergistic effect of main additive A and co-additive B on the surface of the high-voltage positive electrode, preferentially oxidizing and participating in the construction of a dense, uniformly composed solid electrolyte interface film. This film effectively inhibits the continuous decomposition of the electrolyte and the dissolution of transition metal ions, thereby significantly improving the battery's cycle life.
[0083] It is worth noting that this invention effectively improves the oxidation stability of the electrolyte system under high-voltage conditions by introducing a main additive with a specific structural formula and selected synergistic additives into the high-voltage electrolyte. The main additive, when the charging voltage rises to 4.5V and above, preferentially oxidizes on the positive electrode surface and participates in the formation of a dense and stable positive electrode electrolyte interface film, which effectively blocks direct contact between the electrolyte and the highly active positive electrode material, inhibiting the continuous decomposition of the electrolyte and the dissolution of transition metal ions. Simultaneously, the addition of synergistic additives further optimizes the composition, ion conductivity, and mechanical stability of the interface film, thereby significantly reducing the interfacial impedance and polarization degree of the battery during high-voltage cycling and improving the migration efficiency of lithium ions. Experimental results show that the lithium-ion battery using this electrolyte achieves a capacity retention rate of up to 97.08% after 100 cycles at a high voltage of 4.5V, exhibiting significantly better cycle stability than the control system without the main additive. Furthermore, by adjusting the structure of the R group in the main additive and its addition ratio in the electrolyte, the composition and properties of the interfacial film can be controlled, giving the electrolyte system good adaptability and designability, making it suitable for high-voltage lithium-ion batteries of different systems. This invention constructs a highly efficient multi-level electrode / electrolyte interface optimization system by introducing a main additive and synergistic additive with specific structures. Main additive A preferentially undergoes oxidative decomposition before the electrolyte solvent, forming a dense interfacial film on the positive electrode surface, blocking direct contact and continuous oxidation by the electrolyte; synergistic additive B further optimizes the composition and stability of the interfacial film through decomposition or reaction; the combined effect of the main additive and synergistic additive improves the battery's cycle performance under high voltage and effectively suppresses continuous side reactions under high voltage, resulting in higher capacity retention, lower polarization, and better interfacial stability during high-voltage long-cycle operation.
[0084] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
[0085] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.
Claims
1. A high-voltage electrolyte, characterized in that, It includes lithium salts, organic solvents, and functional additives; the functional additives include main additive A and synergistic additive B; The main additive A is a compound having the structure shown in formula (I): Equation (I); Wherein, R is selected from C1-C6 alkyl, alkoxy, alkenyl or alkynyl groups, wherein the alkyl, alkoxy, alkenyl or alkynyl groups may optionally be substituted.
2. The high-voltage electrolyte according to claim 1, characterized in that, The main additive A is selected from at least one of the following compounds: Equation 1-1; Equation 1-2; Equation 1-3.
3. A high-voltage electrolyte according to claim 1 or 2, characterized in that, Based on the total mass of the electrolyte, the content of the main additive A is 0.1wt% to 5wt%.
4. The high-voltage electrolyte according to claim 1, characterized in that, The synergistic additive B is selected from at least one of lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium difluorophosphate, and lithium bis(trifluoromethanesulfonyl)imide.
5. The high-voltage electrolyte according to claim 4, characterized in that, Based on the total mass of the electrolyte, the total content of the synergistic additive B is 0.1wt% to 5wt%.
6. The high-voltage electrolyte according to claim 1, characterized in that, The lithium salt comprises lithium hexafluorophosphate.
7. The high-voltage electrolyte according to claim 6, characterized in that, The concentration of lithium hexafluorophosphate in the electrolyte is 1.0 mol / L to 1.5 mol / L.
8. The high-voltage electrolyte according to claim 1, characterized in that, The organic solvent is selected from one or more combinations of ethylene carbonate, propylene carbonate, butene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, vinylene carbonate, and vinyl sulfite.
9. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a membrane disposed between the positive electrode and the negative electrode, and a high-voltage electrolyte as described in any one of claims 1-8.
10. A lithium-ion battery according to claim 9, characterized in that, The charging cutoff voltage of the lithium-ion battery is not lower than 4.5V.