Electrolyte, electrochemical device, and electronic device

Abstract

The invention provides an electrolyte, an electrochemical device and an electronic device, and belongs to the technical field of energy storage. Based on the mass of the electrolyte, the electrolyte comprises ethylene carbonate with the mass content of A%, methyl propyl carbonate with the mass content of B%, diethyl carbonate with the mass content of C%, ethyl propionate with the mass content of D% and propyl propionate with the mass content of E%; wherein 5 < = A < = 20, 10 < = B < = 20, and 0.1 < = A / (B + C + D + E) < = 0.5. By controlling the components and the mass content of the electrolyte, the components are matched with one another, so that the high-temperature cycle capacity retention ratio of the battery can be improved, the increase of the thickness of the battery in a high-temperature and high-humidity storage environment is controlled, the service life of the battery is prolonged, and the use safety of the battery is improved.

Description

Technical Field

[0001] This application belongs to the technical field of energy storage, and specifically relates to an electrolyte, an electrochemical device, and an electronic device. Background Art

[0002] As a rechargeable energy storage device, a secondary battery can store and release electrical energy through an electrochemical reaction, and is an indispensable key component for electronic devices, electric vehicles, and energy storage systems. With the continuous iterative upgrade of technology, lithium-ion batteries have been widely used due to their high energy density, long cycle life, and environmental friendliness.

[0003] However, when a lithium-ion battery is used on a rainy day in summer, it will face high temperature and high humidity conditions. At this time, the molecular movement of the electrolyte intensifies and the volume increases, resulting in an increase in the overall thickness of the battery, greatly reducing the service life of the battery. In addition, in the hot summer, during the long-term driving of an electric vehicle, the battery cell will heat up. Under high temperature conditions, the chemical reaction rate inside the battery accelerates, which may lead to an accelerated attenuation of the battery capacity, thereby reducing the safety of battery use. In order to improve the use effect of secondary batteries, it is necessary to improve the electrochemical performance of secondary batteries under high temperature and high humidity conditions. Summary of the Invention

[0004] In view of this, this application provides an electrolyte, an electrochemical device, and an electronic device. By regulating the components and mass contents of the electrolyte, the high-temperature cycle capacity retention rate of the electrochemical device can be improved, the increase in the thickness of the electrochemical device in a high-temperature and high-humidity storage environment can be controlled, the service life of the electrochemical device can be extended, and the use safety of the electrochemical device can be improved.

[0005] In a first aspect, this application provides an electrolyte. Based on the mass of the electrolyte, the electrolyte includes: ethylene carbonate with a mass content of A%, methyl propyl carbonate with a mass content of B%, diethyl carbonate with a mass content of C%, ethyl propionate with a mass content of D%, and propyl propionate with a mass content of E%; wherein, 5 ≤ A ≤ 20, 10 ≤ B ≤ 20, and 0.1 ≤ A / (B + C + D + E) ≤ 0.5. By controlling the components and mass contents of the electrolyte, this application can improve the high-temperature cycle capacity retention rate of the electrochemical device, control the increase in the thickness of the electrochemical device in a high-temperature and high-humidity storage environment, extend the service life of the electrochemical device, and improve the use safety of the electrochemical device.

[0006] In some embodiments, the electrolyte satisfies at least one of the following conditions:

[0007] (1) 7 ≤ A ≤ 12;

[0008] (2) 13 ≤ B ≤ 17;

[0009] (3) 5 ≤ C ≤ 20;

[0010] (4) 20 ≤ D ≤ 40;

[0011] (5) 5 ≤ E ≤ 20;

[0012] (6) 0.15 ≤ A / (B + C + D + E) ≤ 0.3. When the mass contents of the components of the electrolyte satisfy the above ranges, it can promote better cooperation of the components, further improve the high-temperature cycle capacity retention rate of the electrochemical device, and control the increase in the thickness of the electrochemical device in a high-temperature and high-humidity storage environment.

[0013] In some embodiments, based on the mass of the electrolyte, the electrolyte includes: adiponitrile with a mass content of F%, succinonitrile with a mass content of G%, 1,3,6-hexanetricarbonitrile with a mass content of H%; 1 ≤ F ≤ 3, 2 ≤ H ≤ 4, and 1 ≤ (F + G) / H ≤ 1.5. Adding a certain mass of adiponitrile, succinonitrile, and 1,3,6-hexanetricarbonitrile to the electrolyte of the present application can further improve the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0014] In some embodiments, the electrolyte includes a first component, and the first component includes 1H-imidazole-4-carbonitrile and / or 1,2-dimethyl-1H-imidazole-4,5-dicarbonitrile; based on the mass of the electrolyte, the mass content of the first component is Y%; 0.5 ≤ Y ≤ 1; and / or, 0.125 ≤ Y / H ≤ 0.5. Adding the first component to the electrolyte system of the present application and controlling the mass content of the first component can adsorb with active metal sites, reduce the oxidative decomposition of the electrolyte by the positive electrode, and reduce the moisture in the electrolyte, thereby further improving the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0015] In some embodiments, the electrolyte includes fluoroethylene carbonate; based on the mass of the electrolyte, the mass content of fluoroethylene carbonate is P%, 1 ≤ P ≤ 15; preferably, 4 ≤ P ≤ 8. Adding fluoroethylene carbonate (FEC) to the electrolyte system of the present application, by controlling the mass content to satisfy the above ranges, can protect the negative electrode, reduce the reduction decomposition gas production of the solvent in the electrolyte on the negative electrode side, and at the same time avoid the damage of the decomposition by-products of FEC to the positive electrode, reduce the violent gas production caused by the damage to the positive electrode structure, thereby further improving the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0016] In some embodiments, the electrolyte includes 1,3 - propane sultone; based on the mass of the electrolyte, the mass content of 1,3 - propane sultone is Q%, and 2 ≤ Q ≤ 4. Adding 1,3 - propane sultone to the electrolyte of the present application can participate in film formation at the positive and negative electrodes, further improving the high - temperature cycling performance and high - temperature and high - humidity storage performance of the electrochemical device. By controlling its mass content, the battery polarization caused by side reactions of the electrolyte can be reduced, and the kinetics and high - temperature cycling performance of the electrochemical device can be balanced.

[0017] In some embodiments, the electrolyte includes lithium hexafluorophosphate and a second lithium salt, and the second lithium salt includes lithium bis(oxalato)borate and / or lithium tetraborate; based on the mass of the electrolyte, the mass content of the second lithium salt is U%, and 0.3 ≤ U ≤ 0.8. The present application uses the second lithium salt to absorb HF generated by the decomposition of lithium hexafluorophosphate and the electrolyte, and can also form a film on the positive electrode, reducing the oxidative decomposition of the electrolyte by the positive electrode, thereby further improving the high - temperature cycling performance and high - temperature and high - humidity storage performance of the electrochemical device.

[0018] In some embodiments, the electrolyte includes a second component, and the second component includes at least one of 1,2,4 - triethylcyclohexane, 1,2,4 - trimethylcyclohexane, or 1,4 - dimethylcyclohexane; based on the mass of the electrolyte, the mass content of the second component is X%, and 0.5 ≤ X ≤ 0.8. Adding the second component to the electrolyte system of the present application can participate in film formation at the positive and negative electrodes of the electrochemical device respectively. Film formation at the negative electrode can inhibit side reactions, and film formation at the positive electrode is beneficial to reducing the oxidative decomposition of the electrolyte by the positive electrode, thereby further improving the high - temperature cycling performance and high - temperature and high - humidity storage performance of the electrochemical device.

[0019] In some embodiments, the electrolyte includes a third component, and the third component includes at least one of 3,6 - bis(2 - pyridyl)-1,2,4,5 - tetrazine, 3,6 - bis(4 - pyridyl)-1,2,4,5 - tetrazine, or 2,4,6 - tris(4 - pyridyl)-1,3,5 - triazine; based on the mass of the electrolyte, the mass content of the third component is Z%, and 0.3 ≤ Z ≤ 0.8. Adding the third component to the electrolyte helps the electrolyte to form a film at the positive - electrode interface, further reducing the oxidative decomposition of the electrolyte by the positive electrode, thereby being beneficial to further improving the high - temperature cycling performance and high - temperature and high - humidity storage performance of the electrochemical device.

[0020] In the second aspect of the present application, an electrochemical device is provided, including a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is selected from any one of the above - mentioned electrolytes.

[0021] In the third aspect of the present application, an electronic device is provided, including any one of the above - mentioned electrochemical devices.

[0022] Advantages of the present application:

[0023] The present application provides an electrolyte, an electrochemical device, and an electronic device. Based on the mass of the electrolyte, the electrolyte includes: ethylene carbonate with a mass content of A%, methyl propyl carbonate with a mass content of B%, diethyl carbonate with a mass content of C%, ethyl propionate with a mass content of D%, and propyl propionate with a mass content of E%; wherein, 5 ≤ A ≤ 20, 10 ≤ B ≤ 20, and 0.5 ≤ A / (B + C + D + E) ≤ 8. By regulating the components and mass contents of the electrolyte, the high-temperature cycle capacity retention rate of the electrochemical device can be improved, and the increase in the thickness of the electrochemical device in a high-temperature and high-humidity storage environment can be reduced; in particular, by further optimizing the formulation of the additive in combination with this electrolyte system, the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device can be further improved, thereby extending the service life of the electrochemical device and enhancing the use safety of the electrochemical device. Detailed implementation manners

[0024] In order to make the objectives, technical solutions, and advantages of the present application clearer, the following further describes the present application in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] To solve the problems of the prior art, a first aspect of the present application provides an electrolyte. Based on the mass of the electrolyte, the electrolyte includes: ethylene carbonate with a mass content of A%, methyl propyl carbonate with a mass content of B%, diethyl carbonate with a mass content of C%, ethyl propionate with a mass content of D%, and propyl propionate with a mass content of E%; wherein, 5 ≤ A ≤ 20, 10 ≤ B ≤ 20, and 0.1 ≤ A / (B + C + D + E) ≤ 0.5. By controlling the components and mass contents of the electrolyte, the present application enables ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate to cooperate with each other, and the mass contents of ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate are within the scope of the present application. Ethylene carbonate effectively solvates lithium ions, fully dissociates lithium salts to reduce polarization, and is combined with the use of methyl propyl carbonate and diethyl carbonate. In particular, regulating methyl propyl carbonate to meet the above mass content range and mixing it with ethylene carbonate can reduce the overall viscosity of the electrolyte and improve the conduction efficiency of lithium ions, and also helps to reduce the volatilization of the electrolyte. However, both methyl propyl carbonate and diethyl carbonate are prone to side reaction decomposition at high temperatures, increasing the viscosity of the electrolyte and reducing the ionic conductivity. The present application combines the use of ethyl propionate and propyl propionate, which can further reduce the viscosity of the electrolyte and help to improve the wettability of the electrolyte. When the mass contents of ethylene carbonate and the above other components meet the above relationship, it can improve the contact effect between the electrolyte and the positive and negative electrode active materials and form a high-density interfacial film, strengthen the protection on the positive electrode interface and optimize the SEI film on the negative electrode, thereby reducing the side reactions at the interface under high-temperature environments and improving the stability of the electrolyte. The solvation effect of ethylene carbonate can also keep the electrolyte with a relatively high ionic conductivity under high-temperature conditions; in addition, the inventors also found that: the above electrolyte system can also reduce the water absorption of the electrolyte under high-temperature and high-humidity conditions, and the dense interfacial film is also beneficial to preventing the penetration of water and the decomposition of the electrolyte, thereby being able to improve the high-temperature cycle capacity retention rate of the battery, control the increase in the thickness of the battery under high-temperature and high-humidity storage environments, extend the service life of the battery, and enhance the safety of battery use.

[0026] In some embodiments, 5 ≤ A ≤ 20, preferably 7 ≤ A ≤ 12. For example, A can be 5, 6, 8, 9, 10, 12, 14, 16, 17, 19, 20, or values within the range composed of any two of these values. Regulating the mass content of ethylene carbonate to meet the above range is beneficial for cooperating with other components of the electrolyte, forming a high-density interfacial film on the positive and negative electrodes, reducing the side reactions at the interface under high-temperature environments, and fully dissociating lithium salts to reduce polarization, thereby improving the high-temperature cycle capacity retention rate of the battery and controlling the increase in the thickness of the battery under high-temperature and high-humidity storage environments.

[0027] In some embodiments, 10 ≤ B ≤ 20, preferably 13 ≤ B ≤ 17. For example, B can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or a value within the range formed by any two of these values. Controlling the mass content of methyl propyl carbonate to meet the above range is beneficial for cooperation with other components of the electrolyte, and further improves the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0028] In some embodiments, 5 ≤ C ≤ 20, preferably 8 ≤ C ≤ 14. For example, C can be 5, 6, 8, 9, 10, 12, 14, 16, 17, 19, 20, or a value within the range formed by any two of these values. Controlling the mass content of diethyl carbonate to meet the above range is beneficial for cooperation with other components of the electrolyte, and further improves the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0029] In some embodiments, 20 ≤ D ≤ 40, preferably 24 ≤ D ≤ 35. For example, D can be 20, 23, 24, 25, 26, 29, 31, 34, 35, 36, 38, 39, 40, or a value within the range formed by any two of these values. Controlling the mass content of ethyl propionate to meet the above range is beneficial for cooperation with other components of the electrolyte, and further improves the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0030] In some embodiments, 5 ≤ E ≤ 20, preferably 8 ≤ E ≤ 14. For example, E can be 5, 6, 8, 9, 10, 12, 14, 16, 17, 19, 20, or a value within the range formed by any two of these values. Controlling the mass content of propyl propionate to meet the above range is beneficial for cooperation with other components of the electrolyte, and further improves the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0031] In some embodiments, 0.1 ≤ A / (B + C + D + E) ≤ 0.5, preferably 0.15 ≤ A / (B + C + D + E) ≤ 0.3. For example, the value of A / (B + C + D + E) can be 0.1, 0.12, 0.16, 0.19, 0.25, 0.31, 0.34, 0.41, 0.42, 0.46, 0.5, or a value within the range formed by any two of these values. In this application, controlling the mass content ratio of ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate to conform to the above relationship can enable the electrolyte to better play the role of mutual cooperation, thereby further improving the high-temperature cycling capacity retention rate of the battery, controlling the increase in the battery thickness in a high-temperature and high-humidity storage environment, extending the battery life, and enhancing the battery usage safety.

[0032] In some embodiments, based on the mass of the electrolyte, the electrolyte comprises: adiponitrile with a mass content of F%, succinonitrile with a mass content of G%, and 1,3,6-hexanetricarbonitrile with a mass content of H%; 1 ≤ F ≤ 3, 2 ≤ H ≤ 4, and 1 ≤ (F + G) / H ≤ 1.5. For example, the value of (F + G) / H can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, or a value within the range formed by any two of these values. By regulating the mass content ratio of adiponitrile, succinonitrile, and 1,3,6-hexanetricarbonitrile to meet the above relationship, the electrolyte can better play a cooperative role, thereby further improving the high-temperature cycle capacity retention rate of the battery, enhancing the hydrophobicity of the electrolyte, reducing the water absorption of the electrolyte, and being able to complex with positive metal ions to form a stable protective film on the positive electrode surface, reducing the occurrence of gas-generation side reactions, improving the gas-generation problem, thereby improving the increase in battery thickness in a high-temperature and high-humidity storage environment, extending the battery life, and enhancing the battery usage safety.

[0033] In the above embodiments, 1 ≤ F ≤ 3. For example, F can be 1, 1.2, 1.3, 1.5, 1.7, 1.9, 2.2, 2.5, 2.7, 2.8, 3, or a value within the range formed by any two of these values. Regulating the mass content of adiponitrile to meet the above range is beneficial for cooperation with other components of the electrolyte, and further improves the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0034] In the above embodiments, 2 ≤ H ≤ 4. For example, H can be 2, 2.1, 2.3, 2.5, 2.8, 3.1, 3.2, 3.5, 3.6, 3.9, 4, or a value within the range formed by any two of these values. Regulating the mass content of 1,3,6-hexanetricarbonitrile to meet the above range is beneficial for cooperation with other components of the electrolyte, and further improves the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0035] In some embodiments, the electrolyte comprises a first component, and the first component comprises 1H-imidazole-4-carbonitrile and / or 1,2-dimethyl-1H-imidazole-4,5-dicarbonitrile; based on the mass of the electrolyte, the mass content of the first component is Y%; 0.5 ≤ Y ≤ 1; and / or, 0.125 ≤ Y / H ≤ 0.5. Adding the first component to the electrolyte system of the present application and controlling the mass content of the first component can utilize the cyanide groups contained in its molecules to adsorb on active metal sites, reduce the oxidation of the electrolyte by the positive electrode, and the imidazole group can absorb trace water molecules entering the electrolyte to prevent the generation of HF from damaging the positive electrode structure, thereby complexing with transition metal sites through the positive electrode interface, reducing the oxidative decomposition of the electrolyte by the positive electrode, and further improving the high-temperature cycle performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0036] In the above embodiments, 0.5 ≤ Y ≤ 1. For example, Y can be 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a value within the range formed by any two of these values. By adjusting the mass content of the first component to meet the above range in this application, it is beneficial to cooperate with other components of the electrolyte, and further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0037] In the above embodiments, 0.125 ≤ Y / H ≤ 0.5. For example, the value of Y / H can be 0.125, 0.16, 0.21, 0.23, 0.29, 0.31, 0.37, 0.41, 0.42, 0.49, 0.5 or a value within the range formed by any two of these values. By adjusting the mass content ratio of the first component to 1,3,6-hexanetricarbonitrile to meet the above relationship in this application, the electrolyte can better play the role of mutual cooperation, thereby further improving the high-temperature cycling capacity retention rate of the battery, controlling the increase in the thickness of the battery in a high-temperature and high-humidity storage environment, prolonging the service life of the battery, and enhancing the safety of battery use.

[0038] In some embodiments, the electrolyte includes fluoroethylene carbonate. Adding fluoroethylene carbonate to the electrolyte system of this application can control the gas generated during the operation of the electrolyte. Based on the mass of the electrolyte, the mass content of fluoroethylene carbonate is P%, 1 ≤ P ≤ 15, preferably 4 ≤ P ≤ 8. For example, P can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or a value within the range formed by any two of these values. By controlling the mass content of fluoroethylene carbonate (FEC) to meet the above range in this application, on the one hand, it can reduce the side reaction of FEC defluorinating and dehydrogenating during operation, and reduce the damage to the positive electrode structure caused by the generated HF; on the other hand, it can also reduce the reduction decomposition of the electrolyte on the negative electrode side and reduce the damage to the negative electrode structure caused by the generated gas. Therefore, controlling the mass content of fluoroethylene carbonate within the above range can play a role in protecting the positive and negative electrodes of the battery, and further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0039] In some embodiments, the electrolyte includes 1,3 - propane sultone. Adding 1,3 - propane sultone to the electrolyte of the present application can improve the working efficiency of the battery cell. Based on the mass of the electrolyte, the mass content of 1,3 - propane sultone is Q%, where 2 ≤ Q ≤ 4. For example, Q can be 2, 2.1, 2.3, 2.5, 2.8, 3.1, 3.2, 3.5, 3.6, 3.9, 4, or a value within the range formed by any two of these values. By regulating the mass content of 1,3 - propane sultone in the electrolyte to meet the above range, it can participate in film formation at the positive and negative electrodes, reduce the gas generation amplitude under high - temperature and high - humidity storage conditions, and also reduce the side reactions of the electrolyte and the polarization of the battery, thereby improving the high - temperature cycling performance of the electrochemical device.

[0040] In some embodiments, the electrolyte includes lithium hexafluorophosphate and a second lithium salt, and the second lithium salt includes lithium bis(oxalato)borate and / or lithium tetraborate. Based on the mass of the electrolyte, the mass content of the second lithium salt is U%, where 0.3 ≤ U ≤ 0.8. For example, U can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or a value within the range formed by any two of these values. By regulating the mass content of the second lithium salt in the present application to meet the above range, it can cooperate with other components of the electrolyte. By combining the electron - deficient boron atom in the second lithium salt with the electron - rich fluorine atom in HF, it can absorb HF generated by the decomposition of lithium hexafluorophosphate and other components of the electrolyte, and can also form a dense boron - containing CEI film on the positive electrode at high voltage, reducing the oxidative decomposition of the positive electrode to the electrolyte, thereby further improving the high - temperature cycling performance and high - temperature and high - humidity storage performance of the electrochemical device.

[0041] In some embodiments, the electrolyte includes a second component, and the second component includes at least one of 1,2,4 - triethylcyclohexane, 1,2,4 - trimethylcyclohexane, or 1,4 - dimethylcyclohexane. Based on the mass of the electrolyte, the mass content of the second component is X%, where 0.5 ≤ X ≤ 0.8. For example, X can be 0.5, 0.6, 0.7, 0.8, or a value within the range formed by any two of these values. By regulating the mass content of the second component in the present application to meet the above range and cooperating with other components of the electrolyte, it helps the electrolyte to form a film on the positive and negative electrodes of the battery, inhibits side reactions at the positive and negative electrode interfaces, and reduces the oxidative decomposition of the electrolyte. Moreover, by using the relatively high oxidation window of cyclohexane - based additives, the overall oxidation window of the electrolyte can be increased in a high - temperature environment, improving the residual capacity after high - temperature cycling and the increase in battery thickness, thereby further improving the high - temperature cycling performance and high - temperature and high - humidity storage performance of the electrochemical device.

[0042] In some embodiments, the electrolyte includes a third component, and the third component includes at least one of 3,6-di-2-pyridyl-1,2,4,5-tetrazine, 3,6-di-4-pyridyl-1,2,4,5-tetrazine, or 2,4,6-tris(4-pyridyl)-1,3,5-triazine. Based on the mass of the electrolyte, the mass content of the third component is Z%, where 0.3 ≤ Z ≤ 0.8. For example, Z can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or a value within the range formed by any two of these values. In this application, the mass content of the third component is regulated to meet the above range and cooperate with other components of the electrolyte. By using the nitrogen atoms of such azine additives to bind to the transition metal atoms on the surface of the positive electrode, the quality of the film formation at the positive electrode interface is improved, the oxidative decomposition of the electrolyte by the positive electrode is further reduced, the oxygen release at high temperatures and its damage to the positive electrode structure are inhibited, and an SEI film rich in Li3N substances can be formed at the negative electrode interface, strengthening the quality of the SEI, which is beneficial to further improving the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0043] In this application, the electrolyte may further include other organic solvents. There is no particular limitation on the types of other organic solvents in this application, as long as the objectives of this application can be achieved. For example, it may include but is not limited to at least one of ether compounds, dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, or other organic solvents. The above ether compounds may include but are not limited to at least one of ethylene glycol dimethyl ether, dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran.

[0044] In the second aspect of this application, an electrochemical device is provided, which includes a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is selected from any of the above electrolytes. There is no particular limitation on the electrochemical device of this application, and it may include any device that undergoes an electrochemical reaction, such as a secondary battery. There is no particular limitation on the secondary battery of this application. For example, it may include but is not limited to: a lithium-ion secondary battery (also known as a lithium-ion battery) or a sodium-ion secondary battery.

[0045] In this application, the negative electrode includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; the "negative electrode active material layer located on at least one surface of the negative electrode current collector" means that the negative electrode active material layer can be located on one surface of the negative electrode current collector along its own thickness direction, or can be located on both surfaces of the negative electrode current collector along its own thickness direction. It should be noted that the "surface" here can be the entire area of the surface of the negative electrode current collector, or a partial area of the surface of the negative electrode current collector. There is no special limitation in this application, as long as the purpose of this application can be achieved.

[0046] This application does not particularly limit the negative electrode current collector, as long as the purpose of this application can be achieved. For example, it can include, but is not limited to, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collectors (such as carbon-copper composite current collectors, nickel-copper composite current collectors, titanium-copper composite current collectors, etc.). In this application, there is no special limitation on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of this application can be achieved.

[0047] The negative electrode active material layer in this application may further include a negative electrode binder and a negative electrode conductive agent, or the negative electrode active material layer may further include a negative electrode binder, a negative electrode conductive agent, and a thickening agent. This application does not particularly limit the type of the negative electrode binder in the negative electrode active material layer, as long as the purpose of this application can be achieved. For example, the negative electrode binder can include, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, modified polyvinylidene fluoride, modified styrene-butadiene rubber (SBR), or polyurethane. In some embodiments, the polyolefin binder includes at least one of polyethylene, polypropylene, polyacrylate, polyvinyl alcohol, or polyacrylic acid. This application does not particularly limit the type of the negative electrode conductive agent in the negative electrode active material layer, as long as the purpose of this application can be achieved. In some embodiments, the negative electrode conductive agent includes carbon-based materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, or carbon fiber; metal-based materials, such as metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof. This application does not particularly limit the type of the thickening agent, as long as the purpose of this application can be achieved. For example, the thickening agent can include, but is not limited to, at least one of sodium carboxymethyl cellulose or carboxymethyl cellulose. This application does not particularly limit the mass ratio of the negative electrode active material, the negative electrode conductive agent, the negative electrode binder, and the thickening agent in the negative electrode active material layer. Those skilled in the art can select according to actual needs, as long as the purpose of this application can be achieved.

[0048] In the present application, the positive electrode includes a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector. The above-mentioned "positive electrode active material layer located on at least one surface of the positive electrode current collector" means that the positive electrode active material layer can be located on one surface of the positive electrode current collector along its own thickness direction, or can be located on both surfaces of the positive electrode current collector along its own thickness direction. It should be noted that the "surface" here can be the entire area of the surface of the positive electrode current collector, or can be a partial area of the surface of the positive electrode current collector. There is no special limitation in the present application, as long as the purpose of the present application can be achieved.

[0049] There is no special limitation on the positive electrode current collector in the present application, as long as the purpose of the present application can be achieved. For example, the positive electrode current collector can include aluminum foil, aluminum alloy foil or composite current collector (such as aluminum-carbon composite current collector), etc. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate.

[0050] The positive electrode active material layer of the present application includes a positive electrode active material. There is no special limitation on the type of the positive electrode active material in the present application, as long as the purpose of the present application can be achieved. For example, the positive electrode active material can include at least one of lithium nickel cobalt manganese oxide (LiNi 0.90 Co 0.05 Mn 0.05 O2 (NCM955), NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide (LiCoO2), lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel-type manganese oxide, spinel-type nickel manganese oxide and lithium titanate. In the present application, the positive electrode active material can also include non-metallic elements. For example, the non-metallic elements include at least one of fluorine, phosphorus, boron, chlorine, silicon or sulfur. In the present application, there is no special limitation on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, and the thickness of the single-sided positive electrode active material layer is 30 μm to 120 μm.

[0051] In the present application, the positive electrode active material layer can also include a positive electrode binder and a positive electrode conductive agent. There is no special limitation on the type of the positive electrode binder in the positive electrode active material layer in the present application, as long as the purpose of the present application can be achieved. For example, the positive electrode binder can include, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, modified polyvinylidene fluoride, modified styrene-butadiene rubber (SBR) or polyurethane. In some embodiments, the polyolefin binder includes at least one of polyethylene, polypropylene, polyacrylate, polyvinyl alcohol or polyacrylic acid.

[0052] There is no particular limitation on the type of the positive electrode conductive agent in the positive electrode active material layer of the present application, as long as the object of the present application can be achieved. In some embodiments, the positive electrode conductive agent includes carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black or carbon fiber; metal-based materials such as metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof. There is no particular limitation on the mass ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder in the positive electrode active material layer of the present application, and those skilled in the art can select according to actual needs as long as the object of the present application can be achieved. For example, the loading amount of the positive electrode active material in the positive electrode sheet is 4.0 mg / cm 2 to 10.0 mg / cm 2 .

[0053] In order to prevent short circuit, a separator is usually provided between the positive electrode and the negative electrode of the secondary battery. In this case, the electrolyte of the present application usually penetrates into the separator and is used.

[0054] There is no particular limitation on the material and shape of the separator, as long as the effects of the present application are not impaired. The separator can be a resin, glass fiber, inorganic substance, etc. formed of a material that is stable to the electrolyte of the present application. In some embodiments, the separator includes a porous sheet or a non-woven fabric-like substance with excellent liquid retention properties. Examples of the material of the resin or glass fiber separator may include, but are not limited to, polyolefin, aromatic polyamide, polytetrafluoroethylene, polyethersulfone, etc. In some embodiments, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The above-mentioned materials of the separator can be used alone or in any combination.

[0055] The separator can also be a material formed by laminating the above-mentioned materials, and examples thereof include, but are not limited to, a three-layer separator laminated in the order of polypropylene, polyethylene, and polypropylene.

[0056] Examples of the material of the inorganic substance may include, but are not limited to, oxides such as alumina and silica, nitrides such as aluminum nitride and silicon nitride, and sulfates (such as barium sulfate and calcium sulfate). The form of the inorganic substance may include, but is not limited to, granular or fibrous.

[0057] The morphology of the separator can be in the form of a thin film, and its examples include, but are not limited to, non-woven fabric, woven fabric, microporous membrane, etc. In the form of a thin film, the pore size of the separator is from 0.01 μm to 1 μm, and the thickness is from 5 μm to 50 μm. In addition to the above-mentioned independent thin-film separators, the following separators can also be used: a separator formed by forming a composite porous layer containing the above-mentioned inorganic particles on the surface of the positive electrode and / or negative electrode by using a resin-based binder. For example, a separator formed by using a fluororesin as a binder to form a porous layer on both sides of the positive electrode with 90% of the alumina particles having a particle size less than 1 μm.

[0058] The thickness of the separator is arbitrary. In some embodiments, the thickness of the separator is greater than 1 μm, greater than 5 μm or greater than 8 μm. In some embodiments, the thickness of the separator is less than 50 μm, less than 40 μm or less than 30 μm. When the thickness of the separator is within the above range, insulation and mechanical strength can be ensured, and the rate performance and energy density of the secondary battery can be ensured.

[0059] The secondary battery of the present application further includes a packaging bag for accommodating the positive electrode, negative electrode, separator and electrolyte, as well as other components known in the art in the secondary battery. The present application does not limit the above-mentioned other components. The present application has no particular limitation on the packaging bag, and it can be a packaging bag well-known in the art as long as it can achieve the purpose of the present application.

[0060] The preparation process of the secondary battery of the present application is well-known to those skilled in the art, and the present application has no particular limitation. For example, it may include, but is not limited to, the following steps: stacking the positive electrode sheet, separator and negative electrode sheet in sequence, and performing operations such as winding and folding as needed to obtain a wound electrode assembly, putting the electrode assembly into a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain a secondary battery; or stacking the positive electrode sheet, separator and negative electrode sheet in sequence, and then fixing the four corners of the entire laminated structure with tape to obtain a laminated electrode assembly, putting the electrode assembly into a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain a secondary battery. In addition, an overcurrent protection element, a guide plate, etc. can also be placed in the packaging bag as needed to prevent the pressure inside the secondary battery from rising and overcharging and overdischarging.

[0061] The third aspect of the present application provides an electronic device including the above-mentioned electrochemical device.

[0062] The use of the electrochemical device of the present application is not particularly limited, and it can be used in any electronic device known in the prior art. In some embodiments, the electronic devices of the present application include, but are not limited to, laptop computers, pen input computers, mobile computers, e-book players, mobile phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, liquid crystal televisions, portable cleaners, portable CD players, mini discs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0063] Examples

[0064] The solution of the present application will be described below by taking a lithium-ion battery as an example in combination with the following specific examples. Unless otherwise specified, the raw materials used in the following examples are all from ordinary commercially available products, and the devices or equipment used are all purchased from conventional market sales channels. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0065] Test methods

[0066] High-temperature cycle capacity retention rate test:

[0067] Test temperature: 45 °C;

[0068] 1. Adjust the oven temperature to 45 °C, and let the battery stand in the oven for 60 min;

[0069] 2. According to the battery capacity, perform charge and discharge tests under the following conditions:

[0070] Constant current charge at 1C to 4.3V, then constant voltage charge (CV) until the current is 0.5C; subsequently, constant current charge at 0.5C to 4.5V, and then perform constant voltage charge (CV) until the current is less than 0.05C; stand for 5 min; discharge at 0.5C constant current to 3V. Record the discharge capacity of the first cycle.

[0071] 3. Cycle 600 times according to the above charge and discharge test conditions, and record the discharge capacity of the 600th cycle.

[0072] High-temperature cycle capacity retention rate (%) = (discharge capacity of the 600th cycle / discharge capacity of the first cycle) × 100%.

[0073] High-temperature and high-humidity storage gas generation performance test:

[0074] 1. Adjust the oven temperature to room temperature (25 °C), and let the battery stand at this temperature for 60 min;

[0075] 2. Charge the battery at a constant current of 0.2C to 4.5V according to the specific capacity of the battery, and then charge it at a constant voltage of 4.5V until the current is less than 0.05C. Record the battery thickness at room temperature.

[0076] 3. Transfer the battery to an oven at 80°C with a humidity of 90% and store it for 24h. Immediately measure the thickness of the battery after storage after the storage time ends.

[0077] Growth rate of thickness after high-temperature and high-humidity storage (%) = (Battery thickness after storage - Battery thickness at room temperature) / Battery thickness at room temperature × 100%.

[0078] Example 1-1

[0079] <Preparation of electrolyte>

[0080] In a dry argon atmosphere glove box, mix ethylene carbonate (A%), methyl propyl carbonate (B%), diethyl carbonate (C%), ethyl propionate (D%), propyl propionate (E%) and propyl butyrate as the base solvent. Dissolve lithium hexafluorophosphate (LiPF6) as the supporting electrolyte and the additive fluoroethylene carbonate in the above base solvent to obtain the electrolyte. Based on the mass of the electrolyte, the mass content of lithium hexafluorophosphate is 13.5%, and the mass contents of ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, propyl propionate and fluoroethylene carbonate are shown in Table 1 below, and the balance is propyl butyrate.

[0081] <Separator>

[0082] Use a polyethylene-polypropylene composite film with a thickness of 7μm.

[0083] <Preparation of positive electrode sheet>

[0084] Mix the positive electrode active material lithium cobaltate (LiCoO2), the positive electrode binder polyvinylidene fluoride (PVDF), and the positive electrode conductive agent Super P according to a mass ratio of 96:2.2:1.8, add N-methylpyrrolidone (NMP) as a solvent, and prepare a slurry with a solid content of 75wt% and stir evenly. Coat the positive electrode slurry evenly on a positive electrode current collector aluminum foil with a thickness of 10μm, dry, cold press, cut, and then weld the tab to obtain the positive electrode sheet.

[0085] <Preparation of negative electrode sheet>

[0086] Mix silicon carbide particles and graphite particles in a mass ratio of 2:3 to obtain the negative electrode active material; mix the negative electrode active material, the negative electrode conductive agent Super P, the thickening agent sodium carboxymethyl cellulose (CMC), and the negative electrode binder polymethyl acrylate (PMA) in a mass ratio of 96:1.5:1:1.5, and then add deionized water as a solvent to formulate a negative electrode slurry with a solid content of 60 wt%. Coating the negative electrode slurry evenly on a negative electrode current collector copper foil with a thickness of 10 μm, drying, cold pressing, cutting, and then welding the tab to obtain the negative electrode plate.

[0087] <Preparation of Lithium-Ion Battery>

[0088] Stack the above positive electrode plate, separator, and negative electrode plate in sequence, with the separator placed in the middle of the positive electrode plate and the negative electrode plate to play a blocking role, and then wind to obtain the electrode assembly. Place the electrode assembly in an aluminum-plastic film packaging shell, dry it in a vacuum oven at 85 °C for 12 hours to remove moisture, inject the prepared electrolyte, and obtain the lithium-ion battery through processes such as vacuum packaging, standing, and formation.

[0089] Compared with Example 1-1, the main difference in each example and comparative example in Table 1 is that the parameters are adjusted as shown in Table 1. The performance test results of the lithium-ion batteries in each example and comparative example are shown in Table 1.

[0090] Table 1

[0091]

[0092] As can be seen from Table 1, in this application, by controlling the mass content compliance relationship of ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate: 5 ≤ A ≤ 20, 10 ≤ B ≤ 20, and 0.1 ≤ A / (B + C + D + E) ≤ 0.5, the capacity retention rate of the secondary battery under high-temperature cycling conditions can be improved, and the increase in battery thickness under high-temperature and high-humidity storage conditions can be reduced, improving the high-temperature cycling performance and high-temperature and high-humidity storage performance. In particular, when the electrolyte satisfies at least one of the following conditions: (1) 7 ≤ A ≤ 12, (2) 13 ≤ B ≤ 17, (3) 5 ≤ C ≤ 20, (4) 20 ≤ D ≤ 40, (5) 5 ≤ E ≤ 20, (6) 0.15 ≤ A / (B + C + D + E) ≤ 0.3, it is beneficial to further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the secondary battery.

[0093] Specifically, adding fluoroethylene carbonate to the electrolyte and controlling its mass content P% to satisfy 1 ≤ P ≤ 15 can cooperate with the above electrolyte system to improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the secondary battery; in particular, when 4 ≤ P ≤ 8, it can further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the secondary battery.

[0094] Compared with Example 1-1, the main difference in each example in Table 2 is that the electrolyte is prepared by a method including the following steps:

[0095] In a dry argon atmosphere glove box, adiponitrile (F%), succinonitrile (G%), 1,3,6-hexanetricarbonitrile (H%), the first component (Y%), and 1,3-propane sultone (Q%) are dissolved in a solution containing ethylene fluorocarbonate, propyl butyrate, ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate. Based on the mass of the electrolyte, the mass contents of ethylene fluorocarbonate, ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate are the same as those in Example 1-1, and the mass contents of adiponitrile, succinonitrile, 1,3,6-hexanetricarbonitrile, the first component, and 1,3-propane sultone are shown in Table 2, with the balance being propyl butyrate.

[0096] Table 2

[0097]

[0098]

[0099] As can be seen from Table 2, adding adiponitrile, succinonitrile, and 1,3,6-hexanetricarbonitrile to the above electrolyte system and controlling their mass ratios to satisfy 1 ≤ F ≤ 3, 2 ≤ H ≤ 4, and 1 ≤ (F + G) / H ≤ 1.5 can further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0100] In particular, when the first component is added to cooperate with the above electrolyte system in this application and the mass content Y% of the first component is controlled to satisfy 0.5 ≤ Y ≤ 1 and / or 0.125 ≤ Y / H ≤ 0.5, the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device can be further improved. In particular, when 0.18 ≤ Y / H ≤ 0.36 is satisfied, the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device can be further improved.

[0101] In particular, when 1,3-propane sultone is included in the electrolyte and the mass content Q% satisfies 2 ≤ Q ≤ 4, the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device can be further improved.

[0102] Compared with Example 2-10, the main difference in each example in Table 3 is that the electrolyte is prepared by a method including the following steps:

[0103] In a dry argon atmosphere glove box, dissolve the second lithium salt (U%), adiponitrile (F%), succinonitrile (G%), 1,3,6-hexanetricarbonitrile (H%), the first component (Y%), 1,3-propane sultone (Q%), the second component (X%), and the third component (Z%) in a solution containing fluoroethylene carbonate, propyl butyrate, ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate. Based on the mass of the electrolyte, the mass contents of fluoroethylene carbonate, ethylene carbonate, methyl propyl carbonate, diethyl carbonate, ethyl propionate, and propyl propionate are the same as those in Examples 2-10. The mass contents of adiponitrile, succinonitrile, 1,3,6-hexanetricarbonitrile, the first component, and 1,3-propane sultone are shown in Table 3, and the balance is propyl butyrate.

[0104] Table 3

[0105]

[0106] As can be seen from Table 3, adding the second lithium salt to the above electrolyte and controlling the mass content U% to satisfy 0.3 ≤ U ≤ 0.8 can further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device. In particular, when the electrolyte further includes the second component with a mass content X% satisfying 0.5 ≤ X ≤ 0.8, the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device can be further improved. More preferably, adding the third component to the above electrolyte and controlling the mass content Z% to satisfy 0.3 ≤ Z ≤ 0.8 can further improve the high-temperature cycling performance and high-temperature and high-humidity storage performance of the electrochemical device.

[0107] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the principle of the present application shall be included within the protection scope of the present application.

Claims

1. An electrolyte, characterized in that: Based on the mass of the electrolyte, the electrolyte comprises: ethylene carbonate with a mass content of A%, methyl propyl carbonate with a mass content of B%, diethyl carbonate with a mass content of C%, ethyl propionate with a mass content of D%, and propyl propionate with a mass content of E%; Among them, 5≤A≤20, 10≤B≤20, and 0.1≤A / (B+C+D+E)≤0.

5.

2. The electrolyte according to claim 1, characterized in that The electrolyte satisfies at least one of the following conditions: (1)7≤A≤12； (2)13≤B≤17； (3)5≤C≤20； (4)20≤D≤40； (5)5≤E≤20； (6)0.15≤A / (B+C+D+E)≤0.

3.

3. The electrolyte according to claim 1 or 2, characterized in that Based on the mass of the electrolyte, the electrolyte comprises: adiponitrile with a mass content of F%, succinonitrile with a mass content of G%, and 1,3,6-hexanetrinitrile with a mass content of H%; 1≤F≤3, 2≤H≤4, and 1≤(F+G) / H≤1.

5.

4. The electrolyte according to claim 3, characterized in that The electrolyte includes a first component, wherein the first component includes 1H-imidazole-4-carbonitrile and / or 1,2-dimethyl-1H-imidazole-4,5-dicarbonitrile; Based on the mass of the electrolyte, the mass content of the first component is Y%; 0.5≤Y≤1; and / or, 0.125≤Y / H≤0.

5.

5. The electrolyte according to claim 1 or 2, characterized in that: The electrolyte includes fluoroethylene carbonate; based on the mass of the electrolyte, the mass content of the fluoroethylene carbonate is P%, 1≤P≤15; preferably, 4≤P≤8.

6. The electrolyte according to claim 1 or 2, characterized in that: The electrolyte includes 1,3-propane sultone; based on the mass of the electrolyte, the mass content of the 1,3-propane sultone is Q%, 2≤Q≤4.

7. The electrolyte according to claim 1 or 2, characterized in that: The electrolyte includes lithium hexafluorophosphate and a second lithium salt, wherein the second lithium salt includes lithium bis(oxalatoborate) and / or lithium tetraborate; Based on the mass of the electrolyte, the mass content of the second lithium salt is U%, and 0.3≤U≤0.

8.

8. The electrolyte according to claim 1 or 2, characterized in that: The electrolyte includes a second component, the second component including at least one of 1,2,4-triethylcyclohexane, 1,2,4-trimethylcyclohexane, or 1,4-dimethylcyclohexane; Based on the mass of the electrolyte, the mass content of the second component is X%, and 0.5≤X≤0.

8.

9. The electrolyte according to claim 1 or 2, characterized in that: The electrolyte includes a third component, and the third component includes at least one of 3,6-di-2-pyridyl-1,2,4,5-tetrazine, 3,6-di-4-pyridyl-1,2,4,5-tetrazine or 2,4,6-tris(4-pyridine)1,3,5-triazine; Based on the mass of the electrolyte, the mass content of the third component is Z%, and 0.3≤Z≤0.

8.

10. An electrochemical device, characterized in that: The invention comprises a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte comprises the electrolyte according to any one of claims 1 to 9.

11. An electronic device, characterized in that: An electrochemical device comprising the electrochemical device of claim 10.

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