Electrolyte additive composition, electrolyte, battery and electric device

Abstract

The invention discloses an electrolyte additive composition, an electrolyte, a battery and an electric device. The electrolyte additive composition comprises an impedance stabilizing additive and an isocyanate additive in a weight ratio of (0.1-0.8): 1. According to the electrolyte additive composition, the impedance stabilizing additive and the isocyanate additive are compounded, and the content ratio of the impedance stabilizing additive and the isocyanate additive is regulated, so that the stability of the impedance stabilizing additive in the electrolyte can be improved, the DCR of a battery cell is reduced, the stability of the DCR of the battery cell in the charging, discharging and storage processes is improved, and the service life of the battery cell is prolonged. Therefore, the RTE of the battery in the service period is improved. The electrolyte contains the electrolyte additive composition, and the battery contains the electrolyte. The electric device comprises the battery.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and particularly relates to an electrolyte additive composition, an electrolyte, a battery, and an electrical device using the same. Background Art

[0002] The electrolyte is one of the important components in a liquid battery. It is in direct contact with internal components such as the positive electrode, negative electrode, and separator of the liquid battery, and can significantly affect the electrochemical performance of the liquid battery.

[0003] In order to enhance the positive effect of the electrolyte on the electrochemical performance of the liquid battery, corresponding functional additives are often added to the electrolyte. For example, in order to improve the energy conversion efficiency (RTE) of the liquid battery during service, a type of additive that can reduce or stabilize the direct current internal resistance (DCR) of the liquid battery cell is often added to the electrolyte, so as to reduce or stabilize the impedance of the liquid battery during cycling and storage, thereby improving the RTE of the liquid battery throughout its life cycle.

[0004] However, it is found in the actual application process that these additives that can reduce or stabilize the DCR of the cell have low self-stability and are prone to decomposition. Moreover, the products of the reaction between the components contained in the electrolyte and trace amounts of water will also react with and consume these additives. This leads to an increase in the DCR of the liquid battery cell, thereby reducing the RTE of the liquid battery. Summary of the Invention

[0005] In view of the above problems, this application provides an electrolyte additive composition, an electrolyte, and a battery containing the electrolyte, so as to solve the technical problem that the energy conversion efficiency of the existing battery cell is reduced due to an increase in DCR.

[0006] In a first aspect, an embodiment of this application provides an electrolyte additive composition. The electrolyte additive composition in the embodiment of this application includes an impedance stabilizing additive and an isocyanate additive, and the weight ratio of the isocyanate additive to the impedance stabilizing additive is 0.1 - 0.8:1.

[0007] The electrolyte additive composition in the embodiment of this application can improve the stability of the impedance stabilizing additive in the electrolyte by compounding the impedance stabilizing additive and the isocyanate additive and regulating the content ratio of the two, thereby being able to reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage, and thus improve the RTE of the battery during service.

[0008] In some embodiments, the weight ratio of the isocyanate additive to the impedance stabilizing additive is 0.2 to 0.5:1. The compounding of the isocyanate additive and the impedance stabilizing additive within this ratio range can further improve the stability of the impedance stabilizing additive in the electrolyte, thereby further reducing the DCR of the battery cell and enhancing the stability of the DCR of the battery cell during charge and discharge and storage processes, and thus further improving the RTE of the battery during its service life.

[0009] In some embodiments, the isocyanate additive includes at least one of phenyl isocyanate, p-toluenesulfonyl isocyanate, hexamethylene diisocyanate, 4-fluorophenyl isocyanate, 2,4,6-trifluorophenyl isocyanate, 2,4,6-trimethoxy isocyanate, and diethoxyphosphino isocyanate.

[0010] These isocyanate additives can further improve the stability of the impedance stabilizing additive in the electrolyte, and will not cause an increase in the DCR of the battery cell due to the presence of these isocyanate additives. Therefore, the above-mentioned isocyanate additives can further reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage processes, thereby further improving the RTE of the battery during its service life.

[0011] In some embodiments, the isocyanate additive includes at least one of the following isocyanate additive compositions (1) to (5):

[0012] (1) A mixture including phenyl isocyanate and p-toluenesulfonyl isocyanate;

[0013] (2) A mixture including phenyl isocyanate and hexamethylene diisocyanate;

[0014] (3) A mixture including phenyl isocyanate and 2,4,6-trimethoxy isocyanate;

[0015] (4) A mixture including hexamethylene diisocyanate and p-toluenesulfonyl isocyanate;

[0016] (5) Any one of a mixture including 4-fluorophenyl isocyanate and p-toluenesulfonyl isocyanate.

[0017] The above-mentioned compound of two or more isocyanate additives can further reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage processes, thereby further improving the RTE of the battery during its service life.

[0018] In some embodiments, the impedance stabilizing additive includes at least one of methylene methanedisulfonate and ethylene sulfate.

[0019] After these types of impedance stabilizing additives are compounded with isocyanate additives in the above proportions, under the action of the isocyanate additives, they can further reduce the self-decomposition phenomenon of these types of impedance stabilizing additives in the electrolyte, especially in high-temperature environments. Moreover, under the action of the isocyanate additives acting as sacrificial agents and protective agents, they can further reduce the adverse effects of components in the electrolyte that are unfavorable to the stability of the impedance stabilizing additives, such as acidic substances, on the stability of these types of impedance stabilizing additives (including hydrolysis of the impedance stabilizing additives), thereby further improving the stability of these types of impedance stabilizing additives in the electrolyte to fully exert their functions, reducing the DCR of the battery cell and improving the stability of the DCR of the battery cell during charge and discharge and storage, and thus further improving the RTE of the battery during service.

[0020] In some embodiments, the electrolyte further includes an organic film-forming additive. This organic film-forming additive can participate in the formation of the SEI film in the battery cell, thereby improving the flexibility of the SEI film and reducing the brittleness of the SEI film, thus improving the stability of the SEI film during the charge and discharge process of the battery cell to improve the cycle performance of the battery cell.

[0021] In an embodiment, the weight ratio of the organic film-forming additive to the impedance stabilizing additive is (2 to 10):(0.5 to 5), optionally (3 to 7):(0.5 to 5).

[0022] In an embodiment, the organic film-forming additive includes an alkenyl ester additive.

[0023] These types and contents of organic film-forming additives can more effectively participate in the formation of SEI, further improve the toughness of SEI, improve the stability performance of the battery cell during charge and discharge, and improve the cycle performance of the battery cell. At the same time, it can also alleviate the increase in the DCR of the battery cell due to the addition of the organic film-forming additive.

[0024] In an exemplary embodiment, the alkenyl ester additive includes at least one of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, and methylene carbonate.

[0025] These types of alkenyl ester additives contain unsaturated double bonds and can participate in the formation of the SEI film during the charge and discharge process of the battery cell, improving the toughness and stability of the SEI film.

[0026] In some embodiments, the electrolyte further includes an inorganic carbonate. This inorganic carbonate can improve the stability of the SEI film contained in the battery cell, reduce the DCR of the battery cell, and improve the stability of the DCR, thereby further improving the cycle performance of the battery and the RTE during service.

[0027] In the examples, the weight ratio of the inorganic carbonate to the impedance stabilizing additive is (0.01 - 1):(0.5 - 5), optionally (0.05 - 0.5):(0.5 - 5).

[0028] In the examples, the inorganic carbonate includes alkali metal carbonate.

[0029] These types and contents of inorganic carbonates can fully exert the functions of the above-mentioned inorganic carbonates, improving the RTE and cycle performance of the battery during service.

[0030] In a second aspect, the embodiments of the present application provide an electrolyte. The electrolyte of the embodiments of the present application includes an organic solvent and an electrolyte dissolved in the organic solvent, and further includes the electrolyte additive composition of the embodiments of the present application mixed in the organic solvent.

[0031] The electrolyte of the embodiments of the present application can improve the stability of the impedance stabilizing additive in the electrolyte through the contained electrolyte additive composition, fully exert the function of the impedance stabilizing additive in the electrolyte, reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage, thereby improving the RTE of the battery during service. Further, through at least one component of the contained organic film-forming additive and inorganic carbonate, the stability of the SEI film during the charge and discharge of the battery cell can be improved to improve the cycle performance and conductivity of the battery cell.

[0032] In some embodiments, the content of the electrolyte additive composition in the electrolyte satisfies:

[0033] The concentration of the impedance stabilizing additive in the electrolyte is 0.5 wt% - 5 wt%, optionally 1 wt% - 3 wt%.

[0034] Controlling the electrolyte additive composition of the embodiments of the present application within this concentration range can improve the ability of the electrolyte additive composition of the embodiments of the present application to reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage, thereby improving the RTE of the battery during service and simultaneously improving the cycle performance of the battery.

[0035] In some embodiments, the organic solvent includes at least one of cyclic carbonates, chain carbonates, cyclic ethers, chain ethers, and sulfone compounds.

[0036] In exemplary examples, the cyclic carbonate includes at least one of ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone.

[0037] In the exemplary embodiment, the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl formate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate.

[0038] In the exemplary embodiment, the cyclic ether includes at least one of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, and 4-methyl-1,3-dioxolane.

[0039] In the exemplary embodiment, the chain ether includes at least one of dimethoxymethane, 1,2-dimethoxyethane, 1,2-dimethoxypropane, and diethylene glycol dimethyl ether.

[0040] The above-mentioned types of organic solvents have good stability, can effectively dissolve components such as electrolytes and additives, can assist the contained additives to play their roles, improve the DCR of the battery cell and the stability of DCR of the electrolyte additive composition in the above application example, thereby further improving the RTE of the battery during service, and at the same time can improve the cycle performance of the battery.

[0041] In some embodiments, the concentration of the electrolyte in the electrolyte solution is 7 wt% to 13 wt%, optionally 8 wt% to 11 wt%.

[0042] In some embodiments, the electrolyte includes at least one of lithium salts and sodium salts.

[0043] The above-mentioned sodium salt or lithium salt electrolyte has good stability and plays roles such as transferring ions, maintaining ion balance, and electrochemical stability in the electrolyte solution, improving the DCR stability of the single battery cell to improve the RTE of the battery during service, and at the same time can improve the cycle performance of the battery.

[0044] In a third aspect, the embodiment of the present application provides a battery. The battery in the embodiment of the present application includes the electrolyte solution in the embodiment of the present application.

[0045] Since the battery in the embodiment of the present application contains the electrolyte additive composition in the above application example, therefore, the DCR of the battery in the embodiment of the present application is low, and the DCR stability is good, improving the RTE of the battery during service, and at the same time also improving the cycle performance of the battery.

[0046] In a fourth aspect, the embodiment of the present application provides an electrical device. The electrical device in the embodiment of the present application includes the battery in the embodiment of the present application.

[0047] Since the electrical device according to the embodiment of the present application includes the battery according to the embodiment of the present application described above, the RTE of the power supply unit or the energy storage unit of the electrical device according to the embodiment of the present application is high, the cycle performance is good, the service life is long, and the standby or endurance time of the electrical device according to the embodiment of the present application is long.

[0048] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0050] Figure 1 is a schematic structural diagram of an embodiment of a battery cell according to the embodiment of the present application;

[0051] Figure 2 is Figure 1 an exploded view of the battery cell shown;

[0052] Figure 3 is a schematic structural diagram of an embodiment of a battery module according to the embodiment of the present application;

[0053] Figure 4 is an exploded structural diagram of a battery pack according to the embodiment of the application;

[0054] Figure 5 is a schematic diagram of an embodiment of an electrical device including the battery according to the embodiment of the present application as a power source.

[0055] The reference numerals in the specific embodiments are as follows:

[0056] 10 - battery cell, 11 - housing, 111 - inner wall, 12 - electrode assembly, 121 - large surface, 122 - top surface, 13 - cover plate;

[0057] 20 - battery module;

[0058] 30 - battery pack, 31 - upper box body, 32 - lower box body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] The embodiments of the technical solution of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0061] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0062] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0063] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0064] In the description of the embodiments of this application, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0065] In the description of the embodiments of this application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of this application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of this application.

[0066] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0067] With the continuous development of the application of batteries as power batteries and energy storage batteries, higher requirements are put forward for the energy conversion efficiency (RTE) and cycle life of batteries. Especially when the battery is used as an energy storage battery, it is often required to have a service cycle of up to 10 years or even more than 20 years, which puts forward higher requirements for the RTE and cycle life of the battery.

[0068] The electrolyte is one of the important components in a liquid battery. It is in direct contact with internal components such as the positive electrode, negative electrode, and separator in the battery and can significantly affect the electrochemical performance of the liquid battery. Therefore, in order to improve the positive effect of the electrolyte on the electrochemical performance of the liquid battery, corresponding functional additives are often added to the electrolyte. For example, in order to improve the energy conversion efficiency (RTE) of the liquid battery during service, a type of impedance stabilizing additive that can reduce or stabilize the direct current internal resistance (DCR) of the liquid battery cell is often added to the electrolyte, so as to reduce and stabilize the impedance of the liquid battery during cycling and storage, thereby improving the RTE of the liquid battery during its entire life cycle.

[0069] However, in the actual application process of liquid batteries, when the battery is charged and discharged for a long time, especially in a high-temperature environment such as high-temperature standing, the self-stability of this type of impedance stabilizing additive used to reduce or stabilize the DCR of the battery cell will decrease, and decomposition will occur. Moreover, the electrolyte contains electrolytes that will react with trace amounts of water, especially in a high-temperature environment, and acidic substances will be generated. The generation of this acidic substance will cause the impedance stabilizing additive contained in the electrolyte to hydrolyze. Therefore, phenomena such as the self-decomposition and hydrolysis of the impedance stabilizing additive reduce the content of the impedance stabilizing additive in the electrolyte, which will cause the DCR of the battery cell to increase, resulting in a low RTE of the battery during service.

[0070] Although some other additives are reported in the prior art to replace and assist the currently commonly used impedance stabilizing additives in the hope of improvement, the effect of reducing or stabilizing the DCR of the battery cell is not obvious. Sometimes, due to the excessive addition of these additives, the DCR of the battery cell will even increase.

[0071] In order to effectively reduce the DCR of battery cells and improve the stability of DCR, thereby improving the RTE of the battery during service. Through research, an electrolyte additive composition is proposed. By compounding additives such as isocyanate additives and impedance stabilizing additives and adjusting the content ratio of the corresponding additives, it is possible to effectively reduce phenomena such as self-decomposition and hydrolysis of the impedance stabilizing additive, thereby effectively improving the stability of the impedance stabilizing additive in the electrolyte, thereby being able to significantly reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell, thereby significantly improving the RTE of the battery during service.

[0072] Based on the above research, the embodiments of this application propose the following technical solutions.

[0073] [Electrolyte Additive Composition]

[0074] In a first aspect, the embodiments of this application provide an electrolyte additive composition. The electrolyte additive composition of the embodiments of this application includes an impedance stabilizing additive and an isocyanate additive, wherein the weight ratio of the isocyanate additive to the impedance stabilizing additive is 0.1 - 0.8:1.

[0075] In the electrolyte additive composition of the embodiments of this application, the impedance stabilizing additive refers to a type of electrolyte additive that can reduce the direct current internal resistance (DCR) of the battery cell, or further can play a role in stabilizing the DCR of the battery cell to avoid a significant increase in the DCR of the battery cell. The isocyanate additive refers to a type of compound containing an isocyanate group (-NCO).

[0076] Thus, after the electrolyte additive composition of the embodiments of the present application is added to the electrolyte as an additive, the impedance stabilizing additive contained therein can reduce the DCR of the battery cell, and can also effectively improve the stability of the DCR of the battery cell during charge and discharge and storage. The content of the isocyanate additive contained therein and its content ratio with the impedance stabilizing additive can, on the one hand, improve the stability of the impedance stabilizing additive itself in the electrolyte, especially the thermal stability, and reduce its self-decomposition phenomenon during charge and discharge or storage of the battery cell; on the other hand, the electrolyte contained in the electrolyte will react with trace water, especially easily react in a high-temperature environment, and generate acidic substances. The generation of the acidic substances will cause hydrolysis of the impedance stabilizing additive contained in the electrolyte; at this time, the isocyanate additive can also act as a sacrificial agent or a protective agent, and it can react with components that are unfavorable to the stability of the impedance stabilizing additive in the electrolyte, such as the acidic substances, to reduce the content of components that are unfavorable to the stability of the impedance stabilizing additive, such as acidic substances, thereby reducing the adverse effects (including hydrolysis of the impedance stabilizing additive) of these components, such as acidic substances, on the stability of the impedance stabilizing additive, so as to improve the stability of the impedance stabilizing additive in the electrolyte, thereby giving full play to the role of the impedance stabilizing additive in the electrolyte, so as to reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage; secondly, controlling the compounding ratio of the isocyanate and the impedance stabilizing additive within the range of 0.1-0.8:1 described above will not cause the DCR in the battery cell to increase due to the presence of additives such as isocyanate. Therefore, the electrolyte additive composition of the embodiments of the present application can improve the stability of the impedance stabilizing additive in the electrolyte and improve the functions of the impedance stabilizing additive in reducing the DCR of the battery cell and improving the stability of the DCR of the battery cell during charge and discharge and storage by compounding the impedance stabilizing additive and the isocyanate additive and regulating the content ratio of the two, thereby improving the RTE of the battery during service.

[0077] In some embodiments, the weight ratio of the isocyanate additive to the impedance stabilizing additive contained in the electrolyte additive composition of the embodiments of the present application is 0.2 to 0.5:1. In the demonstration example, based on the weight ratio of the isocyanate additive to the impedance stabilizing additive being 0.2 to 0.8:1, which can be optionally 0.2 to 0.5:1, the weight ratio of the isocyanate additive to the impedance stabilizing additive can be typical but non-limiting ratios such as 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, or a range between any two ratio values. Further regulating the content of the isocyanate within this range can further improve the stability of the impedance stabilizing additive itself in the electrolyte and enhance the reaction between the isocyanate additive and adverse components such as acidic substances generated in the electrolyte, thereby further reducing the adverse effects of these adverse components such as acidic substances on the stability of the impedance stabilizing additive. Therefore, the compounding of the isocyanate additive and the impedance stabilizing additive within the above ratio range can further improve the stability of the impedance stabilizing additive in the electrolyte, thereby further reducing the DCR of the battery cell and enhancing the stability of the DCR of the battery cell during charge and discharge and storage processes, and thus further improving the RTE of the battery during service.

[0078] In some embodiments, the impedance stabilizing additive contained in the electrolyte additive composition of the embodiments of the present application includes at least one of methylene methanedisulfonate (MMDS) and vinylene sulfate (DTD). These types of impedance stabilizing additives can reduce the DCR of the battery cell and have relatively high stability compared to other additives with the same function, and the amount of self-decomposition is relatively reduced, thereby improving the stability of the DCR of the battery cell during charge and discharge and storage processes. When compounded with the isocyanate additive in the above ratio, under the action of the isocyanate additive, the self-decomposition phenomenon of these types of impedance stabilizing additives in the electrolyte, especially in a high-temperature environment, can be further reduced, and the stability of these types of impedance stabilizing additives in the electrolyte, especially in a high-temperature environment, can be further improved; moreover, under the action of the isocyanate additive acting as a sacrificial agent and a protective agent, the adverse effects of components such as acidic substances in the electrolyte that are unfavorable to the stability of the impedance stabilizing additive on the stability of these types of impedance stabilizing additives (including hydrolysis of the impedance stabilizing additive) can be further reduced, thereby further improving the stability of these types of impedance stabilizing additives in the electrolyte to fully exert their functions, to reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage processes, and thus further improve the RTE of the battery during service.

[0079] In the demonstration example, when the impedance stabilizing additive includes methylene methanedisulfonate, the methylene methanedisulfonate can reduce the DCR of the battery cell and improve the DCR stability of the battery during normal charge and discharge and storage. However, during the long-term charge and discharge process, especially in a high-temperature environment, the methylene methanedisulfonate still has a certain degree of self-decomposition phenomenon, generating paraformaldehyde; and in a high-temperature environment, the electrolyte reacts with trace water to generate acidic substances, such as lithium hexafluorophosphate (LiPF 6 ) is prone to react with trace water to generate hydrofluoric acid, and methylene methanedisulfonate is easily hydrolyzed by the acidic substance, thereby further reducing the content of methylene methanedisulfonate. Due to the reduction of the content of methylene methanedisulfonate in the electrolyte, the DCR of the battery cell increases, and due to the increase of the DCR of the battery cell, the RTE of the battery during service decreases. The presence of isocyanate, that is, the compounding of isocyanate with impedance stabilizing additives including methylene methanedisulfonate, can effectively reduce the self-decomposition, especially high-temperature decomposition and hydrolysis phenomenon of methylene methanedisulfonate, thereby further improving the stability of impedance stabilizing additives including methylene methanedisulfonate in the electrolyte to fully exert its function, to reduce the DCR of the battery cell and improve the DCR stability of the battery cell during charge and discharge and storage, thereby further improving the RTE of the battery during service.

[0080] In some embodiments, the isocyanate additives contained in the electrolyte additive composition of the embodiments of the present application include at least one of phenyl isocyanate (PI), p-toluenesulfonyl isocyanate (PTSI), hexamethylene diisocyanate (HDI), 4-fluorophenyl isocyanate (FPI), 2,4,6-trifluorophenyl isocyanate (TFPI), 2,4,6-trimethoxy isocyanate (TMPI), and diethoxyphosphino isocyanate (DOPI). Selecting these isocyanate additives to act with the impedance stabilizer can further improve the stability of the impedance stabilizing additive in the electrolyte and reduce its self-decomposition phenomenon during the charge and discharge or storage of the battery cell; at the same time, these isocyanate additives are more likely to react with the acidic substances generated by the reaction of the electrolyte and trace water to consume the content of the acidic substances in the electrolyte, thereby further reducing the hydrolysis of the impedance stabilizing additive caused by the acidic substances. Thus, these isocyanate additives can further improve the stability of the impedance stabilizing additive in the electrolyte and will not cause an increase in the DCR of the battery cell due to the presence of these isocyanate additives. Therefore, the above-mentioned isocyanate additives can further reduce the DCR of the battery cell and improve the DCR stability of the battery cell during charge and discharge and storage, thereby further improving the RTE of the battery during service.

[0081] In some embodiments, the isocyanate additives in the above embodiments may be a combination of two or more of the following components:

[0082] In the embodiment, the isocyanate additive comprises the following compounded components:

[0083] Composition A1: Comprising a mixture of phenyl isocyanate (PI) and p-toluenesulfonyl isocyanate (PTSI); in the embodiment, the weight ratio of PI to PTSI may be, but is not limited to, 1:1, and specifically, of course, other mixing ratios may also be possible.

[0084] Composition A2: Comprising a mixture of phenyl isocyanate (PI) and hexamethylene diisocyanate (HDI); in the embodiment, the weight ratio of PI to HDI may be, but is not limited to, 1:1, and specifically, of course, other mixing ratios may also be possible.

[0085] Composition A3: Comprising a mixture of phenyl isocyanate (PI) and 2,4,6-trimethoxyphenyl isocyanate (TFPI); in the embodiment, the weight ratio of PI to TFPI may be, but is not limited to, 1:1, and specifically, of course, other mixing ratios may also be possible.

[0086] Composition A4: Comprising a mixture of hexamethylene diisocyanate (HDI) and p-toluenesulfonyl isocyanate (PTSI); in the embodiment, the weight ratio of HDI to PTSI may be, but is not limited to, 1:1, and specifically, of course, other mixing ratios may also be possible.

[0087] Composition A5: Comprising a mixture of 4-fluorophenyl isocyanate (FPI) and p-toluenesulfonyl isocyanate (PTSI); in the embodiment, the weight ratio of FPI to PTSI may be, but is not limited to, 1:1, and specifically, of course, other mixing ratios may also be possible.

[0088] In the above embodiments, the isocyanate additives are compounded with two or more components, which can further improve the stability of the impedance stabilizing additive in the electrolyte and reduce its self-decomposition during charge and discharge or storage of the battery cell; at the same time, it can also further reduce the hydrolysis of the impedance stabilizing additive caused by adverse components such as acidic substances generated in the electrolyte. The above-mentioned compound of two or more isocyanate additives can further reduce the negative electrode interface impedance and the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage, thereby further improving the RTE of the battery during service.

[0089] In some embodiments, the electrolyte additive composition of the embodiments of the present application may further include an organic film-forming additive.

[0090] Among them, the organic film-forming additive refers to an additive that can promote or further participate in the formation of a passivation film on the electrodes in the battery cell in the electrolyte and can improve the relevant mechanical properties of the passivation film. The passivation film generally refers to a solid electrolyte film, abbreviated as SEI (Solid Electrolyte Interface) film. The presence of the organic film-forming additive can effectively improve the cycle performance of the battery cell. Specifically, it can participate in the formation of the SEI film in the battery cell, thereby improving the flexibility of the SEI film and reducing the brittleness of the SEI film, thus improving the stability of the SEI film during the charge and discharge process of the battery cell.

[0091] In the examples, the weight ratio of the organic film-forming additive to the impedance stabilizing additive is (2 - 10):(0.5 - 5), optionally (3 - 7):(0.5 - 5). In the demonstration examples, the weight ratios of the organic film-forming additive to the impedance stabilizing additive are typical but non-limiting ratios such as 2:0.5, 3:0.5, 4:0.5, 5:0.5, 6:0.5, 7:0.5, 8:0.5, 9:0.5, 10:0.5, 2:5, 3:5, 4:5, 5:5, 6:5, 7:5, 8:5, 9:5, 10:5, etc., or the range between any two ratio values. The organic film-forming additive within this ratio range can effectively promote or further promote the formation of SEI in the battery cell, improve its mechanical properties, enhance the stability of the SEI film, and improve the cycle performance of the battery cell, while keeping the DCR and RTE of the battery cell relatively stable.

[0092] In the examples, the above-mentioned organic film-forming additive includes vinyl ester-based additives. These types of organic film-forming additives can participate in the formation of SEI more effectively, further improve the toughness of SEI, improve the stability of the battery cell during the charge and discharge process, and thus improve the cycle performance of the battery cell. At the same time, it can also alleviate the increase in the DCR of the battery cell caused by the addition of the organic film-forming additive.

[0093] In the demonstration examples, the vinyl ester-based additive may include at least one of vinylene carbonate (VC), fluoroethylene carbonate (FEC), vinyl ethylene carbonate (VEC), and methylene ethylene carbonate (MEC). These types of vinyl ester-based additives contain unsaturated double bonds and can participate in the formation of the SEI film during the charge and discharge process of the battery cell, improving the toughness and stability of the SEI film. At the same time, these types of vinyl ester-based additives can also reduce the adverse impact on the DCR of the battery cell.

[0094] In addition, it was found in the research that when the electrolyte additive composition of the embodiment of the present application contains the above-mentioned organic film-forming additive, or when the electrolyte contains the organic film-forming additive, after the electrolyte additive composition of the embodiment of the present application is added to the electrolyte, when the impedance stabilizing additive contained therein undergoes self-decomposition, the decomposition products will also cause the above-mentioned organic film-forming additive to undergo a polymerization reaction or the products will participate in the polymerization reaction of the above-mentioned organic film-forming additive, resulting in a decrease or even failure of the content of the organic film-forming additive, thus affecting the formation and stability of the SEI film. At the same time, when the acidic substance generated by the reaction of the electrolyte contained in the electrolyte with trace water, if the isocyanate additive contained in the electrolyte additive composition of the present application does not react with the acidic substance in time or is not completely consumed by the reaction, then the remaining acidic substance will not only cause phenomena such as hydrolysis of the above-mentioned impedance stabilizing additive, but also cause an increase in the acidity, chromaticity, etc. of the electrolyte, thus easily leading to the deterioration and failure of the electrolyte. Therefore, when the self-decomposition of the above-mentioned impedance stabilizing additive and the reaction of the electrolyte contained in the electrolyte with trace water occur, the cycle stability of the battery cell is reduced.

[0095] For example, when the above-mentioned impedance stabilizing additive contains methylene methane disulfonate, the self-decomposition of methylene methane disulfonate will produce paraformaldehyde, which is likely to reduce and polymerize the organic film-forming additive contained in the electrolyte, resulting in a decrease or even failure of the content of the organic film-forming additive, thus affecting the formation and stability of the SEI film. When the acidic substance generated by the reaction of the electrolyte with trace water also causes an increase in the acidity, chromaticity, etc. of the electrolyte, it is easy to lead to the deterioration and failure of the electrolyte. Therefore, when the self-decomposition of methylene methane disulfonate and the reaction of the electrolyte contained in the electrolyte with trace water occur, the cycle stability of the battery cell will be reduced.

[0096] To alleviate the phenomenon of reduced cycle stability of the battery cell caused by the self-decomposition of the above-mentioned impedance stabilizing additive and the reaction of the electrolyte contained in the electrolyte with trace water. In one embodiment, the electrolyte additive composition of the embodiments of the present application may further include inorganic carbonate. The presence of this inorganic carbonate can, on the one hand, effectively act as a protective agent to protect the above-mentioned organic film-forming additives including vinyl ester-containing additives, etc., and alleviate the failure of the above-mentioned organic film-forming additives due to the polymerization of the products of the self-decomposition of the impedance stabilizing additive. For example, when the above-mentioned organic film-forming additives include vinyl ester-containing additives and the impedance stabilizing additive includes at least one of methylene methanedisulfonate (MMDS) and vinylene sulfate (DTD), this inorganic carbonate can alleviate the reduction and polymerization failure of the vinyl ester-containing additive reduced by at least one of MMDS and DTD, thereby improving the stability of the organic film-forming additive to improve the cycle performance of the cell. On the other hand, it can inhibit the formation of organic components such as lithium alkyl carbonate contained in the SEI film in the cell and promote the formation of highly conductive inorganic SEI film components, such as LiSO 4 / LiCO 3 etc., which can significantly improve the conductivity of the SEI film; moreover, the addition of this inorganic carbonate, its cation can increase the ionic conductivity of the electrolyte, and can also reduce the phenomenon of increased DCR of the battery cell caused by additives including the above-mentioned isocyanate-containing additives, etc. Therefore, this inorganic carbonate can improve the stability of the SEI film contained in the battery cell, reduce the DCR of the battery cell and improve the stability of the DCR, thereby further improving the cycle performance of the battery and the RTE during service.

[0097] In the embodiments, the weight ratio of the above inorganic carbonate to the impedance stabilizing additive can be (0.01 - 1):(0.5 - 5), optionally (0.05 - 0.5):(0.5 - 5). In the exemplary embodiments, the weight ratio of the inorganic carbonate to the impedance stabilizing additive can be 0.01:0.5, 0.05:0.5, 0.1:0.5, 0.2:0.5, 0.3:0.5, 0.4:0.5, 0.5:0.5, 0.6:0.5, 0.7:0.5, 0.8:0.5, 0.9:0.5, 1:0.5, 0.01:5, 0.05:5, 0.1:5, 0.2:5, 0.3:5, 0.4:5, 0.5:5, 0.6:5, 0.7:5, 0.8:5, 0.9:5, 1:5 and other typical but non-limiting ratios or the ranges between any two ratio values. The inorganic carbonate within this ratio range can, on the basis of fully exerting the functions of the above inorganic carbonate, further improve the protection of organic film-forming additives such as the above-mentioned vinyl ester-containing additives, enhance the stability of the organic film-forming additives in the electrolyte, and thus further improve the cycling performance of the battery cell. At the same time, it further reduces the DCR and the stability of DCR of the battery cell, thereby further improving the RTE of the battery during service.

[0098] In the exemplary embodiments, the above inorganic carbonate can include alkali metal carbonates. For example, the alkali metal carbonate can include at least one of lithium carbonate and sodium carbonate. Additionally, the inorganic carbonate can be selected according to the type of the electrolyte. For example, when it is a lithium-ion electrolyte, the inorganic carbonate can be an inorganic carbonate including lithium carbonate; when it is a sodium-ion electrolyte, the inorganic carbonate can be an inorganic carbonate including sodium carbonate. These inorganic carbonates can fully exert the functions of the above inorganic carbonate and improve the RTE and cycling performance of the battery during service.

[0099] The preparation method of the electrolyte additive composition in each of the above embodiments can be subjected to mixing treatment according to the components it contains, such as mixing treatment according to the types and content ratio relationships of the components contained above. Of course, the components can be separately set according to the types and content ratio relationships of the components contained above, and when preparing the electrolyte, they are added to the solvent in proportion.

[0100] [Electrolyte]

[0101] In a second aspect, the embodiments of the present application further provide an electrolyte. The electrolyte in the embodiments of the present application includes an organic solvent and an electrolyte dissolved in the organic solvent, and further includes an additive mixed in the organic solvent. Among them, the additive includes the above electrolyte additive composition of the present application.

[0102] In the electrolyte of the embodiment of the present application, it can serve as a carrier for conducting ions between the positive electrode and the negative electrode. The organic solvent serves as the solvent carrier of the electrolyte, and the electrolyte is an inorganic salt or an organic salt that plays roles such as transferring ions and maintaining ion balance in the electrolyte. The additive is a component other than the organic solvent and the electrolyte components used to improve the related performance of the battery cell, such as improving film formation, conductivity and other performances. It is understood that the additive is mixed with the organic solvent and at least dissolved in the organic solvent. The additive includes that the electrolyte additive composition of the above-mentioned application can be, for example, an isocyanate additive and an impedance stabilizing additive with a weight ratio of 0.1 to 0.8:1 as described above, and can further include at least one additive such as the above-mentioned organic film-forming additive, inorganic carbonate, etc.

[0103] Since the electrolyte of the embodiment of the present application contains the electrolyte additive composition of the above-mentioned application, therefore, the above-mentioned isocyanate additive and impedance stabilizing additive contained therein, or at least one additive such as the above-mentioned organic film-forming additive, inorganic carbonate, etc. further contained therein are dissolved in the organic solvent. In this way, the above-mentioned impedance stabilizing additive can reduce the DCR of the battery cell, and can also effectively improve the stability of the DCR of the battery cell during charge and discharge and storage. The above-mentioned isocyanate additive can improve the stability of the impedance stabilizing additive itself in the electrolyte and reduce its self-decomposition phenomenon during charge and discharge or storage of the battery cell; at the same time, it acts as a sacrificial agent or a protective agent, and it can react with components in the electrolyte that are unfavorable to the stability of the impedance stabilizing additive, such as the generated acidic substances, to reduce the hydrolysis and other phenomena of the impedance stabilizing additive, so as to improve the stability of the impedance stabilizing additive in the electrolyte, thereby giving full play to the role of the impedance stabilizing additive in the electrolyte, reducing the DCR of the battery cell and improving the stability of the DCR of the battery cell during charge and discharge and storage, thereby improving the RTE of the battery during service.

[0104] When the electrolyte of the embodiment of the present application further contains the above-mentioned organic film-forming additive, the organic film-forming additive can effectively participate in the formation of the SEI film in the battery cell in the electrolyte of the embodiment of the present application, thereby improving the flexibility of the SEI film and reducing the brittleness of the SEI film, thereby improving the stability of the SEI film during the charge and discharge process of the battery cell to improve the cycle performance of the battery cell.

[0105] When the electrolyte in the embodiment of the present application further contains the inorganic carbonate described above, the organic film-forming additive can effectively act as a protective agent in the electrolyte of the embodiment of the present application, protect the organic film-forming additives such as vinyl ester additives in the electrolyte, and relieve the polymerization of the organic film-forming additives caused by the decomposition products of the impedance stabilizing additive itself, thereby improving the stability of the organic film-forming additive and enhancing the cycle performance of the battery cell. At the same time, it can inhibit the formation of organic components such as lithium alkyl carbonate in the SEI film in the battery cell, promote the formation of highly conductive inorganic SEI film components and increase the ionic conductivity of the electrolyte, reduce the DCR of the battery cell and improve the stability of the DCR, so as to further improve the cycle performance of the battery and the RTE during service.

[0106] In some embodiments, the content of the electrolyte additive composition in the electrolyte of the embodiment of the present application can be added according to the following proportional relationship:

[0107] The concentration of the impedance stabilizing additive contained in the electrolyte additive composition of the embodiment of the present application in the electrolyte is 0.5 wt% to 5 wt%, optionally 1 wt% to 3 wt%. In exemplary embodiments, the concentration of the impedance stabilizing additive in the electrolyte can be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt% and other typical but non-limiting concentrations or the range between any two concentration values. Controlling the electrolyte additive composition of the embodiment of the present application within this concentration range can improve the ability of the electrolyte additive composition of the embodiment of the present application to reduce the DCR of the battery cell and improve the stability of the DCR of the battery cell during charge and discharge and storage, thereby improving the RTE of the battery during service and simultaneously improving the cycle performance of the battery.

[0108] Based on the weight ratio relationship between the isocyanate additive and the impedance stabilizing additive in the electrolyte additive composition of the embodiment of the present application, when the concentration of the impedance stabilizing additive in the electrolyte of the embodiment of the present application is 0.5 wt% to 5 wt%, then the concentration of the organic film-forming additive in the electrolyte of the embodiment of the present application is 2 wt% to 10 wt%, optionally 3 wt% to 7 wt%; the concentration of the inorganic carbonate in the electrolyte of the embodiment of the present application is 0.01 wt% to 1 wt%, optionally 0.05 wt% to 0.5 wt%.

[0109] In some embodiments, the organic solvent contained in the electrolyte of the embodiment of the present application may include at least one of cyclic carbonates, chain carbonates, cyclic ethers, chain ethers, lactone compounds, nitrile compounds, and sulfone compounds.

[0110] In exemplary embodiments, the cyclic carbonate may include at least one of ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone.

[0111] In the exemplary embodiment, the chain carbonate may include at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl formate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate.

[0112] In the exemplary embodiment, the cyclic ether may include at least one of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, and 4-methyl-1,3-dioxolane.

[0113] In the exemplary embodiment, the chain ether may include at least one of dimethoxymethane, 1,2-dimethoxyethane, 1,2-dimethoxypropane, and diethylene glycol dimethyl ether.

[0114] The above-mentioned organic solvent has good stability, can effectively dissolve components such as electrolytes and additives, and can assist the contained additives to play their roles, such as improving the DCR of the battery cell and the stability of the DCR by the electrolyte additive composition of the embodiment of the present application, thereby further improving the RTE of the battery during service and improving the cycle performance of the battery at the same time.

[0115] In some embodiments, the concentration of the electrolyte contained in the electrolyte of the embodiment of the present application in the electrolyte of the embodiment of the present application is 7 wt% to 13 wt%, optionally 8 wt% to 11 wt%. In the exemplary embodiment, the concentration of the electrolyte in the electrolyte may be a typical but non-limiting concentration or a range between any two concentration values.

[0116] In some embodiments, the electrolyte contained in the electrolyte of the embodiment of the present application may include at least one of lithium salts and sodium salts. Specifically, it can be selected according to the type of battery monomer. For example, when it is a battery monomer, the electrolyte can be a sodium salt, and of course, an appropriate lithium salt can also be contained. The addition of the lithium salt can adjust the stability of the SEI film; when it is a lithium battery monomer, the electrolyte can be a lithium salt.

[0117] In the exemplary embodiment, when the electrolyte includes a lithium salt, the lithium salt may include at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate, and lithium difluoro(oxalato)borate. When the lithium salt includes lithium hexafluorophosphate, the molar proportion of the lithium hexafluorophosphate in the lithium salt is 0.3 to 1.0.

[0118] When the electrolyte includes a sodium salt, the sodium salt may include at least one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, sodium sulfide, sodium chloride, sodium fluoride, sodium sulfate, sodium carbonate, sodium phosphate, sodium nitrate, sodium difluoro(oxalato)borate, sodium pyrophosphate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, trisodium citrate, sodium metaborate, sodium borate, sodium molybdate, sodium tungstate, sodium bromide, sodium nitrite, sodium iodate, sodium iodide, sodium silicate, sodium lignosulfonate, sodium oxalate, sodium aluminate, sodium methylsulfonate, sodium acetate, sodium dichromate, sodium hexafluoroarsenate, sodium tetrafluoroborate, sodium perchlorate, sodium bis(trifluoromethanesulfonyl)imide.

[0119] The above sodium salt or lithium salt electrolyte has good stability and plays roles such as good ion transfer and ion balance maintenance and electrochemical stability in the electrolyte solution, improving the DCR stability of the battery single cell core and thus improving the RTE of the battery during service. At the same time, it can improve the cycle performance of the battery.

[0120] The preparation method of the electrolyte in each of the above embodiments can add components such as the electrolyte and additives to an organic solvent in proportion according to the components it contains and perform a mixing treatment to prepare an electrolyte with each component evenly dispersed. In the embodiments, the method of adding components such as the electrolyte and additives to the organic solvent in proportion can be carried out according to the current preparation methods of lithium ion electrolyte or sodium ion electrolyte.

[0121] [Battery]

[0122] In a third aspect, the embodiments of the present application further provide a battery.

[0123] In the embodiments, the battery of the embodiments of the present application may include any one of a battery single cell, a battery module, and a battery pack.

[0124] Battery single cell:

[0125] A battery single cell, also known as a cell core, refers to a battery outer package and electrode assemblies and an electrolyte encapsulated within the battery outer package. The number of electrode assemblies contained in the battery single cell can be one or more, which can be adjusted according to actual needs. The electrode assemblies are immersed in the electrolyte.

[0126] The electrolyte of the battery single cell:

[0127] The electrolyte contained in the battery single cell of the embodiments of the present application is the electrolyte of the embodiments of the present application above, specifically containing the electrolyte additive composition of the embodiments of the present application above. To save space, the description of this electrolyte will not be repeated here.

[0128] Since the battery cell of the embodiment of the present application contains the electrolyte additive composition described above, the DCR of the battery cell of the embodiment of the present application is low, and the DCR stability is good, which improves the RTE of the battery cell during service and also improves the cycling performance of the battery cell.

[0129] Outer packaging of the battery cell:

[0130] In the embodiment, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.; it can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. The shape of the outer packaging can be cylindrical, square, or any other shape. This outer packaging shape gives the shape of the battery cell, so the shape of the battery cell can also be cylindrical, square, or any other shape corresponding to the outer packaging. In the demonstration example, the battery cell can be the Figure 1 battery cell 10 with a square structure as shown.

[0131] In some embodiments, as Figure 2 shown, the outer packaging of the battery cell 10 may include a housing 11 and a cover plate 13. The housing 11 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 is used to cover the opening to close the receiving cavity. One or more electrode assemblies 12 are encapsulated in the receiving cavity.

[0132] Electrode assembly of the battery cell:

[0133] In the embodiment, the electrode assembly contained in the battery cell generally includes a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet and the negative electrode sheet are alternately stacked, and the separator is stacked between the positive electrode sheet and the negative electrode sheet to play a role of isolation, separating the positive electrode and the negative electrode. The positive electrode sheet, the separator layer, and the negative electrode sheet can form a stacked electrode assembly through a stacking process, or can form a wound core electrode assembly through a winding process. The electrode assembly containing the separator is placed in the outer packaging, electrolyte is injected and infiltrates the electrode assembly, and the battery cell is obtained after encapsulation.

[0134] Positive electrode sheet of the electrode assembly:

[0135] In the embodiment, the positive electrode sheet contained in the electrode assembly includes a positive electrode current collector and a positive electrode active material layer combined on at least one surface of the positive electrode current collector.

[0136] In an embodiment, the positive electrode current collector contained in the positive electrode sheet may include, but is not limited to, a metal current collector, a carbon current collector, a conductive resin current collector, a composite current collector of metal and resin, etc. More specifically, for example, aluminum, copper, nickel, titanium, iron and their respective alloys, stainless steel, carbon fiber, carbon nanotube (CNT), graphite, etc. In an embodiment, the current collector may also be a dense film layer or a film layer with a porous structure. In an embodiment, the current collector may be, but is not limited to, aluminum foil or porous aluminum foil, etc.

[0137] In an embodiment, the positive electrode active material layer contained in the positive electrode sheet may be combined on one surface of the positive electrode current collector or may be combined on two opposite surfaces of the positive electrode current collector at the same time. When the surface layer of the positive electrode current collector contains a porous structure or the positive electrode current collector itself is a porous structure, the positive electrode active material layer may be at least partially embedded in the current collector.

[0138] In an embodiment, the mass content of the positive electrode active material contained in the positive electrode active material layer may be 90% to 98%, optionally 92% to 96%. In an exemplary example, it may be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc., typical but non-limiting contents or a range between any two content values. The positive electrode active material within this content range can effectively improve the energy density of the positive electrode sheet.

[0139] In an embodiment, the positive electrode active material may include a sodium ion positive electrode active material or a lithium ion positive electrode active material. When containing a sodium ion positive electrode active material, the battery monomer in the embodiment of the present application may be a sodium battery monomer. At this time, the electrolyte contained in the corresponding sodium battery monomer is a sodium ion electrolyte. When containing a lithium ion positive electrode active material, the battery monomer in the embodiment of the present application may be a lithium battery monomer. At this time, the electrolyte contained in the corresponding lithium battery monomer is a lithium ion electrolyte.

[0140] In an exemplary example, the sodium ion positive electrode active material may include one or more of sodium layered oxides, polyanion compounds, and Prussian blue compounds. For example, the layered oxide may include Na x MO 2 , where M = one or more of Fe, Mn, Ni, Co, Cr, Sc, Ti, V, Cr, Cu, Zn, 0.4 ≤ x ≤ 1. For example, NaFe 0.33 Mn 0.33 Ni 0.33 O 2 , NaFe 0.5 Ni 0.5 O 2 , Na 0.6 MnO 2 , Na 0.44 MnO 2 、Na0.65 Mn 0.75 Ni 0.25 O 2 、NaNi 0.5 Mn 0.5 O 2 、Na 0.78 Ni 0.23 Mn 0.69 O 2 、NaVO 2 、NaFeO 2 、Na 0.7 CoO 2 etc. The polyanion compounds can include one or more of phosphates, pyrophosphates, sulfate-based, anion-doped types, such as olivine-type NaFePO 4 、Na 2 FeP 2 O 7 、NaFePO 4 F、Na 3 V 2 (PO 4 ) 3 、NaFeSO 4 and one or more of them. The Prussian blue compounds can include Na 0.61 Fe[Fe(CN) 6 0.94 、BR-FeHCF、Na 1.48 Ni[Fe(CN) 6 0.89 、NaNi 0.05 Mn 0.95 [Fe(CN) 6 and one or more of them.

[0141] In the exemplary embodiment, the lithium-ion cathode active material can include but is not limited to LiFePO 4 、Li 3 V 2 (PO 4 ) 3 、LiMn 2 O 4 、LiMnO 2 、LiNiO 2 、LiCoO 2 、LiVPO 4 F、LiFeO 2 、Li 1+x L 1-y-z M 1 y M 2 z O 2 ​​One or more of them, where -0.1 ≤ x ≤ 0.2, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ y + z ≤ 1, L, M 1 , M 2 Each independently includes one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Mg, Ga.

[0142] These types of sodium-ion or lithium-ion cathode active materials have a high specific capacity, or further have high structural stability and good cycling performance.

[0143] In the examples, in addition to the cathode active material components described above, the cathode active material layer contained in the above cathode sheet generally further includes components such as a binder and a conductive agent. The binder can enhance the mechanical properties between the cathode active material layer itself and the current collector. The conductive agent can effectively improve the conductivity of the cathode, such as reducing the resistance of the cathode.

[0144] In the examples, the mass content of the binder contained in the above cathode active material layer can be 0.5% to 5%, optionally 1% to 3%. In the exemplary examples, it can be 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3% and other typical but non-limiting contents or the range between any two content values.

[0145] In the examples, the binder can include one or more of oil-soluble binders, water-soluble binders, emulsion binders, etc. In the exemplary examples, the oil-soluble binder can include one or more of polyvinylidene fluoride, polyimide, polytetrafluoroethylene, polybutyl acrylate, polyacrylonitrile, etc.; in the exemplary examples, the water-soluble binder can include one or more of carboxymethyl cellulose, carboxymethyl cellulose salts, polyacrylic acid, polyacrylic acid salts, polyvinyl alcohol, sodium alginate, cyclodextrin, etc.; in the exemplary examples, the emulsion binder includes one or more of styrene-butadiene rubber, vinyl acetate resin, acrylic resin, chlorinated rubber.

[0146] This range of content and the above types of binders can effectively enhance the mechanical properties of the cathode active material layer and the bonding strength with the current collector, and can effectively improve the cycling performance of the cathode.

[0147] In an embodiment, the mass content of the conductive agent contained in the above-mentioned positive electrode active material layer may be 0.5% to 5%, optionally 1% to 3%. In an exemplary embodiment, it may be 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3% and other typical but non-limiting contents or the range between any two content values. In an embodiment, the conductive agent may include one or more of acetylene black (SP), conductive carbon black (super-P), Ketjen black, graphene, etc. The range of the content and the above-mentioned types of conductive agents can effectively improve the conductivity of the positive electrode active material layer.

[0148] Negative electrode sheet of the electrode assembly:

[0149] In an embodiment, the negative electrode sheet contained in the electrode assembly may include a negative electrode current collector, and may also optionally include a negative electrode active material layer provided on at least one surface of the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material. In an embodiment, the negative electrode current collector may include, but is not limited to, a metal or a composite current collector. For example, as the metal, sodium, sodium alloy, lithium, lithium alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. may be used. When sodium or sodium alloy is used as the negative electrode current collector, since sodium or sodium alloy itself can also be used as the negative electrode active material; similarly, when lithium or lithium alloy is used as the negative electrode current collector, since lithium or lithium alloy itself can also be used as the negative electrode active material; therefore, the negative electrode sheet may not contain a negative electrode active material layer, and sodium, sodium alloy or lithium, lithium alloy is both a current collector and a negative electrode active material.

[0150] The composite current collector may include a composite material of a polymer material and a metal. The polymer material therein may include, but is not limited to, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc., and the metal may include, but is not limited to, sodium, lithium, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy. The composite current collector may be obtained by mixing the polymer material and the metal with each other, or may be coated on at least one side of the polymer material by electroplating, coating or other means.

[0151] When the negative electrode includes a negative electrode active material layer, the negative electrode active material in the negative electrode active material layer may include, but is not limited to, any one or more of carbon-based materials, alloy materials, titanium-based materials, sodium metal, lithium metal to form a mixed or composite material. Among them, the carbon-based materials include, but are not limited to, one or more of graphite, soft carbon, hard carbon, carbon microspheres, carbon fibers; the alloy materials include, but are not limited to, one or more of sodium tin alloy, sodium germanium alloy, sodium antimony alloy, or the alloy materials include, but are not limited to, one or more of lithium tin alloy, lithium germanium alloy, lithium antimony alloy; the titanium-based materials include, but are not limited to, one or more of titanium dioxide, titanate, titanium phosphate.

[0152] The mass content of the negative electrode active material in the negative electrode active material layer can be 85% - 98%, preferably 95% - 98%. In exemplary embodiments, typical but non-limiting contents such as 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or the range between any two content values can be used.

[0153] The negative electrode active material layer may further include at least one of a conductive agent and a binder. The conductive agent is used to collect current between the negative electrode active materials and between the active material and the current collector, improving the electronic conductivity. At the same time, the conductive agent can also promote the infiltration of the electrolyte into the negative electrode sheet. The binder can improve the bonding strength between the substances in the negative electrode active material layer and between the negative electrode active material layer and the current collector.

[0154] In an embodiment, the mass content of the conductive agent in the negative electrode active material layer can be 0.5% - 10%. In exemplary embodiments, typical but non-limiting contents such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the range between any two content values can be used, and it can also be set to other contents according to needs. In exemplary embodiments, the conductive agent includes one or more of acetylene black (SP), carbon nanotubes, conductive carbon black (super-P), Ketjen black, carbon fiber, and graphene.

[0155] In an embodiment, the mass content of the binder in the negative electrode active material layer can be 0.5% - 10%. In exemplary embodiments, typical but non-limiting contents such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the range between any two content values can be used, and it can also be set to other contents according to needs. In exemplary embodiments, the binder includes, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene copolymer, polyethylene oxide, polyimide, polytetrafluoroethylene, butyl acrylate, polyacrylonitrile, carboxymethyl cellulose, carboxymethyl cellulose salt, polyacrylic acid, polyacrylate, polyvinyl alcohol, sodium alginate, cyclodextrin, styrene-butadiene rubber, vinyl acetate resin, acrylic resin, and chlorinated rubber.

[0156] In an embodiment, the negative electrode active material layer may optionally further include a thickening agent, such as, but not limited to, carboxymethyl cellulose (CMC). The mass content of the thickening agent in the negative electrode active material layer can be set to 0.5% - 5%. In exemplary embodiments, typical but non-limiting contents such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or the range between any two content values can be used.

[0157] Separator of the electrode assembly:

[0158] In the embodiment, the separator membrane, as described above, is disposed between the positive electrode plate and the negative electrode plate to separate the positive electrode plate and the negative electrode plate. The separator membrane can prevent electrons in the battery cell from freely passing through, preventing short circuit due to contact between the electrodes, but can allow cations such as sodium ions or lithium ions in the electrolyte to freely pass between the positive electrode plate and the negative electrode plate. The separator membrane can be any well-known porous structure separator membrane with electrochemical stability and mechanical stability. In the embodiment, the separator membrane includes at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF) in the form of a single-layer or multi-layer film.

[0159] Battery module:

[0160] The battery module is assembled from battery cells, that is, it can contain multiple above-mentioned battery cells, and the specific number can be adjusted according to the application and capacity of the battery module.

[0161] The battery module of this application embodiment contains the battery cells of the above application embodiment. Therefore, the battery module of this application embodiment has the electrochemical performance of the above battery cells, has a low DCR, and its DCR stability is good, improving the RTE of the battery module during service, and also improving the cycle performance of the battery module.

[0162] In some embodiments, Figure 3 is a schematic diagram of a battery module 20 as an example. As Figure 3 shown, in the battery module 20, multiple battery cells 10 can be arranged in sequence along the length direction of the battery module 20. Of course, they can also be arranged in any other way. Further, the multiple battery cells 10 can be fixed by fasteners.

[0163] Optionally, the battery module 20 can further include a housing with an accommodation space, and multiple battery cells 10 are accommodated in the accommodation space.

[0164] Battery pack:

[0165] The battery pack is assembled from the battery cells of the above application embodiment of this application, that is, it can contain multiple battery cells of the above application embodiment of this application, and multiple such battery cells are assembled into the above battery module. The specific number of the battery cells or the battery module contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0166] Since the battery of this application embodiment contains the battery cells of the above application embodiment of this application, therefore, the battery pack of this application embodiment has the electrochemical performance of the above battery cells, has a low DCR, and its DCR stability is good, improving the RTE of the battery pack during service, and also improving the cycle performance of the battery pack.

[0167] In some embodiments,Figure 4 It is a schematic diagram of a battery pack 30 as an example. The battery pack 30 may include a battery box and a plurality of battery modules 20 disposed in the battery box. The battery box includes an upper box body 31 and a lower box body 32. The upper box body 31 is used to cover the lower box body 32 and form a closed space for accommodating the battery modules 20. The plurality of battery modules 20 can be arranged in the battery box in any manner.

[0168] [Power-consuming device]

[0169] In a fourth aspect, an embodiment of the present application further provides a power-consuming device. The power-consuming device in the embodiment of the present application includes a power supply unit or an energy storage unit, and of course, other auxiliary components or necessary components may also be included. Among them, the power supply unit or the energy storage unit contains the battery in the above embodiment of the present application. For example, it may be a battery cell, a battery module or a battery pack in the above embodiment of the present application. Since the power-consuming device in the embodiment of the present application contains the battery cell, the battery module or the battery pack in the above embodiment of the present application, therefore, the RTE of the power supply unit or the energy storage unit of the power-consuming device in the embodiment of the present application is high, the cycle performance is good, the service life is long, and the standby or endurance time of the power-consuming device in the embodiment of the present application is long.

[0170] In the embodiment, the power-consuming device may include, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, etc. As the power-consuming device, the battery cell, the battery module or the battery pack in the battery can be selected according to its usage requirements.

[0171] Figure 5 It is a schematic diagram of a power-consuming device as an example. The power-consuming device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the power-consuming device for high power and high energy density, a battery pack or a battery module can be used.

[0172] In the embodiment, when the power-consuming device includes an energy storage unit, the power-consuming device can be an energy storage device. The energy storage device includes an energy storage unit, and of course, other auxiliary components or necessary components may also be included. Among them, the energy storage unit contains the battery in the above embodiment of the present application. The battery contained in the energy storage unit can be one or more. When there are multiple batteries, the multiple batteries can form a battery module or a battery pack. Since the energy storage device in the embodiment of the present application contains the battery in the above embodiment of the present application, therefore, the energy storage device has a high energy density, good cycle performance, a long service life, and a further high energy density.

[0173] [Embodiment]

[0174] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation of the present application. For those technologies or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0175] 1. Electrolyte Embodiments

[0176] Embodiments A1 to A36:

[0177] Embodiments A1 to A36 of the present application each provide an electrolyte. Each electrolyte includes an anhydrous organic solvent and a lithium salt and an additive composition dissolved in the anhydrous organic solvent. Among them, the anhydrous organic solvent includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), and the mass ratio of EC:EMC:DEC is 3:5:2; the lithium salt contains lithium hexafluorophosphate (LiPF 6 ), and its molar concentration in the electrolyte is 1.0 mol / L. The anhydrous organic solvent and the lithium salt constitute a basic electrolyte. The types and contents of the components contained in the additive composition dissolved in the basic electrolyte are shown in Table 1 below.

[0178] The preparation methods of the electrolytes in Embodiments A1 to A36: In a glove box filled with argon (moisture < 5 ppm, oxygen content < 10 ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are uniformly mixed according to the mass ratio of EC:EMC:DEC = 3:5:2. Lithium hexafluorophosphate (LiPF 6 ) is slowly added to the mixed solution until the molar concentration of LiPF 6 is 1.0 mol / L to obtain a basic electrolyte. According to the types and contents of the additive compositions contained in Embodiments A1 to A36 in Table 1 below, the corresponding types and amounts of additives are respectively added to the basic electrolyte to prepare the electrolytes of Embodiments A1 to A36.

[0179] Comparative Examples A1 to A3:

[0180] Comparative Examples A1 to A3 of the present application each provide an electrolyte. Each electrolyte includes an anhydrous organic solvent and a lithium salt and an additive dissolved in the anhydrous organic solvent. The difference between the electrolytes in Comparative Examples A1 to A3 and the electrolyte in Embodiment A1 lies in that the types and contents of the additives contained in the electrolytes in Comparative Examples A1 to A3 are different, as shown in the additives contained in Comparative Examples A1 to A3 in Table 1 below.

[0181] The preparation methods of the electrolytes in Comparative Examples A1 to A3 are the same as those of the electrolytes in Example A1, except that the additives contained in Comparative Examples A1 to A3 are added according to the additives in Comparative Examples A1 to A3 in Table 1 below.

[0182] Table 1

[0183]

[0184]

[0185] The acidity of the electrolytes in the above Examples A1 to A36 and Comparative Examples A1 to A3 was detected respectively according to the following method:

[0186] Take 20 g of each electrolyte in Examples A1 to A36 and Comparative Examples A1 to A3 respectively in a conical flask, weigh and record as mass m, add 1 - 2 drops of neutral red methylene blue mixed indicator, titrate with triethylamine ultra-dry acetonitrile solution with a concentration of c, record the titration volume V of the standard solution, and calculate the acidity of the electrolyte according to the following formula:

[0187] Electrolyte acidity (ppm) = 20.006 * 1000 * V * c / m

[0188] The electrolytes in the remaining examples were filled into dried aluminum-plastic bottles, sealed and then placed in an oven at 60 °C for three days. Then the electrolytes were taken out and the acidity of the electrolytes was measured again according to the above method. The test results are distributed as shown in Table 2 below. Among them, the acidity difference in Table 2 is the difference between the acidity value of the electrolyte after being placed at 60 °C for 3 days and the initial acidity.

[0189] Table 2

[0190] Example Initial acidity Acidity after standing at 60°C for 3 days Acidity difference Example A1 9.4 26.7 17.3 Example A2 9.5 21.6 12.1 Example A3 9.6 22.4 12.8 Example A4 9.6 21.3 11.7 Example A5 9.5 21.0 11.5 Example A6 9.5 21.9 12.4 Example A7 9.6 22.3 12.7 Example A8 9.4 22.1 12.7 Example A9 9.5 21.8 12.3 Example A10 9.5 22.5 13 Example A11 9.4 22.1 12.7 Example A12 9.6 21.9 12.3 Example A13 9.3 20 10.7 Example A14 9 19.1 10.1 Example A15 9.1 18.9 9.8 Example A16 8.9 17.6 8.7 Example A17 9.4 23.4 14 Example A18 9.5 23.6 14.1 Example A19 9.5 22.9 13.4 Example A20 9.6 23.5 13.9 Example A21 9.7 24.1 14.4 Example A22 9.6 24.2 14.6 Example A23 9.5 25.3 15.8 Example A24 9.6 24.8 15.2 Example A25 9.5 24.9 15.4 Example A26 9.5 25.7 16.2 Example A27 9.4 18.2 8.8 Example A28 9.2 19 9.8 Example A29 9.4 19.1 9.7 Example A30 9.1 18.6 9.5 Example A31 9.4 18.8 9.4 Example A32 9.4 21.5 12.1 Example A33 9.4 22.8 13.4 Example A34 9.4 23.4 14 Example A35 9.4 27.7 18.3 Example A36 9.5 20.3 10.8 Comparative Example A1 10.9 49.4 38.5 Comparative Example A2 9.8 40.3 30.5 Comparative Example A3 9.5 18.5 9

[0191] 2. Battery cell examples

[0192] Examples B1 to B36:

[0193] Examples B1 to B36 respectively provide a lithium-ion battery cell. The lithium-ion battery cells in Examples B1 to B36 include an outer package and an electrode assembly encapsulated in the outer package. The electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked, and the separator is stacked between the positive electrode sheet and the negative electrode sheet, and the electrode assembly is immersed in the electrolyte. Among them, the electrolyte of the lithium-ion battery cell in Example B1 is the electrolyte in Example A1, the electrolyte of the lithium-ion battery cell in Example B2 is the electrolyte in Example A2, and so on. The electrolyte of the lithium-ion battery cell in Example B36 is the electrolyte in Example A36.

[0194] The lithium-ion battery cells in Examples B1 to B36 were assembled according to the following method:

[0195] Positive electrode sheet: Lithium iron phosphate (LiFePO 4 ) as the lithium-ion positive electrode active material, carbon black as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder were fully stirred and mixed in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a weight ratio of 97:1:2 to prepare a positive electrode active paste with a solid content of 63 wt% and a viscosity of 16000 mPa·s. Then, the positive electrode active paste was coated on a 13-μm aluminum foil through a double-sided coating device, dried, further dried, cold-pressed (2.4 g / cc, thickness of 200 μm), and slit to obtain the positive electrode sheet;

[0196] Negative electrode sheet: Artificial graphite as the negative electrode active material, conductive carbon black as the conductive agent, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC) as the thickener were mixed at a mass ratio of 95:1:2:2, added with deionized water and stirred, and dispersed to prepare a negative electrode active paste with a solid content of 55% and a viscosity of 7000 mPa·s. Then, the negative electrode active paste was coated on a copper foil (thickness of 6 μm) by using a double-sided coating device, and then dried, cold-pressed (coating density of 1.6 g / cc, thickness of 160 μm), and slit to obtain the original negative electrode sheet;

[0197] Electrolyte: The electrolytes in Examples A1 to A36 and Comparative Examples A1 to A3 were used as the electrolytes for the lithium-ion battery cells respectively;

[0198] Separator: A 12-μm thick porous polyethylene (PE) separator was selected.

[0199] Battery assembly: The above positive electrode sheets, separators, and negative electrode sheets were stacked in sequence, with the separator placed in the middle between the positive electrode sheet and the negative electrode sheet to play a separating role, and an electrode assembly was obtained through the stacking process. Each electrode assembly was placed in an outer package, dried, injected with electrolyte, and then subjected to processes such as vacuum packaging, standing, forming, and shaping to obtain the lithium-ion battery cell. Among them, the electrolyte in Example A1 was used as the electrolyte for the lithium-ion battery cell in Example B1, the electrolyte in Example A2 was used as the electrolyte for the lithium-ion battery cell in Example B2, and so on, and the electrolyte in Example A36 was used as the electrolyte for the lithium-ion battery cell in Example B36.

[0200] Comparative Examples B1 to B3:

[0201] Comparative Examples B1 to B3 each provide a lithium-ion battery cell. Compared with the lithium-ion battery cell in Example B1, the difference in the lithium-ion battery cells of Comparative Examples B1 to B3 lies in the different electrolytes. Specifically, the electrolyte of the lithium-ion battery cell in Comparative Example B1 is the electrolyte in Comparative Example A1, the electrolyte of the lithium-ion battery cell in Comparative Example B2 is the electrolyte in Comparative Example A2, and so on. The electrolyte of the lithium-ion battery cell in Comparative Example B3 is the electrolyte in Comparative Example A3.

[0202] The lithium-ion battery cells in Comparative Examples B1 to B3 are assembled by referring to the method of the lithium-ion battery cell in Example B1.

[0203] Electrochemical performance test of lithium-ion battery cells:

[0204] The lithium-ion battery cells provided in the above Examples B1 to B36 and Comparative Examples B1 to B3 are respectively subjected to the relevant electrochemical performance tests in Table 3 below according to the following method, and the test results are shown in Table 3. Among them, the method for detecting the relevant electrochemical performance of the lithium-ion battery cells in Table 3 is as follows:

[0205] The test method for direct current internal resistance (DCR) is as follows:

[0206] (1) At 25 °C, charge at a constant current of 1 / 3C to 3.65V, then charge at a constant voltage until the current is less than 0.05C, and let it stand for 5 min;

[0207] (2) Discharge at a constant current of 1C for timing, and adjust the state of charge (SOC) of the battery to 90% SOC, 50% SOC, and 20% SOC respectively;

[0208] (3) Conduct tests of 1C DC 30s and 1C CC 30s at the three SOCs respectively;

[0209] (4) Calculate the direct current internal resistance DCR of 1C CC 30s;

[0210] The test method for energy conversion efficiency (RTE) is as follows:

[0211] (1) Charging: At 25 °C, charge at a constant power of 1P to 3.65V, and let it stand for 5 min;

[0212] (2) Discharging: At 25 °C, discharge at a constant power of 1P to 2.5V, and let it stand for 5 min;

[0213] (3) Repeat the charge and discharge three times;

[0214] (4) Calculate RTE = discharge energy / charging energy, and take the average value of the three numerical values as the RTE of the battery.

[0215] Table 3

[0216]

[0217]

[0218] Based on the electrolyte acidity data in Table 3 and the acidity data in Table 2 above, by comparing Examples A1 / B1 to Examples A2 / B2, Example A7 / B7, and Examples A13 / B13 to A16 / B16, it can be seen that on the premise that the content of the impedance stabilizer in the electrolyte remains the same, appropriately increasing the amount of isocyanate additives can reduce the acidity of the electrolyte and improve the stability of the electrolyte acidity; the DCR of the corresponding battery cells is stable. Among them, when the content of isocyanate additives is appropriately increased, such as when the weight ratio of PI:MMDS increases from 0.1:1 to 0.25:1, the energy conversion efficiency (RTE) and cycle performance of the battery cells are correspondingly improved; when the content of isocyanate additives continues to increase, such as when the weight ratio of PI:MMDS increases from 0.3:1 to 0.8:1, the energy conversion efficiency (RTE) and cycle performance of the battery cells decrease.

[0219] By comparing Example A1 / B1 with Comparative Examples A1 / B1 to A2 / B2, it can be seen that when the content of isocyanate additives in the electrolyte is too low, such as as low as 0.18 wt%, it causes a significant increase in the acidity of the electrolyte; the DCR of the corresponding battery cells also increases, and its stability decreases; moreover, the energy conversion efficiency (RTE) and cycle performance decrease significantly.

[0220] By comparing Example A16 / B16 with Comparative Example A3 / B3, it can be seen that when the content of isocyanate additives in the electrolyte increases up to a weight ratio of PI:MMDS of 0.9:1, although the acidity of the electrolyte does not increase significantly, the DCR, energy conversion efficiency (RTE), and cycle performance of the corresponding battery cells all decrease significantly.

[0221] By comparing Examples A3 / B3 to A9 / B9, it can be seen that on the premise that the content of the impedance stabilizer and isocyanate additives remains the same, appropriately increasing the content of inorganic carbonate does not cause a significant change in the acidity of the electrolyte, indicating that the electrolyte maintains good stability; the DCR of the corresponding battery cells also does not change significantly. Therefore, the DCR of the battery cells maintains good stability. Among them, when the inorganic carbonate increases from 0 wt% to 0.5 wt%, the energy conversion efficiency (RTE) and cycle performance of the battery cells are correspondingly improved.

[0222] Comparing Comparative Examples A13 / B13, Examples A19 / B19, A22 / B22 to A26 / B26, it can be seen that on the premise that the contents of the impedance stabilizer and the isocyanate additives remain the same, by changing the types of the isocyanate additives in the order of DOPI, TMPI, TFPI, FPI, HDI, PTSI, PI, the acidity stability of the electrolyte is enhanced in turn by these isocyanate additives, and the energy conversion efficiency (RTE) and cycle performance of the corresponding battery cells are also improved in turn.

[0223] Comparing Comparative Examples A15 / B15, Examples A27 / B27 to A31 / B31, it can be seen that on the premise that the content of the impedance stabilizer remains the same, when two or more isocyanate additives are compounded, the compounded isocyanate additives can significantly improve the stability of the acidity value of the electrolyte, and the energy conversion efficiency (RTE) and cycle performance of the corresponding battery cells are also significantly improved. This shows that there is a synergistic effect among these compounded isocyanate additives, which can improve the stability of the electrolyte and the energy conversion efficiency (RTE) and cycle performance of the battery cells.

[0224] Comparing Comparative Examples A13 / B13, Examples A32 / B32 to A35 / B35, it can be seen that on the premise that the content ratio of the isocyanate additive to the impedance stabilizer remains the same, adjusting the content of the impedance stabilizing additive has a certain influence on the acidity value, energy conversion efficiency (RTE) and cycle performance of the electrolyte. When the content of the impedance stabilizer is 2 wt% in Comparative Example A13 / B13, it can relatively significantly improve the acidity value stability of the electrolyte and the energy conversion efficiency (RTE) and cycle performance of the battery cell.

[0225] Comparing Comparative Example A13 / B13 with Example A36 / B36, it can be seen that on the premise that the content ratio of the isocyanate additive to the impedance stabilizer remains the same, when changing the type of the impedance stabilizing additive, the stability of the acidity of the electrolyte can be effectively maintained. At the same time, the energy conversion efficiency (RTE) and cycle performance are also significantly improved compared with the battery cells of Comparative Examples A1 / B1 to A3 / B3. Among them, compared with DTD, MMDS can relatively significantly improve the energy conversion efficiency (RTE) of the battery cell.

[0226] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrolyte additive composition, characterized in that: It comprises an impedance stabilizing additive and an isocyanate additive, wherein the weight ratio of the isocyanate additive to the impedance stabilizing additive is 0.1-0.8:

1.

2. The electrolyte additive composition according to claim 1, characterized in that: The weight ratio of the isocyanate additive to the impedance stabilizer additive is 0.2-0.5:

1.

3. The electrolyte additive composition according to claim 1 or 2, characterized in that: The isocyanate additive includes at least one of phenyl isocyanate, p-toluenesulfonyl isocyanate, hexamethylene diisocyanate, 4-fluorophenyl isocyanate, 2,4,6-trifluorophenyl isocyanate, 2,4,6-trimethoxy isocyanate, and diethoxyphosphino isocyanate.

4. The electrolyte additive composition according to any one of claims 1 to 3, characterized in that: The isocyanate additive comprises at least one isocyanate additive composition selected from the group consisting of (1) to (5): (1) A mixture comprising phenyl isocyanate and p-toluenesulfonyl isocyanate; (2) A mixture comprising phenyl isocyanate and hexamethylene diisocyanate; (3) A mixture comprising phenyl isocyanate and 2,4,6-trimethoxyisocyanate; (4) A mixture comprising hexamethylene diisocyanate and p-toluenesulfonyl isocyanate; (5) Any one of a mixture comprising 4-fluorophenyl isocyanate and p-toluenesulfonyl isocyanate.

5. The electrolyte additive composition according to any one of claims 1 to 4, characterized in that: The impedance stabilizing additive comprises at least one of methylene methane disulfonate and vinyl sulfate; and / or Also included are organic film-forming additives.

6. The electrolyte additive composition according to claim 5, characterized in that: The weight ratio of the organic film-forming additive to the impedance stabilizing additive is (2-10): (0.5-5), optionally (3-7): (0.5-5); and / or The organic film-forming additive includes an alkenyl ester additive.

7. The electrolyte additive composition according to claim 6, characterized in that: The alkenyl ester-containing additive includes at least one of vinylene carbonate, fluoroethylene carbonate, vinyl vinyl carbonate, and methylene vinyl carbonate.

8. The electrolyte additive composition according to any one of claims 1 to 7, characterized in that: The electrolyte additive composition also includes an inorganic carbonate.

9. The electrolyte additive composition according to claim 8, characterized in that The weight ratio of the inorganic carbonate to the impedance stabilizing additive is (0.01-1):(0.5-5), optionally (0.05-0.5):(0.5-5); and / or The inorganic carbonates include alkali metal carbonates.

10. An electrolyte comprising an organic solvent and an electrolyte dissolved in the organic solvent, characterized in that: The electrolyte additive composition according to any one of claims 1 to 9 is mixed in the organic solvent.

11. The electrolyte according to claim 10, characterized in that The content of the electrolyte additive composition in the electrolyte satisfies: The concentration of the impedance stabilizing additive in the electrolyte is 0.5 wt % to 5 wt %, and optionally 1 wt % to 3 wt %.

12. The electrolyte according to claim 10 or 11, characterized in that: The organic solvent includes at least one of cyclic carbonate, chain carbonate, cyclic ether, chain ether and sulfone compound.

13. The electrolyte according to claim 12, characterized in that: The cyclic carbonate comprises at least one of ethylene carbonate, propylene carbonate, butylene carbonate and γ-butyrolactone; and / or The linear carbonate comprises at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl formate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate; and / or The cyclic ether includes at least one of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane and 4-methyl-1,3-dioxolane; and / or The chain ether includes at least one of dimethoxymethane, 1,2-dimethoxyethane, 1,2-dimethoxypropane and diethylene glycol dimethyl ether.

14. The electrolyte according to any one of claims 10 to 13, characterized in that: The electrolyte comprises at least one of a lithium salt and a sodium salt; and / or The concentration of the electrolyte in the electrolyte solution is 7 wt % to 13 wt %, and optionally 8 wt % to 11 wt %.

15. A battery, characterized in that: The electrolyte comprising the electrolyte according to any one of claims 10 to 14.

16. An electrical device, characterized in that: Comprising the battery as claimed in claim 15.

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