Electrolyte, battery and electric equipment

Abstract

The invention provides an electrolyte, a battery and electric equipment, the electrolyte comprises a redox mediator pair, the redox mediator pair only has one oxidation potential, and the oxidation potential of the redox mediator pair is 3.4-4.2 V. As a result, the decomposition voltage of the capacity compensator is reduced, and the cycle capacity retention ratio of the battery is improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular, to electrolytes, batteries and electrical equipment. Background Art

[0002] Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. During the formation process of the battery, a solid electrolyte membrane (SEI membrane) will be formed. The formation of the SEI membrane will consume active ions. In order to compensate for the irreversible capacity loss caused by the formation of the SEI membrane, a capacity compensation material is set on the positive electrode at the same time. During the first week of charging, the capacity compensation material can release enough active ions to improve the first efficiency of the battery. However, the decomposition voltage of the capacity compensator is relatively high, which reduces the capacity compensation effect and reduces the cycle capacity retention rate of the battery. Summary of the invention

[0003] In view of the technical problems existing in the background technology, the present application provides an electrolyte that can reduce the decomposition voltage of the capacity compensating agent, improve the effect of capacity compensation, and improve the cycle capacity retention rate of the battery.

[0004] A first aspect of the present application provides an electrolyte comprising a redox pair, wherein the redox pair has only one oxidation potential, and the oxidation potential of the redox pair is 3.4V-4.2V.

[0005] The electrolyte proposed in the present application, the redox pair in the electrolyte can catalyze the capacity compensator to decompose active ions to compensate for the capacity loss caused by the formation of the SEI film. The redox pair in the electrolyte and the capacity compensator are in solid-liquid contact, which can improve the contact efficiency between the redox pair and the capacity compensator. Since the redox pair has only one oxidation potential, it is a single-electron reaction in the process of catalyzing the capacity compensator, which can improve the catalytic efficiency of the redox pair and reduce the decomposition voltage of the capacity compensator. By making the oxidation potential of the redox pair within the above range, the oxidation potential of the redox pair can be reduced, the catalytic efficiency of the redox pair can be further improved, the decomposition voltage of the capacity compensator can be reduced, the effect of capacity compensation can be improved, and the cycle capacity retention rate of the battery can be improved.

[0006] According to some embodiments of the present application, the oxidation potential of the redox pair is 3.5 V-4 V. Thus, the oxidation potential of the redox pair is reduced, the catalytic efficiency of the redox pair is improved, the decomposition voltage of the capacity compensator is reduced, the effect of capacity compensation is improved, and the cycle capacity retention rate of the battery is improved.

[0007] According to some embodiments of the present application, the molar concentration of the redox pair is 1 mmol / L-100 mmol / L.

[0008] According to some embodiments of the present application, the molar concentration of the redox mediator is 5 mmol / L-50 mmol / L.

[0009] According to some embodiments of the present application, the molar concentration of the redox pair is 10 mmol / L-20 mmol / L.

[0010] Therefore, by setting the content of the redox pair within the above range, the catalytic efficiency of the redox pair is improved, the viscosity of the electrolyte is reduced, and the conductivity of the electrolyte is improved.

[0011] According to some embodiments of the present application, the redox mediator includes at least one of an aromatic nitroxide free radical organic compound or a metal organic coordination compound. Thus, the redox mediator of the above type has only one oxidation potential, which can improve its catalytic efficiency, reduce the decomposition voltage of the capacity compensator, and improve the cycle capacity retention rate of the battery.

[0012] According to some embodiments of the present application, the metal organic coordination compound includes metal ions and organic ligand ions, the metal ions include at least one of cobalt ions, zinc ions, copper ions, iron ions, nickel ions, manganese ions or ruthenium ions, and the organic ligand includes at least one of a phthalocyanine group, a terpyridine group, a cyclopentadiene group, a polypyridine group or a porphyrin group. Thus, the formed metal organic coordination compound has only one oxidation potential, which can improve its catalytic efficiency, reduce the decomposition voltage of the capacity compensator, and improve the cycle capacity retention rate of the battery.

[0013] According to some embodiments of the present application, the aromatic nitrogen oxide free radical organic matter includes at least one of 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 2-azaadamantane-N-oxyl free radical, 1-methyl-2-azaadamantane-N-oxyl free radical, 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide or tert-pentyl-tert-butylnitroxide. Thus, the above-mentioned types of aromatic nitrogen oxide free radical organic matter have only one oxidation potential, which can improve its catalytic efficiency, reduce the decomposition voltage of the capacity compensator, and improve the cycle capacity retention rate of the battery.

[0014] According to some embodiments of the present application, the metal organic coordination compound includes at least one of tetraphenylporphyrin iron, tetraphenylporphyrin nickel, tetraphenylporphyrin cobalt, tetraphenylporphyrin manganese, tetraphenylporphyrin zinc, phthalocyanine iron, phthalocyanine cobalt, phthalocyanine nickel, bis(terpyridine) cobalt, bis(terpyridine) iron, bis(terpyridine) manganese, ferrocene, bis(terpyridine) nickel, bis(cobalt) zinc, or bis(terpyridine) ruthenium. Thus, the above-mentioned metal organic coordination compound has only one oxidation potential, which can improve its catalytic efficiency, reduce the decomposition voltage of the capacity compensator, and improve the cycle capacity retention rate of the battery.

[0015] According to some embodiments of the present application, the electrolyte further includes an additive, wherein the additive includes X ions, and the X ions can be combined with active ions to form a solid electrolyte membrane. Thus, the damage to the SEI caused by the oxidation state substances formed by the redox medium shuttling between the positive and negative electrodes is reduced, and the SEI membrane is protected.

[0016] According to some embodiments of the present application, the X ions include at least one of fluoride ions or nitrogen ions. Thus, the fluoride ions or nitrogen ions can form fluoride or nitride with active ions at the negative electrode to protect the SEI film.

[0017] According to some embodiments of the present application, the additive includes at least one of a fluorine-containing amide additive or a nitrogen-containing amide additive. Thus, the above-mentioned type of additive can form fluoride or nitride with active ions at the negative electrode to protect the SEI film.

[0018] According to some embodiments of the present application, the fluorine-containing amide additive includes at least one of N,N-dimethyl trifluoroacetamide, N,N-diethyl trifluoroacetamide, bis trifluoroacetamide, N-benzyl trifluoroacetamide, 4-N,N-dimethylamino trifluoroacetophenone or bis (trimethylsilyl) trifluoroacetamide. Thus, the above-mentioned types of fluorine-containing amide additives can decompose fluoride ions, which can form fluoride at the negative electrode to protect the SEI film.

[0019] According to some embodiments of the present application, the nitrogen-containing amide additive includes at least one of 2-amino-N,N-dimethylacetamide, 2-(4-aminophenyl)-N,N-dimethylacetamide or 2-(4-aminopiperidin-1-yl)-N,N-dimethylacetamide. Thus, the above-mentioned nitrogen-containing amide additives can decompose nitrogen ions, and fluoride ions can form fluoride at the negative electrode to protect the SEI film.

[0020] According to some embodiments of the present application, the ratio of the molar concentration of the redox pair to the molar concentration of the additive is 100:(10-40). Thus, while improving the catalytic efficiency of the redox pair, the damage to the SEI film caused by the oxidized substances of the redox pair shuttling between the positive and negative electrodes is reduced.

[0021] According to some embodiments of the present application, the ratio of the molar concentration of the redox pair to the molar concentration of the additive is 100:(15-25). Thus, while improving the catalytic efficiency of the redox pair, the damage to the SEI film caused by the oxidized substances of the redox pair shuttling between the positive and negative electrodes is reduced.

[0022] According to some embodiments of the present application, the molar concentration of the additive is 0.1 mmol / L-40 mmol / L, thereby reducing the damage to the SEI film caused by the oxidized substances of the redox medium shuttling between the positive and negative electrodes.

[0023] According to some embodiments of the present application, the molar concentration of the additive is 0.75 mmol / L-12.5 mmol / L, thereby reducing the damage to the SEI film caused by the oxidized substances of the redox medium shuttling between the positive and negative electrodes.

[0024] The second aspect of the present application provides a battery, comprising the electrolyte provided in the first aspect of the present application, thereby improving the cycle capacity retention rate of the battery.

[0025] According to some embodiments of the present application, the battery includes a positive electrode sheet, the positive electrode sheet includes a positive current collector, at least one side of the positive current collector is provided with a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material and a capacity compensator. Thus, the redox medium in the electrolyte can catalyze the decomposition of the capacity compensator to compensate for the capacity, thereby improving the cycle capacity retention rate of the battery.

[0026] According to some embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensating agent is 0.5%-20%, thereby improving the effect of capacity compensation and improving the cycle capacity retention rate of the battery.

[0027] According to some embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensating agent is 1%-10%, thereby improving the effect of capacity compensation and the cycle capacity retention rate of the battery.

[0028] According to some embodiments of the present application, the volume average particle size D of the capacity compensating agent is v 50 is 0.05 μm-30 μm. Thus, the decomposition difficulty of the capacity compensating agent is reduced, the utilization rate of the capacity compensating agent is improved, and the cycle capacity retention rate of the battery is improved.

[0029] According to some embodiments of the present application, the volume average particle size D of the capacity compensating agent is v 50 is 0.05 μm-15 μm. Thus, the decomposition difficulty of the capacity compensating agent is reduced, the utilization rate of the capacity compensating agent is improved, and the cycle capacity retention rate of the battery is improved.

[0030] According to some embodiments of the present application, the capacity compensating agent includes a lithium supplement and / or a sodium supplement, wherein the lithium supplement includes at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF; and the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF. Thus, the capacity loss caused by the formation of the SEI film is compensated and the energy density of the battery is improved.

[0031] The third aspect of the present application provides an electrical device, including the battery provided in the second aspect of the present application.

[0032] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0034] Figure 1 is a schematic diagram of a battery according to one embodiment of the present application.

[0035] Figure 2 yes Figure 1 An exploded view of a battery according to an embodiment of the present application is shown.

[0036] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0037] Figure 4 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0038] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0039] Figure 6 It is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0042] The following is a detailed description of the embodiments of the technical solution of the present application. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0046] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0047] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0048] At present, from the perspective of market development, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of battery application areas, its market demand is also constantly expanding.

[0049] During the formation process of the battery, a SEI film will form on the surface of the negative electrode. A large amount of active ions will be consumed during the formation of the SEI film, which will reduce the initial efficiency of the battery. In order to improve the initial efficiency of the battery, the positive electrode can be pre-capacity compensated. When performing capacity compensation on the positive electrode, a capacity compensator rich in active ions is usually used to establish a capacity compensation layer on the positive electrode plate. Sufficient active ions are released during the first week of charge and discharge to compensate for the irreversible capacity loss caused by the formation of the SEI film. Usually, the decomposition voltage of the capacity compensator is relatively high, and a redox mediator needs to be added to the electrolyte to catalyze the decomposition of the capacity compensator to reduce the decomposition voltage of the capacity compensator. However, the redox mediator X in the related art catalyzes the capacity compensator in a two-electron reaction. Specifically, X catalyzes the capacity compensator in two steps: the first step is that at a low potential, X - First oxidized to X n - Although the oxidation potential of this process is low, X n - The efficiency of catalytic capacity compensator decomposition is low; in the second step, X n - Oxidized to X at high potential n (2≤n≤3), X n The efficiency of catalytic capacity compensator decomposition is high, but the oxidation potential of this process is high. Moreover, at high potential, X n - Oxidized to X n and X n - The decomposition of the catalytic capacity compensator will proceed simultaneously, n - Oxidized to Xn The reaction compared to X n - Catalytic capacity compensator is more likely to occur and will inhibit X - The catalytic decomposition of the capacity compensating agent causes most of the capacity compensating agent to be decomposed at a higher potential, thereby reducing the utilization rate of the capacity compensating agent and reducing the capacity compensation effect.

[0050] The electrolyte proposed in the present application has a redox pair in the electrolyte having only one oxidation potential, and the process of catalyzing the decomposition of the capacity compensator is a single-electron reaction. By making the oxidation potential of the redox pair between 3.4V and 4.2V, the catalytic efficiency of the redox pair can be improved, the decomposition voltage of the capacity compensator can be reduced, the utilization rate of the capacity compensator can be improved, and the cycle capacity retention rate of the battery can be improved.

[0051] The electrolyte disclosed in the embodiments of the present application is suitable for lithium-ion batteries and sodium-ion batteries, and the battery disclosed in the embodiments of the present application can be used in electrical equipment that uses the battery as a power source or various energy storage systems that use the battery as an energy storage element. Electrical equipment may include, but is not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0052] In a first aspect, the present application provides an electrolyte comprising a redox pair, wherein the redox pair has only one oxidation potential, and the oxidation potential of the redox pair is 3.4V-4.2V.

[0053] The electrolyte proposed in the present application, the redox pair in the electrolyte can catalyze the capacity compensator to decompose active ions to compensate for the capacity loss caused by the formation of the SEI film. The redox pair in the electrolyte and the capacity compensator are in solid-liquid contact, which can improve the contact efficiency between the redox pair and the capacity compensator compared to solid-solid contact. Since the redox pair has only one oxidation potential, for example, taking the redox pair as RM and the capacity compensator as Li2C2O4 as an example, the reaction between RM and Li2C2O4 is: 1) RM→RM + +e - 2) 2RM + +Li2C2O4→2Li ++2RM+2CO2, the redox pair proposed in the present application is a single-electron reaction in the process of catalyzing the capacity compensator. After being oxidized, the redox pair can directly catalyze the capacity compensator to decompose active ions, and there is no other competitive reaction, thereby improving the catalytic efficiency of the redox pair and reducing the decomposition voltage of the capacity compensator. By making the oxidation potential of the redox pair within the above range, the oxidation potential of the redox pair can be reduced, the catalytic efficiency of the redox pair can be further improved, the decomposition voltage of the capacity compensator can be reduced, the effect of capacity compensation can be improved, and the cycle capacity retention rate of the battery can be improved.

[0054] In the present application, the active ions may be potassium ions or sodium ions.

[0055] In this application, a redox pair refers to an electrolyte additive. Taking the redox pair as RM as an example, when the capacity compensator is first decomposed, RM can be oxidized to RM + , in the process of catalytic capacity compensator, RM + Can be restored to RM.

[0056] According to some embodiments of the present application, the oxidation potential of the redox pair may be 3.4V, 3.6V, 3.8V, 4V or 4.2V, or may be a range of any of the above values. According to some specific embodiments of the present application, the oxidation potential of the redox pair may be 3.5V-4V.

[0057] The oxidation potential of the redox mediator in this application can be tested by cyclic voltammetry. Specifically, a glassy carbon electrode is used as the working electrode, a platinum electrode is used as the counter electrode, the electrolyte is 0.1M LiPF6 dissolved in EC / EMC solvent, and the electrolyte contains 10mM of the redox mediator. Then, an electrochemical workstation is used to scan a cycle in the 2.5V-4.5V window at a scan rate of 50mV / s, and the peak potential of the oxidation branch is the oxidation potential of RM. .

[0058] According to some embodiments of the present application, the molar concentration of the redox pair may be 1mmol / L-100mmol / L, for example, 1mmol / L, 10mmol / L, 20mmol / L, 30mmol / L, 40mmol / L, 50mmol / L, 60mmol / L, 70mmol / L, 80mmol / L, 90mmol / L or 100mmol / L, etc., or may be a range composed of any of the above numerical values. Thus, the catalytic effect of the redox pair is improved and the decomposition voltage of the capacity compensator is reduced. At the same time, the viscosity of the electrolyte is reduced and the conductivity of the electrolyte is improved. According to some specific embodiments of the present application, the molar concentration of the redox pair may be 5mmol / L-50mmol / L. According to other specific embodiments of the present application, the molar concentration of the redox pair may be 10mmol / L-20mmol / L.

[0059] In the present application, the content of the redox pair can be tested by an Agilent 7890B gas chromatograph. Specifically, take the electrolyte sample to be analyzed and transfer it to the injection bottle, and arrange it in the injection plate. First, run the baseline until the baseline is stable, then edit and save the sequence of samples to be tested in the chemical worksheet, and run the sequence to start the test. Open the chemical workstation and call up the standard solution test spectrum. According to the peak area and sample weight of the standard solution, the relative response factor is calculated. The relative content of the redox pair can be calculated from the peak area of ​​the redox pair in the spectrum and the relative response factor of the standard solution.

[0060] According to some embodiments of the present application, the redox mediator may include at least one of an aromatic nitroxide free radical organic substance or a metal organic coordination compound. Thus, the redox mediator of the above type has only one oxidation potential, which can improve its catalytic efficiency, reduce the decomposition voltage of the capacity compensator, and improve the cycle capacity retention rate of the battery.

[0061] In the present application, "aromatic nitroxide free radical organic matter" refers to an organic matter containing both a piperidine group and a NO free radical.

[0062] According to some embodiments of the present application, the metal organic coordination compound includes metal ions and organic ligand ions, the metal ions include at least one of cobalt ions, zinc ions, copper ions, iron ions, nickel ions, manganese ions or ruthenium ions, and the organic ligand includes at least one of a phthalocyanine group, a terpyridine group, a cyclopentadiene group, a polypyridine group or a porphyrin group. Thus, the above-mentioned metal organic coordination compound has only one oxidation potential, which can improve its catalytic efficiency, reduce the decomposition voltage of the capacity compensator, and improve the cycle capacity retention rate of the battery.

[0063] According to some specific embodiments of the present application, the aromatic nitrogen oxide free radical organic matter includes at least one of 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 2-azaadamantane-N-oxyl free radical, 1-methyl-2-azaadamantane-N-oxyl free radical, 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide or tert-pentyl-tert-butylnitroxide. Thus, when the redox mediator is an aromatic nitrogen oxide free radical organic matter of the above type, the redox mediator has only one oxidation potential, and the catalytic capacity compensator decomposes as a single electron reaction, which can improve the catalytic efficiency of the redox mediator, reduce the decomposition voltage of the capacity compensator, improve the effect of capacity compensation, and improve the cycle capacity retention rate of the battery.

[0064] According to some specific embodiments of the present application, the metal organic coordination compound includes at least one of tetraphenylporphyrin iron, tetraphenylporphyrin nickel, tetraphenylporphyrin cobalt, tetraphenylporphyrin manganese, tetraphenylporphyrin zinc, iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, bis(terpyridine) cobalt, bis(terpyridine) iron, bis(terpyridine) manganese, ferrocene, nickelocene, cobaltocene, zincocene or rutheniumocene. Thus, when the redox mediator is a metal organic coordination compound of the above type, the redox mediator has only one oxidation potential, and the catalytic capacity compensator decomposes as a single electron reaction, which can improve the catalytic efficiency of the redox mediator, reduce the decomposition voltage of the capacity compensator, improve the effect of capacity compensation, and improve the cycle capacity retention rate of the battery.

[0065] According to some embodiments of the present application, the electrolyte may further include an additive, wherein the additive includes X ions, and the X ions may be combined with active ions to form a solid electrolyte membrane. Thus, after the redox medium is oxidized, the oxidized substances may shuttle between the positive electrode and the negative electrode, and the additive may reduce the consumption of active ions by the oxidized substances when shuttling to the negative electrode, thereby reducing the damage of the oxidized substances to the negative electrode.

[0066] According to some embodiments of the present application, the X ions may include at least one of fluoride ions or nitrogen ions. Thus, fluoride ions may be combined with active ions to form fluorides, and nitrogen ions may be combined with active ions to form nitrides, thereby reducing the consumption of active ions by oxidized substances formed by redox mediators and reducing the damage of oxidized substances to the negative electrode.

[0067] According to some embodiments of the present application, the additive includes a fluorine-containing amide additive or a nitrogen-containing amide additive. Thus, the fluorine-containing amide additive can release fluorine ions in the electrolyte, and the fluorine ions can combine with active ions to form fluorides; the nitrogen-containing amide additive can release nitrogen ions in the electrolyte, and the nitrogen ions can combine with active ions to form nitrides, thereby reducing the consumption of active ions by oxidized substances formed by redox mediators and reducing the damage of oxidized substances to the negative electrode.

[0068] According to some embodiments of the present application, the fluorine-containing amide additive may include at least one of N,N-dimethyl trifluoroacetamide, N,N-diethyl trifluoroacetamide, bis trifluoroacetamide, N-benzyl trifluoroacetamide, 4-N,N dimethylamino trifluoroacetophenone or bis (trimethylsilyl) trifluoroacetamide. Thus, the above-mentioned types of fluorine-containing amide additives can release fluoride ions in the electrolyte, and the fluoride ions can combine with active ions to form fluoride, thereby reducing the consumption of active ions by oxidized substances formed by redox mediators and reducing the damage of oxidized substances to the negative electrode.

[0069] According to some embodiments of the present application, the nitrogen-containing amide additive may include at least one of 2-amino-N,N-dimethylacetamide, 2-(4-aminophenyl)-N,N-dimethylacetamide or 2-(4-aminopiperidin-1-yl)-N,N-dimethylacetamide. Thus, the above-mentioned nitrogen-containing amide additives can release nitrogen ions in the electrolyte, and the nitrogen ions can combine with active ions to form nitrides, thereby reducing the consumption of active ions by oxidized substances formed by redox mediators and reducing the damage of oxidized substances to the negative electrode.

[0070] According to some embodiments of the present application, the ratio of the molar concentration of the redox pair to the molar concentration of the additive can be 100: (10-40), for example, it can be 100: 10, 100: 15, 100: 20, 100: 25, 100: 30, 100: 35 or 100: 40, etc., or it can be a range composed of any of the above numerical values. Thus, by making the ratio of the molar concentration of the redox pair to the molar concentration of the additive in the above range, the additive can be combined with the active ions, reducing the probability of the oxidized substances formed by the redox pair combining with the active ions, and reducing the damage of the oxidized substances to the negative electrode. According to some specific embodiments of the present application, the ratio of the molar concentration of the redox pair to the molar concentration of the additive can be 100: (15-25).

[0071] According to some embodiments of the present application, the molar concentration of the additive may be 0.1mmol / L-40mmol / L, for example, 0.1mmol / L, 1mmol / L, 5mmol / L, 10mmol / L, 15mmol / L, 20mmol / L, 25mmol / L, 30mmol / L, 35mmol / L or 40mmol / L, etc., or may be a range of any of the above numerical values. Thus, the probability of the additive binding to the active ions is increased, the probability of the oxidized substances formed by the redox mediator binding to the active ions is reduced, and the damage of the oxidized substances to the negative electrode is reduced. According to some embodiments of the present application, the molar concentration of the additive may be 0.75mmol / L-12.5mmol / L.

[0072] In this application, the content of the additive can be obtained by testing with an Agilent 7890B gas chromatograph. Specifically, take the electrolyte sample to be analyzed and transfer it to the injection bottle, and arrange it in the injection plate. First, run the baseline until the baseline is stable, then edit and save the sequence of samples to be tested in the chemical work, and run the sequence to start the test. Open the chemical workstation to call out the standard solution test spectrum, calculate the relative response factor based on the peak area of ​​the standard solution and the sample weight, and the relative content of the additive can be calculated from the peak area of ​​the additive in the spectrum and the relative response factor of the standard solution.

[0073] As an example, the electrolyte solution includes an electrolyte salt and a solvent.

[0074] In some embodiments, when the battery is a lithium battery, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0075] In some embodiments, when the battery is a sodium battery, the electrolyte salt may include at least one of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium tetrafluoroborate, sodium bisoxalatoborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, and sodium bis(trifluoromethylsulfonyl)imide.

[0076] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone, or diethyl sulfone.

[0077] In some embodiments, the electrolyte may also optionally include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives for improving battery overcharge performance, additives for improving battery high or low temperature performance, and the like.

[0078] The second aspect of the present application provides a battery, comprising the electrolyte provided in the first aspect of the present application, thereby improving the cycle capacity retention rate of the battery.

[0079] According to some embodiments of the present application, the battery includes a positive electrode sheet, the positive electrode sheet includes a positive current collector, at least one side of the positive current collector is provided with a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material and a capacity compensator. Thus, the capacity compensator can compensate for the loss of active ions, improve the initial efficiency of the battery, and improve the cycle capacity retention rate of the battery.

[0080] According to some embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensator can be 0.5%-20%, for example, it can be 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 15%, 18% or 20%, etc., or it can be a range composed of any of the above numerical values. Thus, by making the content of the capacity compensator within the above range, more active ions can be released during the battery cycle, thereby improving the first efficiency of the battery and improving the cycle capacity retention rate of the battery. According to some specific embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensator can be 1%-10%.

[0081] In this application, the content of the capacity compensator can be obtained by testing using a TGA-601 thermogravimetric analyzer. Scrape off the material on the positive electrode sheet, place the material in a thermogravimetric analyzer, introduce argon gas and heat it to 800°C to obtain a composite thermogravimetric curve of all materials in the positive electrode active material layer; take the pure capacity compensator material and obtain the thermogravimetric curve of the pure capacity compensator according to the above operation. By combining the two thermogravimetric curves, the content of the capacity compensator can be analyzed.

[0082] According to some embodiments of the present application, the volume average particle size D of the capacity compensating agent is v 50 can be 0.05 μm-30 μm, for example, 0.05 μm, 0.1 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm or 30 μm, or can be any range of the above values. v 50 In the above range, the decomposition difficulty of the capacity compensating agent is reduced, the utilization rate of the capacity compensating agent is improved, and the cycle capacity retention rate of the battery is improved. According to some specific embodiments of the present application, the volume average particle size D of the capacity compensating agent is v50 can be 0.05μm-15μm.

[0083] In this application, D v 50 refers to the particle size corresponding to the cumulative volume distribution percentage reaching 50%, for example, referring to the standard GB / T 19077-2016 / ISO 13320:2009, using a laser particle size analyzer (Malvern Master Size 2000) for measurement. The specific test process is: take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure 8%-12% shading), add 20ml of deionized water, and ultrasonicate for 5min (53KHz / 120W) to ensure that the sample is completely dispersed, and then measure the sample according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0084] According to some embodiments of the present application, the capacity compensator includes a lithium supplement and / or a sodium supplement, and the lithium supplement includes at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF; the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF. Therefore, when the battery is a lithium battery, the lithium supplement agent may include at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF to compensate for the lithium ions lost in the formation of SEI film and improve the first efficiency and cycle capacity retention rate of the battery; when the battery is a sodium battery, the capacity compensator may include at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF to compensate for the sodium ions lost in the formation of SEI film and improve the first efficiency and cycle capacity retention rate of the battery.

[0085] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0086] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material may adopt a positive electrode active material for lithium-ion batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0087] In some embodiments, such as when the battery is a sodium ion battery, as examples, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.

[0088] Examples of the layered transition metal oxides include:

[0089] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0090] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0091] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,0.67<d+e<0.8,b+c+d+e=1。

[0092] Examples of the polyanionic compound include:

[0093] A 1 f M 3 g (PO4) i O j X 1 3-j , where A 1 is one or more of H, Li, Na, K and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu and Zn, X 1 is one or more of F, Cl and Br, 0 <f≤4,0<g≤2,1≤i≤3,0≤j≤2;

[0094] Na n M 4 PO4X 2 , where M 4is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0095] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0096] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0097] As an example of the above Prussian blue analogs, for example, the following can be listed:

[0098] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + 、NH4 + 、an alkali metal cation, and an alkaline earth metal cation, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + 、Li + 、Na + 、K + 、NH4 + 、Rb + 、Cs + 、Fr + 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ and Ra 2+ among others, M 6 and M 7 are each independently cations of one or more transition metal elements among Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W.

[0099] The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0100] In some embodiments, the positive electrode active material layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0101] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the capacity compensating agent, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0102] In some embodiments, the battery further includes a negative electrode sheet, the negative electrode sheet includes a negative electrode collector and a negative electrode active material layer disposed on at least one surface of the negative electrode collector, the negative electrode active material layer including a negative electrode active material.

[0103] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is disposed on any one or both of the two facing surfaces of the negative electrode current collector.

[0104] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0105] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0106] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0107] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0108] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0109] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0110] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0111] In some embodiments, the material of the isolation membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0112] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0113] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0114] In some embodiments, the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0115] The present application has no particular limitation on the shape of the battery, which may be cylindrical, square or any other shape. Figure 1 The battery 5 is a square structure as an example.

[0116] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a top cover assembly 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0117] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0118] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the multiple batteries 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other manner. Further, the multiple batteries 5 can be fixed by fasteners.

[0119] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of batteries 5 are received in the receiving space.

[0120] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0121] Figure 4 and Figure 5 1 is a battery pack 1 as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0122] The third aspect of the present application provides an electric device, which includes at least one of the batteries, battery modules, or battery packs provided in the present application. The battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0123] As the electrical device, a battery, a battery module or a battery pack can be selected according to its usage requirements.

[0124] Figure 6 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of the battery, a battery pack or a battery module can be used.

[0125] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0126] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0127] Example 1

[0128] 1. Preparation of positive electrode sheet

[0129] Lithium iron phosphate material, lithium oxalate lithium supplement, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 92:5:1:2 to obtain a positive electrode slurry, and the positive electrode slurry is evenly coated on the positive electrode collector, and the positive electrode sheet is obtained after drying, cold pressing, and slitting.

[0130] 2. Preparation of negative electrode sheet

[0131] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in the solvent deionized water in a weight ratio of 96.2:0.8:0.8:1.2, mixed evenly to prepare the negative electrode slurry, and the negative electrode slurry is evenly coated on the negative electrode collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing and slitting.

[0132] 3. Preparation of electrolyte

[0133] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), the organic solvents ethylene carbonate (EC) / ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3:7, LiPF6, N,N-dimethyltrifluoroacetamide and ruthenocene were added thereto, and stirred uniformly to obtain an electrolyte with a LiPF6 concentration of 1 mol / L, an N,N-dimethyltrifluoroacetamide concentration of 5 mmol / L, and a ruthenocene concentration of 10 mmol / L.

[0134] 4. Isolation film

[0135] Polypropylene film is used as the isolation film.

[0136] 5. Preparation of batteries

[0137] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and then wound to obtain a bare cell, the bare cell is welded with a pole ear, and the bare cell is placed in an aluminum shell, baked at 80°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery. The uncharged battery then goes through the processes of static, hot and cold pressing, formation, shaping, capacity testing, etc. to obtain a battery product.

[0138] The preparation methods of the batteries in Examples 2 to 35 and Comparative Example 1 are the same as those in the Examples, and the differences are detailed in Table 1.

[0139]

[0140]

[0141]

[0142] Performance Testing

[0143] 1. Capacity compensator decomposition voltage test method

[0144] After the first week of charging, record the voltage (V) and capacity (Q) data of the charging process, and plot dQ / dV against V, and record the potential corresponding to the oxidation peak. The peak potential greater than 3.65V is the decomposition voltage of the capacity compensator.

[0145] 2. Cycle capacity retention rate test method

[0146] At 60°C, charge the battery to 3.65V at 1 / 3C constant current, charge to 0.05C at 3.65V constant voltage, leave for 5 minutes, and then discharge to the discharge cut-off voltage at 1 / 3C. The resulting capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery, and record the discharge capacity C0 of the battery after the nth cycle. n , then the battery capacity retention rate P after each cycle n =C n / C0*100%. In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 100th cycle corresponds to n=100. The data measured after 100 cycles under the above test conditions, i.e., P 100 The value of .

[0147] The test results of the batteries in Examples 1 to 35 and Comparative Example 1 are shown in Table 2.

[0148]

[0149]

[0150]

[0151] Conclusion: It can be seen from Table 2 that the decomposition voltages of the capacity compensating agents in Examples 1 to 35 are lower than that in Comparative Example 1, and the cycle capacity retention rates of the batteries in Examples 1 to 35 are higher than that in Comparative Example 1, indicating that the electrolyte proposed in the present application can reduce the decomposition voltage of the capacity compensating agent, improve the effect of capacity compensation, and improve the cycle capacity retention rate of the battery.

Claims

1. An electrolyte, characterized in that: The invention comprises a redox pair, wherein the redox pair has only one oxidation potential, and the oxidation potential of the redox pair is 3.4V-4.2V.

2. The electrolyte according to claim 1, characterized in that The oxidation potential of the redox couple is 3.5V-4V.

3. The electrolyte according to claim 1 or 2, characterized in that The molar concentration of the redox mediator is 1 mmol / L-100 mmol / L, and can be optionally 10 mmol / L-20 mmol / L.

4. The electrolyte according to any one of claims 1 to 3, characterized in that The redox mediator comprises at least one of an aromatic nitroxide free radical organic compound or a metal organic coordination compound.

5. The electrolyte according to claim 4, characterized in that The metal organic coordination compound includes metal ions and organic ligand ions, the metal ions include at least one of cobalt ions, zinc ions, copper ions, iron ions, nickel ions, manganese ions or ruthenium ions, and the organic ligands include at least one of phthalocyanine groups, terpyridine groups, cyclopentadiene groups, polypyridine groups or porphyrin groups.

6. The electrolyte according to claim 4 or 5, characterized in that Satisfy at least one of the following conditions: The aromatic nitroxide free radical organic matter includes at least one of 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 2-azaadamantane-N-oxyl free radical, 1-methyl-2-azaadamantane-N-oxyl free radical, 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide or tert-pentyl-tert-butyl nitroxide; The metal organic coordination compound includes at least one of tetraphenylporphyrin iron, tetraphenylporphyrin nickel, tetraphenylporphyrin cobalt, tetraphenylporphyrin manganese, tetraphenylporphyrin zinc, phthalocyanine iron, phthalocyanine cobalt, phthalocyanine nickel, bis(terpyridine) cobalt, bis(terpyridine) iron, bis(terpyridine) manganese, ferrocene, bis(terpyridine) nickel, bis(terpyridine) cobalt, bis(terpyridine) zinc or bis(terpyridine) ruthenium.

7. The electrolyte according to any one of claims 1 to 6, characterized in that The electrolyte solution further includes an additive, wherein the additive includes X ions, and the X ions can be combined with active ions to form a solid electrolyte membrane.

8. The electrolyte according to claim 7, characterized in that The X ions include at least one of fluorine ions or nitrogen ions.

9. The electrolyte according to claim 8, characterized in that The additive includes at least one of a fluorine-containing amide additive or a nitrogen-containing amide additive.

10. The electrolyte according to any one of claims 7 to 9, characterized in that: Satisfy at least one of the following conditions: The fluorine-containing amide additive includes at least one of N,N-dimethyl trifluoroacetamide, N,N-diethyl trifluoroacetamide, bis trifluoroacetamide, N-benzyl trifluoroacetamide, 4-N,N-dimethylamino trifluoroacetophenone or bis(trimethylsilyl) trifluoroacetamide; The nitrogen-containing amide additive includes at least one of 2-amino-N,N-dimethylacetamide, 2-(4-aminophenyl)-N,N-dimethylacetamide or 2-(4-aminopiperidin-1-yl)-N,N-dimethylacetamide.

11. The electrolyte according to any one of claims 7 to 10, characterized in that: The ratio of the molar concentration of the redox pair to the molar concentration of the additive is 100:(10-40), and can be optionally 100:(15-25).

12. The electrolyte according to any one of claims 7 to 11, characterized in that: The molar concentration of the additive is 0.1mmol / L-40mmol / L, and can be optionally 0.75mmol / L-12.5mmol / L.

13. A battery, characterized in that: The electrolyte comprising any one of claims 1 to 12.

14. The battery according to claim 13, characterized in that The battery comprises a positive electrode sheet, the positive electrode sheet comprises a positive current collector, at least one side of the positive current collector is provided with a positive electrode active material layer, and the positive electrode active material layer comprises a positive electrode active material and a capacity compensating agent.

15. The battery according to claim 13 or 14, characterized in that: Based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensating agent is 0.5%-20%, and can be optionally 1%-10%.

16. The battery according to any one of claims 13 to 15, characterized in that: The volume average particle size D of the capacity compensating agent v 50 is 0.05μm-30μm, and can be optionally 0.05μm-15μm.

17. The battery according to any one of claims 13 to 16, characterized in that: The capacity compensating agent includes a lithium supplement and / or a sodium supplement, wherein the lithium supplement includes at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF; the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF.

18. An electrical equipment, characterized in that: A battery comprising any one of claims 13 to 17.

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