Secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application relates to a secondary battery, comprising an electrolyte and a positive electrode plate, the electrolyte comprising a compound of formula (I), and the positive electrode plate comprising a positive electrode active material, the positive electrode active material having a surface residual lithium content of 20 ppm to 2000 ppm. The secondary battery of the present application has significantly improved cycle life and storage life. The present application also relates to a battery module, a battery pack and a power consumption device including the secondary battery. JPEG2024524797000015.jpg29170

Description

Technical Field

[0001] This application relates to the technical field of lithium batteries, and particularly to secondary batteries, battery modules, battery packs, and power consumption devices.

Background Art

[0002] As an energy storage system, secondary batteries are currently widely applied in daily life, such as in pure electric vehicles, hybrid electric vehicles, etc. People's requirements for the endurance of batteries are increasing. Therefore, in this field, secondary batteries with higher energy density are strongly demanded, and improving the operating potential of the battery is one of the important policies. However, at relatively high operating voltages, the stability of the interface between the positive and negative electrode plates and the electrolyte is poor, ultimately leading to deterioration of the cycle life and storage life of the battery.

[0003] In view of the above problems, in this field, secondary batteries with good cycle performance and / or storage performance at high operating voltages are required.

Summary of the Invention

[0004] This application is made in view of the above problems, and aims to provide a secondary battery and its battery module, battery pack, and power consumption device.

[0005] The first aspect of this application provides a secondary battery, which includes an electrolyte and a positive electrode plate, and the electrolyte contains a compound of formula (I), JPEG0007704873000001.jpg30170 Here, Q represents S or P, L is a single bond, an oxo group, or a C 1-6 alkylene group, C 1-6 alkyleneoxy group, C 2-6 alkenylene group, C 2-6 alkyleneoxy group, C 6-12An arylene group, C 6-12 An aryleneoxy group, C 1-6 An alkylene propyl-2-enyl group or a combination thereof, and in each case, the substituent is C 1-6 An alkyl group, C 2-6 An alkenyl group, C 2-6 An alkynyl group, a halogen or a cyano group, and when Q is S, m is 2 and n is 1, and when Q is P, m is 1 and n is 2, and the positive electrode plate contains a positive electrode active material, and the content of residual lithium on the surface of the positive electrode active material is 20 ppm by weight to 2000 ppm by weight.

[0006] Thereby, in the present application, the compound of formula (I) is contained in the electrolyte of the secondary battery, and by limiting the content of residual lithium on the surface of the positive electrode active material, the performance of the secondary battery at a relatively high operating voltage can be improved, and the cycle life and / or storage life can be improved.

[0007] In any embodiment, the content of residual lithium on the surface of the positive electrode active material is 20 ppm by weight to 1500 ppm by weight, optionally 100 ppm by weight to 1500 ppm by weight, and further optionally 200 ppm by weight to 1200 ppm by weight. By controlling the content of residual lithium on the surface, the cycle life and / or storage life of the secondary battery at a high operating voltage can be further improved.

[0008] In any embodiment, L is a single bond, an oxo group or a C 1-4 alkylene group, C 1-4 alkyleneoxy group, C 2-4 alkenylene group, C 2-4 alkyleneoxy group, C6 arylene group, C6 aryleneoxy group, C 1-4 alkylene propyl-2-enyl group or a combination thereof, and in each case, the substituent is C 1-4 alkyl group, C 2-4 alkenyl group, C 2-4Selected from an alkynyl group, a halogen or a cyano group, and optionally, said L is a single bond, an oxo group or a C which is optionally unsubstituted or mono- or polysubstituted with the same or different substituents 1-4 alkylene group, C 2-4 alkenylene group, C6 arylene group, C6 aryleneoxy group, C 1-4 represents an alkylene propyl-2-enyl group or a combination thereof, and in each case, the substituent is selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a vinyl group, an ethynyl group, fluorine or a cyano group, and further optionally, said L is a single bond or an unsubstituted C 1-2 alkylene group, C 2-4 represents an alkenylene group, a C6 arylene group or an aryleneoxy group.

[0009] As described above, by selecting the linking group L in the compound of formula (I), the cycle life and / or storage life of the secondary battery at a relatively high operating voltage can be further improved.

[0010] In any embodiment, the compound of the general formula (I) is at least one selected from the following, JPEG0007704873000002.jpg176170 Optionally, the compound of the general formula (I) is at least one selected from (I-1), (I-2), (I-3), (I-4), (I-5), (I-6), (I-7), (I-8) and (I-9).

[0011] As described above, by further selecting the compound of formula (I), the cycle life and / or storage life of the secondary battery at a high operating voltage can be better improved.

[0012] In any embodiment, the content of the compound of the formula (I) in the electrolyte is 0.01% by weight to 2 based on the total weight of the electrolyte 5 % by weight, optionally 0.1% by weight to 2 0By controlling the content of the compound of formula (I) within the above range, specifically by weight percentage, more selectively within the range of 0.15 wt% to 10 wt%, and even more selectively within the range of 0.15 wt% to 5 wt%, the cycle life and / or storage life of the secondary battery can be further improved, achieving a careful balance between both.

[0013] In any embodiment, the electrolyte further comprises one or more cathode film-forming additives selected from vinylene sulfate, polycyclic sulfate esters, lithium difluorophosphate, and lithium fluorosulfonate. By adding the above cathode film-forming additives, the cycle life and storage life of the secondary battery can be further improved significantly.

[0014] The second aspect of the present application provides a battery module including the secondary battery of the first aspect of the present application.

[0015] The third aspect of the present application provides a battery pack including the battery module of the second aspect of the present application.

[0016] The fourth aspect of the present application provides a power consumption device including at least one selected from the secondary battery of the first aspect of the present application, the battery module of the second aspect of the present application, or the battery pack of the third aspect of the present application.

[0017] The secondary battery of the present application has a high operating voltage and good cycle performance and / or storage performance, and can advantageously achieve a careful balance between both.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0019] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the secondary battery, battery module, battery pack, and power consumption device of the present application will be described in detail. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of structures that are actually the same may be omitted. This is to avoid making the following description unnecessarily long and to enable those skilled in the art to easily understand. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and do not limit the subject matter described in the claims.

[0020] The "ranges" disclosed in this application are limited in the form of a lower limit and an upper limit. A given range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. The ranges thus defined may or may not include the end values, and any combination is possible, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, it is understood that ranges of 60 - 110 and 80 - 120 are also conceivable. In addition, if the minimum range values 1 and 2 are listed, and the maximum range values 3, 4, and 5 are listed, all ranges of 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5 can be assumed. In this application, unless otherwise specified, the numerical range "a - b" represents a shortened expression of any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0 - 5" represents that all real numbers between "0 - 5" have already been listed in this specification, and "0 - 5" is only a shortened expression of these numerical combinations. Also, when a parameter is expressed as an integer ≧ 2, it is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] Unless otherwise specified, all embodiments and alternative embodiments of this application can be combined with each other to form new technical solutions.

[0022] Unless otherwise specified, all technical features and alternative technical features of this application can be combined with each other to form new technical solutions.

[0023] Unless otherwise specified, all steps of this application may be performed in sequence or randomly, and preferably, they are performed in sequence. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the fact that the method mentioned above may further include step (c) 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 steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0024] Unless otherwise specified, the terms "comprise" and "include" mentioned in this application represent an open type and may also be a closed type. For example, the "comprise" and "include" may further comprise or include other components not listed, or may comprise or include only the listed components.

[0025] Unless otherwise specified, the term "or" in this application is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any of the conditions where A is true (or exists) and B is false (or does not exist), where A is false (or does not exist) but B is true (or exists), and where both A and B are true (or exist) satisfy "A or B".

[0026] As an energy storage system, secondary batteries have now been widely applied in daily life, such as in pure electric vehicles, hybrid electric vehicles, etc. People's requirements for the endurance of batteries are increasing. Therefore, in this field, secondary batteries with higher energy density are strongly demanded, and improving the operating potential of the battery is one of the important policies. However, at relatively high operating voltages, the stability of the interfaces between the positive and negative electrode plates and the electrolyte deteriorates (for example, after multiple cycles, the thickness of the solid electrolyte interface (SEI) film increases), and the material of the positive electrode plate undergoes oxygen desorption, further deteriorating the stability of the positive electrode interface, ultimately leading to the deterioration of the cycle life and storage life of the battery.

[0027] This application provides a secondary battery that has good cycle performance and / or storage performance at a high operating voltage and ideally realizes the balance between the two.

[0028] Secondary battery

[0029] In one embodiment of this application, this application proposes a secondary battery, which includes an electrolyte and a positive electrode plate, and the electrolyte includes a compound of formula (I). JPEG0007704873000003.jpg27170 Here, Q represents S or P. L is a single bond, an oxo group, or a C 1-6 alkylene group, C 1-6 alkyleneoxy group, C 2-6 alkenylene group, C 2-6 alkyleneoxy group, C 6-12 arylene group, C 6-12 aryleneoxy group, C 1-6 alkylenepropyl-2-alkenyl group or a combination thereof, and in each case, the substituent is a C 1-6 alkyl group, C 2-6 alkenyl group, C 2-6Selected from an alkynyl group, a halogen or a cyano group, when Q is S, m is 2, and n is 1, when Q is P, m is 1, and n is 2, and the positive electrode plate contains a positive electrode active material, and the content of residual lithium on the surface of the positive electrode active material is 20 ppm by weight to 2000 ppm by weight.

[0030] In this specification, the positive electrode active material is a new material that has not been recycled.

[0031] As used herein, the term "residual lithium on the surface" means a basic lithium compound that is generated and present on the surface of the material particles during the production of the positive electrode active material or after being placed in air for a long time, and such a compound may be, for example, LiOH, Li2CO3 or LiHCO3. In some embodiments, the residual lithium on the surface is LiOH, Li2CO3 and / or LiHCO3 present on the surface of the positive electrode active material particles.

[0032] Generally, the content of residual lithium on the surface of the positive electrode active material can be determined by a normal basicity measurement method. For example, based on GB / T 9725-2007 Chemical Reagents - Potentiometric Titration Method, a hydrochloric acid standard solution is used to titrate the residual lithium on the surface (such as lithium carbonate, lithium hydrogen carbonate) in the positive electrode active material, a pH electrode is used as an indicator, the end point is determined by the jump point due to the potential change, and the content of the corresponding residual lithium can be calculated based on the hydrochloric acid consumption.

[0033] In this specification, "ppm by weight" has the same meaning as "ppm by mass". When not specifically indicated (for example, simply described as ppm), "ppm" represents "ppm by weight".

[0034] Without being bound by any theory, the inventors have found that by adding the compound of formula (I) to a secondary battery system, the performance of the secondary battery at a high operating voltage, such as cycle life and / or high-temperature storage life, can be significantly improved. In particular, the compound of formula (I) can improve the stability of the interfaces of both the positive electrode plate and the negative electrode plate at a relatively high operating voltage. The compound of formula (I) has both an isocyanate group (-N=C=O) and a fluorosulfonyl group (-SO2F) or a fluorophosphoryl group (-POF2), and can simultaneously exhibit the functional advantages of these two groups. For example, the isocyanate group can capture a small amount of acid and water generated by the electrolyte under voltage or high-temperature action, and can reduce the destruction of the SEI films on the positive and negative electrode plates by by-products generated by the oxidation of the electrolyte. On the other hand, the fluorosulfonyl group can form an SEI film, which is an inorganic component, on the surface of the negative electrode plate, and helps to improve the stability of the interface of the negative electrode. It should be noted that at a relatively high operating voltage, the problem of oxygen desorption on the surface of the positive electrode plate of the secondary battery is prominent, which further affects the stability of the interface of the positive electrode plate, and thus leads to problems in battery performance and safety. In this application, by adding the compound of formula (I) to the battery system, the problem of oxygen desorption can be improved, the positive electrode interface can be stabilized, and the battery performance can be improved. The fluorophosphoryl group can perform an action similar to that of the fluorosulfonyl group.

[0035] Without being bound by any theory, it has unexpectedly been found that the residual lithium on the surface of a positive electrode active material with a specific content can promote the action of the compound of formula (I) on the surface of the positive electrode plate. During the manufacture of a secondary battery, when an electrolyte is injected into the battery assembly and left standing, due to the presence of residual lithium on the surface with a specific content, the compound of formula (I) contained in the electrolyte tends to approach the positive electrode plate side. As a result, during the process of charging and discharging the battery at least once, the compound of formula (I) acts on the surface of the positive electrode, stabilizes the interface of the electrode plate, reduces oxygen desorption and the elution of metal ions, thereby improving the stability of the positive electrode interface at a high voltage and improving the life of the high-voltage battery system.

[0036] In some embodiments, the secondary battery is a lithium-ion secondary battery.

[0037] In some embodiments, the secondary battery is a high operating voltage secondary battery. The operating voltage of the secondary battery is at least 4.2 V, optionally at least 4.3 V, and further optionally at least 4.4 V.

[0038] In some embodiments, the content of residual lithium on the surface of the positive electrode active material is 20 to 1500 ppm by weight, optionally 100 to 1500 ppm by weight, and further optionally 200 to 1200 ppm by weight. By selecting the content of residual lithium on the surface, the cycle life and / or storage life of the secondary battery at a high operating voltage can be further improved.

[0039] In some embodiments, in formula (I), the L is a single bond, an oxo group, or a C alkylene group, a C alkyleneoxy group, a C alkenylene group, a C alkyleneoxy group, a C6 arylene group, a C6 aryleneoxy group, a C alkylene propyl-2-alkenyl group, or a combination thereof, each optionally unsubstituted or monosubstituted or polysubstituted with the same or different substituents, and in each case, the substituent is selected from a C alkyl group, a C alkenyl group, a C alkynyl group, a halogen, or a cyano group. 1-4 alkylene group, C 1-4 alkyleneoxy group, C 2-4 alkenylene group, C 2-4 alkyleneoxy group, C6 arylene group, C6 aryleneoxy group, C 1-4 alkylene propyl-2-alkenyl group or a combination thereof, and in each case, the substituent is a C 1-4 alkyl group, C 2-4 alkenyl group, C 2-4 alkynyl group, halogen, or cyano group.

[0040] In some embodiments, optionally, in formula (I), the L is a single bond, an oxo group, or a C alkylene group, a C alkenylene group, a C6 arylene group, a C6 aryleneoxy group, C 1-4 alkylene group, C 2-4 alkenylene group, C6 arylene group, C6 aryleneoxy group, C 1-4represents an alkylene propyl-2-alkenyl group or a combination thereof, and in each case, the substituent is selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a vinyl group, an ethynyl group, fluorine, or a cyano group.

[0041] In some embodiments, optionally, in formula (I), the L is a single bond, an oxo group, or a C 1-4 alkylene group, a C 2-4 alkenylene group, a C6 arylene group, or a C6 aryleneoxy group, and in each case, the substituent is selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a vinyl group, an ethynyl group, fluorine, or a cyano group. In some embodiments, further optionally, the L is a single bond or an unsubstituted C 1-2 alkylene group, a C 2-4 alkenylene group, a C6 arylene group, or an aryleneoxy group.

[0042] As described above, by selecting the linking group L in the compound of formula (I), the function of the functional group is exerted better, and the cycle life and / or storage life of the secondary battery at a relatively high operating voltage are further improved.

[0043] In some embodiments, the compound of formula (I) is at least one selected from the following, JPEG0007704873000004.jpg176170

[0044] In some embodiments, optionally, the compound of formula (I) is at least one selected from (I-1), (I-2), (I-3), (I-4), (I-5), (I-6), (I-7), (I-8), and (I-9).

[0045] As described above, by further selecting the compound of formula (I), the cycle life and storage life of the secondary battery at a high operating voltage can be better improved.

[0046] In some embodiments, here, the content of the compound of formula (I) in the electrolyte is 0.01% by weight to 20% by weight, optionally 0.1% by weight to 10% by weight, and further optionally 0.15% by weight to 5% by weight based on the total weight of the electrolyte. By controlling the content of the compound of formula (I) in the electrolyte within the above range, the cycle life and / or storage life of the secondary battery can be further improved.

[0047] In this specification, unless otherwise specified (for example, only described as "%"), "%" represents weight percentage (% by weight or wt%).

[0048] In some embodiments, the electrolyte is vinylene sulfate JPEG0007704873000005.jpg27170 Polycyclic sulfate JPEG0007704873000006.jpg26170 Further includes one or more cathode film-forming additives selected from lithium difluorophosphate (LiPO2F2) and lithium fluorosulfonate (LiSO3F). By further adding the above cathode film-forming additive to the electrolyte, the cycle life and storage life of the secondary battery can be further improved.

[0049] In some embodiments, the electrolyte further includes one or more aprotic organic solvents selected from fluorinated and non-fluorinated cyclic and chain organic carbonates, fluorinated and non-fluorinated ethers, fluorinated and non-fluorinated cyclic ethers, fluorinated and non-fluorinated carboxylic acid esters, fluorinated and non-fluorinated chain sulfones or cyclic sulfone compounds. By using the above electrolyte solvent, the oxidation resistance of the electrolyte at a high operating voltage can be improved, the oxidation of the cathode interface can be reduced, and it can further contribute to the improvement of the service life of the secondary battery.

[0050] In some embodiments, the positive electrode active material is at least one selected from an alkali metal-transition metal composite oxide, an alkali metal-transition metal phosphate compound, and a modified compound of the compound. In some embodiments, the alkali metal is selected from lithium, sodium, or potassium.

[0051] In some embodiments, the positive electrode active material is at least one selected from a lithium-transition metal composite oxide, a lithium-transition metal phosphate compound, and a deformed compound of the compound.

[0052] In some embodiments, optionally, the positive electrode active material is at least one selected from lithium cobalt oxide, lithium nickel oxide, lithium-rich manganese, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and a modified compound of the foregoing compounds.

[0053] In some embodiments, optionally, the positive electrode active material is LiCoO2, LiNiO2, LiMnO2, LiMn2O4, spinel-type LiNi 0.5 Mn 1.5 O4 (LNMO), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) and LiNi 0.8 C o 0.15 Al 0.05 O2 and is at least one selected therefrom.

[0054] By selecting and using the above positive electrode active material, the cycle and storage life of the secondary battery at a relatively high operating voltage can be improved.

[0055] In some embodiments, the type of particles of the positive electrode active material is single crystal or single crystal system particles. By manufacturing the electrode plate using single crystal or single crystal system particles of the positive electrode active material, the particles of the material are less likely to break, so that the probability of the material layer of the electrode plate being destroyed and a new interface (i.e., an interface where the SEI film layer is not formed) being exposed is reduced, the side reaction of the electrolyte is reduced, and finally the cycle life and storage life of the secondary battery can be further improved.

[0056] In some embodiments, the particle size of the single crystal or single crystal system particles of the positive electrode active material is 1 μm to 20 μm, and in some embodiments, optionally, the particle size is 3 μm to 15 μm. By selecting a positive electrode active material having a particle size within the above range, the particle size is relatively large, the specific surface area is relatively low, and the stability of the interface of the positive electrode plate is further improved, so that the cycle life and storage life of the secondary battery can be improved. However, if the particle size of the positive electrode active material is too large, the side reaction at the interface cannot be alleviated, and such a material has relatively poor processability.

[0057] In some embodiments, a coating may be applied to the surface of the positive electrode active material, and this coating is at least one coating element compound selected from oxides of coating elements, hydroxides of coating elements, oxyhydroxides of coating elements, carbonate oxides of coating elements, or hydroxycarbonates of coating elements, and the coating element is Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The stability of the interface of the positive electrode plate can be further improved.

[0058] In another aspect, the present application relates to the use of the compound of the general formula (I) for improving the stability of the interface of the positive electrode plate of a secondary battery. In particular, the secondary battery is a high operating voltage secondary battery.

[0059] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charge and discharge of the battery, active ions shuttle between the positive electrode plate and the negative electrode plate for insertion and desorption. The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The separator is installed between the positive electrode plate and the negative electrode plate, mainly serving to prevent short - circuit between the positive and negative electrodes and allowing ions to pass through. Each part of the secondary battery will be described in detail below.

[0060] [Positive Electrode Plate]

[0061] The positive electrode plate includes a positive electrode current collector and a positive electrode material layer disposed on at least one surface of the positive electrode current collector, and the positive electrode material layer contains the aforementioned positive electrode active material.

[0062] As an example, the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on one or both of the two opposing surfaces of the positive electrode current collector.

[0063] In some embodiments, the positive electrode current collector can be a metal foil sheet or a composite current collector. For example, as the metal foil sheet, aluminum foil can be used. The composite current collector may include a polymer - based material layer and a metal layer formed on at least one surface of the polymer - based material layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer - based material substrate (such as substrates of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0064] In some embodiments, the positive electrode film layer further selectively contains an adhesive. As an example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0065] In some embodiments, the positive electrode film layer further selectively contains a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0066] In some embodiments, the positive electrode plate can be manufactured by the following method. The above components for manufacturing the positive electrode plate, such as the positive electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is applied to the positive electrode current collector, and through processes such as drying and cold pressing, a positive electrode plate is obtained.

[0067] [Negative electrode plate]

[0068] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer contains a negative electrode active material.

[0069] As an example, the negative electrode current collector has two surfaces facing each other in its own thickness direction, and the negative electrode film layer is disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0070] In some embodiments, the negative electrode current collector can use a metal foil sheet or a composite current collector. For example, a copper foil can be used as the metal foil sheet. The composite current collector may include a polymer material-based layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (such as substrates of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0071] In some embodiments, the negative electrode active material can use a negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of materials such as artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be at least one selected from silicon alone, silicon oxide, silicon carbon composite, silicon nitride composite, and silicon alloy. The tin-based material may be at least one selected from tin alone, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials used as the negative electrode active material of the battery can also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0072] In some embodiments, the negative electrode film layer further selectively includes an adhesive. The adhesive may be selected from 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).

[0073] In some embodiments, the negative electrode film layer further selectively contains a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0074] In some embodiments, the negative electrode film layer further selectively contains other auxiliaries, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0075] In some embodiments, the negative electrode plate can be manufactured by the following method. The above components for manufacturing the negative electrode plate, such as the negative electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry. The negative electrode slurry is applied to the negative electrode current collector, and through processes such as drying and cold pressing, a negative electrode plate is obtained.

[0076] [Electrolyte]

[0077] The electrolyte functions to conduct ions between the positive electrode plate and the negative electrode plate. This application does not specifically limit the type of electrolyte, and it can be selected according to needs. For example, the electrolyte may be liquid, gel-like, or all-solid.

[0078] In some embodiments, an electrolytic solution is used as the electrolyte. The electrolytic solution contains an electrolyte salt and a solvent.

[0079] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0080] In some embodiments, the solvent may be selected from the aprotic organic solvents described above.

[0081] In some embodiments, the electrolyte may further selectively contain an additive. For example, the additive may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some performances of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, and the like.

[0082] [Separator]

[0083] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of the separator, and a known porous structure separator having excellent chemical stability and mechanical stability can be arbitrarily selected and used.

[0084] In some embodiments, the material of the separator may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, and there is no particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and there is no particular limitation.

[0085] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator can be used to manufacture an electrode assembly by a winding process or a lamination process.

[0086] In some embodiments, the secondary battery may include an outer package. This outer package may be used to package the above electrode assembly and electrolyte.

[0087] In some embodiments, the exterior body of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, a steel case, or the like. The exterior body of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0088] Battery module, battery pack, and power consumption device

[0089] A second aspect of the present application provides a battery module including the secondary battery of the first aspect of the present application.

[0090] A third aspect of the present application provides a battery pack including the battery module of the second aspect of the present application.

[0091] A fourth aspect of the present application provides a power consumption device including at least one selected from the secondary battery of the first aspect, the battery module of the second aspect, or the battery pack of the third aspect.

[0092] Hereinafter, the secondary battery, battery module, battery pack, and power consumption device of the present application will be described with appropriate reference to the drawings.

[0093] The present application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other arbitrary shape. For example, FIG. 1 shows a rectangular-structured secondary battery 5 as an example.

[0094] In some embodiments, referring to FIG. 2, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodation cavity. The case 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can be covered on the opening so as to seal the accommodation cavity. The positive electrode plate, the negative electrode plate and the separator can form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodation cavity. The electrolyte infiltrates the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select based on specific actual needs.

[0095] In some embodiments, the secondary battery can be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more. The specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0096] FIG. 3 shows a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in sequence in the longitudinal direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the plurality of secondary batteries 5 can be fixed by fastening tools.

[0097] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of secondary batteries 5 are accommodated in this accommodation space.

[0098] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. The specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0099] Figs. 4 and 5 show a battery pack 1 as an example. Referring to Figs. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3. The upper housing 2 is covered by the lower housing 3 and can form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0100] In addition, the present application further provides a power consumption device, which includes at least one of the secondary battery, battery module or battery pack according to the present application. The secondary battery, battery module, or battery pack may be used as a power source of the power consumption device, or may be used as an energy storage unit of the power consumption device. The power consumption device may include, but is not limited to, mobile devices (such as mobile phones, notebook computers, 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.

[0101] As the power consumption device, a secondary battery, battery module or battery pack can be selected based on its usage needs.

[0102] Fig. 6 shows a power consumption device as an example. This power consumption device is, for example, a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the needs for high power output and high energy density of the secondary battery of this power consumption device, a battery pack or battery module can be used.

[0103] As another example of the device, it may be a mobile phone, a tablet computer, a notebook computer, etc. This device usually requires thinning, and a secondary battery can be used as a power source.

[0104] Examples

[0105] Hereinafter, the secondary battery of the present application will be further described by combining examples. The examples described below are illustrative and are used only for the purpose of explaining the present application and should not be understood as limiting the present application. When specific technologies and conditions are not specified in the examples, follow the technologies and conditions described in the literature within the relevant field or follow the product manuals. Reagents or equipment not specified by the manufacturer are all ordinary commercially available products.

[0106] 1. Manufacture of Secondary Battery (1) Electrolyte In a glove box under an argon gas atmosphere (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate (EC) / ethyl methyl carbonate (EMC), which are organic solvents, were uniformly mixed at a mass ratio of 3 / 7, and LiPF6 lithium salt was added and dissolved in the above mixed solvent to obtain a 1 mol / L electrolyte solution. According to Table 1-3 below, the compound of formula (I) or the comparative compound in terms of weight percentage (wt%) based on the total weight of the electrolyte was added to the above solution respectively, and uniformly stirred to obtain an electrolyte.

[0107] Here, the names and structures of the compounds of formula (I-5), (I-6), (I-8) and (I-9) are as follows.

[0108] JPEG0007704873000007.jpg108170

[0109] (2) Positive Electrode Plate LiNi as the positive electrode active material 0.5 Co 0.2 Mn 0.3 O2 (NCM523), acetylene black as the conductive agent, and polyvinylidene fluoride (PVDF) as the adhesive were dissolved in the solvent N-methylpyrrolidone (NMP) at a weight ratio of 96:2:2, and stirred and mixed well to be homogenized to obtain a positive electrode slurry. Then, the positive electrode slurry was uniformly coated on the aluminum foil of the positive electrode current collector so that the coating weight was 0.018 g / cm 3 After that, the positive electrode plate was obtained by drying, cold pressing, and slitting.

[0110] (3) Negative electrode plate Artificial graphite as the negative active material, acetylene black as the conductive agent, styrene-butadiene rubber (SBR) as the adhesive, and sodium carboxymethyl cellulose (CMC-Na) as the thickener were dissolved in deionized water as the solvent at a weight ratio of 95:2:2:1, uniformly mixed to produce a negative electrode slurry, and the negative electrode slurry was uniformly coated on the negative electrode current collector copper foil so that the coating weight was 0.0112 g / cm 3 and dried to obtain a negative electrode plate, and the negative electrode plate was obtained by cold pressing and slitting.

[0111] (4) Separator: A normal polypropylene film was used as the separator.

[0112] (5) Lithium-ion secondary battery The positive electrode plate, separator, and negative electrode plate were laminated in sequence so that the separator was located between the positive and negative electrode plates to perform the isolation function, and then wound to obtain an electrode assembly. The electrode assembly was placed in a battery case, dried, and then the electrolyte was injected at an injection coefficient of 2.8 g / Ah. After passing through processes such as formation and standing, a lithium-ion secondary battery was manufactured.

[0113] 2. Test on the content of residual lithium on the surface of the positive active material Referring to GB / T 9725-2007 Chemical Reagents - Potentiometric Titration Method, the surface residual lithium (such as lithium carbonate and lithium hydrogen carbonate) in the positive active material was titrated using a hydrochloric acid standard solution, with a pH electrode as the indicator, and the end point was determined by the jump point due to the potential change. The corresponding content of residual lithium was calculated based on the hydrochloric acid consumption.

[0114] The specific operation is as follows. 30 g of the positive active material powder (new material that has not been recycled) to be tested was weighed, 100 ml of pure water was added, and after stirring for 30 min, it was allowed to stand for 10 min. After suction filtration, a certain amount of the filtrate was taken, and a 0.05 mol / L hydrochloric acid standard solution was selected and used for acid-base titration. The reaction was carried out in two steps, the "equivalence point (i.e., the end point of the reaction) 」There are two, and the volume of hydrochloric acid corresponding to the first "equivalence point" 」 is V1 (unit: ml), and the volume of hydrochloric acid corresponding to the second "equivalence point" 」 is V2 (unit: ml). The content of residual lithium in the corresponding positive electrode active material is calculated from the following formula and shown in Table 1-3 below.

[0115] Li2CO3%=(V2 - V1)*C*73.8909*n*100 / 1000m LiOH%=[V2 - 2*(V2 - V1)]*C*73.8909*n*100 / 1000m Li+%=V2*C*6.94*n*100 / (m*1000) The meanings of each quantity in the formula are as follows.

[0116] C is the concentration of the hydrochloric acid standard solution, mol / L, and here it is 0.05 mol / L. M is the mass of the sample, g. V1 is the volume of hydrochloric acid corresponding to the first "equivalence point" 」 in ml. V2 is the volume of hydrochloric acid corresponding to the second "equivalence point" 」 in ml.

[0117] 3. Quantitative analysis by positive electrode plate spectroscopy After discharging the secondary battery to 2.8 V at 0.33 C, it was disassembled to take out the corresponding positive electrode plate. After immersing it in dimethyl carbonate for 30 min, the dimethyl carbonate was replaced and immersion was continued, and this was repeated 3 times. After the immersed plate was vacuum dried at 25 °C for 30 min, quantitative analysis by spectroscopy was performed with reference to GB / T 17359-2012 / ISO 22309.

[0118] 4. 25 °C cycle performance test of lithium-ion secondary battery At 25°C, after the lithium-ion battery is charged at a constant current of 0.5C to 4.5V and then charged at a constant voltage of 4.5V until the current is less than 0.05C, discharging the lithium-ion battery at a constant current of 0.5C to 2.8V is one charge-discharge process. Charge and discharge are repeated in this way, and the number of cycles when the capacity retention rate reaches 80% is calculated.

[0119] 5. 60°C Storage Performance Test of Lithium-Ion Secondary Battery At 25°C, after the lithium-ion battery with an initial capacity of C0 is charged at a constant current of 0.5C to 4.5V and then charged at a constant voltage of 4.5V until the current is less than 0.05C, the cell is left at 60°C for storage, taken out every 5 days, fully charged, and stored at 60°C continuously. The storage days when the residual reversible capacity C1 corresponds to 80% are recorded. The test results are shown in Table 1-3.

[0120] 6. Reversible Capacity Test of Lithium-Ion Battery The battery capacity was measured at 25°C using a hope CHT3568 battery capacity measuring instrument for the reversible capacity of the lithium-ion battery.

[0121] The lithium-ion battery to be tested was placed at 25°C, charged at a constant current of 0.33C rate until the voltage reached 4.5V, then charged at a constant voltage until the current was 0.05C or less, and discharged at a constant current of 0.33C rate until the voltage reached 2.8V to measure the reversible capacity of the lithium-ion battery.

[0122] The above test results are shown in Table 1-4 below respectively.

[0123] Table 1 JPEG0007704873000008.jpg140170 * The contents of the comparative compounds isophorone diisocyanate and phenylmethylsulfonyl fluoride are 1 wt% each based on the total weight of the electrolyte so that the amounts of isocyanate groups and sulfonyl fluoride groups are equivalent to those of the example compounds respectively.

[0124] Table 2 JPEG0007704873000009.jpg129170

[0125] As shown in Table 1-2, when the electrolyte contains the compound of formula (I) and the content of residual lithium on the surface of the positive electrode active material is 20 - 2000 ppm by weight, the cycle life and high-temperature storage life of the secondary battery can be significantly improved.

[0126] Table 3 JPEG0007704873000010.jpg145170

[0127] As shown in Table 3, when the electrolyte contains 0.01 wt% - 2 5 wt% of the compound of formula (I), the cycle life and high-temperature storage life of the secondary battery can be improved. When the electrolyte further contains other film-forming additives, the performance of the secondary battery can be further improved.

[0128] In addition, quantitative analysis by spectroscopy was performed on the positive electrode plate and the negative electrode plate in Example 10. The analysis results are shown in Table 4 below.

[0129] Table 4 JPEG0007704873000011.jpg37170

[0130] As can be seen from Table 4, nitrogen elements corresponding to the compound of formula (I) are detected on the surface of the positive electrode plate, but the content of nitrogen elements detected on the surface of the corresponding negative electrode plate is extremely small, indicating that most of the added compound of formula (I) acts on the positive electrode.

[0131] It should be noted that this application is not limited to the above embodiments. The above embodiments are illustrative, and any embodiments that have a configuration substantially the same as the technical idea within the scope of the technical solution of this application and exhibit the same effects are included within the technical scope of this application. In addition, within the scope not departing from the gist of this application, various modifications conceivable by those skilled in the art to the embodiments, and other forms constituted by combining some components in the embodiments are also included within the scope of this application.

Description of Reference Numerals

[0132] 1 Battery pack, 2 Upper housing, 3 Lower housing, 4 Battery module, 5 Secondary battery, 51 Case, 52 Electrode assembly, 53 Cover plate

Claims

1. A secondary battery comprising an electrolytic solution and a positive electrode plate, wherein the electrolytic solution contains a compound of formula (I), wherein Q represents S or P, L represents a single bond, an oxo group, or a C １－６ alkylene group, C １－６ alkyleneoxy group, C ２－６ alkenylene group, C ２－６ alkyleneoxy group, C ６－１２ arylene group, C ６－１２ aryleneoxy group, C １－６ alkylenepropyl-2-alkenyl group or a combination thereof, and in each case, the substituent is C １－６ alkyl group, C ２－６ alkenyl group, C ２－６ alkynyl group, halogen or cyano group, and is selected from when Q is S, m is 2 and n is 1, when Q is P, m is 1 and n is 2, and the positive electrode plate contains a positive electrode active material, and the content of residual lithium on the surface of the positive electrode active material is 20 ppm by weight to 2000 ppm by weight, A secondary battery, wherein the content of the compound of formula (I) in the electrolytic solution is 0.01% by weight to 25% by weight based on the total weight of the electrolytic solution.

2. The secondary battery according to claim 1, wherein the content of residual lithium on the surface of the positive electrode active material is 20 ppm by weight to 1500 ppm by weight.

3. The L is a single bond, an oxo group, or a C １－４ alkylene group, a C １－４ alkyleneoxy group, a C ２－４ alkenylene group, a C ２－４ alkyleneoxy group, a C ６ arylene group, a C ６ aryleneoxy group, a C １－４ alkylenepropyl-2-alkenyl group or a combination thereof, and in each case, the substituent is a C １－４ alkyl group, a C ２－４ alkenyl group, a C ２－４ alkynyl group, halogen or a cyano group, and the secondary battery according to claim 1.

4. The compound of formula (I) is at least one selected from the following The secondary battery according to claim 1.

5. The secondary battery according to claim 1, wherein the content of the compound of formula (I) in the electrolytic solution is 0.1% by weight to 20% by weight based on the total weight of the electrolytic solution.

6. The secondary battery according to claim 1, wherein the electrolytic solution further contains one or more positive electrode film-forming additives selected from vinylene sulfate, polycyclic sulfate esters, lithium difluorophosphate, and lithium fluorosulfonate.

7. A battery module comprising the secondary battery according to any one of claims 1 to 6.

8. A battery pack comprising the battery module according to claim 7.

9. An electric power consumption device comprising the battery pack according to claim 8.

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