Electrolyte, battery, and electric device

Abstract

An electrolyte, a battery, and an electric device. The electrolyte comprises a lithium salt and a first additive, the first additive comprises a cyclic substance containing two sulfonic acid groups, and in the electrolyte, the range of the mass fraction w1 of the first additive satisfies: 0.01%≤w1≤2%.

Description

Electrolyte, batteries and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 2, 2024, with application number 2024101472003 and application name “Electrolyte, Battery and Electrical Equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to an electrolyte, a battery, and an electrical device. Background Art

[0003] With the rapid development of new energy technologies, the demand for battery cycle life is becoming increasingly stringent. Adding a small amount of lithium ferrite, a lithium supplement, to the positive electrode material can effectively offset the consumption of active lithium during cycling, thereby improving the battery's cycling performance. However, during the delithiation process, lithium ferrite undergoes a simultaneous oxidation reaction between iron and oxygen, which easily produces oxygen. This leads to oxidation of the electrolyte at the positive electrode, which not only consumes the electrolyte but also makes the electrolyte system unstable, reducing the battery's cycle life and safety performance.

[0004] Summary of the Invention

[0005] In view of this, the present application provides an electrolyte, a battery and an electrical device, wherein the electrolyte has good stability.

[0006] The present application provides an electrolyte, which includes a lithium salt and a first additive. The first additive includes a cyclic substance containing two sulfonate groups. In the electrolyte, the mass fraction w1 of the first additive is in the range of: 0.01%≤w1≤2%.

[0007] The present application also provides a battery, which includes: a negative electrode sheet, a separator, a positive electrode sheet and the electrolyte provided by the present application, wherein the separator is arranged on one side of the negative electrode sheet; the positive electrode sheet is arranged on the side of the separator away from the negative electrode sheet, the positive electrode sheet includes a positive electrode active layer and a positive electrode current collector layer, the positive electrode active layer is arranged on the surface of the positive electrode current collector layer, and the positive electrode active layer includes multiple lithium supplement particles; the electrolyte at least infiltrates a portion of the positive electrode sheet and a portion of the negative electrode sheet, and the electrolyte also includes a lithium salt.

[0008] The present application also provides an electrical device, which includes: a device body and a battery provided in the present application, and the battery supplies power to the device body.

[0009] In the present application, when the electrolyte is applied to a battery and the positive electrode of the battery includes lithium-supplementing particles, the lithium-supplementing particles can release lithium ions to make up for the lithium ions that are continuously consumed by the battery during the initial charge and discharge and continuous cycling process, thereby allowing the battery to have higher available energy. However, the lithium-supplementing particles release oxygen anions while releasing lithium ions. The oxygen anions have strong oxidizing properties and are prone to side reactions with the electrolyte, which reduces the stability of the electrolyte. However, in this solution, the electrolyte includes a first additive and the first additive includes a cyclic substance containing two sulfonate groups. The sulfur atom in the sulfonate group has a higher electron affinity and a higher electronegativity, and the bond energy of the sulfur-oxygen bond is lower. The cyclic structure is more unstable than the linear structure and has a higher reactivity, so that the first additive has a higher reduction potential and a lower oxidation potential. When the battery is charged, the potential of the positive electrode plate continuously rises, while the potential of the negative electrode plate continuously decreases. The first additive near the positive electrode plate reaches an oxidation potential before other substances, undergoes an oxidative decomposition reaction, and the resulting product adheres to the surface of the lithium-supplementing particles, thereby inhibiting the side reaction of oxygen anions or oxygen released by the lithium-supplementing particles with the electrolyte, which is beneficial for maintaining the stability of the electrolyte. Furthermore, the first additive near the negative electrode plate reaches a reduction potential before other substances, undergoes a reduction reaction, and the resulting product forms a film on the surface of the negative electrode plate, enhancing the strength of the interface film between the negative electrode plate and the electrolyte, thereby improving the capacity retention rate of the battery when the electrolyte is used in the battery. Furthermore, the reaction product of the first additive is primarily a sulfate-based substance, which does not generate a large amount of additional gas, further improving the safety performance of the battery when the electrolyte is used in the battery.

[0010] When the mass fraction w1 of the first additive satisfies the range of 0.01%≤w1≤2%, the mass fraction of the first additive is within a reasonable range. The first additive can not only perform redox reactions better than other substances in the electrolyte, but also form a film on the surface of the lithium-supplementing particles, thereby effectively preventing the oxygen released by the lithium-supplementing particles from reacting with the electrolyte. The product also forms a film on the surface of the negative electrode plate to enhance the strength of the interface film between the negative electrode plate and the electrolyte. The first additive can also be prevented from producing excessive acid and affecting the interface film between the positive electrode plate and / or the negative electrode plate and the electrolyte. Therefore, when the electrolyte is used in a battery, the battery has high energy efficiency, safety performance and capacity retention rate. When the mass fraction w1 of the first additive is too large, the products of the redox reaction of the first additive include acid. The excessive acid produced by the first additive will attack the interface film between the positive and / or negative electrode sheets and the electrolyte, thereby reducing the stability of the interface film between the positive and / or negative electrode sheets and the electrolyte, increasing the internal resistance of the battery, and subsequently reducing the charge and discharge efficiency, energy efficiency, and safety performance of the battery when the electrolyte is used. When the mass fraction w1 of the first additive is too small, the film formed by the products of the redox decomposition of the first additive is small, making it difficult for the first additive to prevent the oxygen released by the lithium-supplementing particles from reacting with the electrolyte, thereby reducing the stability of the electrolyte and thus reducing the capacity retention rate of the battery when the electrolyte is used. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0012] FIG1 is a schematic cross-sectional view of a battery according to an embodiment of the present application;

[0013] FIG2 is a schematic diagram of the cross-sectional structure of a positive electrode sheet according to an embodiment of the present application;

[0014] FIG3 is a scanning electron microscope image of the lithium-supplementing particles after shrinkage according to an embodiment of the present application;

[0015] FIG4 is a scanning electron microscope image of the lithium-supplementing particles after shrinkage according to another embodiment of the present application;

[0016] FIG5 is a circuit block diagram of an electric device according to an embodiment of the present application;

[0017] FIG6 is a schematic structural diagram of an electrical device according to an embodiment of the present application.

[0018] Description of reference numerals:

[0019] 100-electrolyte, 200-battery, 210-negative electrode sheet, 220-diaphragm, 230-positive electrode sheet, 231-positive electrode active layer, 232-positive electrode current collector layer, 300-electrical equipment, 310-equipment body. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0021] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0022] References herein to "embodiments" or "implementations" mean that a particular feature, structure, or characteristic described in connection with the embodiments or implementations may be included in at least one embodiment of the present application. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor do they constitute independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] With the rapid development of new energy technologies, the requirements for battery cycle life are becoming increasingly higher. Among them, adding a small amount of lithium supplement lithium ferrite to the positive electrode material can effectively compensate for the consumption of active lithium during the cycle, thereby improving the cycle performance of the battery. However, during the delithiation process, lithium ferrite will undergo an oxidation reaction of iron and oxygen, which makes it easy to produce oxygen, causing the electrolyte to oxidize at the positive electrode plate, which not only consumes the electrolyte, but also makes the electrolyte system unstable, reducing the cycle life and safety performance of the battery. When lithium ferrite releases more lithium during the delithiation process, lithium ferrite will also release more oxygen at the same time, causing the positive electrode material and the electrolyte to undergo more side reactions, reducing the safety performance of the battery; when lithium ferrite releases fewer lithium ions during the delithiation process, it is difficult to compensate for the consumption of active lithium during the cycle, thereby reducing the cycle performance of the battery.

[0024] Referring to Figures 1 and 2, an embodiment of the present application provides an electrolyte 100, wherein the electrolyte 100 includes a first additive, wherein the first additive includes a cyclic substance containing two sulfonate groups, and in the electrolyte 100, the mass fraction w1 of the first additive is in the range of: 0.01%≤w1≤2%.

[0025] Specifically, the mass fraction w1 of the first additive may be, but is not limited to, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.45%, 0.55%, 0.65%, 0.7%, 0.85%, 0.9%, 1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.45%, 1.55%, 1.65%, 1.75%, 1.8%, 1.85%, 1.9%, 1.95% and 2%, etc.

[0026] It can be understood that the mass fraction w1 of the first additive is the ratio of the mass of the first additive to the mass of the electrolyte 100 .

[0027] It can be understood that the electrolyte 100 is applied to a battery 200, which is a lithium-ion battery. The electrolyte 100 includes a lithium salt. The battery 200 also includes a negative electrode sheet 210, a separator 220, and a positive electrode sheet 230. The positive electrode sheet 230 includes a positive active layer 231 and a positive current collector layer 232. The positive active layer 231 is disposed on the surface of the positive current collector layer 232 and includes lithium-supplementing particles. The electrolyte 100 at least partially infiltrates the positive electrode sheet 230 and the negative electrode sheet 210. During the charge and discharge process of the battery 200, the electrolyte 100 acts as a transport medium for active ions, that is, a transport medium for lithium ions. On the one hand, it can provide some active lithium ions for use as conductive ions; on the other hand, the electrolyte 100 can provide ion channels to help lithium ions move freely in the battery 200. The lithium-replenishing particles can release lithium ions when the battery 200 is charged, thereby replenishing the active ions consumed in the electrolyte 100 in a timely manner.

[0028] It can be understood that the first additive includes a cyclic substance containing two sulfonate groups, and the sulfur atom in the sulfonate group has a high electron affinity, which can attract electrons, thereby increasing the electron cloud density around the sulfur atom, and the sulfur atom has a high electronegativity, making the sulfonate group more likely to accept electrons, thereby making the sulfonate group have a higher reduction potential, that is, the first additive has a higher reducing ability. Further, the bond energy of the sulfur-oxygen bond in the sulfonate group is relatively low, which makes it easier for the sulfur-oxygen bond to break during the oxidation reaction, thereby making the sulfonate group have a lower oxidation potential. Further, the first additive is a cyclic substance, which is less stable than a linear structure, making the first additive more susceptible to redox reactions than other components in the electrolyte 100.

[0029] When the electrolyte 100 is applied to the battery 200 and the battery 200 is charged, the potential of the positive electrode plate 230 continues to rise, and the potential of the negative electrode plate 210 continues to fall. In the electrolyte 100 near the positive electrode plate 230, the oxidation potential of the first additive is relatively low, and the first additive is more likely to reach the oxidation potential than other components, so that the first additive undergoes an oxidation reaction preferentially compared to other components; in the electrolyte 100 near the negative electrode plate 210, the reduction potential of the first additive is relatively high, and the first additive is more likely to reach the reduction potential than other components, so that the first additive undergoes a reduction reaction preferentially compared to other components. Furthermore, the first additive is a cyclic substance, which has poorer stability than a linear structure, making the first additive more likely to undergo an oxidation-reduction reaction than other components in the electrolyte 100. In summary, in the electrolyte 100, the first additive undergoes an oxidation reaction and a reduction reaction preferentially compared to other components.

[0030] In this embodiment, when the electrolyte 100 is applied to the battery 200 and the positive electrode 230 of the battery 200 includes lithium-supplementing particles, the lithium-supplementing particles can release lithium ions to compensate for the lithium ions continuously consumed by the battery 200 during the initial charge and discharge and continued cycling, thereby enabling the battery 200 to have a higher usable energy. However, when releasing lithium ions, the lithium-supplementing particles also release oxygen anions. These oxygen anions have strong oxidizing properties and are prone to side reactions with the electrolyte 100, reducing the stability of the electrolyte 100. However, in this embodiment, the electrolyte 100 includes a first additive, and the first additive includes a cyclic substance containing two sulfonate groups. The sulfur atoms in the sulfonate groups have a high electron affinity and high electronegativity, and the sulfur-oxygen bond has a low bond energy. The cyclic structure is more unstable than the linear structure and has higher reactivity, resulting in the first additive having a higher reduction potential and a lower oxidation potential. When the battery 200 is charged, the potential of the positive electrode plate 230 continuously rises, while the potential of the negative electrode plate 210 continuously decreases. The first additive near the positive electrode plate 230 reaches an oxidation potential before other substances. The first additive undergoes an oxidative decomposition reaction, and the resulting product adheres to the surface of the lithium-supplementing particles, thereby inhibiting side reactions between the oxygen anions or oxygen released by the lithium-supplementing particles and the electrolyte 100, thereby maintaining the stability of the electrolyte 100. Furthermore, the first additive near the negative electrode plate 210 reaches a reduction potential before other substances. The product of the first additive's reduction reaction forms a film on the surface of the negative electrode plate 210, strengthening the interfacial film between the negative electrode plate 210 and the electrolyte 100, thereby improving the capacity retention of the battery 200 when the electrolyte 100 is used in the battery 200. Furthermore, the reaction product of the first additive is primarily sulfate, which does not generate a large amount of additional gas, further improving the safety performance of the battery 200 when the electrolyte 100 is used in the battery 200.

[0031] When the mass fraction w1 of the first additive satisfies the range of 0.01% ≤ w1 ≤ 2%, the mass fraction of the first additive is within a reasonable range. The first additive can not only undergo redox reactions better than other substances in the electrolyte 100, but also form a film on the surface of the lithium-supplementing particles, thereby effectively preventing the oxygen released by the lithium-supplementing particles from undergoing side reactions with the electrolyte 100. The product also forms a film on the surface of the negative electrode plate 210 to enhance the strength of the interface film between the negative electrode plate 210 and the electrolyte 100. The first additive can also be prevented from producing excessive acid and affecting the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100. Therefore, when the electrolyte 100 is applied to the battery 200, the battery 200 has high energy efficiency, safety performance, and capacity retention. When the mass fraction w1 of the first additive is too large, the products of the redox reaction of the first additive include acid. The excessive acid produced by the first additive will attack the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby reducing the stability of the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, increasing the internal resistance of the battery 200, and subsequently reducing the charge and discharge efficiency, energy efficiency, and safety performance of the battery 200 when the electrolyte 100 is used in the battery 200. When the mass fraction w1 of the first additive is too small, the film formed by the products of the redox decomposition of the first additive is too small, making it difficult for the first additive to prevent the oxygen released by the lithium supplement particles from reacting with the electrolyte 100, thereby reducing the stability of the electrolyte 100 and reducing the capacity retention rate of the battery 200 when the electrolyte 100 is used in the battery 200.

[0032] In some embodiments, the first additive has the structural formula: Wherein, said R1 is selected from H, C, C n H 2n+2 and C6H6; R2 is selected from H, C, C n H 2n+2 and one of C6H6, and n satisfies the range: 1≤n≤10.

[0033] Here, the value of n is selected from one of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0034] In this embodiment, as can be seen from the structural formula of the first additive, the first additive includes a cyclic substance containing two sulfonate groups. The cyclic structure of the first additive makes the structural stability of the first additive relatively poor, which in turn makes the first additive more reactive than other components in the electrolyte 100. When the electrolyte 100 includes the first additive and the first additive is applied to the battery 200, both of the sulfonate groups contain sulfur. The sulfur atoms have high electronegativity and electron affinity, resulting in a high electron cloud density around the sulfur atoms, which in turn gives the first additive a higher reduction potential. The two sulfonate groups also have multiple sulfur-oxygen bonds, and the bond energy of the sulfur-oxygen bonds is low, which gives the first additive a lower oxidation potential. When the electrolyte 100 is applied to the battery 200 and the battery 200 is charged, the potential of the positive electrode plate 230 continues to rise and the potential of the negative electrode plate 210 continues to decrease. In the electrolyte 100 near the positive electrode plate 230, the oxidation potential of the first additive is low. As the potential of the positive electrode plate 230 increases, the first additive is more likely to undergo oxidative decomposition than other components; in the electrolyte 100 near the negative electrode plate 210, the reduction potential of the first additive is high. As the potential of the negative electrode plate 210 decreases, the first additive is more likely to undergo reductive decomposition than other components. The decomposition products of the first additive during the oxidation reaction adhere to the surface of the lithium-supplementing particles and form a film on the surface of the lithium-supplementing particles, thereby preventing the electrolyte 100 from reacting with the oxygen generated by the lithium-supplementing particles, thereby maintaining the stability of the electrolyte 100. The decomposition products of the first additive during the reduction reaction form a film on the surface of the negative electrode plate 210, thereby strengthening the interface film between the negative electrode plate 210 and the electrolyte 100, thereby improving the cycle performance and capacity retention of the battery 200 when the electrolyte 100 is used in the battery 200. R1 and R2 are selected from a hydrogen atom, a carbon atom, a saturated chain alkane having an atomic number of 1 to 10, or a benzene ring, so as to prevent R1 and R2 from lowering the reduction potential of the first additive or increasing the oxidation potential of the first additive.

[0035] In some embodiments, the electrolyte 100 further includes a second additive, the second additive is a film-forming additive, the reduction potential of the first additive is higher than the reduction potential of the second additive, and the oxidation potential of the first additive is lower than the oxidation potential of the second additive. In the electrolyte 100, the mass fraction of the second additive is w2, then the relationship is satisfied: 2≤w2 / w1≤10.

[0036] Specifically, the value of w2 / w1 can be, but is not limited to, 2, 2.3, 2.5, 2.8, 3, 3.2, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.6, 5.9, 6, 6.2, 6.5, 6.8, 7, 7.5, 7.8, 8, 8.3, 8.8, 8.9, 9, 9.3, 9.5, 9.8 and 10, etc.

[0037] In this embodiment, the electrolyte 100 also includes a second additive and the second additive is a film-forming additive. When the electrolyte 100 is applied to the battery 200, the second additive is beneficial to promote the formation of an interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, and can maintain the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, so as to avoid the internal resistance of the battery 200 from increasing due to the destruction of the interface film when the electrolyte 100 is applied to the battery 200, thereby making the battery 200 have higher energy efficiency when the electrolyte 100 is applied to the battery 200. Furthermore, the reduction potential of the first additive is higher than the reduction potential of the second additive, and the oxidation potential of the first additive is lower than the oxidation potential of the second additive. Then, when the electrolyte 100 is applied to the battery 200 and the battery 200 is charged, the potential of the positive electrode plate 230 continues to rise, and the first additive reaches the oxidation potential earlier than the second additive, so that the first additive undergoes an oxidation reaction preferentially compared to the second additive; the potential of the negative electrode plate 210 continues to decrease, and the first additive reaches the reduction potential earlier than the second additive, so that the first additive undergoes a reduction reaction preferentially compared to the second additive, which can prevent the second additive from being decomposed and unable to function normally, so that the second additive can promote the formation of an interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100 and maintain the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100.

[0038] When the electrolyte 100 satisfies the relationship: 2≤w2 / w1≤10, the mass fraction of the first additive and the mass fraction of the second additive are both within a reasonable range. The first additive not only produces sufficient decomposition products to cover the surface of the lithium-supplementing particles and slow the reaction between the oxygen generated by the lithium-supplementing particles and the electrolyte 100, but also forms a film on the surface of the negative electrode plate 210 to enhance the strength of the interface film between the negative electrode plate 210 and the electrolyte 100. This also prevents excessive acid production due to an excessive amount of the first additive, and prevents waste of the second additive due to insufficient first additive. Ultimately, the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100 has good stability, and the electrolyte 100 has good stability, resulting in high charge and discharge efficiency, energy efficiency, and safety performance for the battery 200. When the value of w2 / w1 is too large, the mass fraction of the first additive is much smaller than the mass fraction of the second additive. On the one hand, if the mass fraction of the first additive is too low, the decomposition products of the first additive are too few and difficult to form a film on the surface of the lithium-supplementing particles or the surface of the negative electrode plate 210. This makes it difficult to mitigate the side reaction between the oxygen generated by the lithium-supplementing particles and the electrolyte 100, and it is difficult to enhance the strength of the interface film between the negative electrode plate 210 and the electrolyte 100. The stability of the electrolyte 100 is poor, resulting in a low capacity retention rate of the battery 200. On the other hand, if the mass fraction of the second additive is too high, when the battery 200 is charged, the first additive preferentially undergoes redox decomposition and is completely consumed, while some of the second additive still undergoes redox decomposition and produces gas, resulting in waste of the second additive. The gas generated by the second additive is not conducive to the cycle of the battery 200, and may increase side reactions between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, reducing the stability of the electrolyte 100, thereby increasing the internal resistance of the battery 200 and reducing the capacity retention rate and energy efficiency of the battery 200. When the value of w2 / w1 is too small, the mass fraction of the first additive is much greater than the mass fraction of the second additive. On the one hand, if the mass fraction of the first additive is too high, the redox decomposition of the first additive will produce excessive acid, which will attack the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby reducing the stability of the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, increasing the internal resistance of the battery 200, and subsequently reducing the charge and discharge efficiency, energy efficiency, and safety performance of the battery 200 when the electrolyte 100 is used in the battery 200.On the other hand, the mass fraction of the second additive is too small, making it difficult for the second additive to promote the formation of an interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, and to maintain the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, which may increase the internal resistance of the battery 200, thereby reducing the energy efficiency of the battery 200.

[0039] In some embodiments, the mass fraction w2 of the second additive satisfies the range: 1%≤w2≤4%.

[0040] Specifically, the mass fraction w2 of the second additive can be, but is not limited to, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 1.9%, 2%, 2.1%, 2.3%, 2.5%, 2.7%, 2.9%, 3%, 3.1%, 3.3%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% and 4%, etc.

[0041] In this embodiment, when the mass fraction w2 of the second additive satisfies the range of 1%≤w2≤4%, the mass fraction of the second additive is within a reasonable range. The second additive can not only promote the formation of an interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, but also maintain the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100. It can also avoid gas production due to excessive amount of the second additive, thereby improving the safety performance and cycle performance of the electrolyte 100 applied to the battery 200, and also helping to improve the energy efficiency of the battery 200. When the mass fraction of the second additive is too large, when the battery 200 is charged, after the first additive undergoes preferential redox decomposition and is consumed, some of the second additive still undergoes redox decomposition and produces gas, resulting in waste of the second additive. The gas produced by the second additive is not conducive to the circulation of the battery 200 and may increase side reactions between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby increasing the internal resistance of the battery 200 and reducing the energy efficiency of the battery 200. When the mass fraction of the second additive is too small, it is difficult for the second additive to promote the formation of an interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, and to maintain the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, which may increase the internal resistance of the battery 200 and reduce the energy efficiency of the battery 200.

[0042] In some embodiments, the second additive includes at least one of vinylene carbonate, fluoroethylene carbonate, vinyl sulfate, tris(trimethylsilyl)phosphate, 1,3-propane sultone, adiponitrile, succinonitrile, and 1,3,6-hexanetrinitrile.

[0043] It can be understood that, in the terminology of this application, "at least one" means greater than or equal to one, and can be one or more.

[0044] In this embodiment, when at least one of vinylene carbonate, fluorocarbonate, vinyl sulfate, tris(trimethylsilyl) phosphate, 1,3-propane sultone, adiponitrile, succinonitrile, and 1,3,6-hexanetrionitrile is applied to the electrolyte 100, it can promote the formation of an interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, and can promote the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby avoiding the interface film from being destroyed and increasing the internal resistance of the battery 200, so that when the electrolyte 100 is applied to the battery 200, the battery 200 has a higher capacity retention rate and safety performance.

[0045] An embodiment of the present application provides a battery 200, which includes: a negative electrode sheet 210, a separator 220, a positive electrode sheet 230, and an electrolyte 100 provided in the present application, wherein the separator 220 is arranged on one side of the negative electrode sheet 210; the positive electrode sheet 230 is arranged on the side of the separator 220 away from the negative electrode sheet 210, the positive electrode sheet 230 includes a positive electrode active layer 231 and a positive electrode current collector layer 232, the positive electrode active layer 231 is arranged on the surface of the positive electrode current collector layer 232, and the positive electrode active layer 231 includes multiple lithium supplement particles; the electrolyte 100 at least infiltrates a portion of the positive electrode sheet 230 and a portion of the negative electrode sheet 210.

[0046] It can be understood that the negative electrode plate 210 , the separator 220 and the positive electrode plate 230 are arranged in sequence.

[0047] It can be understood that in the battery 200, the electrolyte 100 includes lithium salt, and the electrolyte 100 includes active ions, i.e., lithium ions; the positive electrode plate 230 and the negative electrode plate 210 are at least partially immersed in the electrolyte 100. During the charging and discharging process of the battery 200, the electrolyte 100 serves as a transmission medium for active ions, i.e., a transmission medium for lithium ions. On the one hand, it can provide some active lithium ions for use as conductive ions; on the other hand, the electrolyte 100 can provide ion channels to help lithium ions move freely in the battery 200.

[0048] In the battery 200 provided in this embodiment, the positive active layer 231 of the positive electrode plate 230 includes lithium-replenishing particles. When the positive electrode plate 230 is applied to the battery 200 and the battery 200 is charged, the lithium-replenishing particles can release lithium ions. The lithium ions are transferred from the positive electrode plate 230 to the electrolyte 100 and then to the negative electrode plate 210, thereby replenishing the lithium ions in the battery 200 and improving the first efficiency, energy density and capacity retention rate of the battery 200. In addition, the battery 200 includes the electrolyte 100 provided in the present application, which at least partially infiltrates the positive electrode sheet 230 and the negative electrode sheet 210. The electrolyte 100 includes a first additive. The first additive can preferentially undergo an oxidation-reduction reaction compared to other components in the electrolyte 100. The oxidative decomposition products of the first additive adhere to the surface of the lithium-supplementing particles and slow down the side reaction between the oxygen generated by the lithium-supplementing particles and the electrolyte 100. The reduced decomposition products of the first additive form a film on the surface of the negative electrode sheet 210 to enhance the strength of the interface film between the negative electrode sheet 210 and the electrolyte 100, which is beneficial for maintaining the stability of the electrolyte 100 and improving the capacity retention rate of the battery 200. In addition, the reaction products of the first additive are mainly sulfate substances, which do not generate a large amount of additional gas, resulting in the battery 200 having a high capacity retention rate and good safety performance.

[0049] Optionally, the battery 200 may be a cylindrical battery, a square battery, a soft-pack battery, or the like.

[0050] Optionally, the material of the diaphragm 220 is selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. In some embodiments, the diaphragm 220 is a single-layer film; in other embodiments, the diaphragm 220 is a multi-layer composite film. When the diaphragm 220 is a multi-layer composite film, the materials of each layer can be the same or different.

[0051] Optionally, the thickness of the diaphragm 220 ranges from 14 μm to 18 μm. Specifically, the thickness of the diaphragm 220 may be, but is not limited to, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, and 18 μm.

[0052] Optionally, the positive electrode active layer 231 further includes a positive electrode active material selected from at least one of a lithium transition metal oxide and a modified material thereof. In some embodiments, the positive electrode active material is lithium iron phosphate. The modified material may be a lithium transition metal oxide that has been doped and / or coated. Preferably, the lithium transition metal oxide may be, but is not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide.

[0053] Optionally, the material of the positive electrode current collector layer 232 is selected from aluminum.

[0054] Optionally, the positive electrode active layer 231 further includes a positive electrode binder and a positive electrode conductor. In the positive electrode active layer 231 , the positive electrode binder is used to bond the components in the positive electrode active layer 231 to improve the overall performance of the positive electrode plate 230 ; the positive electrode conductor can improve the conductivity of the positive electrode active layer 231 .

[0055] Optionally, the positive electrode binder is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride and polytetrafluoroethylene.

[0056] Optionally, the positive electrode conductive agent is selected from at least one of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0057] Optionally, the negative electrode plate 210 includes a negative electrode current collector layer (not shown) and a negative electrode active layer (not shown), wherein the negative electrode active layer is arranged on the surface of the negative electrode current collector layer, and the negative electrode active layer includes a negative electrode active material, and the negative electrode active material is selected from at least one of metallic lithium, artificial graphite, natural graphite, graphene and other composite materials.

[0058] Optionally, the negative electrode current collector layer is selected from copper.

[0059] Optionally, the negative electrode active layer further includes a negative electrode binder, a negative electrode conductor and a negative electrode thickener. The negative electrode binder is used to bind the components in the negative electrode active layer to improve the overall performance of the negative electrode active layer; the negative electrode conductor is used to improve the conductivity of the negative electrode active layer; and the thickener is used to improve the adhesion of the negative electrode active layer.

[0060] Optionally, the negative electrode conductive agent is selected from at least one of acetylene black, conductive carbon black, carbon nanotubes, carbon fibers, graphene, and the like.

[0061] Optionally, the negative electrode binder includes at least one of asphalt binder, styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyacrylate, carboxymethyl cellulose (CMC), sodium alginate, etc.

[0062] Optionally, the negative electrode thickener is selected from at least one of sodium carboxymethyl cellulose (CMC), polyacrylamide (PAM), polymethacrylate (PMA), etc.

[0063] In some embodiments, in the positive electrode active layer 231, the mass fraction of the lithium supplement particles is w3. The lithium supplement particles include a matrix and a coating layer. The coating layer is disposed on the outer periphery of the matrix. The planar shrinkage rate of the matrix is α. Then, the relational expression is satisfied: 0.4 ≤ α × w3 / w1 ≤ 1.7; wherein, the chemical formula of the matrix is Li 1+r M 1-p N p O 4-s B s , and 0.1 < r < 6.1, 0 ≤ p < 0.99, 0 ≤ s < 0.1 are satisfied; M and N are each independently selected from at least one of iron, cobalt, nickel, titanium, zinc, magnesium, aluminum, manganese, vanadium, chromium, zirconium, copper, niobium, tantalum, tungsten, yttrium, and lanthanum, and B is selected from at least one of sulfur, nitrogen, fluorine, chlorine, and bromine.

[0064] Specifically, the value of α × w3 / w1 can be, but is not limited to, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, etc.

[0065] It can be understood that the chemical formula of the matrix 1211 is Li 1+r M 1-p N p O 4-s B s , then the matrix 1211 is formed by Li 1+r M 1-p N p O 4-s B s .

[0066] Specifically, the value of r can be, but is not limited to, 0.2, 0.4, 0.7, 0.9, 1.0, 1.3, 1.5, 1.7, 2.2, 2.5, 2.8, 3.2, 3.5, 3.7, 4.5, 4.8, 4.9, 5.1, 5.3, 5.5, 5.6, 5.8, 5.9, 6.0, etc.

[0067] Specifically, the value of p can be, but is not limited to, 0, 0.05, 0.09, 0.1, 0.15, 0.18, 0.22, 0.25, 0.28, 0.35, 0.39, 0.45, 0.48, 0.55, 0.59, 0.6, 0.65, 0.68, 0.7, 0.75, 0.79, 0.85, 0.88, 0.9, 0.94, and 0.99.

[0068] Specifically, the value of s may be, but is not limited to, 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09.

[0069] It can be understood that the product of the planar shrinkage rate α of the substrate and the mass fraction w3 of the lithium-supplementing particles can represent the total lithium release amount of the multiple lithium-supplementing particles in the positive electrode active layer 231; the larger the value of α×w3, the greater the total lithium release amount of the multiple lithium-supplementing particles; the smaller the value of α×w3, the smaller the total lithium release amount of the multiple lithium-supplementing particles.

[0070] In an embodiment of the present application, the lithium-supplementing particles include a matrix and a coating layer, wherein the coating layer is disposed on the periphery of the matrix. On one hand, the coating layer can coat and protect the matrix, preventing the matrix from reacting with air and being oxidized, ensuring that the lithium-supplementing particles can replenish lithium during charging of the battery 200, thereby improving the performance of the lithium-supplementing particles. On the other hand, the coating layer has conductive properties. When active ions in the matrix are deintercalated, they can enter the electrolyte 100 through the coating layer. The coating layer can reduce the impedance of the active ions deintercalating from the lithium-supplementing particles, thereby improving the rate performance of the battery 200. In this embodiment, when the battery 200 is charged, the lithium-replenishing particles can release lithium ions to replenish the lithium ions lost by the battery 200 during the initial charge and discharge and charge and discharge cycles. The electrolyte 100 contains a first additive, which can undergo oxidative decomposition better than other components in the electrolyte 100 to generate products that adhere to the surface of the lithium-replenishing particles, reducing the contact between the oxygen generated by the lithium-replenishing particles and the electrolyte 100. The products generated by the first additive can also form a film on the surface of the negative electrode plate 210, enhancing the strength of the interface film between the negative electrode plate 210 and the electrolyte 100, thereby slowing down the side reaction between the electrolyte 100 and oxygen, which is beneficial to maintaining the stability of the electrolyte 100, and thus making the battery 200 have a higher capacity retention rate. When the value of α×w3 / w1 satisfies the range of 0.4≤α×w3 / w1≤1.7, the total lithium release amount of the lithium-supplementing particles and the mass fraction of the first additive are both within a reasonable range. On the one hand, the total lithium release amount of the lithium-supplementing particles is within a reasonable range, and the lithium-supplementing particles can release lithium ions in a timely manner to replenish the lithium ions lost by the battery 200 during the charge and discharge cycle, so that the battery 200 has a higher initial efficiency. In addition, the first additive undergoes redox decomposition preferentially compared to other components in the electrolyte 100, and the amount of decomposition products generated is within a reasonable range. This can not only slow down the side reaction of oxygen released by lithium ions with the electrolyte 100, but also prevent excessive acid generated by the first additive from attacking the interface film between the positive electrode 230 and / or the negative electrode 210 and the electrolyte 100, so that the battery 200 has a higher capacity retention rate, safety performance, and energy efficiency. When the value of α×w3 / w1 is too large, the total lithium release amount of the lithium-supplementing particles is much greater than the mass fraction of the first additive. When the total lithium release amount of the lithium-supplementing particles is too large and the mass fraction of the first additive is too small, the lithium-supplementing particles release too many lithium ions, which easily leads to local lithium deposition on the negative electrode 210. In addition, the lithium-supplementing particles release too much oxygen while releasing lithium ions, and the first additive produces fewer products of redox decomposition, making it difficult to prevent the side reaction of the oxygen released by the lithium ions with the electrolyte 100. The stability of the electrolyte 100 is poor, which in turn leads to a low capacity retention rate of the battery 200.When the value of α×w3 / w1 is too small, the total lithium release amount of the lithium-supplementing particles is far less than the mass fraction of the first additive. On the one hand, when the total lithium-supplementing particles release too little lithium ions, the lithium-supplementing particles are unable to replenish the lithium ions lost by the battery 200 during the charge and discharge cycles. The lithium-supplementing particles are unable to fully replenish lithium ions in the battery 200, thereby reducing the initial efficiency of the battery 200. On the other hand, when the mass fraction of the first additive is too large, although the first additive can slow down the side reaction of the oxygen generated by the lithium-replenishing particles with the electrolyte 100, the product of the redox reaction of the first additive includes acid. Then, the acid generated by the first additive is excessive, which will attack the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby reducing the stability of the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby increasing the internal resistance of the battery 200, and then reducing the charge and discharge efficiency, energy efficiency and safety performance of the battery 200 when the electrolyte 100 is applied to the battery 200.

[0071] It can be understood that in the cross-section of the positive electrode sheet, the area defined by the inner contour of the coating layer is S1, and after the lithium-supplementing particles release lithium ions, the area defined by the outer contour of the matrix is ​​S2. Then the planar shrinkage rate α of the matrix satisfies the relationship: α = (S1-S2) / S1×100%.

[0072] It can be understood that the cross section of the positive electrode sheet 230 is obtained by cutting the positive electrode sheet 230 using an ion beam milling (CP) instrument.

[0073] In this embodiment, during the lithium-ion release process of the lithium-supplementing particle, the matrix shrinks due to a decrease in lithium content, while the shape of the coating layer remains unchanged. In this embodiment, the area S1 defined by the inner contour of the coating layer represents the area of ​​the matrix before shrinkage, and the area S2 defined by the outer contour of the matrix represents the area after shrinkage. The difference between S1 and S2 represents the area of ​​the matrix contracted during the shrinkage process. The planar shrinkage rate of the matrix can be used to characterize the amount of lithium released by a single lithium-supplementing particle during the lithium-supplementing process.

[0074] In some embodiments, the battery 200 satisfies the relationship: 20≤α / w1≤60.

[0075] Specifically, the value of α / w1 can be, but is not limited to, 20, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 55, 57, 58, and 60.

[0076] In this embodiment, when the battery 200 satisfies the relationship: 20≤α / w1≤60, the ratio of the planar shrinkage of the substrate to the mass fraction w1 of the first additive is within a reasonable range. When the battery 200 is charged, the lithium-supplementing particles release an appropriate amount of lithium ions to replenish the lithium ions lost during the charge-discharge cycle of the battery 200, and the oxygen released by the lithium-supplementing particles is also within a reasonable range. The first additive in the electrolyte 100 preferentially undergoes an oxidation reaction, and the resulting product adheres to the surface of the lithium-supplementing particles, preventing side reactions between the electrolyte 100 and oxygen. The product generated by the first additive also forms a film on the surface of the negative electrode plate 210, enhancing the strength of the interfacial film between the negative electrode plate 210 and the electrolyte 100, thereby improving the stability of the electrolyte 100. When the value of α / w1 is too large, the planar shrinkage rate of the substrate is too large, and the lithium-supplementing particles release too many lithium ions, which easily leads to local lithium deposition on the negative electrode sheet 210. In addition, the lithium-supplementing particles release too much oxygen, and the first additive cannot prevent the side reaction between the electrolyte 100 and oxygen, thereby reducing the stability of the electrolyte 100 and further reducing the capacity retention rate of the battery 200. When the value of α / w1 is too small, the planar shrinkage of the matrix is ​​too small or the mass fraction of the first additive is too large, making it difficult for the lithium-replenishing particles to replenish the lithium ions lost by the battery 200 during the charging and discharging process, and the first additive generates too much acid during the redox reaction. The acid generated by the first additive will attack the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, reducing the stability of the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby increasing the internal resistance of the battery 200, and subsequently reducing the charging and discharging efficiency, energy efficiency and safety performance of the battery 200 when the electrolyte 100 is applied to the battery 200.

[0077] Alternatively, in some embodiments, the chemical formula of the matrix is: Li 1+r FeO4, where r ranges from: 3.5 <r<4.5。

[0078] Specifically, the value of r can be, but is not limited to, 3.52, 3.54, 3.56, 3.6, 3.62, 3.64, 3.65, 3.68, 3.69, 3.7, 3.72, 3.74, 3.78, 3.8, 3.82, 3.84, 3.86, 3.88, 3.89, 3.9, 4, 4.1, 4.15, 4.2, 4.24, 4.28, 4.3, 4.36, 4.38, 4.4, 4.42, 4.44, 4.45, 4.47, 4.49, and 4.5. Optionally, the matrix includes Li5FeO4.

[0079] Understandably, the value of r is affected by the preparation process and synthesis technology of the lithium supplement particles.

[0080] In this embodiment, the matrix includes Li r FeO4. The element composition of the matrix is simple, the material price is low, and the synthesis process is simple, which is beneficial to simplify the preparation process of the positive electrode sheet 230 and save the preparation cost of the positive electrode sheet 230. In this embodiment, the matrix includes Li r FeO4, and r satisfies the range 3.5 < r < 4.5, so that the matrix has a high lithium content. When the positive electrode sheet 230 is applied to the battery 200 and the battery 200 is charged, the matrix can release more lithium ions in time to supplement the lithium ions lost in the charge-discharge cycle of the battery 200, so as to improve the first efficiency and energy density of the battery 200.

[0081] Optionally, the coating layer is a carbon coating layer. The coating layer has conductivity and can protect the matrix it wraps to improve the antioxidant performance of the lithium supplement particles.

[0082] Optionally, the chemical formula of the coating layer is: Z x O y @C, where Z is selected from at least one of iron, cobalt, nickel, titanium, zinc, magnesium, aluminum, manganese, vanadium, chromium, zirconium, copper, niobium, tantalum, tungsten, yttrium and lanthanum, and the type of Z is the same as the type of M in the matrix. The coating layer also satisfies the relationship: 1 ≤ x ≤ 3, 1 ≤ y ≤ 5.

[0083] Understandably, the chemical formula of the lithium supplement particles is Li 1+r M 1-p N p O 4-s B s @Z x O y @C. Then the lithium supplement particles are formed by Li 1+r M 1-p N p O 4-s B s 、M x O y and C. The lithium supplement particles take Li 1+r M 1-p N p O 4-s B<r<4.5,使得所述基体具有较高的含锂量,使得当所述正极极片230应用于电池200且对所述电池200进行充电时,所述基体可及时释放出较多的锂离子,以及时补充电池200在充放电循环中损耗的锂离子,使得对所述电池200的首效及能量密度进行提升。 s x O y as the core, and wrap M x O yThe oxide layer protects the core from external oxidation and corrosion. Carbon is then coated around the oxide layer to form a carbon layer, which improves the conductivity of the coating. In other words, the coating comprises an oxide layer and a carbon layer, disposed sequentially, with the oxide layer disposed between the carbon layer and the substrate.

[0084] Specifically, the value of x can be, but is not limited to, 1, 1.2, 1.3, 1.5, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.4, 2.6, 2.7, 2.8, 2.9, and 3.

[0085] Specifically, the value of y can be, but is not limited to, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.5, 2.7, 2.8, 2.9, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.1, 4.3, 4.5, 4.6, 4.7, 4.9 and 5, etc.

[0086] In this embodiment, the chemical formula of the coating layer is Z x O y @C, the coating layer is composed of an oxide layer and a carbon layer, and the oxide layer is arranged closer to the substrate than the carbon layer. The oxide layer can be used to protect the substrate to prevent the substrate from being oxidized by oxygen in the air, thereby ensuring the substrate releases lithium ions to replenish lithium for the battery 200. In addition, the type of Z is the same as the type of M in the matrix, which can avoid the introduction of too many heteroatoms, thereby facilitating the improvement of the uniformity of the lithium-replenishing particles. Furthermore, the coating layer also includes carbon, which is coated on the periphery of the oxide layer to form a carbon layer, which is beneficial to improving the conductive properties of the lithium-replenishing particles and reducing the impedance of active ions entering the electrolyte 100 from the substrate and the coating layer, thereby facilitating the improvement of the energy efficiency of the battery 200.

[0087] In some embodiments, the plane shrinkage ratio α of the substrate is in the range of 5%≤α≤40%.

[0088] Specifically, the value of α can be but is not limited to 5%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 27%, 29%, 30%, 31%, 34%, 35%, 37%, 38%, 39% and 40%, etc.

[0089] In this embodiment, when the planar shrinkage rate α of the substrate satisfies the range of 5%≤α≤40%, the value of the planar shrinkage rate α of the substrate is within a reasonable range. During the charging process of the battery 200, the amount of lithium ions released by the lithium-replenishing particles is within a reasonable range, so that the lithium-replenishing particles can not only replenish the active ions lost in the charge and discharge cycle of the battery 200, but also avoid reducing the stability of the electrolyte 100 due to excessive oxygen release, thereby enabling the battery 200 to have higher initial efficiency, energy density and capacity retention rate. When the planar shrinkage rate α of the substrate is too large, during the charging process of the battery 200, the lithium-supplementing particles release too many lithium ions, which can easily lead to local lithium deposition on the negative electrode 210. At the same time, the lithium-supplementing particles release too many oxygen anions and iron ions. The oxygen anions combine with the iron ions to generate oxygen, which causes the lithium-supplementing particles to release too much oxygen, creating a safety hazard and shortening the service life of the battery 200. In addition, the electrolyte 100 reacts with oxygen to form side reactions, which can lead to poor stability of the electrolyte 100. The products produced by the side reactions of the electrolyte 100 with oxygen may increase the internal resistance of the battery 200, thereby reducing the capacity retention rate and energy efficiency of the battery 200. When the planar shrinkage rate α of the substrate is too small, during the charging process of the battery 200, the lithium-supplementing particles release too few lithium ions. The lithium-supplementing particles are unable to replenish the active ions lost by the battery 200 during the charge and discharge cycle, which in turn causes the active ions in the battery 200 to continue to decrease, thereby reducing the initial efficiency, energy efficiency, and energy density of the battery 200.

[0090] Preferably, the plane shrinkage ratio α of the substrate is in the range of 10%≤α≤30%. Specifically, the plane shrinkage ratio α of the substrate can be, but is not limited to, 10%, 12%, 14%, 15%, 18%, 20%, 21%, 23%, 25%, 26%, 27%, 28%, and 30%.

[0091] In this embodiment, when the planar shrinkage rate α of the substrate satisfies the range of 10%≤α≤30%, the value of the planar shrinkage rate α of the substrate is within the preferred range. During the charging process of the battery 200, the amount of lithium ions released by the lithium-replenishing particles is within a more reasonable range, so that the lithium-replenishing particles can not only replenish the active ions lost by the battery 200 during the charge and discharge cycle, but also avoid reducing the stability of the electrolyte 100 due to excessive oxygen release, thereby enabling the battery 200 to have higher initial efficiency, energy density and capacity retention rate.

[0092] Optionally, the highest charging voltage of the battery 200 can be controlled to control the planar shrinkage rate α of the substrate; the greater the highest charging voltage of the battery 200, the more lithium ions released by the substrate, and the greater the planar shrinkage rate of the substrate; the smaller the highest charging voltage of the battery 200, the fewer lithium ions released by the substrate, and the smaller the planar shrinkage rate of the substrate; wherein, the highest charging voltage of the battery 200 is U, then U satisfies the range: 3.85V≤U≤4.2V.

[0093] Specifically, the value of the maximum charging voltage U formed for the battery 200 can be, but is not limited to, 3.85V, 3.86V, 3.88V, 3.89V, 3.9V, 3.92V, 3.93V, 3.94V, 3.96V, 3.98V, 3.99V, 4.0V, 4.02V, 4.05V, 4.08V, 4.1V, 4.12V, 4.13V, 4.15V, 4.16V, 4.18V, 4.19V and 4.2V, etc.

[0094] It is understandable that, in the terminology of this application, "formation" refers to the process of charging the battery 200 for the first time, also known as initial charging or forming. In this process, the positive electrode material layer and the negative electrode material layer of the battery 200 are charged and form an electrochemical reaction, so that the chemical reaction system inside the battery 200 reaches a stable state, forming a solid electrolyte interface (SEI) film, that is, the interface film between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby ensuring that the battery 200 has better performance in subsequent use.

[0095] In this embodiment, when the charging voltage U for charging the battery 200 satisfies the range of 3.85V≤U≤4.2V, the highest charging voltage formed for the battery 200 is within a reasonable range, so that the planar shrinkage rate of the substrate is within a reasonable range. Then, when the positive electrode plate 230 is applied to the battery 200 and the battery 200 is charged, the lithium release amount of the substrate is within a suitable range. The lithium ions released from the substrate can be embedded in the negative electrode plate 210 through the electrolyte 100 to supplement the lithium ions lost due to the formation of the SEI film, thereby improving the initial efficiency of the battery 200, improving the energy density and capacity retention rate of the battery 200, and also helping to extend the cycle life of the battery 200. When the value of the highest charging voltage U formed for the battery 200 is too large, the planar shrinkage rate of the substrate is too large. Then, when the positive electrode plate 230 is applied to the battery 200 and the battery 200 is charged, the substrate releases too much lithium, so that when the lithium ions move to the negative electrode plate 210, due to the limitation of the negative electrode dynamics, they cannot all be quickly embedded in the negative electrode, so that some of the lithium ions are precipitated on the surface of the negative electrode plate 210, causing lithium deposition on the surface of the negative electrode plate 210. In addition, the substrate releases oxygen while releasing lithium ions, and the amount of oxygen released in this process is also too large, thereby causing safety hazards, shortening the cycle life of the battery 200 and reducing the safety performance of the battery 200. When the value of the maximum charging voltage U formed for the battery 200 is too small, the planar shrinkage rate of the substrate is too small. Then, when the positive electrode plate 230 is applied to the battery 200 and the battery 200 is charged, the amount of lithium released by the substrate is too small, which reduces the utilization rate of the lithium-replenishing particles. In addition, the lithium ions released by the substrate are difficult to replenish the lithium ions lost due to the formation of the SEI film, so that when the positive electrode plate 230 is applied to the battery 200, the first efficiency, energy density and capacity retention rate of the battery 200 are all low, and the lithium-replenishing particles are difficult to play the role of replenishing lithium ions to the battery 200.

[0096] In some embodiments, in the positive electrode active layer 231 , the mass fraction w3 of the lithium supplement particles is in the range of: 0.5%≤w3≤5%.

[0097] It can be understood that in the positive electrode active layer 231 , the mass fraction w3 of the lithium-supplementing particles may be the ratio of the mass of the lithium-supplementing particles to the mass of the positive electrode active layer 231 .

[0098] Specifically, the value of w3 can be but is not limited to 0.5%, 0.6%, 0.7%, 0.9%, 1%, 1.1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.2%, 3.4%, 3.5%, 3.7%, 3.9%, 4.0%, 4.1%, 4.3%, 4.5%, 4.6%, 4.7%, 4.9% and 5%, etc.

[0099] In this embodiment, when the mass fraction w3 of the lithium-replenishing particles satisfies the range of 0.5% ≤ w3 ≤ 5%, the mass fraction of the lithium-replenishing particles is within a reasonable range. During the charging process of the battery 200, the amount of lithium ions released by the lithium-replenishing particles is within a reasonable range. This allows the lithium-replenishing particles to replenish the active ions lost in the charge and discharge cycles of the battery 200 while avoiding the reduction in the stability of the electrolyte 100 due to excessive oxygen release, thereby enabling the battery 200 to have high initial efficiency, energy density, and capacity retention. When the mass fraction w3 of the lithium-supplementing particles is too large, the mass content of the lithium-supplementing particles in the positive electrode active layer 231 is too high. During the charging process of the battery 200, the lithium-supplementing particles may release excessive lithium ions, oxygen anions, and iron ions. The oxygen anions combine with the iron ions to generate oxygen, causing the lithium-supplementing particles to release excessive oxygen, creating a safety hazard and shortening the service life of the battery 200. In addition, the electrolyte 100 and oxygen react with the side reaction, which will cause the electrolyte 100 to have poor stability, thereby reducing the capacity retention rate of the battery 200. When the mass fraction w3 of the lithium-supplementing particles is too small, the mass fraction of the lithium-supplementing particles in the positive electrode active layer 231 is too small. During the charging process of the battery 200, the lithium-supplementing particles can release too few lithium ions. The lithium-supplementing particles are unable to replenish the active ions lost by the battery 200 during the charge and discharge cycle, thereby reducing the initial efficiency and energy density of the battery 200.

[0100] In some embodiments, at a magnification of 5K, within a rectangular area of ​​22 μm × 15 μm, in the cross section of the positive electrode sheet 230, the number of the lithium supplement particles is multiple; the sum of the areas defined by the inner contours of the multiple coating layers is S3, and after the lithium supplement particles release lithium ions, the sum of the areas defined by the outer contours of the multiple substrates is S4. Then, the shrinkage area S of the multiple lithium supplement particles during the lithium supplement process satisfies the relationship: S = S3-S4, and S satisfies the range: 1.5 μm 2 ≤S / w1≤8μm 2 .

[0101] Specifically, the value of S / w1 may be, but is not limited to, 1.5 μm. 2 , 1.8μm 2 , 2μm 2 , 2.2μm 2 , 2.5μm 2 , 2.8μm 2 , 3μm 2 , 3.2μm 2 , 3.5μm 2 , 4μm 2 , 4.5μm 2 , 4.8μm 2 , 5μm 2 , 5.2μm 2 , 5.6μm 2 , 6μm 2 , 6.5μm 2 , 7μm 2 , 7.5μm 2 and 8μm 2 wait.

[0102] It can be understood that the rectangular area of ​​22 μm×15 μm is a rectangular area with a length of 22 μm and a width of 15 μm.

[0103] In this embodiment, at a specific magnification and in a specific area, the sum of the areas defined by the inner contours of the multiple coating layers S3 is the sum of the areas of the matrix of the multiple lithium supplement particles before shrinkage, and the sum of the areas defined by the outer contours of the multiple matrixes S4 is the sum of the areas of the matrix of the multiple lithium supplement particles after shrinkage. The difference between S3 and S4 is the shrinkage area S of the multiple lithium supplement particles during the lithium supplement process. When S / w1 satisfies the range of 1.5μm 2 ≤S / w1≤8μm 2When the value of S / w1 is within a reasonable range, the amount of lithium ions released by the multiple lithium-replenishing particles is within a reasonable range, so that the shrinkage area of ​​the multiple lithium-replenishing particles is within a reasonable range, and the lithium ions lost by the battery 200 during the charge and discharge process are replenished in time, so that the battery 200 has a higher first efficiency, energy density and capacity retention rate. In addition, the borate additive is within a reasonable range, so that the borate additive can be combined with the oxygen anions released by the lithium-replenishing particles in time to avoid the generation of a large amount of oxygen and side reactions with the electrolyte 100. It can also avoid the excessive borate additive and increase the interface impedance between the positive electrode sheet 230 / negative electrode sheet 210 and the electrolyte 100, ultimately making the battery 200 have higher cycle performance, safety performance and energy efficiency. When the value of S / w1 is too large, the shrinkage area of ​​the multiple lithium-replenishing particles during the lithium-replenishing process is too large or the mass fraction of the borate additive is too small. During the charging process of the battery 200, the multiple lithium-replenishing particles release too many lithium ions, which can easily lead to local lithium deposition on the negative electrode 210, increasing the internal resistance of the battery 200, thereby reducing the energy efficiency of the battery 200. At the same time, the lithium-replenishing particles will release too many oxygen anions and iron ions. The borate additive can only combine with a small number of oxygen anions, and then the oxygen anions combine with the iron ions to generate more oxygen, creating a safety hazard and shortening the service life of the battery 200. When the value of S / w1 is too small, the shrinkage area of ​​the multiple lithium-replenishing particles during the lithium replenishment process is too small or the mass fraction of the borate additive is too large. The multiple lithium-replenishing particles release too few lithium ions, and the multiple lithium-replenishing particles are difficult to replenish the active ions lost by the battery 200 during the charge and discharge cycle, thereby reducing the initial efficiency and energy density of the battery 200. In addition, when the mass fraction of the borate additive is too large, in the electrolyte 100, part of the borate additive combines with oxygen anions, and excess borate additives may adhere to the interface between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, and undergo a reduction reaction and generate decomposition products, thereby increasing the interface impedance, and then reducing the transmission speed and migration speed of active ions between the positive electrode plate 230 / negative electrode plate 210 and the electrolyte 100, thereby making the energy efficiency of the battery 200 low.

[0104] In some embodiments, the shrinkage area S of the plurality of lithium supplement particles during the lithium supplement process is in the range of: 0.1 μm 2 ≤S≤6μm 2 .

[0105] Specifically, the value of S may be, but is not limited to, 0.1 μm. 2 , 0.5μm 2 , 0.8μm 2 , 1μm 2, 1.2μm 2 , 1.5μm 2 , 2μm 2 , 2.2μm 2 , 2.5μm 2 , 3μm 2 , 3.2μm 2 , 3.5μm 2 , 3.8μm 2 , 4μm 2 , 4.5μm 2 , 4.8μm 2 , 5μm 2 , 5.2μm 2 , 5.6μm 2 , 5.8μm 2 and 6μm 2 wait.

[0106] In this embodiment, when the shrinkage area S of the plurality of lithium supplement particles during the lithium supplement process satisfies the range of 0.1 μm 2 ≤S≤6μm 2 When the lithium ions released by the multiple lithium-replenishing particles during the lithium-replenishing process are within a reasonable range and are replenished to the electrolyte 100, and are replenished to the negative electrode plate 210 through the electrolyte 100, so as to timely replenish the active ions lost by the battery 200 during the charge and discharge cycle, thereby improving the first efficiency, energy density and capacity retention rate of the battery 200. When the value of the shrinkage area S of the multiple lithium-replenishing particles during the lithium-replenishing process is too large, then during the charging of the battery 200, the multiple lithium-replenishing particles release too many lithium ions during the lithium-replenishing process, which can easily lead to local lithium deposition on the negative electrode plate 210, increase the internal resistance of the battery 200, and thus reduce the energy efficiency of the battery 200. At the same time, the lithium-replenishing particles will release too many oxygen anions and iron ions. The oxygen anions combine with the iron ions to generate oxygen, which creates a safety hazard and shortens the service life of the battery 200. When the shrinkage area S of the plurality of lithium-replenishing particles during the lithium-replenishing process is too small, the lithium-replenishing particles release too few lithium ions during the lithium-replenishing process, and the lithium-replenishing particles are unable to replenish the active ions lost by the battery 200 during the charge and discharge cycles, thereby reducing the initial efficiency and energy density of the battery 200.

[0107] The technical solution of this application is further described below with multiple embodiments.

[0108] Examples 1 to 9, Comparative Examples 1 to 9:

[0109] 1. Preparation of positive electrode sheet 230:

[0110] The positive electrode active material (for example, lithium iron phosphate), lithium supplement particles (for example, Li5FeO4 as a matrix, the chemical formula of the coating layer is Al2O3@C or Li6CoO4 as a matrix, the coating layer is a carbon coating layer), a positive electrode conductive agent (for example, conductive carbon black), and a positive electrode binder (for example, polyvinylidene fluoride) are dispersed in a solvent N-methylpyrrolidone and mixed uniformly to obtain a positive electrode slurry. In the positive electrode slurry, the mass fraction of the positive electrode active material: the mass fraction of the positive electrode conductive agent: the mass fraction of the positive electrode binder is 96%: 0.5%: 2.3%. The positive electrode slurry is coated on the positive electrode current collector layer 232 (for example, aluminum foil). The positive electrode slurry unit area (1540.25mm 2 ) with a coating weight of 254 mg to form a positive electrode active layer 231. After drying, cold pressing, slitting, and cutting, the positive electrode sheets 230 of Examples 1 to 9 and Comparative Examples 1 to 9 were obtained. The lithium-supplementing particles of Examples 1 to 8 and Comparative Examples 1 to 9 used Li₅FeO₄ as the matrix and the coating layer had the chemical formula of Al₂O₃@C. The lithium-supplementing particles of Example 9 used Li₆CoO₄ as the matrix and the coating layer was a carbon coating layer. The values ​​of the mass fraction w₃ of the lithium-supplementing particles, the planar shrinkage rate α of the matrix, and the shrinkage area S of the multiple lithium-supplementing particles during the lithium-supplementing process for Examples 1 to 9 and Comparative Examples 1 to 9 are shown in Table 1.

[0111] 2. Preparation of negative electrode sheet 210 and separator 220:

[0112] The negative electrode active material (for example, artificial graphite), the negative electrode conductive agent (for example, conductive carbon black), the negative electrode thickener (for example, carboxymethyl cellulose) and the negative electrode binder (for example, styrene-butadiene rubber) are dispersed in deionized water at a mass ratio of 96.5:0.5:1:2 and mixed evenly to obtain a negative electrode slurry. The negative electrode slurry is coated on the negative electrode current collector layer (for example, copper foil). The coating weight of the negative electrode slurry per unit area (1540.25 mm2) is 122 mg. After drying, cold pressing, slitting and cutting, the negative electrode sheets 210 of Examples 1 to 9 and Comparative Examples 1 to 9 are obtained.

[0113] A polyethylene diaphragm with a thickness of 16 μm was selected.

[0114] 3. Preparation of electrolyte 100:

[0115] In an argon atmosphere glove box with a moisture content of ≤1 ppm, ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were mixed in a mass ratio of 1:1:1. Dried lithium electrolyte salt, lithium hexafluorophosphate, was then dissolved in a solvent and stirred until completely dissolved. A first additive and a second additive were added and mixed uniformly to obtain an electrolyte solution 100. The lithium salt concentration was 1 mol / L. In the electrolyte solutions 100 of Examples 1 to 9 and Comparative Examples 1 to 9, the mass fraction w1 of the first additive and the mass fraction w2 of the second additive are shown in Table 1.

[0116] 4. Assembly of battery 200:

[0117] The positive electrode sheets 230, separators 220 and negative electrode sheets 210 of Examples 1 to 9 and Comparative Examples 1 to 9 prepared above are stacked in sequence, with the separator 220 located between the positive electrode sheet 230 and the negative electrode sheet 210, and then wound to obtain a bare cell. The bare cell is placed in an outer package, dried, and injected with the above-mentioned electrolyte 100. After standing, forming, and packaging, implementing cells 1 to 6 and comparative cells 1 to 9 are obtained, wherein the positive electrode sheet 230 of Example 1 and the electrolyte 100 of Example 1 are arranged in implementing cell 1, the positive electrode sheet 230 of Example 2 and the electrolyte 100 of Example 2 are arranged in implementing cell 2, the positive electrode sheet 230 of comparative cell 1 and the electrolyte 100 of comparative cell 1 are arranged in comparative cell 1, and so on.

[0118] The test method for the plane shrinkage rate α of the substrate in the positive electrode sheet 230 is as follows:

[0119] Referring to Figures 3 and 4, the positive electrode sheet 230 is assembled into the battery 200 and the battery 200 is charged. The positive electrode sheet 230 is disassembled and cut using an ion beam milling (CP) instrument to obtain a cross-section of the positive electrode sheet 230. The positive electrode sheet 230 is observed using a scanning electron microscope (SEM) and photographed at a magnification of 10K. Figure 3 is a scanning electron microscope image of the lithium-supplementing particles after shrinkage according to an embodiment of the present application. Figure 3 shows the situation of taking points along the inner contour of the coating layer. Using image analysis software and a polygon measurement function, points are taken along the inner contour of the coating layer. The image analysis software is used to calculate the area S1 defined by the inner contour of the coating layer. The area defined by the inner contour of the coating layer is the area of ​​the substrate before shrinkage. Figure 4 is a scanning electron microscope image of a lithium-supplemented particle after shrinkage, according to another embodiment of the present application. Figure 4 illustrates the situation of selecting points along the outer contour of the substrate. Using image analysis software, the area S2 defined by the outer contour of the substrate is calculated. The area defined by the outer contour of the substrate is the area of ​​the substrate after shrinkage. The in-plane shrinkage rate α of the substrate satisfies the equation: α = (S1 - S2) / S1 × 100%. The in-plane shrinkage rate α of the substrate is controlled by controlling the maximum voltage of the lithium-ion battery 200.

[0120] The test method for the shrinkage area S of the plurality of substrates in the positive electrode sheet 230 during the lithium replenishment process is as follows:

[0121] The positive electrode sheet 230 was assembled into the battery 200 and charged. The positive electrode sheet 230 was then disassembled and cut using an ion beam milling (CP) instrument to obtain a cross-section of the positive electrode sheet 230. The positive electrode sheet 230 was observed using a scanning electron microscope (SEM) and photographed at a magnification of 5K. Within a rectangular area measuring 22 μm × 15 μm, the sum of the areas defined by the inner contours of the multiple coating layers is S3, which is the total area of ​​the multiple lithium-replenishing particles before shrinkage. The sum of the areas defined by the outer contours of the multiple substrates is S4, which is the total area of ​​the multiple lithium-replenishing particles after shrinkage. Therefore, the shrinkage area S of the multiple substrates during the lithium replenishment process = S3 - S4.

[0122] Table 1 below shows the structural parameters of the electrolyte 100 and the battery 200 of Examples 1 to 9 and Comparative Examples 1 to 9.

[0123] Table 1: Structural parameters of the electrolyte 100 and the battery 200 of Examples 1 to 9 and Comparative Examples 1 to 9.

[0124] Performance test of battery 200:

[0125] The implementation batteries 1 to 9 and the comparative batteries 1 to 9 were placed at 25°C for 1 hour, charged to 3.65V at 0.5P, and then discharged to 2.5V at 0.5P. The initial discharge capacity C1 of the battery 200 was recorded, and the initial discharge energy was E1. The implementation batteries 1 to 9 and the comparative batteries 1 to 9 were cycled for 500 cycles, and the discharge capacity C 500 and charging capacity C' 500 , discharge energy E 800 and charging energy E' 800 The energy efficiency of the 500 cycles of the implementation batteries 1 to 9 and the comparison batteries 1 to 9 is E=E 500 / E' 500 × 100%, and the capacity retention rate Cf after 500 cycles of the implementation batteries 1 to 9 and the comparative batteries 1 to 9 is obtained. 500 The energy efficiency E and capacity retention rate Cf of the embodiment batteries 1 to 9 and the comparative batteries 1 to 9 after 500 cycles are shown in Table 2.

[0126] Table 2 below shows the performance parameters of implementation batteries 1 to implementation batteries 9 and comparison batteries 1 to comparison batteries 9.

[0127] Table 2: Performance parameters of Example Batteries 1 to 9 and Comparative Batteries 1 to 9.

[0128] Referring to Tables 1 and 2, the data from Examples 1 to 3 and Comparative Example 1 show that the values ​​of the planar shrinkage rate α of the substrate, the shrinkage area S of the multiple lithium-supplementing particles during the lithium-supplementing process, the mass fraction w2 of the second additive, the mass fraction w1 of the first additive, w2 / w1, and S / w1 in Examples 1 to 3 and Comparative Example 1 are all within reasonable ranges. In Examples 1 to 3, the values ​​of α / w1 and S / w1 are also within reasonable ranges. However, in Comparative Example 1, the value of α / w1 is less than 20, and the value of α×w3 / w1 is less than 0.4, resulting in the energy efficiency of Comparative Cell 1 being lower than that of Example Cells 1 to 3. This is because, in Comparative Example 1, the total lithium release amount of the substrate is too small or the mass fraction of the first additive is too large. When the total lithium release amount of the matrix is ​​too low, the mass fraction of the lithium-supplementing particles is too low, or the lithium ions released by the lithium-supplementing particles are too few, making it difficult for the lithium-supplementing particles to replenish the lithium ions lost during the charge-discharge cycle of the battery 200. The lithium-supplementing particles are unable to fully perform their function of replenishing lithium ions to the battery 200, thereby reducing the initial efficiency of the battery 200. When the mass fraction of the first additive is too high, although the first additive can slow down the side reaction between the oxygen generated by the lithium-supplementing particles and the electrolyte 100, the products of the redox reaction of the first additive include acid. The excessive acid produced by the first additive will attack the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby reducing the stability of the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, increasing the internal resistance of the battery 200, and subsequently reducing the charge-discharge efficiency, energy efficiency, and safety performance of the battery 200 when the electrolyte 100 is used in the battery 200.

[0129] It can be seen from the data of Example 4, Comparative Example 4 and Comparative Example 5 that the values ​​of the planar shrinkage rate α of the substrate, the mass fraction w1 of the first additive and the value of α / w1 in Example 4, Comparative Example 4 and Comparative Example 5 are all within a reasonable range. The value of the mass fraction w2 of the second type of additive in Example 4 satisfies the range of 1%≤w2≤4%, so that w2 / w1 is within a reasonable range; the value of the mass fraction w2 of the second type of additive in Comparative Example 4 is less than 1%, so that the value of w2 / w1 is too small; the value of the mass fraction w2 of the second type of additive in Comparative Example 5 is greater than 4%, so that the value of w2 / w1 is too large, which makes the capacity retention rate of the implementation battery 4 after 500 cycles higher than the capacity retention rate of the comparison battery 4 and the comparison battery 5 after 500 cycles, and the energy efficiency of the implementation battery 4 after 500 cycles is higher than the energy efficiency of the comparison battery 5 after 500 cycles. This is because: in the embodiment of battery 4, the mass fraction of the first additive and the mass fraction of the second additive are both within a reasonable range. The first additive can not only produce enough decomposition products to cover the surface of the lithium-supplementing particles and slow down the reaction of the oxygen generated by the lithium-supplementing particles with the electrolyte 100, but also avoid the production of excessive acid due to an excessive amount of the first additive, and also avoid the consumption of the second additive due to an insufficient amount of the first additive, resulting in a waste of the second additive. Ultimately, the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100 has good stability, and the electrolyte 100 has good stability, so that the embodiment of battery 4 has both high energy efficiency and capacity retention. In the comparative battery 4, the mass fraction of the first additive is much greater than the mass fraction of the second additive. If the mass fraction of the second additive is too low, it will be difficult for the second additive to promote the formation of an interfacial film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, and to maintain the stability of the interfacial film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100. This may increase the internal resistance of the battery 200, thereby reducing the energy efficiency of the battery 200. In Comparative Battery 5, the mass fraction of the first additive is much smaller than the mass fraction of the second additive. If the mass fraction of the second additive is too high, when the battery 200 is charged, the first additive preferentially undergoes redox decomposition and is completely consumed, while some of the second additive still undergoes redox decomposition and produces gas, resulting in waste of the second additive. The gas generated by the second additive is not conducive to the circulation of the battery 200, and may increase side reactions between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, reducing the stability of the electrolyte 100, thereby increasing the internal resistance of the battery 200 and causing a low capacity retention rate of the battery 200.

[0130] The data from Examples 4, 7, and 8 show that, with other conditions remaining unchanged, as the mass fraction w3 of the lithium-supplementing particles increases, the value of α×w3 / w1 also increases, and the value of the contraction area S of the multiple lithium-supplementing particles during the lithium-supplementing process and the value of S / w1 also increase. This results in a gradual increase in the capacity retention rate and a gradual decrease in the energy efficiency of Battery 7, Battery 4, and Battery 8 after 500 cycles. This is because: the greater the mass fraction of the lithium-supplementing particles, the greater the value of the contraction area S of the multiple lithium-supplementing particles during the lithium-supplementing process, and the greater the value of α×w3 / w1 and S / w1, indicating that the total amount of lithium released by the lithium-supplementing particles increases. When charging the battery 200, the lithium-supplementing particles can promptly release lithium ions to replenish the lithium ions lost by the battery 200 during the charge and discharge cycles, resulting in a higher initial efficiency of the battery 200. As the amount of lithium released by the lithium-supplementing particles continues to increase, the lithium-supplementing particles release more and more oxygen, causing local lithium deposition on the negative electrode 210, and increasing the side reactions between oxygen and the electrolyte 100, increasing the internal resistance of the battery 200, thereby reducing the energy efficiency of the battery 200.

[0131] The data from Examples 4 and 9 show that the structural parameters of the electrolyte 100 and battery 200 in Examples 4 and 9 are identical, but the materials of the lithium-supplementing particles in Examples 4 and 9 are different. The lithium-supplementing particles in Example 4 use a Li₅FeO₄ matrix and a coating layer with the chemical formula of Al₂O₃@C, while the lithium-supplementing particles in Example 17 use a Li₆CoO₄ matrix and a carbon coating layer. The data in Table 2 show that both Battery 4 and Battery 9 exhibit high 500-cycle energy efficiency and 500-cycle capacity retention. Therefore, the lithium-supplementing particles used in Battery 200 exhibit good lithium-supplementing effects, and the borate additive can be combined with lithium-supplementing particles made of different materials to maintain the cycling performance of Battery 200.

[0132] From the data of Example 5, Comparative Example 6, and Comparative Example 7, it can be seen that the values ​​of the plane shrinkage rate α of the substrate, the mass fraction w2 of the second additive, and the shrinkage area S of the plurality of lithium replenishing particles during the lithium replenishing process in Examples 5, 6, and 7 are equal. The mass fraction w1 of the first additive in Example 5 satisfies the range of 0.01%≤w1≤2%. The values ​​of w2 / w1, α / w1, α×w3 / w1, and S / w1 are all within a reasonable range; the value of the mass fraction w1 of the first additive in Comparative Example 6 is less than 0.01%, which makes the values ​​of w2 / w1, α / w1, α×w3 / w1, and S / w1 too large; the value of the mass fraction w1 of the first additive in Comparative Example 7 is greater than 2%, which makes the values ​​of w2 / w1, α / w1, α×w3 / w1, and S / w1 too small, which makes the capacity retention rate of the implementation battery 5 after 500 cycles higher than the capacity retention rate of the comparison battery 6 and the comparison battery 7 after 500 cycles, and the energy efficiency of the implementation battery 5 after 500 cycles is higher than the energy efficiency of the comparison battery 6 and the comparison battery 7 after 500 cycles. This is because: in the embodiment of battery 5, the planar shrinkage rate α of the substrate, the mass fraction w1 of the first additive and the mass fraction w2 of the second additive are all within a reasonable range and restrict each other. The lithium-supplementing particles do not release too much oxygen while releasing lithium ions. The products generated by the redox decomposition of the first additive can effectively block the side reaction between the electrolyte 100 and oxygen, and the acid generated by the first additive is not excessive, which can also prevent the second additive from being oxidized and decomposed, so that the second additive can maintain the interface stability between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby making the embodiment of battery 5 have both high capacity retention and energy efficiency. In comparative battery 6, however, the mass fraction w1 of the first additive is too small, resulting in excessive values ​​of w2 / w1 and α / w1. On the one hand, the shrinkage rate of the matrix is ​​too large and the mass fraction of the first additive is too small. The lithium-supplementing particles release too many lithium ions, which easily leads to local lithium deposition on the negative electrode 210. Furthermore, the lithium-supplementing particles release too much oxygen while releasing lithium ions, and the first additive produces fewer products of redox decomposition, making it difficult to prevent the side reaction of the oxygen released by the lithium ions with the electrolyte 100. The stability of the electrolyte 100 is poor, which results in a lower capacity retention rate for comparative battery 6.On the other hand, if the mass fraction of the second additive is too large compared to the mass fraction of the first additive, when the battery 200 is charged, the first additive undergoes preferential redox decomposition and is consumed, but part of the second additive still undergoes redox decomposition to produce gas, resulting in a waste of the second additive. The gas produced by the second additive is not conducive to the circulation of the battery 200, and may increase the side reaction between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby increasing the internal resistance of the battery 200, resulting in a lower energy efficiency than the comparison battery 6. Furthermore, in the comparative battery 7, the mass fraction w2 of the first additive is too large, so that the values ​​of w2 / w1 and α / w1 are both too small. Although the first additive can preferentially undergo redox decomposition before the second additive and the generated product forms a film to slow down the side reaction between the electrolyte 100 and oxygen, the first additive produces too much acid, which attacks the structural stability of the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby reducing the stability of the interface film between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100 and increasing the internal resistance of the battery 200, thereby causing the capacity retention rate and energy retention rate of the comparative battery 7 to be low.

[0133] The data from Example 6 and Comparative Example 3 indicate that the planar shrinkage ratio α of the substrate and the shrinkage area S of the multiple lithium-supplementing particles during the lithium-supplementing process are equivalent in Example 6 and Comparative Example 3. Furthermore, in Example 6, the mass fraction w1 of the first additive satisfies the range of 0.01% ≤ w1 ≤ 2%, the mass fraction w2 of the second additive satisfies the range of 1% ≤ w2 ≤ 4%, and the values ​​of w2 / w1, α / w1, α×w3 / w1, and S / w1 are all within reasonable ranges. In Comparative Example 3, however, the value of w1 satisfies the range of 0.01% ≤ w1 ≤ 2%, and the mass fraction w2 of the second additive satisfies the range of 1% ≤ w2 ≤ 4%. However, the values ​​of w2 / w1, α / w1, and α×w3 / w1 are excessively large, resulting in a higher capacity retention rate after 500 cycles for the implementation battery 6 than for the comparative battery 3. Furthermore, the energy efficiency of the implementation battery 6 after 500 cycles is higher than that of the comparative battery 3. This is because: in the embodiment of battery 6, the planar shrinkage rate α of the substrate, the mass fraction w1 of the first additive and the mass fraction w2 of the second additive are all within a reasonable range and restrict each other. The lithium-supplementing particles do not release too much oxygen while releasing lithium ions. The products generated by the redox decomposition of the first additive can effectively block the side reaction between the electrolyte 100 and oxygen, and the acid generated by the first additive is not excessive, which can also prevent the second additive from being oxidized and decomposed, so that the second additive can maintain the interface stability between the positive electrode sheet 230 and / or the negative electrode sheet 210 and the electrolyte 100, thereby making the embodiment of battery 6 have both high capacity retention and energy efficiency. In comparative battery 3, the values ​​of w2 / w1, α / w1 and α×w3 / w1 are all too large. On the one hand, the shrinkage rate of the matrix is ​​too large and the mass fraction of the first additive is too small. The lithium-supplementing particles release too many lithium ions, and the total lithium release amount of the lithium-supplementing particles during the charge and discharge cycle is too much, which easily leads to local lithium deposition on the negative electrode 210. In addition, the lithium-supplementing particles release too much oxygen while releasing lithium ions, and the first additive produces fewer products of redox decomposition, making it difficult to prevent the side reaction of the oxygen released by the lithium ions with the electrolyte 100. The stability of the electrolyte 100 is poor, which in turn causes the capacity retention rate of comparative battery 3 to be low. On the other hand, if the mass fraction of the second additive is too large compared to the mass fraction of the first additive, when the battery 200 is charged, the first additive undergoes preferential redox decomposition and is consumed, but part of the second additive still undergoes redox decomposition to produce gas, resulting in a waste of the second additive. The gas produced by the second additive is not conducive to the circulation of the battery 200, and may increase the side reaction between the positive electrode plate 230 and / or the negative electrode plate 210 and the electrolyte 100, thereby increasing the internal resistance of the battery 200, resulting in a lower energy efficiency than the comparison battery 3.

[0134] The data from Comparative Examples 2, 8, and 9 show that when the mass fraction w2 of the second additive, the mass fraction w1 of the first additive, and the value of w2 / w1 are equal, as the planar shrinkage rate α of the substrate increases, the shrinkage area S, α / w1, and S / w1 of the multiple lithium-supplementing particles during the lithium replenishment process all increase. In Comparative Example 2, the planar shrinkage rate α of the substrate satisfies the range of 5% ≤ α ≤ 40%, the planar shrinkage rate α of the substrate in Comparative Example 8 is less than 5%, and the planar shrinkage rate α of the substrate in Comparative Example 9 is greater than 40%. As a result, the capacity retention rate of Comparative Battery 2 after 500 cycles is higher than the capacity retention rates of Comparative Batteries 8 and 9 after 500 cycles, and the energy efficiency of Comparative Battery 2 after 500 cycles is higher than the energy efficiency of Comparative Batteries 8 and 9 after 500 cycles. This is because: the planar shrinkage α of the substrate in Comparative Example 8 is too small. When the battery 200 is charged, the lithium-supplementing particles release too few lithium ions, making it difficult for the lithium-supplementing particles to replenish the active ions lost during the charge-discharge cycle of the battery 200. This results in fewer active ions in the battery 200, resulting in lower capacity retention and energy efficiency of Comparative Battery 8. The planar shrinkage α of the substrate in Comparative Example 9 is too large. When the battery 200 is charged, the lithium-supplementing particles release too many lithium ions, which easily leads to localized lithium deposition on the negative electrode 210. Correspondingly, the amount of oxygen released by the lithium-supplementing particles is too large, increasing the probability of side reactions between the electrolyte 100 and oxygen, thereby reducing the stability of the electrolyte 100. The products of the side reactions between the electrolyte 100 and oxygen may also increase the internal resistance of the battery 200, resulting in lower capacity retention and energy efficiency of Comparative Battery 9.

[0135] Please refer to Figures 5 and 6. An embodiment of the present application further provides an electric device 300. The electric device 300 includes: a device body 310 and a battery 200 provided in the present application. The battery 200 supplies power to the device body 310.

[0136] It can be understood that the battery 200 is electrically connected to the device body 310 .

[0137] In this embodiment, the battery 200 has good initial efficiency, cycle performance, and safety performance, which makes the battery 200 have a long service life. When the battery 200 is used to power the device body 310, the battery 200 can provide a stable power supply for the device body 310 to enable the normal operation of the device body 310.

[0138] Optionally, the power-consuming device 300 in the embodiment of the present application may be, but is not limited to, a portable electronic device such as a mobile phone, tablet computer, laptop computer, desktop computer, smart bracelet, smart watch, e-reader, game console, or similar. Alternatively, it may be a vehicle such as a car, truck, sedan, van, freight train, high-speed train, electric vehicle, or other similar vehicle. Furthermore, it may be various household appliances. The power-consuming device 300 in the embodiment of FIG. 6 of the present application is a cabinet of energy storage batteries 200.

[0139] It can be understood that the electrical device 300 described in this embodiment is merely a form of the electrical device 300 used by the battery 200, and should not be understood as a limitation on the electrical device 300 provided in this application, nor should it be understood as a limitation on the electrical device 300 provided in each embodiment of this application.

[0140] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places 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 in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, unless there is a contradiction between them.

[0141] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrolyte, wherein The electrolyte includes a first additive, which includes a cyclic substance containing two sulfonate groups. In the electrolyte, the mass fraction w1 of the first additive is in the range of 0.01%≤w1≤2%.

2. The electrolyte according to claim 1, wherein The structural formula of the first additive is: Wherein, said R1 is selected from H, C, C n H 2n+2 and C6H6; R2 is selected from H, C, C n H 2n+2 and one of C6H6, and n satisfies the range: 1≤n≤10.

3. The electrolyte according to claim 1, wherein The electrolyte also includes a second additive, which is a film-forming additive. The reduction potential of the first additive is higher than the reduction potential of the second additive, and the oxidation potential of the first additive is lower than the oxidation potential of the second additive. In the electrolyte, the mass fraction of the second additive is w2, then the relationship is satisfied: 2≤w2 / w1≤10.

4. The electrolyte according to claim 3, wherein The mass fraction w2 of the second additive satisfies the range: 1%≤w2≤4%.

5. The electrolyte according to claim 3, wherein The second additive includes at least one of vinylene carbonate, fluoroethylene carbonate, vinyl sulfate, tris(trimethylsilyl)phosphate, 1,3-propane sultone, adiponitrile, succinonitrile, and 1,3,6-hexanetrinitrile.

6. A battery, wherein: The battery comprises: negative electrode; A diaphragm, the diaphragm being arranged on one side of the negative electrode plate; A positive electrode sheet, the positive electrode sheet is arranged on the side of the separator away from the negative electrode sheet, the positive electrode sheet includes a positive electrode active layer and a positive electrode current collector layer, the positive electrode active layer is arranged on the surface of the positive electrode current collector layer, and the positive electrode active layer includes a plurality of lithium supplement particles; and The electrolyte according to any one of claims 1 to 5, wherein the electrolyte at least wets a portion of the positive electrode sheet and a portion of the negative electrode sheet, and the electrolyte further comprises a lithium salt.

7. The battery according to claim 6, wherein In the positive electrode active layer, the mass fraction of the lithium supplement particles is w3; the lithium supplement particles include a matrix and a coating layer, the coating layer is disposed on the outer periphery of the matrix, and the planar shrinkage rate of the matrix is α, and the relational expression is satisfied: 0.4 ≤ α × w3 / w1 ≤ 1.7; wherein, the chemical formula of the matrix is Li 1+r M 1-p N p O 4-s B s , and 0.1 < r < 6.1, 0 ≤ p < 0.99, 0 ≤ s < 0.1 are satisfied; M and N are each independently selected from at least one of iron, cobalt, nickel, titanium, zinc, magnesium, aluminum, manganese, vanadium, chromium, zirconium, copper, niobium, tantalum, tungsten, yttrium, and lanthanum, and B is selected from at least one of sulfur, nitrogen, fluorine, chlorine, and bromine.

8. The battery according to claim 7, wherein In the cross section of the positive electrode sheet, the area defined by the inner contour of the coating layer is S1, and after the lithium-supplementing particles release lithium ions, the area defined by the outer contour of the substrate is S2. The planar shrinkage rate α of the substrate satisfies the relationship: α = (S1-S2) / S1×100%, and the battery satisfies the relationship: 20≤α / w1≤60.

9. The battery according to claim 7, wherein The range of the plane shrinkage rate α of the substrate is: 5%≤α≤40%.

10. The battery according to claim 7, wherein In the positive electrode active layer, the mass fraction w3 of the lithium supplement particles is in the range of 0.5%≤w3≤5%.

11. The battery according to claim 7, wherein At a magnification of 5K, within a rectangular area of 22 μm × 15 μm, in the cross section of the positive electrode sheet, the number of the lithium supplement particles is multiple; the sum of the areas defined by the inner contours of the multiple coating layers is S3, and after the lithium supplement particles release lithium ions, the sum of the areas defined by the outer contours of the multiple substrates is S4. Then, the contraction area S of the multiple lithium supplement particles during the lithium supplement process satisfies the relationship: S = S3 - S4, and the range of S is 1.5 μm. 2 ≤S / w1≤8μm 2 .

12. The battery according to claim 11, wherein The range of the shrinkage area S of the plurality of lithium supplement particles during the lithium supplement process is: 0.1 μm 2 ≤S≤6μm 2 .

13. An electrical device, wherein: The electrical equipment includes: the device itself; and The battery according to any one of claims 6 to 12, wherein the battery is used to power the device body.

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