WO2023078367A1 - Secondary battery - Google Patents

Abstract

The present disclosure provides a secondary battery. At least one of a positive electrode plate, a negative electrode plate, and an electrolyte of the secondary battery comprises an additive having a small molecular weight and a short molecular chain segment; the additive can be fully mixed with an active substance, a conductive agent, and a binder in the positive electrode plate and the negative electrode plate; moreover, the additive can be in sufficient contact with each component in a positive electrode and a negative electrode, and is immersed into the internal pores of the electrode plates. In addition, the additive has good compatibility with electrolyte components in the electrolyte, and can be easily dissolved in the electrolyte within the addition amount of the present disclosure. Therefore, the additive of the present disclosure can form films on the surfaces of the active substances of the positive electrode and the negative electrode, can effectively improve the composition of a solid-state electrolyte film on the surfaces of the active substances of the positive electrode and the negative electrode, increases the content of a macromolecule component in a solid-state interface film, improves the conduction of electrons and lithium ions in the positive electrode plate and the negative electrode plate of the battery, improves the dynamics of the lithium ions in the electrode plates, avoids the internal resistance of the battery from increasing in a cycle process, and prolongs the cycle life.

Description

a secondary battery technical field

The disclosure belongs to the technical field of secondary batteries, and relates to a secondary battery.

Background of the invention

Lithium-ion batteries have been widely used in power vehicles, energy storage, drones, notebook computers, mobile phones, cameras and other products. The current commercial lithium-ion batteries are mainly composed of positive electrodes, negative electrodes, separators and electrolytes. Lithium-ion negative electrode materials are particularly important as an important component of lithium-ion batteries.

With the charging and discharging of the battery in the conventional battery system, especially during the first charging and discharging process, the electrochemical reaction of lithium ions in the positive and negative electrodes will cause the volume expansion of the negative electrode material, and the A solid interface film is formed on the surface of the electrode, and the solid interface film will continue to be generated and consumed during the charging and discharging process, resulting in a decrease in the effective transport capacity of ions and electrons inside the electrode sheet, and an increase in the internal resistance of the battery.

Therefore, it is particularly important to develop a secondary battery that can effectively improve the stability of the solid interface film, improve the effective transmission of ions and electrons inside the pole piece, and improve the cycle performance.

Contents of the invention

In order to improve the above technical problems, the present disclosure provides a secondary battery containing an additive. The battery containing additives can effectively improve the composition of the surface and internal interface film of the battery pole piece, improve the stability of the solid interface film, improve the effective transmission of ions and electrons inside the pole piece, reduce the volume change of the secondary battery, and improve Cycle performance of secondary batteries.

The purpose of this disclosure is achieved through the following technical solutions:

A secondary battery, the secondary battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte; at least one of the positive electrode sheet, the negative electrode sheet, or the electrolyte includes an additive, and the additive is selected from A monomeric compound consisting of more than two carbon-carbon double bond structures.

In one example, the secondary battery includes a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector, and the negative electrode active material layer includes Negative electrode active material, conductive agent, binder and the additive.

In one example, the secondary battery includes an electrolytic solution including the additive.

In one example, the secondary battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector, and the positive electrode active material layer includes positive electrode active material, conductive agent, binder and the additive.

In one example, the additive is selected from monomeric compounds having a structure shown in Formula 1:

In formula 1, R ₁ is the same or different, independently selected from H or organic functional groups;

R ₂ are the same or different, independently selected from H or organic functional groups;

R ₃ are the same or different, independently selected from H or organic functional groups;

R ₄ are the same or different, independently selected from nonexistent or linking groups;

_R is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted ether, substituted or unsubstituted alicyclic, substituted or unsubstituted alicyclic-alkyl, substituted or unsubstituted alkyl-alicyclic-alkyl, substituted or unsubstituted cycloalkyl containing heterocyclic atoms, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted cycloalkenyl containing heterocyclic atoms, substituted or unsubstituted (hetero)aryl, substituted or unsubstituted alkenyl-aryl-alkenyl, substituted or unsubstituted (hetero)aryl-alkylene-(hetero)aryl, substituted or unsubstituted (hetero)aryl-O-(hetero)aryl, substituted or unsubstituted (hetero)aryl-S-(hetero)aryl, substituted or unsubstituted alkoxy-(hetero)arylylene-aryl Alkyl-(hetero)arylylene-O-alkyl, *-Sn(substituted or unsubstituted alkyl) ₂ -*, substituted or unsubstituted alkyl-OP(=O)(OH)-O- Alkyl, substituted or unsubstituted alkyl-OP(=O)(halogen)-O-alkyl, substituted or unsubstituted alkyl-OP(=O)(alkyl)-O-alkyl, substituted or Unsubstituted alkyl-OP(=O)(O-alkyl)-O-alkyl, substituted or unsubstituted P(O-alkyl), substituted or unsubstituted isocyanurate (alkoxy ) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted isocyanurate (alkyl) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted N( Alkyl) ₃ , substituted or unsubstituted (alkyl) _n2 Si (O-Si (alkyl) (alkyl)) _n3 (n2, n3 are integers from 0 to 4 and n2+n3=4), substituted or Unsubstituted (alkyl) _n4 Si(O-alkyl) _n5 (n4, n5 are integers from 0 to 4 and n4+n5=4); when there is substitution, the substitution can be one or more, more They can be the same or different, and the substituted groups are selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si (Alkyl) ₃ , *-OP(=O)(OH) ₂ ;

* indicates the connection end;

n is an integer greater than or equal to 2.

In one example, the electrolyte contains the additive, and the content of the additive accounts for 0.01wt%-5wt% of the total mass of the electrolyte.

In one example, the additive is in the negative electrode active material layer of the negative electrode sheet, and the content of the additive is 0.001wt%-2wt% based on the total mass of the negative electrode active material layer.

In one example, the additive is in the positive active material layer of the positive electrode sheet, and the content of the additive is 0.001wt%-1.0wt% in mass percent based on the total mass of the positive active material layer.

In one example, the secondary battery is a lithium ion battery.

Terms and Definitions

Unless otherwise stated, the definitions of groups and terms described in this disclosure, including their definitions as examples, exemplary definitions, preferred definitions, definitions recorded in tables, definitions of specific compounds in the examples, etc., can be compared with each other Any combination and combination between. Such combinations and combined group definitions and compound structures should fall within the protection scope of the present disclosure.

As used in this disclosure, "halogen" refers to fluorine, chlorine, bromine and iodine.

"Alkyl" used in this disclosure alone or as a suffix or prefix is intended to include branched groups having 1 to 20, preferably 1-6 carbon atoms (or the specific number if a specific number of carbon atoms is provided). Chain and straight chain saturated aliphatic hydrocarbon groups. For example, "C _1-6 alkyl" means straight chain and branched chain alkyl having 1, 2, 3, 4, 5 or 6 carbon atoms, "C _2-4 alkyl" means having 2, 3 or 4 straight-chain or straight-chain alkyl groups of carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl base, neopentyl, n-hexyl, 2-hexyl or 3-hexyl.

"Alkenyl" used in this disclosure alone or as a suffix or prefix is intended to include compounds having 2 to 20, preferably 2-6 carbon atoms (or the specific number if a specific number of carbon atoms is provided) including Branched and straight-chain aliphatic hydrocarbon groups of alkenyl or alkenes. For example, " _C2-6 alkenyl" means an alkenyl group having 2, 3, 4, 5 or 6 carbon atoms. Examples of alkenyl groups include, but are not limited to, vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methylbut-2-enyl, 3 - methylbut-1-enyl, 1-pentenyl, 3-pentenyl and 4-hexenyl.

The term "aryl" as used in this disclosure refers to an aromatic ring structure composed of 5 to 20 carbon atoms. For example: aromatic ring structures containing 5, 6, 7 and 8 carbon atoms, which may be monocyclic aromatic groups such as phenyl; containing 8, 9, 10, 11, 12, 13 or 14 carbon atoms Ring structures, which may be polycyclic, eg naphthyl. Aryl rings may be substituted at one or more ring positions with those substituents described above. The term "aryl" also includes polycyclic ring systems having two or more rings in which two or more carbons are shared by two adjacent rings (the rings are "fused rings"), wherein at least One ring is aromatic and the other ring can be, for example, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl and/or heterocyclyl. Examples of polycyclic rings include, but are not limited to, 2,3-dihydro-1,4-benzodioxine and 2,3-dihydro-1-benzofuran.

The term "cycloaliphatic" as used in this disclosure is intended to include "cycloalkyl" and "cycloalkenyl".

As used in this disclosure, the term "cycloalkyl" is intended to include saturated ring groups having the indicated number of carbon atoms. These terms may include fused or bridged polycyclic ring systems. Cycloalkyl groups have 3 to 40 carbon atoms in their ring structure. In one embodiment, a cycloalkyl has 3, 4, 5 or 6 carbon atoms in its ring structure. For example, "C _3-6 cycloalkyl" represents a group such as cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

As used in this disclosure, the term "cycloalkenyl" is intended to include cyclic groups having the indicated number of carbon atoms that contain at least one double bond. These terms may include fused or bridged polycyclic ring systems. Cycloalkenyl has 3 to 40 carbon atoms in its ring structure. In one embodiment, a cycloalkenyl group has 3, 4, 5 or 6 carbon atoms in its ring structure. For example, "C _3-6 cycloalkenyl" represents a group such as cycloallyl, cycloenylbutyl, cycloenyl or cycloenylhexyl.

As used in this disclosure, the term "heteroaryl" refers to a heteroaromatic heterocycle having at least one ring heteroatom such as sulfur, oxygen, or nitrogen. Heteroaryl includes monocyclic and polycyclic systems (eg, having 2, 3 or 4 fused rings). Examples of heteroaryl groups include, but are not limited to, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, furyl, quinolinyl, isoquinolyl, thienyl, imidazolyl, thiazolyl, indole Base, pyrrolyl, oxazolyl, benzofuryl, benzothienyl, benzothiazolyl, isoxazolyl, pyrazolyl, triazolyl, tetrazolyl, indazolyl, 1,2,4 -thiadiazolyl, isothiazolyl, benzothienyl, purinyl, carbazolyl, benzimidazolyl, benzoxazolyl, azabenzoxazolyl, imidazothiazolyl, benzo[1 ,4]dioxolyl, benzo[1,3]dioxolyl, etc. In some embodiments, heteroaryl groups have 3 to 40 carbon atoms and in other embodiments 3 to 20 carbon atoms. In some embodiments, a heteroaryl group contains 3 to 14, 4 to 14, 3 to 7, or 5 to 6 ring-forming atoms. In some embodiments, a heteroaryl group has 1 to 4, 1 to 3, or 1 to 2 heteroatoms. In some embodiments, a heteroaryl has 1 heteroatom.

As used in this disclosure, the term "heterocyclyl" refers to a saturated, unsaturated or partially saturated monocyclic, bicyclic or tricyclic ring containing 3 to 20 atoms, wherein 1, 2, 3, 4 or 5 ring atoms are selected from Nitrogen, sulfur or oxygen, unless otherwise stated, which may be attached through carbon or nitrogen, wherein the -CH2- group is optionally replaced by -C(O)-; and wherein, unless otherwise stated, a ring nitrogen atom or a ring Sulfur atom optionally oxidized to form N-oxide or S-oxide or ring nitrogen atom optionally quaternized; where -NH in the ring is optionally substituted with acetyl, formyl, methyl or methanesulfonyl ; and the ring is optionally substituted with one or more halogens. It should be understood that when the total number of S atoms and O atoms in the heterocyclyl exceeds 1, these heteroatoms are not adjacent to each other. If the heterocyclyl is bicyclic or tricyclic, at least one ring may optionally be a heteroaromatic or aromatic ring, provided that at least one ring is non-heteroaromatic. If the heterocyclyl is monocyclic, it must not be aromatic. Examples of heterocyclic groups include, but are not limited to, piperidinyl, N-acetylpiperidinyl, N-methylpiperidinyl, N-formylpiperazinyl, N-methylsulfonylpiperazinyl, homopiperazinyl , piperazinyl, azetidinyl, oxetanyl, morpholinyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, dihydroindolyl, tetrahydropyranyl, dihydro -2H-pyranyl, tetrahydrofuryl, tetrahydrothiopyranyl, tetrahydrothiopyran-1-oxide, tetrahydrothiopyran-1,1-dioxide, 1H-pyridin-2-one and 2,5 - dioxoimidazolidinyl.

Beneficial effects of the present disclosure:

With the charging and discharging of the battery in the conventional battery system, especially in the first charging and discharging process, the electrochemical reaction of lithium ions in the positive and negative electrodes will cause the volume expansion of the negative electrode material, and the positive and negative electrodes will A solid interfacial film is formed on the surface of the active material material. The disclosure of the present invention adopts a monomer compound including two or more carbon-carbon double bond structures as an additive, and the carbon-carbon double bond in the additive undergoes electrochemical polymerization at a low potential to form a stable solid state on the surface of the positive and negative electrodes. Interface film, the solid interface film has the characteristics of high molecular weight, many active groups, and good stability, which can effectively slow down the occurrence of side reactions at the positive and negative electrode interfaces, reduce the increase in internal resistance during battery cycling, and improve battery cycle performance.

Specifically, the present disclosure provides a secondary battery, at least one of the positive electrode sheet, the negative electrode sheet and the electrolyte of the secondary battery includes the additive of the present disclosure. Due to the characteristics of small molecular weight and short molecular chain segment, the additive can be fully mixed with the active material, conductive agent and binder in the positive and negative electrodes, and the additive can fully contact each component in the positive and negative electrodes. Divide and immerse into the internal pores of the pole piece. In addition, the additive has good compatibility with the components of the electrolyte in the electrolyte, and can be easily dissolved in the electrolyte within the amount added in the present invention. That is, the additive of the present disclosure can form a film on the surface of the positive and negative active materials, can effectively improve the composition of the solid electrolyte film on the surface of the positive and negative active materials, increase the content of polymer components in the solid interface film, and improve the stability of the solid interface film. Improve the conductivity of electrons and lithium ions inside the positive and negative pole pieces of the battery, improve the dynamic performance of lithium ions inside the pole piece, avoid or reduce the increase in internal resistance of the battery during cycling, and improve the cycle performance and service life of the battery.

Modes of Carrying Out the Invention

<Secondary battery>

The present disclosure provides a secondary battery. The secondary battery includes a positive pole piece, a negative pole piece, and an electrolyte; wherein at least one of the positive pole piece, the negative pole piece, or the electrolyte includes Additives, the additives are selected from monomeric compounds including more than two carbon-carbon double bond structures.

In one example, the secondary battery includes a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector, and the negative electrode active material layer includes Negative electrode active material, conductive agent, binder and the additive.

In one example, the secondary battery includes an electrolytic solution including the additive.

In one example, the electrolytic solution includes a non-aqueous organic solvent, a lithium salt and the additive.

In one example, the content of the additive accounts for 0.01wt%-5wt% of the total mass of the electrolyte, for example, the content of the additive accounts for 0.01wt%, 0.05wt%, 0.05wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, or 5 wt%.

In one example, the secondary battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector, and the positive electrode active material layer includes positive electrode active material, conductive agent, binder and the additive.

According to a specific embodiment, the additive is selected from monomer compounds having the structure shown in Formula 1:

In formula 1, R ₁ is the same or different, independently selected from H or organic functional groups;

R ₂ are the same or different, independently selected from H or organic functional groups;

R ₃ are the same or different, independently selected from H or organic functional groups;

R ₄ are the same or different, independently selected from nonexistent or linking groups;

_R is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted ether, substituted or unsubstituted alicyclic, substituted or unsubstituted alicyclic-alkyl, substituted or unsubstituted alkyl-alicyclic-alkyl, substituted or unsubstituted cycloalkyl containing heterocyclic atoms, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted cycloalkenyl containing heterocyclic atoms, substituted or unsubstituted (hetero)aryl, substituted or unsubstituted alkenyl-aryl-alkenyl, substituted or unsubstituted (hetero)aryl-alkylene-(hetero)aryl, substituted or unsubstituted (hetero)aryl-O-(hetero)aryl, substituted or unsubstituted (hetero)aryl-S-(hetero)aryl, substituted or unsubstituted alkoxy-(hetero)arylylene-aryl Alkyl-(hetero)arylylene-O-alkyl, *-Sn(substituted or unsubstituted alkyl) ₂ -*, substituted or unsubstituted alkyl-OP(=O)(OH)-O- Alkyl, substituted or unsubstituted alkyl-OP(=O)(halogen)-O-alkyl, substituted or unsubstituted alkyl-OP(=O)(alkyl)-O-alkyl, substituted or Unsubstituted alkyl-OP(=O)(O-alkyl)-O-alkyl, substituted or unsubstituted P(O-alkyl), substituted or unsubstituted isocyanurate (alkoxy ) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted isocyanurate (alkyl) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted N( Alkyl) ₃ , substituted or unsubstituted (alkyl) _n2 Si (O-Si (alkyl) (alkyl)) _n3 (n2, n3 are integers from 0 to 4 and n2+n3=4), substituted or Unsubstituted (alkyl) _n4 Si(O-alkyl) _n5 (n4, n5 are integers from 0 to 4 and n4+n5=4); when there is substitution, the substitution can be one or more, more They can be the same or different, and the substituted groups are selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si (Alkyl) ₃ , *-OP(=O)(OH) ₂ ;

* indicates the connection end;

n is an integer greater than or equal to 2.

In an example, the n is an integer of 2-6, such as 2, 3, 4, 5 or 6.

In the present disclosure, the number of connection ends of _R5 is the same as n, for example, when n=2, the number of connection ends of _R5 is 2; when n=3, the number of connection ends of _R5 is 3; n=4 When n=5, the number of connecting ends of R ₅ is 4; when n=5, the number of connecting ends of R ₅ is 5; and so on.

In one example, R ₄ is the same or different, independently selected from nonexistent or *-C(R')2-O-**, *-C(=O)-O-**, *-C( =O)-S-**, *-C(R') ₂ -OC(=O)-**, R's are the same or different, independently selected from H or alkyl (such as C _1-6 alkyl ); wherein, * represents the connection end with the double bond, and ** represents the connection end with R ₅ .

In one example, R ₁ are the same or different, independently selected from H, alkyl (such as methyl or ethyl) or cyano (-CN).

In one example, R ₂ are the same or different, independently selected from H, alkyl (such as C _1-6 alkyl) or aryl (such as phenyl).

In one example, R ₃ are the same or different, independently selected from H, alkyl (eg C _1-6 alkyl) or aryl (eg phenyl).

In one example, R ₅ is selected from substituted or unsubstituted C _1-20 alkyl (such as C _1-12 alkyl), *-CH(R")-CH(R")-O-[CH(R ")-CH(R")-O] _n6 -CH(R")-CH(R")-* (n6=0, 1, 2..., R" is H or alkyl), substituted or unsubstituted C _1-6 alkyl-C _5-10 cycloalkyl-C _1-6 alkyl, substituted or unsubstituted adamantyl, chlorendyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthalene substituted or unsubstituted phenyl-alkylene-phenyl, substituted or unsubstituted phenyl-O-phenyl, substituted or unsubstituted phenyl-S-phenyl, substituted or unsubstituted _{C1 -6} alkyl-O-phenyl-alkylene-phenyl-OC _1-6 alkyl, fluorescein, *-Sn(C _1-6 alkyl) ₂ -*, substituted or unsubstituted C _{1- 6Alkyl} -OP(=O)(OH)-OC _1-6Alkyl , substituted or unsubstituted vinyl-phenyl-vinyl, substituted or unsubstituted isocyanurate (alkoxy) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted isocyanuric acid group (C _1-6 alkyl) _n1 (n1 can be 0, 1, 2 or 3); when substituted, The substitution can be one or more, and can be the same or different when multiple, and the substituted group is selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O )-O-*, *-O-Si(alkyl) ₃ , *-OP(=O)(OH) ₂ ;

In one example, the additive is selected from at least one of the compounds having the structure shown in Formula 2:

In Formula 2, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are as defined above.

In one example, the additive is selected from at least one of the compounds having structures shown in Formula 2-1, Formula 2-2, Formula 2-3, Formula 2-4, and Formula 2-5:

In Formula 2-1, Formula 2-2, Formula 2-3, Formula 2-4, and Formula 2-5, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are as defined above.

In one example, in formula 2-1 and formula 2-2, R ₅ is selected from substituted or unsubstituted C _1-20 alkyl (such as C _1-12 alkyl), *-CH(R")-CH (R")-O-[CH(R")-CH(R")-O] _n6 -CH(R")-CH(R")-*(n6=0, 1, 2..., R" is H or C _1-6 alkyl), substituted or unsubstituted *-cyclohexane-*, substituted or unsubstituted *-CH ₂ -cyclohexane-CH ₂ -*, substituted or unsubstituted adamantane, Chlorenyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted bisphenol A, substituted or unsubstituted phenyl-O-phenyl, substituted or unsubstituted phenyl -S-phenyl, substituted or unsubstituted *-CH ₂ CH ₂ -bisphenol A -CH ₂ CH ₂ -*, fluorescein, *-Sn(C _1-6 alkyl) ₂ -*, substituted or unsubstituted C _1-6 alkyl-OP(=O)(OH)-OC _1-6 alkyl, substituted or unsubstituted C _1-6 alkyl-OP(=O)(halogen)-OC _{1 -6} alkyl, substituted or unsubstituted vinyl-phenyl-vinyl, substituted or unsubstituted isocyanuric acid group (C _1-6 alkoxy) _n1 (n1 can be 0, 1, 2 or 3 ); when there is substitution, the substitution can be one or more, and can be the same or different when multiple, and the substituted group is selected from halogen, -OH, alkyl-OC(=O)-*, Alkyl-C(=O)-O-*, *-O-Si(alkyl) ₃ , *-OP(=O)(OH) ₂ .

In one example, in formula 2-2, R ₅ is selected from substituted or unsubstituted phenyl-S-phenyl; when there is substitution, the substitution can be one or more, and multiple can be the same or can be Different, the substituted group is selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si(alkyl) ₃ , *-OP(=O)(OH) ₂ .

In one example, in formula 2-3, R ₅ is selected from substituted or unsubstituted C _1-20 alkyl (such as C _1-12 alkyl); when there is substitution, the substitution can be one or more , multiple times can be the same or different, and the substituted groups are selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O -Si(alkyl) ₃ , *-OP(=O)(OH) ₂ .

In one example, in formula 2-4, R ₅ is selected from substituted or unsubstituted C _1-20 alkyl (such as C _1-12 alkyl), substituted or unsubstituted *-cyclohexane-*, chlorine Bacteric acid group, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted vinyl-phenyl-vinyl; when there is substitution, the substitution can be one or more, multiple They can be the same or different, and the substituted groups are selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si (Alkyl) ₃ , *-OP(=O)(OH) ₂ .

In one example, in formula 2-5, R ₅ is selected from substituted or unsubstituted C _1-20 alkyl (such as C _1-12 alkyl), substituted or unsubstituted C _1-6 alkyl-OP ( = O) (halogen) -OC _1-6 alkyl, substituted or unsubstituted vinyl-phenyl-vinyl, substituted or unsubstituted isocyanuric acid group (C _1-6 alkoxy) _n1 (n1 can be 0, 1, 2 or 3); when there is substitution, the substitution can be one or more, and can be the same or different when multiple, and the substituted group is selected from halogen, -OH, alkyl -OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si(alkyl) ₃ , *-OP(=O)(OH) ₂ .

In one example, the additive is selected from at least one of the compounds having the structure shown in formula 3:

In Formula 3, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are as defined above.

In one example, in formula 3, R ₄ is the same or different, independently selected from nonexistent or *-C(=O)-O-** and *-CH2-OC(=O)-**, R 'Identical or different, independently selected from H or alkyl (such as C _1-6 alkyl); wherein, * represents the connection end with the double bond, ** represents the connection end with R ₅ .

In one example, in formula 3, R ₅ is selected from substituted or unsubstituted C _1-20 alkyl (such as C _1-12 alkyl), substituted or unsubstituted phenyl, substituted or unsubstituted N(C _1-6 alkyl) ₃ , substituted or unsubstituted isocyanuric acid group (C _1-6 alkyl) _n1 (n1 can be 0, 1, 2 or 3) substituted or unsubstituted C _1-6 alkyl -OP(=O)(C _1-6 alkyl)-OC _1-6 alkyl, substituted or unsubstituted C _1-6 alkyl-OP(=O)(-OC _1-6 alkyl)-OC _1-6 alkyl, substituted or unsubstituted P(-OC _1-6 alkyl) ₃ ; when there is substitution, the substitution can be one or more, and multiple can be the same or different, the substitution The group selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si(alkyl) ₃ , *-OP(= O)(OH) ₂ .

In one example, the additive is selected from at least one of the compounds having the structure shown in formula 4:

In Formula 4, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are as defined above.

In one example, the additive is selected from at least one of the compounds having the structure shown in formula 5:

In Formula 5, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are as defined above.

In one example, the molecular weight of the additive is 100Da-6000Da, for example, the molecular weight of the additive is 100Da, 500Da, 1000Da, 1500Da, 2000Da, 2500Da, 3000Da, 4000Da, 5000Da, 6000Da.

In one example, the additive is selected from at least one of the following compounds: 1,5-pentanediol diacrylate (CAS No.: 36840-85-4), pentaerythritol tetraacrylate (CAS No.: 4986-89 -4), 1,6-hexanediol dimethacrylate (CAS number: 6606-59-3), 1,4-butanediol dimethacrylate (CAS number: 2082-81-7), Triethylene glycol dimethacrylate (CAS number: 109-16-0), 1,4-butanediol diacrylate (CAS number: 1070-70-8), triethylene glycol diacrylate (CAS No.: 1680-21-3), tripropylene glycol diacrylate (CAS No.: 42978-66-5), 1,10-decanediol diacrylate (CAS No.: 13048-34-5), diethyl Glycol Dimethacrylate (CAS No.: 2358-84-1), Neopentyl Glycol Diacrylate (CAS No.: 2223-82-7), Ethylene Glycol Dimethacrylate (CAS No.: 97- 90-5), 1,3-butanediol dimethacrylate (CAS No.: 1189-08-8), tetraethylene glycol dimethacrylate (CAS No.: 109-17-1), tetraglycol Alcohol Diacrylate (CAS No.: 17831-71-9), Fluorescein O,O'-Diacrylate (CAS No.: 7262-39-7), Bisphenol A Dimethacrylate (CAS No.: 3253- 39-2), 3-allyloxypropyl methacrylate (CAS No.: 77757-02-9), bisphenol A diacrylate (CAS No.: 4491-03-6), triisocyanurate (2-Acryloyloxyethyl) ester (CAS No.: 67893-00-9), 2,2,6,6-tetrabromobisphenol A diacrylate (CAS No.: 55205-38-4), 1, 3-Propanediol dimethacrylate (CAS number: 7559-82-2), cyclohexanedimethanol diacrylate (CAS number: 67905-41-3), cyclohexanedimethanol dimethacrylate (CAS No.: 52892-97-4), 2-[(trimethylsilyl)oxy]-1,3-propanediylbis(2-methacrylate) (CAS No.: 247244-66-2), Glyceryl trimethacrylate (CAS No.: 7401-88-9), 2-butene-1,4-dimethacrylate (CAS No.: 18621-77-7), 2,2',2"- Nitrilotriethanol trimethacrylate (CAS No.: 13884-43-0), 2,2,6,6-tetrabromobisphenol A dimethacrylate (CAS No.: 42146-13-4), 1-Methyl-1,2-ethylenediyl diacrylate (CAS No.: 25151-33-1), 2-(phosphoryloxy)propane-1,3-diyl dimethacrylate (CAS No. : 67829-13-4), dibutyl tin dimethacrylate (CAS number: 15257-25-7), sorbitol pentaacrylate (CAS number: 53123-67-4), 3-methyl- 1,5-pentanediyl diacrylate (CAS No.: 64194-22-5), 1,2,3-propanetriyl triacrylate (CAS No.: 5459-38-1), pentaerythritol tetrakis (2- Cyano-3,3-diphenylacrylate) (CAS No.: 178671-58-4), Neopentyl Glycol Dimethacrylate (CAS No.: 1985-51-9), Diethylene Glycol Diacrylate (CAS No.: 4074-88-8), Dipropylene Glycol Diacrylate (CAS No.: 57472-68-1), 1,3-Butanediol Diacrylate (CAS No.: 19485-03-1), 1, 3-Adamantyl dimethacrylate (CAS No.: 122066-43-7), bis(4-methacryloylthiophenyl) sulfide (CAS No.: 129283-82-5), ethylene diacrylate Alcohol Esters (CAS No.: 2274-11-5), Dipentaerythritol Pentaacrylate (CAS No.: 60506-81-2), Ethoxylated Bisphenol A Dimethacrylate (CAS No.: 41637-38-1), Tris(2-acryloyloxyethyl)isocyanurate (CAS No.: 40220-08-4), diallyl phthalate (CAS No.: 131-17-9), trimellitic acid tris Allyl ester (CAS No.: 17832-16-5), diallyl-n-propyl isocyanurate (CAS No.: 5320-25-2), diallyl allyl phosphonate (CAS No.: 3479-30-9), Triallyl Phosphate (CAS No.: 1623-19-4), Diallyl Metaphthalate (CAS No.: 1087-21-4), 1,2,4-Benzene Triallyl Triformate (CAS No.: 2694-54-4), Triallyl Phosphite (CAS No.: 102-84-1), Tetraallyl Silicate (CAS No.: 1067-43- 2), diallyl chlorophosphate (CAS No.: 16383-57-6), diallyl chlorendate (CAS No.: 3232-62-0), diallyl azelate (CAS No.: 3136-99-0), triallyl citrate (CAS No.: 6299-73-6), diallyl malate (CAS No.: 32099-14-2), diallyl iso Cyanurate (CAS No. 6294-79-7), Diethyl 1,4-Benzene Diacrylate (CAS No. 17088-28-7), Diethyl Diallyl Malonate (CAS No.: 3195-24-2), dimethyl diallyl malonate (CAS No.: 35357-77-8), triallyl isocyanurate (CAS No.: 1025-15-6), 1, Ethyl 1,1-trimethylol triacrylate (CAS No.: 19778-85-9), Diallyl Isocyanurate (CAS No.: 1081-69-2), Diene 1,4-cyclohexanedicarboxylate Propyl ester (CAS No.: 20306-22-3), 2,2,3,3,4,4-hexafluoro-1,5-diacrylate pentyl ester (CAS No.: 678-95-5), 1, 4-phenylene diacrylate (CAS No.: 6729-79-9), diallylnaphthalene-2,3-dicarboxylate (CAS No. 52640-63-8), 3-(2-methyl Prop-2-enoyloxy)propyl 2-methylprop-2-enoate (CAS No.: 1188-09-6), trimethylolpropyl trimethacrylate (CAS No.: 102068-89 -3), di(methacryloyloxyethyl) phosphate (CAS No.: 32435-46-4), 1,1,1-trimethanol ethyl trimethacrylate (CAS No.: 24690-33- 3), pentaerythritol tetramethacrylate (CAS number: 118541-94-9), 2,2-dibromo-neopentyl glycol diacrylate (CAS number: 41223-11-4), neopentyl dimethacrylate Glycol ester (CAS No.: 104182-97-0), 2-methyl-2-propionic acid-1,1-[oxybis(methyl-2,1-ethanediyl)] ester (CAS No. : 64111-89-3), methacryloxypropyl tris(vinyldimethylsiloxy)silane (CAS No.: 17096-10-5), dipropylene phthalate (CAS No.: 131 -17-9), 2,2',2"-nitrilotriethanol trimethacrylate (CAS No.: 13884-43-0).

In the present disclosure, the additives may be prepared by conventional methods in the art, or may be purchased through commercial channels.

<Negative pole piece>

In one example, based on the total weight of the negative electrode active material layer, the negative electrode active material layer includes the following components in mass percentage:

73wt%-98.5wt% negative electrode active material, 0.5wt%-15wt% conductive agent, 0.999wt%-10wt% binder, 0.001wt%-2wt% additive.

Exemplarily, based on the total weight of the negative electrode active material layer, the mass percentage of the negative electrode active material is 73wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt%, 81wt% %, 82wt%, 83wt%, 84wt%, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt% or 98.5wt%.

Exemplarily, based on the total weight of the negative electrode active material layer, the mass percentage of the conductive agent is 0.5wt%, 0.8wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%.

Exemplarily, based on the total weight of the negative electrode active material layer, the mass percentage of the binder is 0.999wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%.

Exemplarily, based on the total weight of the negative electrode active material layer, the mass percentage of the additive is 0.001wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.25wt%, 0.55wt%, 0.65 wt%, 0.70 wt%, 0.75 wt%, 0.85 wt%, 0.90 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, or 2 wt%. When the additive content is greater than 2wt%, if the additive content is too high, the interfacial film on the surface of the negative electrode/negative active material will be too thick, causing the internal resistance of the battery to increase, thereby making the pole piece capacity low, the pole piece lithium conduction network deteriorated, and the Battery performance; when the additive content is less than 0.001wt%, the additive content is too low, and the generated interfacial film content is not enough, which makes the solid interfacial film structure on the surface of the formed negative electrode/negative active material unstable, thereby reducing battery performance.

In one example, the density on one side of the negative electrode sheet is 0.5 mg/cm ² to 18 mg/cm ² , for example, the density on one side of the negative electrode sheet is 0.5 mg/cm ² , 1 mg/cm 2 cm ² , 1.5mg/cm ² , 2mg/cm ² , 2.5mg/cm ² , 3mg/cm ² , 4mg/cm ² , 5mg/cm 2 , 6mg/cm ² , 7mg/cm ² , ^10mg /cm ² , 13 mg/cm ² , 15 mg/cm ² , 18 mg/cm ² .

In one example, the negative electrode collector has a thickness of 3 μm˜15 μm, such as μm, 4 μm, 5 μm, 8 μm, 10 μm, 12 μm or 15 μm, preferably 4 μm˜10 μm.

According to a specific embodiment, the thickness of the negative electrode active material layer (the thickness of the negative electrode active material layer on one side after rolling) is 20 μm to 150 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm or 150 μm, preferably 30 μm to 120 μm.

In one example, the negative electrode active material is selected from silicon, SiO _x (0<X<2), lithium-silicon alloy, silicon alloy, artificial graphite, natural graphite, hard carbon, soft carbon, mesophase microspheres, fullerene ene, graphene, coke, carbon fiber, boron and its derivatives (such as boron powder, boron oxide), aluminum and its derivatives (such as aluminum powder, lithium aluminum alloy), magnesium and its derivatives (such as magnesium, magnesium aluminum alloy ), bismuth and its derivatives (such as bismuth, lithium-bismuth alloy), nickel and its derivatives (such as nickel, lithium-nickel alloy, lithium nickel nitride), silver and its derivatives (such as silver powder, lithium-silver alloy), zinc and its derivatives (such as zinc powder, zinc-lithium alloy, zinc nitride), titanium and its derivatives (such as titanium powder, lithium titanate, titanium dioxide, lithium-titanium alloy, etc.), gallium and its derivatives (such as gallium, lithium Gallium alloy), indium and its derivatives (such as indium powder, lithium indium alloy), tin and its derivatives (such as tin powder, tin oxide, tin oxide, tin sulfate), lithium nitride, copper nitride, etc. at least one.

In one example, the conductive agent is selected from at least one of conductive carbon black, Ketjen black, conductive fiber, conductive polymer, acetylene black, carbon nanotubes, graphene, flake graphite, conductive oxide, and metal particles .

In one example, the binder is selected from polyvinylidene fluoride and its copolymers, polytetrafluoroethylene and its copolymers, polyacrylic acid and its copolymers, polyvinyl alcohol and its copolymers, polystyrene butadiene rubber and At least one of its copolymer, polyimide and its copolymer, polyethyleneimine and its copolymer, polyacrylate and its copolymer, carboxymethylcellulose sodium and its copolymer.

<Preparation method of negative electrode sheet>

The present disclosure also provides a preparation method of the negative electrode sheet, the preparation method comprising the following steps:

The solvent, the negative electrode active material, the conductive agent, the binder and the additive are uniformly mixed to prepare the negative electrode slurry; the negative electrode slurry is coated on the surface of one or both sides of the negative electrode current collector, and dried to prepare the The negative pole piece.

In one example, the negative electrode slurry contains 150-350 parts by mass of solvent, 73-98.5 parts by mass of negative electrode active material, 0.5-15 parts by mass of conductive agent, 0.001-2 parts by mass of additives, 0.999-10 parts by mass of parts by mass of binder.

In one example, the solvent is at least one selected from water, acetonitrile, benzene, toluene, xylene, acetone, tetrahydrofuran, hydrofluoroether, and N-methylpyrrolidone.

In one example, the negative electrode slurry is preferably sieved, for example, through a 200-mesh sieve.

In one example, the temperature of the drying treatment is 80°C-115°C, and the time of the drying treatment is 6-36 hours.

<Positive pole piece>

In one example, based on the total weight of the positive electrode active material layer, the positive electrode active material layer includes the following components in mass percentage: 84wt% to 98.5wt% of the positive electrode active material, 0.5wt% to 10wt% conductive agent, 0.5wt%-5wt% binder, 0.001wt%-1wt% additive.

Exemplarily, the content of the positive active material in the total mass of the positive active material layer is 84wt%, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt% , 93wt%, 94wt%, 95wt%, 96wt%, 97wt% or 98.5wt%.

Exemplarily, the content of the conductive agent is 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt% in mass percent of the total mass of the positive electrode active material layer , 9wt% or 10wt%.

Exemplarily, the content of the additive is 0.001wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.25wt%, 0.55wt%, 0.65wt%, 0.70wt%, 0.75wt%, 0.85wt%, 0.90wt%, 1.0wt%. When the additive content is greater than 1wt%, the additive content is too high, which will lead to a decrease in the active material content of the positive electrode sheet, and the additive will form too thick a film on the surface of the positive electrode active material material, causing the internal impedance of the electrode sheet to increase, thereby making the electrode sheet capacity low. The lithium-conducting conductive network inside the pole piece is poor, which in turn affects the performance of the battery; when the additive content is less than 0.001wt%, the additive content is too low, the amount of film formation is small and the film formation property is poor, and the interface film structure formed on the surface of the positive pole piece If the amount is small and the structure of the formed interfacial film is unstable, the performance of the battery cannot be improved.

Exemplarily, based on the total weight of the positive electrode active material layer, the content of the binder in the mass percentage of the total mass of the positive electrode active material layer is 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt% or 5wt%.

In one example, the positive electrode active material is selected from lithium iron phosphate (LiFePO ₄ ), lithium cobalt oxide (LiCoO ₂ ), lithium nickel cobalt manganese oxide (L _z Ni _x CoyMn _1-xy O ₂ , wherein 0.95≤z≤ 1.05, x>0, y>0, 0<x+y<1), lithium manganate (LiMnO ₂ ), lithium nickel cobalt aluminate (L _z Ni _x Co _y Al _1-xy O ₂ , where 0.95≤z ≤1.05, x>0, y>0, 0.8≤x+y<1), lithium nickel cobalt manganese aluminate (Li _z Ni _x Co _y Mn _w Al _1-xyw O ₂ , where 0.95≤z≤1.05, x >0, y>0, w>0, 0.8≤x+y+w<1), nickel-cobalt-aluminum-tungsten materials, lithium-rich manganese-based solid solution cathode materials (xLi ₂ MnO ₃ ·(1-x)LiMO ₂ , where M=Ni/Co/Mn), lithium nickel cobalt oxide (LiNi _x Co _y O ₂ , where x>0, y>0, x+y=1), lithium nickel titanium magnesium oxide (LiNi _x Ti _y Mg _z O ₂ , where x>0, y>0, z>0, x+y+z=1), lithium nickelate (Li ₂ NiO ₂ ), spinel lithium manganate (LiMn ₂ O ₄ ), nickel-cobalt One or more combinations of tungsten materials.

In one example, the conductive agent includes one or more of conductive carbon black, Ketjen black, conductive fiber, conductive polymer, acetylene black, carbon nanotubes, graphene, flake graphite, conductive oxide, and metal particles kind.

In one example, the binder is selected from at least one of polyvinylidene fluoride and its copolymers, polytetrafluoroethylene and its copolymers, polyacrylic acid and its copolymers, polyhexafluoropropylene and its copolymers .

In one example, the density on one side of the positive pole piece is 2 mg/cm ² -30 mg/cm ² , for example, the density on one side of the positive pole piece is 2 mg/cm ² , 3 mg/cm ² , 4mg/cm ² , 5mg/cm ² , 10mg/cm ² , 12mg/cm ² , 15mg/cm 2 , 18mg/cm ² , 20mg/cm ² , 25mg/cm ² , ^30mg /cm ² .

In one example, the thickness of the positive electrode active material layer (the thickness of the positive electrode active material layer on one side after rolling) is 10 μm to 200 μm, such as 10 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm , 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 190 μm or 200 μm, preferably 50 μm to 100 μm.

<Preparation method of positive electrode sheet>

The present disclosure also provides a preparation method of the positive pole piece, the preparation method comprising the following steps:

The solvent, the positive electrode active material, the conductive agent, the binder and the additive are uniformly mixed to prepare the positive electrode slurry; the positive electrode slurry is coated on the surface of one or both sides of the positive electrode current collector, and dried to prepare the The positive pole piece.

In one example, the positive electrode slurry contains 100-200 parts by mass of solvent, 84-98.5 parts by mass of positive electrode active material, 0.5-10 parts by mass of conductive agent, 0.001-1 part by mass of the additive, 0.5 ~5 parts by mass of binder.

In one example, the solvent is at least one selected from benzene, toluene, xylene, acetone, tetrahydrofuran, hydrofluoroether, and N-methylpyrrolidone.

In one example, the positive electrode slurry is preferably sieved positive electrode slurry, for example, passed through a 200-mesh sieve.

In one example, the temperature of the drying treatment is 80°C-120°C, and the time of the drying treatment is 12-48 hours.

<Electrolyte>

In one example, the lithium salt is selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisoxalate borate, lithium difluorooxalate borate, lithium difluorobisoxalate phosphate, lithium tetrafluorooxalate phosphate, lithium difluorophosphate, perchloric acid At least one of lithium, lithium bisfluorosulfonamide, and lithium bistrifluoromethylsulfonyl imide.

In one example, the non-aqueous organic solvent is selected from a mixture prepared by mixing at least one of cyclic carbonates with at least one of linear carbonates and linear carboxylates in any proportion.

Preferably, the cyclic carbonate is selected from at least one of ethylene carbonate and propylene carbonate, and the linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate One, the linear carboxylate is selected from at least one of ethyl propionate, propyl propionate and propyl acetate.

In one example, in the electrolyte solution, based on the total mass of 100wt%, the mass fraction of the cyclic carbonate is 10wt% to 50wt% (for example, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%) %, 35wt%, 40wt%, 45wt%, 50wt%), the mass fraction of the linear carbonate and/or linear carboxylate is 50wt% ~ 90wt% (for example, 50wt%, 55wt%, 60wt%, 65wt% , 70wt%, 75wt%, 80wt%, 85wt%, 90wt%).

In one example, the content of the additive accounts for 0.001wt%-3wt% of the total mass of the electrolyte, such as 0.001wt%, 0.15wt%, 0.25wt%, 0.55wt%, 0.65wt%, 0.70wt% , 0.75wt%, 0.85wt%, 0.90wt%, 1.0wt%, 1.2wt%, 1.5wt%, 2wt%, 2.5wt%, 3.0wt%; when the content of the additive is higher than 3.0wt%, the additive exists Macromolecular substances, excessive additives will increase the viscosity of the electrolyte, resulting in poor wettability of the electrolyte, and at the same time, a large number of functional groups in the excessive additives will gather on the surface of the pole piece, which will easily lead to a large impedance of the solid electrolyte membrane on the surface of the electrode active material. There is great resistance to the deintercalation of lithium ions at the interface between the positive and negative electrodes, resulting in a rapid degradation of the performance of the lithium ion battery; There are too few film-forming products formed, which have little influence on battery performance.

<Preparation method of electrolyte solution>

The present disclosure also provides a preparation method of the above-mentioned electrolyte, and the preparation method includes the following steps:

The electrolyte solution is prepared by mixing the non-aqueous organic solvent, the lithium salt and the additive.

Exemplarily, the method includes the following steps:

In an argon atmosphere glove box with a water content of <10ppm, the non-aqueous organic solvent, lithium salt and additives are uniformly mixed according to a certain mass ratio to obtain an electrolyte.

<Li-ion battery>

In one example, the secondary battery is a lithium ion battery.

The present disclosure will be further described in detail in conjunction with specific embodiments below. It should be understood that the following examples are only for illustrating and explaining the present disclosure, and should not be construed as limiting the protection scope of the present disclosure. All technologies implemented based on the above contents of the present disclosure are covered within the intended protection scope of the present disclosure.

The experimental methods used in the following examples are conventional methods unless otherwise specified; the reagents and materials used in the following examples can be obtained from commercial sources unless otherwise specified.

Example 1

In this embodiment, the negative electrode sheet includes the additive.

1) Preparation of positive pole piece:

Mix 96g positive electrode active material nickel-cobalt-manganese ternary material (NCM811), 1.5g binder polyvinylidene fluoride (PVDF), 1.5g conductive carbon black, 1g conductive carbon nanotubes, add 150g N-methyl Pyrrolidone (NMP) was stirred under the action of a vacuum mixer until the mixed system formed a positive electrode slurry with uniform fluidity; the positive electrode slurry was uniformly coated on an aluminum foil with a thickness of 13 μm; after being dried at 100°C for 36 hours, pumping The pole piece is obtained after vacuum treatment, and the pole piece is rolled and cut to obtain the positive pole piece;

2) Preparation of negative pole piece:

50g natural graphite, 23g silicon oxide, 10g conductive agent single-wall carbon nanotube (SWCNT), 5g conductive agent conductive carbon black (SP), 2g additive ethylene glycol dimethacrylate, 4g binder carboxymethyl Sodium cellulose (CMC), 6g binder styrene-butadiene rubber (SBR), 200g deionized water are made into slurry with a wet process, coated on the surface of the negative electrode current collector copper foil, dried, rolled and Die-cutting to obtain the negative pole piece;

3) Preparation of electrolyte:

In a glove box filled with argon gas with qualified water and oxygen content, mix ethylene carbonate, propylene carbonate, diethyl carbonate, and n-propyl propionate evenly according to the mass ratio of 35:10:10:45, and then pour them into Quickly add 1.08mol/L fully dried lithium hexafluorophosphate (LiPF ₆ ), stir evenly to prepare an electrolyte;

4) Preparation of lithium-ion battery:

The positive pole piece, the negative pole piece and the diaphragm obtained above are used to prepare a lithium-ion battery cell, and after liquid injection packaging and welding, a lithium-ion battery is obtained.

Comparative example 1.1

The concrete process of comparative example 1.1 is with reference to embodiment 1, and the poly(ethylene glycol dimethacrylate) of quality equal to ethylene glycol dimethacrylate is added in the main difference comparative example 1.1, wherein, poly(ethylene glycol dimethacrylate) Methacrylate) is the polymer of ethylene glycol dimethacrylate and azobisisobutyronitrile polymerized at 60°C. The polymer cannot detect the C=C double bond peak through infrared. Other conditions and examples 1 consistent.

Comparative example 1.2

The specific process of Comparative Example 1.2 refers to Example 1, the main difference is that no ethylene glycol dimethacrylate is added in Comparative Example 1.2, and other conditions are consistent with Example 1.

Embodiment 2-6 and other comparative examples

The specific processes of Examples 2-6 and other comparative examples refer to Example 1. The main differences are the process conditions of the negative electrode sheet, the amount of each component added, and the type of each component material. See Table 1 and Table 2 for details.

The composition of the negative pole sheet of table 1 embodiment and comparative example

The composition of the negative pole sheet of table 2 embodiment and comparative example

Carry out performance test to the battery that above-mentioned embodiment and comparative example prepare:

(1) Battery internal resistance AC impedance test method: use Metrohm Swiss Metrohm PGSTAT302N chemical workstation in the range of 100KHz-0.1mHz, 25°C to conduct AC impedance test on 50% SOC lithium-ion battery, the test results are listed in Table 3 .

The battery internal resistance AC impedance test result of table 3 embodiment and comparative example

The internal resistance test results during the battery cycle show that the internal resistance of the lithium ion battery prepared in the embodiment of the present disclosure is smaller than that of the lithium ion battery prepared in the comparative example during the cycle process. The main reason is that the additives added in the disclosure can form a solid interface film on the surface of the negative electrode/negative active material. The solid interface film of the present disclosure is different from the solid interface film on the surface of the conventional negative electrode/negative active material. It has the characteristics of high-speed lithium conduction, and can The rapid conduction of lithium ions passes through, so the prepared lithium-ion battery has lower internal resistance, and at the same time, the increase in internal resistance during the cycle of the lithium-ion battery is small, which has certain advantages.

(2) Battery cycle performance test method: Lithium-ion batteries are charged and discharged in a blue battery charge and discharge test cabinet. The test conditions are 25°C, 1C/1C charge and discharge. The test results are listed in Table 4.

The battery cycle performance test result of table 4 embodiment and comparative example

Example 7

In this embodiment, the positive electrode sheet includes the additive.

1) Preparation of positive pole piece:

Mix 98.5g positive electrode active material lithium cobaltate, 0.5g binder polyvinylidene fluoride (PVDF), 0.5g conductive carbon black, 0.5g additive diallyl phthalate, add 200g N-methyl Pyrrolidone (NMP) was stirred under the action of a vacuum mixer until the mixed system formed a positive electrode slurry with uniform fluidity; the positive electrode slurry was uniformly coated on an aluminum foil with a thickness of 12 μm; after being dried at 100°C for 32 hours, pumping The pole piece is obtained after vacuum treatment, and the pole piece is rolled and cut to obtain the positive pole piece;

2) Preparation of negative pole piece:

97g graphite, 0.5g conductive agent single-wall carbon nanotube (SWCNT), 0.5g conductive agent conductive carbon black (SP), 1g binder sodium carboxymethylcellulose (CMC), 1g binder styrene-butadiene rubber ( SBR), 500g deionized water, make slurry with wet process, be coated on the surface of negative electrode current collector copper foil, obtain negative electrode pole piece through drying, rolling and die-cutting;

3) Electrolyte preparation:

In a glove box filled with argon gas with qualified water and oxygen content, mix ethylene carbonate, propylene carbonate, diethyl carbonate, and n-propyl propionate evenly according to the mass ratio of 20:10:15:55, and then pour them into Quickly add 1 mol/L fully dried lithium hexafluorophosphate (LiPF ₆ ), stir evenly to prepare an electrolyte;

4) Preparation of lithium ion battery

The positive pole piece and the negative pole piece obtained above are prepared into lithium-ion battery cells, and after liquid injection packaging and welding, a lithium-ion battery is obtained.

Comparative example 7.1

The specific process of Comparative Example 7.1 refers to Example 7. The main difference is that in Comparative Example 7.1, dipropyl phthalate with the same quality as diallyl phthalate and no C=C double bond structure is added. Other conditions are the same as Embodiment 7 is consistent.

Comparative example 7.2

The specific process of Comparative Example 7.2 refers to Example 7, the main difference is that no diallyl phthalate is added in Comparative Example 7.2, and other conditions are consistent with Example 1.

The specific processes of Examples 8-12 and other comparative examples refer to Example 7. The main differences are the process conditions of the positive electrode sheet, the content of each component, and the type of material of each component. See Table 5 and Table 6 for details.

The composition of the positive pole piece of table 5 embodiment and comparative example

The composition of the positive pole piece of table 6 embodiment and comparative example

Carry out performance test to the battery that above-mentioned embodiment and comparative example prepare:

(1) AC impedance test method of battery internal resistance: Use Metrohm PGSTAT302N chemical workstation in the range of 100KHz-0.1mHz, 25°C to conduct AC impedance test on 50% SOC lithium-ion battery, the test results are listed in Table 7 .

The battery internal resistance AC impedance test result of table 7 embodiment and comparative example

The internal resistance test results during the battery cycle show that the internal resistance of the lithium-ion battery prepared in the present disclosure is smaller than that of the lithium-ion battery prepared in the comparative example during the cycle. The main reason is that the additives in the disclosure can form a solid interface film on the surface of the positive pole piece, and the lithium ion battery prepared in the disclosure has lower internal resistance and has certain application potential.

(2) Battery cycle performance test method: Lithium-ion batteries are charged and discharged in a blue electric battery charge and discharge test cabinet. The test conditions are 25°C, 0.5C/0.5C charge and discharge. The test results are listed in Table 8.

The battery cycle performance test result of table 8 embodiment and comparative example

The test results of the cycle performance of the examples and the comparative examples show that the battery capacity retention rate of the lithium-ion batteries prepared in the examples of the present disclosure is higher than that of the lithium-ion batteries prepared in the comparative examples during the cycle. The main reason is that the additives of the present disclosure can form a solid interface film on the surface of the positive electrode sheet, which is different from the solid interface film on the surface of the conventional positive electrode sheet, and has high polymer content, high-speed lithium conduction, good stability, etc. features. As the lithium-ion battery is charged and discharged, the unstable components in the solid interface on the surface of the positive electrode are gradually dissolved and continuously generated, and more new interfaces are formed on the positive electrode interface, which continue to consume electrolyte and lithium salt, and continue to form a solid interface film , the internal resistance of the battery continues to increase, and the performance of the battery declines sharply. In the present disclosure, due to the addition of the additive, it can form a solid interface film with a more stable molecular structure and higher lithium-conducting performance on the surface of the positive electrode sheet, which can improve the cycle performance of the battery.

Example 13

In this embodiment, the electrolyte includes the additive.

1) Preparation of positive pole piece:

Mix 97g positive electrode active material lithium cobaltate, 1g binder polyvinylidene fluoride (PVDF), 1g conductive carbon black, 1g conductive carbon nanotubes, add 400g N-methylpyrrolidone (NMP), in a vacuum mixer Stir under the action until the mixed system becomes a positive electrode slurry with uniform fluidity; the positive electrode slurry is evenly coated on an aluminum foil with a thickness of 12 μm; after drying at 100 ° C for 36 hours, the electrode sheet is obtained after vacuum treatment, and The pole piece is rolled and cut to obtain the positive pole piece;

2) Preparation of negative pole piece:

5g silicon oxide, 87g graphite, 2g conductive agent single wall carbon nanotube (SWCNT), 2g conductive agent conductive carbon black (SP), 2g binder sodium carboxymethyl cellulose (CMC), 2g binder D Styrene rubber (SBR), 300g deionized water, made into slurry by wet process, coated on the surface of negative electrode current collector copper foil, obtained negative electrode pole piece through drying, rolling and die-cutting;

3) Electrolyte preparation:

In a glove box filled with argon gas with qualified water and oxygen content, mix 25g of ethylene carbonate, 15g of propylene carbonate, 10g of diethyl carbonate, and 50g of n-propyl propionate evenly in proportion, and add 0.01g of fully dried dipropylene glycol The diacrylate is mixed evenly, and then 1.2mol/L of fully dried lithium hexafluorophosphate (LiPF ₆ ) is quickly added therein, and the electrolyte is prepared by stirring evenly;

4) Preparation of lithium ion battery

The positive pole piece and the negative pole piece obtained above are prepared into lithium-ion battery cells, and after liquid injection, packaging and welding, a lithium-ion battery is obtained.

Comparative example 13.1

Refer to Example 13 for the specific process of Comparative Example 13.1. The main difference is that dipropylene glycol dipropionate of the same mass and molecular weight as dipropylene glycol diacrylate is added to the electrolyte of Comparative Example 13.1, and other conditions are consistent with Example 13.

Comparative example 13.2

The specific process of Comparative Example 13.2 refers to Example 13, the main difference is that no dipropylene glycol diacrylate is added to the electrolyte of Comparative Example 13.2, and other conditions are consistent with Example 13.

For the specific processes of Examples 14-18 and other comparative examples, refer to Example 13. The main difference is the electrolyte formula. See Table 9 and Table 10 for details.

The composition of the electrolytic solution of table 9 embodiment and comparative example

The composition of the electrolytic solution of table 10 embodiment and comparative example

serial number

additive

serial number

additive

Example 13	Dipropylene glycol diacrylate	Example 16	1,3-Butanediol diacrylate
Comparative example 13.1	Dipropylene glycol dipropionate	Comparative example 16.1	1,3-Butanediol dipropionate
Comparative example 13.2	-----	Comparative example 16.2	----
Example 14	2,2',2"-Nitrotriethanol trimethacrylate	Example 17	triallyl isocyanurate
Comparative example 14.1	2,2',2"-Nitrotriethanol trimethylpropionate	Comparative example 17.1	Tripropylisocyanurate
Comparative example 14.2	----	Comparative example 17.2	---
Example 15	Triallyl trimesate	Example 18	dipentaerythritol pentaacrylate
Comparative example 15.1	Tripropyl trimesate	Comparative example 18.1	dipentaerythritol pentapropionate
Comparative example 15.2	----	Comparative example 18.2	----

Carry out performance test to the battery that above-mentioned embodiment and comparative example prepare:

(1) AC impedance test method of battery internal resistance: Use Metrohm PGSTAT302N chemical workstation in the range of 100KHz-0.1mHz, 25°C to conduct AC impedance test on 50% SOC lithium-ion battery, the test results are listed in Table 11 .

The battery internal resistance AC impedance test result of table 11 embodiment and comparative example

The internal resistance test results during the battery cycle show that the internal resistance of the lithium ion battery prepared in the embodiment of the present disclosure is smaller than that of the lithium ion battery prepared in the comparative example during the cycle process.

(2) Battery cycle performance test method: Lithium-ion batteries are charged and discharged on a blue battery charge and discharge test cabinet. The test conditions are 25°C, 0.5C/0.5C charge and discharge. The test results are listed in Table 12.

The battery cycle performance test result of table 12 embodiment and comparative example

The cycle performance test results of the examples and the comparative examples show that the capacity retention rate of the lithium-ion batteries prepared in the examples of the present disclosure is higher than that of the lithium-ion batteries prepared in the comparative examples during the cycle. The main reason is that the additives in the present disclosure can form an interface film on the surface of the positive and negative electrodes, which is different from the interface film on the surface of the conventional electrode, and has the characteristics of good electrochemical stability, high-speed lithium conduction, and large molecular weight. In the present disclosure, due to the addition of additives, a more stable interfacial film can be formed on the surface of the pole piece, improving the cycle performance of the battery.

The test results of the above-mentioned examples and comparative examples show that the lithium-ion battery prepared by the present disclosure has a small internal resistance during the cycle, and the lithium ion has a good lithium-conducting conductive channel, and the prepared lithium-ion battery has a good cycle. performance, with good application potential.

The embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above-mentioned embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.

Claims (15)

1. A secondary battery, the secondary battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte; it is characterized in that at least one of the positive electrode sheet, the negative electrode sheet, or the electrolyte includes an additive , the additive is selected from monomeric compounds including two or more carbon-carbon double bond structures.
2. The secondary battery according to claim 1, characterized in that the secondary battery comprises a negative electrode sheet, and the negative electrode sheet includes a negative electrode current collector and a negative active electrode coated on one or both sides of the negative electrode current collector. A material layer, the negative electrode active material layer includes a negative electrode active material, a conductive agent, a binder and the additive.
3. The secondary battery according to claim 1 or 2, characterized in that the secondary battery includes an electrolytic solution, and the additive is included in the electrolytic solution.
4. The secondary battery according to any one of claims 1-3, characterized in that the secondary battery comprises a positive pole piece, the positive pole piece comprises a positive current collector and is coated on one or both sides of the positive current collector. A positive electrode active material layer on the side surface, the positive electrode active material layer includes a positive electrode active material, a conductive agent, a binder and the additive.
5. The secondary battery according to any one of claims 1-4, wherein the additive is selected from monomer compounds having a structure shown in Formula 1:

   

   In formula 1, R ₁ is the same or different, independently selected from H or organic functional groups;

   R ₂ are the same or different, independently selected from H or organic functional groups;

   R ₃ are the same or different, independently selected from H or organic functional groups;

   R ₄ are the same or different, independently selected from nonexistent or linking groups;

   _R is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted ether, substituted or unsubstituted alicyclic, substituted or unsubstituted alicyclic-alkyl, substituted or unsubstituted alkyl-alicyclic-alkyl, substituted or unsubstituted cycloalkyl containing heterocyclic atoms, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted cycloalkenyl containing heterocyclic atoms, substituted or unsubstituted (hetero)aryl, substituted or unsubstituted alkenyl-aryl-alkenyl, substituted or unsubstituted (hetero)aryl-alkylene-(hetero)aryl, substituted or unsubstituted (hetero)aryl-O-(hetero)aryl, substituted or unsubstituted (hetero)aryl-S-(hetero)aryl, substituted or unsubstituted alkoxy-(hetero)arylylene-aryl Alkyl-(hetero)arylylene-O-alkyl, *-Sn(substituted or unsubstituted alkyl) ₂ -*, substituted or unsubstituted alkyl-OP(=O)(OH)-O- Alkyl, substituted or unsubstituted alkyl-OP(=O)(halogen)-O-alkyl, substituted or unsubstituted alkyl-OP(=O)(alkyl)-O-alkyl, substituted or Unsubstituted alkyl-OP(=O)(O-alkyl)-O-alkyl, substituted or unsubstituted P(O-alkyl), substituted or unsubstituted isocyanurate (alkoxy ) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted isocyanurate (alkyl) _n1 (n1 can be 0, 1, 2 or 3), substituted or unsubstituted N( Alkyl) ₃ , substituted or unsubstituted (alkyl) _n2 Si (O-Si (alkyl) (alkyl)) _n3 (n2, n3 are integers from 0 to 4 and n2+n3=4), substituted or Unsubstituted (alkyl) _n4 Si(O-alkyl) _n5 (n4, n5 are integers from 0 to 4 and n4+n5=4); when there is substitution, the substitution can be one or more, more They can be the same or different, and the substituted groups are selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si (Alkyl) ₃ , *-OP(=O)(OH) ₂ ;

   * indicates the connection end;

   n is an integer greater than or equal to 2.
6. The secondary battery according to claim 5, wherein the n is an integer of 2 to 6;

   Preferably, R ₄ are the same or different, independently of each other selected from the group consisting of absence or *-C(R')-O-**, *-C(=O)-O-**, *-C(=O )-S-**, *-C(R')2-OC(=O)-**, R's are the same or different, independently selected from H or alkyl; wherein, * represents the connection with the double bond terminal, ** represents the connection terminal with _R5 ;

   Preferably, R _are the same or different, independently selected from H, alkyl or cyano (-CN);

   Preferably, R ₂ are the same or different, independently selected from H, alkyl or aryl;

   Preferably, R ₃ are the same or different, independently selected from H, alkyl or aryl;

   Preferably, R _is selected from substituted or unsubstituted C _1-20 alkyl, *-CH(R")-CH(R")-O-[CH(R")-CH(R")-O] _n6 -CH(R")-CH(R")-*(n6=0, 1, 2..., R" is H or alkyl), substituted or unsubstituted C _1-6 alkyl-C _5-10 Cycloalkyl-C _1-6 alkyl, substituted or unsubstituted adamantyl, chlorenic acid, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted phenyl- Alkyl-phenyl, substituted or unsubstituted phenyl-O-phenyl, substituted or unsubstituted phenyl-S-phenyl, substituted or unsubstituted C _1-6 alkyl-O-phenyl- Alkyl-phenyl-OC _1-6 alkyl, fluorescein, *-Sn(C _1-6 alkyl) ₂ -*, substituted or unsubstituted C _1-6 alkyl-OP(=O)(OH )-OC _1-6 alkyl, substituted or unsubstituted vinyl-phenyl-vinyl, substituted or unsubstituted isocyanurate (alkoxy) n1 (n1 can be 0, 1, 2 or 3 ), substituted or unsubstituted isocyanuric acid group (C _1-6 alkyl) _n1 (n1 can be 0, 1, 2 or 3); when there is substitution, the substitution can be one or more, more They can be the same or different, and the substituted groups are selected from halogen, -OH, alkyl-OC(=O)-*, alkyl-C(=O)-O-*, *-O-Si (Alkyl) ₃ , *-OP(=O)(OH) ₂ .
7. The secondary battery according to any one of claims 5-6, wherein the additive is selected from at least one of the compounds having the structure shown in formula 2:

   
8. The secondary battery according to any one of claims 5-7, wherein the additive is selected from formula 2-1, formula 2-2, formula 2-3, formula 2-4, formula 2-5 At least one of the compounds of the shown structure:

   
9. The secondary battery according to any one of claims 5-6, wherein the additive is selected from at least one of the compounds having the structure shown in formula 3:

   
10. The secondary battery according to any one of claims 5-6, wherein the additive is selected from at least one of the compounds having the structure shown in formula 4:

    
11. The secondary battery according to any one of claims 5-6, wherein the additive is selected from at least one of the compounds having the structure shown in formula 5:

    
12. The secondary battery according to any one of claims 1-11, wherein the additive is selected from at least one of the following compounds: 1,5-pentanediol diacrylate (CAS number: 36840-85 -4), pentaerythritol tetraacrylate (CAS number: 4986-89-4), 1,6-hexanediol dimethacrylate (CAS number: 6606-59-3), 1,4-butanediol dimethacrylate Methacrylate (CAS No.: 2082-81-7), Triethylene Glycol Dimethacrylate (CAS No.: 109-16-0), 1,4-Butanediol Diacrylate (CAS No.: 1070 -70-8), triethylene glycol diacrylate (CAS No.: 1680-21-3), tripropylene glycol diacrylate (CAS No.: 42978-66-5), 1,10-decanediol diacrylate Acrylates (CAS No.: 13048-34-5), Diethylene Glycol Dimethacrylate (CAS No.: 2358-84-1), Neopentyl Glycol Diacrylate (CAS No.: 2223-82-7) , Ethylene glycol dimethacrylate (CAS number: 97-90-5), 1,3-butanediol dimethacrylate (CAS number: 1189-08-8), tetraethylene glycol dimethyl Acrylate (CAS No.: 109-17-1), Tetraethylene glycol diacrylate (CAS No.: 17831-71-9), Fluorescein O,O'-diacrylate (CAS No.: 7262-39-7) , bisphenol A dimethacrylate (CAS number: 3253-39-2), 3-allyloxypropyl methacrylate (CAS number: 77757-02-9), bisphenol A diacrylate ( CAS No.: 4491-03-6), tris(2-acryloyloxyethyl) isocyanurate (CAS No.: 67893-00-9), 2,2,6,6-tetrabromobisphenol A di Acrylates (CAS No.: 55205-38-4), 1,3-Propanediol Dimethacrylate (CAS No.: 7559-82-2), Cyclohexanedimethanol Diacrylate (CAS No.: 67905-41- 3), Cyclohexanedimethanol dimethacrylate (CAS No.: 52892-97-4), 2-[(trimethylsilyl)oxy]-1,3-propanediylbis(2-methyl) Acrylate) (CAS No.: 247244-66-2), glycerol trimethacrylate (CAS No.: 7401-88-9), 2-butene-1,4-dimethacrylate (CAS No.: 18621-77-7), 2,2',2"-nitrilotriethanol trimethacrylate (CAS No.: 13884-43-0), 2,2,6,6-tetrabromobisphenol A di Methacrylate (CAS No.: 42146-13-4), 1-methyl-1,2-ethanediyl diacrylate (CAS No.: 25151-33-1), 2-(phosphoryloxy)propane -1,3-diyl dimethacrylate (CAS No.: 67829-13-4), dibutyltin dimethacrylate (CAS No.: 15257-25-7), sorbitol pentaacrylate ( CAS No.: 53123-67-4), 3-methyl-1,5-pentanediyl diacrylate (CAS No.: 64194-22-5), 1,2,3-propanetriyl triacrylate ( CAS No.: 5459-38-1), pentaerythritol tetrakis (2-cyano-3,3-diphenylacrylate) (CAS No.: 178671-58-4), neopentyl glycol dimethacrylate (CAS No. : 1985-51-9), diethylene glycol diacrylate (CAS No.: 4074-88-8), dipropylene glycol diacrylate (CAS No. 57472-68-1), 1,3-butylene diacrylate Alcohol Esters (CAS No.: 19485-03-1), 1,3-Adamantyl Dimethacrylate (CAS No.: 122066-43-7), Bis(4-Methacryloylthiophenyl) Sulfide (CAS No.: 129283-82-5), Ethylene Glycol Diacrylate (CAS No.: 2274-11-5), Dipentaerythritol Pentaacrylate (CAS No.: 60506-81-2), Ethoxylated Bisphenol A Acrylic diester (CAS No.: 41637-38-1), tris(2-acryloyloxyethyl) isocyanurate (CAS No.: 40220-08-4), diallyl phthalate ( CAS No.: 131-17-9), Triallyl Trimellitate (CAS No.: 17832-16-5), Diallyl-N-Propyl Isocyanurate (CAS No.: 5320-25-2) , Diallyl Allyl Phosphonate (CAS No.: 3479-30-9), Triallyl Phosphate (CAS No.: 1623-19-4), Diallyl Metaphthalate (CAS No. : 1087-21-4), Triallyl 1,2,4-benzenetricarboxylate (CAS No.: 2694-54-4), Triallyl Phosphite (CAS No.: 102-84-1), Tetraallyl silicate (CAS No.: 1067-43-2), diallyl chlorophosphate (CAS No.: 16383-57-6), diallyl chlorendate (CAS No.: 3232- 62-0), diallyl azelate (CAS number: 3136-99-0), triallyl citrate (CAS number: 6299-73-6), diallyl malate ( CAS No.: 32099-14-2), diallyl isocyanurate (CAS No.: 6294-79-7), diethyl 1,4-benzenediacrylate (CAS No.: 17088-28-7) , Diethyl Diallyl Malonate (CAS No.: 3195-24-2), Dimethyl Diallyl Malonate (CAS No.: 35357-77-8), Triallyl Isocyanurate ester (CAS No.: 1025-15-6), ethyl 1,1,1-trimethylol triacrylate (CAS No.: 19778-85-9), diallyl isocyanurate (CAS No.: 1081- 69-2), Diallyl 1,4-cyclohexanedicarboxylate (CAS No.: 20306-22-3), 2,2,3,3,4,4-hexafluoro-1,5-diacrylic acid Amyl ester (CAS No.: 678-95-5), 1,4-phenylene diacrylate (CAS No.: 6729-79-9), diallyl naphthalene-2,3-dicarboxylate (CAS No. : 52640-63-8), 3-(2-methylprop-2-enoyloxy)propyl 2-methylprop-2-enoate (CAS No.: 1188-09-6), trimethyl trimethylolpropyl acrylate (CAS No.: 102068-89-3), bis(methacryloyloxyethyl) phosphate (CAS No.: 32435-46-4), 1,1,1-tri Methanol ethyl trimethacrylate (CAS number: 24690-33-3), pentaerythritol tetramethacrylate (CAS number: 118541-94-9), neopentyl glycol 2,2-dibromodiacrylate (CAS No.: 41223-11-4), neopentyl glycol dimethacrylate (CAS No.: 104182-97-0), 2-methyl-2-propionic acid-1,1-[oxybis(methyl -2,1-Ethanediyl)]ester (CAS No.: 64111-89-3), Methacryloyloxypropyltris(vinyldimethylsiloxy)silane (CAS No.: 17096-10- 5) Dipropylene phthalate (CAS No.: 131-17-9), 2,2',2"-nitrilotriethanol trimethacrylate (CAS No.: 13884-43-0).
13. The secondary battery according to any one of claims 1-12, characterized in that the electrolyte contains the additive, and the content of the additive accounts for 0.01wt%-5wt% of the total mass of the electrolyte.
14. The secondary battery according to any one of claims 1-13, wherein the additive is in the negative electrode active material layer of the negative electrode sheet, and the content of the additive accounts for the mass of the total mass of the negative electrode active material layer The percentage content is 0.001wt% ~ 2wt%;

    Preferably, the additive is in the positive electrode active material layer of the positive electrode sheet, and the content of the additive is 0.001wt%-1.0wt% in mass percent based on the total mass of the positive electrode active material layer.
15. The secondary battery according to any one of claims 1-14, characterized in that the secondary battery is a lithium ion battery.