Cylindrical lithium-ion battery

Abstract

The present application provides a cylindrical lithium-ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The negative electrode comprises a negative electrode material layer containing a negative electrode active material, and the negative electrode active material comprises a silicon-based material; the non-aqueous electrolyte comprises a non-aqueous organic solvent and a lithium salt, the non-aqueous organic solvent comprises chain carbonate containing DMC, and the lithium salt comprises LiPF6 and lithium fluorosulfonyl imide; the cylindrical lithium-ion battery satisfies the following condition: 0.05≤(100-D)*F / S≤8.75, wherein 50≤D≤75, 0.012≤F≤1, and 5≤S≤20. According to the present application, the mass percentage D of DMC in the non-aqueous electrolyte, the molar content ratio F of lithium fluorosulfonyl imide to LiPF6 in the non-aqueous electrolyte and the mass percentage S of silicon in the negative electrode material layer are controlled to satisfy the following condition: 0.05≤(100-D)*F / S≤8.75, wherein 50≤D≤75, 0.012≤F≤1, and 5≤S≤20, such that the rate performance, the normal-temperature cycle performance, and the high-temperature storage performance of the cylindrical lithium-ion battery can be effectively improved, thereby prolonging the service life.

Description

A cylindrical lithium-ion battery Technical Field

[0001] The present application belongs to the technical field of secondary batteries, and specifically relates to a cylindrical lithium-ion battery. Background Art

[0002] Cylindrical batteries have the advantages of simple design, standard manufacturing, simple process, low cost and strong application flexibility, and are therefore favored by major manufacturers. Traditional cylindrical batteries do not have an advantage as power batteries due to their small size. To address this problem, existing cylindrical batteries are becoming larger and larger, with the diameter of cylindrical batteries increasing to 46mm, which has further increased the energy density of cylindrical battery cells. Because the pole pieces of cylindrical batteries are wound in a coiled design, the tension of the winding after the pole pieces are wound layer by layer can effectively suppress the expansion of the pole pieces, making them more suitable for silicon negative electrodes that expand significantly after charging and discharging. The cell design of cylindrical batteries is suitable for high-energy-density material systems.

[0003] Silicon-containing anodes experience a significant volume effect. The lithium-silicon alloying and dealloying processes are accompanied by dramatic expansion and contraction of the anode, causing the solid electrolyte interface (SEI) film on its surface to constantly rupture and regenerate, leading to electrolyte consumption and loss of active lithium. This increases interfacial impedance, thus deteriorating cycle performance. Furthermore, as charge and discharge progress, the thickness of the anode plate increases, squeezing the battery's protective casing, potentially causing it to rupture and pose a safety hazard. Furthermore, the increased thickness impairs contact between the active material and the copper foil current collector, affecting electronic conductivity and causing a sharp decline in battery capacity in the later stages of the cycle, resulting in a "diving" phenomenon.

[0004] Currently, the industry's approach to increasing the energy density of cylindrical batteries is mostly achieved by using high-capacity cathode and anode materials. Silicon-based anodes have a theoretical capacity approximately 10 times that of currently used graphite anodes. Therefore, increasing the silicon content in the anode material of battery cells is a key development direction for achieving higher energy density. For every 10% increase in energy density, cycle life decreases by 25%. Battery cells made with high-energy-density materials suffer from a cycle life shortcoming, making it difficult to increase the cycle life of existing cylindrical batteries while maintaining high energy density.

[0005] Therefore, it is necessary to develop a cylindrical lithium ion battery to solve the above problems existing in the prior art.

[0006] Summary of the Invention

[0007] Based on this, the purpose of this application is to provide a cylindrical lithium-ion battery, which has the advantages of high energy density, good room temperature cycle performance and good high temperature storage performance.

[0008] To achieve the above object, the present application adopts the following technical solutions.

[0009] A cylindrical lithium-ion battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte; the negative electrode includes a negative electrode material layer containing a negative electrode active material, and the negative electrode active material includes a silicon-based material; the non-aqueous electrolyte includes a non-aqueous organic solvent and a lithium salt, the non-aqueous organic solvent includes a chain carbonate containing DMC, and the lithium salt includes LiPF6 and lithium fluorosulfonylimide;

[0010] The cylindrical lithium-ion battery satisfies the following conditions:

[0011] 0.05 ≤ (100 - D)*F / S ≤ 8.75, and 50 ≤ D ≤ 75, 0.012 ≤ F ≤ 1, 5 ≤ S ≤ 20;

[0012] Where, D is the mass percentage content of DMC in the non-aqueous electrolyte, with the unit of wt%;

[0013] F is the ratio of the molar content of lithium fluorosulfonylimide to the molar content of LiPF6 in the non-aqueous electrolyte;

[0014] S is the mass percentage content of silicon element in the negative electrode material layer, with the unit of wt%.

[0015] Optionally, the cylindrical lithium-ion battery satisfies the following condition: 0.1 ≤ (100 - D)*F / S ≤ 7.5.

[0016] Optionally, the mass percentage content D of DMC in the non-aqueous electrolyte is 55wt% - 67wt%.

[0017] Optionally, the ratio F of the molar content of lithium fluorosulfonylimide to the molar content of LiPF6 in the non-aqueous electrolyte is 0.06 - 0.85.

[0018] Optionally, the mass percentage content S of silicon element in the negative electrode material layer is 7wt% - 15wt%.

[0019] Optionally, the silicon-based material is selected from one or more of silicon materials, silicon oxide materials, silicon-carbon composite materials, and silicon alloy materials; preferably, the negative electrode active material is selected from silicon-carbon composite materials;

[0020] Preferably, the silicon material is a nanosilicon material; the silicon oxide material is a SiOx material, where 0 < x < 2; the silicon-carbon composite material is a silicon-based material containing silicon and carbon materials, and / or a silicon-based material containing SiOy and carbon materials, where 0 < y < 2; the silicon alloy material is a Mg2Si alloy material and / or an Fe2Si alloy material.

[0021] Optionally, the lithium fluorosulfonyl imide is selected from one or more of LiFSI and LiTFSI.

[0022] Optionally, the lithium salt further comprises LiBOB, LiDFOB, LiDFOP, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiClO4, LiAlCl4, LiCF3SO3, LiSO3F, Li2B 10 Cl 10 , one or more of lithium chloroborane, lithium tetrafluorooxalophosphate, lithium trioxalophosphate, a lower aliphatic lithium carboxylate having 4 or less carbon atoms, or lithium tetraphenylborate.

[0023] Optionally, the total molar content of the lithium salt is 0.9 mol / L to 3.5 mol / L, and 0.012≤F≤1; preferably, the total molar content of the lithium salt is 1.1 mol / L to 1.5 mol / L, and 0.06≤F≤0.85.

[0024] Optionally, the non-aqueous organic solvent further comprises one or more of cyclic carbonates, carboxylates and ethers;

[0025] Preferably, the cyclic carbonate is selected from one or more of ethylene carbonate, fluoroethylene carbonate, vinylene carbonate, propylene carbonate and butylene carbonate;

[0026] The chain carbonate further comprises one or more of diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate;

[0027] The carboxylate is selected from one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, methyl isobutyrate, ethyl butyrate, pivalic acid methyl ester and pivalic acid ethyl ester;

[0028] The ethers are selected from one or more of ethylene glycol dimethyl ether, 1,3-dioxolane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0029] Optionally, the non-aqueous electrolyte further comprises an additive, wherein the additive is selected from one or more of cyclic carbonate compounds, cyclic sulfate compounds, sultone compounds, phosphate compounds, borate compounds, and nitrile compounds; and the content of the additive is 0.01% to 30% based on the total mass of the non-aqueous electrolyte as 100%;

[0030] Preferably, the cyclic carbonate compound is selected from one or more of vinylene carbonate, ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethylethylene carbonate, bisfluoroethylene carbonate or the compound represented by the following structural formula 1:

[0031] In the structural formula 1, R 21 、R 22 、R 23 、R 24 、R 25 、R 26 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group;

[0032] The cyclic sulfate compound is selected from one or more of vinyl sulfate, 4-methylvinyl sulfate, and propylene sulfate;

[0033] The sultone compound is selected from one or more of 1,3-propane sultone, 1,4-butane sultone, and propenyl-1,3-sultone;

[0034] The phosphate compound is selected from tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate and the compound shown in the following structural formula 2:

[0035] In the structural formula 2, R 31 、R 32 、R 33 Each independently selected from C1-C5 saturated hydrocarbon group, unsaturated hydrocarbon group, halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 、R 32 、R 33 At least one of them is an unsaturated hydrocarbon group;

[0036] The borate compound is selected from one or more of tris(trimethylsilyl)borate and tris(triethylsilyl)borate;

[0037] The nitrile compound is selected from one or more of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile and sebacononitrile.

[0038] This application provides a cylindrical lithium-ion battery whose negative electrode active material comprises a silicon-based material and whose non-aqueous electrolyte utilizes a non-aqueous organic solvent comprising DMC and a lithium salt comprising LiPF6 and lithium fluorosulfonyl imide. For lithium-ion batteries with high energy density and silicon-containing negative electrodes, selecting DMC as the electrolyte non-aqueous organic solvent can significantly improve the wettability and fluidity of the non-aqueous electrolyte; selecting lithium fluorosulfonyl imide and LiPF6 as the lithium salt can enhance conductivity, electrochemical properties, thermal stability, and hydrolysis resistance. Based on their own experience and extensive research, the inventors found that when the mass percentage D of DMC in the non-aqueous electrolyte, the ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte, and the mass percentage S of silicon element in the negative electrode material layer satisfy 0.05≤(100-D)*F / S≤8.75, and 50≤D≤75, 0.012≤F≤1, 5≤S≤20, the volume change of the silicon negative electrode can be effectively suppressed, and the problems of electrolyte consumption and active lithium loss, increased interfacial impedance, deterioration of cycle performance, and rapid attenuation of battery capacity in the late cycle can be improved, thereby improving the rate performance, room temperature cycle performance, and ultra-high temperature storage performance of the cylindrical lithium-ion battery and increasing its service life. DETAILED DESCRIPTION

[0039] The experimental methods in the following examples of this application, where specific conditions are not specified, are generally carried out under conventional conditions or conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product, or device comprising a series of steps is not limited to the listed steps or modules but may optionally include steps not listed, or other steps inherent to the process, method, product, or device.

[0042] The term "plurality" used in this application refers to two or more types.

[0043] This embodiment provides a cylindrical lithium-ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte; the negative electrode comprises a negative electrode material layer containing a negative electrode active material, wherein the negative electrode active material comprises a silicon-based material; the non-aqueous electrolyte comprises a non-aqueous organic solvent and a lithium salt, wherein the non-aqueous organic solvent comprises a chain carbonate containing DMC, and the lithium salt comprises LiPF6 and lithium fluorosulfonyl imide;

[0044] The cylindrical lithium-ion battery meets the following conditions:

[0045] 0.05≤(100-D)*F / S≤8.75, and 50≤D≤75, 0.012≤F≤1, 5≤S≤20;

[0046] Wherein, D is the mass percentage of DMC in the non-aqueous electrolyte, in wt%;

[0047] F is the ratio of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte;

[0048] S is the mass percentage of silicon element in the negative electrode material layer, in wt%.

[0049] The cylindrical lithium-ion battery provided herein has a negative electrode active material comprising a silicon-based material, and a non-aqueous electrolyte comprising a non-aqueous organic solvent comprising DMC (dimethyl carbonate) and a lithium salt comprising LiPF6 and lithium fluorosulfonyl imide. For lithium-ion batteries with high energy density and silicon-containing negative electrodes, selecting DMC as the electrolyte non-aqueous organic solvent can significantly improve the wettability and fluidity of the non-aqueous electrolyte; selecting lithium fluorosulfonyl imide and LiPF6 as the lithium salt can enhance conductivity, electrochemical properties, thermal stability, and hydrolysis resistance. Based on their own experience and extensive research, the inventors found that when the mass percentage D of DMC in the non-aqueous electrolyte, the ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte, and the mass percentage S of silicon element in the negative electrode material layer meet 0.05≤(100-D)*F / S≤8.75, and 50≤D≤75, 0.012≤F≤1, 5≤S≤20, the volume change of the silicon negative electrode can be effectively suppressed, and the problems of electrolyte consumption and active lithium loss, increased interfacial impedance, deterioration of cycle performance, and rapid attenuation of battery capacity in the late cycle can be improved, thereby improving the rate performance, room temperature cycle performance, and ultra-high temperature storage performance of the cylindrical lithium-ion battery and increasing its service life.

[0050] Specifically, the value of (100-D)*F / S can be, but is not limited to, 0.05, 0.07, 0.09, 0.1, 1.2, 1.5, 1.6, 1.8, 2, 2.1, 2.3, 2.5, 2.7, 3, 3.2, 3.6, 3.8, 4, 4.2, 4.5, 4.7, 5, 5.4, 5.6, 5.8, 6, 6.2, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.5, 7.8, 8.0, 8.2, 8.5, 8.75.

[0051] In a preferred embodiment, the cylindrical lithium-ion battery satisfies the following condition: 0.1 ≤ (100-D) * F / S ≤ 7.5. Furthermore, 0.1 ≤ (100-D) * F / S ≤ 7.5 is preferably selected based on 0.05 ≤ (100-D) * F / S ≤ 8.75. This can better suppress the volume expansion of the silicon anode and improve the cycle performance and service life of the high-energy-density lithium-ion battery containing a silicon anode.

[0052] Specifically, the mass percentage D of DMC in the non-aqueous electrolyte can be, but is not limited to, 50wt%, 52wt%, 55wt%, 58wt%, 60wt%, 62wt%, 65wt%, 67wt%, 69wt%, 70wt%, 72wt%, 74wt%, or 75wt%.

[0053] In a preferred embodiment, the mass percentage D of DMC in the non-aqueous electrolyte is 55 wt % to 67 wt %.

[0054] Cylindrical batteries have a tightly wound structure, a compact material structure, and relatively little internal space. The premise for the electrolyte to function effectively is good wettability and fluidity. The viscosity of chain carbonates is lower than that of cyclic carbonates, and DMC has the lowest viscosity among commonly used non-aqueous organic solvents. Correspondingly, it has the best effect on improving conductivity. However, DMC is prone to produce gas in high-temperature environments, and the amount used also needs to be controlled. Using 50wt% to 75wt% of DMC as a non-aqueous organic solvent component in the non-aqueous electrolyte can greatly improve the wettability and fluidity of the non-aqueous electrolyte. In particular, when the mass percentage D of DMC is 55wt% to 67wt%, the wettability and fluidity of the non-aqueous electrolyte of this application can be better improved.

[0055] Silicon-based anodes lack the conductivity of graphite. Compared to LiPF6, lithium fluorosulfonyl imide (LFIM) in non-aqueous electrolytes offers superior conductivity, electrochemical and thermal stability, and hydrolysis resistance, helping to reduce battery internal resistance, minimize heat generation, improve discharge efficiency, and enhance battery safety. However, high LFIM levels can easily cause aluminum foil corrosion. Therefore, adjusting the LFIM to LiPF6 molar ratio (F) in the non-aqueous electrolyte to 0.012–1 can largely mitigate this issue. In particular, adjusting F to 0.06–0.85 achieves a better balance in battery performance. When reducing the mass fraction (D) of DMC in the non-aqueous electrolyte to increase the (100-D) ratio, the LFIM to LiPF6 molar ratio (F) must be adjusted to ensure sufficient system conductivity. Furthermore, introducing an appropriate amount of LFIM into a silicon-based cylindrical system can further optimize battery rate performance, extend cycle life, and enhance high-temperature stability.

[0056] Specifically, the mass percentage content S of silicon element in the negative electrode material layer may be, but is not limited to, 5wt%, 7wt%, 9wt%, 10wt%, 12wt%, 14wt%, 15wt%, 17wt%, 19wt%, 20wt%.

[0057] Silicon-based materials can effectively improve the energy density of the battery, but their huge volume effect cannot be ignored. Especially as the silicon content increases, this negative impact will increase exponentially. The high-strength shell of cylindrical batteries can, to a certain extent, inhibit the decomposition of electrolytes to generate gas and the damage of the battery body caused by the volume expansion of materials. At the same time, through the coordinated regulation of the silicon content and key components in the electrolyte design, the volume effect can be further optimized: taking (100 - D) as the control parameter, coordinating with the change of the silicon content S to regulate the content of DMC (reducing the content and reducing the gas production pressure) and the value of F, taking into account the electrolyte compatibility of cylindrical batteries with different silicon contents.

[0058] In some embodiments, the silicon-based material is selected from one or more of silicon materials, silicon oxide materials, silicon-carbon composite materials, and silicon alloy materials.

[0059] In some embodiments, the silicon material is a nanosilicon material; the silicon oxide material is a SiOx material, where 0 < x < 2; the silicon-carbon composite material is a silicon-based material containing silicon and carbon materials, and / or a silicon-based material containing SiOy and carbon materials, where 0 < y < 2; the silicon alloy material is a Mg2Si alloy material and / or an Fe2Si alloy material.

[0060] Silicon materials have a high specific capacity, but due to their lithium insertion mechanism, they are prone to volume expansion, resulting in the rupture and failure of electrode materials; carbon materials are more stable than silicon materials. In some preferred embodiments, the negative electrode active material is selected from silicon-carbon composite materials. The silicon and carbon in the silicon-carbon composite material form a complementary relationship. The high specific capacity of the silicon-based and the cyclic stability of the carbon-based are combined, which can effectively solve the problem of material expansion and failure, while taking into account good cyclic performance.

[0061] Specifically, the ratio F of the molar content of lithium fluorosulfonylimide to the molar content of LiPF6 in the non-aqueous electrolyte may be, but is not limited to, 0.012, 0.05, 0.06, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.

[0062] In a preferred embodiment, the molar content of lithium fluorosulfonyl imide in the non-aqueous electrolyte is 0.01 mol / L to 0.9 mol / L; more preferably, the molar content of lithium fluorosulfonyl imide in the non-aqueous electrolyte is 0.1 mol / L to 0.6 mol / L.

[0063] In a preferred embodiment, the molar content of LiPF6 in the non-aqueous electrolyte is 0.5 mol / L to 2.0 mol / L; more preferably, the molar content of LiPF6 in the non-aqueous electrolyte is 0.6 mol / L to 1.3 mol / L.

[0064] In a preferred embodiment, the lithium fluorosulfonyl imide is selected from one or more of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI).

[0065] In some embodiments, the lithium salt further comprises LiBOB, LiDFOB, LiDFOP, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiClO4, LiAlCl4, LiCF3SO3, LiSO3F, Li2B 10 Cl 10 , one or more of lithium chloroborane, lithium tetrafluorooxalophosphate, lithium trioxalophosphate, a lower aliphatic lithium carboxylate having 4 or less carbon atoms, or lithium tetraphenylborate.

[0066] In some embodiments, the total molar content of the lithium salt is 0.9 mol / L to 3.5 mol / L, and 0.012≤F≤1; preferably, the total molar content of the lithium salt is 1.1 mol / L to 1.5 mol / L, and 0.06≤F≤0.85. Specifically, the total molar content of the lithium salt can be 0.9 mol / L, 0.95 mol / L, 1.0 mol / L, 1.1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.45 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3.0 mol / L, 3.1 mol / L, 3.2 mol / L, 3.3 mol / L, 3.4 mol / L or 3.5 mol / L.

[0067] In some embodiments, the non-aqueous organic solvent further comprises one or more of cyclic carbonates, carboxylates, and ethers.

[0068] Preferably, the cyclic carbonate is selected from one or more of ethylene carbonate, fluoroethylene carbonate (FEC), vinylene carbonate, propylene carbonate and butylene carbonate;

[0069] The chain carbonate further comprises one or more of diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate;

[0070] The carboxylate is selected from one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, methyl isobutyrate, ethyl butyrate, pivalic acid methyl ester and pivalic acid ethyl ester;

[0071] The ethers are selected from one or more of ethylene glycol dimethyl ether, 1,3-dioxolane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0072] In some preferred embodiments, the non-aqueous organic solvent includes a linear carbonate and a cyclic carbonate, with the cyclic carbonate comprising at least FEC. The FEC content is 6% to 30% based on the total mass of the non-aqueous electrolyte as 100%. In silicon-containing battery electrolytes, FEC not only facilitates interfacial film formation but also helps suppress lithium consumption.

[0073] In some embodiments, the non-aqueous electrolyte further includes an additive, and the additive is selected from one or more of cyclic carbonate compounds, cyclic sulfate compounds, sultone compounds, phosphate compounds, borate compounds, and nitrile compounds.

[0074] Preferably, the cyclic carbonate compound is selected from one or more of vinylene carbonate, ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethylethylene carbonate, bisfluoroethylene carbonate or the compound represented by the following structural formula 1:

[0075] In the structural formula 1, R 21 、R 22 、R 23 、R 24 、R 25 、R 26 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group;

[0076] The cyclic sulfate compound is selected from one or more of vinyl sulfate, 4-methylvinyl sulfate, and propylene sulfate;

[0077] The sultone compound is selected from one or more of 1,3-propane sultone, 1,4-butane sultone, and propenyl-1,3-sultone;

[0078] The phosphate compound is selected from tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate and the compound shown in the following structural formula 2:

[0079] In the structural formula 2, R 31 、R 32 、R 33 Each independently selected from C1-C5 saturated hydrocarbon group, unsaturated hydrocarbon group, halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 、R 32 、R 33 At least one of them is an unsaturated hydrocarbon group;

[0080] The borate compound is selected from one or more of tris(trimethylsilyl)borate and tris(triethylsilyl)borate;

[0081] The nitrile compound is selected from one or more of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile and sebacononitrile.

[0082] It should be noted that, unless otherwise specified, under normal circumstances, the content of any one of the optional substances in the additives in the non-aqueous electrolyte is less than 10%, preferably, the content is 0.1% to 5%, and more preferably, the content is 0.1% to 3%. Specifically, the content of any one of the optional substances in the additives can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0083] In some embodiments, the positive electrode includes a positive electrode material layer containing a positive electrode active material. The type and content of the positive electrode active material are not particularly limited and can be selected according to actual needs, as long as it is a positive electrode active material or a conversion-type positive electrode material that can reversibly embed / de-embed metal ions and lithium ions.

[0084] In some embodiments, the positive electrode active material may be selected from LiFe 1-x’ M' x’ PO4、LiMn 2-y’ My’ O4 and LiNi x Co y Mn z M 1-x-y-z At least one of O2, wherein M' is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, W, Zr, V or Ti, M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, W, Zr, V or Ti, and 0≤x'<1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1, the positive electrode active material can also be selected from at least one of sulfide, selenide, and halide. More preferably, the positive electrode active material can be selected from LiCoO2, LiFePO4, LiFe 0.4 Mn 0.6 PO4, LiMn2O4, LiNi 0.5 Co 0.2 Mn 0.3 O2、LiNi 0.6 Co 0.2 Mn 0.2 O2、LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.8 Co 0.15 Al 0.05 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi 0.5 Co 0.2 Mn 0.2 Al 0.1 O2、LiNi 0.5 Co 0.2 Al 0.3 At least one of O2.

[0085] In some embodiments, the positive electrode further includes a positive electrode current collector, and the positive electrode material layer is disposed on a surface of the positive electrode current collector.

[0086] The positive electrode current collector is selected from a metal material that can conduct electrons. Preferably, the positive electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive electrode current collector is selected from aluminum foil.

[0087] In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductor, and the positive electrode active material, the positive electrode binder and the positive electrode conductor are blended to obtain the positive electrode material layer.

[0088] The positive electrode binder includes polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-fluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, a thermoplastic resin such as polyethylene and polypropylene; an acrylic resin; and at least one of styrene butadiene rubber.

[0089] The positive electrode conductive agent includes at least one of conductive carbon black, conductive carbon balls, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene, or reduced graphene oxide.

[0090] In some embodiments, the negative electrode further comprises a negative electrode current collector, and the negative electrode material layer is disposed on the surface of the negative electrode current collector. The material of the negative electrode current collector can be the same as that of the positive electrode current collector, which will not be described in detail here.

[0091] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent. The negative electrode active material, the negative electrode binder, and the negative electrode conductive agent are blended together to form the negative electrode material layer. The negative electrode binder and the negative electrode conductive agent may be the same as the positive electrode binder and the positive electrode conductive agent, respectively, and are not further described here.

[0092] In some embodiments, the secondary battery further includes a separator, and the separator is located between the positive electrode and the negative electrode.

[0093] The diaphragm can be an existing conventional diaphragm, which can be a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, an inorganic-organic composite diaphragm, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP and three-layer PP / PE / PP diaphragms.

[0094] The following describes the details in conjunction with specific embodiments.

[0095] Example 1

[0096] This embodiment is used to illustrate the cylindrical lithium-ion battery and its preparation method disclosed in this application, including the following steps:

[0097] Preparation of positive electrode: Mix high nickel ternary positive electrode active material NCM811 (LiNi 0.8 Co 0.1 Mn 0.1O2), conductive carbon black and binder polyvinylidene fluoride are dispersed in N-methyl-2-pyrrolidone to obtain a positive electrode slurry, and the positive electrode slurry is evenly coated on both sides of the aluminum foil. After drying, rolling and vacuum drying, a positive electrode material layer is formed on the aluminum foil, and an aluminum lead wire is welded with an ultrasonic welder to obtain a positive electrode plate. The thickness of the plate is between 120-150 μm;

[0098] Preparation of the negative electrode: A silicon-carbon composite material (a mixture of silicon dioxide and graphite), conductive carbon black, a binder of styrene-butadiene rubber, and sodium carboxymethyl cellulose were mixed in a mass ratio of 94.2:1.2:3.0:1.5 and dispersed in deionized water to obtain a negative electrode slurry. The negative electrode slurry was coated on both sides of a copper foil. After drying, rolling, and vacuum drying, a negative electrode material layer (with a Si content of 6%) was formed on the copper foil. Nickel lead wires were welded to the negative electrode plate using an ultrasonic welder. The thickness of the plate was between 120 and 150 μm.

[0099] Preparation of electrolyte: Dimethyl carbonate (DMC), ethylene carbonate (EC) and fluoroethylene carbonate (FEC) were mixed in a certain mass ratio, and then LiFSI and LiPF6 were added. The mass percentages of DMC and FEC in the electrolyte were 75% and 10%, respectively. The molar contents of LiFSI and LiPF6 are shown in Table 1.

[0100] Battery assembly: A separator is placed between the positive and negative plates, and the sandwich structure consisting of the positive, negative and separator plates is wound, and the wound body is placed in a cylindrical aluminum metal shell.

[0101] Injection and formation: The prepared electrolyte was injected into the cell, vacuum sealed, and aged for 36 hours. The cells were then subjected to conventional formation for the first charge as follows: 0.02C constant current charging for 30 minutes, 0.05C constant current charging for 30 minutes, 0.1C constant current charging for 120 minutes, and 0.2C constant current charging for 240 minutes, with the cutoff voltage set at 3.85V. The cells were left standing for 1 hour. After 24 hours of standing at room temperature (12 hours each for both the forward and reverse directions), the cells were charged at 0.5C constant current to 4.2V and discharged at 0.2C constant current to 2.75V.

[0102] Examples 2 to 33

[0103] Examples 2 to 33 are used to illustrate the cylindrical lithium-ion batteries and their preparation methods disclosed in this application, and include most of the steps in Example 1, except that the battery composition shown in Table 1 is used. In Example 26, the lithium fluorosulfonyl imide is LiTFSI.

[0104] Comparative Examples 1 to 16

[0105] Comparative Examples 1 to 16 are used to illustrate the cylindrical lithium-ion batteries and their preparation methods disclosed in this application, and include most of the steps in Example 1, except that the battery composition shown in Table 1 is used. In Comparative Example 1, the non-aqueous electrolyte does not contain FEC.

[0106] Table 1

[0107] Performance Testing

[0108] The following performance tests were performed on the cylindrical lithium-ion batteries in the above embodiments and comparative examples, and the results are entered in Table 2.

[0109] 1) Rate discharge efficiency test: At 25°C, charge the formed battery to 4.2V using a 0.5C constant current and constant voltage charge, then discharge it to 2.75V using a 0.5C constant current and constant voltage charge, then charge it to 4.2V using a 0.5C constant current and constant voltage charge, and discharge it to 2.75V using a 4C constant current and constant voltage charge. Calculate the ratio of the 4C discharge capacity to the 0.5C discharge capacity. The calculation formula is as follows:

[0110] 4C / 0.5C rate discharge efficiency (%) = (4C discharge capacity / 0.5C discharge capacity) × 100%;

[0111] 2) Room temperature cycle performance test: At 25°C, charge the formed battery to 4.2V using a 1C constant current and constant voltage test, then discharge it to 2.75V using a 1C constant current test. After 1000 charge / discharge cycles, calculate the capacity retention rate at the 1000th cycle. The calculation formula is as follows:

[0112] 1000th cycle capacity retention rate (%) = (1000th cycle discharge capacity / first cycle discharge capacity) × 100%;

[0113] 3) Ultra-high temperature storage performance: Charge the formed battery to 4.2V at room temperature using a constant current and constant voltage of 1C, then discharge it to 2.75V at a constant current of 1C. Record the initial discharge capacity, then charge it to 4.2V at a constant current and constant voltage of 1C, then store it at 85°C for 12 hours. Finally, after the battery cools to room temperature, discharge it to 2.75V at 1C to measure the battery's retention capacity. The calculation formula is as follows:

[0114] Capacity retention rate (%) = retained capacity / initial capacity × 100%.

[0115] Table 2

[0116] It can be seen from the data in Table 2 that when the mass percentage D of DMC in the non-aqueous electrolyte, the ratio F of the molar content of lithium fluorosulfonyl imide to LiPF6 in the non-aqueous electrolyte, and the mass percentage S of silicon in the negative electrode material layer meet 0.05≤(100-D)*F / S≤8.75, and 50≤D≤75, 0.012≤F≤1, 5≤S≤20, the rate discharge efficiency, room temperature cycle performance, and ultra-high temperature storage performance of the cylindrical lithium ion battery can be effectively improved (Examples 1 to 33). In particular, when the cylindrical lithium ion battery meets 0.1≤(100-D)*F / S≤7.5, and 55≤D≤67, 0.06≤F≤0.85, 7≤S≤15, the various performances of the battery are better (for example, Examples 3, 5, 7, 13, and 14). When at least one of the values ​​of (100-D)*F / S, D, F or S is not within the preferred range, the relevant performance of the battery will be slightly deteriorated. For example, compared with Example 3, the D in the battery of Example 24 is higher than the preferred range, and the ultra-high temperature storage performance is reduced; the D in the battery of Example 25 is lower than the preferred range, and the rate discharge efficiency and normal temperature cycle performance are reduced. Compared with Example 3, the F in the battery of Example 20 is lower than the preferred range, and the normal temperature cycle performance is reduced; the F in the battery of Example 21 is higher than the preferred range, and the normal temperature cycle performance is reduced. Compared with Example 5, the S in the battery of Example 22 is higher than the preferred range, and the normal temperature cycle performance is reduced; the S in the battery of Example 23 is lower than the preferred range, and the normal temperature cycle performance and ultra-high temperature storage performance are reduced. When two or more of the values ​​of (100-D)*F / S, D, F, or S are outside the preferred range, the relevant performance of the battery deteriorates more significantly, such as the comparison of the battery performance in Examples 10 to 12; when the values ​​of (100-D)*F / S, D, F, or S are all outside the preferred range, the battery performance is relatively worse (for example, Example 10).

[0117] The lithium fluorosulfonyl imide in the non-aqueous electrolyte of the lithium-ion battery of this application can be selected from one or more of LiFSI (Examples 1-25, Examples 27-33) and LiTFSI (Example 26), all of which can meet the requirements. LiFSI is preferred, as it can achieve better battery performance (Example 3 vs. Example 26).

[0118] The silicon-based material in the negative electrode active material of the lithium-ion battery of the present application can be selected from one or more of silicon materials, silicon oxide materials, silicon-carbon composite materials, and silicon alloy materials, all of which can meet the requirements. In particular, when the silicon-based material is selected from a silicon-carbon composite material, the battery can achieve better performance (Example 7 vs. Examples 27-28, Example 5 vs. Examples 29-30).

[0119] The non-aqueous electrolyte of the lithium-ion battery of this application may further include conventional additives in the field to further enhance the overall performance of the battery. For example, compared with Example 5, the non-aqueous electrolyte of the battery of Example 31 further enhances the battery's rate discharge efficiency, room temperature cycling performance, and ultra-high temperature storage performance by adding 1% DTD. The non-aqueous electrolyte of the battery of Example 32 further enhances the battery's rate discharge efficiency and ultra-high temperature storage performance by adding 1% PS. The non-aqueous electrolyte of the battery of Example 33 further enhances the battery's ultra-high temperature storage performance by adding 1% tris-propargyl phosphate.

[0120] When the cylindrical lithium-ion battery does not meet 0.1≤(100-D)*F / S≤7.5, and 55≤D≤67, 0.06≤F≤0.85, and 7≤S≤15, the battery-related performance is significantly deteriorated:

[0121] Compared with Example 2, the DMC content D in the non-aqueous electrolyte of the battery of Comparative Example 1 is higher than the range of this application, and there is no FEC in the non-aqueous electrolyte, resulting in insufficient interface protection and severe deterioration of the battery's rate discharge efficiency, room temperature cycle performance, and ultra-high temperature storage performance.

[0122] Compared with Example 1, the DMC content D in the non-aqueous electrolyte of the battery of Comparative Example 3 is lower than the range of this application, the electrolyte wettability is poor, and the battery performance is significantly deteriorated.

[0123] Compared with Example 2, the ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte of the battery in Comparative Example 2 was lower than the range specified in this application, resulting in insufficient conductivity and correspondingly degraded battery performance. Compared with Example 1, the ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte of the battery in Comparative Example 4 was higher than the range specified in this application, resulting in severe interfacial corrosion and significant deterioration in battery performance.

[0124] Compared with Example 4, the mass percentage S of the silicon element in the negative electrode material layer of the battery of Comparative Example 5 is lower than the range of this application, and the mass percentage S of the silicon element in the negative electrode material layer of the battery of Comparative Example 6 is higher than the range of this application, both of which lead to mismatch of battery composition, material destruction, and obvious deterioration of battery performance.

[0125] Compared to Example 1, the DMC content D in the non-aqueous electrolyte of the battery in Comparative Example 7 is below the range of this application, and the ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 is also below the range of this application, resulting in significant degradation of battery performance. Compared to Comparative Example 3, the F value in the non-aqueous electrolyte of the battery in Comparative Example 7 is reduced to below the range of this application, further deteriorating battery performance. Compared to Comparative Example 7, the mass percentage S of silicon in the negative electrode material layer of the battery in Comparative Example 8 is reduced. Although battery performance improves slightly, it still deteriorates significantly compared to the range of this application.

[0126] All parameter indicators of the battery in Comparative Example 9 do not meet the requirements of this application. The battery performance is seriously deteriorated, and a diving phenomenon occurs. The ultra-high temperature storage performance cannot be tested.

[0127] In the battery of Comparative Example 10, the mass percentage S of the silicon element in the negative electrode material layer does not match the ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte; in the battery of Comparative Example 11, the mass percentage S of the silicon element in the negative electrode material layer does not match the DMC content D in the non-aqueous electrolyte, and the value of (100-D)*F / S is not within the scope of this application. The battery performance is severely deteriorated, and the ultra-high temperature storage performance cannot be tested.

[0128] Compared with Example 5, the DMC content D in the non-aqueous electrolyte of the battery in Comparative Example 12 is higher than the range of this application, and the ultra-high temperature storage performance cannot be tested.

[0129] In the batteries of Comparative Examples 13-16, although the mass percentage D of DMC in the non-aqueous electrolyte, the molar ratio F of lithium fluorosulfonyl imide to LiPF6 in the non-aqueous electrolyte, and the mass percentage S of silicon in the negative electrode material layer all met the requirements of this application, the value of (100-D)*F / S was outside the scope of this application, which also led to severe degradation of battery performance. This indicates that only when appropriate key components are selected in the battery and the relationship between the dosage and content of these key components meets the specific requirements of this application can the lithium-ion battery achieve the excellent performance described in this application.

[0130] In summary, the present application controls the mass percentage D of DMC in the non-aqueous electrolyte, the ratio F of the molar content of lithium fluorosulfonyl imide to LiPF6 in the non-aqueous electrolyte, and the mass percentage S of the silicon element in the negative electrode material layer to meet 0.05≤(100-D)*F / S≤8.75, and 50≤D≤75, 0.012≤F≤1, 5≤S≤20, thereby effectively suppressing the volume change of the silicon negative electrode, improving the problems of electrolyte consumption and active lithium loss, increased interface impedance, deterioration of cycle performance, and rapid attenuation of battery capacity in the late cycle, thereby improving the rate performance, room temperature cycle performance, and ultra-high temperature storage performance of the cylindrical lithium-ion battery, and improving the service life.

[0131] The technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A cylindrical lithium-ion battery, characterized in that: It comprises a positive electrode, a negative electrode and a non-aqueous electrolyte; the negative electrode comprises a negative electrode material layer containing a negative electrode active material, and the negative electrode active material comprises a silicon-based material; the non-aqueous electrolyte comprises a non-aqueous organic solvent and a lithium salt, the non-aqueous organic solvent comprises a chain carbonate containing DMC, and the lithium salt comprises LiPF6 and lithium fluorosulfonyl imide; The cylindrical lithium-ion battery meets the following conditions: 0.05≤(100-D)*F / S≤8.75, and 50≤D≤75, 0.012≤F≤1, 5≤S≤20; Wherein, D is the mass percentage of DMC in the non-aqueous electrolyte, in wt%; F is the ratio of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte; S is the mass percentage of silicon element in the negative electrode material layer, in wt%.

2. The cylindrical lithium-ion battery according to claim 1, characterized in that: The cylindrical lithium ion battery meets the following condition: 0.1≤(100-D)*F / S≤7.

5.

3. The cylindrical lithium ion battery according to claim 1 or 2, characterized in that: The mass percentage D of DMC in the non-aqueous electrolyte is 55wt% to 67wt%.

4. The cylindrical lithium ion battery according to claim 1 or 2, characterized in that: The ratio F of the molar content of lithium fluorosulfonyl imide to the molar content of LiPF6 in the non-aqueous electrolyte is 0.06 to 0.

85.

5. The cylindrical lithium ion battery according to claim 1 or 2, characterized in that: The mass percentage S of silicon element in the negative electrode material layer is 7wt% to 15wt%.

6. The cylindrical lithium-ion battery according to claim 1, characterized in that: The silicon-based material is selected from one or more of silicon materials, silicon oxide materials, silicon-carbon composite materials and silicon alloy materials.

7. The cylindrical lithium-ion battery according to claim 1, characterized in that: The lithium fluorosulfonyl imide is selected from one or more of LiFSI and LiTFSI.

8. The cylindrical lithium ion battery according to claim 1 or 7, characterized in that: The total molar content of the lithium salt is 0.9 mol / L to 3.5 mol / L, and 0.012≤F≤1.

9. The cylindrical lithium-ion battery according to claim 8, characterized in that: The total molar content of the lithium salt is 1.1 mol / L to 1.5 mol / L, and 0.06≤F≤0.

85.

10. The cylindrical lithium ion battery according to claim 1, characterized in that: The non-aqueous organic solvent further comprises one or more of cyclic carbonates, carboxylates and ethers.

11. The cylindrical lithium ion battery according to claim 10, characterized in that: The cyclic carbonate is selected from one or more of ethylene carbonate, fluoroethylene carbonate, vinylene carbonate, propylene carbonate and butylene carbonate.

12. The cylindrical lithium ion battery according to claim 10, characterized in that: The linear carbonate further comprises one or more of diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate.

13. The cylindrical lithium ion battery according to claim 10, characterized in that: The carboxylic acid ester is selected from one or more of methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate and ethyl trimethylacetate.

14. The cylindrical lithium ion battery according to claim 10, characterized in that: The ethers are selected from one or more of ethylene glycol dimethyl ether, 1,3-dioxolane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

15. The cylindrical lithium ion battery according to claim 1, characterized in that: The non-aqueous electrolyte further includes an additive, and the additive is selected from one or more of cyclic carbonate compounds, cyclic sulfate compounds, sultone compounds, phosphate compounds, borate compounds and nitrile compounds.

16. The cylindrical lithium ion battery according to claim 15, characterized in that: Based on the total mass of the non-aqueous electrolyte being 100%, the content of the additive is 0.01% to 10%.

17. The cylindrical lithium ion battery according to claim 15, characterized in that: The cyclic carbonate compound is selected from one or more of vinylene carbonate, ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethylethylene carbonate, bisfluoroethylene carbonate or the compound shown in the following structural formula 1: In the structural formula 1, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group.

18. The cylindrical lithium ion battery according to claim 15, characterized in that: The cyclic sulfate ester compound is selected from one or more of vinyl sulfate, 4-methylvinyl sulfate, and propylene sulfate.

19. The cylindrical lithium ion battery according to claim 15, characterized in that: The sultone compound is selected from one or more of 1,3-propane sultone, 1,4-butane sultone and propenyl-1,3-sultone.

20. The cylindrical lithium ion battery according to claim 15, characterized in that: The phosphate compound is selected from tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate and the compound shown in the following structural formula 2: In the structural formula 2, R 31 , R 32 , R 33 Each independently selected from a C1-C5 saturated hydrocarbon group, an unsaturated hydrocarbon group, a halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 , R 32 , R 33 At least one of them is an unsaturated hydrocarbon group.

21. The cylindrical lithium ion battery according to claim 15, characterized in that: The borate ester compound is selected from one or more of tris(trimethylsilyl)borate and tris(triethylsilyl)borate.

22. The cylindrical lithium ion battery according to claim 15, characterized in that: The nitrile compound is selected from one or more of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrinitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile and sebacononitrile.

Images