Battery and electronic device

Abstract

The invention relates to the technical field of batteries, in particular to a battery and an electronic device.The battery comprises a negative plate, a positive plate and electrolyte, a tab groove is formed in a positive active material layer, a positive tab is contained in the tab groove, and gummed paper is arranged on the surface of the positive tab; a groove is formed in the negative active material layer, the tab groove and the groove are oppositely arranged along the thickness direction of the positive plate, and an insulating glue layer is arranged in the groove; the sizes of the gummed paper along the width and length directions of the battery are respectively greater than those of the groove and the tab groove along the width and length directions of the battery; the electrolyte comprises an organic phosphorus compound containing cyano groups. According to the invention, the transmission efficiency difference between lithium ions around the tab protection adhesive paper and lithium ions at other positions can be shortened, the utilization rate of active substances around the tab adhesive is improved, and the long cycle performance, the fast charge performance and the lithium precipitation of the battery are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a battery and an electronic device comprising the same. BACKGROUND

[0002] With the rapid development of lithium ion battery technology, the demand for energy density of lithium ion batteries is further improved. However, due to the welding of the positive tab and the pasting of the positive tab protection paper, the tab slot of the positive electrode is protruded from the surface of the active material layer of the tab, and after the battery is assembled, the position of the tab is thicker than other areas of the battery, which will cause the consistency of the battery thickness to be poor, the overall thickness of the battery to increase, and thus the energy density of the battery to be lost.

[0003] Currently, in order to reduce the impact of the positive tab and the positive tab protection paper on the overall thickness of the battery during the battery design process, a recess is often provided on the surface of the negative electrode to improve the relative distance between the positive and negative electrodes around the tab due to the protrusion of the tab slot from the surface of the active material layer, shorten the lithium ion transmission distance, improve the transmission efficiency of lithium ions, and also improve the thickness consistency of the battery and the energy density of the battery.

[0004] However, since the length and width of the positive tab protection paper will exceed the size of the negative electrode surface recess, there will be a certain gap in the edge area of the positive tab protection paper compared to other active material layer areas, the lithium ion transmission distance in the edge area will be longer than that in other areas, causing the lithium ion transmission in this part to be slower than in other areas, which will easily form a concentration difference, exacerbate electrode polarization, and may lead to incomplete utilization of positive and negative active materials in the edge area, rapid decline in battery cycle performance, and lithium precipitation on the surface of the tab, further reducing the fast charging performance of the battery. SUMMARY

[0005] Based on the above problems, the present application provides a battery and an electronic device comprising the same. The battery of the present application can ensure that the lithium ion transmission efficiency difference between the edge of the tab protection paper and other positions is reduced, improve the utilization rate of active materials around the tab glue, and improve the long cycle performance, fast charging performance and lithium precipitation problem of the battery.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: The first aspect of the present application provides a battery comprising a negative tab, a positive tab and an electrolyte, the negative tab comprising a negative current collector and a negative active material layer on at least one side surface of the negative current collector, the positive tab comprising a positive current collector and a positive active material layer on at least one side surface of the positive current collector; The positive active material layer is provided with a tab slot, and a positive tab is accommodated in the tab slot, and the surface of the positive tab is provided with a paper. The negative active material layer is provided with a groove, the tab slot is arranged opposite to the groove along the thickness direction of the positive plate, and an insulating adhesive layer is arranged in the groove; The size of the adhesive paper along the width and length directions of the battery is greater than the size of the groove and the tab slot along the width and length directions of the battery, respectively; The electrolyte comprises a cyan group-containing organic phosphorus compound.

[0007] The second aspect of the present application provides an electronic device comprising the battery of the first aspect of the present application.

[0008] Compared with the prior art, the present application has at least the following advantages: The gap formed by the edge thickness of the positive and negative electrode tab protection adhesive paper will be filled with electrolyte. Therefore, the present application adds a cyan group-containing organic phosphorus compound to the electrolyte. This compound can form phosphorus-containing nanochannels on the electrode surface. Such channels have selective conduction effect on lithium ions, which can not only improve the interface conduction rate of lithium ions, but also block the co-intercalation of solvent molecules, thereby reducing the interface impedance. Especially in the gap of the edge of the tab protection adhesive paper where the electrolyte is enriched, because the content of the cyan group-containing organic phosphorus compound is higher, more lithium ion conduction channels can be formed, thereby further reducing the difference in lithium ion transport efficiency between the tab protection adhesive paper and other positions, improving the utilization rate of active material around the tab adhesive, and thus improving the long cycle performance, fast charging performance and lithium precipitation problem of the battery.

[0009] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited. The endpoints of the ranges and the values are approximations that are understood to encompass values approximating these. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 The cross-sectional structure schematic diagram of the positive plate and the negative plate provided by an embodiment of the present application.

[0011] Explanation of reference signs: Negative plate 100, positive plate 200, negative current collector 110, negative active material layer 120, positive current collector 210, positive active material layer 220, tab slot 221, positive tab 222, adhesive paper 223 DETAILED DESCRIPTION The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and explanatory in nature and are not intended to limit the application. In this document, data ranges include the endpoints unless otherwise indicated.

[0012] The first aspect of the present application provides a battery, such as Figure 1 As shown, it comprises a negative electrode sheet 100, a positive electrode sheet 200 and an electrolyte, the negative electrode sheet 100 comprises a negative electrode current collector 110 and a negative electrode active material layer 120 located on at least one side surface of the negative electrode current collector 110, the positive electrode sheet 200 comprises a positive electrode current collector 210 and a positive electrode active material layer 220 located on at least one side surface of the positive electrode current collector 210; the positive electrode active material layer 220 is provided with a tab slot 221, and a positive electrode tab 222 is accommodated in the tab slot 221, and the surface of the positive electrode tab 222 is provided with a glue paper 223. It can be understood that the tab slot is equivalent to providing a recess on the positive electrode active material layer for accommodating the positive electrode tab, so that the positive electrode tab is embedded inside the active material layer to avoid protrusion and ensure the flatness of the positive electrode sheet surface. In addition, the positive electrode active material layer can be located on both side surfaces of the positive electrode current collector, and the tab slot can also be provided on both side surfaces of the positive electrode current collector, as shown. Figure 1 The glue paper on the surface of the positive electrode tab, i.e. the tab protection glue paper, can prevent the positive electrode tab from directly contacting the negative electrode sheet to avoid short circuit, isolate the electrolyte from corroding the welding position of the positive electrode tab, and stabilize the positive electrode tab in the tab slot to avoid displacement during assembly.

[0013] In the present application, as shown, Figure 1 The negative electrode active material layer 120 is provided with a recess 121, the tab slot 221 and the recess 121 are oppositely arranged along the thickness direction of the positive electrode sheet 200, and the recess 121 is provided with an insulating glue layer 122. It can be understood that the positive electrode tab is embedded in the tab slot, and the glue paper and the positive electrode tab itself have a certain thickness, which will make the local area of the positive electrode sheet thicker than other areas; if the surface of the corresponding position of the negative electrode sheet is flat, the positive and negative electrodes will be pressed up after assembly, resulting in uneven thickness of the whole battery. Based on this, a receiving recess is needed to be arranged at the position of the negative electrode sheet opposite to the tab slot along the thickness direction, which is equivalent to providing a receiving space for the locally thickened area of the positive electrode sheet, thereby offsetting the local uneven thickness and ensuring the uniform thickness of the whole battery, and further improving the energy density of the battery. Further, the insulating glue layer in the recess can prevent the negative electrode current collector (copper foil) at the negative electrode recess from directly contacting the positive electrode tab to avoid short circuit, and can also fill the gap in the recess to prevent the negative electrode active material layer from falling off due to the setting of the recess, and can also buffer the pressure during assembly of the positive and negative electrode sheets.

[0014] Further, as shown, Figure 1As shown, the dimensions of the adhesive tape 223 along the width and length directions of the battery are larger than those of the groove 121 and the tab groove 221 along the width and length directions of the battery, respectively. This means that the dimension of the adhesive tape along the width direction of the battery is larger than that of the groove and the tab groove along the width direction of the battery, and the dimension of the adhesive tape along the length direction of the battery is larger than that of the groove and the tab groove along the length direction of the battery. In other words, the length and width of the adhesive tape are both larger than the dimensions of the groove and the tab groove in the same direction. The purpose of this design is to cover the burrs on the edges of the groove and the tab groove as much as possible, so as to avoid the burrs piercing the adhesive tape and causing the electrode to short circuit.

[0015] However, based on the above-mentioned adhesive tape design, there will be a certain gap in the edge area of ​​the positive electrode tab protective adhesive tape compared to other active material layers. The lithium ion transport distance in this edge area will still be farther than that in other areas, resulting in slower lithium ion transport in this part compared to other areas. This can easily lead to a concentration difference, exacerbate electrode polarization, and may result in incomplete utilization of the positive and negative electrode active materials in this edge area. The battery cycle performance will decline more rapidly, and lithium plating will occur on the electrode surface, causing a further decline in the battery's fast charging performance.

[0016] Based on this, the electrolyte of the present invention includes a cyano-containing organophosphorus compound. The gaps formed by the thickness of the protective paper edges of the positive and negative electrodes are filled by the electrolyte. The present invention, by adding a cyano-containing organophosphorus compound to the electrolyte, can utilize its properties to form phosphorus-containing nanochannels on the electrode surface. These channels have selective conduction for lithium ions, which can both increase the interfacial conduction rate of lithium ions and prevent the co-intercalation of solvent molecules, thereby reducing interfacial impedance. Especially in the gaps at the edges of the protective paper edges where the electrolyte is concentrated, the higher content of the cyano-containing organophosphorus compound allows for the formation of more lithium ion conduction channels, further narrowing the difference in lithium ion transport efficiency between the area around the protective paper and other locations, improving the utilization rate of the active material around the protective paper, and thus improving the battery's long-cycle performance, fast-charging performance, and lithium plating problem.

[0017] In summary, to address the impact of gaps between the edge area of ​​the positive electrode tab protective adhesive and other active material layers, this invention introduces a cyano-containing organophosphorus compound into the electrolyte. This can form phosphorus-containing nanochannels on the electrode surface, increasing the lithium-ion interface conduction rate, thereby narrowing the lithium-ion transport efficiency gap between the area around the adhesive and other locations, improving the utilization rate of active materials around the tab adhesive, and ultimately improving the battery's long-cycle performance, fast-charging performance, and lithium plating problem.

[0018] In one specific embodiment, the battery satisfies the following relationship: 1.5 ≤ a / b ≤ 100, for example, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90, or 100, where a is the thickness of the adhesive tape in μm; and b% is the mass percentage of the cyano-containing organophosphorus compound in the electrolyte. In a preferred embodiment, 2 ≤ a / b ≤ 60. In the calculation, both a and b are dimensionless values; for example, when a μm = 10 μm and b% = 1%, the result of a / b is 10.

[0019] Furthermore, by adjusting the relationship between the thickness 'a' of the tab protective paper and the mass content 'b' of the cyano-containing organophosphorus compound in the electrolyte, such that the relationship satisfies the formula: 1.5 ≤ a / b ≤ 100, an appropriate amount of cyano-containing organophosphorus compound can be provided according to the thickness of the tab protective paper, forming a stable phosphorus-containing lithium-ion channel. This further accelerates the transport of lithium ions at the interface in this region, improves the utilization rate of active materials, and enhances the interface transport efficiency. If a / b < 1.5 (e.g., a is too thin or b is too high), it will result in an excessive amount of cyano-containing organophosphorus compounds relative to a certain thickness of adhesive paper, which will increase the thickness of the interface protective layer and the viscosity of the electrolyte, thus hindering ion migration. If a / b > 100 (e.g., a is too thick or b is too low), the amount of cyano-containing organophosphorus compounds will be insufficient to form enough phosphorus-containing channels in the gaps at the edge of the adhesive paper, and the lithium-ion transport gap between this area and other locations will not be narrowed. The effect of further improving the low utilization rate of active materials, the aggravation of lithium plating problems, and the decline in fast charging performance will be limited. Therefore, by further controlling 2 ≤ a / b ≤ 60, the balance between channel demand and component content can be matched to achieve the goal of improving interface transport efficiency and improving battery performance.

[0020] In one specific embodiment, 0.05% ≤ b ≤ 5%, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, or 5%. In a preferred embodiment, 0.1% ≤ b ≤ 3%. When the content of cyano-containing organophosphorus compounds is too high, an excessively thick protective layer will form on the surface of the positive electrode, increasing the resistance to lithium-ion transport, increasing the internal resistance of the battery, and deteriorating the battery cycle performance.

[0021] In one specific embodiment, 5 μm ≤ a μm ≤ 30 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, and 30 μm. Within this range, the adhesive tape thickness can further improve the battery's long-cycle performance, fast-charging performance, and lithium plating problem. The adhesive tape should not be too thick, as excessive thickness will result in excessively large gaps between the positive and negative electrodes due to the thickness of the adhesive tape. The lithium-ion transport distance in the peripheral area of ​​this edge is longer than in other areas, causing slower lithium-ion transport in this part compared to other areas, thus affecting the improvement of battery performance. In a preferred embodiment, 8 μm ≤ a μm ≤ 25 μm.

[0022] Although a balance between the thickness 'a' of the electrode protective film and the mass percentage 'b' of the cyano-containing organophosphorus compound in the electrolyte has been established by controlling the relationship between the film thickness and the compound content, satisfying the formula 3 ≤ a / b ≤ 40, further limiting the ranges of 'a' and 'b' can further mitigate the problem of extreme values ​​of 'a' and 'b': limiting 'a' to 5 μm ≤ 30 μm directly avoids excessively thick 'a' leading to excessively large gaps between the positive and negative electrodes and increased lithium-ion transport distance, or excessively thin 'a' causing safety performance issues; while limiting 'b' to 0.05% ≤ 5% prevents excessively high 'b' from causing excessively thick positive electrode protective layer and increased electrolyte viscosity, or excessively low 'b' from causing insufficient modification effect. This more effectively improves interfacial transport efficiency and enhances the battery's long-cycle performance, fast-charging performance, and lithium plating problem.

[0023] In one specific embodiment, the chemical structural formula of the cyano-containing organophosphorus compound is shown in formula (Ⅰ): Equation (Ⅰ), R1, R2, and R3 are each independently selected from alkyl groups having 1-10 carbon atoms that are substituted or unsubstituted by a halogen, alkenyl groups having 1-10 carbon atoms that are substituted or unsubstituted by a halogen, and alkynyl groups having 1-10 carbon atoms that are substituted or unsubstituted by a halogen; the halogen includes at least one of F and Cl.

[0024] In one specific embodiment, the cyano-containing organophosphorus compound includes at least one of the following compounds:

[0025] In one specific embodiment, the electrolyte includes compound C, which includes at least one of 2,2-difluoroethyl acetate, ethyl 2,2-difluoroethyl acetate, ethyl butyrate, methyl butyrate, methyl propionate, and propyl acetate; the mass percentage of compound C in the electrolyte is c, where 10% ≤ c ≤ 60%, for example, 10%, 20%, 30%, 40%, 50%, or 60%. As shown in compound C, carboxylic acid ester solvents typically interact with lithium ions through electronegative atoms such as oxygen atoms. The oxygen atoms in the ester group form delocalized π bonds with the carbonyl group (C=O) through a conjugation effect, leading to a dispersion of negative charge. Therefore, the electrostatic attraction of oxygen atoms to lithium ions is weak. Furthermore, other components in the electrolyte (such as carbonate solvents and additives with highly electronegative functional groups) form solvation interactions with lithium ions, further weakening the binding between compound C and lithium ions due to their competitive relationship with lithium ions. This results in a significantly lower binding energy between compound C and lithium ions compared to other solvents. This invention utilizes this characteristic of compound C. By adding compound C to the electrolyte, it can promote rapid desolvation of lithium ions (the low binding energy of compound C directly lowers the energy threshold for desolvation, thus accelerating desolvation). Additionally, compound C has a low viscosity, greatly reducing the lithium ion migration barrier, further reducing the difference in lithium ion transport efficiency between the positive and negative electrodes and other locations around the electrode tab protective film, reducing polarization, and thus further improving battery cycle performance and lithium plating issues.

[0026] In one specific embodiment, the electrolyte includes compound D with the chemical structural formula as shown in formula (ⅠⅠ) and / or formula (ⅠⅠⅠ): Equation (ⅠⅠ), Equation (ⅠⅠⅠ), Wherein, R4, R5, R6, R7, R8, and R9 are respectively selected from alkyl groups with 1-10 carbon atoms that are halogenated or unsubstituted, alkenyl groups with 1-10 carbon atoms that are halogenated or unsubstituted, and alkynyl groups with 1-10 carbon atoms that are halogenated or unsubstituted; the halogen includes at least one of F and Cl.

[0027] In one specific embodiment, the mass content of compound D in the electrolyte is d, 0.1%≤d≤5%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0028] In one specific embodiment, the compound D comprises at least one of the following compounds:

[0029] The cyano functional group in compound D of this invention gives the nitrogen atom high electronegativity, enabling it to attract electrons and form a local negative charge center. Furthermore, the oxygen atom in the phosphorus oxide group (P=O) of compound D is connected to the phosphorus atom via a double bond, allowing the lone pair electrons of the oxygen atom to also be negatively charged. Thus, a negatively charged region composed of cyano and phosphorus oxide groups is formed in compound D, which readily reacts with lithium ions (Li₂O₃). + Electrostatic interactions occur, forming an organic-inorganic composite layer at the electrode interface. This composite layer combines the flexibility of organic components with the stability of inorganic components, effectively suppressing side reactions at the electrode / electrolyte interface and improving the battery's long-cycle performance and fast-charging performance.

[0030] Furthermore, during high-voltage charging, the cathode material is prone to the precipitation of active oxygen, forming oxygen vacancies, which causes instability in the cathode material and exacerbates battery side reactions. The phosphine groups of the cyano-containing organophosphorus compound in this invention can combine with oxygen vacancies on the cathode material surface to fill film defects. Compound D, on the other hand, can utilize the strong interaction formed between the phosphorus-oxygen bond (P=O) and the cathode material surface to transfer electrons with metal ions surrounding the oxygen vacancies, forming a "bridging" structure. This further stabilizes the lattice of the cathode material after defect repair by the cyano-containing organophosphorus compound, enhances the interfacial stability between the cathode material and the electrolyte, and suppresses side reactions. The cyano-containing organophosphorus compound repairs film defects, while compound D strengthens the cathode structure after defect repair through chemical bonds. The synergistic effect of these two compounds significantly improves the structural stability of the cathode material and reduces capacity decay. Moreover, compound D can form a more stable and dense CEI film on the surface of the cathode material, and provide more lithium-ion channels containing phosphorus compounds, especially in the electrolyte enrichment area near the tab protective paper, forming a higher quality CEI film, thereby improving the lithium-ion transport efficiency at the electrode interface, improving the utilization rate of electrode active materials, and further improving battery cycle performance and lithium plating problems.

[0031] In one specific embodiment, the electrolyte includes compound E, which comprises vinyl sulfate, methylene disulfonate, 1,3-propanesulfonate lactone, vinyl sulfite, propylene sulfite, 4-methylethylene sulfate, vinyl disulfite, trimethylsilylmethanesulfonate, dimethylmethylenesulfonate, 4-acetylphenyltrifluoromethanesulfonate, phenyltrifluoromethanesulfonate, 6-quinolinyltrifluoromethanesulfonate, 1-propylene-1,3-sulfonate lactone, 5-methyloxathiapentane 2,2-dioxide, 2,4-butanesulfonate lactone and 1,4-butanesulfonate lactone, mannitol carbonate sulfate, etc. , , At least one of them.

[0032] In one specific embodiment, the mass content of compound E in the electrolyte is e, 0.1%≤e≤5%, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0033] The cyano-containing organophosphorus compounds and compound D in this invention both contain a cyano (-C≡N) functional group. The cyano (-C≡N) group has high polarity (electronegativity 3.0) and strong coordination ability, readily reacting with Li. + The formation of a stable solvated sheath leads to Li + The desolvation energy barrier is elevated, especially at low temperatures (e.g., -20°C), significantly increasing the interfacial charge transfer resistance (Rct). Therefore, to further reduce the lithium-ion desolvation energy barrier, the electrolyte of this invention may also contain compound E, because the sulfur-oxygen double bond (S=O) in compound E can react with Li... + Coordination occurs; the oxygen atom in the sulfur-oxygen double bond has high electronegativity and a lone pair of electrons, which can act as a Lewis base to donate electron pairs. Li + As strong Lewis acids (empty orbitals), the two form a coordinate bond. Li can be formed + The complex formed with compound E weakens Li + Interactions with other molecules, thereby reducing Li + The solvation energy barrier is reduced, accelerating the desolvation process at the interface, reducing battery impedance, and improving battery cycle performance.

[0034] In one specific embodiment, the electrolyte includes compound F, which includes at least one of lithium difluorophosphate, lithium difluorooxalate borate, and lithium tetrafluoroborate. In one specific embodiment, the mass content of compound F in the electrolyte is f, where 0.1% ≤ f ≤ 3%, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5% or 3%.

[0035] Compound F can be further added to the electrolyte of the present invention. Since the reduction potential of compound F on the negative electrode surface is lower than that of conventional solvents, it can preferentially decompose to form a solid electrolyte interphase (SEI) film rich in inorganic (LiF, Li3PO4) and organic matter. LiF and Li3PO4 have high ionic conductivity, which can significantly reduce the charge transfer impedance on the negative electrode side, thereby further reducing the battery impedance and improving the high-rate cycle performance of the battery.

[0036] In one specific embodiment, the negative electrode active material layer contains a negative electrode active material, which contains a silicon-carbon composite material. The particle size of the silicon-carbon composite material satisfies the following relationship: (Dv90-Dv10) / Dv50≤1.5, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.3, 1.5; preferably, 0.1≤(Dv90-Dv10) / Dv50≤0.8.

[0037] In one specific embodiment, the particle size Dv50 of the silicon-carbon composite material is in the range of 5μm-15μm, for example, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm.

[0038] The negative electrode active material of this invention contains a silicon-carbon composite material, which can further improve the energy density of the battery. However, because the volume expansion of the silicon-carbon composite material is much greater than that of graphite, the SEI film of the silicon-carbon composite material will repeatedly rupture and form a new SEI film during cycling, resulting in a continuous increase in interfacial impedance. Furthermore, the diffusion coefficient of lithium-ion silicon-carbon composite material is much lower than that of graphite. Therefore, the electrochemical polarization of lithium ions in the negative electrode material will continuously increase, damaging the negative electrode material structure and degrading the battery cycle performance. This invention, by reducing the difference between Dv90 and Dv50, Dv10, and controlling (Dv90-Dv10) / Dv50≤1.5, can narrow the particle size range of the silicon-carbon composite material, reducing the problem of increased lithium-ion transport distance caused by excessively large particles; avoiding the problem of fewer reactive sites due to excessively small particles; and reducing the volume expansion difference between silicon-carbon composite material particles, greatly improving electrochemical polarization, thereby improving battery cycle performance.

[0039] In one specific embodiment, the OI value of the negative electrode active material layer is g, and the average sphericity of the silicon-carbon composite material is h. The g and h satisfy: 5≤g≤30, 0.8≤h<0.99, for example, g is 5, 6, 7, 10, 15, 20, 25, 30; for example, h is 0.8, 0.85, 0.88, 0.92, 0.95, 0.96, 0.97, 0.98, 0.99.

[0040] The negative electrode active material layer of this invention has a low OI value. The graphite layers in the negative electrode active material are aligned with the surface of the negative electrode sheet. Compared to negative electrode materials where the graphite layers are aligned parallel to the surface of the negative electrode sheet, this arrangement is more conducive to the migration of lithium ions within the negative electrode material, significantly improving the lithium ion insertion / extraction efficiency and enhancing the battery's fast-charging performance. Furthermore, due to the high average sphericity of the silicon-carbon composite material of this invention, it can further reduce the uneven expansion of the negative electrode active material, mitigating the increased impedance caused by continuous repair of the SEI film, which leads to increased electrochemical polarization and improves battery cycle performance and lithium plating issues. Negative electrode active materials generally contain both silicon-carbon composite materials and graphite materials. A low OI value primarily reflects the high migration efficiency of lithium ions in the graphite material; while a high sphericity indicates that the silicon-carbon composite material has a large specific surface area, providing more lithium ion migration channels. When both conditions are met simultaneously, the lithium ion insertion / extraction rate in the negative electrode active material can be optimized, thereby further improving the battery's fast-charging performance.

[0041] In one specific embodiment, the adhesive paper includes a substrate and an adhesive layer. The substrate is made of at least one of polyethylene phthalate, polyimide, polyvinyl chloride, and polypropylene. The adhesive layer contains at least one of styrene-butadiene rubber, acrylic resin, butyl rubber, polyethylene glycol, polymethyl methacrylate, polyisobutylene, styrene-isoprene-styrene block copolymer, polyvinylidene fluoride, and a copolymer of vinylidene fluoride and hexafluoropropylene.

[0042] In one specific embodiment, the adhesive layer contains at least one of polyisobutylene, styrene-isoprene-styrene block copolymer, polyvinylidene fluoride, and a copolymer of vinylidene fluoride-hexafluoropropylene.

[0043] In one specific embodiment, the adhesive layer further comprises inorganic particles, including at least one of alumina, boehmite, silicon dioxide, lithium aluminum titanium phosphate, and titanium dioxide.

[0044] In one specific embodiment, the substrate of the adhesive tape is a porous membrane substrate, which is formed by multiple fibers stacked in a cross pattern. The diameter of the fibers is 2μm to 10μm, the pore size of the porous membrane substrate is 0.1μm to 20μm, the thickness of the porous membrane substrate is 5μm to 20μm, and the thickness of the adhesive layer of the adhesive tape is 2μm to 15μm.

[0045] In one specific embodiment, the insulating adhesive layer also includes the substrate and the adhesive layer. The structure and composition of the substrate and adhesive layer of the insulating adhesive layer are the same as those of the adhesive paper described above, but in this specific embodiment, their compositions may be the same or different.

[0046] In one specific embodiment, the positive electrode active material layer includes a positive electrode active material, said positive electrode active material comprising a layered lithium composite oxide with the chemical formula Li. (1+x) Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; where M is one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0047] In one specific embodiment, the negative electrode active material further includes a carbon-based material, which includes at least one of artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, and soft carbon.

[0048] In one specific embodiment, the electrolyte includes a lithium salt, which includes one or two of lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorobis(oxalato)phosphate, lithium bis(oxalato)borate, lithium hexafluoroantimonyate, lithium hexafluoroarsenate, lithium bis(pentafluoroethylsulfonyl)imide, and lithium tri(trifluoromethylsulfonyl)methyl.

[0049] In one specific embodiment, the electrolyte includes an additive, which includes one or more of the following: vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, butadionitrile, glutaronitrile, adiponitrile, heptaonitrile, octadionitrile, sebaconitrile, 1,3,6-hexanetrionitrile, glycerol trionitrile, and 1,2-bis(2-cyanoethoxy)ethane.

[0050] The battery charging cutoff voltage of the present invention is greater than or equal to 4.5V.

[0051] A second aspect of the present invention provides an electronic device comprising the battery described in the first aspect of the present invention.

[0052] This invention does not limit the types of electronic devices, but may include, but is not limited to, laptops, input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0053] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0054] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0055] Example 1 1) Preparation of positive electrode sheet Lithium cobalt oxide (LiCoO2), polyvinylidene fluoride (PVDF), super P (SP), and carbon nanotubes (CNTs) were mixed in a mass ratio of 96:2:1.5:0.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until a homogeneous and fluid positive electrode active slurry was formed. The positive electrode active slurry was uniformly coated onto both surfaces of an aluminum foil to form a positive electrode active material layer. The coated aluminum foil was dried, then rolled and slit to obtain a positive electrode sheet. The tab welding positions on the positive electrode active layer of the positive electrode sheet were selected and cleaned by scraping to form tab grooves. Positive tabs were then welded into the tab grooves, and adhesive was applied to obtain the positive electrode sheet of this embodiment. The adhesive tape on the positive tabs was 12 μm thick.

[0056] 2) Preparation of negative electrode sheet Artificial graphite, silicon-carbon composite material (particle size Dv50=8.5μm, Dv10=6.7μm, Dv90=11.8μm, (Dv90-Dv10) / Dv50=0.6, sphericity=0.8), sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber, conductive carbon black (SP), and single-walled carbon nanotubes (SWCNTs) were mixed in a mass ratio of 70:24.5::2.5:1.5:1:0.5, and deionized water was added. The mixture was stirred in a vacuum mixer to obtain a negative electrode active slurry. The negative electrode active slurry was uniformly coated on both surfaces of a copper foil to form a negative electrode active material layer. The coated copper foil was dried at room temperature and then transferred to an 80°C oven for drying for 10 hours. After cold pressing, slitting, and scraping and cleaning at the position of the negative electrode active material layer corresponding to the positive electrode tab to form a groove, an insulating adhesive layer was applied to obtain the negative electrode sheet of this embodiment. Among them, the OI value of the negative electrode active material layer is g=15.

[0057] 3) Preparation of electrolyte In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), EC / PC were mixed uniformly at a mass ratio of 10:10. Then, 30% (by weight of the total electrolyte) of compound C (2,2-difluoroethyl acetate) was added, and after uniform mixing, 16% (by weight of the total electrolyte) of fully dried LiPF6 was quickly added and allowed to dissolve completely. Then, 1.5% (by weight of the total electrolyte) of a cyano-containing organophosphorus compound, 2.5% (by weight of the total electrolyte) of compound D (formula (II-1): formula (II-2) = 1.5:1), 0.5% (by weight of the total electrolyte) of compound E (ethylene sulfate), and 0.5% (by weight of the total electrolyte) of compound F (lithium difluorophosphate) were added. After thorough mixing, and after passing tests for moisture and free acid, the desired electrolyte was obtained.

[0058] 4) Preparation of lithium-ion batteries The positive electrode sheet from step 1), the negative electrode sheet from step 2), and the separator are stacked in the order of positive electrode sheet, separator, and negative electrode sheet, and then wound to obtain a battery cell. The battery cell is placed in an outer packaging aluminum foil, and the electrolyte from step 3) is injected into the outer packaging. After vacuum sealing, settling, formation, shaping, and sorting, a lithium-ion battery is obtained. The charge / discharge range of the battery of this invention is 3.0-4.55V.

[0059] Example 2 group This embodiment is based on Embodiment 1, except that the thickness a of the adhesive paper of the positive electrode and / or the mass content b of the cyano-containing organophosphorus compound in the electrolyte are changed, as detailed in Table 1.

[0060] Table 1 Example 3 Group This embodiment is based on Example 1, with the only difference being the change in the mass percentage c of compound C in the electrolyte and / or the specific selection of compound C. Specifically: Example 3-1: Compound C (2,2-difluoroethyl acetate) was added to the electrolyte at 9% of the total mass of the electrolyte. Example 3-2: Compound C (ethyl 2,2-difluoroacetate) was added to the electrolyte at 10% of the total mass of the electrolyte. Example 3-3: Compound C (ethyl butyrate) was added to the electrolyte at 60% of the total mass of the electrolyte. Examples 3-4: Compound C (2,2-difluoroethyl acetate) was added to the electrolyte at 61% of the total mass of the electrolyte. Examples 3-5 involve adding compound C (2,2-difluoroethyl acetate) to the electrolyte at 0% of the total mass of the electrolyte.

[0061] Example 4 group This embodiment is based on Example 1, with the only difference being the change in the mass percentage d of compound D in the electrolyte and / or the specific selection of compound D. Specifically: Example 4-1: Compound D (Formula (ⅠⅠⅠ-1): Formula (ⅠⅠⅠ-2) = 1.5:1) was added to the electrolyte at 0.1% of the total mass of the electrolyte. Example 4-2: Compound D (Formula (ⅠⅠ-5): Formula (ⅠⅠⅠ-5) = 1.5:1) was added to the electrolyte at 5% of the total mass of the electrolyte. In Examples 4-3, compound D (Formula (II-1): Formula (II-2) = 1.5:1) was added to the electrolyte at 5.2% of the total mass of the electrolyte. In Examples 4-4, compound D (Formula (II-1): Formula (II-2) = 1.5:1) was added to the electrolyte at 0% of the total mass of the electrolyte.

[0062] Example 5 group This embodiment is based on Example 1, with the only difference being the change in the mass percentage e of compound E in the electrolyte and / or the specific selection of compound E. Specifically: Example 5-1: Compound E (mannitol carbonate sulfate) in the electrolyte at 0.1% of the total mass of the electrolyte. Example 5-2, Compound E (1,3-propanesulfonate lactone) in the electrolyte at 5% of the total mass of the electrolyte. Examples 5-3: Compound E (ethylene sulfate) in the electrolyte at 5.2% of the total mass of the electrolyte. Examples 5-4: Compound E (ethylene sulfate) in the electrolyte at 0% of the total mass of the electrolyte.

[0063] Example 6 group This embodiment is based on Example 1, with the only difference being the change in the mass percentage f of compound F in the electrolyte and / or the specific selection of compound F. Specifically: Example 6-1, compound F (lithium difluorooxalate borate) was added to the electrolyte at 0.1% of the total mass of the electrolyte. Example 6-2, Compound F (lithium tetrafluoroborate) in the electrolyte at 3% of the total mass of the electrolyte. Examples 6-3: Compound F (lithium difluorophosphate) in the electrolyte at 3.2% of the total electrolyte mass. Examples 6-4: Compound F (lithium difluorophosphate) in the electrolyte at 0% of the total mass of the electrolyte.

[0064] Example 7 group This embodiment is based on Embodiment 1, with the only difference being that the particle size of the silicon-carbon material in the negative electrode active material layer and / or the average sphericity h of the silicon-carbon composite material are changed. Furthermore, the measured OI value of the negative electrode active material layer also changes according to the change in the particle size of the silicon-carbon material. Specifically: Example 7-1: The particle size of the silicon-carbon composite material is Dv90=19μm, Dv50=15μm, Dv10=14μm, (Dv90-Dv10) / Dv50=0.33, sphericity=0.9, and OI value g=22 for the negative electrode active material layer. Example 7-2: The particle size of the silicon-carbon composite material is Dv90=11.8μm, Dv50=8.5μm, Dv10=5μm, (Dv90-Dv10) / Dv50=0.8, sphericity=0.95, and OI value g=20 for the negative electrode active material layer. Example 7-3: The particle size of the silicon-carbon composite material is Dv90=11.8μm, Dv50=5.6μm, Dv10=3.4μm, (Dv90-Dv10) / Dv50=1.5, sphericity=0.8, and OI value g=11 for the negative electrode active material layer. In Examples 7-4, the particle size of the silicon-carbon composite material is Dv90=11.8μm, Dv50=5μm, Dv10=3.3μm, (Dv90-Dv10) / Dv50=1.7, sphericity=0.8, and OI value g=7 for the negative electrode active material layer.

[0065] Comparative Example 1 This comparative example is based on Example 1, except that no cyanide-containing organophosphorus compound is added to the electrolyte.

[0066] Comparative Example 2 This comparative example is based on Example 1, with the only difference being that no adhesive is applied to the tab groove during the preparation of the positive electrode sheet, and no adhesive is applied to the groove during the preparation of the negative electrode sheet.

[0067] Test case The lithium-ion batteries obtained in the examples and comparative examples were subjected to 25°C EIS test, 4C cycle test, and battery cycle lithium plating judgment test, respectively.

[0068] 1. 25℃ EIS test The batteries obtained in the examples and comparative examples were charged at 25°C to the upper limit voltage at 0.7C, with a cutoff current of 0.05C, left to stand for 10 minutes, and then discharged at 0.2C to 3V as the initial capacity, left to stand for 10 minutes. They were then charged at 0.5C to 50% of their initial capacity (SOC). After standing for 10 minutes, the battery EIS was tested using a CHI660E electrochemical workstation. Ten batteries were tested, and the average EIS value was recorded. The test results are shown in Table 2.

[0069] 2. 4C Cycle Test The batteries obtained in the examples and comparative examples were discharged to 3.0V at 0.5C at 25°C. They were then charged at a constant current of 4C to a voltage of 4.55V, followed by constant voltage charging at 4.55V to a current of 0.05C. After resting for 5 minutes, they were discharged at a constant current of 4C to a voltage of 3.0V, completing one charge-discharge cycle. The discharge capacity of week 1 was measured as x mAh, and the discharge capacity of week N was measured as y mAh. The capacity of week N was divided by the capacity of week 1 to obtain the cycle capacity retention rate R = y / x. The capacity retention rate of the battery after 500T cycles was recorded, and the test results are shown in Table 2.

[0070] 3. Battery cycle lithium plating assessment The batteries obtained in the examples and comparative examples were charged at 25°C with a constant current of 4C to a voltage of 4.55V, then charged at 4.55V with a constant voltage to a current of 0.05C, allowed to stand for 5 minutes, and then discharged at a constant current of 4C to a voltage of 3.0V. This constitutes one charge-discharge cycle. After 300T of cycles, the batteries were fully charged and disassembled to observe whether lithium plating was present on the surface of the electrolytic negative electrode. Lithium plating was categorized into four types: no lithium plating, slight lithium plating (lithium plating at the top and bottom edges of the electrode or slight lithium plating at the arc), lithium plating (lithium plating appears at the top and bottom edges of the electrode and at the arc, with slight lithium plating on the electrode surface, and the lithium plating area is less than 20%), and severe lithium plating (large-scale lithium plating across the entire electrode surface). The test results are recorded in Table 2.

[0071] Table 2 As shown in Table 2, in Comparative Example 1, the lack of cyano-containing organophosphorus compounds in the electrolyte resulted in decreased cycle performance and fast-charging performance, as well as severe lithium plating issues. In Comparative Example 2, the absence of adhesive tape or insulating layer in the tab grooves and recesses could lead to short circuits due to contact between the positive and negative electrodes, degrading battery safety. Furthermore, the lack of adhesive tape and insulating layer made it easy for powder to fall off the active layer edges, further affecting cycle performance and reducing volumetric energy density. In Examples 1-7, the addition of cyano-containing organophosphorus compounds to the electrolyte effectively reduced the lithium ion transport efficiency gap between the area around the tab protective tape and other locations, improved the utilization rate of active materials around the tab adhesive, and improved the battery's long-cycle performance, fast-charging performance, and lithium plating issues.

[0072] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A battery, characterized in that, The device includes a negative electrode, a positive electrode, and an electrolyte. The negative electrode includes a negative current collector and a negative active material layer located on at least one side of the surface of the negative current collector. The positive electrode includes a positive current collector and a positive active material layer located on at least one side of the surface of the positive current collector. A tab groove is provided on the positive electrode active material layer, a positive electrode tab is accommodated in the tab groove, and an adhesive paper is provided on the surface of the positive electrode tab; The negative electrode active material layer is provided with a groove, the tab groove and the groove are arranged opposite to each other along the thickness direction of the positive electrode sheet, and an insulating adhesive layer is provided in the groove; The dimensions of the adhesive tape along the width and length of the battery are respectively larger than the dimensions of the groove and the tab groove along the width and length of the battery; The electrolyte contains organophosphorus compounds containing cyano groups.

2. The battery according to claim 1, characterized in that, The battery satisfies the following relationship: 1.5≤a / b≤100, where a is the thickness of the adhesive paper in μm; b% is the mass percentage of the cyano-containing organophosphorus compound in the electrolyte; preferably 2≤a / b≤60. Preferably, 0.05% ≤ b% ≤ 5%; Preferably, 5 μm ≤ a μm ≤ 30 μm.

3. The battery according to claim 1, characterized in that, The chemical structural formula of the cyano-containing organophosphorus compound is shown in formula (Ⅰ): Equation (Ⅰ), Wherein, R1, R2, and R3 are each independently selected from alkyl groups having 1-10 carbon atoms that are substituted or unsubstituted by halogen, alkenyl groups having 1-10 carbon atoms that are substituted or unsubstituted by halogen, and alkynyl groups having 1-10 carbon atoms that are substituted or unsubstituted by halogen; the halogen includes at least one of F and Cl. Preferably, the cyano-containing organophosphorus compound comprises at least one of the following compounds: 。 4. The battery according to claim 1, characterized in that, The electrolyte includes compound C, which includes at least one of 2,2-difluoroethyl acetate, ethyl 2,2-difluoroethyl acetate, ethyl butyrate, methyl butyrate, methyl propionate, and propyl acetate. The mass percentage of compound C in the electrolyte is c, where 10% ≤ c ≤ 60%.

5. The battery according to claim 1, characterized in that, The electrolyte includes compound D with the chemical structural formulas shown in formula (ⅠⅠ) and / or (ⅠⅠⅠ): Equation (ⅠⅠ), Equation (ⅠⅠⅠ), Wherein, R4, R5, R6, R7, R8, and R9 are respectively selected from alkyl groups with 1-10 carbon atoms that are halogenated or unsubstituted, alkenyl groups with 1-10 carbon atoms that are halogenated or unsubstituted, and alkynyl groups with 1-10 carbon atoms that are halogenated or unsubstituted; the halogen includes at least one of F and Cl.

6. The battery according to claim 5, characterized in that, The mass percentage of compound D in the electrolyte is d, where 0.1% ≤ d ≤ 5%; And / or, the compound D comprises at least one of the following compounds: 。 7. The battery according to claim 1, characterized in that, The electrolyte contains compound E, which includes vinyl sulfate, methylene methane disulfonate, 1,3-propanesulfonate lactone, vinyl sulfite, propylene sulfite, 4-methylethylene sulfate, vinyl disulfite, trimethylsilylmethanesulfonate, dimethylmethylenesulfonate, 4-acetylphenyltrifluoromethanesulfonate, phenyltrifluoromethanesulfonate, 6-quinolinyltrifluoromethanesulfonate, 1-propylene-1,3-sulfonate lactone, 5-methyloxathiapentane 2,2-dioxide, 2,4-butanesulfonate lactone, 1,4-butanesulfonate lactone, and mannitol carbonate sulfate. , , At least one of them; The mass percentage of compound E in the electrolyte is e, where 0.1% ≤ e ≤ 5%.

8. The battery according to claim 1, characterized in that, The electrolyte contains compound F, which includes at least one of lithium difluorophosphate, lithium difluorooxalate borate, and lithium tetrafluoroborate. The mass percentage of compound F in the electrolyte is f, where 0.1% ≤ f ≤ 3%.

9. The battery according to claim 1, characterized in that, The negative electrode active material layer contains a negative electrode active material, which contains a silicon-carbon composite material. The particle size of the silicon-carbon composite material satisfies the following relationship: (Dv90-Dv10) / Dv50≤1.5; preferably, 0.1≤(Dv90-Dv10) / Dv50≤0.

8. The OI value of the negative electrode active material layer is g, and the average sphericity of the silicon-carbon composite material is h. The g and h satisfy: 5≤g≤30, 0.8≤h<0.

99.

10. An electronic device, characterized in that, The electronic device includes the battery as described in any one of claims 1-9.

Images