Battery, electrochemical device and electrical device

Abstract

Battery comprising a battery cell, the battery cell comprising a negative electrode plate and an electrode tab arranged on the negative electrode plate; wherein a negative active material layer of the negative electrode plate contains silicon, the mass percent of silicon in the negative active material layer being “b” in units of “%”; wherein a maximum distance between the electrode tab and an end of the negative electrode plate being “d” in units of “mm” in a direction parallel to a long edge of the negative electrode plate; wherein a projection direction of the electrode tab being a first direction, a distance of a connection between the electrode tab and the negative electrode plate in a direction perpendicular to the first direction being equal to a width “m” of the electrode tab being equal to units of “mm”, and wherein “b”, “d”, and “m” satisfy the following relationship: − 3.1 ≤ L gmd × b ≤ − 0.11.

Description

TECHNICAL AREA

[0001] The present application relates to the field of batteries, in particular to a battery, an electrochemical device and an electrical device. BACKGROUND

[0002] A battery cell contains electrode tabs. Based on their position, the electrode tabs can be classified as upward-protruding or laterally protruding. The term "laterally protruding electrode tab" refers to an electrode tab that extends from a short edge of an electrode plate along the direction of extension of a long edge of the electrode plate, while the term "upward-protruding electrode tab" refers to an electrode tab that extends from the long edge of the electrode plate along the direction of extension of the short edge of the electrode plate. Conventional battery cells typically have electrode tabs located at or near the short edge and are manufactured using stacking or winding processes.

[0003] The electrode plate serves to transfer current from the battery cell to external circuits. Currently, battery electrode plates are manufactured with increasing lengths to increase battery energy density, resulting in an uneven current density distribution along the plate's length. In particular, section a of the electrode plate far from the electrode plate exhibits a lower current density, leading to increased electrode plate impedance, which is detrimental to improving the battery's fast-charging performance. SUMMARY OF THE INVENTION

[0004] Therefore, the technical problem to be solved by the present application consists in overcoming the disadvantage of poor fast-charging performance exhibited by prior art batteries, thereby providing a battery, an electrochemical device and an electrical device which solve the aforementioned problems.

[0005] To solve the above problem, the present application provides a battery comprising a battery cell, wherein the battery cell comprises a negative electrode plate and an electrode tab arranged on the negative electrode plate; wherein a negative active material layer of the negative electrode plate contains silicon, the mass percent of silicon in the negative active material layer “b” is in the unit “%”; in a direction parallel to a direction of the long edge of the negative electrode plate, a maximum distance between the electrode tab and an end of the negative electrode plate is “d” in the unit “mm”; a projection direction of the electrode tab is a first direction, wherein a distance of a connection between the electrode tab and the negative electrode plate in a direction perpendicular to the first direction corresponds to a width “m” of the electrode tab in the unit “mm”.refers to this and b, “d” and “m” satisfy the following relationship: −3,1≤Lgmd×b≤−0,11.

[0006] The present application provides an electrochemical device comprising the above-mentioned battery.

[0007] The present application provides an electrical device comprising the above electrochemical device.

[0008] The beneficial effects of the present application are as follows: The battery disclosed in the present application comprises a battery cell, wherein the mass percent value “b” of silicon in the negative active material layer, the maximum distance “d” between the electrode tab and the ends of the negative electrode plate in the direction of the long edge, and the width “m” of the electrode tab are controlled such that b, “d”, and “m” express the relationship −3.1≤Lgmd×b≤−0.11 fulfill; wherein, in the present application, the current carrying capacity of the electrode plate can be effectively improved by controlling these parameters, ensuring the energy density of the battery, thereby improving the fast charging performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To better illustrate the technical solutions in the specific embodiments of the present application or the prior art, a brief introduction to the drawings necessary for describing specific embodiments or the prior art is given below. It is understood that the drawings described below represent some embodiments of the present application, and that a person skilled in the art can create other drawings based on these drawings without inventive effort. Fig.1 is a schematic structural diagram of an upwardly protruding electrode tab in an embodiment of the present application; Fig. Figure 2 is a schematic structural diagram of a laterally protruding electrode tab in an embodiment of the present application. DETAILED DESCRIPTION

[0010] The following embodiments are listed for a better understanding of the present application and are neither limited to the best embodiments described nor do they restrict the content and scope of protection of the present application. Any product identical to or similar to the present application, obtained by anyone through inspiration of the present application or by combining features of the present application with features of the prior art, falls within the scope of protection of the present application.

[0011] For experimental steps or conditions not specifically described in the embodiments, procedures or conditions may be carried out or set according to conventional experimental procedures described in the literature in this field. Reagents or instruments without manufacturer information are conventional reagent products that can be purchased on the market.

[0012] The “range” disclosed in the present application is defined in terms of lower and upper limits, whereby a given range is defined by selecting a lower limit and an upper limit that define the boundaries of a specific range. The range defined in this way may or may not include the endpoint values ​​and may be combined arbitrarily, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 50% to 90% and 60% to 80% are listed for a specific parameter, it is agreed that ranges of 50% to 80% and 60% to 90% are also provided for. Furthermore, if minimum values ​​of ranges 1 and 2 are listed, and if maximum values ​​of ranges 3, 4, and 5 are listed, all of the following ranges are provided for: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.Unless otherwise stated, the number range “a to b” in this application illustrates an abbreviated expression of any combination of real numbers between a and b, where a and “b” are real numbers. For example, the number range “0.5 to 4” means that all real numbers between “0.5 to 4” have been listed here, such as: 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, etc., where “0.5 to 4” is only an abbreviated expression of these number combinations.

[0013] The present application discloses a battery comprising a battery cell. The battery cell comprises a negative electrode plate and an electrode tab arranged on the negative electrode plate. A negative active material layer of the negative electrode plate contains silicon, and the mass percentage of silicon in the negative active material layer is "b" in the unit "%". In a direction parallel to a long edge of the negative electrode plate, a maximum distance between the electrode tab and an end of the electrode plate is "d" in the unit "mm". A projection direction of the electrode tab is a first direction, wherein a distance of a connection between the electrode tab and the electrode plate in a direction perpendicular to the first direction corresponds to a width "m" of the electrode tab in the unit "mm". b, "d", and "m" satisfy the following relationship: −3,1≤Lgmd×b≤−0,11. In the present application, the value of Lgmd×b Accept any value between -3.1 and -0.11, for example: -3.1, -3.0, -2.5, -2, -1.5, -1, -0.5, -0.13, -0.11 etc.

[0014] In the present application, ‘b’ refers to the mass percentage of silicon in the negative active material layer. Adding silicon to the negative active material layer increases the overall energy density of the battery. However, adding silicon also affects the impedance of the electrode plate, with a higher silicon content resulting in increased electrode plate impedance, thus impacting fast-charging performance. ‘d’ refers to the distance between the electrode tab and the end of the electrode plate. The electrode tab facilitates current flow, and the distance between the electrode tab and the end of the electrode plate affects the current path length.At positions further away from the electrode tab, the impedance for current flow increases, resulting in a lower current density at the end of the electrode plate far from the electrode tab, thus affecting the battery's fast-charging performance. Furthermore, "m" refers to the width of the connection between the electrode tab and the electrode plate body. The width of this connection affects the current magnitude; that is, the wider the connection, the greater the current carrying capacity and the lower the resistance and energy loss, resulting in a higher current.

[0015] The present application addresses the problem of increased electrode plate impedance caused by a long electron transport path by comprehensively controlling the relationship between the silicon content "b", the distance "d" between the electrode tab and the end of the negative electrode plate, and the width of the connection "m" between the electrode tab and the electrode plate body. Specifically, if the value of "b" is too low, the energy density is low; if the value of "b" is too high, the electrode plate impedance is relatively high; and if the value of "m" is too small, the current-carrying capacity is poor.Therefore, if the value of m / (d×b) is too small, a long electron transport path and high impedance at the end of the electrode plate result, leading to a high DCR and ultimately poor fast-charging performance; if the value of m / (d×b) is too large, the battery's DCR is low and the fast-charging performance is good, but the battery's energy density is low. Studies have shown that the relationship between the value of m / (d×b) and fast-charging performance and energy density is non-linear, making it possible to filter batteries with both good fast-charging performance and good energy density based on the value of m / (d×b). In the present application, the value of m / (d×b) is processed using a logarithmic function, and the processed values ​​enable reasonable data analysis and application.Batteries with both good fast-charging performance and good energy density can be effectively achieved using the processed values. This means that the goal of improving the battery's fast-charging performance while meeting the energy density requirement can be achieved by adjusting the value of... Lgmd×b so that it is controlled so that it lies between -3.1 and -0.11.

[0016] Furthermore, the overall performance of the energy density and the fast-charging performance of the battery in the present application are better, with the value of Lgmd×b so that it is controlled within a more preferred range of -1.8 to -0.7.

[0017] In a preferred embodiment of the present application, the percentage content “b” of silicon in the negative active material layer is optimized in the unit “%”. In particular, the value of “b” must not be too small, because a value that is too small affects the energy density of the battery; the value of “b” must also not be too high, because a value that is too high indicates an excessive silicon content, which can easily cause the electrode plate to have a higher impedance, thereby affecting the fast-charging performance of the electrode plate. The reasons why an excess silicon content causes a higher impedance of the electrode plate are as follows: 1) Silicon itself has poor conductivity; compared to carbon materials, pure silicon has a much lower conductivity.1) As the silicon content increases, the overall conductivity of the composite material decreases, resulting in increased internal resistance and affecting fast-charging performance; 2) Silicon undergoes a large volume change, meaning it experiences significant volume expansion and contraction of up to 300% during charging and discharging. Such a large volume change can cause poor contact between material particles or even tearing, forming "ineffective silicon" that obstructs the electron transport path and increases the resistance of the electrochemical reaction, thereby increasing the battery's internal resistance; 3) During the first fast-charging cycle, a solid electrolyte interface (SEI) film forms on the silicon surface.Due to the large volume change of silicon, the SEI film is continuously broken and reformed during charging and discharging, which not only consumes lithium ions in the electrolyte but also increases the interfacial impedance, further increasing the internal resistance of the battery; 4) With increasing silicon content, the structural stability of the composite material deteriorates, making it susceptible to pulverization and delamination, reducing the effective contact area, and increasing the contact resistance of the battery. Therefore, in the present application, the range of the value of 'b' is 1.25 to 16, preferably 2.5 to 7.5. For example, b% is controlled to be 1.25%, 1.5%, 2%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc.

[0018] In a preferred embodiment of the present application, the maximum distance “d” between the electrode tab and the ends of the negative electrode plate is optimized in the extension direction of the long edge of the negative electrode. If the electrode tab extends from the extension direction of the long edge of the negative electrode plate, the maximum distance from the electrode tab to the end of the electrode plate is also the length of the electrode plate.If the electrode tab projects in a direction perpendicular to the extension direction of the long edge of the electrode plate, the maximum distance from the electrode tab to the end of the electrode plate is the distance between the electrode tab and the end of the electrode plate furthest from the electrode tab. In the present application, the value of "d" must not be too high because an excessively high value of "d" results in an excessively long electron transport path, causing an uneven current density distribution, high electrode plate impedance, and affecting the fast-charging performance; therefore, for electrode plates of the same length, an electrode plate with a smaller value of "d" is preferable.However, in the case of electrode plates of different lengths, the value of "d" must not be too small, because a value of "d" that is too small usually requires a shortening of the length of the electrode plate, which affects the energy density of the battery; therefore, the value of "d" in the present application is preferably 42 to 1000 and preferably 250 to 450, all in the unit "mm"; for example: the value of "d" is controlled such that it is 42, 45, 50, 60, 80, 100, 150, 200, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 960, 1000 etc.;

[0019] In a preferred embodiment, the projection direction of the electrode tab refers to a first direction, and the distance of the connection between the electrode tab and the negative electrode plate in a direction perpendicular to the first direction refers to the width "m" of the electrode tab. In the present application, the width "m" of the connection between the electrode tab and the negative electrode plate is optimized; the value of "m" must not be too small, because a value of "m" that is too small results in a small current-carrying cross-section, a low current-carrying capacity, poor current-conducting capability of the electrode plate, and an increased internal resistance of the electrode plate.Furthermore, the value of "m" must not be too high, because an excessively high value of "m" leads to problems such as increased impedance, lower energy density, and increased packing difficulty because: space in the battery is limited; excessively large electrode tabs can prevent the elements in the battery from being properly fitted to the available space, thus affecting battery integration and increasing the difficulty of packing the battery; moreover, enlarged electrode tabs result in an increase in the overall weight of the battery, thereby reducing the energy density (Wh / kg). Therefore, the value of "m" in the present application is between 9 and 960, preferably between 50 and 180. For example: the value of "m" is controlled so that it is 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 80, 100, 150, 200, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 960 etc.

[0020] In the present application, the areal density of the negative active material layer is further optimized. The areal density influences the fast-charging performance of the battery; that is, a lower areal density results in a thinner electrode plate, lower battery impedance, and a shorter lithium-ion transport path, which is advantageous for improving fast-charging performance.However, the areal density must not be too low, because a low areal density means less coated active material and a lower energy density of the battery; the areal density must also not be too high, because a high areal density means a longer transport path for the lithium ions and a higher internal resistance of the battery, which can easily cause a bottleneck in the lithium ion migration path and prevents the lithium ions from becoming fully trapped and reversing this trapping within a short period, thereby increasing polarization and consequently resulting in low charging efficiency during conventional or fast charging, which is therefore not conducive to improving fast-charging capability. The preferred areal density in the present application is 90–300 g / m². 2 ; for example: the areal density is controlled so that it is 90 g / m² 2, 100 g / m 2 , 150 g / m 2 , 200 g / m 2 , 250 g / m 2 , 300 g / m 2 etc. amounts.

[0021] In the present application, the density of the negative active material layer is further optimized. If the density is too high, the distance between particles decreases, and the particles come into closer contact, thereby increasing the electron conductivity but reducing or blocking channels for ion movement. This is not conducive to the rapid movement of a large number of ions. Consequently, the migration rate of the lithium ion cannot keep pace with the charging rate, leading to high polarization within the battery. The upper voltage limit of the battery is easily reached during fast charging, causing it to switch to a lower charging rate. This results in lower charging rates required to achieve the necessary state of charge (SOC) and a deterioration of fast-charging capability with longer charging times.If the density is too low, the distance between particles increases, the number of ion channels increases, and electrolyte absorption increases, which is advantageous for rapid ion movement. However, excessive distance between particles leads to a longer migration path for lithium ions within the electrode. This increases the diffusion time and the difficulty of lithium ion diffusion within the electrode. During fast charging, lithium ions must migrate rapidly from the electrolyte, thereby incorporating them into the electrode material. If the lithium ion migration path is too long, slower charging and a reduction in fast-charging efficiency result. Therefore, the density in the present application is comprehensively controlled to be between 1.2 and 2.3 g / m². 3 is the amount. If the degree of compaction is relatively low, for example 1.2 to 1.6 g / m³ 3 , can the value of the formula Lgmd×b, which is controlled so that it lies in the range of 1.8 to -0.7, results in the battery having superior fast-charging performance; if the compression ratio is relatively high, for example 1.6 to 2.3 g / m³ 3 The "m" value in the formula is controlled to lie within the range of 50 to 960, enabling the battery to exhibit superior fast-charging performance. The compression ratio mentioned above can be 1.2 g / m³. 3 , 1.4 g / m³ 3 , 1.5 g / m² 3 , 1.6 g / m² 3 , 1.7 g / m³ 3 , 1.8 g / m² 3 , 1.9 g / m² 3 , 2.0 g / m² 3 , 2.3 g / m³ 3 etc.

[0022] In a preferred configuration, the electrode tab is a laterally projecting electrode tab, meaning that the electrode tab protrudes in the direction of extension of the long edge of the negative electrode plate. In a direction perpendicular to the projection direction of the electrode tab, the ratio between the width of the electrode tab and the width of the negative electrode plate is greater than or equal to 0.5 and less than or equal to 1, which allows for a better increase in current carrying capacity, thereby reducing internal resistance and improving the fast-charging performance of the battery cell.

[0023] As a preferred configuration to ensure a relatively high energy density, the negative electrode plate has a long rim length of ≥300 mm; wherein the long rim length of the negative electrode plate can be 300 - 1100 mm; in particular, the long rim length of the negative electrode plate can be 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm.

[0024] And / or the battery cell is a stacked battery cell, which refers to a battery cell that is formed by stacking a positive electrode plate, a negative electrode plate and a separator using a stacking process.

[0025] The following adequate descriptions are of embodiments of an electrochemical device and an electrical device of the present application. However, unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of well-known substances and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is made available to those skilled in the art to enable a comprehensive understanding of this application and is not intended to limit the subject matter specified in the claims. [Electrochemical device]

[0026] The electrochemical device in the present application relates to a secondary battery, also known as a rechargeable battery or accumulator, which refers to a battery that can be reused by activating active materials by charging after discharging.

[0027] In general, a secondary battery comprises a battery cell, an electrolyte, and an outer casing. The battery cell includes electrode plates, consisting of a positive and a negative electrode plate, electrode tabs on the electrode plates, and a separator between the positive and negative electrode plates. The electrode tabs are usually integrally formed with the current collector on the electrode plates. The battery cell and the electrolyte are contained within the outer casing. During the charging and discharging of the battery, active ions (such as lithium ions) move back and forth between the positive and negative electrode plates, undergoing confinement and reversal of confinement.The separator is positioned between the positive and negative electrode plates primarily to prevent a short circuit between them, while also allowing the passage of active ions. The electrolyte, located between the positive and negative electrode plates, primarily serves to conduct the active ions.

[0028] For example, the process for manufacturing the secondary battery is as follows. The positive and negative electrode plates are manufactured separately. The electrode tabs are formed during the electrode plate forming process. Specifically, in the electrode plate forming process, a slurry is first applied to the current collector, creating a coated area and an uncoated area on the current collector. After drying and calendering, the resulting structure is cut to form electrode tabs by trimming away the uncoated area. The material for the electrode tabs is the same as that of the current collector in the electrode plate. For example, if the current collector of the negative electrode plate is made of copper, the electrode tab on the negative electrode plate is also made of copper.The electrode plates with electrode tabs and separator are stacked in this order, with the separator positioned between the positive and negative electrode plates to keep them apart. The resulting structure is then coiled and placed in the outer casing. After drying, electrolyte is injected. Following processes such as vacuum packaging, settling, formation, and shaping, the secondary battery is obtained. [Positive electrode plate]

[0029] A positive electrode plate typically comprises a positive current collector and a positive film layer arranged on at least one side of the positive current collector. The positive film layer comprises a positive active material, which can be any existing positive active material or an optimized positive active material based on existing ones.

[0030] In the present application, the type of positive active material is not subject to any specific restriction. For example, the positive active material in the present application includes lithium-containing transition metal oxides (e.g., LiCoO2), phosphides (e.g., LiFePO4), or lithium inclusion compounds (e.g., positive materials of a binary lithium battery, such as lithium cobalt oxide, lithium nickel oxide, or positive materials of a ternary lithium battery, such as nickel cobalt manganese lithium oxide, nickel cobalt aluminum lithium oxide), etc. As one configuration, the positive active material in the present application is preferably LiNi. x Co y Mn z O2, where 1 > x ≥ 0.5, x + y + z = 1.

[0031] In some embodiments, the positive electrode plate can be produced by the following method. The above components for producing the positive electrode plate, such as a positive active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone), forming a positive slurry; the positive slurry is applied to the positive current collector, and after drying, calendering, cutting, and other processes, the positive electrode plate can be obtained.

[0032] In the present application, the binder is used to improve adhesion between the particles in the positive active material and between the positive active material and the current collector. The present application does not impose any specific restrictions regarding the type of binder for the positive electrode plate, and the binder may be one of the conventional options used in batteries. In particular, the binder may be polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethylcellulose (CMC), and / or sodium alginate.

[0033] In the present application, the positive current collector is not subject to any specific restriction as long as it has conductivity and does not cause adverse chemical changes in the battery, and it may be made of materials such as stainless steel, aluminum, nickel, titanium, burnt carbon, or aluminum or stainless steel that has undergone a surface treatment with a carbon, nickel, titanium, silver, etc. [Negative electrode plate]

[0034] The negative electrode plate includes a negative current collector and a negative active material layer arranged on at least one side of the negative current collector. The negative active material layer contains silicon; that is, the negative active material enclosed in the negative active material layer includes at least one silicon-based material. In the present application, the type of silicon-based material is not subject to any specific restriction. By way of example, the silicon-based material may be a silicon-oxygen material and / or a silicon-carbon material. In some embodiments, the negative active material in the negative active material layer may optionally include synthetic graphite, natural graphite, and / or hard carbon.

[0035] In some embodiments, the negative electrode plate can be manufactured by the following method. The above components for manufacturing the negative electrode plate, such as the negative active material, the conductive agent, the binder, and any other components, are dispersed in a solvent (e.g., water), forming a negative slurry. The negative slurry is applied to the negative current collector, and after drying, calendering, cutting, and other processes, the negative electrode plate with an electrode tab can be obtained.

[0036] In the present application, the type of negative conductive material is not subject to any specific restriction. In some embodiments, the negative conductive material may, for example, be one or more conventional negative conductive materials, such as carbon black, carbon nanotubes, etc.

[0037] In the present application, the type of negative binder is not subject to any specific restrictions. In some embodiments, the binder may, for example, be one or more conventional negative binders, such as styrene-butadiene rubber latex (SBR), polyvinylidene fluoride (PVDF), etc.

[0038] In the present application, the type of negative current collector is not subject to any specific restriction. In some embodiments, the negative current collector may, for example, be one of the conventional negative current collectors, such as copper foil. [Electrolyte]

[0039] The electrolyte serves to conduct ions between the positive and negative electrode plates. In the present application, the type of electrolyte, which can be selected according to the requirements, is not subject to any specific restriction. For example, the electrolyte in the present application can be various electrolytes suitable for electrochemical energy storage devices in this field. The electrolyte includes an electrolyte salt and a solvent, and the electrolyte salt typically includes a lithium salt; additives can also be added to the electrolyte.

[0040] Specifically, the lithium salt includes lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and / or lithium tetrafluoro(oxalato)phosphate (LiTFOP). The electrolyte concentration in the electrolyte solution can range from 0.5 to 5 mol / L.

[0041] In particular, the solvent includes ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butanediol (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and / or diethyl sulfone (ESE).

[0042] In some embodiments, the additive may be, for example, conventional electrolyte additives such as fluoroethylene carbonate (FEC), chloroethyl carbonate (CEC), vinylene carbonate (VC). [Separator]

[0043] In some embodiments, the secondary battery also includes a separator. In the present application, the type of separator is not subject to any specific restriction, and any known separator with a porous structure, good chemical resistance, and mechanical stability can be used.

[0044] In some embodiments, the separator may be made of, for example, PP, PE, and / or PP / PE, and the surface of the separator may be provided with an inorganic and / or organic coating. The inorganic coating may be selected from a ceramic aluminum oxide layer, vermiculite, etc.; the organic layer may be selected from PVDF, etc. Designs

[0045] An electrochemical device, for example: a secondary battery, includes a positive electrode plate, a negative electrode plate with an electrode tab, a separator, an electrolyte and an outer casing. 1. Production of a positive electrode plate

[0046] The specific procedure for manufacturing the positive electrode plate is as follows: a positive active material (i.e., LiNi) 0,9 Co 0,05 Mn 0,05O2) is obtained, the positive active material, a conductive agent (i.e., acetylene carbon black), a binder (i.e., PVDF) are mixed in a mass ratio of 92:4:4, a solvent (i.e., NMP) is added, the mixture is stirred in a vacuum mixer until the system becomes homogeneous, thus obtaining a positive slurry; the positive slurry is applied to both surfaces of an aluminum foil, dried at room temperature, then transferred to an oven for continued drying, then the positive electrode plate is obtained by cold pressing and cutting. 2. Production of a negative electrode plate

[0047] The specific manufacturing process is as follows: a negative active material (i.e., silicon-carbon) and graphite are mixed according to the mass ratio shown in Table 1, yielding a mixture; the mixture, a conductive agent (i.e., SWCNT), a conductive agent (i.e., SP), a thickening agent (i.e., CMC), a binder (i.e., SBR), and a binder (i.e., PAA) are mixed in a mass ratio of 96:0.05:0.95:0.2:1.5:1.3; deionized water is added, and the mixture is stirred in a vacuum mixer, yielding a negative slurry; the negative slurry is applied to both surfaces of a copper foil, dried at room temperature, then transferred to an oven for continued drying; the negative electrode plate with the electrode tab is then obtained by cold pressing and cutting.Depending on the direction of projection for the electrode tab, there are two types of electrode tabs; one of them is the one shown in . Fig. 1. The electrode tab shown protrudes upwards, and the other is the one in Fig. Figure 2 shows a laterally protruding electrode tab. In the present application, the width of the negative electrode plate is 200 mm, with the parameters, such as the projection direction of the electrode tab, the degree of compaction of the negative electrode plate, the areal density of the negative electrode plate, the length “L” of the negative electrode plate after cutting, the maximum distance “d” between the electrode tab and the end of the electrode plate, and the width of the electrode plate, shown in Table 1.

[0048] The above-mentioned negative active material, i.e., silicon carbon, is produced by a CVD deposition process. The process for producing the silicon carbon is as follows: Silane (~450 °C, silane decomposes to form silicon) gradually infiltrates the carbon skeleton through the adsorption capacity of the porous carbon at various temperatures; the surface of the silicon carbon is coated with acetylene carbon (~550 °C), forming a stable coating of a carbon layer / a-Si@a-PC structure. In the present application, the amount of silicon crystallites deposited in the porous carbon can be adjusted by controlling parameters such as the silane flow rate and the deposition time, thus controlling the percentage of silicon in the negative active material layer. 3. Procurement of a separator

[0049] For the separator in this embodiment, a separator with a coating on the carrier film is selected, and the carrier film is selected from polyethylene (PE), and the coating is a ceramic aluminium oxide layer. 4. Preparation of an electrolyte

[0050] The manufacturing process is as follows: in an argon-filled glovebox, fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and propylene carbonate (PC) are mixed in a mass ratio of 15:20:60:5, yielding an organic solvent; then, a thoroughly dried lithium salt (i.e., LiPF6) is dissolved in the organic solvent mixture; then, 0.5% of the electrolyte containing 1,3-propanesultone, 0.5% of the electrolyte containing tris(trimethylsilyl) phosphate, and 1% of the electrolyte containing vinyl sulfate are added; the mixture is stirred until complete dissolution, thus producing the electrolyte with a lithium salt concentration of 1.3 M. 5. Installation of a secondary battery

[0051] The specific process is as follows: the above positive electrode plate, the above separator, the above negative electrode plate are stacked in that order, with the separator located between the positive and negative electrode plates for insulation; then the electrode assembly is obtained by a stacking process; the electrode assembly is placed in an outer casing; after drying, the electrolyte is injected; and the lithium-ion secondary battery is obtained through processes such as conventional vacuum packing, standing, formation, and shaping. Table 1 Mass ratio of graphite to silicon-based material L Projection direction of the electrode tab b(%) d(mm) m(mm) density (g / cm³) 2 ) Degree of compaction (g / cm³) 3 ) Design 1 79,17:20,83 450 Protruding upwards 10 400 90 169,5 1,65 Design 2 94,17:5,83 450 Protruding upwards 2,8 325 178 169,5 1,65 embodiment 3 91,15:8,85 450 Protruding upwards 4,25 260 59 169,5 1,65 Design 4 89,58:10,42 450 Protruding laterally 5 450 100 169,5 1,65 Design 5 97,4:2,6 450 Protruding upwards 1,25 400 10 169,5 1,65 Design 6 94,79:5,21 450 Protruding upwards 2,5 240 10 169,5 1,65 Design 7 97,4:2,6 450 Protruding upwards 1,25 320 50 169,5 1,65 Design 8 94,79:5,21 450 Protruding upwards 2,5 313 180 169,5 1,65 Design 9 79,17:20,83 450 Protruding laterally 10 450 50 169,5 1,65 Design 10 66,67:33,33 450 Protruding upwards 16 450 9 169,5 1,65 Design 11 94,58:5,42 450 Protruding upwards 2,6 325 150 90,0 1,65 Design 12 94,58:5,42 450 Protruding upwards 2,6 325 150 300,0 1,65 embodiment 13 79,17:20,83 450 Protruding upwards 10 400 90 169,5 1,30 embodiment 14 79,17:20,83 450 Protruding upwards 10 400 90 169,5 2,30 Comparative example 1 66,67:33,33 450 Protruding upwards 16 450 5 169,5 1,65 Comparative example 2 97,4:2,6 450 Protruding upwards 1,25 450 450 169,5 1,65 Design 15 68,75:31,25 1100 Protruding upwards 15 960 12 169,5 1,65 Design 16 79,17:20,83 1100 Protruding laterally 10 1100 10 169,5 1,65 embodiment 17 97,4:2,6 1100 Protruding upwards 1,25 950 800 169,5 1,65 Design 18 97,4:2,6 1100 Protruding upwards 1,25 650 80 169,5 1,65 Comparative example 3 68,75:31,25 1100 Protruding upwards 15 1000 9,2 169,5 1,65 Comparative example 4 97,4:2,6 1100 Protruding upwards 1,25 1100 1100 169,5 1,65

[0052] The test procedures for the parameters b, the area density and the degree of compaction in Table 1 above are as follows: 1. The test procedure for the percentage content “b” of the element silicon in the negative active material layer is as follows.

[0053] The alkaline dissolution ICP method is used to test the silicon content in the negative electrode plate. Specifically, the battery is discharged at 0.33 C, washed with DMC solvent, soaked for 48 h, and dried at 60 °C. Powder is then scraped from the negative active material layer; the powder sample is weighed and placed in a nickel crucible pre-filled with potassium hydroxide. The sample surface is covered with a small amount of potassium hydroxide, two drops of ethanol are added, and the nickel crucible is heated in an electric furnace until the potassium hydroxide melts and dehydrates. It is then transferred to a muffle furnace at 1100 °C and kept molten for 8 h. The nickel crucible is removed and gently cooled. Next, the nickel crucible is placed in a 300 mL plastic beaker, hot water is added to the extract, and after the reaction, the crucible is washed.To acidify the extraction liquid, HCl is added, and hydrogen peroxide and hydrochloric acid are also added, forming an acid mixture for more complete conversion of silicon compounds to silicon ions. After cooling, the resulting substance is washed with water, transferred to a 100 mL volumetric flask, diluted to volume, and shaken well. After standing, a portion of the solution is transferred to another 100 mL volumetric flask, diluted to volume, shaken well, and allowed to settle until clear, thus obtaining the test solution. A blank sample solution is also prepared as a reference. This means that the same procedure is followed with the blank sample solution without the addition of a sample to prepare a reference sample, thereby eliminating any potential influences of the process.

[0054] An ICP test is performed on the test solution, the spectral wavelength for detecting the element is selected, and experimental conditions are set as follows: according to the sample characteristics and the ICP test performed on the test solution, the spectral wavelength for detecting the element Si is selected as 288.158 nm, and the Si content is determined by means of ICP.

[0055] 2. Measurement of the maximum distance “d” between the electrode tab and the end of the electrode plate in the longitudinal direction and the width “m” of the connection between the electrode tab and the electrode plate: The maximum distance “d” between the electrode tab and the end of the electrode plate in the longitudinal direction is in Fig. Figure 1 shows where “L” is the length of the electrode plate.

[0056] 3. Measurement of the surface density and degree of compaction of the negative active material layer: The battery is set to be tested at a state of 0% state of charge (SOC). It is then disassembled in a closed environment at approximately 25°C, yielding the negative electrode plate. This plate is soaked in DMC for 48 hours, with the DMC being replaced every 24 hours. The washed negative electrode plate is then placed in an oven at 70°C for 2 hours to remove any remaining DMC solvent, resulting in the test electrode plate.

[0057] A sampling device is used to take a sample from the test electrode plate, yielding circular pieces that are cut to form a solid surface, the area of ​​which is recorded as "S0". To ensure test accuracy, a central position of the electrode plate is selected for sampling, and three or more circular pieces are taken as parallel samples. The weight "m1" of each circular piece is measured using an electronic balance, and the thickness "h1" of the circular piece is measured with a micrometer. When measuring the thickness of the negative electrode plate with a micrometer, the micrometer spindle must be gradually moved towards the small anvil, clamping the electrode plate between it and the anvil.Graphite powder from the cross-section is cleaned after each measurement point, and the zero point is reset. Finally, an appropriate amount of deionized water is added to each of the three circular pieces, the coating is carefully wiped off with dust-free paper to expose the copper foil, followed by a 10-minute stand at room temperature (drying). After the copper foil has dried, the weights of the three copper foil pieces are measured and recorded as m0. Additionally, the thickness h0 of the circular piece is measured with a micrometer.

[0058] The thickness measurement procedure requires measuring the thickness at 5 points of each circular piece in the longitudinal direction; for each battery, 3 circular pieces must be tested, then the mean of all test results is determined.

[0059] Measurement of areal density: the density “A” obtained with the sampling device is calculated using “(m1 - m0) / S0”, where the value of “A” is the areal density of the negative active material layer. The unit for “m1” and “m0” is mg, and for “S0” the unit is cm³. 2 “ is, from “A” the unit “mg / cm²” 2 “ is, the value of “A” must be changed when converting to “g / m²”. 2 *0.1" be.

[0060] Measurement of the degree of compaction: The thickness of the coating is determined according to “h2 = h1 - h0”, and the degree of compaction of the negative active material layer is determined according to “A / h2”.

[0061] Performance tests are carried out on batteries for the embodiments and comparative examples under the conditions of the above parameters, with test procedures being as follows: 1. Fabrication for three electrodes and plating with lithium.

[0062] Several copper enamel wires with a diameter of 40 µm are produced, followed by a 3-hour soak in 98% sulfuric acid, then a 5-minute wash with anhydrous ethanol, then a 20-minute soak in dilute 20% hydrochloric acid, then a 5-minute wash with deionized water, and finally, the treated copper wire is placed in a drying oven at 50 °C until the surface of the copper wire is dry. This treated copper wire is used as the reference electrode of the battery.

[0063] The positive electrode, the separator, the reference electrode, the separator and the negative electrode are assembled in this order, and the electrode tab of the reference electrode is led out of the top of the battery.

[0064] The plating of the reference electrode with lithium is carried out using a button cell charge-discharge device from Land as follows: (1) Forward plating: The electrode connection mode is positive electrode + reference electrode, a current of 0.1 mA, a duration of 5 h; (2) Backward plating of lithium: The electrode connection mode is negative electrode + reference electrode, a current of 0.1 mA and a duration of 5 h. 2. Fast charging performance test.

[0065] The testing procedure is as follows: a. Charge the battery with a constant current of 0.33 C until the upper voltage limit of 4.25 V is reached, then charge with a constant voltage until the forward current is less than or equal to 0.05 C, and discharge; Repeat the above steps 3 times, using the discharge capacity of the third time as the discharge capacity of the battery; b: Charging the battery at 0.33 C up to a SOC of 10% based on the battery capacity in step a, to be recorded as T0; c: Then, at 4 C, 3.5 C, 3.0 C, 2.75 C, 2.5 C, 2.25 C, 2.0 C, 1.75 C, 1.5 C, 1.25 C, 1 C, 0.75 C, 0.5 C, 0.33 C, monitor and adjust the jump at the reference auxiliary potential of the negative electrode of 0 V (i.e., for example, for charging at 4 C, when the reference auxiliary potential of the negative electrode of 0 V is reached, the jump occurs, followed by the start of charging at 3.5 C), record the duration of charging the battery to 80% of the SOC as T1, where T1-T0 is the fast charging time in the unit "min", at a test temperature of 25 ± 2 °C. 3. Energy density test.

[0066] The testing procedure is as follows: a: Charge the battery with a constant current of 0.33 C until the upper voltage limit of 4.25 V is reached, then charge with a constant voltage until the forward current is less than or equal to 0.05 C, and discharge; Repeat the above steps 3 times, using the discharge energy of the third time as the discharge energy of the battery; b: Measuring the weight “M” of the battery with the electronic scale and c: Calculating the energy density using weight: E / M in the unit "Wh / kg".

[0067] The fast charging time and energy density of batteries for different designs and comparative examples are listed in Table 2 below. Table 2 / L b d m Lgmd×b Fast charging time (min) Energy density (Wh / kg) Design 1 450 10 400 90 -1,6478 12,9 343,2 Design 2 450 2,8 325 178 -0,7086 11,5 299,5 embodiment 3 450 4,25 260 59 -1,2725 12,3 307,3 Design 4 450 5 450 100 -1,3522 12,5 312,9 Design 5 450 1,25 400 10 -1,6990 14,2 275,0 Design 6 450 2,5 240 10 -1,7782 16,3 295,6 Design 7 450 1,25 320 50 -0,9031 11,7 274,0 Design 8 450 2,5 313 180 -0,6382 11,3 279,1 Design 9 450 10 450 50 -1,9542 28,1 345,1 Design 10 450 16 450 9 -2,9031 37,1 361,0 Design 11 450 2,6 325 150 -0,7508 11,2 253,0 Design 12 450 2,6 325 150 -0,7508 16,1 370,0 embodiment 13 450 10 400 90 -1,6478 15,7 321,3 embodiment 14 450 10 400 90 -1,6478 15,3 324,2 Comparative example 1 450 16 450 5 -3,1584 46,1 359,5 Comparative example 2 450 1,25 450 450 -0,0969 10,9 243,0 Design 15 1100 15 960 12 -3,0792 49 379,0 Design 16 1100 10 1100 10 -3,0414 47,5 358,0 embodiment 17 1100 1,25 950 800 -0,1715 25,6 306,7 Design 18 1100 1,25 650 80 -1,0067 29,9 311,1 Comparative example 3 1100 15 1000 9,2 -3,2123 61,3 383,0 Comparative example 4 1200 1,25 1200 1200 -0,0969 39,7 305,1

[0068] The data results in Tables 1 and 2 show that: through comprehensive control of b, d and m such that −3.1≤Lgmd×b≤−0.11 If this requirement is met, ensuring a relatively high energy density, the battery's fast charging performance can also be guaranteed. In particular, further optimization of the value of Lgmd×b so that it is controlled in the range of -1.8 to -0.7, batteries with a higher energy density and better fast-charging performance are obtained. In particular, for the scheme where the length “L” of the long edge of the negative electrode plate is 450 mm, the fast-charging time is ≤45 min, preferably ≤20 min; the energy density is ≥250 Wh / kg, preferably ≥270 Wh / kg, more preferably ≥290 Wh / kg. For the scheme where the length “L” of the long edge of the negative electrode plate is 1000–1100 mm, the fast-charging time is ≤50 min, preferably ≤30 min; the energy density is ≥300 Wh / kg, preferably ≥310 Wh / kg.

[0069] Obviously, the embodiments described above are merely examples for clear illustration and do not represent limitations on the implementations. For a typical engineer in this field, other forms of modification or variation can be made based on the above description. A complete list of all implementation methods is neither necessary nor possible here. The obvious modifications or variations derived from this remain within the scope of protection of the present invention.

Claims

[1] Battery comprising a battery cell, the battery cell comprising a negative electrode plate and an electrode tab arranged on the negative electrode plate; wherein a negative active material layer of the negative electrode plate contains silicon, the mass percent of silicon in the negative active material layer being “b” in units of “%”; wherein a maximum distance between the electrode tab and an end of the negative electrode plate being “d” in units of “mm” in a direction parallel to a long edge of the negative electrode plate; wherein a projection direction of the electrode tab being a first direction, a distance of a connection between the electrode tab and the negative electrode plate in a direction perpendicular to the first direction being equal to a width “m” of the electrode tab being equal to units of “mm”, and “b”, “d”, and “m” satisfying the following relationship: −3,1≤Lgmd×b≤−0,11. [2] Battery according to claim 1, wherein the value of Lgmd×b in the range of -1.8 to -0.

7. [3] Battery according to claim 1 or 2, wherein the value of ‘b’ is in the range of 1.25 to 16. [4] Battery according to claim 3, wherein the value of ‘b’ is in the range of 2.5 to 10. [5] Battery according to any of the preceding claims, wherein the value of ‘d’ is in the range of 42 to 1000. [6] Battery according to claim 5, and / or the value of “d” is in the range of 250 to 450. [7] Battery according to any of the preceding claims, wherein the value of ‘m’ is in the range of 9 to 960. [8] Battery according to claim 7, wherein the value of “m” is in the range of 50 to 180. [9] Battery according to one of the preceding claims, wherein the areal density of the negative active material layer is in the range of 90 to 300 g / m² 2 lies. [10] Battery according to one of the preceding claims, wherein the density of the negative active material layer is in the range of 1.2 to 2.3 g / cm³ 3 lies. [11] Battery according to one of the preceding claims, wherein the electrode tab projects from the long edge of the negative electrode plate and in a direction perpendicular to the projection direction of the electrode tab, and the ratio between the width of the electrode tab and the width of the negative electrode plate is greater than or equal to 0.5 and less than or equal to 1. [12] Battery according to any of the preceding claims, wherein the length ‘L’ along the long edge of the negative electrode plate is greater than or equal to 300 mm. [13] Battery according to any of the preceding claims wherein the battery cell is a stacked battery cell. [14] Battery according to one of the preceding claims, wherein, in the case of a positive electrode plate enclosed in the battery cell, the positive active material used is LiNi x Co y Mn z O2 is, whereby 1>x≥0.5,x+y+z=1. [15] Battery according to claim 14, comprising a separator, for example PP, PE and / or PP / PE, between the positive electrode plate and the negative electrode plate, an outer casing, and an electrolyte with an electrolyte salt and a solvent and optional additives, the battery cell and the electrolyte are arranged in the outer casing. [16] Electrochemical device comprising the battery according to any one of claims 1 to 15. [17] Electrical device comprising the electrochemical device according to claim 16.

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