Secondary battery cell and electric device

Abstract

A secondary battery cell and an electric device. The secondary battery cell comprises a negative electrode sheet, and the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector; the negative electrode film layer comprises a solid electrolyte material and a graphite material; the negative electrode film layer comprises a first region and a second region, and the second region is located between the first region and the negative electrode current collector; and the content of the solid electrolyte material in the first region is less than the content of that in the second region.

Description

Secondary battery cells and electrical devices

[0001] Cross-references to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202510080408.2, filed on January 17, 2025, entitled “Secondary Battery Cell and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of battery technology, and in particular to a secondary battery cell and an electrical device. Background Technology

[0004] In recent years, with the increasingly wide application of rechargeable batteries, individual rechargeable battery cells have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in various fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, and aerospace. With the application and promotion of rechargeable batteries, people have increasingly higher requirements for their rate performance and cycle performance.

[0005] Therefore, improving the rate performance and cycle performance of secondary batteries has become an urgent technical problem to be solved. Summary of the Invention

[0006] This disclosure is made in view of the above-mentioned problems, and its object is to provide a secondary battery cell and an electrical device, the secondary battery cell having improved rate performance and cycle performance.

[0007] To achieve the above objectives, the first aspect of this disclosure provides a secondary battery cell, including a negative electrode sheet, the negative electrode sheet including a negative current collector and a negative electrode film layer located on at least one side of the negative current collector;

[0008] The negative electrode film layer includes a solid electrolyte material and a graphite material; the negative electrode film layer includes a first region and a second region, with the second region located between the first region and the negative electrode current collector;

[0009] The content of solid electrolyte material in the first region is lower than that in the second region. This improves the contact between the graphite material and the solid electrolyte material, thereby enhancing the rate performance and cycle performance of the secondary battery cells.

[0010] In some implementations, the solid electrolyte material accounts for 20% to 50% of the total mass of the negative electrode film. This is beneficial for balancing the rate performance, cycle performance, and energy density of the secondary battery cell.

[0011] In some implementations, the solid electrolyte material accounts for 10% to 50% of the total mass of the first region. This is beneficial for further improving the rate performance and cycle performance of the secondary battery cells.

[0012] In some implementations, the solid electrolyte material accounts for 30% to 50% of the total mass of the second region. This is beneficial for further improving the rate performance and cycle performance of the secondary battery cells.

[0013] In some embodiments, the ratio of the content of solid electrolyte material in the first region to the content of solid electrolyte material in the second region is greater than or equal to 0.2 and less than 1. This is beneficial for balancing the rate performance, cycle performance, and energy density of the secondary battery cell.

[0014] In some embodiments, the solid electrolyte material includes one or more of sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolyte materials, and polymer solid electrolyte materials. This can improve the diffusion rate of active ions at the interface between the graphite material and the solid electrolyte, which is beneficial for reducing polarization and improving the rate performance and cycle performance of the secondary battery cell.

[0015] In some embodiments, the solid electrolyte material includes Li d MX d+3 The material includes 1≤d≤6, M including one or more of Al, Ga, In, Y, Zr, Nb, Sc, Ti, Mn, and La, and X including one or more of halogens, S, O, and P.

[0016] In some embodiments, the volumetric particle size distribution Dv50 of the solid electrolyte material is 500 nm to 5 μm. This is beneficial for improving the rate performance and cycle performance of the secondary battery cells.

[0017] In some embodiments, the OI value of the graphite material is 1 to 6. This is beneficial for improving the contact between the graphite material and the solid electrolyte material, thereby improving the rate performance and cycle performance of the secondary battery cell.

[0018] In some embodiments, the mass ratio of graphite material to solid electrolyte material in the first region is greater than that in the second region. This improves the contact between the graphite material and the solid electrolyte material, thereby enhancing the rate performance and cycle performance of the secondary battery cell.

[0019] In some embodiments, the mass ratio of graphite material to solid electrolyte material in the first region is (7:3) to (9:1). This is beneficial for balancing the rate performance, cycle performance, and energy density of the secondary battery cell.

[0020] In some embodiments, the mass ratio of graphite material to solid electrolyte material in the second region is (5:5) to (7:3). This is beneficial for balancing the rate performance, cycle performance, and energy density of the secondary battery cell.

[0021] In some implementations, the thickness of the single-sided negative electrode film is 70 μm to 250 μm. This is beneficial for improving the energy density of the secondary battery cell.

[0022] In some embodiments, the thickness ratio of the first region to the second region is (1:1) to (1:3). This is beneficial for improving the energy density and cycle performance of the secondary battery cell.

[0023] In some implementations, the porosity of the negative electrode film is 20% to 40%. This is beneficial for improving the rate performance of the secondary battery cell.

[0024] In some implementations, the porosity of the first region is greater than that of the second region. This is beneficial for improving the rate performance and cycle performance of the secondary battery cell.

[0025] In some embodiments, the volumetric particle size distribution (Dv50) of the graphite material is 1 μm to 20 μm. This is beneficial for improving the rate performance of the secondary battery cell.

[0026] In some embodiments, the volumetric particle size distribution (Dv90-Dv10) / Dv50 of the graphite material is 1 to 3. This is beneficial for improving the rate performance of the secondary battery cell.

[0027] In some implementations, the specific surface area of ​​the graphite material is 0.5 m². 2 / g~5m 2 / g. This is beneficial for improving the capacity and energy density of secondary battery cells.

[0028] In some embodiments, the graphitization degree of the graphite material is 91% to 96%. This is beneficial for improving the energy density of the secondary battery cell.

[0029] In some embodiments, at least a portion of the graphite material has a carbon coating layer on its surface. This is beneficial for improving the rate performance of the secondary battery cell.

[0030] In some implementations, the graphite material includes secondary particles. This is beneficial for improving the rate performance of the secondary battery cells.

[0031] In some implementations, the graphite material includes one or more of artificial graphite and natural graphite.

[0032] In some embodiments, the secondary battery cell also includes a positive electrode and an electrolyte membrane;

[0033] The electrolyte membrane is located between the positive electrode and the negative electrode.

[0034] A second aspect of this disclosure provides an electrical device including a secondary battery cell according to the first aspect of this disclosure. Attached Figure Description

[0035] Figure 1 is a schematic diagram of the structure of the negative electrode sheet according to an embodiment of the present disclosure.

[0036] Figure 2 is a schematic diagram of a secondary battery cell according to an embodiment of the present disclosure.

[0037] Figure 3 is an exploded view of a secondary battery cell according to an embodiment of the present disclosure shown in Figure 2.

[0038] Figure 4 is a schematic diagram of a battery module according to an embodiment of the present disclosure.

[0039] Figure 5 is a schematic diagram of a battery pack according to one embodiment of the present disclosure.

[0040] Figure 6 is an exploded view of a battery pack according to an embodiment of the present disclosure, as shown in Figure 5.

[0041] Figure 7 is a schematic diagram of a power supply device using a battery device according to an embodiment of the present disclosure.

[0042] Explanation of reference numerals in the attached drawings: 1 Battery pack; 2 First housing; 3 Second housing; 4 Battery module; 5 Secondary battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly; 10 Negative electrode sheet; 101 Negative current collector; 102 Negative electrode film; 103 First region; 104 Second region. Detailed Implementation

[0043] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the secondary battery cell and power-consuming device of this disclosure. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0044] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this disclosure can be combined to form new technical solutions.

[0046] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions.

[0047] Unless otherwise specified, all steps of this disclosure may be performed sequentially or randomly, preferably sequentially. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if it is mentioned that the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0048] Unless otherwise specified, the terminology used in this disclosure has the common meaning as commonly understood by those skilled in the art.

[0049] Unless otherwise specified, the values ​​of the parameters mentioned in this disclosure can be determined using various test methods commonly used in the art, for example, according to the test methods given in this disclosure.

[0050] In traditional liquid-state rechargeable battery systems, graphite anode materials are mature commercial products with low cost and stable chemical properties. Therefore, applying them to solid-state battery systems could expedite the practical application of all-solid-state batteries. Unlike traditional liquid-state battery systems where lithium ions are stored through contact between the electrolyte and the active material, solid-state batteries typically use a mixture of graphite and electrolyte materials as the anode material. This mixture creates a solid-solid interface between the graphite and electrolyte materials, exhibiting high interfacial impedance and limited ion transport paths. Therefore, to ensure effective contact between the graphite and electrolyte materials, high pressure is often required externally to facilitate this contact. However, maintaining high external pressure is difficult in practical applications. Therefore, how to maintain effective contact between graphite and electrolyte materials under low or no pressure is a pressing technical problem that needs to be solved.

[0051] In related technologies, the contact between graphite and electrolyte materials is improved by coating graphite with amorphous carbon. However, in thick electrodes, the electrolyte distribution is uneven and polarization occurs, resulting in poor active ion transport capacity. Therefore, the improvement methods in related technologies have limited effect on improving the contact between graphite and solid electrolyte materials, and they still have problems with poor rate performance and cycle performance.

[0052] Based on this, this disclosure proposes a novel secondary battery cell and its power application device. The secondary battery cell of this disclosure has improved rate performance and cycle performance. The following provides a more detailed description of this disclosure and its optional embodiments.

[0053] Secondary battery cell

[0054] The first aspect of this disclosure provides a secondary battery cell, including a negative electrode sheet, as shown in FIG1. ​​The negative electrode sheet 10 includes a negative current collector 101 and a negative electrode film layer 102 located on at least one side of the negative current collector. The negative electrode film layer includes a solid electrolyte material and a graphite material. The negative electrode film layer 102 includes a first region 103 and a second region 104. The second region 104 is located between the first region 103 and the negative current collector 101. The content of solid electrolyte material in the first region 103 is less than the content of solid electrolyte material in the second region 104.

[0055] In this disclosure, by setting the content of solid electrolyte material in the second region near the negative electrode current collector to be greater than the content of solid electrolyte material in the first region far from the negative electrode current collector, the solid electrolyte material can better fill the gaps between graphite materials in the second region near the negative electrode current collector of the negative electrode film layer without applying external pressure to the secondary battery cell or with a small amount of external pressure. This can improve the contact between the graphite material and the solid electrolyte material, thereby improving the rate performance and cycle performance of the secondary battery cell.

[0056] In this disclosure, the content of solid electrolyte can be reversed in the following way: the negative electrode sheet can be cut into a sample of a certain size (e.g., 2cm × 2cm), and the negative electrode sheet can be fixed on the sample stage using paraffin wax; the sample stage can be installed in the sample holder and locked in place, the power of the argon ion cross-section polisher (e.g., the IB-09010CP argon ion cross-section polisher of JEOL Corporation of Japan) can be turned on and a vacuum can be drawn (e.g., 10-4 Pa), the argon flow rate (e.g., 0.15 MPa), voltage (e.g., 8 kV) and polishing time (e.g., 2 h) can be set, and the sample stage can be adjusted to the swing mode to start polishing; a region can be randomly selected in the sample to be tested for scanning (e.g., according to JY / T010-1996, scanning can be performed using a scanning electron microscope), and the ion polished cross-sectional morphology (CP) image of the negative electrode sheet can be obtained at a certain magnification (e.g., 1000x). The boundary between the first and second regions is clearly observed on the CP image, and the distribution of graphite material in the first and second regions is also observed. Using specific software, the area ratio of graphite material in the first region and the area ratio of graphite material in the second region can be calculated. The area ratio of graphite material can reflect the content of graphite material. In this way, the relative content of solid electrolyte material in the first and second regions can be determined.

[0057] In some embodiments, the mass percentage of solid electrolyte material is 20% to 50%, optionally 30% to 40%, based on the total mass of the negative electrode film. This is beneficial for balancing the rate performance, cycle performance, and energy density of the secondary battery cell. Exemplarily, the mass percentage of solid electrolyte material, based on the total mass of the negative electrode film, is a value within a range of 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any combination thereof.

[0058] In some embodiments, the mass percentage of solid electrolyte material is 10% to 50% based on the total mass of the first region, optionally 15% to 30%. This is beneficial for further improving the rate performance and cycle performance of the secondary battery cell. Exemplarily, the mass percentage of solid electrolyte material based on the total mass of the first region is a value within a range of 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, or any combination thereof.

[0059] In some embodiments, the mass percentage of solid electrolyte material is 30% to 50%, optionally 35% to 40%, based on the total mass of the second region. This is beneficial for further improving the rate performance and cycle performance of the secondary battery cell. Exemplarily, the mass percentage of solid electrolyte material based on the total mass of the second region is a value within a range of 30%, 35%, 40%, 45%, 50%, or any combination thereof.

[0060] In some embodiments, the ratio of the content of solid electrolyte material in the first region to the content of solid electrolyte material in the second region is greater than or equal to 0.2 and less than 1, optionally ranging from 0.25 to 0.6. This is beneficial for balancing the rate performance, cycle performance, and energy density of the secondary battery cell. For example, the ratio of the content of solid electrolyte material in the first region to the content of solid electrolyte material in the second region is a value within a range of 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or any combination thereof.

[0061] In some embodiments, the solid electrolyte material includes one or more of sulfide solid electrolyte materials, oxide solid electrolyte materials, and polymer solid electrolyte materials. Sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolyte materials, and polymer solid electrolytes have high ionic conductivity, which can improve the diffusion rate of active ions at the interface between the graphite material and the solid electrolyte, thus reducing polarization and improving the rate performance and cycle performance of the secondary battery cell. For example, the sulfide solid electrolyte includes at least one of binary compounds such as Li6PS5Cl, Li2S-GeS2, Li2S-P2S5, and Li2S-SiS2, and a ternary compound such as Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.). The oxide solid electrolyte includes lithium lanthanum zirconium oxide series oxides or tin oxide solid electrolytes. The halide solid electrolyte includes chloride solid electrolytes; optionally, the chloride solid electrolyte includes Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.6 In 0.6 Zr 0.4 Cl6, Li 1.5 ZrOCl 3.5 Li3InO 0.2 Cl 5.6 LiNbOCl4, Li 1.5 AlOCl 2.5 、Li3In 0.5 Y 0.5One or more of Cl6. Polymer solid electrolytes include one or more of PEO (polyethylene oxide), PAN (polyacrylonitrile), and PMMA (polymethyl methacrylate).

[0062] In some embodiments, the solid electrolyte material includes Li d MX d+3 The material includes 1≤d≤6, M including one or more of Al, Ga, In, Y, Zr, Nb, Sc, Ti, Mn, and La, and X including one or more of halogens, S, O, and P.

[0063] In some embodiments, the volumetric particle size distribution Dv50 of the electrolyte material is 500 nm to 5 μm, optionally 600 nm to 1 μm. A volumetric particle size distribution Dv50 within this range allows the electrolyte material to better fill the voids between the graphite materials in the negative electrode film, thereby improving the contact between the graphite materials and the solid electrolyte material, which is beneficial for improving the rate performance and cycle performance of the secondary battery cell. Exemplarily, the volumetric particle size distribution Dv50 of the electrolyte material is a value within a range of 500 nm, 750 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or any combination thereof.

[0064] In some embodiments, the OI value of the graphite material is between 1 and 6. An OI value within this range reflects high isotropy of the graphite material. This, on the one hand, is beneficial for improving the ion-conducting ability of graphite; on the other hand, it can reduce interlayer slippage and elastic deformation, which is conducive to further improving the contact between the graphite material and the solid electrolyte material, thereby further improving the rate performance and cycle performance of the secondary battery cell. For example, the OI value of the graphite material is any value within the range of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or any combination thereof.

[0065] In this disclosure, the term "OI value" has a meaning known in the art and can be tested using instruments and methods known in the art. For example, it can be tested using an X-ray powder diffractometer (X'pert PRO), and the test can be performed in accordance with JIS K 0131-1996 and JB / T 4220-2011. Specifically, the negative electrode active material is obtained by scraping off the negative electrode film layer, and the X-ray diffraction pattern of graphite is obtained by XRD testing of the negative electrode active material. According to OI value = I 004 / I 110 Calculate the OI value of graphite. Where I... 004 I is the integrated area of ​​the diffraction peak of the carbon 004 crystal plane in graphite.110 This represents the integrated area of ​​the diffraction peak on the 110 crystal plane of crystalline carbon in graphite. In the X-ray diffraction analysis test disclosed herein, a copper target can be used as the anode target, CuKα rays can be used as the radiation source, the ray wavelength scanning 2θ angle range is 20° to 80°, and the scanning rate is 4° / min.

[0066] In some embodiments, the mass ratio of graphite material to solid electrolyte material in the first region 103 is greater than that in the second region 104. By setting a higher mass ratio of graphite material to solid electrolyte material in the second region, closer to the negative electrode current collector, the solid electrolyte material can better fill the gaps between the graphite materials in the second region, thereby further improving the contact between the graphite material and the solid electrolyte material, which is more conducive to improving the rate performance and cycle performance of the secondary battery cell.

[0067] In some embodiments, the mass ratio of graphite material to solid electrolyte material in the first region is (7:3) to (9:1), optionally (8:2) to (9:1). This ensures good contact between the graphite material and the solid electrolyte material in the first region and also improves the energy density of the secondary battery cell. Therefore, when the mass ratio of graphite material to solid electrolyte material in the first region is within the above range, it is possible to achieve a balance between the rate performance, cycle performance, and energy density of the secondary battery cell. For example, the mass ratio of graphite material to solid electrolyte material in the first region is a value within the range of 7:3, 7.5:2.5, 8:2, 8.5:1.5, 9:1, or any combination thereof.

[0068] In some embodiments, the mass ratio of graphite material to solid electrolyte material in the second region is (5:5) to (7:3), optionally (6:4) to (7:3). This improves both the contact between the graphite material and the solid electrolyte material in the second region and increases the energy density of the secondary battery cell. Therefore, a mass ratio of graphite material to solid electrolyte material in the second region within the aforementioned range can achieve a balance between the rate performance, cycle performance, and energy density of the secondary battery cell. For example, the mass ratio of graphite material to solid electrolyte material in the first region is a value within a range of 5:5, 5.5:4.5, 6:4, 6.5:3.5, 7:3, or any combination thereof.

[0069] In some embodiments, the thickness ratio of the first region to the second region is (1:1) to (1:3), and can be selected as (1:1.5) to (1:2.5). This helps to reduce the porosity of the negative electrode film and increase the contact area between the graphite material and the electrolyte material, thereby improving the energy density and cycle performance of the secondary battery cell. Exemplarily, the thickness ratio of the first region to the second region is a value within a range of 1:1, 1:1.5, 1:2, 1:2.5, 1:3, or any combination thereof.

[0070] In some embodiments, the thickness of the single-sided negative electrode film is 70 μm to 250 μm, optionally 200 μm to 230 μm. This allows for thick coating, which is beneficial for improving the energy density of the secondary battery cell. Exemplarily, the thickness of the negative electrode film is a value within a range of 70 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, or any combination thereof.

[0071] In some embodiments, the thickness of the first region is 20 μm to 100 μm, optionally 60 μm to 100 μm. This is beneficial for improving both the rate performance and energy density of the secondary battery cell. For example, the cold-pressed thickness of the first region is a value within a range of 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or any combination thereof.

[0072] In some embodiments, the thickness of the second region is 50 μm to 150 μm, optionally 100 μm to 140 μm. This is beneficial for balancing the rate performance and cycle performance of the secondary battery cell. For example, the cold-pressed thickness of the second region is a value within a range of 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, or any combination thereof.

[0073] In this disclosure, the thickness ratio of the first region and the second region can be measured in the following manner: The first region and the second region are peeled off from the negative electrode current collector, the peeled-off negative electrode active layer is fixed on the sample stage, the sample stage is installed and locked in place on the sample holder, the power of the argon ion cross-section polisher (e.g., JEOL IB-09010CP argon ion cross-section polisher) is turned on and a vacuum is applied (e.g., 10⁻⁷ Pa), the argon flow rate is set (e.g., 0.12 MPa) and the polishing time (e.g., 90 min), and the sample stage is adjusted to the swing mode to begin polishing. After polishing, the thickness of the cross-section of the first region and the second region is measured using a scanning electron microscope.

[0074] In some embodiments, the porosity of the negative electrode film is 20% to 40%. This provides the negative electrode film with a suitable ion transport rate, which is beneficial for improving the rate performance of the secondary battery cell. Exemplarily, the porosity of the negative electrode film is a value within a range of 20%, 25%, 30%, 35%, 40%, or any combination thereof.

[0075] In some embodiments, the porosity of the first region is greater than that of the second region. This reflects a closer contact between the solid electrolyte material and the graphite material in the second region, meaning better contact between the solid electrolyte material and the graphite material in the second region, which further contributes to improving the rate performance and cycle performance of the secondary battery cell.

[0076] In some embodiments, the porosity of the first region is 25% to 50%, optionally 30% to 40%. A porosity within this range provides the first region with suitable ion-conducting capacity, which is beneficial for improving the charging capacity of the first region and further improves the rate performance of the secondary battery cell. Exemplarily, the porosity of the first region is a value within a range of 25%, 30%, 35%, 40%, 45%, 50%, or any combination thereof.

[0077] In some embodiments, the porosity of the second region is 20% to 30%, optionally 25% to 30%. A porosity within this range provides the second region with suitable ion-conducting capacity, which is beneficial for improving the charging capacity of the second region and further improves the rate performance of the secondary battery cell. Exemplarily, the porosity of the second region is a value within a range of 20%, 22%, 25%, 26%, 28%, 30%, or any combination thereof.

[0078] In this disclosure, the porosity of the negative electrode film layer has a meaning known in the art and can be determined using instruments and methods known in the art. For example, it can be determined using a true density meter according to GB / T 24586-2009. Specifically: the negative electrode film layer is cut into 3mm × 3mm pieces, and the apparent volume V0 of the sample is measured (the apparent volume of the sample is the thickness of the sample × the area of ​​the sample). Then, the true volume of the sample is measured using a true density meter. Specifically, the sample is placed in the sample test chamber, and nitrogen gas is introduced into the sample test chamber. The sample test chamber is connected to the reference chamber, and the pressure after stabilization is recorded. By detecting the pressure before the reference chamber and the sample chamber are connected and the pressure after the connection is stabilized, the pore volume is calculated according to Bohr's law PV = nRT. The porosity of the sample = pore volume / apparent volume.

[0079] In some embodiments, the volumetric particle size distribution Dv50 of the graphite material is 1 μm to 20 μm, optionally 8 μm to 15 μm. When the volumetric particle size distribution Dv50 of the graphite material is within the above range, the graphite material can be graded with the solid electrolyte material, thereby reducing the voids between the graphite material and the solid electrolyte material, which is beneficial to improving the rate performance of the secondary battery cell. Exemplarily, the volumetric particle size distribution Dv50 of the graphite material is a value within the range of 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, or any combination thereof.

[0080] In some embodiments, the volumetric particle size distribution (Dv90-Dv10) / Dv50 of the graphite material is 1 to 3. When the volumetric particle size distribution (Dv90-Dv10) / Dv50 of the graphite material is within the above range, the particle size distribution of the graphite material is relatively narrow, which is beneficial for gradation with the solid electrolyte material, thereby giving the negative electrode film a suitable pore structure, which is beneficial for improving the ion and electron transport performance of the negative electrode film, and thus beneficial for improving the rate performance of the secondary battery cell. For example, the volumetric particle size distribution (Dv90-Dv10) / Dv50 of the graphite material is a value within the range of 1, 1.3, 1.6, 1.9, 2.1, 2.3, 2.6, 3, or any combination thereof.

[0081] In some embodiments, the volumetric particle size distribution Dv90 of the graphite material is 1 μm to 20 μm, and optionally, it is 14 μm to 18 μm.

[0082] In some embodiments, the volumetric particle size distribution Dv10 of the graphite material is 1 μm to 20 μm, and optionally, it is 4 μm to 8 μm.

[0083] In this disclosure, the volumetric particle size distributions "Dv10", "Dv50", and "Dv90" have meanings known in the art, representing the particle size corresponding to a cumulative volumetric distribution percentage of 10%, 50%, and 90%, respectively, and can be determined using instruments and methods known in the art. For example, they can be determined using a laser particle size analyzer, referring to GB / T 19077-2016. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK.

[0084] In some implementations, the specific surface area of ​​the graphite material is 0.5 m². 2 / g~5m 2 / g, optionally, is 0.85m 2 / g~1.35m 2 / g. This facilitates the effective insertion and extraction of active ions between the graphite material layers, thereby improving the capacity and energy density of the secondary battery cell. For example, the specific surface area of ​​the graphite material is 0.5m². 2 / g, 1m 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g、5m 2 / g or a range between the values ​​of either / g or any two of them.

[0085] In this disclosure, the "specific surface area" of graphite materials has a meaning known in the art and can be measured using instruments and methods known in the art. For example, the specific surface area of ​​solid materials can be determined by referring to the GB / T 19587-2004 standard for determination of specific surface area of ​​solid materials by gas adsorption BET method, using the nitrogen adsorption specific surface area analysis test method, and calculated using the BET (Brunauer Emmett Teller) method. The nitrogen adsorption specific surface area analysis test can be performed using a Tri Star II 3020 specific surface area and porosity analyzer from Micromeritics, USA.

[0086] In some embodiments, the graphitization degree of the graphite material is 91% to 96%. A graphitization degree within this range is beneficial for improving the energy density of the secondary battery cell. Exemplarily, the graphitization degree of the graphite material is a value between 91%, 92%, 93%, 94%, 95%, 96%, or any combination thereof.

[0087] In this disclosure, "degree of graphitization" has a meaning known in the art and can be tested using instruments and methods known in the art. For example, it can be tested using an X-ray diffractometer (such as a Bruker D8 Discover), and the test can be performed with reference to JIS K 0131-1996 and JB / T 4220-2011. The average interlayer spacing d002 of the C(002) crystal plane in the material's crystal structure can be obtained, and then the degree of graphitization can be calculated using the formula: degree of graphitization g = (0.344 - d002) / (0.344 - 0.3354) × 100%. Wherein, d002 is the average interlayer spacing of the C(002) crystal plane in the material's crystal structure, expressed in nanometers (nm).

[0088] In some embodiments, at least a portion of the graphite material has a carbon coating layer on its surface. This reduces the anisotropy of the graphite material and decreases the porosity between graphite particles, thereby improving the rate performance of the secondary battery cells. Optionally, the carbon coating layer may be made of one or more of soft carbon and hard carbon.

[0089] In some embodiments, the graphite material includes secondary particles. This helps to reduce the anisotropy of the graphite material, thereby improving its ion-conducting ability and consequently enhancing the rate performance of the secondary battery cell.

[0090] In some embodiments, the negative electrode film layer further includes an adhesive, which may include nitrile rubber, styrene-butadiene rubber, or silicone rubber.

[0091] In some embodiments, the binder accounts for 1% to 5% of the mass of the negative electrode film, for example, 2%. This allows for improved stability of the negative electrode sheet without affecting the energy density of the secondary battery cell, thus balancing the cycle performance and energy density of the secondary battery cell.

[0092] In some implementations, the graphite material includes one or more of artificial graphite and natural graphite.

[0093] In some embodiments, the above-mentioned graphite material can be prepared by the following exemplary steps:

[0094] 1) Raw material preparation: Select suitable graphite raw materials (such as natural graphite or artificial graphite) and coating layer raw materials (such as one or more of coal tar pitch, petroleum pitch, soft carbon, hard carbon, lanthanum zirconium lithium oxide);

[0095] 2) Pretreatment of graphite raw materials: The graphite raw materials are purified to remove impurities, and then spheroidized or crushed to obtain appropriate particle size;

[0096] 3) Pretreatment of coating material: The coating material is heated to a certain temperature to make it more fluid and easier to mix with graphite;

[0097] 4) Mixing and coating: The pretreated graphite raw material is mixed with the heated coating material. Usually, the coating material is uniformly coated on the surface of the graphite raw material by stirring, grinding and other methods.

[0098] 5) Heat treatment: The mixed materials are heat-treated at 300℃~1500℃ for 1h~4h under an inert atmosphere to obtain graphite materials.

[0099] In some embodiments, the secondary battery cell further includes a positive electrode and an electrolyte membrane; the electrolyte membrane is located between the positive and negative electrode. The electrolyte membrane can be any of a solid electrolyte membrane, a gel electrolyte membrane, or a semi-solid electrolyte membrane.

[0100] Typically, a single rechargeable battery cell includes a positive electrode, a negative electrode, and an electrolyte membrane. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte membrane, positioned between the positive and negative electrodes, serves to conduct ions and prevent short circuits between the positive and negative electrodes.

[0101] Negative electrode sheet

[0102] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, wherein the negative electrode film layer is the negative electrode film layer in the above embodiment.

[0103] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0104] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0105] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, solid electrolyte material, conductive agent, binder and any other components, in a solvent (e.g. xylene) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0106] Positive electrode sheet

[0107] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material, which may be a positive electrode active material known in the art and is not particularly limited.

[0108] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0109] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0110] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this disclosure is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0111] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content refers to the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery system, the molar Li content changes after charge-discharge cycles.

[0112] In the examples of positive electrode active materials disclosed herein, the molar content of oxygen is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of oxygen will fluctuate.

[0113] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of nitrile rubber (NBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0114] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one of vapor-grown carbon fiber (VGCF), superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0115] In some embodiments, the positive electrode sheet can be prepared by uniformly mixing the components used to prepare the positive electrode sheet, such as the positive electrode active material, solid electrolyte material, and conductive agent, to obtain a composite positive electrode powder. A binder, nitrile rubber, is added to the composite positive electrode powder, and the mixture is rolled to obtain a positive electrode sheet of a certain thickness.

[0116] Electrolyte membrane

[0117] In some embodiments, the secondary battery cell includes a gel electrolyte membrane, a semi-solid electrolyte membrane, or a solid electrolyte membrane.

[0118] In some embodiments, the gel electrolyte membrane includes at least one of a composite gel polymer electrolyte membrane and a porous colloidal polymer electrolyte membrane.

[0119] In some embodiments, the semi-solid electrolyte membrane includes at least one of a gel polymer electrolyte membrane, a polymer electrolyte membrane, and an aerogel electrolyte membrane.

[0120] In some embodiments, the solid electrolyte membrane includes at least one of sulfide solid electrolyte membrane, oxide solid electrolyte membrane, and halide solid electrolyte membrane.

[0121] In some embodiments, the solid electrolyte membrane can be obtained by mixing one or more of the following: a binary compound such as Li6PS5Cl, Li2S-GeS2, Li2S-P2S5, Li2S-SiS2, and a ternary compound such as Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.) with a binder such as PTFE, polyvinylidene fluoride, ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin, and then rolling it out.

[0122] In some implementations, the positive electrode, negative electrode, and electrolyte membrane can be fabricated into an electrode assembly using a winding or stacking process.

[0123] In some embodiments, the secondary battery cell may include an outer packaging. This outer packaging can be used to encapsulate the aforementioned electrode assembly and electrolyte.

[0124] In some embodiments, the outer packaging of the secondary battery cell can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging of the secondary battery cell can also be a soft pack, such as a pouch. The soft pack can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0125] This disclosure does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 shows a square-structured secondary battery cell 5 as an example.

[0126] In some embodiments, referring to FIG3, the outer packaging may include a housing 51 and a top cover assembly 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can cover the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery cell 5 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0127] In some implementations, the secondary battery cells can be assembled into a battery module. The number of secondary battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0128] Figure 4 shows a battery module 4 as an example. Referring to Figure 4, in the battery module 4, multiple secondary battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary battery cells 5 can be fixed in place using fasteners.

[0129] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple secondary battery cells 5 are received.

[0130] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0131] Figures 5 and 6 show a battery pack 1 as an example. Referring to Figures 5 and 6, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper box 2 and a lower box 3, with the upper box 2 covering the lower box 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0132] Electrical appliances

[0133] A second aspect of this disclosure provides an electrical device that includes a secondary battery cell provided in the first aspect of this disclosure.

[0134] Secondary battery cells and the battery modules they are assembled into can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices can include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0135] As an electrical device, you can choose individual battery cells, battery modules, or battery packs according to your usage requirements.

[0136] Figure 7 shows an example of an electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery cells in this device, a battery pack or battery module can be used.

[0137] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0138] Example

[0139] The following describes embodiments of this disclosure. The embodiments described below are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0140] Example 1

[0141] Preparation of secondary batteries:

[0142] 1) Preparation of negative electrode sheet

[0143] a. Preparation of the first negative electrode slurry: Graphite material, sulfide electrolyte material Li6PS5Cl, and binder nitrile rubber (NBR) were uniformly mixed at a weight ratio of 88:10:2 and dissolved in xylene to obtain a first negative electrode slurry with a solid content of 60%. Preparation of the second negative electrode slurry: Graphite material, sulfide electrolyte Li6PS5Cl, and binder nitrile rubber (NBR) were uniformly mixed at a weight ratio of 68:30:2 and dissolved in xylene to obtain a second negative electrode slurry with a solid content of 60%. The graphite material had an OI value of 3.58, a Dv50 of 12 μm, a (Dv90-Dv10) / Dv50 ratio of 1, and a specific surface area of ​​1.1 m². 2 / g, with a graphitization degree of 94%; the volume distribution particle size Dv50 of the sulfide electrolyte material Li6PS5Cl is 700nm.

[0144] b. A second negative electrode slurry is coated onto one surface of a copper foil, dried, and cold-pressed to obtain a second region. Then, a first negative electrode slurry is coated onto the second region, dried, and cold-pressed to obtain a negative electrode sheet. The coating thickness of the first region is 75 μm, and the coating thickness of the second region is 175 μm. After cold pressing, the cold-pressed thickness of the first region is 40 μm, and the cold-pressed thickness of the second region is 140 μm. The mass ratio of graphite material to solid electrolyte material in the first region is 8.8:1, and the mass ratio of graphite material to solid electrolyte material in the second region is 6.8:3.

[0145] 2) Assembly of button cells

[0146] In an argon-filled glove box, firstly, 100 mg of sulfide electrolyte Li6PS5Cl was placed in a solid mold with a diameter of 10 mm and cold-pressed for 1 min under a pressure of 1 t to obtain a solid electrolyte membrane. Then, a negative electrode was placed on one side of the solid electrolyte membrane and cold-pressed for 3 min under a pressure of 4 t to compact it. Next, a lithium sheet with a copper current collector was placed on the other side of the solid electrolyte membrane as a counter electrode and cold-pressed for 5 min under a pressure of 4 t to prepare a coin cell. The lithium sheet in the counter electrode faces the solid electrolyte membrane, the thickness of the lithium sheet is 50 μm, and the thickness of the copper current collector is 6 μm.

[0147] Button cell battery performance test

[0148] (1) Ratio Performance Test

[0149] At 25°C, the coin cell prepared above was charged to 2V at a constant current rate of 0.1C; after standing for 30 minutes, the coin cell was discharged to 0.01V at a constant current rate of 2C. The discharge capacity at this time was recorded, which is the discharge capacity at 2C. The nominal capacity at 1C is 372mAh / g. The results are recorded in Table 2 below.

[0150] (2) Cyclic performance test

[0151] The coin cell prepared above was discharged at a constant current of 0.1C to 0.01V, then charged at a constant current to 2V, left to stand for 5 minutes, and then discharged at a constant current of 0.33C to 0.01V to obtain the first discharge capacity C1. The above process was repeated 100 times to obtain the discharge capacity C2 of the 100th cycle.

[0152] The capacity retention rate after 100 cycles = C2 / C1*100%, and the test results are recorded in Table 2 below.

[0153] Examples 2-6

[0154] The secondary battery cells were prepared using the same method as in Example 1, except that the parameters of the negative electrode were adjusted, as detailed in Table 1.

[0155] Comparative Example 1

[0156] The secondary battery cells were prepared using the same method as in Example 1, except that the weight ratio of graphite material, sulfide electrolyte Li6PS5Cl, and binder nitrile rubber NBR in the second negative electrode slurry was 88:10:2.

[0157] Comparative Example 2

[0158] The secondary battery cells were prepared using the same method as in Example 1, except that the weight ratio of graphite material, sulfide electrolyte Li6PS5Cl, and binder nitrile rubber NBR in the first negative electrode slurry was 68:30:2; and the weight ratio of graphite material, sulfide electrolyte Li6PS5Cl, and binder nitrile rubber NBR in the second negative electrode slurry was 88:10:2.

[0159] Table 1 below shows the relevant parameters of the negative electrode sheets in Examples 1 to 6 and Comparative Examples 1 to 2. Table 2 below shows the performance test results of the coin cells prepared in Examples 1 to 6 and Comparative Examples 1 to 2.

[0160] Table 1

[0161] Table 2

[0162] As can be seen from Tables 1 and 2, compared with Comparative Example 1 (the content of solid electrolyte material in the first region is equal to the content of electrolyte material in the second region) and Comparative Example 2 (the content of solid electrolyte material in the first region is greater than the content of electrolyte material in the second region), in Examples 1-6, by controlling the content of solid electrolyte material in the first region to be less than the content of electrolyte material in the second region, the rate performance and cycle performance of the secondary battery are significantly improved.

[0163] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same essential structure and achieving the same effect as the technical concept within the scope of this disclosure are included in the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included in the scope of this disclosure without departing from the spirit of this disclosure.

Claims

A secondary battery cell includes a negative electrode sheet, the negative electrode sheet including a negative current collector and a negative electrode film layer located on at least one side of the negative current collector; in, The negative electrode film layer includes a solid electrolyte material and a graphite material; the negative electrode film layer includes a first region and a second region, wherein the second region is located between the first region and the negative electrode current collector; The content of the solid electrolyte material in the first region is less than the content of the solid electrolyte material in the second region. According to claim 1, the secondary battery cell, wherein, Based on the total mass of the negative electrode film, the mass percentage of the solid electrolyte material is 20% to 50%; and / or, Based on the total mass of the first region, the mass percentage of the solid electrolyte material is 10% to 50%; and / or, Based on the total mass of the second region, the solid electrolyte material accounts for 30% to 50% of the total mass; and / or, The ratio of the content of the solid electrolyte material in the first region to the content of the solid electrolyte material in the second region is greater than or equal to 0.2 and less than 1. According to claim 1 or 2, the secondary battery cell, wherein, The solid electrolyte material includes one or more of the following: sulfide solid electrolyte material, oxide solid electrolyte material, halide solid electrolyte material, and polymer solid electrolyte material. The secondary battery cell according to any one of claims 1 to 3, wherein, The solid electrolyte material includes Li d MX d+3 The material includes 1≤d≤6, M including one or more of Al, Ga, In, Y, Zr, Nb, Sc, Ti, Mn, and La, and X including one or more of halogens, S, O, and P. The secondary battery cell according to any one of claims 1 to 4, wherein, The volumetric particle size distribution Dv50 of the solid electrolyte material is 500 nm to 5 μm. The secondary battery cell according to any one of claims 1 to 5 is characterized in that, The OI value of the graphite material is 1 to 6. The secondary battery cell according to any one of claims 1 to 6, wherein, The mass ratio of the graphite material to the solid electrolyte material in the first region is greater than the mass ratio of the graphite material to the solid electrolyte material in the second region. The secondary battery cell according to any one of claims 1 to 7, wherein, The mass ratio of the graphite material to the solid electrolyte material in the first region is (7:3) to (9:1); and / or, The mass ratio of the graphite material to the solid electrolyte material in the second region is (5:5) to (7:3). The secondary battery cell according to any one of claims 1 to 8, wherein, The thickness of the negative electrode film layer on one side is 70 μm to 250 μm. The secondary battery cell according to any one of claims 1 to 9, wherein, The thickness ratio of the first region to the second region is (1:1) to (1:3). The secondary battery cell according to any one of claims 1 to 10, wherein, The porosity of the negative electrode film is 20% to 40%. The secondary battery cell according to any one of claims 1 to 11, wherein, The porosity of the first region is greater than that of the second region. The secondary battery cell according to any one of claims 1 to 12, wherein, The graphite material satisfies at least one of the following conditions (1) to (7): (1) The volumetric particle size distribution Dv50 of the graphite material is 1μm to 20μm; (2) The volumetric particle size distribution (Dv90-Dv10) / Dv50 of the graphite material is 1 to 3; (3) The specific surface area of ​​the graphite material is 0.5 m². 2 / g~5m 2 / g; (4) The graphitization degree of the graphite material is 91% to 96%; (5) At least a portion of the surface of the graphite material has a carbon coating layer; (6) The graphite material includes secondary particles; (7) The graphite material includes one or more of artificial graphite and natural graphite. The secondary battery cell according to any one of claims 1 to 13, wherein, The secondary battery cell also includes a positive electrode and an electrolyte membrane; The electrolyte membrane is located between the positive electrode and the negative electrode. An electrical device comprising a secondary battery cell as described in any one of claims 1 to 14.

Images