Electrochemical devices and electronic devices

Abstract

Embodiments of the present application provide an electrochemical device and an electronic device. The electrochemical device includes a positive electrode tab, a negative electrode tab, and a separator film disposed between the positive electrode tab and the negative electrode tab. The positive electrode tab includes a positive electrode current collector and a plurality of positive electrode film segments spaced apart on the positive electrode current collector, the positive electrode current collector and the plurality of positive electrode film segments forming a positive electrode tab in a comb shape. The negative electrode tab includes a negative electrode current collector and a plurality of negative electrode film segments spaced apart on the negative electrode current collector, the negative electrode current collector and the plurality of negative electrode film segments forming a negative electrode tab in a comb shape. The positive electrode film segments and the negative electrode film segments are interleaved with each other. The present application achieves a balance between the energy density and the fast charging performance of the electrochemical device.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage, specifically to electrochemical devices and electronic devices. Background Technology

[0002] With the development of electrochemical energy storage technology, increasingly higher demands are being placed on the energy density and fast-charging performance of electrochemical devices (e.g., lithium-ion batteries). Currently, the main method to improve the energy density of electrochemical devices is by increasing the thickness of the electrodes. However, increasing the electrode thickness increases the transport resistance of liquid-phase lithium ions in the thickness direction, significantly deteriorating the kinetic performance. Therefore, further improvements in this area are desired. Summary of the Invention

[0003] This application provides an electrochemical device comprising a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. The positive electrode includes a positive current collector and a plurality of positive electrode film segments spaced apart on the positive current collector, forming a comb-shaped positive electrode. The negative electrode includes a negative current collector and a plurality of negative electrode film segments spaced apart on the negative current collector, forming a comb-shaped negative electrode. The positive and negative electrode film segments are interleaved. By interleaving the positive and negative electrode film segments, the lithium-ion transport that was originally in the thickness direction of the positive / negative electrode is transferred, achieving lateral lithium-ion transport. Meanwhile, electron transport mainly occurs in the thickness direction of the positive / negative electrode, thereby significantly increasing the thickness of the positive / negative electrode. This allows for a balance between the energy density and fast-charging performance of the electrochemical device, meaning that excellent fast-charging performance can still be achieved even with increased thickness of the positive / negative electrode.

[0004] In some embodiments, the positive and negative electrode film segments are nested together to better achieve lateral lithium-ion transport. In some embodiments, the thickness of the positive electrode film segment is 30 μm to 145 μm. Since lithium ions are transported laterally at this thickness, if the positive electrode film segment is too thin, its formation becomes more difficult and it is not conducive to fully utilizing the high energy density; if the thickness is too large, it is not conducive to fully utilizing the fast-charging performance of the electrochemical device, i.e., the lithium plating window is smaller. In some embodiments, the thickness of the negative electrode film segment is 50 μm to 200 μm. Since lithium ions are transported laterally at this thickness, if the negative electrode film segment is too thin, its formation becomes more difficult and it is not conducive to fully utilizing the high energy density; if the thickness is too large, it is not conducive to fully utilizing the fast-charging performance of the electrochemical device, i.e., the lithium plating window is smaller. In some embodiments, the thickness of the positive electrode film segment is 30 μm to 110 μm, at which point better fast-charging performance can be obtained. In some embodiments, the thickness of the negative electrode film segment is 50 μm to 165 μm, at which point better fast charging performance can be obtained.

[0005] In some embodiments, the spacing between the positive electrode film segment and the adjacent negative electrode film segment is 2.5 μm to 15 μm. If this spacing is too small, it limits the thickness of the separator, which is detrimental to the electrical insulation between the positive and negative electrode plates; if the spacing is too large, it affects the overall energy density of the electrochemical device. In some embodiments, the height of the positive electrode film segment is 500 μm to 2000 μm, and the height of the negative electrode film segment is 500 μm to 2000 μm, which can significantly improve the energy density of the electrochemical device while still achieving excellent fast-charging performance.

[0006] In some embodiments, the separator comprises at least one of a polymer, an oxide, or a sulfide. In some embodiments, the polymer comprises at least one of a polyethylene oxide polymer, a polycarbonate-based polymer, or a polysiloxane-based polymer; the oxide comprises at least one of a perovskite oxide or AM2(PO4)3, wherein A is selected from one or more of Li, Na, and K; M is selected from one or more of Ge, Zr, and Ti; and the sulfide comprises Li2S-P2S5 or Li 10 GeP2S 12 At least one of the following. In some embodiments, the ratio H1 / T1 of the height H1 to the thickness T1 of the positive electrode film segment in the plurality of positive electrode film segments is 5 to 58, which is beneficial for achieving higher energy density and better fast charging performance. In some embodiments, the ratio H2 / T2 of the height H2 to the thickness T2 of the negative electrode film segment in the plurality of negative electrode film segments is 3 to 34, which is beneficial for achieving higher energy density and better fast charging performance.

[0007] Embodiments of this application also provide an electronic device, including the electrochemical device described above.

[0008] This application employs comb-shaped positive and negative electrode sheets with alternating positive and negative electrode film segments. This transfers lithium-ion transport, which was originally located in the thickness direction of the electrode sheets, to achieve lateral lithium-ion transport. Meanwhile, electron transport mainly occurs in the thickness direction of the electrode sheets. This allows for a significant increase in electrode thickness, achieving a balance between energy density and fast-charging performance in the electrochemical device. In other words, excellent fast-charging performance can still be achieved even with increased thickness of the positive / negative electrode sheets. Attached Figure Description

[0009] Figure 1 A cross-sectional view along the length of a portion of the electrode assembly of an electrochemical device according to some embodiments is shown.

[0010] Figure 2 A cross-sectional view along the length of a portion of the electrode assembly of an electrochemical device according to some embodiments is shown. Detailed Implementation

[0011] The following embodiments are intended to enable those skilled in the art to fully understand this application, but do not limit this application in any way.

[0012] Figure 1 A cross-sectional view along the length of a portion of an electrode assembly of an electrochemical device according to some embodiments is shown. Some embodiments of this application provide an electrochemical device including an electrode assembly. In some embodiments, the electrode assembly includes a positive electrode, a negative electrode, and a separator 12 disposed between the positive and negative electrode. In some embodiments, such as Figure 1 As shown, the positive electrode includes a positive current collector 101 and a plurality of positive electrode film segments 102 spaced apart on the positive current collector 101, forming a comb-shaped positive electrode. In some embodiments, the negative electrode includes a negative current collector 111 and a plurality of negative electrode film segments 112 spaced apart on the negative current collector 111, forming a comb-shaped negative electrode.

[0013] In some embodiments, such as Figure 1As shown, the positive electrode film segment 102 and the negative electrode film segment 112 are interleaved. The positive electrode film segment 102 and the negative electrode film segment 112 are separated by a separator 12. In some embodiments, the positive electrode sheet can be formed by the following steps: forming a positive electrode film or a positive electrode active material layer on the positive electrode current collector 101, and then forming the positive electrode active material layer into multiple film segments 102 by a suitable method such as etching or laser cutting. It should be understood that the negative electrode sheet can be formed by the same method steps as the positive electrode sheet.

[0014] By interleaving the positive electrode film segment 102 and the negative electrode film segment 112, the lithium-ion transport that was originally in the thickness direction of the positive / negative electrode is transferred, thereby achieving lateral lithium-ion transport. Figure 1 The horizontal direction of the positive / negative electrode sheet is the main direction of electron transport, while the thickness direction of the positive / negative electrode sheet is the main direction of electron transport. This allows for a significant increase in the thickness of the positive / negative electrode sheet, achieving a balance between energy density and fast charging performance of the electrochemical device. In other words, even with an increase in the thickness of the positive / negative electrode sheet, excellent fast charging performance can still be achieved.

[0015] In some embodiments, the positive electrode film segment 102 and the negative electrode film segment 112 are nested together to better achieve lateral transport of lithium ions. Nesting means that, except for the outermost positive electrode film segment 102 or negative electrode film segment 112, the remaining positive electrode film segments 102 are embedded between two adjacent negative electrode film segments 112, and the negative electrode film segments 112 are embedded between two adjacent positive electrode film segments 102.

[0016] In some embodiments, the thickness T1 of the positive electrode film segment 102 (along...) Figure 1 The thickness (in the horizontal direction) is 30 μm to 145 μm. Since lithium ions are transported laterally at this thickness, if the thickness T1 of the positive electrode film segment 102 is too small, it becomes more difficult to form the positive electrode film segment 102, and it is not conducive to fully utilizing the high energy density; if the thickness T1 of the positive electrode film segment 102 is too large, it is not conducive to fully utilizing the fast-charging performance of the electrochemical device, i.e., the lithium plating window is smaller. In some embodiments, the thickness T1 of the positive electrode film segment 102 is 30 μm to 110 μm. At this thickness, better fast-charging performance can be obtained.

[0017] In some embodiments, the thickness T2 of the negative electrode film segment 112 (along...) Figure 1The thickness (in the horizontal direction) is 50 μm to 200 μm. Since lithium ions are transported in the lateral direction at this point, if the thickness T2 of the negative electrode film segment 112 is too small, it becomes more difficult to form the negative electrode film segment 112, and it is not conducive to fully utilizing the high energy density; if the thickness T2 of the negative electrode film segment 112 is too large, it is not conducive to fully utilizing the fast-charging performance of the electrochemical device, i.e., the lithium plating window is smaller. In some embodiments, the thickness T2 of the negative electrode film segment 112 is 50 μm to 165 μm. At this thickness, better fast-charging performance can be obtained.

[0018] In some embodiments, the spacing d between the positive electrode film segment 102 and the adjacent negative electrode film segment 112 is 2.5 μm to 15 μm. If the spacing d is too small, it limits the thickness of the separator 12, which is detrimental to the electrical insulation between the positive and negative electrode plates; if the spacing d is too large, it affects the overall energy density of the electrochemical device. In some embodiments, typically, the distance between adjacent positive electrode film segments 102 is the thickness T2 of the negative electrode film segment 112 plus twice the spacing d. In some embodiments, typically, the distance between adjacent negative electrode film segments 112 is the thickness T1 of the positive electrode film segment 102 plus twice the spacing d.

[0019] In some embodiments, the height H1 of the positive electrode film segment 102 is 500 μm to 2000 μm, and the height H2 of the negative electrode film segment 112 is 500 μm to 2000 μm. It should be understood that the height H1 of the positive electrode film segment 102 corresponds to the thickness of the positive electrode active material layer during formation, and the height H2 of the negative electrode film segment 112 corresponds to the thickness of the negative electrode active material layer during formation. The height H1 of the positive electrode film segment 102 is much larger than the thickness of existing positive electrode active material layers, and the height H2 of the negative electrode film segment 112 is much larger than the thickness of existing negative electrode active material layers, which are typically around 100 μm thick. This significantly increases the energy density of the electrochemical device. Furthermore, since lithium ions are transported in the lateral direction, excellent fast-charging performance can still be achieved even with larger heights H1 and / or H2. If the height H1 of the positive electrode film segment 102 and / or the height H2 of the negative electrode film segment 112 are too small, it will not be conducive to the full utilization of high energy density; if the height H1 of the positive electrode film segment 102 and / or the height H2 of the negative electrode film segment 112 are too large, the structural stability of the formed electrode assembly will be poor, and it will not be conducive to the improvement of fast charging performance.

[0020] In some embodiments, the ratio H1 / T1 of the height H1 to the thickness T1 of the positive electrode film segment in the plurality of positive electrode film segments 102 is 5 to 58. This is beneficial for achieving higher energy density and better fast charging performance. In some embodiments, the ratio H2 / T2 of the height H2 to the thickness T2 of the negative electrode film segment in the plurality of negative electrode film segments 112 is 3 to 34. This is beneficial for achieving higher energy density and better fast charging performance.

[0021] In some embodiments, the positive current collector 101 may be made of aluminum foil, or other positive current collectors commonly used in the art may be used. In some embodiments, the thickness of the positive current collector 101 may be from 1 μm to 50 μm.

[0022] In some embodiments, the positive electrode film segment 102 may include a positive electrode active material, a conductive agent, and a binder. In some embodiments, the positive electrode active material may include at least one of lithium cobalt oxide, lithium iron phosphate, lithium aluminate, lithium manganese oxide, or lithium nickel cobalt manganese oxide. In some embodiments, the conductive agent in the positive electrode film segment 102 may include at least one of conductive carbon black, sheet graphite, graphene, or carbon nanotubes. In some embodiments, the binder in the positive electrode film segment 102 may include at least one of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. In some embodiments, the mass ratio of the positive electrode active material, the conductive agent, and the binder is (80-99):(0.1-10):(0.1-10), but this is only an example, and any other suitable mass ratio may be used.

[0023] In some embodiments, the negative electrode current collector 111 may be at least one of copper foil, nickel foil, or carbon-based current collector. In some embodiments, the negative electrode film segment 112 may include a negative electrode active material, a conductive agent, and a binder. In some embodiments, the negative electrode active material may include at least one of graphite or silicon-based material. In some embodiments, the silicon-based material includes at least one of silicon, silicon-oxygen material, silicon-carbon material, or silicon-oxygen-carbon material. In some embodiments, the conductive agent in the negative electrode film segment 112 may include at least one of conductive carbon black, Ketjen black, sheet graphite, graphene, carbon nanotubes, or carbon fibers. In some embodiments, the binder in the negative electrode film segment 112 may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene. In some embodiments, the mass ratio of the negative electrode active material, conductive agent, and binder in the negative electrode film segment 112 may be (78 to 98.5):(0.1 to 10):(0.1 to 10). It should be understood that the above are merely examples, and any other suitable materials and mass ratios can be used.

[0024] In some embodiments, the separator 12 comprises at least one of a polymer, an oxide, or a sulfide. In some embodiments, the polymer comprises at least one of a polyethylene oxide polymer, a polycarbonate-based polymer, or a polysiloxane-based polymer. In some embodiments, the oxide comprises at least one of a perovskite oxide or AM2(PO4)3, wherein A is selected from one or more of Li, Na, and K, and M is selected from one or more of Ge, Zr, and Ti. In some embodiments, the sulfide comprises Li2S-P2S5 or Li 10 GeP2S 12 At least one of the following. In some embodiments, the isolation membrane 12 can be formed by deposition. In some embodiments, the thickness of the isolation membrane 12 is 2.5 μm to 15 μm.

[0025] Figure 2 A cross-sectional view along the length of a portion of the electrode assembly in an deployed state of an electrochemical device according to some embodiments is shown. Figure 2 The electrode assembly is shown as having a two-layer structure. It should be understood that the electrode assembly can be formed into a structure with more layers.

[0026] In some embodiments, the electrochemical device includes a lithium-ion battery, but this application is not limited thereto. In some embodiments, the electrochemical device further includes an electrolyte comprising at least one of a fluoroether, a fluoroethylene carbonate, or an ether nitrile. In some embodiments, the electrolyte further includes a lithium salt comprising lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, wherein the concentration of the lithium salt is from 1 mol / L to 2 mol / L, and the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is from 0.06 to 5. In some embodiments, the electrolyte may also include a non-aqueous solvent. The non-aqueous solvent may be a carbonate compound, a carboxylic acid ester compound, an ether compound, other organic solvents, or a combination thereof.

[0027] Carbonate compounds can be chain carbonate compounds, cyclic carbonate compounds, fluorocarbonate compounds, or combinations thereof.

[0028] Examples of chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), and combinations thereof. Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), vinyl ethylene carbonate (VEC), or combinations thereof. Examples of fluorinated carbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, or combinations thereof.

[0029] Examples of carboxylic acid ester compounds are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid lactone, valerate lactone, mevalonic acid lactone, caprolactone, methyl formate, or combinations thereof.

[0030] Examples of ether compounds are dibutyl ether, tetraethylene dimethyl ether, diethylene dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, or combinations thereof.

[0031] Examples of other organic solvents include dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters or combinations thereof.

[0032] Embodiments of this application also provide electronic devices including the electrochemical devices described above. The electronic devices in the embodiments of this application are not particularly limited and can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, drones, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0033] The following specific embodiments are provided to better illustrate this application, wherein a lithium-ion battery is used as an example.

[0034] Example 1

[0035] Preparation of the negative electrode sheet: Artificial graphite (negative electrode active material), conductive carbon black, and styrene-butadiene rubber (binder) were dissolved in deionized water at a weight ratio of 96.5:1:2.5 to form a negative electrode slurry. A 10 μm thick copper foil was used as the negative electrode current collector. The negative electrode slurry was coated onto the current collector to a thickness of 500 μm (corresponding to the height of the negative electrode film segment). After drying, cold pressing, and laser cutting, the negative electrode sheet was obtained. The thickness of the negative electrode film segment was 50 μm, and the spacing between the negative electrode film segments was 40 μm.

[0036] Positive electrode preparation: Lithium cobalt oxide (positive electrode active material), conductive carbon black (conductive agent), and polyvinylidene fluoride (PVDF) (binder) were dissolved in an N-methylpyrrolidone (NMP) solution at a weight ratio of 96.2:1.5:2.3 to form a positive electrode slurry. Aluminum foil was used as the positive electrode current collector, and the positive electrode slurry was coated onto the current collector to a thickness of 500 μm (corresponding to the height of the positive electrode film segment). After drying, cold pressing, and laser cutting, the positive electrode sheet was obtained. The thickness of the positive electrode film segment was 30 μm, and the spacing between the positive electrode film segments was 60 μm.

[0037] Preparation of the separating membrane: Preparation of the oxidized solid electrolyte Li 0.7 Sr 0.2 La 0.3 TiO3 is coated onto the positive electrode to form a separator film with a thickness of 2 μm.

[0038] Preparation of electrolyte: Under an environment with a water content of less than 10 ppm, lithium hexafluorophosphate was mixed with a non-aqueous organic solvent (ethylene carbonate (EC): propylene carbonate (PC): polypropylene (PP): diethyl carbonate (DEC) = 1:1:1:1, mass percentage) to prepare an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0039] Lithium-ion battery fabrication: Positive and negative electrode sheets with deposited separators are nested and assembled to obtain an electrode assembly. The separator acts as a barrier between the positive and negative electrode sheets. The electrode assembly is placed in an outer aluminum-plastic film package, and after dehydration at 80°C, the electrolyte is injected and the assembly is sealed. Following formation, degassing, and shaping processes, a lithium-ion battery is obtained.

[0040] The parameters for Examples 2 to 24 are the same as those for Example 1, except for the differences shown in Table 1.

[0041] In addition, the relevant parameters are measured using the following method in this application.

[0042] The test methods for the thickness T1 of the positive electrode film segment and the thickness T2 of the negative electrode film segment; the height H1 of the positive electrode film segment and the height H2 of the negative electrode film segment; and the spacing d between the positive and negative electrode film segments:

[0043] Take a lithium-ion battery and discharge it to 3.0V at 0.2C. Disassemble the lithium-ion battery and remove the positive and negative electrode plates separately. Use an optical microscope to photograph the removed positive and negative electrode plates and measure their corresponding dimensions. Considering the testing accuracy, it is necessary to perform tests at 10 different locations for the same characteristic position and take the average value as the dimension of that characteristic position.

[0044] Lithium plating window test:

[0045] First, the battery is fully discharged. Then, a specific temperature is set (e.g., 25°C). Depending on the battery design, it is charged at different rates, such as 1C, 1.1C, 1.2C, etc., using a constant current + constant voltage method. This means charging to the rated voltage of the lithium-ion battery at the specified rate. Afterward, constant voltage charging is performed until 0.05C is reached, then charging is stopped. Finally, a full discharge at 0.2C is performed. This charge-discharge cycle is repeated 10 times. Finally, the fully charged lithium-ion battery is disassembled to observe whether lithium plating occurs on the negative electrode. The maximum current at which no lithium plating occurs (no white or gray lithium is present on the surface of the negative electrode) is defined as the maximum non-lithiation rate of the lithium-ion battery, also known as the lithium plating window.

[0046] Energy density testing:

[0047] The lithium-ion battery was charged at a constant current rate of 0.2C to 4.45V, and then charged at a constant voltage rate to 0.025C to complete the full charge. Next, it was discharged at a constant current rate of 0.2C until the voltage dropped to 3.0V. The total capacity discharged during the discharge process was recorded as C. The actual thickness H of the lithium-ion battery was measured, and the actual volume V of the lithium-ion battery was calculated. The energy density was calculated as C / V.

[0048] Table 1 shows the parameters and evaluation results for Examples 1 to 24, respectively.

[0049] Table 1

[0050]

[0051] Comparing Examples 1 to 8, it can be seen that as the thickness of the positive electrode film segment and the thickness of the negative electrode film segment increase, the energy density of the lithium-ion battery tends to increase, while the lithium plating window tends to decrease.

[0052] Comparing Examples 8 to 11, it can be seen that as the thickness of the positive electrode film segment decreases and the thickness of the negative electrode film segment increases, the energy density of the lithium-ion battery tends to increase, while the lithium plating window tends to decrease.

[0053] Comparing Examples 10 and 12 reveals that when the thickness of the positive electrode film segment increases while the thickness of the negative electrode film segment remains constant, the energy density of the lithium-ion battery decreases while the lithium plating window remains essentially unchanged. Furthermore, when the thickness of the positive electrode film segment exceeds 145 μm or the thickness of the negative electrode film segment exceeds 200 μm, either the energy density of the lithium-ion battery decreases or the lithium plating window decreases.

[0054] Comparing Examples 2 and 13 to 17, it can be seen that as the spacing between positive electrode film segments and the spacing between negative electrode film segments increase, or as the distance between positive and negative electrode film segments increases, the energy density of the lithium-ion battery tends to decrease, and the lithium plating window tends to decrease. When the distance between positive and negative electrode film segments is greater than 15 μm, the energy density of the lithium-ion battery decreases significantly, and the lithium plating window also decreases significantly.

[0055] By comparing Examples 2 and Examples 18 to 24, it can be seen that as the height of the positive electrode film segment and the height of the negative electrode film segment increase, the energy density of the lithium-ion battery tends to increase, while the lithium plating window tends to decrease.

[0056] Furthermore, by comparing Examples 1 to 24, it can be seen that when the ratio of the height to the thickness of the positive electrode film segment is less than 5, or the ratio of the height to the thickness of the negative electrode film segment is less than 3, the lithium plating window of the lithium-ion battery is small; in addition, when the ratio of the height to the thickness of the positive electrode film segment is greater than 58, or the ratio of the height to the thickness of the negative electrode film segment is greater than 34, the lithium plating window of the lithium-ion battery also becomes significantly smaller.

[0057] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by any combination of the above-described technical features or their equivalents. For example, technical solutions formed by substituting the above-described features with technical features having similar functions disclosed in this application.

Claims

1. An electrochemical device comprising: A positive electrode sheet, the positive electrode sheet comprising a positive current collector and a plurality of positive electrode film segments spaced apart on the positive current collector, the positive current collector and the plurality of positive electrode film segments forming a comb-shaped positive electrode sheet; A negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a plurality of negative electrode film segments spaced apart on the negative electrode current collector, the negative electrode current collector and the plurality of negative electrode film segments forming a comb-shaped negative electrode sheet; A separator is disposed between the positive electrode and the negative electrode. The positive electrode film segment and the negative electrode film segment are interleaved; The ratio of the height H1 to the thickness T1 of the positive electrode film segment in the plurality of positive electrode film segments, H1 / T1, is 5 to 58; the ratio of the height H2 to the thickness T2 of the negative electrode film segment in the plurality of negative electrode film segments, H2 / T2, is 3 to 34.

2. The electrochemical device according to claim 1, wherein, The positive electrode film segment and the negative electrode film segment are nested together.

3. The electrochemical device according to claim 1, wherein, The thickness T1 of the positive electrode film segment is 30 μm to 145 μm, and the thickness T2 of the negative electrode film segment is 50 μm to 200 μm.

4. The electrochemical device according to claim 1, wherein, The thickness T1 of the positive electrode film segment is 30 μm to 110 μm, and the thickness T2 of the negative electrode film segment is 50 μm to 165 μm.

5. The electrochemical device according to claim 1, wherein, The spacing d between the positive electrode film segment and the adjacent negative electrode film segment is 2.5 μm to 15 μm.

6. The electrochemical device according to claim 1, wherein, The height H1 of the positive electrode film segment is 500 μm to 2000 μm, and the height H2 of the negative electrode film segment is 500 μm to 2000 μm.

7. The electrochemical device according to claim 1, wherein, The separator membrane comprises at least one of a polymer, an oxide, or a sulfide.

8. The electrochemical device according to claim 7, wherein, The polymer comprises at least one of a polyoxyethylene polymer, a polycarbonate-based polymer, or a polysiloxane-based polymer; the oxide comprises at least one of a perovskite oxide or AM2(PO4)3; wherein A is selected from one or more of Li, Na, and K, and M is selected from one or more of Ge, Zr, and Ti; and the sulfide comprises Li2S-P2S5 or Li 10 GeP2S 12 At least one of them.

9. An electronic device comprising an electrochemical device according to any one of claims 1 to 8.

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