Electrochemical device and control method thereof, electronic device and storage medium

Abstract

The present application provides an electrochemical device and a control method thereof, an electronic device and a storage medium. The control method of the electrochemical device includes steps a) and b): a) when the internal resistance change rate of the electrochemical device is less than a first threshold value, charging and discharging are performed at a first voltage and a second voltage; b) when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value, the discharge cut-off voltage of the electrochemical device is increased by a first increase amount. By monitoring the change in the internal resistance change rate of the electrochemical device and controlling the electrochemical device accordingly based on the internal resistance change rate, the cycle performance of the electrochemical device is improved while maintaining the high energy density of the electrochemical device.

Description

Technical Field

[0001] The present application relates to the field of electrochemical energy storage, and in particular to an electrochemical device and a control method thereof, an electronic device and a storage medium. Background Art

[0002] With the development and progress of electrochemical devices (e.g., lithium-ion batteries), higher and higher requirements are placed on their cycle performance and energy density. At present, in terms of improving the energy density of electrochemical devices, the use of silicon-based materials in the negative electrode is the current trend. In addition to the improvement of materials, improvements in other aspects are also expected to improve the cycle performance and energy density of electrochemical devices. Summary of the invention

[0003] Some embodiments of the present application provide a control method for an electrochemical device, wherein the initial discharge cut-off voltage of the electrochemical device is a first voltage, and the initial charge cut-off voltage is a second voltage, and the control method comprises steps a) and b): a) when the internal resistance change rate of the electrochemical device is less than a first threshold value, charging and discharging are performed at the first voltage and the second voltage; b) when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value, increasing the discharge cut-off voltage of the electrochemical device by a first increase amount.

[0004] In some embodiments, when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value, increasing the discharge cut-off voltage of the electrochemical device by the first increase amount includes: c) when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value and less than or equal to the second threshold value, increasing the discharge cut-off voltage of the electrochemical device by the first increase amount, wherein the second threshold value is greater than the first threshold value; d) when the internal resistance change rate of the electrochemical device is greater than the second threshold value, performing operations related to the charge and discharge state of the electrochemical device. By adopting the control method of the present application, when using the electrochemical device, in the early stage when the internal resistance change rate is small, the high energy density characteristics of the electrochemical device can be fully utilized. In addition, during the cycle process, the internal resistance change rate state of the electrochemical device can be automatically monitored, and it is intelligently determined whether to increase the discharge cut-off voltage of the electrochemical device by the first increase amount or perform operations related to the charge and discharge state of the electrochemical device, thereby maintaining the high energy density of the electrochemical device while improving the cycle life of the electrochemical device.

[0005] In some embodiments, the electrochemical device includes a negative electrode plate, the negative electrode plate includes a negative electrode active material layer, and the negative electrode active material layer includes a silicon-based material. By adopting a silicon-based material, the energy density of the electrochemical device can be improved. 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 mass of the Si element in the negative electrode active material layer accounts for 1% to 90% of the mass of the negative electrode active material layer. If the mass of the Si element in the negative electrode active material layer accounts for too small a proportion of the mass of the negative electrode active material layer, the effect of improving the energy density of the electrochemical device is relatively limited; if the mass of the Si element in the negative electrode active material layer accounts for too large a proportion of the mass of the negative electrode active material layer, the cyclic expansion of the silicon-based material is too large and affects the cyclic performance of the electrochemical device.

[0006] In some embodiments, the first voltage ranges from 2.5V to 3.5V, and the second voltage ranges from 4.2V to 4.6V. When the first voltage is too high, it is not conducive to fully utilizing the energy density of the electrochemical device; when the first voltage is too low, it is easy to cause irreversible damage to the electrochemical device. When the second voltage is too high, it is easy to cause irreversible damage to the electrochemical device; when the second voltage is too low, it is not conducive to fully utilizing the energy density of the electrochemical device. In some embodiments, the first threshold satisfies: 1% ≤ first threshold ≤ 10%. If the first threshold is set too small, the discharge cut-off voltage will be increased when the cycle state of the electrochemical device is good, which is not conducive to fully utilizing the energy density of the electrochemical device. If the first threshold is set too large, the effect of improving the cycle life of the electrochemical device will be relatively limited. In some embodiments, the second threshold satisfies 10% < second threshold ≤ 20%. If the second threshold is set too small, operations related to the charge and discharge state of the electrochemical device will be performed when the cycle state of the electrochemical device is good. If the second threshold is set too large, the effect of improving the cycle life of the electrochemical device and improving the safety performance of the electrochemical device will be relatively limited. In some embodiments, the value range of the first boost amount is 0.03V to 0.6V. If the value of the first boost amount is too small, it may be necessary to frequently perform operations to increase the discharge cut-off voltage, or the effect of increasing the cycle life of the electrochemical device may be relatively limited. If the value of the first boost amount is too large, the discharge cut-off voltage of the electrochemical device will be too large and will not be conducive to fully utilizing the energy density of the electrochemical device. In some embodiments, performing operations related to the charge and discharge state of the electrochemical device includes at least one of steps e) to f): e) stopping the charge and discharge operation of the electrochemical device; f) sending a prompt message to stop the charge and discharge operation of the electrochemical device. When the internal resistance change rate of the electrochemical device is greater than the second threshold value, there may be an abnormality in the cycle of the electrochemical device at this time. By stopping the charge and discharge operation of the electrochemical device and / or sending a prompt message to stop the charge and discharge operation of the electrochemical device, for example, reminding the user to replace the battery, safety risks such as battery bloating can be avoided.

[0007] Another embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned control method of the electrochemical device is implemented.

[0008] Another embodiment of the present application provides a charging device, including a processor and a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions that can be executed by the processor, and when the processor executes the computer-executable instructions, the above-mentioned control method of the electrochemical device is implemented.

[0009] Another embodiment of the present application provides an electrochemical device, which includes a processor and a computer-readable storage medium, the initial discharge cut-off voltage of the electrochemical device is a first voltage, the initial charge cut-off voltage is a second voltage, the computer-readable storage medium stores computer-executable instructions that can be executed by the processor, and when the processor executes the computer-executable instructions, a control method is implemented, and the control method includes steps a) and b): a) when the internal resistance change rate of the electrochemical device is less than a first threshold value, charging and discharging are performed at the first voltage and the second voltage; b) when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value, the discharge cut-off voltage of the electrochemical device is increased by a first increase amount.

[0010] In some embodiments, when the internal resistance change rate of the electrochemical device is greater than or equal to a first threshold, increasing the discharge cut-off voltage of the electrochemical device by a first increase amount includes: c) when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold and less than or equal to a second threshold, increasing the discharge cut-off voltage of the electrochemical device by the first increase amount, wherein the second threshold is greater than the first threshold; d) when the internal resistance change rate of the electrochemical device is greater than the second threshold, performing operations related to the charge and discharge state of the electrochemical device.

[0011] In some embodiments, the electrochemical device includes a negative electrode sheet, the negative electrode sheet includes a negative electrode active material layer, and the negative electrode active material layer includes a 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 mass of the Si element in the negative electrode active material layer accounts for 1% to 90% of the mass of the negative electrode active material layer.

[0012] In some embodiments, the first voltage ranges from 2.5V to 3.5V, and the second voltage ranges from 4.2V to 4.6V. In some embodiments, the first threshold satisfies: 1% ≤ first threshold ≤ 10%, and the second threshold satisfies 10% < second threshold ≤ 20%. In some embodiments, the first boost ranges from 0.03V to 0.6V. In some embodiments, performing operations related to the charge and discharge state of the electrochemical device includes at least one of steps e) to f): e) stopping the charge and discharge operation of the electrochemical device; f) sending a prompt message to stop the charge and discharge operation of the electrochemical device.

[0013] An embodiment of the present application further provides an electronic device, comprising the above-mentioned electrochemical device.

[0014] The embodiments of the present application monitor the change in the internal resistance change rate of the electrochemical device and control the electrochemical device accordingly based on the internal resistance change rate, thereby improving the cycle performance of the electrochemical device while maintaining a high energy density of the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram showing a control method of an electrochemical device according to some embodiments of the present application is shown.

[0016] Figure 2 This is a schematic diagram of the structure of a charging device according to some embodiments of the present application.

[0017] Figure 3 A schematic diagram of the structure of the system of some embodiments of the present application. DETAILED DESCRIPTION

[0018] The following embodiments may enable those skilled in the art to more fully understand the present application, but do not limit the present application in any way.

[0019] like Figure 1 As shown, some embodiments of the present application provide a control method for an electrochemical device. In some embodiments, the initial discharge cut-off voltage of the electrochemical device is a first voltage, and the initial charge cut-off voltage is a second voltage. The initial discharge cut-off voltage of the electrochemical device refers to the voltage when the electrochemical device can no longer continue to discharge (i.e., discharge to a state of charge (SOC) of 0%), and the initial charge cut-off voltage of the electrochemical device refers to the voltage when the electrochemical device is charged to an SOC of 100%. In some embodiments, the electrochemical device includes but is not limited to lithium-ion batteries. In some embodiments, the control method of the present application includes steps a) and b).

[0020] In step a), when the internal resistance change rate of the electrochemical device is less than the first threshold value, charging and discharging are performed at the first voltage and the second voltage, that is, charging and discharging are performed at the initial charge cut-off voltage and the initial discharge cut-off voltage. In the present application, the internal resistance change rate of the electrochemical device refers to the change rate of the current internal resistance of the electrochemical device relative to the internal resistance before 100 cycles, with one charge and one discharge process as a cycle. For example, the internal resistance of the electrochemical device in an unused state is n when tested by an internal resistance meter, and the internal resistance of the electrochemical device is m when tested every 100 cycles, then the internal resistance change rate is (mn) / n. For example, the electrochemical device is taken out from an electronic device using an electrochemical device, the internal resistance of the electrochemical device is tested by an internal resistance meter, and then the electrochemical device is subjected to a discharge and charge cycle, and the internal resistance of the electrochemical device is tested by an internal resistance meter every 100 cycles (one discharge and one charge are considered as one cycle as a whole). It should be understood that this is only exemplary, and other suitable internal resistance change rate test methods may also be used. As the electrochemical device continues to cycle, the internal resistance of the electrochemical device tends to increase. When the change rate of the internal resistance of the electrochemical device within every 100 cycles is less than the first threshold value, it indicates that the cycle of the electrochemical device is within a controllable range and the charge and discharge cycle can be performed according to the initial setting conditions.

[0021] In step b), when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value, the discharge cut-off voltage of the electrochemical device is increased by a first increase amount. As the cycle of the electrochemical device proceeds, the internal resistance change rate of the electrochemical device increases to the first threshold value. At this time, by increasing the discharge cut-off voltage of the electrochemical device by the first increase amount, that is, using the full charge and shallow discharge mode, increasing the discharge cut-off voltage can reduce the charge and discharge depth of the negative electrode plate, so that the negative electrode active material is in the full charge and shallow discharge mode, thereby increasing the cycle life of the electrochemical device.

[0022] In some embodiments, when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold, increasing the discharge cut-off voltage of the electrochemical device by a first increase includes steps c) and d). In step c), when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold and less than or equal to the second threshold, the discharge cut-off voltage of the electrochemical device is increased by a first increase, wherein the second threshold is greater than the first threshold. As the cycle of the electrochemical device proceeds, the internal resistance change rate of the electrochemical device increases to above the first threshold and below the second threshold. At this time, by increasing the discharge cut-off voltage of the electrochemical device by the first increase, that is, using a full charge and shallow discharge mode, increasing the discharge cut-off voltage can reduce the charge and discharge depth of the negative electrode plate, so that the negative electrode active material is in a full charge and shallow discharge mode, thereby increasing the cycle life of the electrochemical device.

[0023] In step d), when the internal resistance change rate of the electrochemical device is greater than the second threshold value, operations related to the charge and discharge state of the electrochemical device are performed. In some embodiments, operations related to the charge and discharge state of the electrochemical device include any operations that affect the charge and discharge of the electrochemical device, including but not limited to stopping the charge and discharge operation of the electrochemical device and sending a prompt message to stop the charge and discharge operation of the electrochemical device. As the cycle of the electrochemical device proceeds, the internal resistance change rate of the electrochemical device increases above the second threshold value. At this time, it is determined that there is an abnormality in the cycle of the electrochemical device, and greater intervention is required, that is, operations related to the charge and discharge state of the electrochemical device are performed to increase the cycle life of the electrochemical device and reduce the possibility of safety accidents.

[0024] By adopting the control method of the present application, when using an electrochemical device, in the early stage when the internal resistance change rate is small, the high energy density characteristics of the electrochemical device can be fully utilized. In addition, during the cycle process, it can be determined whether to increase the discharge cut-off voltage of the electrochemical device by a first increase amount or perform operations related to the charge and discharge state of the electrochemical device according to the internal resistance change rate state of the electrochemical device, thereby maintaining the high energy density of the electrochemical device while improving the cycle life of the electrochemical device.

[0025] In some embodiments, the first voltage ranges from 2.5V to 3.5V, and the second voltage ranges from 4.2V to 4.6V. When the first voltage is too high, it is not conducive to fully utilizing the energy density of the electrochemical device; when the first voltage is too low, it is easy to cause irreversible damage to the electrochemical device. When the second voltage is too high, it is easy to cause irreversible damage to the electrochemical device; when the second voltage is too low, it is not conducive to fully utilizing the energy density of the electrochemical device.

[0026] In some embodiments, the first threshold satisfies: 1% ≤ first threshold ≤ 10%. When 1% ≤ first threshold ≤ 10%, it indicates that the internal change rate of the electrochemical device is small at this time, the cycle of the electrochemical device is within a controllable range, and the charge and discharge cycle can be performed according to the initial setting conditions. If the first threshold is set too small, the discharge cut-off voltage will be increased when the cycle state of the electrochemical device is good, which is not conducive to fully utilizing the energy density of the electrochemical device. If the first threshold is set too large, the effect of improving the cycle life of the electrochemical device will be relatively limited. In some embodiments, the first threshold can be 1%, 3%, 5%, 7%, 10% or other suitable values.

[0027] In some embodiments, the second threshold satisfies: 10%<second threshold≤20%. When the internal change rate of the electrochemical device is between the first threshold and the second threshold, the cycle life of the electrochemical device can be improved by increasing the discharge cut-off voltage of the electrochemical device by the first increase amount, that is, adopting a full charge and shallow discharge method. If the second threshold is set too small, operations related to the charge and discharge state of the electrochemical device will be performed when the cycle state of the electrochemical device is good. If the second threshold is set too large, the effect of improving the cycle life of the electrochemical device and improving the safety performance of the electrochemical device will be relatively limited. In some embodiments, the second threshold can be 11%, 13%, 15%, 17%, 20% or other suitable values.

[0028] In some embodiments, the value range of the first boost amount is 0.03V to 0.6V. If the value of the first boost amount is too small, it may be necessary to frequently perform operations to increase the discharge cut-off voltage, or the effect of increasing the cycle life of the electrochemical device may be relatively limited. If the value of the first boost amount is too large, the discharge cut-off voltage of the electrochemical device will be too large and will not be conducive to fully utilizing the energy density of the electrochemical device. In some embodiments, the value of the first boost amount may be 0.03V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V or other suitable values. In some embodiments, when the internal resistance change rate of the electrochemical device meets the corresponding conditions, the discharge cut-off voltage can be increased by the first boost amount multiple times until the discharge cut-off voltage of the electrochemical device reaches 3.9V or the internal resistance change rate of the electrochemical device is greater than the second threshold value.

[0029] In some embodiments, performing operations related to the charge and discharge state of the electrochemical device includes at least one of steps e) to f): e) stopping the charge and discharge operation of the electrochemical device; f) sending a prompt message to stop the charge and discharge operation of the electrochemical device. When the internal resistance change rate of the electrochemical device is greater than the second threshold, the cycle of the electrochemical device may be abnormal. By stopping the charge and discharge operation of the electrochemical device and / or sending a prompt message to stop the charge and discharge operation of the electrochemical device, for example, reminding the user to replace the battery, safety risks such as battery bloating can be avoided.

[0030] In some embodiments, the electrochemical device includes a negative electrode sheet, the negative electrode sheet includes a negative electrode active material layer, and the negative electrode active material layer includes a silicon-based material. By using a silicon-based material, the energy density of the electrochemical device can be improved. 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 mass of the Si element in the negative electrode active material layer accounts for 1% to 90% of the mass of the negative electrode active material layer. In some embodiments, if the mass of the Si element in the negative electrode active material layer accounts for too small a proportion of the mass of the negative electrode active material layer, the effect of improving the energy density of the electrochemical device is relatively limited; if the mass of the Si element in the negative electrode active material layer accounts for too large a proportion of the mass of the negative electrode active material layer, the cyclic expansion of the silicon-based material is too large and affects the cyclic performance of the electrochemical device. In some embodiments, the mass of the Si element in the negative electrode active material layer accounts for 5% to 50% of the mass of the negative electrode active material layer, which can not only achieve the improvement of the energy density of the electrochemical device, but also minimize the adverse effects of the cyclic expansion of the silicon-based material. Furthermore, the mass of the Si element in the negative electrode active material layer accounts for 5% to 20% of the mass of the negative electrode active material layer.

[0031] In the present application, the test method for the ratio of the mass of Si element in the negative electrode active material layer to the mass of the negative electrode active material layer can be performed by inductively coupled plasma optical emission spectrometry (ICP-OES): First, the negative electrode plate is pre-treated, and the pre-treatment method is to take the negative electrode plate in the battery cell and bake it in an oven at 400°C for 1h, and then make the negative electrode material layer fall off from the current collector to obtain the negative electrode material, weigh 0.2g of the negative electrode material, put it into a 50mL plastic volumetric flask, and dissolve it by microwave digestion. The acid used for digestion is 10mL HNO 3 +5mL HF, the resulting solution can be filtered and then tested by ICP to obtain the concentration of Si element (mg / L). The inductively coupled plasma emission spectrometer test method is a technology well known to those skilled in the art and will not be described in detail here. It should be noted that the lithium-ion battery monomer used in the test can be a lithium-ion battery after formation as an example, which is not limited here.

[0032] In some embodiments, the electrochemical device may include an electrode assembly, wherein the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0033] In some embodiments, the negative electrode sheet also includes a negative current collector. In some embodiments, the negative active material layer may be located on one or both sides of the negative current collector. In some embodiments, the negative active material layer may also include a conductive agent and a binder. In some embodiments, the conductive agent in the negative active material layer may include at least one of conductive carbon black, Ketjen black, lamellar graphite, graphene, carbon nanotubes, or carbon fibers. In some embodiments, the binder in the negative active material layer may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyvinyl pyrrolidone, 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 active material, the conductive agent, and the binder in the negative active material layer may be (78 to 98.5): (0.1 to 10): (0.1 to 10). It should be understood that the above is only an example, and any other suitable material and mass ratio may be used. In some embodiments, the negative current collector may be at least one of copper foil, nickel foil, or a carbon-based current collector.

[0034] In some embodiments, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector, and the positive active material layer may include a positive active material. In some embodiments, the positive active material includes at least one of lithium cobaltate, lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium-rich manganese-based materials, or lithium nickel cobalt aluminum oxide. In some embodiments, the positive active material layer may also include a conductive agent. In some embodiments, the conductive agent in the positive active material layer may include at least one of conductive carbon black, ketjen black, lamellar graphite, graphene, carbon nanotubes, or carbon fibers. In some embodiments, the positive active material layer may also include a binder, and the binder in the positive active material layer may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyvinyl pyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene. In some embodiments, the mass ratio of the positive electrode active material, the conductive agent, and the binder in the positive electrode active material layer may be (80 to 99): (0.1 to 10): (0.1 to 10). In some embodiments, the thickness of the positive electrode active material layer may be 10 μm to 500 μm. It should be understood that the above description is only an example, and the positive electrode active material layer may adopt any other suitable material, thickness, and mass ratio.

[0035] In some embodiments, the positive electrode current collector may be Al foil, and of course, other current collectors commonly used in the art may also be used. In some embodiments, the thickness of the positive electrode current collector may be 1 μm to 50 μm. In some embodiments, the positive electrode active material layer may be coated only on a partial area of ​​the positive electrode current collector.

[0036] In some embodiments, the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide or aramid. For example, polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene or ultra-high molecular weight polyethylene. In particular, polyethylene and polypropylene have a good effect on preventing short circuits and can improve the stability of the battery through the shutdown effect. In some embodiments, the thickness of the separator is in the range of about 3 μm to 20 μm.

[0037] In some embodiments, the surface of the isolation membrane may further include a porous layer, the porous layer is disposed on at least one surface of the isolation membrane, the porous layer includes inorganic particles and a binder, the inorganic particles are selected from alumina (Al 2 O 3 ), silicon oxide (SiO 2 ), magnesium oxide (MgO), titanium oxide (TiO 2 ), hafnium dioxide (HfO 2 ), tin oxide (SnO 2 ), cerium dioxide (CeO 2 ), nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate. In some embodiments, the pores of the isolation membrane have a diameter in the range of about 0.01 μm to 1 μm. The binder of the porous layer is selected from at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene. The porous layer on the surface of the isolation membrane can improve the heat resistance, oxidation resistance and electrolyte wetting performance of the isolation membrane, and enhance the adhesion between the isolation membrane and the pole piece.

[0038] In some embodiments, the electrochemical device includes a lithium ion battery, but the present application is not limited thereto. In some embodiments, the electrochemical device also includes an electrolyte, and the electrolyte includes at least one of a fluoroether, a fluoroethylene carbonate, or an ether nitrile. In some embodiments, the electrolyte also includes a lithium salt, and the lithium salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the concentration of the lithium salt is 1 mol / L to 2 mol / L, and the mass ratio of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate is 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 carboxylate compound, an ether compound, other organic solvents, or a combination thereof.

[0039] The carbonate compound may be a linear carbonate compound, a cyclic carbonate compound, a fluorinated carbonate compound or a combination thereof.

[0040] 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), butylene carbonate (BC), vinyl ethylene carbonate (VEC) or combinations thereof. Examples of fluorocarbonate 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.

[0041] Examples of the carboxylic acid ester compound are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, methyl formate, or a combination thereof.

[0042] Examples of the ether compound are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, or a combination thereof.

[0043] Examples of other organic solvents are dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphoric acid esters or combinations thereof.

[0044] In some embodiments of the present application, the electrode assembly of the electrochemical device is a wound electrode assembly, a stacked electrode assembly, or a folded electrode assembly. In some embodiments, the positive electrode sheet and / or the negative electrode sheet of the electrochemical device can be a multi-layer structure formed by winding or stacking, or a single-layer structure in which a single-layer positive electrode, a separator, and a single-layer negative electrode are stacked.

[0045] In some embodiments of the present application, taking a lithium-ion battery as an example, a positive electrode sheet, a separator, and a negative electrode sheet are wound or stacked in sequence to form an electrode assembly, and then encapsulated in, for example, an aluminum-plastic film, injected with an electrolyte, formed, and encapsulated to form a lithium-ion battery. Then, the prepared lithium-ion battery is subjected to a performance test.

[0046] Those skilled in the art will appreciate that the above-described method for preparing an electrochemical device (eg, a lithium-ion battery) is only an example, and other methods commonly used in the art may be used without departing from the disclosure of the present application.

[0047] Some specific embodiments and comparative examples are listed below to better illustrate the present application, wherein a lithium-ion battery is used as an example.

[0048] Comparative Example 1

[0049] Preparation of positive electrode sheet: Mix the positive electrode active materials lithium cobalt oxide, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) in a weight ratio of 97:1.4:1.6, add N-methylpyrrolidone (NMP) as a solvent, and stir evenly. The slurry (solid content of 72wt%) is evenly coated on the positive electrode current collector aluminum foil with a coating thickness of 80μm, dried at 85℃, and then cold pressed, cut, and slit, and dried under vacuum conditions at 85℃ for 4 hours to obtain the positive electrode sheet.

[0050] Preparation of negative electrode sheet: artificial graphite, binder polyacrylic acid and sodium carboxymethyl cellulose (CMC) are dissolved in deionized water in a weight ratio of 97:1.5:1.5 to form a negative electrode slurry (solid content is 40wt%). A 10μm thick copper foil is used as the negative electrode current collector, and the negative electrode slurry is coated on the negative electrode current collector with a coating thickness of 50μm, dried at 85°C, and then cold pressed, cut and slit, and dried under vacuum conditions at 120°C for 12 hours to obtain a negative electrode sheet.

[0051] Preparation of isolation film: The isolation film is 7 μm thick polyethylene (PE).

[0052] Preparation of electrolyte: In a dry argon atmosphere glove box, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed at a mass ratio of EC: PC: DEC = 1:1:1, dissolved and stirred thoroughly, and then lithium salt LiPF was added. 6 , and then mixed evenly to obtain an electrolyte solution, in which LiPF 6 The concentration is 1 mol / L.

[0053] Preparation of lithium-ion battery: stack the positive electrode sheet, separator, and negative electrode sheet in order, so that the separator is between the positive and negative electrodes to play a role of isolation, and wind them to obtain the electrode assembly. Place the electrode assembly in the outer packaging aluminum plastic film, remove moisture at 80°C, inject the above electrolyte and package it, and obtain the lithium-ion battery through the process of formation, degassing, trimming, etc.

[0054] A single cycle condition was used without change, wherein the first voltage was 3.0V and the second voltage was 4.45V.

[0055] In other embodiments and comparative examples, the content of the silicon-based material and the charge-discharge method are changed on the basis of the steps of comparative example 1. The specific changed parameters are as follows.

[0056] The test methods for various parameters of this application are described below.

[0057] 1. Battery charging cut-off voltage and battery discharging cut-off voltage test: You can use a battery voltage internal resistance tester or a multimeter to test.

[0058] 2. Internal resistance change rate test: The equipment is a battery voltage internal resistance tester. First, the internal resistance of the electrochemical device is tested in an unused state as n. The internal resistance of the electrochemical device is tested every 100 cycles as m. The internal resistance change rate is (mn) / n.

[0059] 3. Battery cycle number test: Use a cycle tester (using the Xinwei battery tester on the market) to perform constant current and constant voltage charge and discharge tests on the battery cells according to the set charge and discharge cut-off voltage. For example, the charge cut-off voltage of a single cell is 4.45V, and the discharge cut-off voltage is 3.0V. The cycle tester charges to 4.45V at 3C constant current at 25°C, and then discharges to 3.0V at 1C as one cycle, and repeatedly tests the different cycle numbers of the single cell. Cycle number test when the capacity decays to 80%: The formed battery cells are charged at 3C constant current at 25°C, and then discharged at 1C. The capacity at this time is recorded as the initial capacity. The number of cycles corresponding to the first decay of the battery capacity to 80% of the initial capacity (or less than 80% of the initial capacity) is recorded as the number of cycles when the capacity decays to 80%.

[0060] 4. Energy density test: At 25°C, the prepared lithium-ion battery is fully charged at a 3C rate and fully discharged at a 1C rate, and the discharge capacity at this time is recorded; at 25°C, the lithium-ion battery is weighed using an electronic balance; the ratio of the discharge capacity of the lithium-ion battery to the weight of the lithium-ion battery is the energy density of the lithium-ion battery.

[0061] It should be understood that the testing of lithium-ion battery voltage, internal resistance, and cycle life is a technology well known to those skilled in the art and will not be described in detail here. The testing method is not limited to the method described in this application, and other suitable testing methods may also be used.

[0062] Comparative Examples 1-6:

[0063] According to the steps of Comparative Example 1, part of the artificial graphite is replaced by the silicon-based material silicon dioxide (SiOx, 0<x<2), and the mass of the Si element is designed to account for the mass ratio of the negative electrode active material layer to 1%, 5%, 25%, 50% and 90%, respectively. The first voltage is set to 3.0V and the second voltage is set to 4.45V. It can be seen from Table 1 that the energy density of the electrochemical device increases with the increase of Si content, but the cycle life is significantly attenuated with the increase of Si content.

[0064] Table 1:

[0065]

[0066] Comparative Examples 7-13:

[0067] According to the steps of Comparative Example 1, part of the artificial graphite is replaced with silicon-based material SiC, and the mass of the Si element is designed to account for 25% of the mass of the negative electrode active material layer. By setting different first voltages, the second voltage remains unchanged at 4.45V. In the embodiment, when the first voltage is set to 2.5V, 2.8V, 3.0V, 3.2V, 3.3V, 3.4V, and 3.5V, it can be seen from Table 2 that the cycle life of the electrochemical device is significantly improved as the first voltage increases.

[0068] Table 2:

[0069]

[0070]

[0071] Comparative Examples 14-17:

[0072] According to the steps of Comparative Example 1, part of the artificial graphite is replaced with silicon-based material Si, and the mass of the Si element is designed to account for 25% of the mass of the negative electrode active material layer. By setting the first voltage to 3.0V and setting different second voltages of 4.2V, 4.3V, 4.45V, and 4.6V, the cycle life of the electrochemical device decreases as the second voltage increases, as shown in Table 3.

[0073] Table 3:

[0074]

[0075] Embodiment 1-5:

[0076] Table 5 shows the number of cycles when the discharge voltage of the electrochemical device starts to rise and the number of cycles when the discharge voltage decays to 80% when different first thresholds are set. The number of cycles when the discharge voltage starts to rise is the number of cycles corresponding to the first increase in the discharge voltage. That is, the number of cycles when the internal resistance change rate of the corresponding electrochemical device is not less than the first threshold for the first time.

[0077] According to the steps of comparative example 1, part of the artificial graphite is replaced with silicon-based material SiC, and when the mass of the Si element is designed to account for 25% of the mass of the negative electrode active material layer, the first voltage is 3.0V, the second voltage is 4.5V, and the first threshold satisfies: 1%≤first threshold≤10%. When 1%≤first threshold≤10%, it indicates that the internal change rate of the electrochemical device is small at this time, the cycle of the electrochemical device is in a controllable range, and the charge and discharge cycle can be performed according to the initial setting conditions. If the first threshold is set to a small value (such as the setting value of 1% in the embodiment), the discharge cut-off voltage will be increased when the electrochemical device is cycled 100 times (the value of the first increase in this embodiment is 0.2V), which is not conducive to fully utilizing the energy density of the electrochemical device. If the first threshold is set to a large value (such as the setting value of 10% in the embodiment), the discharge cut-off voltage will not be increased until the electrochemical device is cycled 600 times (generally, the number of cycles required for the capacity of a lithium-ion battery to decay to 80% is 800-1000 times. If the discharge cut-off voltage is not increased until 600 cycles, the cycle performance improvement effect is relatively limited), so that the cycle life improvement of the electrochemical device is relatively limited, as shown in Table 4.

[0078] Table 4:

[0079]

[0080] Embodiment 6-11:

[0081] According to the steps of comparative example 1, part of the artificial graphite is replaced with silicon-based material SiC, and the mass of the Si element is designed to account for 25% of the mass of the negative electrode active material layer. The first voltage is 3.0V, the second voltage is 4.5V, the first threshold a is set to 5%, and the value of the first increase is 0.2V. It can be seen from Example 4 that the first threshold is reached after 300 cycles, thereby increasing the discharge cut-off voltage to 3.2V. In further cycles, the second threshold is set, and the second threshold satisfies: 10% < second threshold ≤ 20%. Among them, Example 6 does not set the second threshold. When the internal resistance change rate is greater than the first threshold of 5%, the discharge cut-off voltage is increased by 0.2V until the discharge cut-off voltage reaches 4.4V. Operations related to the charge and discharge state of the electrochemical device are performed. In Examples 7-11, when the discharge cut-off voltage reaches 4.2V, the discharge voltage is stopped. When the internal change rate of the electrochemical device is between the first threshold and the second threshold, the discharge cut-off voltage of the electrochemical device is increased by the first increase, that is, the full charge and shallow discharge method is adopted, and the cycle life of the electrochemical device can be increased. If the second threshold is set too small, operations related to the charge and discharge state of the electrochemical device will be performed when the cycle state of the electrochemical device is good. If the second threshold is set too large, the effect of improving the cycle life of the electrochemical device and the safety performance of the electrochemical device will be relatively limited. In the embodiment, the second threshold can be 11%, 13%, 15%, 17%, 20%, and the results are shown in Table 5.

[0082] Table 5:

[0083]

[0084] In addition, the embodiment of the present application also provides a charging device, which includes a processor and a computer-readable storage medium. The computer-readable storage medium stores computer-executable instructions that can be executed by the processor. When the processor executes the computer-executable instructions, the control method steps described in any of the above embodiments are implemented. In some embodiments, the processor and the computer-readable storage medium can be installed on the same carrier (e.g., a circuit board) or distributed on different carriers. For example, the processor can access the computer-executable instructions in the remote computer-readable storage medium through various communication methods (wired or wireless). The computer-readable storage medium and the processor can be arranged on one or more of an electrochemical device, an electronic device connected to the electrochemical device, and a charging device connected to the electrochemical device. In some embodiments, the computer-readable storage medium and the processor can be arranged on the same device (e.g., an electrochemical device, or an electronic device or a charging device). In some embodiments, the computer-readable storage medium and the processor can be arranged on two different devices respectively. For example, a computer-readable storage medium can be arranged on an electrochemical device, and a processor can be arranged on a charging device.

[0085] The embodiment of the present application also provides an electrochemical device, which includes a processor and a computer-readable storage medium. The initial discharge cut-off voltage of the electrochemical device is a first voltage, and the initial charge cut-off voltage is a second voltage. The computer-readable storage medium stores computer-executable instructions that can be executed by the processor, and when the processor executes the computer-executable instructions, the control method steps described in any of the above embodiments are implemented.

[0086] In some embodiments, the processor is used to: when the internal resistance change rate of the electrochemical device is less than a first threshold value, control the electrochemical device to charge and discharge at a first voltage and a second voltage; when the internal resistance change rate of the electrochemical device is greater than or equal to the first threshold value and less than or equal to the second threshold value, increase the discharge cut-off voltage of the electrochemical device by a first increase amount, wherein the second threshold value is greater than the first threshold value; when the internal resistance change rate of the electrochemical device is greater than the second threshold value, perform operations related to the charge and discharge state of the electrochemical device.

[0087] In some embodiments, the electrochemical device includes a negative electrode sheet, the negative electrode sheet includes a negative electrode active material layer, and the negative electrode active material layer includes a 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 mass of the Si element in the negative electrode active material layer accounts for 1% to 90% of the mass of the negative electrode active material layer.

[0088] In some embodiments, the first voltage is 2.5V to 3.5V, and the second voltage is 4.2V to 4.6V. In some embodiments, the first threshold satisfies: 1% ≤ first threshold ≤ 10%. In some embodiments, the second threshold satisfies 10% < second threshold ≤ 20%. In some embodiments, the value range of the first boost is 0.03V to 0.6V. In some embodiments, performing operations related to the charge and discharge state of the electrochemical device includes at least one of steps d) to e): d) stopping the charge and discharge operation of the electrochemical device; e) sending a prompt message to stop the charge and discharge operation of the electrochemical device.

[0089] By adopting the electrochemical device of the present application, the high energy density characteristics of the electrochemical device can be fully utilized in the early stage when the internal resistance change rate is small. In addition, during the cycle, it can be determined whether to increase the discharge cut-off voltage of the electrochemical device by a first increase amount or perform operations related to the charge and discharge state of the electrochemical device according to the internal resistance change rate state of the electrochemical device, thereby maintaining the high energy density of the electrochemical device while improving the cycle life of the electrochemical device.

[0090] The present application also provides a charging device, such as Figure 2 As shown, the charging device 500 includes a processor 501 and a machine-readable storage medium 502. The charging device 500 may also include a detection circuit module 503, a charge and discharge circuit 504, an interface 505, a power interface 506, and a rectifier circuit 507. Among them, the detection circuit module 503 is used to detect the internal resistance change rate of the lithium-ion battery and send the detection result to the processor 501; the charge and discharge circuit 504 is used to receive instructions issued by the processor 501 to charge or discharge the lithium-ion battery 605; the interface 505 is used to be electrically connected to the lithium-ion battery 605; the power interface 506 is used to connect to an external power supply; the rectifier circuit 507 is used to rectify the input current; the machine-readable storage medium 502 stores machine-executable instructions that can be executed by the processor, and when the processor 501 executes the machine-executable instructions, the method steps described in any of the above implementation schemes are implemented.

[0091] The present application also provides a system, such as Figure 3As shown, the system 600 includes a second processor 601 and a second machine-readable storage medium 602. The system 600 may also include a detection circuit module 603, a charge and discharge circuit 604, a lithium-ion battery 605, and a second interface 606. Among them, the detection circuit module 603 is used to detect the internal resistance change rate of the lithium-ion battery 605 and send the detection result to the second processor 601; the charge and discharge circuit 604 is used to receive instructions issued by the second processor 601, so as to charge or discharge the lithium-ion battery 605; the second interface 606 is used to connect with the interface of the external charger 700; the external charger 700 is used to provide power; the second machine-readable storage medium 602 stores machine-executable instructions that can be executed by the processor, and when the second processor 601 executes the machine-executable instructions, the method steps described in any of the above implementation schemes are implemented. The external charger 700 may include a first processor 701, a first machine-readable storage medium 702, a first interface 703, and a corresponding rectifier circuit. The external charger may be a commercially available charger, and the embodiment of the present application does not specifically limit its structure. The present application embodiment also provides a computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by the processor, the control method steps described in any of the above embodiments are implemented. The computer-readable storage medium may include a random access memory (Random Access Memory, referred to as RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage. Optionally, the memory may also be at least one storage device located away from the aforementioned processor. The above-mentioned processor may be a general-purpose processor, including a central processing unit (Central Processing Unit, referred to as CPU), a network processor (Network Processor, referred to as NP), etc.; it may also be a digital signal processor (Digital Signal Processing, referred to as DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, referred to as ASIC), a field programmable gate array (Field-Programmable Gate Array, referred to as FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. It should be understood that the above-mentioned processor may be included in an electrochemical device, a charging device, or an electronic device (e.g., a mobile phone, etc.) containing an electrochemical device.

[0092] The embodiment of the present application also provides an electronic device including the above-mentioned electrochemical device. The electronic device of the embodiment of the present application is not particularly limited, and it can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a drone, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium ion capacitor, etc. Exemplarily, the electronic device can be a mobile phone, a tablet computer, etc., with a built-in lithium ion battery and a device with data processing capabilities.

[0093] As for the charging device / electrochemical device / computer-readable storage medium / electronic device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0094] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features. For example, the above features are replaced with the technical features with similar functions disclosed in the present application.

Claims

1. A control method for an electrochemical device, the control method comprising: In response to the internal resistance change rate of the electrochemical device being greater than or equal to a first threshold, increasing the discharge cut-off voltage of the electrochemical device or performing an operation related to the charge and discharge state of the electrochemical device; Wherein, in response to the internal resistance change rate of the electrochemical device being greater than or equal to the first threshold, increasing the discharge cut-off voltage of the electrochemical device or performing an operation step related to the charge and discharge state of the electrochemical device includes: In response to the internal resistance change rate of the electrochemical device being greater than or equal to the first threshold and less than or equal to a second threshold, increasing the discharge cut-off voltage of the electrochemical device, wherein the second threshold is greater than the first threshold; In response to the internal resistance change rate of the electrochemical device being greater than the second threshold, performing an operation related to the charge and discharge state of the electrochemical device, the second threshold satisfying 11%≤second threshold≤15%; The performing of the operation related to the charge and discharge state of the electrochemical device comprises at least one of steps a) to b): a) stopping the charge and discharge operation of the electrochemical device; b) sending a prompt message for stopping the charge and discharge operation of the electrochemical device.

2. The control method of an electrochemical device according to claim 1, wherein: The electrochemical device includes a negative electrode sheet, the negative electrode sheet includes a negative electrode active material layer, and the negative electrode active material layer includes a silicon-based material.

3. The control method of the electrochemical device according to claim 2, wherein: The mass of the Si element in the negative electrode active material layer accounts for 1% to 90% of the mass of the negative electrode active material layer.

4. The control method of the electrochemical device according to claim 3, wherein: The mass of the Si element in the negative electrode active material layer accounts for 5% to 50% of the mass of the negative electrode active material layer.

5. The control method of the electrochemical device according to claim 4, wherein: The mass of the Si element in the negative electrode active material layer accounts for 5% to 20% of the mass of the negative electrode active material layer.

6. The control method of an electrochemical device according to claim 1, wherein: The first threshold satisfies: 1%≤first threshold≤10%.

7. The control method of an electrochemical device according to claim 1, wherein: The step of increasing the discharge cut-off voltage of the electrochemical device comprises increasing the discharge cut-off voltage of the electrochemical device by 0.03V to 0.6V.

8. A computer-readable storage medium, wherein: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method according to any one of claims 1 to 7 is implemented.

9. A charging device, comprising a processor and a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions that can be executed by the processor, and when the processor executes the computer-executable instructions, the control method according to any one of claims 1 to 7 is implemented.

10. An electrochemical device, wherein: The invention comprises a processor and a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions that can be executed by the processor, and when the processor executes the computer-executable instructions, a control method is implemented, and the control method comprises: In response to the internal resistance change rate of the electrochemical device being greater than or equal to a first threshold, increasing the discharge cut-off voltage of the electrochemical device or performing an operation related to the charge and discharge state of the electrochemical device; Wherein, in response to the internal resistance change rate of the electrochemical device being greater than or equal to the first threshold, increasing the discharge cut-off voltage of the electrochemical device or performing operation steps related to the charge and discharge state of the electrochemical device includes: In response to the internal resistance change rate of the electrochemical device being greater than or equal to the first threshold and less than or equal to a second threshold, increasing the discharge cut-off voltage of the electrochemical device, wherein the second threshold is greater than the first threshold; In response to the internal resistance change rate of the electrochemical device being greater than the second threshold, performing an operation related to the charge and discharge state of the electrochemical device, the second threshold satisfying 11%≤second threshold≤15%; The performing of the operation related to the charge and discharge state of the electrochemical device comprises at least one of steps a) to b): a) stopping the charge and discharge operation of the electrochemical device; b) sending a prompt message for stopping the charge and discharge operation of the electrochemical device.

11. The electrochemical device according to claim 10, wherein: The electrochemical device includes a negative electrode sheet, the negative electrode sheet includes a negative electrode active material layer, and the negative electrode active material layer includes a silicon-based material.

12. The electrochemical device according to claim 11, wherein The mass of the Si element in the negative electrode active material layer accounts for 1% to 90% of the mass of the negative electrode active material layer.

13. The electrochemical device according to claim 12, wherein: The mass of the Si element in the negative electrode active material layer accounts for 5% to 50% of the mass of the negative electrode active material layer.

14. The electrochemical device according to claim 13, wherein: The mass of the Si element in the negative electrode active material layer accounts for 5% to 20% of the mass of the negative electrode active material layer.

15. The electrochemical device according to claim 10, wherein: The first threshold satisfies: 1%≤first threshold≤10%.

16. The electrochemical device according to claim 10, wherein: The step of increasing the discharge cut-off voltage of the electrochemical device comprises increasing the discharge cut-off voltage of the electrochemical device by 0.03V to 0.6V.

17. An electronic device comprising the electrochemical device according to any one of claims 10 to 16.

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