Semi-solid battery, energy storage device and electric equipment

Abstract

The application provides a semi-solid battery, an energy storage device and an electric equipment. The semi-solid battery comprises an electrode sheet, the electrode sheet comprises a current collector and an active material layer, a composite electrolyte layer is arranged on at least one surface of the electrode sheet, the composite electrolyte layer comprises a polymer electrolyte and polymer fibers, the polymer fibers are distributed between the polymer electrolytes, and the single-face thickness of the composite electrolyte layer is 50 microns to 100 microns.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemistry, and in particular to a semi-solid battery, an energy storage device and an electric device. BACKGROUND

[0002] Lithium ion batteries have the characteristics of high specific energy, high working voltage, low self-discharge rate, small size and light weight, and are widely used in various fields such as electric energy storage, portable electronic devices and electric vehicles.

[0003] Semi-solid electrolyte is a kind of electrolyte between liquid electrolyte and pure solid electrolyte. The semi-solid battery developed based on semi-solid electrolyte has better safety performance, but the cycle performance still needs to be improved. How to improve the cycle performance of the semi-solid battery becomes a technical problem to be solved. SUMMARY

[0004] In order to solve the above technical problems, the present application discloses a semi-solid battery, an energy storage device and an electric device to improve the cycle performance of the semi-solid battery.

[0005] In a first aspect, the present application provides a semi-solid battery, comprising an electrode sheet, the electrode sheet comprising a current collector and an active material layer, wherein a composite electrolyte layer is included on at least one surface of the electrode sheet, the composite electrolyte layer comprising a polymer electrolyte and a polymer fiber, the polymer fiber being distributed between the polymer electrolytes, and the single-sided thickness of the composite electrolyte layer being 50 μm to 100 μm.

[0006] In some embodiments of the present application, the composite electrolyte layer is a multi-layer structure, each layer in the multi-layer structure being a composite electrolyte sub-layer formed by the polymer electrolyte and the polymer fiber, and the composite electrolyte sub-layers being stacked to form the composite electrolyte layer.

[0007] In some embodiments of the present application, the number of layers of the multi-layer structure in the composite electrolyte layer is 1 to 3.

[0008] In some embodiments of the present application, the polymer fiber forms a polymer fiber layer, and the polymer fiber layer is embedded in the composite electrolyte layer.

[0009] In some embodiments of the present application, the single-sided thickness of the polymer fiber layer is 5 μm to 10 μm.

[0010] In some embodiments of the present application, in the composite electrolyte layer, the ionic conductivity of the polymer electrolyte is 13 x 10 -4 S / cm to 16 x 10 -4 S / cm.

[0011] In some embodiments of the present application, the electrode tab includes a positive electrode tab and a negative electrode tab, the positive electrode tab has one side of the composite electrolyte layer disposed opposite to one side of the composite electrolyte layer of the negative electrode tab.

[0012] In some embodiments of the present application, the first polymer material in the polymer electrolyte includes at least one of polyethylene oxide, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polypropylene carbonate, and polycyanoacrylate.

[0013] In some embodiments of the present application, the second polymer material in the polymer fiber includes at least one of polylactic acid, polycarbonate, polyethylene, and polycaprolactone.

[0014] In a second aspect, the present application provides an energy storage device, including a box body and at least one semi-solid battery of the first aspect, the semi-solid battery is accommodated in the box body.

[0015] In a third aspect, the present application provides an electrical equipment, including the energy storage device of the second aspect, the energy storage device supplies power to the electrical equipment.

[0016] Compared with the prior art, the present application has at least the following beneficial effects:

[0017] The present application provides a semi-solid battery, an energy storage device, and an electrical equipment. The semi-solid battery includes an electrode tab, the electrode tab includes a current collector and an active material layer, and at least one surface of the electrode tab includes a composite electrolyte layer. The composite electrolyte layer includes a polymer electrolyte and a polymer fiber, the polymer fiber is distributed between the polymer electrolyte, the single surface thickness of the composite electrolyte layer is 50 μm to 100 μm, the polymer electrolyte is separated into a large number of micro-structures by the polymer fiber, the micro-structures are beneficial to increase the amorphous area of the polymer electrolyte and improve the ionic conductivity of the polymer electrolyte; the polymer fiber improves the mechanical properties of the composite electrolyte layer, effectively reduces the risk of lithium dendrite formation and internal short circuit; and the polymer fiber also has an adsorption effect on the polymer electrolyte, improving the liquid retention capacity of the polymer electrolyte. The lithium ion semi-solid battery of the present application has the above structure, and the thickness of the composite electrolyte layer is regulated within the scope of the present application, which is beneficial to reduce the ionic conductivity while maintaining high liquid retention rate and tensile strength, so as to improve the cycle performance of the lithium ion semi-solid battery. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 Structure diagram of an electrode tab according to an embodiment of the present application;

[0020] Figure 2 Structure diagram of an electrode tab according to another embodiment of the present application;

[0021] Figure 3 Structure diagram of a composite electrolyte layer according to an embodiment of the present application;

[0022] Figure 4 Structure diagram of an electrode tab according to another embodiment of the present application;

[0023] Figure 5 Structure diagram of a household energy storage system according to an embodiment of the present application;

[0024] Figure 6 Structure diagram of an energy storage system according to an embodiment of the present application.

[0025] Legend: 1-energy storage device, 2-electric energy conversion device, 3-first user load, 4-second user load, 10-electrode tab, 11-current collector, 12-active material layer, 13-composite electrolyte layer, 131-polymer electrolyte, 132-polymer fiber, 133-composite electrolyte sublayer, 400-energy storage system, 410-high voltage cable, 420-first electric energy conversion device, 430-second electric energy conversion device. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0027] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0028] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0029] In addition, the terms "mount", "set", "provided with", "connected", "connected" should be broadly understood. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] In addition, the terms "first", "second" and the like are mainly used to distinguish different devices, elements or components (the specific type and structure can be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise stated, the meaning of "multiple" is two or more.

[0031] It should be noted that in the content of the present application, the lithium ion semi-solid battery is taken as an example of a semi-solid battery to explain the present application, but the semi-solid battery of the present application is not limited to the lithium ion semi-solid battery.

[0032] The present application provides a semi-solid battery, as shown in Figure 1 The semi-solid battery includes an electrode tab 10, the electrode tab includes a current collector 11 and an active material layer 12, and a composite electrolyte layer 13 is included on at least one surface of the electrode tab, specifically, the composite electrolyte layer can be located on the surface of the active material layer. The composite electrolyte layer includes a polymer electrolyte 131 and a polymer fiber 132, the polymer fiber is distributed between the polymer electrolytes, and the single-sided thickness of the composite electrolyte layer is 50 μm to 100 μm. For example, the single-sided thickness of the composite electrolyte layer is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0033] The inventors have found that the conduction of lithium ions in the polymer electrolyte mainly includes the coordination and dissociation processes of lithium ions and oxygen functional groups. Due to the electric field, lithium ions are constantly coordinated and dissociated with oxygen functional groups, and quickly conduct with the thermal motion of polymer chain segments. The conduction of lithium ions mainly includes the local motion of the chain interior and between the chains of the polymer chain segment, and the migrating ions include ions and ion clusters. The migration rate of lithium ions in the amorphous phase is much higher than that in the crystalline phase, and the ionic conductivity in the amorphous phase is usually 2-3 orders of magnitude higher. Based on the above findings, in the electrode sheet of the semi-solid battery of the present application, the polymer electrolyte therein is separated into a large number of micro-structure by polymer fibers, which is beneficial to increase the area of the amorphous region of the polymer electrolyte, thereby improving the ionic conductivity of the polymer electrolyte and increasing the migration rate of lithium ions; and the polymer fibers improve the mechanical properties of the composite electrolyte layer, effectively reducing the risk of lithium dendrite formation and internal short circuit; and the polymer fibers also have an adsorption effect on the polymer electrolyte, improving the liquid retention capacity of the polymer electrolyte. The inventors have also found that the thickness of the composite electrolyte layer should not be too small or too large. When the thickness of the composite electrolyte layer is too small (e.g. less than 50 μm), the liquid retention capacity of the polymer electrolyte decreases, and at the same time the mechanical strength of the composite electrolyte layer decreases significantly, resulting in a decrease in the mechanical strength of the electrode sheet, which is not conducive to the improvement of the cycle performance of the lithium ion semi-solid battery; when the thickness of the composite electrolyte layer is too large (e.g. greater than 100 μm), the ionic conductivity decreases significantly, which is also not conducive to the improvement of the cycle performance of the lithium ion semi-solid battery. The lithium ion semi-solid battery of the present application has the above structure, and the thickness of the composite electrolyte layer is controlled within the scope of the present application, which is beneficial to reduce the ionic conductivity while maintaining high liquid retention rate and tensile strength, so as to improve the cycle performance of the lithium ion semi-solid battery.

[0034] In the present application, the composite electrolyte layer is included on at least one surface of the electrode sheet, as shown in Figure 1 , the composite electrolyte layer 13 can be included on one surface of the electrode sheet; or, as shown in Figure 2 , the composite electrolyte layer 13 is included on both surfaces of the electrode sheet.

[0035] In some embodiments of the present application, as shown in Figure 3 , the composite electrolyte layer 13 can be a multi-layer structure, each layer of the multi-layer structure being a composite electrolyte sub-layer 133 formed by the compounding of a polymer electrolyte and a polymer fiber, and the multi-layer composite electrolyte sub-layers are stacked to form the composite electrolyte layer. The composite electrolyte layer of the present application can be a single-layer structure; or the composite electrolyte layer can be a multi-layer structure, which is beneficial to enhance the mechanical strength of the composite electrolyte layer and prevent the internal short circuit caused by the penetration of lithium dendrites into the composite electrolyte layer.

[0036] In some embodiments of the present application, the number of layers of the multilayer structure in the composite electrolyte layer is 1-3, for example, the number of layers of the multilayer structure is 1 layer, 2 layers or 3 layers. In this way, it is beneficial to enhance the mechanical strength of the composite electrolyte layer, prevent lithium dendrites from piercing the composite electrolyte layer to cause internal short circuit, while reducing the ionic conductivity and internal resistance, and it is beneficial to improve the capacity, capacity retention rate and energy efficiency of the lithium ion semi-solid-state battery.

[0037] In some embodiments of the present application, the polymer fibers form a polymer fiber layer, and the polymer fiber layer is embedded in the composite electrolyte layer. In this way, the polymer fiber layer in the composite electrolyte layer can be sufficiently distributed between the polymer electrolytes, which is beneficial to improve the ionic conductivity of the polymer electrolyte.

[0038] In some embodiments of the present application, the single-sided thickness of the polymer fiber layer is 5 μm-10 μm, for example, the single-sided thickness is 5 μm, 7 μm, 9 μm or 10 μm. By adjusting the single-sided thickness of the polymer fiber layer within the above range, it is beneficial to obtain a polymer fiber layer with good liquid retention capacity and mechanical strength.

[0039] In some embodiments of the present application, in the composite electrolyte layer, the ionic conductivity of the polymer electrolyte is 13×10 -4 S / cm-16×10 -4 S / cm, for example, the ionic conductivity of the polymer electrolyte is 13×10 -4 S / cm, 14×10 -4 S / cm, 15×10 -4 S / cm or 16×10 -4 S / cm, which has excellent ionic conductivity performance.

[0040] In some embodiments of the present application, as shown in Figure 4 The electrode sheet includes a positive electrode sheet and a negative electrode sheet, and one side of the positive electrode sheet with the composite electrolyte layer 13 is arranged opposite to one side of the negative electrode sheet with the composite electrolyte layer 13. In this way, it is beneficial to obtain the lithium ion semi-solid-state battery of the present application. Figure 4 In some embodiments of the present application, when the upper electrode sheet is a positive electrode sheet, the lower electrode sheet can be a negative electrode sheet; when the upper electrode sheet is a negative electrode sheet, the lower electrode sheet can be a positive electrode sheet, which is not particularly limited in the present application.

[0041] In some embodiments of the present application, the first polymer material in the polymer electrolyte includes at least one of polyethylene oxide (PEO), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polypropylene carbonate (PPC) and polycyanoacrylate (PCA).

[0042] In some embodiments of the present application, the second polymer material in the polymer fiber comprises at least one of polylactic acid (PLA), polycarbonate (PC), polyethylene (PE), and polycaprolactone (PCL).

[0043] The preparation method of the composite electrolyte layer is not particularly limited in the present application, as long as the composite electrolyte layer of the present application can be obtained. Illustratively, the composite electrolyte layer can be prepared by the following preparation steps:

[0044] Preparation of the polymer electrolyte glue solution: the first polymer material is mixed with the first solvent at a mass ratio of 1:8 to 1:10, and stirred to prepare a first glue solution; wherein the first solvent can be selected from at least one of deionized water, ethanol, ethyl acetate, isopropanol, N,N-dimethylformamide, cyclohexane, N-methyl pyrrolidone, and tetrahydrofuran; then a photo-curing agent is added to the first glue solution and stirred uniformly to obtain a second glue solution, wherein the content of the photo-curing agent in the second glue solution is 0.3wt% to 0.6wt%; then a liquid electrolyte is added to the second glue solution and stirred uniformly to obtain a polymer electrolyte glue solution, wherein the content of the liquid electrolyte in the polymer electrolyte glue solution is 8wt% to 12wt%;

[0045] Preparation of the electrospinning solution: the second polymer material is mixed with the second solvent at a mass ratio of 1:15 to 1:25, and stirred uniformly to obtain an electrospinning solution; the second solvent can be selected from at least one of methanol, diethyl ether, acetone, propanol, methyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran;

[0046] Preparation of the composite electrolyte layer:

[0047] Step S1, the polymer electrolyte glue solution is coated on the surface of the active material layer of the electrode tab, to form a polymer electrolyte coating layer, and then the electrospinning solution is sprayed on the surface of the polymer electrolyte coating layer by an electrospinning device to form a polymer fiber, the polymer fiber is infiltrated by the uncured polymer electrolyte coating layer and embedded into the polymer electrolyte coating layer, to form a composite electrolyte layer initial structure;

[0048] Step S2, the electrode tab with the composite electrolyte layer initial structure obtained in step S1 is placed under a light source for irradiation, and the irradiation time is 60s to 120s; the polymer electrolyte coating layer in the composite electrolyte layer initial structure is cured after being irradiated by light, to form the composite electrolyte layer structure of the present application.

[0049] In an alternative embodiment, step S1 can be repeated to obtain a multi-layer composite electrolyte layer initial structure, and then the light curing is performed uniformly, which is conducive to improving the interface contact effect between layers; in another alternative embodiment, after obtaining a composite electrolyte layer initial structure, the composite electrolyte layer initial structure can be subjected to light curing alone, and thus, the thickness of the composite electrolyte layer can be more accurately controlled.

[0050] The liquid electrolyte is not particularly limited in the present application, and can be selected by those skilled in the art according to actual needs, as long as the purpose of the present application can be achieved. For example, at least one of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP), propyl propionate (PP), methyl ethyl carbonate (EMC), dimethyl carbonate (DMC), vinyl carbonate (VC) or fluoroethylene carbonate (FEC) is mixed in a certain mass ratio or volume ratio to obtain a non-aqueous organic solvent, and then a lithium salt is added, dissolved and uniformly mixed. The type of lithium salt is not limited in the present application, as long as the purpose of the present application can be achieved. For example, the lithium salt can include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, lithium bis(oxalato)borate (LiBOB) or lithium difluoroborate. The concentration of lithium salt in the liquid electrolyte is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, the concentration of lithium salt is 1.0 mol / L to 2.0 mol / L.

[0051] The thickness of the polymer fiber layer generally increases with the increase of the spraying time and / or spraying amount of electrospinning, and the thickness of the polymer fiber layer can be adjusted by adjusting the spraying time and / or spraying amount during electrospinning, which is not particularly limited in the present application.

[0052] It can be understood that the thickness of the composite electrolyte layer is mainly affected by the thickness of the polymer electrolyte coating, and therefore, the thickness of the polymer electrolyte coating can be adjusted by adjusting the coating amount of the polymer electrolyte glue, so as to adjust the thickness of the composite electrolyte layer.

[0053] The photo-curing agent of the present application can be at least one of 2,4,6-trimethylbenzoyl ethyl phosphate, 4-dimethylamino-ethyl benzoate, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone. Light curing has the advantages of simple reaction equipment, short reaction time and good controllability, and the composite electrolyte layer initial structure can be cured by light curing method when the composite electrolyte layer structure is prepared.

[0054] The semi-solid battery of the present application includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet generally includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer can be provided on one surface in the thickness direction of the positive electrode current collector or on both surfaces. In the present application, the positive electrode active material layer is provided on the surface of the positive electrode current collector, i.e., the positive electrode active material layer can be provided in part of the area of one surface of the positive electrode current collector or in the entire area of one surface of the positive electrode current collector. The positive electrode current collector is not particularly limited in the present application as long as the object of the present application can be achieved, and for example, can include but is not limited to an aluminum foil, an aluminum alloy foil, or a composite current collector. In the present application, the thickness of the positive electrode current collector is not particularly limited as long as the object of the present application can be achieved, and for example, the thickness is 8 μm to 13 μm. The single-sided thickness of the positive electrode active material layer of the present application can be 100 μm to 200 μm.

[0055] In the present application, the positive electrode active material layer includes a positive electrode active material. The positive electrode active material is not particularly limited in the present application as long as the object of the present application can be achieved, and for example, can include at least one of lithium iron phosphate, a lithium-rich manganese-based material, lithium cobaltate, lithium manganate, and lithium iron manganese phosphate.

[0056] In the present application, the positive electrode active material layer can further include a positive electrode binder. The positive electrode binder is not particularly limited in the present application as long as the object of the present application can be achieved, and for example, can include but is not limited to at least one of a fluorine-containing resin, a polypropylene resin, a fiber-type binder, a rubber-type binder, or a polyimide-type binder.

[0057] The negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer can be provided on one surface or both surfaces in the thickness direction of the negative electrode current collector. In the present application, the negative electrode active material layer is provided on the surface of the negative electrode current collector, i.e., the negative electrode active material layer can be provided in part of the area of one surface of the negative electrode current collector or in the entire area of one surface of the negative electrode current collector. The negative electrode current collector is not particularly limited in the present application as long as the object of the present application can be achieved, and for example, can include but is not limited to a copper foil, a copper alloy foil, a nickel foil, or a composite current collector. In the present application, the thickness of the negative electrode current collector is not particularly limited as long as the object of the present application can be achieved, and for example, the thickness is 4 μm to 12 μm. The single-sided thickness of the negative electrode active material layer of the present application can be 70 μm to 200 μm.

[0058] In the present application, the negative electrode active material layer includes a negative electrode active material. The negative electrode active material is not particularly limited in the present application as long as the object of the present application can be achieved, and for example, can include at least one of artificial graphite, natural graphite, mesocarbon microbeads, silicon, or silicon carbon.

[0059] In the present application, the negative active material layer can further include a negative binder. The present application does not have a particular limitation on the negative binder as long as the purpose of the present application can be achieved, for example, can include at least one of acrylate, polyamide, polyimide, polyamide-imide, polyvinylidene fluoride (PVDF), butadiene styrene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose.

[0060] The lithium ion semi-solid battery of the present application further includes a shell, and the present application does not have a particular limitation on the shell, which can be selected by a person skilled in the art according to actual needs as long as the purpose of the present application can be achieved. For example, the shell can include an aluminum plastic film.

[0061] The present application does not have a particular limitation on the preparation method of the semi-solid battery, and a preparation method known in the art can be selected as long as the purpose of the present application can be achieved. For example, the preparation method of the lithium ion semi-solid battery includes but is not limited to the following steps: stacking the positive electrode sheet and the negative electrode sheet in order, and arranging the one side of the positive electrode sheet having the composite electrolyte layer opposite to the one side of the negative electrode sheet having the composite electrolyte layer, and winding, folding, etc. according to needs to obtain a bare battery cell with a winding structure, and placing the bare battery cell into a packaging bag to obtain a lithium ion semi-solid battery.

[0062] The present application further provides an energy storage device including a box body and at least one semi-solid battery of any of the above embodiments, and the lithium ion semi-solid battery is accommodated in the box body. The energy storage device with the semi-solid battery has excellent performance, which is beneficial to the use of the energy storage device. By accommodating the semi-solid battery in the box body, the fixing and protection of the semi-solid battery can be increased, and the service life of the energy storage device can be improved. It can be understood that the energy storage device can have one or more semi-solid batteries, and when the energy storage device contains multiple semi-solid batteries, the multiple semi-solid batteries can be connected by at least one of parallel connection and series connection.

[0063] The present application further provides an electrical equipment including the energy storage device of the above embodiments, which is beneficial to improve the product competitiveness and use performance of the electrical equipment. In an alternative embodiment, the electrical equipment includes an electrical equipment body, and the energy storage device is used to power the electrical equipment body. In an alternative embodiment, the electrical equipment body includes a device positive electrode and a device negative electrode, and the positive electrode sheet of the lithium ion semi-solid battery in the energy storage device is used to electrically connect the device positive electrode of the electrical equipment body, and the negative electrode sheet of the lithium ion semi-solid battery in the energy storage device is used to electrically connect the device negative electrode of the electrical equipment body, so as to power the electrical equipment.

[0064] The power consuming device of the present application can include, but is not limited to, a container, a household energy storage system, an electric vehicle, an electric automobile, a ship, a spacecraft, an electric toy and an electric tool, etc., wherein the spacecraft is, for example, an airplane, a rocket, a space shuttle and a spacecraft, etc., the electric toy includes, for example, a fixed or mobile electric toy, and specifically, for example, an electric automobile toy, an electric ship toy and an electric airplane toy, etc., and the electric tool includes, for example, a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, and specifically, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator and an electric planer.

[0065] Referring to Figure 5 , Figure 5 FIG. 1 is a structural schematic diagram of a household energy storage system according to an embodiment of the present application, and the present application Figure 5 The embodiment takes a household energy storage scenario in user side energy storage as an example for illustration, and the energy storage device of the present application is not limited to the household energy storage scenario.

[0066] The present application provides a household energy storage system, which includes an electric energy conversion device 2 (a photovoltaic panel), a first user load 3 (a street lamp), a second user load 4 (for example, a household appliance such as an air conditioner, etc.), and an energy storage device 1. The energy storage device 1 is a small energy storage box, which can be installed on an outdoor wall by a wall hanging manner. Specifically, the photovoltaic panel can convert solar energy into electric energy during a low electricity price period, and the energy storage device 1 is used to store the electric energy and supply the street lamp and the household appliance for use during a high electricity price period, or supply power during a power grid outage.

[0067] Referring to Figure 6 , Figure 6 FIG. 2 is a structural schematic diagram of an energy storage system 400 according to an embodiment of the present application, and the present application Figure 6 The embodiment takes a distribution side shared energy storage scenario as an example for illustration, and the energy storage device 1 of the present application is not limited to the distribution side shared energy storage scenario.

[0068] The application provides a kind of energy storage system 400, energy storage system 400 includes: high voltage cable 410, first electric energy conversion device 420, second electric energy conversion device 430 and the energy storage device 1 provided by the application, under the condition of power generation, first electric energy conversion device 420 and second electric energy conversion device 430 are used to convert other forms of energy into electric energy, connect with high voltage cable 410 and supply for distribution network electricity side use, when electricity load is low, first electric energy conversion device 420, second electric energy conversion device 430 generates excess, and the electric quantity of more generation is stored to energy storage device 1, reduces the rate of abandoned wind, abandoned light, improves new energy power generation consumption problem;When electricity load is high, grid issues instructions, the electric quantity stored in energy storage device 1 is transmitted to electricity side use by grid-connected mode with high voltage cable 410, provides peak shaving, frequency modulation, backup and other services for grid operation, fully plays the role of grid peak shaving, promotes grid peak clipping, relieves grid power supply pressure.

[0069] Optionally, the first electric energy conversion device 420 and the second electric energy conversion device 430 can convert at least one of solar energy, light energy, wind energy, heat energy, tidal energy, biomass energy and mechanical energy into electric energy.

[0070] The number of energy storage devices 1 can be multiple, and the multiple energy storage devices 1 are connected in series or parallel with each other, and the multiple energy storage devices 1 are supported and electrically connected by isolation plates (not shown in the figure). In the embodiment, "multiple" means two or more. The energy storage device 1 can also be provided with an energy storage box outside for accommodating the energy storage device 1.

[0071] Optionally, the energy storage device 1 can include but is not limited to a battery module, a battery pack, a battery system, etc. The battery module can be formed by connecting a plurality of lithium ion semi-solid state batteries in series / parallel, the battery pack can include a plurality of lithium ion semi-solid state batteries, and the battery system can be a charging and discharging system including the lithium ion semi-solid state battery or the battery pack.

[0072] The actual application form of the energy storage device 1 provided by the embodiment of the application can be but is not limited to the listed products, and can also be other application forms. The embodiment of the application does not strictly limit the application form of the energy storage device 1. The embodiment of the application only takes the energy storage device 1 as an example of a multi-core battery. When the energy storage device 1 is a single battery, the energy storage device 1 can be at least one of a cylindrical battery and a square battery.

[0073] Embodiment

[0074] In the following, preparation examples, examples and comparative examples are given to more specifically describe the embodiments of the application. Various tests and evaluations are carried out according to the following methods.

[0075] Example 1

[0076] <Preparation of polymer electrolyte glue>

[0077] The first polymer material (PEO and PMMA mixed in a mass ratio of 1:1) is mixed with the first solvent N-methyl pyrrolidone (NMP) in a mass ratio of 1:10, and stirred to prepare a first glue. Then, a photocuring agent is added to the first glue and stirred uniformly to obtain a second glue, and the content of the photocuring agent in the second glue is 0.5wt%. Then, a liquid electrolyte is added to the second glue and stirred uniformly to obtain a polymer electrolyte glue, and the content of the liquid electrolyte in the polymer electrolyte glue is 10wt%. The preparation process of the liquid electrolyte is as follows: in an argon atmosphere glove box with a water content of ≤1ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (EMC) are mixed in a mass ratio of 1:1:1, then lithium salt LiPF6 is added and dissolved into the above solvent, and after mixing uniformly, an electrolyte is obtained. The molar concentration of LiPF6 in the electrolyte is 1mol / L.

[0078] <Preparation of electrospinning solution>

[0079] The second polymer material PLA is mixed with the second solvent N,N-dimethylformamide in a mass ratio of 1:20, and stirred uniformly to obtain an electrospinning solution.

[0080] <Preparation of positive electrode sheet>

[0081] The positive active material lithium iron phosphate (LiFePO4), conductive carbon black (Super-P), and binder PVDF are mixed in a mass ratio of 97:0.7:2.3; then NMP is added as a solvent to prepare a positive electrode slurry with a solid content of 60wt%, and stirred uniformly; then the positive electrode slurry is uniformly coated on one surface of a positive current collector aluminum foil with a thickness of 10μm, and dried at 85℃; then the above steps are repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided coated positive active material layer. The single-sided thickness of the positive active material layer is 100μm.

[0082] The polymer electrolyte glue is coated on one surface of the positive active material layer to form a polymer electrolyte coating layer, and then the electrospinning liquid is sprayed on the surface of the polymer electrolyte coating layer by the electrospinning equipment to form polymer fibers. After the polymer fibers are infiltrated and embedded into the inside of the unsolidified polymer electrolyte coating layer, an initial structure of the composite electrolyte layer is formed. Then, the positive electrode sheet with the initial structure of the composite electrolyte layer is placed under a light source for irradiation, and the irradiation time is 60 s. After the polymer electrolyte coating layer in the initial structure of the composite electrolyte layer is solidified after being irradiated, the composite electrolyte layer is formed. Then, the above steps are repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with the composite electrolyte layer on both surfaces. The single-sided thickness of the composite electrolyte layer is 50 μm, and the single-sided thickness of the polymer fiber layer is 5 μm.

[0083] <Preparation of a negative electrode sheet>

[0084] The negative active material artificial graphite, conductive carbon black (Super-P), thickening agent carboxymethyl cellulose (CMC), binder styrene-butadiene rubber (SBR) are mixed according to the mass ratio of 96.5:0.5:1:2, deionized water is added, and a negative electrode slurry with a solid content of 50wt% is prepared and uniformly stirred. The negative electrode slurry is uniformly coated on one surface of a negative current collector copper foil with a thickness of 6 μm, and dried at 85°C. Then, the above steps are repeated on the other surface of the copper foil to obtain a negative electrode sheet with a negative active material layer coated on both surfaces. The single-sided thickness of the negative active material layer is 70 μm.

[0085] The polymer electrolyte glue is coated on one surface of the positive active material layer to form a polymer electrolyte coating layer, and then the electrospinning liquid is sprayed on the surface of the polymer electrolyte coating layer by the electrospinning equipment to form polymer fibers. After the polymer fibers are infiltrated and embedded into the inside of the unsolidified polymer electrolyte coating layer, an initial structure of the composite electrolyte layer is formed. Then, the positive electrode sheet with the initial structure of the composite electrolyte layer is placed under a light source for irradiation, and the irradiation time is 60 s. After the polymer electrolyte coating layer in the initial structure of the composite electrolyte layer is solidified after being irradiated, the composite electrolyte layer is formed. Then, the above steps are repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with the composite electrolyte layer on both surfaces. The single-sided thickness of the composite electrolyte layer is 50 μm, and the single-sided thickness of the polymer fiber layer is 5 μm.

[0086] <Preparation of a lithium ion semi-solid-state battery>

[0087] The positive electrode sheet, the negative electrode sheet prepared above are stacked in sequence, and the one side of the positive electrode sheet with the composite electrolyte layer is arranged opposite to the one side of the negative electrode sheet with the composite electrolyte layer, to assemble a button cell, and the specific assembly sequence from bottom to top is negative shell → negative electrode sheet → separator → positive electrode sheet → gasket → spring sheet → positive shell, and the assembled button cell is subjected to packaging, standing, formation and other processes to obtain a button lithium ion semi-solid state battery, and the shell size of the button cell used is 2430 model, the positive electrode sheet size is 14 mm in diameter, the negative electrode sheet size is 16 mm in diameter, and the separator size is 19 mm in diameter.

[0088] Examples 2-5

[0089] Except that the single-sided thickness of the composite electrolyte layer is adjusted according to Table 1 in <Preparation of positive electrode sheet> and <Preparation of negative electrode sheet>, the rest is the same as Example 1.

[0090] Examples 6-7

[0091] Except that the single-sided thickness of the polymer fiber layer is adjusted according to Table 1 in <Preparation of positive electrode sheet> and <Preparation of negative electrode sheet>, the rest is the same as Example 5.

[0092] Examples 8-10

[0093] Except that the types of the first polymer material and the second polymer material are adjusted according to Table 2 in <Preparation of positive electrode sheet> and <Preparation of negative electrode sheet>, the rest is the same as Example 5.

[0094] Example 11

[0095] Except that <Preparation of positive electrode sheet> and <Preparation of negative electrode sheet> are different from Example 5, the rest is the same as Example 5.

[0096] Preparation of positive electrode sheet

[0097] The positive active material lithium iron phosphate (LiFePO4), conductive carbon black (Super-P), and binder PVDF are mixed in a mass ratio of 97:0.7:2.3; then N-methyl pyrrolidone (NMP) is added as a solvent to prepare a positive electrode slurry with a solid content of 60wt%, and then stirred uniformly; then the positive electrode slurry is uniformly coated on one surface of a positive current collector aluminum foil with a thickness of 10μm, and dried at 85℃; then the above steps are repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided coated positive active material layer. The single-sided thickness of the positive active material layer is 100μm;

[0098] Step 1, polymer electrolyte glue is coated on one surface of the positive active material layer, forming a polymer electrolyte coating, and then electrospinning liquid is sprayed on the surface of the polymer electrolyte coating by electrospinning equipment to form polymer fibers, the polymer fibers are infiltrated by the uncured polymer electrolyte coating and embedded in the polymer electrolyte coating, and then a first layer of composite electrolyte layer initial structure is formed, in which the single-sided thickness of the polymer fiber layer is 5 μm; repeat step 1 above, to form a second layer of composite electrolyte layer initial structure, in which the single-sided thickness of the polymer fiber layer is 5 μm; Step 2, the obtained positive electrode sheet is placed under a light source for irradiation, the irradiation time is 60 s, and the polymer electrolyte coating in the first layer of composite electrolyte layer and the second layer of composite electrolyte layer is cured after being irradiated, forming a composite electrolyte layer with a multi-layer structure. Then, repeat steps 1 and 2 above on the other surface of the aluminum foil to obtain a positive electrode sheet with a composite electrolyte layer on both sides. The total single-sided thickness of the composite electrolyte layer is 100 μm, and the total single-sided thickness of the polymer fiber layer is 10 μm.

[0099] <Preparation of a negative electrode sheet>

[0100] The negative active material artificial graphite, conductive carbon black (Super-P), thickening agent carboxymethyl cellulose (CMC), binder styrene-butadiene rubber (SBR) are mixed according to the mass ratio of 96.5:0.5:1:2, deionized water is added, and a negative electrode slurry with a solid content of 50wt% is prepared, and then stirred uniformly. The negative electrode slurry is uniformly coated on one surface of the negative current collector copper foil with a thickness of 6 μm, and then dried at 85°C; then repeat the above steps on the other surface of the copper foil to obtain a negative electrode sheet with a negative active material layer coated on both sides. The single-sided thickness of the negative active material layer is 70 μm;

[0101] Step 1', polymer electrolyte glue is coated on one surface of the above negative electrode active material layer to form a polymer electrolyte coating layer, and then electrospinning liquid is sprayed on the surface of the polymer electrolyte coating layer by an electrospinning device to form a polymer fiber, which is infiltrated by the uncured polymer electrolyte coating layer and embedded into the polymer electrolyte coating layer, and then a first layer of composite electrolyte layer initial structure is formed, in which the single-sided thickness of the polymer fiber layer is 5 μm; the above step 1' is repeated to form a second layer of composite electrolyte layer initial structure, in which the single-sided thickness of the polymer fiber layer is 5 μm; Step 2', the obtained negative electrode sheet is placed under a light source for irradiation, the irradiation time is 60 s, and the polymer electrolyte coating layer in the first layer of composite electrolyte layer and the second layer of composite electrolyte layer is cured after being irradiated by light, thereby forming a composite electrolyte layer with a multi-layer structure. Then, the above steps 1' and 2' are repeated on the other surface of the aluminum foil to obtain a negative electrode sheet with a composite electrolyte layer on both sides. Among them, the total single-sided thickness of the composite electrolyte layer is 100 μm, and the total single-sided thickness of the polymer fiber layer is 10 μm.

[0102] Comparative Example 1

[0103] Except that in the <preparation of positive electrode sheet> and <preparation of negative electrode sheet>, no electrospinning liquid is sprayed on the surface of the polymer electrolyte coating layer, that is, the formed electrolyte layer does not have a polymer fiber, and the rest is the same as Example 1.

[0104] Comparative Example 2

[0105] Except that in the <preparation of positive electrode sheet> and <preparation of negative electrode sheet>, no electrospinning liquid is sprayed on the surface of the polymer electrolyte coating layer, that is, the formed electrolyte layer does not have a polymer fiber, and the rest is the same as Example 3.

[0106] Comparative Example 3

[0107] Except that in the <preparation of positive electrode sheet> and <preparation of negative electrode sheet>, no electrospinning liquid is sprayed on the surface of the polymer electrolyte coating layer, that is, the formed electrolyte layer does not have a polymer fiber, and the rest is the same as Example 5.

[0108] Comparative Example 4-Comparative Example 5

[0109] Except that in the <preparation of positive electrode sheet> and <preparation of negative electrode sheet>, the single-sided thickness of the composite electrolyte layer is adjusted according to Table 1, and the rest is the same as Example 1.

[0110] Table 1 Related preparation parameters of Example 1-Example 7 and Comparative Example 1-Comparative Example 5

[0111]

[0112] Note: In Table 1, " / " means that the relevant preparation parameter does not exist.

[0113] Table 2 Relevant preparation parameters of Example 5, Example 8 to Example 10

[0114] First polymer material class Second polymer material class Example 5 PEO:PMMA = 1 : 1 PLA Example 8 PAN:PVDF = 1 : 1 PE Example 9 PPC:PCA = 1 : 1 PC Example 10 PEO:PMMA = 1 : 3 PLA

[0115] Test method and equipment:

[0116] Ion conductivity test:

[0117] The gel-like polymer electrolyte was assembled into a simulated button cell with a stainless steel / polymer electrolyte / stainless steel structure in an argon atmosphere glove box. After standing for 12 h, electrochemical impedance spectroscopy (EIS) test was performed using a Princeton electrochemical test system, the test frequency range was 0.1 Hz to 10 kHz, and the excitation voltage was 5 mV; the ion conductivity δ of the polymer electrolyte was calculated according to formula (1), in which l is the film thickness of the polymer electrolyte film, S is the area of the polymer electrolyte film, and Re is the bulk resistance of the polymer electrolyte film.

[0118] δ = l / (Re·S) (1)

[0119] Liquid retention rate test:

[0120] After the polymer electrolyte was coated on a flat glass in an argon atmosphere glove box according to different thicknesses, a semi-solid electrolyte film layer was formed after light curing, and was weighed, recorded as m1; then it was stored in a dry culture dish for 7 days, and was weighed again, recorded as m2, the liquid retention rate = (m2 / m1) x 100%.

[0121] Tensile strength test:

[0122] The cured polymer electrolyte film (thickness of 50 μm) was cut into a sample with a length of 7 cm and a width of 2.5 cm using a dumbbell-shaped sample knife, and a universal material testing machine was used to perform tensile test on the sample, the tensile speed was 10 mm / min, the ratio of the maximum force F borne by the sample during the tensile process to the original cross-sectional area S of the sample was called the tensile strength σ (as formula (2)), and the unit was MPa.

[0123] σ = F / S (2)

[0124] Cycle retention rate test:

[0125] The button lithium ion semi-solid batteries prepared from each of the examples and the comparative examples were subjected to constant current charge-discharge test at 0.1 times rate (C) and 1C (1C = 160 mA / g) respectively, the charging voltage was 2.5 V to 4.2 V, and the capacity retention rate after cycling was calculated. The capacity retention rate calculation formula was: 200th cycle capacity retention rate = (discharge capacity after the 200th cycle / discharge capacity of the first cycle) x 100%.

[0126] Table 3: Performance data of each of the examples and the comparative examples

[0127]

[0128] In combination with Table 1 and Table 3, it can be seen from Example 1 and Comparative Example 1, Example 3 and Comparative Example 2, and Example 5 and Comparative Example 3 that when the electrolyte layer does not have polymer fibers (for example, Comparative Examples 1 to 3), that is, the lithium ion semi-solid battery does not have the composite electrolyte layer of the present application, the ion conductivity, liquid retention rate and tensile strength performance of Comparative Examples 1 to 3 are obviously low, resulting in that the 0.1C cycle discharge capacity retention rate and 1C cycle discharge capacity retention rate of the battery are obviously low; while the lithium ion semi-solid battery of Example 1 of the present application has a composite electrolyte layer, the ion conductivity, liquid retention rate and tensile strength are obviously improved compared with Comparative Example 1, thereby obviously improving the 0.1C cycle discharge capacity retention rate and 1C cycle discharge capacity retention rate. Similarly, the cycle performance of the lithium ion semi-solid batteries of Example 3 and Example 5 of the present application is also obviously improved compared with Comparative Example 2 and Comparative Example 3, respectively.

[0129] The single-sided thickness of the composite electrolyte layer and the single-sided thickness of the polymer fiber layer in the electrode tab also generally affect the performance of the lithium ion semi-solid battery. As can be seen from Examples 1 to 7, on the basis of having the composite electrolyte layer structure of the present application, by adjusting the above parameters within the scope of the present application, it is beneficial to improve the ion conductivity while maintaining high liquid retention rate and tensile strength, so that the cycle performance of the lithium ion semi-solid battery is improved.

[0130] As can be seen from Example 1 and Comparative Examples 4-5, when the thickness of the single surface of the composite electrolyte layer in the electrode tab is too thin (for example, Comparative Example 4), the ionic conductivity, liquid retention rate, and tensile strength of the lithium ion semi-solid-state battery are low, which leads to a significant decrease in the 0.1C cycle discharge capacity retention rate and the 1C cycle discharge capacity retention rate of the battery, which may be due to the fact that the composite electrolyte layer is too thin, the storage space for the liquid in the polymer electrolyte is insufficient, the electrolyte is consumed too quickly, and the mechanical strength of the composite electrolyte layer is reduced, and the reduction in strength will further reduce the inhibition of lithium precipitation at the interface, and there is a risk of short circuit due to piercing of the electrolyte layer; when the thickness of the single surface of the composite electrolyte layer in the electrode tab is too thick (for example, Comparative Example 5), although the tensile strength of the lithium ion semi-solid-state battery is high, the ionic conductivity is significantly low, which leads to a low 0.1C cycle discharge capacity retention rate and 1C cycle discharge capacity retention rate of the battery, which may be due to the fact that the composite electrolyte layer is too thick, which increases the internal impedance of the composite electrolyte layer and affects the cycle performance of the battery; by adjusting the thickness of the single surface of the composite electrolyte layer in the electrode tab within the scope of the present application, it is beneficial to reduce the ionic conductivity while maintaining high liquid retention rate and tensile strength, so that the lithium ion semi-solid-state battery exhibits excellent cycle performance.

[0131] The types of the first polymer material and the second polymer material also generally affect the performance of the lithium ion semi-solid-state battery. As can be seen from Example 5, Examples 8-10, by adjusting the above parameters within the scope of the present application based on the composite electrolyte layer structure of the present application, it is beneficial to improve the ionic conductivity while maintaining high liquid retention rate and tensile strength, so that the cycle performance of the lithium ion semi-solid-state battery is improved.

[0132] As can be seen from Example 11 and Example 5, the lithium ion semi-solid-state battery with a multi-layer structure has further improved ionic conductivity, liquid retention rate, and tensile strength, so that the cycle performance of the lithium ion semi-solid-state battery is further improved.

[0133] The above describes in detail a semi-solid-state battery, an energy storage device, and an electrical equipment according to the present application. The principles and implementation modes of the present application are described by applying specific examples. The above examples are only used to help understand the technical solutions and core invention points of the embodiments of the present application. Meanwhile, for those skilled in the art, the specific implementation modes and application ranges can be changed according to the idea of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A semi-solid battery, characterized by, The electrode tab comprises a current collector and an active material layer, wherein, The composite electrolyte layer comprises a polymer electrolyte and polymer fibers, the polymer fibers are distributed between the polymer electrolyte, the single surface thickness of the composite electrolyte layer is 50-100 μm; the composite electrolyte layer is a multi-layer structure, each layer of the multi-layer structure is a composite electrolyte sub-layer formed by the polymer electrolyte and the polymer fibers, the composite electrolyte sub-layers are stacked to form the composite electrolyte layer; the polymer fibers form a polymer fiber layer, the polymer fiber layer is embedded in the composite electrolyte layer; the single surface thickness of the polymer fiber layer is 5-10 μm.

2. The semi-solid battery of claim 1, wherein, The number of layers of the multi-layer structure in the composite electrolyte layer is 2-3.

3. The semi-solid battery of claim 1, wherein, The ionic conductivity of the polymer electrolyte in the composite electrolyte layer is 13 x 10 -4 S / cm~16 x 10 -4 S / cm.

4. The semi-solid battery of claim 1, wherein, The electrode tab comprises a positive electrode tab and a negative electrode tab, one side of the positive electrode tab with the composite electrolyte layer is arranged opposite to one side of the negative electrode tab with the composite electrolyte layer.

5. The semi-solid battery of claim 1, wherein, The polymer electrolyte comprises a first polymer material, the first polymer material comprises at least one of polyethylene oxide, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polypropylene carbonate and polycyanoacrylate.

6. The semi-solid battery of claim 1, wherein, The polymer fibers comprise a second polymer material, the second polymer material comprises at least one of polylactic acid, polycarbonate, polyethylene and polycaprolactone.

7. An energy storage device, characterized by, The energy storage device comprises a box and at least one semi-solid battery according to any one of claims 1-6, the semi-solid battery is accommodated in the box.

8. An electric device, characterized by The energy storage device comprises the energy storage device for supplying power to the electric device.

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