Composite porous membrane, preparation method therefor, battery and electrical device

Abstract

Disclosed in the present application are a composite porous membrane, a preparation method therefor, a battery and an electrical device. The composite porous membrane comprises an organic polymer substrate and an inorganic electrolyte, the inorganic electrolyte being dispersed in the organic polymer substrate. A plurality of holes of different diameters are formed in the composite porous membrane, the ionic conductivity of the composite porous membrane being 1*10-4 S / cm-5*10-4 S / cm. Thus, the organic polymer substrate, the inorganic electrolyte and the holes in the composite porous membrane can all transport active metal ions, which increases transport paths of the active metal ions, thereby increasing the transport rate of the active metal ions and accordingly improving the power performance of batteries.

Description

Composite porous membrane and preparation method, battery, and electrical equipment Technical Field

[0001] The present application relates to the field of batteries, and in particular to a composite porous membrane and a preparation method thereof, a battery and an electrical device. Background Art

[0002] Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment, aerospace and other fields. Semi-solid batteries are batteries in which part of the electrolyte is solid. Because of their advantages such as high energy density, high safety and long life, they are considered to be one of the most promising power sources for the next generation of electric vehicles and energy storage products. In-situ polymerization semi-solid batteries refer to batteries formed by in-situ curing technology. Specifically, they are formed by injecting liquefied monomers into the interior of the battery cell by liquid injection, and inducing in-situ polymerization of the monomers to form a film under certain conditions. Curing the electrolyte through in-situ curing technology will result in a loss of battery power performance.

[0003] Summary of the Invention

[0004] In view of the technical problems existing in the background technology, the present application provides a composite porous membrane that can increase the migration rate of active metal ions and thereby improve the power performance of the battery.

[0005] The first aspect of the present application provides a composite porous membrane, the composite porous membrane comprising an organic polymer substrate and an inorganic electrolyte, the inorganic electrolyte being dispersed in the organic polymer substrate, the composite porous membrane being formed with pores of different pore sizes, and the ionic conductivity of the composite porous membrane being 1×10 -4 S / cm-5×10 -4 S / cm. As a result, the pores in the organic polymer substrate, inorganic electrolyte, and composite porous membrane can all realize the transmission of active metal ions, increasing the transmission path of active metal ions, thereby increasing the transmission rate of active metal ions and improving the power performance of the battery.

[0006] According to some embodiments of the present application, the ionic conductivity of the composite porous membrane is 2×10 -4 S / cm-5×10 -4 S / cm. Thus, the transport capacity of the composite porous membrane for active metal ions is improved, thereby improving the power performance of the battery.

[0007] According to some embodiments of the present application, the mass ratio of the organic polymer substrate to the inorganic electrolyte is 3-5.67, thereby improving the ionic conductivity of the composite porous membrane, improving the composite porous membrane's ability to transport active metal ions, and improving the power performance of the battery.

[0008] According to some embodiments of the present application, the composite porous membrane satisfies one or more of the following conditions: the organic polymer accounts for 75% to 85% of the total mass of the composite porous membrane; and the inorganic electrolyte accounts for 15% to 25% of the total mass of the composite porous membrane. Thus, a higher content of the organic polymer can reduce the effect of the inorganic electrolyte on the porosity of the composite porous membrane and improve the transport rate of the composite porous membrane to the remaining liquid electrolyte.

[0009] According to some embodiments of the present application, the composite porous membrane meets one or more of the following conditions: the organic polymer substrate includes one or more of polyvinylidene fluoride, polyhexafluoropropylene, polyvinyl chloride, polyacrylonitrile, polystyrene, polyvinyl acetate, polymethyl methacrylate, and polyethylene dimethacrylate; and the inorganic electrolyte includes one or more of silica, alumina, lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, and lithium aluminum germanium phosphide. Thus, the above-mentioned organic polymers and inorganic electrolytes can transport active metal ions, improving the power performance of the battery.

[0010] According to some embodiments of the present application, the pores of varying sizes have a pore diameter of 0.5 nm to 5 μm. By ensuring that the pore diameters of the composite porous membrane are within this range, the small pores can restrict the passage of polyanion-based ions, increasing the number of active metal ions migrating and enhancing the battery's capacity, while the large pores can transmit liquid electrolyte, increasing the migration rate of active metal ions.

[0011] According to some embodiments of the present application, the porosity of the composite porous membrane is 40%-70%, thereby increasing the migration rate of active metal ions and improving the power performance of the battery.

[0012] According to some embodiments of the present application, the thickness of the composite porous membrane is 8 μm-20 μm, thereby providing multi-dimensional channels for the transmission of active metal ions and improving the transmission rate of active metal ions.

[0013] The second aspect of the present application provides a method for preparing the composite porous membrane of the first aspect of the present application, comprising mixing an organic polymer and an inorganic electrolyte, heating to form a membrane, and forming pores in the membrane to form a composite porous membrane having pores of different sizes, wherein the ionic conductivity of the composite porous membrane is 1×10 -4 S / cm-5×10 -4S / cm. Thus, the composite porous membrane prepared by this method has all the characteristics and advantages of the aforementioned composite porous membranes, which will not be repeated here. In general, it has at least the advantages of high active metal ion migration rate and excellent battery power performance.

[0014] According to some embodiments of the present application, the method includes mixing the organic polymer, the inorganic electrolyte, and the pore-forming agent, and heating and drying the mixture to form the composite porous membrane. Thus, pores of varying sizes are formed in the composite porous membrane, facilitating the transmission of the liquid electrolyte, thereby increasing the migration rate of active metal ions and improving the power performance of the battery.

[0015] A third aspect of the present application provides a battery comprising the composite porous membrane provided in the first aspect of the present application or a composite porous membrane prepared by the method provided in the second aspect of the present application. Thus, the battery possesses all the features and advantages of the aforementioned composite porous membranes, which are not further elaborated here. In general, it has at least the advantage of excellent power performance.

[0016] According to some embodiments of the present application, the battery comprises a semi-solid-state battery, thereby improving the power performance of the semi-solid-state battery.

[0017] The fourth aspect of the present application provides an electrical device, including the battery provided in the third aspect of the present application.

[0018] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0020] FIG1 is a schematic diagram of a battery according to one embodiment of the present application.

[0021] FIG. 2 is an exploded view of the battery according to one embodiment of the present application shown in FIG. 1 .

[0022] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0023] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0024] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0025] FIG6 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0026] FIG7 is a SEM image of the composite porous membrane in Example 2 of the present application.

[0027] FIG8 is an enlarged view of FIG7.

[0028] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 semi-solid battery; 51 housing; 52 electrode assembly; 53 cover plate. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0030] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0032] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0033] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0034] Currently, market developments indicate that batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As battery applications continue to expand, market demand is also growing.

[0035] In-situ polymerization semi-solid-state batteries can effectively reduce the content of liquid electrolyte in the battery. While increasing the battery's energy density, the reduction in liquid electrolyte content can reduce side reactions caused by the liquid electrolyte and increase the battery's service life. However, during the in-situ polymerization process, as the in-situ polymerization reaction proceeds, the solidified electrolyte will clog the pores of the separator. The transport of active metal ions can only rely on the peristalsis of the polymer segments. Compared to the transport of active metal ions through the liquid electrolyte, the transport of active metal ions through the peristalsis of solid polymer segments will reduce the transport rate of active metal ions, thereby reducing the power performance of the battery. The clogged pores of the separator will also hinder the flow of the remaining liquid electrolyte, further reducing the transport rate of active metal ions. The migration of active metal ions during charge and discharge is hindered, reducing the battery's capacity.

[0036] The present application proposes a composite porous membrane. The composite porous membrane has a high ionic conductivity, which can improve the transmission capacity of active metal ions and improve the power performance of the battery. Specifically, the composite porous membrane includes an organic polymer substrate and an inorganic electrolyte. The organic polymer substrate can transmit active metal ions through the peristalsis of the chain segments. The inorganic electrolyte can continuously fill vacancies with active metal ions and escape from the vacancies to transmit active metal ions. The composite porous membrane is also formed with holes of different pore sizes. The holes of different pore sizes can allow the remaining liquid electrolyte in the semi-solid battery to pass through, and then transmit active metal ions through the liquid electrolyte. The multiple transmission modes of active metal ions increase the transmission rate of active metal ions, which can improve the power performance of the battery. The flow of liquid electrolyte in pores of different pore sizes can also reduce the resistance to the transmission of active metal ions during charging and discharging, increase the number of active metal ions that migrate, and thus improve the performance of the battery capacity.

[0037] The composite porous membrane proposed in this application can be used with a battery, and the battery disclosed in the embodiments of this application can be used in electrical devices that use a battery as a power source or various energy storage systems that use a battery as an energy storage element. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0038] In a first aspect, the present application provides a composite porous membrane comprising an organic polymer substrate and an inorganic electrolyte, wherein the inorganic electrolyte is dispersed in the organic polymer substrate, and the composite porous membrane is provided with a plurality of pores of different pore sizes, wherein the ionic conductivity of the composite porous membrane is 1×10 -4 S / cm-5×10 -4 S / cm.

[0039] The composite porous membrane proposed in this application has a high ionic conductivity and can be directly placed in the battery for the transmission of active metal ions without going through the in-situ polymerization reaction process, which can reduce the risk of solid electrolyte formed during the curing process clogging the isolation membrane. At the same time, the composite isolation membrane has a high ionic conductivity, which can improve the transmission capacity of active metal ions and improve the power performance of the battery. Specifically, when the composite porous membrane is placed in a semi-solid battery, the organic polymer substrate can transmit active metal ions through the creep of the chain segments; during the charging process, the active metal ions near the inorganic electrolyte on the negative electrode side move to the negative electrode, and vacancies are generated in the inorganic electrolyte near the negative electrode. The active metal ions can continuously fill the vacancies and then escape from the vacancies to transmit the active metal ions; the composite porous membrane is also formed with pores of different pore sizes. The pores with larger pore sizes allow the liquid electrolyte to pass through, and then transmit the active metal ions through the liquid electrolyte; by transmitting active metal ions in the above multiple ways, the transmission rate of the active metal ions is increased, and the power performance of the battery can be improved; the pores with smaller pore sizes allow the solvated active metal ions with smaller ionic radius to pass through, while the polymer-based anions with larger ionic radius cannot pass through, which can increase the number of active metal ions migrating on both sides of the composite porous membrane and improve the battery capacity. At the same time, the flow of liquid electrolyte in the pores can also reduce the resistance to the transmission of active metal ions during charging and discharging, increase the number of active metal ions migrating, and thus improve the battery capacity.

[0040] In the present application, the test method for the ionic conductivity of the composite porous membrane is a method based on a confined symmetrical cell, and the conductivity of the composite porous membrane is calculated by measuring the Rs obtained by the symmetrical cell EIS of composite porous membranes with different numbers of layers.

[0041] In the present application, active metal ions include lithium ions.

[0042] According to some embodiments of the present application, the ionic conductivity of the composite porous membrane can be 1×10 -4 S / cm-5×10 -4 S / cm. For example, it can be 1×10 -4 S / cm, 1.5×10 -4 S / cm, 2×10 -4 S / cm, 2.5×10 -4 S / cm, 3×10 -4 S / cm, 3.5×10 -4 S / cm, 4×10 -4 S / cm, 4.5×10 -4 S / cm or 5×10 -4 S / cm, etc., or can be a range of any of the above values. In this way, the transport capacity of the composite porous membrane for active metal ions can be improved, and the power performance of the battery can be improved. According to some specific embodiments of the present application, the ionic conductivity of the composite porous membrane can be 2×10 -4 S / cm-5×10 -4 S / cm.

[0043] According to some embodiments of the present application, the ratio of the mass of the organic polymer substrate to the mass of the inorganic electrolyte can be 3-5.67. For example, it can be 3, 3.5, 4, 4.5, 5, 5.5 or 5.67, or it can be a range composed of any of the above numerical values. Thus, the organic polymer substrate has a higher content as a framework, which reduces the filling rate of the inorganic electrolyte to the pores and increases the transmission rate of the composite porous membrane to the remaining liquid electrolyte. According to some specific embodiments of the present application, the ratio of the mass of the organic polymer substrate to the mass of the inorganic electrolyte can be 3.5-5.

[0044] In this application, the content of organic polymers and inorganic electrolytes can be tested by thermogravimetric analysis. Specifically, the following steps are performed: 1. Sample preparation: Weigh approximately 50 mg of sample into an Al2O3 crucible and shake flat; 2. Parameter settings: Nitrogen atmosphere, purge gas 60 mL / min, shielding gas 20 mL / min; 3. Temperature ramp: 10°C / min, 35°C-600°C. The organic polymer decomposes at high temperatures, and the mass of the remaining sample is the mass of the inorganic electrolyte. The difference in mass before and after the test is the organic polymer content.

[0045] According to some embodiments of the present application, the mass proportion of the organic polymer based on the total mass of the composite porous membrane can be 75%-85%, for example, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84% or 85%, or can be a range consisting of any of the above values. As a result, the content of organic polymer in the composite porous membrane is relatively high, which can reduce the weight of the composite porous membrane and improve the energy density of the battery.

[0046] According to some embodiments of the present application, based on the total mass of the composite porous membrane, the mass proportion of the inorganic electrolyte is 15%-25%, for example, it can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%, etc., or it can be a range composed of any of the above values. As a result, the content of the inorganic electrolyte is relatively low, which can reduce the effect of the inorganic electrolyte on the porosity and increase the transmission rate of the composite porous membrane to the remaining liquid electrolyte. At the same time, it can also reduce the weight of the composite porous membrane and increase the energy density of the battery.

[0047] According to some embodiments of the present application, the organic polymer substrate may include one or more of polyvinylidene fluoride, polyhexafluoropropylene, polyvinyl chloride, polyacrylonitrile, polystyrene, polyvinyl acetate, polymethyl methacrylate, and polyethylene dimethacrylate. Thus, the above-mentioned organic polymers can be directly formed into a composite porous membrane and placed in a battery. During the charge and discharge process, the active metal ions are conducted through the creep of the polymer chain segments, thereby improving the composite porous membrane's resistance to active metal ions.

[0048] According to some embodiments of the present application, the inorganic electrolyte includes one or more of silicon dioxide, aluminum oxide, lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, and lithium aluminum germanium phosphate. Thus, the inorganic electrolytes of these types can continuously fill vacancies with active metal ions and then release them from the vacancies to transport active metal ions, thereby improving the transport efficiency of active metal ions.

[0049] According to some embodiments of the present application, the pore size of the plurality of pores may range from 0.5 nm to 5 μm. In other words, the pore size of the larger pore among the plurality of pores is less than or equal to 5 μm, and the pore size of the smaller pore is greater than or equal to 0.5 nm. Thus, pores of different pore sizes are formed on the composite porous membrane. The large pores can achieve rapid transmission of liquid electrolyte and improve the transmission rate of active metal ions. The small pores can allow solvated active metal ions to pass through, while polymer-based anions with larger ionic radius cannot pass through, thereby increasing the number of active metal ions that migrate, thereby improving the performance of the battery capacity.

[0050] In the present application, the pore sizes of pores of different sizes can be measured by scanning electron microscopy. Specifically, the pore sizes and numbers of all pores in a certain area can be measured and then the average value can be calculated.

[0051] According to some embodiments of the present application, the porosity of the composite porous membrane can be 40%-70%. For example, it can be 40%, 45%, 50%, 55%, 60%, 65%, or 70%, or any range thereof. Thus, by ensuring that the porosity of the composite porous membrane is within the above range, the transmission rate of active metal ions is increased, thereby improving the power performance of the battery.

[0052] In this application, the porosity testing method is as follows: the composite porous membrane is pretreated in a drying room: use tweezers to select >20 pieces of composite porous membrane and put them into the sample cup, record the number of pieces, and calculate the apparent volume; testing: place the sample cup containing the sample in a true density tester, close the test system, introduce helium according to the procedure, detect the pressure of the gas in the sample chamber and the expansion chamber, and then calculate the true volume according to Bohr's law (PV=nRT), thereby obtaining the porosity of the sample to be tested.

[0053] According to some embodiments of the present application, the thickness of the composite porous membrane is 8 μm to 20 μm. For example, the thickness may be 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, or 20 μm, or any range thereof. This improves the power performance of the battery while reducing the probability of battery self-discharge.

[0054] In the present application, the thickness of the composite porous membrane can be measured by a micrometer.

[0055] The second aspect of the present application provides a method for preparing the composite porous membrane provided in the first aspect of the present application, comprising: mixing an organic polymer and an inorganic electrolyte, heating to form a membrane, and forming pores in the membrane to form a composite porous membrane having a plurality of pores of different pore sizes, wherein the ionic conductivity of the composite porous membrane is 1×10 -4 S / cm-5×10 -4S / cm. Specifically, the organic polymer and the inorganic electrolyte are mixed, heated and stirred to form a uniformly mixed glue, and the glue is extruded through an extruder to obtain a membrane structure, and the membrane structure is subjected to pore making to obtain a composite porous membrane with pores of different pore sizes. Thus, the composite porous membrane prepared by this method has high ionic conductivity, can improve the transmission capacity of active metal ions, and improve the power performance of the battery. Specifically, when the composite porous membrane is placed in a semi-solid battery, both the organic polymer substrate and the inorganic electrolyte can directly transmit active metal ions, and pores of different pore sizes are also formed on the composite porous membrane. The pores with larger pore sizes can allow liquid electrolyte to pass through, and then the active metal ions are transmitted through the liquid electrolyte. The multiple transmission modes of active metal ions improve the transmission rate of active metal ions, and thus the power performance of the battery can be improved.

[0056] According to some embodiments of the present application, the method may further include mixing the organic polymer, the inorganic electrolyte, and the pore-forming agent, and heating and drying to form the composite porous membrane. Specifically, the organic polymer, the inorganic electrolyte, and the pore-forming agent are mixed, heated and stirred to form a uniformly mixed glue solution, the glue solution is extruded through an extruder, and dried to obtain a membrane structure, and pores are formed in the membrane structure to obtain a composite porous membrane having multiple pores of different pore sizes.

[0057] As an example, the temperature for heating the organic polymer, the inorganic electrolyte, and the pore-forming agent can be 50° C. to 90° C., for example, 50° C., 60° C., 70° C., 80° C., or 90° C., or any range thereof. This allows the organic polymer and the inorganic electrolyte to be in a liquid state, thereby improving the uniformity of the mixing of the organic polymer and the inorganic electrolyte.

[0058] According to some embodiments of the present application, the ratio of the mass of the organic polymer substrate to the mass of the inorganic electrolyte can be 3-5.67. For example, it can be 3, 3.5, 4, 4.5, 5, 5.5 or 5.67, or it can be a range composed of any of the above numerical values. Thus, the organic polymer substrate has a higher content as a framework, which reduces the filling rate of the inorganic electrolyte to the pores and increases the transmission rate of the composite porous membrane to the remaining liquid electrolyte. According to some specific embodiments of the present application, the ratio of the mass of the organic polymer substrate to the mass of the inorganic electrolyte can be 3.5-5.

[0059] A third aspect of the present application provides a battery comprising the composite porous membrane provided in the first aspect of the present application or a composite porous membrane prepared by the method provided in the second aspect of the present application. Thus, the battery possesses all the features and advantages of the aforementioned composite porous membranes, which are not further elaborated here. In general, it has at least the advantage of excellent power performance.

[0060] As an example, the battery comprises a semi-solid state battery.

[0061] Typically, a semi-solid-state battery consists of a positive electrode and a negative electrode. During the battery's charge and discharge process, active metal ions are embedded in and out of the positive and negative electrodes.

[0062] [Positive electrode]

[0063] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer includes the positive electrode active material of the first aspect of the present application.

[0064] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0065] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0066] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material may adopt the positive electrode active material for lithium-ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0067] The modified compounds of the above materials may be doping-modified and / or surface-coated modified materials.

[0068] [Negative electrode]

[0069] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0070] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0071] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0072] In some embodiments, the negative electrode active material may adopt negative electrode active materials for batteries that are well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and titanates. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. When the battery is a lithium-ion battery, lithium titanate is used as the titanate; when the battery is a sodium-ion battery, sodium titanate is used as the titanate. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0073] In some embodiments, the negative electrode active material layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0074] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0075] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0076] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0077] [Electrolyte]

[0078] In some embodiments, the semi-solid state battery may further include a liquid electrolyte.

[0079] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0080] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0081] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0082] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0083] In some embodiments, the semi-solid state battery may further include a separator.

[0084] [Isolation film]

[0085] The present application has no particular limitation on the type of isolation membrane, and any known isolation membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0086] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0087] In some embodiments, the positive electrode sheet and the negative electrode sheet in the semi-solid state battery can be made into an electrode assembly through a winding process or a lamination process.

[0088] In some embodiments, the semi-solid-state battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0089] In some embodiments, the outer packaging of the semi-solid-state battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0090] The present application has no particular limitation on the shape of the semi-solid-state battery, which can be cylindrical, square, or any other shape. For example, FIG1 shows a semi-solid-state battery 5 having a square structure as an example.

[0091] In some embodiments, referring to Figure 2, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0092] In some embodiments, semi-solid batteries can be assembled into battery modules. The number of semi-solid batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0093] Figure 3 shows an example battery module 4. Referring to Figure 3 , within the battery module 4, multiple semi-solid batteries 5 can be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple semi-solid batteries 5 can be secured using fasteners.

[0094] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of semi-solid batteries 5 are received in the receiving space.

[0095] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0096] Figures 4 and 5 illustrate an example battery pack 1. Referring to Figures 4 and 5 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0097] In addition, the present application also provides an electrical device comprising the semi-solid-state battery provided herein. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0098] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0099] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0100] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0101] Example 1

[0102] 1. Preparation of positive electrode sheet

[0103] NCM96 (Ni 0.94 Co 0.03 Mn 0.03 O2), superconducting carbon (SuperP), and polyvinylidene fluoride (PVDF) are added to N-methylpyrrolidone (NMP) in a mass ratio of 97%:1%:2%, stirred evenly under the action of a vacuum mixer, coated on both sides of the aluminum foil, dried in an oven, and cold pressed to obtain the positive electrode sheet.

[0104] 2. Preparation of negative electrode sheet

[0105] Artificial graphite and silicon-carbon composite material (the mass ratio of artificial graphite and silicon-carbon composite material is 6:4), conductive agent carbon black, carbon nanotubes (CNT), binder styrene-butadiene rubber (SBR), and thickener sodium hydroxymethyl cellulose (CMCNa) are added into deionized water in a weight ratio of 94.5%: 1%: 0.375%: 2.8%: 1.325%, mixed and stirred evenly, coated on both sides of the negative electrode current collector copper foil, dried in an oven, and cold pressed to obtain the negative electrode sheet.

[0106] 3. Prepare electrolyte

[0107] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. The fully dried electrolyte salt LiPF6 was dissolved in the above solvent and mixed evenly to obtain an electrolyte solution with a concentration of 1 mol / L.

[0108] 4. Composite porous membrane

[0109] The organic polymer polyvinylidene fluoride, the inorganic electrolyte silica, the pore-forming agent mineral oil and the plasticizer butyl phthalate are stirred at 70°C to form a glue solution. Based on the total mass of the glue solution, the mass ratio of the organic polymer, the inorganic electrolyte, the pore-forming agent and the plasticizer is 63.75%:21.25%:13%:2%. The rotation speed is 100 r / min and the time is 1 hour to obtain a mixed glue solution. The mixed glue solution is defoamed and extruded by an extruder and spread flat on the carrier surface of a mirror roller. After drying, a composite porous membrane can be obtained.

[0110] 5. Preparation of lithium-ion batteries

[0111] The positive electrode sheet, composite porous membrane, and negative electrode sheet are wound in sequence to form a bare cell. The bare cell is placed in a packaging shell, dried, and then injected with electrolyte. After vacuum packaging, standing, forming, and shaping, a lithium-ion battery is obtained. The liquid electrolyte content in the lithium-ion battery is 0.4g / Ah.

[0112] The preparation methods of the semi-solid state batteries in Examples 2 to 12, Comparative Examples 2 and 3 are the same as those in Example 1. The differences are detailed in Table 1.

[0113] Preparation of semi-solid-state battery in Comparative Example 1:

[0114] 1. The preparation method of the positive electrode sheet and the negative electrode sheet is the same as that of Example 1. The positive electrode sheet and the negative electrode sheet are wound in sequence to obtain a bare battery cell.

[0115] 2. In-situ polymerization to form an isolation film

[0116] Vinylene carbonate, acrylonitrile (AN) monomer and azobisisobutyronitrile (AIBN) initiator are added to an electrolyte solvent, wherein the electrolyte solvent is ethylene carbonate (EC):diethyl carbonate (DEC):ethyl methyl carbonate (EMC), wherein the volume ratio of EC:DEC:EMC is 1:1:1, the mass proportion of EC, DEC and EMC in the electrolyte is 20%, the mass proportion of propylene monomer in the electrolyte is 9%, and the mass proportion of azobisisobutyronitrile in the electrolyte is 1%. Additives fluoroethylene carbonate (FEC), lithium bistrifluoromethanesulfonyl imide and lithium hexafluorophosphate are added to the electrolyte in a mass ratio of 4:6, the mass proportion of FEC is 30%, and the sum of the mass of lithium bistrifluoromethanesulfonyl imide and the concentration of lithium hexafluorophosphate is 1.01 mol / L. The liquid electrolyte is added to a bare battery cell, which is vacuum sealed and subjected to high-temperature curing, followed by chemical formation and volume separation to prepare an in-situ cured battery cell.

[0117] The preparation method of the composite porous membrane in Example 2 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 68%:17%:13%:2%.

[0118] The preparation method of the composite porous membrane in Example 3 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 68.85%:16.15%:13%:2%.

[0119] The preparation method of the composite porous membrane in Example 4 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 72.25%:12.75%:13%:2%.

[0120] The preparation method of the composite porous membrane in Examples 5 to 8 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 68%:17%:13%:2%.

[0121] The preparation method of the composite porous membrane in Example 9 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 68%:17%:8%:5%.

[0122] The preparation method of the composite porous membrane in Example 10 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 66%:19%:11%:4%.

[0123] The preparation method of the composite porous membrane in Example 11 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 66%:19%:14.1%:0.9%.

[0124] The preparation method of the composite porous membrane in Example 12 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 66%:19%:14.5%:0.5%.

[0125] The preparation method of the composite porous membrane in Comparative Example 2 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 59.5%:25.5%:13%:2%.

[0126] The preparation method of the composite porous membrane in Comparative Example 3 is the same as that in Example 1, except that, based on the total mass of the glue, the mass ratio of the organic polymer, the inorganic electrolyte, the pore former and the plasticizer is 76.5%:8.5%:13%:2%.

[0127] Table 1

[0128] Performance Testing

[0129] 1. Power performance test method

[0130] The stacked three-electrode test method uses a three-electrode cell with a copper wire as the reference electrode. At 25°C, the lithium deposition charge rate of the stacked cell is tested at each SOC. The maximum charge rate is terminated when the reference electrode potential drops to 0mV, and the maximum charge rate at this SOC is recorded. According to this method, with 5% SOC as a point, the maximum charge rate at each 5% SOC is tested, such as 20% SOC, 25% SOC, 30% SOC to 100% SOC. The continuous charging time at 20% SOC-80% SOC is calculated according to the maximum charge rate at 20% SOC-80% SOC obtained from this test, which is the fast charging time.

[0131] 2. Battery capacity

[0132] The battery cell prepared above was allowed to rest at 25°C for 2 hours to ensure the cell temperature was 25°C. At 25°C, the battery cell was charged at 0.1C to a charge cutoff voltage of 4.25V. Constant voltage charging was then continued at this charge cutoff voltage until the current reached 0.02C, at which point charging was terminated (where C represents the rated capacity of the battery cell). The battery cell was allowed to rest at 25°C for 0.5 hours. At 25°C, the battery cell was discharged at 0.1C to a discharge cutoff voltage of 2.7V. The total discharge capacity (C0) of the battery cell was recorded.

[0133] The test results of the batteries in Examples 1 to 12 and Comparative Examples 1 to 3 are shown in Table 2.

[0134] Table 2

[0135] Conclusion: Comparison of Examples 1-12 with Comparative Example 1 demonstrates that, by providing a composite porous membrane within a semi-solid-state battery, the present application improves the ionic conductivity of the composite porous membrane, thereby increasing the lithium ion transport rate through the composite porous membrane and improving the battery's power performance, compared to forming a separator membrane via in situ polymerization. The presence of pores of varying sizes within the composite porous membrane increases the number of lithium ions migrating across the composite porous membrane, thereby enhancing the battery's capacity.

[0136] It can be seen from the comparison between Examples 1 to 12 and Comparative Examples 2 and 3 that by making the ionic conductivity of the composite porous membrane -4 S / cm-5×10 -4 S / cm range, the transmission rate of the composite porous membrane to lithium ions can be improved, the power performance of the battery can be improved, and the battery capacity can be improved.

[0137] It can be seen from Examples 1 to 4 that by adjusting the content of organic polymer and inorganic electrolyte on the composite porous membrane, the ionic conductivity of the composite porous membrane can be adjusted, thereby increasing the transmission rate of lithium ions through the composite porous membrane, improving the power performance of the battery, and improving the battery capacity.

[0138] It can be seen from Examples 5 to 8 that by adjusting the thickness of the composite porous membrane, multidimensional channels can be provided for the transmission of lithium ions, thereby increasing the transmission rate of the composite porous membrane to lithium ions, improving the power performance of the battery, and improving the battery capacity.

[0139] It can be seen from Examples 9 to 12 that by adjusting the porosity of the composite porous membrane, the ionic conductivity of the composite porous membrane can be adjusted, thereby increasing the composite porous membrane's lithium ion transmission rate, improving the battery's power performance, and improving the battery's capacity.

[0140] Figures 7 and 8 are SEM images of the composite porous membrane in Example 2. It can be seen from the figures that the composite porous membrane has pores of different pore sizes, which can increase the transmission rate of lithium ions and improve the power performance of the battery; it can also reduce the resistance to lithium ion transmission during charging and discharging, increase the number of lithium ion migration, and thus improve the battery capacity.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A composite porous membrane, wherein The composite porous membrane comprises an organic polymer substrate and an inorganic electrolyte, wherein the inorganic electrolyte is dispersed in the organic polymer substrate, and a plurality of pores with different pore sizes are formed on the composite porous membrane, and the ionic conductivity of the composite porous membrane is 1×10 -4 S / cm-5×10 -4 S / cm.

2. The composite porous membrane according to claim 1, wherein The ionic conductivity of the composite porous membrane is 2×10 -4 S / cm-5×10 -4 S / cm.

3. The composite porous membrane according to claim 1 or 2, wherein The ratio of the mass of the organic polymer substrate to the mass of the inorganic electrolyte is 3-5.

67.

4. The composite porous membrane according to any one of claims 1 to 3, wherein One or more of the following conditions are met: Based on the total mass of the composite porous membrane, the mass proportion of the organic polymer is 75%-85%; Based on the total mass of the composite porous membrane, the mass proportion of the inorganic electrolyte is 15%-25%.

5. The composite porous membrane according to any one of claims 1 to 4, wherein One or more of the following conditions are met: The organic polymer substrate includes one or more of polyvinylidene fluoride, polyhexafluoropropylene, polyvinyl chloride, polyacrylonitrile, polystyrene, polyvinyl acetate, polymethyl methacrylate, and polyethylene dimethacrylate; The inorganic electrolyte includes one or more of silicon dioxide, aluminum oxide, lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, and lithium aluminum germanium phosphide.

6. The composite porous membrane according to any one of claims 1 to 5, wherein The pores have a pore diameter ranging from 0.5 nm to 5 μm.

7. The composite porous membrane according to any one of claims 1 to 6, wherein The porosity of the composite porous membrane is 40%-70%.

8. The composite porous membrane according to any one of claims 1 to 7, wherein The thickness of the composite porous membrane is 8 μm-20 μm.

9. A method for preparing the composite porous membrane according to any one of claims 1 to 8, wherein: include: An organic polymer and an inorganic electrolyte are mixed and heated to form a membrane, and the membrane is pore-formed to form a composite porous membrane having a plurality of pores of different pore sizes, wherein the ionic conductivity of the composite porous membrane is 1×10 -4 S / cm-5×10 -4 S / cm.

10. The method according to claim 9, wherein: The organic polymer, the inorganic electrolyte and the pore-forming agent are mixed, heated and dried to form the composite porous membrane.

11. The method according to claim 9 or 10, wherein: The ratio of the mass of the organic polymer to the mass of the inorganic electrolyte is 3-5.

67.

12. A battery, wherein: The invention comprises the composite porous membrane according to any one of claims 1 to 8 or the composite porous membrane prepared by the method according to any one of claims 9 to 11.

13. The battery according to claim 12, wherein The battery comprises a semi-solid state battery.

14. An electrical device, wherein: A battery comprising the battery according to claim 12 or 13.

Images