Lithium battery and electronic device

Abstract

The present application provides a lithium battery comprising a positive electrode, a negative electrode, and a separator and electrolyte located between the positive and negative electrodes. The separator comprises lithiated aluminum silicate zeolite, and the lithium content of the separator is 0.1 mol / L to 50 mol / L. The concentration of lithium ions in the electrolyte is less than or equal to 0.15 mol / L. The lithium battery utilizes a specific separator-electrolyte system to enable uniform lithium ion transmission between the positive and negative electrodes, thereby suppressing the growth of lithium dendrites and enabling the lithium battery to have high energy density, high safety, and good cycle performance. The present application also provides an electronic device.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a lithium battery and an electronic device. Background Art

[0002] As a high-energy, green secondary battery, lithium-ion batteries have the characteristics of high energy density, high specific power, good cycle performance, no memory effect, and no pollution. They have been widely used in new energy fields such as smart mobile devices, hybrid vehicles, electric vehicles, and solar power generation systems. Lithium-ion batteries are mainly composed of four parts: positive and negative electrode materials, electrolyte, separator, and battery casing. Among them, the metallic lithium negative electrode has a high theoretical specific capacity and can greatly improve the energy density of lithium-ion batteries. However, the metallic lithium negative electrode is prone to the formation of lithium dendrites during use. The growth of lithium dendrites will destroy the SEI film of the negative electrode, resulting in an increase in the volume of the negative electrode, a decrease in the capacity and coulombic efficiency of the battery, and lithium dendrites may even pierce the separator, causing the battery to short-circuit, leading to serious safety issues. Therefore, it is necessary to improve lithium-ion batteries to inhibit the growth of lithium dendrites and obtain lithium batteries with high energy density, high safety, and good cycle performance. Summary of the Invention

[0003] In view of this, the present application provides a lithium battery that adopts a specific diaphragm electrolyte system to enable lithium ions to be evenly transmitted between the positive and negative electrodes, thereby inhibiting the growth of lithium dendrites, so that the lithium battery can have high energy density, high safety and good cycle performance.

[0004] In a first aspect, the present application provides a lithium battery, comprising a positive electrode sheet, a negative electrode sheet, and a diaphragm and an electrolyte located between the positive electrode sheet and the negative electrode sheet, wherein the diaphragm comprises lithiated aluminum silicate zeolite, and the content of lithium element in the diaphragm is 0.1 mol / L to 50 mol / L; the concentration of lithium ions in the electrolyte is less than or equal to 0.15 mol / L.

[0005] In the lithium battery separator of the present application, the lithiated aluminum silicate zeolite contains a large amount of coordinated lithium ions, which can be solvated in the electrolyte, thereby having a certain lithium ion transmission capacity, and the lithiated aluminum silicate zeolite has a strong adsorption force on the lithium salt in the electrolyte, so that most of the lithium salt in the electrolyte is adsorbed in the separator. The content of lithium elements in the separator includes the coordinated lithium ions in the lithiated aluminum silicate zeolite and the lithium ions in the adsorbed lithium salt. The coordinated lithium ions and the lithium ions in the adsorbed lithium salt give the separator good lithium ion transmission performance; the concentration of lithium ions in the electrolyte is less than or equal to 0.15 mol / L, and the concentration of free anions in the electrolyte is also low, thereby alleviating the spatial electric field problem caused by the uneven distribution of free anions, allowing lithium ions to be evenly deposited on the surface of the metal lithium negative electrode, and inhibiting the formation of lithium dendrites.

[0006] Optionally, the molar ratio of lithium ions in the electrolyte to lithium elements in the separator is 1:(10-500000).

[0007] Optionally, the diaphragm is adsorbed with lithium salt, the ratio of the mass of the lithium salt to the average pore volume of the diaphragm is less than or equal to 1 / 7, and the m 锂 The unit is g, the V 隔 The unit is cm 3 .

[0008] Optionally, the concentration of lithium ions in the electrolyte is greater than or equal to 0.0001 mol / L.

[0009] Optionally, in the diaphragm, the mass percentage of the lithiated aluminum silicate zeolite is 80% to 99%.

[0010] Optionally, the average pore diameter of the lithiated aluminosilicate zeolite is 0.1 nm to 20 nm.

[0011] Optionally, the average particle size of the lithiated aluminosilicate zeolite is 10 nm to 2000 nm.

[0012] Optionally, the average specific surface area of ​​the lithiated aluminum silicate is 1 m 2 / g~800m 2 / g.

[0013] Optionally, the lithiated aluminosilicate zeolite comprises at least two lithiated aluminosilicate zeolites with different particle size ranges.

[0014] Optionally, the lithiated aluminum silicate zeolite includes two lithiated aluminum silicate zeolites of different particle size ranges in the following mass ratio:

[0015] Lithiated aluminosilicate zeolite with a particle size of 30 nm to 50 nm: 20%-60%;

[0016] Lithiated aluminum silicate zeolite with a particle size of 200nm to 300nm: 40%-80%.

[0017] Optionally, the polymer includes one or more of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, sodium alginate, aramid, polyacrylonitrile and polyacrylic acid.

[0018] Optionally, in the diaphragm, the mass percentage of the polymer is 1% to 20%.

[0019] Optionally, the thickness of the diaphragm is 1 μm to 100 μm.

[0020] Optionally, the porosity of the diaphragm is 10% to 60%.

[0021] Optionally, the negative electrode sheet includes a metal lithium sheet, and the positive electrode sheet includes a metal lithium sheet.

[0022] Optionally, the electrolyte includes a solution of an electrolyte lithium salt in a solvent, and the solvent includes one or more of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, methylpropyl carbonate, dipropyl carbonate and vinylene carbonate.

[0023] In a second aspect, the present application provides an electronic device, which includes the lithium battery described in the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic structural diagram of a lithium battery provided in one embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] Lithium-ion batteries are widely used in the field of mobile power sources. Nowadays, people have increasingly higher requirements for the energy density of mobile power sources. Metallic lithium has a high theoretical specific capacity. Using metallic lithium as the negative electrode can greatly improve the energy density of lithium-ion batteries. However, the negative electrode of metallic lithium has a serious problem of dendrite growth during use. The hazards of lithium dendrites are mainly in three aspects: first, they can puncture the diaphragm and cause a short circuit, leading to serious safety accidents; second, lithium dendrites can undergo in-situ chemical reactions with the electrolyte to form an electronic insulating film on the surface. This film will cause mutual electronic insulation between lithium dendrites. Once the root is broken, the entire lithium dendrite loses its electrochemical activity, resulting in a rapid decrease in battery capacity; third, the spatial volume of lithium dendrites is large, which can easily cause battery volume expansion and battery cycle performance degradation.

[0027] Currently, there are several methods to inhibit the growth of lithium dendrites: (1) forming an artificial SEI film on the surface of the metallic lithium negative electrode to regulate the deposition of lithium ions and inhibit the growth of lithium dendrites; (2) alloying metallic lithium with other metals to form a complex metallic lithium negative electrode, regulating the spatial electric field on the negative electrode surface, and inhibiting the growth of lithium dendrites; (3) setting a barrier layer on the surface of the metallic lithium negative electrode to prevent lithium dendrites from piercing; (4) adding additives to the electrolyte to utilize the ion shielding effect to inhibit the growth of lithium dendrites; (5) using a three-dimensional current collector to regulate the spatial electric field on the current collector surface and inhibit the growth of lithium dendrites; (6) using a solid or semi-solid electrolyte to reduce the spatial electric field caused by the uneven distribution of lithium ions on the negative electrode surface and inhibit the growth of lithium dendrites. However, the above methods still have certain defects. Specifically, for method (1), due to the brittle texture of the artificial SEI film, the artificial SEI film will deform and then break after the battery is repeatedly charged and discharged for a long time, which cannot effectively solve the problem of lithium dendrite growth; for method (2), the overall specific capacity of the complex metal lithium negative electrode is low, which is not conducive to the preparation of high specific energy batteries; for method (3), setting a barrier layer on the surface of the metal lithium negative electrode will increase the proportion of inactive substances in the battery and the thickness of the battery, which is also not conducive to the preparation of high specific energy batteries; for method (4), the electrolyte additive only works on charging and discharging at low current density, which limits the application of the battery; for method (5), when the three-dimensional current collector is filled with lithium, it cannot inhibit the growth of lithium dendrites, which is not conducive to the preparation of high surface capacity batteries; for method (6), when using solid or semi-solid electrolytes, the contact between the electrolyte and the lithium negative electrode is poor, which is not conducive to the transmission of lithium ions, and because the electrolyte material is brittle, it is also not conducive to production and use. Therefore, it is necessary to develop a new method to inhibit the growth of lithium dendrites to obtain lithium batteries with high energy density, high safety and good cycle performance.

[0028] In order to improve the electrochemical performance and safety performance of the battery, this application designs a new diaphragm electrolyte system. The lithium battery using this diaphragm electrolyte system not only has a high energy density and is not prone to the formation of lithium dendrites, but also has good cycle performance and safety performance. Figure 1 , Figure 1 This is a schematic diagram of the structure of a lithium battery provided in one embodiment of the present application. The lithium battery includes a positive electrode sheet 10, a negative electrode sheet 20, a separator 30, and an electrolyte 40. In the embodiment of the present application, the separator includes lithiated aluminum silicate zeolite, wherein the lithiated aluminum silicate zeolite is obtained by lithium ion exchange, and the lithium ions form coordination bonds with the aluminum silicon oxide anion skeleton. The chemical formula of the lithiated aluminum silicate zeolite is (SiO2) x (LiAlO2) y , wherein x:y is 100:1 to 1:2. In some embodiments of the present application, the aluminosilicate zeolite subjected to lithium ion exchange comprises one or more of X-type zeolite, A-type zeolite and Y-type zeolite.

[0029] In the present application, the coordinated lithium ions in the lithiated aluminum silicate zeolite can react with the electrolyte to undergo solvation, thereby realizing the transmission of lithium ions in the diaphragm, and the lithiated aluminum silicate zeolite will also adsorb lithium salts in the electrolyte. On the one hand, the adsorbed lithium salts increase the number of lithium ions in the diaphragm, greatly improving the rate of lithium ion transmission by the diaphragm; on the other hand, the lithium salt concentration in the electrolyte is reduced, and the number of free ions is reduced, thereby alleviating the spatial electric field problem caused by the uneven distribution of free ions, allowing lithium ions to be evenly deposited on the surface of the metal lithium negative electrode, and inhibiting the formation of lithium dendrites.

[0030] In the embodiment of the present application, the content of lithium in the diaphragm is 0.1 mol / L to 50 mol / L. The content of lithium in the diaphragm refers to the molar amount of lithium per unit volume of the diaphragm. The lithium in the diaphragm includes the coordinated lithium ions in the lithiated aluminum silicate zeolite and the lithium ions of the lithium salt adsorbed in the diaphragm. The content of lithium in the diaphragm can be, but is not limited to, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 5 mol / L, 10 mol / L, 30 mol / L or 50 mol / L. In the present application, after the diaphragm adsorbs the lithium salt, the lithium ions in the diaphragm electrolyte system are concentrated at the diaphragm. The lithium ions will be solvated under the action of the electrolyte, so that the lithium ions can be transported in the diaphragm. The diaphragm electrolyte system realizes the transmission of lithium ions through a solid ion transport mechanism, and its principle is similar to that of a solid electrolyte. Moreover, in the diaphragm electrolyte system of the present application, the adsorption of lithium salt by the diaphragm is non-rigid, and the lithium ions in the adsorbed lithium salt still have a certain delocalization ability in the diaphragm and can be separated from the diaphragm by a certain distance. The solvent in the electrolyte can improve the ability of lithium ions to transmit across boundaries and reduce the transmission resistance of lithium ions at the interface between the diaphragm and the electrode. Therefore, compared with solid electrolytes, it has good lithium ion transmission capacity.

[0031] In some embodiments of the present application, the mass m of the lithium salt adsorbed by the diaphragm is 锂 The average pore volume V of the diaphragm 隔 The ratio is less than or equal to 1 / 7, where m 锂 The unit is g, V 隔 The unit is cm 3 The mass of lithium salt adsorbed by the diaphragm is m 锂 The average pore volume V of the diaphragm 隔 The ratio of can be, but is not limited to, 1:7, 1:50, 1:100, 1:500, 1:1000, 1:10000 or 1:100000. 锂 / V 隔 When the value of is less than or equal to 1 / 7, the lithium salt is distributed more evenly in the diaphragm and the lithium ion transfer rate is faster. In some embodiments of the present application, the mass m of the lithium salt adsorbed by the diaphragm is 锂 The average pore volume V of the diaphragm 隔The ratio is 1 / 19 to 1 / 12. For the same pore volume of the diaphragm, the mass of the lithium salt is adjusted so that the mass of the lithium salt m 锂 The average pore volume V of the diaphragm 隔 When the ratio is within the above range, the separator can have good lithium ion transport performance, and the battery is less likely to produce lithium dendrites, thereby improving the cycle performance of the battery.

[0032] In the embodiment of the present application, when the concentration of lithium ions in the electrolyte is less than or equal to 0.15 mol / L, the formation of lithium dendrites can be effectively suppressed. If the concentration of lithium ions in the electrolyte is greater than 0.15 mol / L, the lithium ions will be deposited to form lithium dendrites due to uneven distribution and excessive local concentration, and the battery performance will be reduced. In the present application, the concentration of lithium ions in the electrolyte refers to the concentration of lithium ions in the electrolyte when the diaphragm and the electrolyte reach adsorption equilibrium. Specifically, in the preparation process of the lithium battery, the lithium salt is first dissolved in the solvent to form a first electrolyte. After the first electrolyte and the diaphragm are assembled, the diaphragm will adsorb the lithium salt in the first electrolyte, so that the lithium salt concentration of the electrolyte is reduced to form a second electrolyte. The concentration of lithium ions in the second electrolyte is the concentration of lithium ions in the electrolyte when the diaphragm and the electrolyte reach adsorption equilibrium, that is, the concentration of lithium ions in the second electrolyte is less than or equal to 0.15 mol / L. In some embodiments of the present application, the concentration of lithium ions in the electrolyte is less than or equal to 0.01 mol / L. When the concentration of lithium ions in the electrolyte is low, the lithium ions are basically transmitted along the transmission path of the diaphragm, thereby improving the uniformity of the distribution of lithium ions on the negative electrode surface, and alleviating the tip effect caused by the uneven spatial electric field, and inhibiting the growth of lithium dendrites. In some embodiments of the present application, the concentration of lithium ions in the electrolyte is 0.0001 mol / L to 0.15 mol / L. The concentration of lithium ions in the electrolyte can be, but is not limited to, 0.0001 mol / L, 0.001 mol / L, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L or 0.15 mol / L. When the concentration of lithium ions in the electrolyte is greater than or equal to 0.0001 mol / L, the electrolyte can increase the conductivity of the system and improve the electrochemical performance of the lithium battery.

[0033] In the embodiment of the present application, the molar ratio of lithium ions in the electrolyte to lithium elements in the separator is 1:10 to 1:500000. The molar ratio of lithium ions in the electrolyte to lithium elements in the separator can be, but is not limited to, 1:10, 1:100, 1:1000, 1:10000, 1:100000, or 1:500000.

[0034] In an embodiment of the present application, the lithiated aluminum silicate is in granular form, and the average particle size of the lithiated aluminum silicate is 10 nm to 2000 nm. In some embodiments of the present application, the average particle size of the lithiated aluminum silicate is 20 nm to 1000 nm. The average particle size of the lithiated aluminum silicate can be, but is not limited to, 10 nm, 20 nm, 50 nm, 100 nm, 200 nm, 400 nm, 500 nm, 800 nm, 1000 nm, or 2000 nm. In some embodiments of the present application, the lithiated aluminum silicate zeolite includes at least two lithiated aluminum silicate zeolites of different particle size ranges, for example, the lithiated aluminum silicate zeolite includes a first lithiated aluminum silicate zeolite with an average particle size of 10 nm to 100 nm and a second lithiated aluminum silicate zeolite with an average particle size of 400 nm to 600 nm, or the lithiated aluminum silicate zeolite includes a first lithiated aluminum silicate zeolite with an average particle size of 10 nm to 80 nm, a second lithiated aluminum silicate zeolite with an average particle size of 200 nm to 400 nm and a third lithiated aluminum silicate zeolite with an average particle size of 800 nm to 1000 nm. The use of lithiated aluminum silicate zeolite in different particle size ranges is conducive to the formation of a higher density and uniformity of the diaphragm. The diaphragm per unit area can adsorb more lithium salts, making the lithium salt concentration in the electrolyte lower, reducing the interference of the electrolyte, promoting the transmission of lithium ions along the transmission channel of the lithiated aluminum silicate zeolite, and alleviating the uneven distribution of ions that causes the growth of lithium dendrites. At the same time, the higher uniformity of the diaphragm can promote the uniform transmission and deposition of lithium ions, and improve the space utilization of the lithium negative electrode. In some embodiments of the present application, the lithiated aluminum silicate zeolite includes a first lithiated aluminum silicate zeolite with an average particle size of 30nm to 50nm and a second lithiated aluminum silicate zeolite with an average particle size of 200nm to 300nm, wherein the mass percentage of the first lithiated aluminum silicate zeolite is 20% to 70% of the lithiated aluminum silicate zeolite, and the mass percentage of the second lithiated aluminum silicate zeolite is 30% to 80% of the lithiated aluminum silicate zeolite. The diaphragm prepared using the lithiated aluminum silicate zeolite with the above ratio not only has high density and good uniformity, but also has a large adsorption capacity for lithium salts, thereby effectively controlling the concentration of lithium ions in the electrolyte and inhibiting the formation of lithium dendrites.

[0035] In the present application, the lithiated aluminum silicate zeolite has a porous structure, and the average pore size of the lithiated aluminum silicate zeolite is 0.1nm to 20nm. In some embodiments of the present application, the average pore size of the lithiated aluminum silicate zeolite is 0.5nm to 1.5nm. The average pore size of the lithiated aluminum silicate zeolite can be, but is not limited to, 0.1nm, 0.5nm, 1nm, 5nm, 10nm, 15nm or 20nm. In the embodiments of the present application, the average specific surface area of ​​the lithiated aluminum silicate zeolite is 1m 2 / g~800m 2 / g, in some embodiments of the present application, the specific surface area of ​​the lithiated aluminum silicate is 100m 2 / g~800m 2 / g, the specific surface area of ​​lithiated aluminum silicate can be, but is not limited to, 1m2 / g、5m 2 / g、10m 2 / g, 20m 2 / g, 50m 2 / g、100m 2 / g, 200m 2 / g, 400m 2 / g or 800m 2 The larger the specific surface area of ​​lithiated aluminum silicate, the more lithium ion transmission paths there are, which is more conducive to the transmission of lithium ions.

[0036] In some embodiments of the present application, the mass percentage of the lithiated aluminum silicate zeolite in the separator is 80% to 99%. The mass percentage of the lithiated aluminum silicate zeolite in the separator can be, but is not limited to, 80%, 85%, 88%, 90%, 93%, 95%, 97%, or 99%. Controlling the content of the lithiated aluminum silicate zeolite can ensure that the separator fully absorbs the lithium salt in the electrolyte, thereby reducing the concentration of lithium ions in the electrolyte and inhibiting the formation of lithium dendrites.

[0037] In some embodiments of the present application, the diaphragm includes a polymer and lithiated aluminum silicate, and the polymer is used to bond the lithiated aluminum silicate to form a diaphragm. In the embodiments of the present application, the polymer includes one or more of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, sodium alginate, aramid, polyacrylonitrile, and polyacrylic acid. In some embodiments of the present application, the polymer is polytetrafluoroethylene. Polytetrafluoroethylene has good bonding properties, which can reduce the amount of polymer used, thereby reducing the resistance to lithium ion transmission. In addition, polytetrafluoroethylene has good wettability to the electrolyte. The use of polytetrafluoroethylene is beneficial to improving the stability of the diaphragm during high-rate charge and discharge and the rate performance of the battery. In the embodiments of the present application, the mass percentage of the polymer in the diaphragm is 1% to 20%. The mass percentage of the polymer in the diaphragm can be, but is not limited to, 1%, 3%, 5%, 7%, 10%, 12%, or 20%. In some embodiments of the present application, the mass ratio of the polymer to the lithiated aluminum silicate is 1:(20-99), and the mass ratio of the polymer to the lithiated aluminum silicate can be, but is not limited to, 1:20, 1:40, 1:50, 1:70, or 1:90. Controlling the mass ratio of the polymer to the lithiated aluminum silicate can ensure that the separator has both good structural stability and a high lithium ion content.

[0038] In some embodiments of the present application, the thickness of the diaphragm is 1 μm to 100 μm. In some embodiments of the present application, the thickness of the diaphragm is 1 μm to 30 μm. The thickness of the diaphragm can be, but is not limited to, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 50 μm, 80 μm or 100 μm. Controlling the thickness of the diaphragm can adjust the proportion of inactive substances in the battery, so that the lithium battery has a higher energy density. In some embodiments of the present application, the porosity of the diaphragm is 10% to 60%. The porosity of the diaphragm can be, but is not limited to, 10%, 20%, 30%, 40% or 60%.

[0039] In the embodiment of the present application, the electrolyte of the lithium battery includes an electrolyte lithium salt and a solvent. In the embodiment of the present application, the solvent includes one or more of a chain acid ester and a cyclic acid ester. The chain acid ester includes one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and dipropyl carbonate (DPC), and the cyclic acid ester includes one or more of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), γ-butyrolactone (γ-BL) and sultone. In some embodiments of the present application, the solvent includes one or more of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, dipropyl carbonate and vinylene carbonate. The above solvents can promote the solvation of lithium ions, thereby enhancing the ability of the diaphragm to transport lithium ions. In some embodiments of the present application, the electrolyte lithium salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorosilicate (LiSiF6), lithium tetraphenylborate (LiB(C6H5)4), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate (LiAlCl4), lithium fluoroalkylsulfonate (LiC(SO2CF3)3), LiCH3SO3, LiN(SO2CF3)2 and LiN(SO2C2F5)2.

[0040] In the embodiment of the present application, the positive electrode sheet of the lithium battery includes a positive electrode active material that can reversibly insert / deinsert lithium ions. The positive electrode sheet of the lithium battery in the present application can be any positive electrode known in the art. Specifically, the positive electrode active material can be, but is not limited to, lithium cobalt oxide (LiCoO2), lithium iron phosphate (LiFePO4), LiNi 0.33 Co 0.33 Mn 0.33 O2(NCM111), LiNi 0.4 Co 0.2 Mn 0.4 O2(NCM424), LiNi 0.5 Co 0.2 Mn0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622),LiNi 0.8 Co 0.1 Mn 0.1 In some embodiments of the present application, the negative electrode of the lithium battery includes one or more of a carbon-based negative electrode, a silicon-based negative electrode, and a lithium negative electrode. In some embodiments of the present application, the negative electrode of the lithium battery includes a metallic lithium sheet. When metallic lithium is used as the negative electrode, the energy density of the lithium battery can be greatly improved.

[0041] This application uses a specific diaphragm and a certain concentration of electrolyte to form a new diaphragm electrolyte system. The diaphragm electrolyte system has good interfacial ion transmission characteristics. Lithium ions can be evenly transmitted between the positive and negative electrodes along the transmission channel of the diaphragm, which can inhibit lithium ion aggregation, alleviate the tip effect caused by spatial electric field unevenness, reduce the formation of lithium dendrites, and make the lithium battery have high safety and good cycle performance. The diaphragm electrolyte system has both the characteristics of a solid electrolyte single ion conductor, which can effectively inhibit the growth of lithium dendrites, and the ability of a liquid electrolyte to transmit lithium ions across the boundary, ensuring that the overall lithium ion transmission rate is high.

[0042] The present application also provides a method for preparing the above-mentioned lithium battery, comprising the following steps:

[0043] Step 100: mixing lithiated aluminosilicate zeolite with a polymer and pressing and molding the mixture to obtain a diaphragm;

[0044] Step 200: Assemble the separator, the positive electrode sheet, and the negative electrode sheet to form a battery cell, place the battery cell in a battery casing, inject electrolyte, and seal the battery casing to obtain a lithium battery.

[0045] In some embodiments of the present application, the preparation method of lithiated aluminum silicate zeolite comprises: soaking aluminum silicate zeolite in a solution containing lithium ions, washing and drying to obtain lithiated aluminum silicate zeolite, wherein the solution containing lithium ions can be a lithium hydroxide solution or a lithium salt solution, and the lithium salt solution includes one or more of lithium chloride, lithium perchlorate, lithium oxalate and lithium acetate, and the concentration of the solution containing lithium ions is 0.1 mol / L to 5 mol / L. In some embodiments of the present application, the preparation method of lithiated aluminum silicate zeolite comprises: soaking aluminum silicate zeolite in a lithium hydroxide solution with a concentration of 0.5 mol / L to 3 mol / L for 5 h to 20 h, filtering and washing, and then soaking in a lithium hydroxide solution with a concentration of 0.5 mol / L to 3 mol / L for 3 h to 20 h, repeating the operation until the concentration of lithium hydroxide remains substantially unchanged, thereby obtaining lithiated aluminum silicate zeolite. In some embodiments of the present application, the lithiated aluminum silicate zeolite and the polymer are uniformly mixed by supersonic stirring or ultrasonic method, and the diaphragm is obtained by extrusion molding.

[0046] In step 200 of the present application, after the electrolyte is injected, the diaphragm will adsorb the lithium salt in the electrolyte, thereby reducing the concentration of lithium ions in the electrolyte. In some embodiments of the present application, when preparing the electrolyte, the lithium ion concentration in the electrolyte is 0.001mol / L to 0.4mol / L, and the initial lithium ion concentration of the electrolyte can be, but is not limited to, 0.001mol / L, 0.005mol / L, 0.01mol / L, 0.05mol / L, 0.1mol / L, 0.2mol / L or 0.4mol / L. In some embodiments of the present application, the ratio of the mass of the lithium salt injected into the electrolyte to the mass of the diaphragm is 1:(3.3×10 -4 ~0.132).

[0047] The preparation method of the lithium battery provided in the present application is simple to operate, and the prepared lithium battery has high safety and good cycle performance, which is conducive to the application of lithium batteries.

[0048] The present application also provides an electronic device comprising the above-mentioned lithium battery.

[0049] The technical solution of this application is further described below with reference to a number of embodiments.

[0050] Example 1

[0051] A method for preparing a lithium battery, comprising:

[0052] 1) Preparation of diaphragm

[0053] Aluminum silicate zeolite was prepared by hydrothermal method. The obtained aluminum silicate was Na-X zeolite. The Na-X zeolite was soaked in 1 mol / L lithium hydroxide aqueous solution for 12 hours, filtered and washed, and then soaked in 1 mol / L lithium hydroxide aqueous solution for 12 hours. The operation was repeated three times. After washing and drying, Li-X zeolite was obtained, i.e., lithiated aluminum silicate zeolite. The obtained lithiated aluminum silicate zeolite had an average pore diameter of 3 nm, an average particle size of 250 nm, and an average specific surface area of ​​450 m 2 / g; average pore volume is 0.5cm 3 / g;

[0054] Lithiated aluminum silicate and polytetrafluoroethylene (PFTE) were mixed in a mass ratio of 95:5, and after supersonic stirring for 30 minutes, the mixture was extruded into a film with a thickness of 10 μm. The obtained film was a diaphragm, and the porosity of the diaphragm was 55%.

[0055] 2) Battery assembly

[0056] The diaphragm was cut into discs with a diameter of 14 mm, and metal lithium sheets were used as the positive and negative electrodes of the battery. The diameter of the metal lithium sheet was 10 mm and the thickness was 300 μm. The diaphragm and the metal lithium sheet were assembled into a lithium-to-lithium symmetrical button battery, into which 80 μL of electrolyte was injected. The lithium salt in the electrolyte was LiPF6, and the concentration of the lithium salt was 0.001 mol / L. The solvent of the electrolyte was a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (the volume ratio of EC and DMC was 1:1). A lithium battery was obtained. The lithium battery of Example 1 is recorded as S1.

[0057] Example 2

[0058] The difference between Example 2 and Example 1 is that when assembling the battery in Example 2, the concentration of lithium salt LiPF6 in the electrolyte used is 0.1 mol / L. The lithium battery in Example 2 is recorded as S2.

[0059] Example 3

[0060] The difference between Example 3 and Example 1 is that when assembling the battery in Example 3, the concentration of lithium salt LiPF6 in the electrolyte used is 0.15 mol / L. The lithium battery in Example 3 is recorded as S3.

[0061] Example 4

[0062] The difference between Example 4 and Example 1 is that when assembling the battery in Example 4, the concentration of lithium salt LiPF6 in the electrolyte used is 0.2 mol / L. The lithium battery in Example 4 is recorded as S4.

[0063] Example 5

[0064] The difference between Example 5 and Example 1 is that when assembling the battery in Example 5, the concentration of lithium salt LiPF6 in the electrolyte used is 0.3 mol / L. The lithium battery of Example 5 is recorded as S5.

[0065] Example 6

[0066] The difference between Example 6 and Example 1 is that when assembling the battery in Example 6, the concentration of lithium salt LiPF6 in the electrolyte used is 0.399 mol / L. The lithium battery of Example 6 is recorded as S6.

[0067] Example 7

[0068] The difference between Example 7 and Example 1 is that in Example 7, two lithiated aluminum silicate zeolites with different particle sizes are used in preparing the diaphragm, wherein the first lithiated aluminum silicate zeolite has an average pore size of 3 nm and an average particle size of 250 nm; and an average specific surface area of ​​450 m 2 / g; average pore volume is 0.5cm 3 / g; the average pore size of the second lithiated aluminum silicate is 3nm, the average particle size is 40nm; the average specific surface area is 550m 2 / g; average pore volume is 0.4cm 3 / g.

[0069] The lithiated aluminum silicate zeolites of two particle size ranges were mixed in a mass ratio of 1:1, and then the lithiated aluminum silicate zeolite and polytetrafluoroethylene (PFTE) were mixed in a mass ratio of 95:5. After supersonic stirring for 30 minutes, the mixture was extruded into a 10 μm thick diaphragm with a porosity of 40%.

[0070] The diaphragm was cut into discs with a diameter of 14 mm, and metal lithium sheets were used as the positive and negative electrodes of the battery. The diameter of the metal lithium sheet was 10 mm and the thickness was 300 μm. The diaphragm and the metal lithium sheet were assembled into a lithium-to-lithium symmetrical button battery, into which 80 μL of electrolyte was injected. The concentration of lithium salt LiPF6 in the electrolyte was 0.15 mol / L, and the solvent of the electrolyte was a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (the volume ratio of EC and DMC was 1:1). A lithium battery was obtained, and the lithium battery of Example 7 was recorded as S7.

[0071] Example 8

[0072] The difference between Example 8 and Example 3 is that, when preparing the diaphragm in Example 8, the lithiated aluminum silicate zeolite used has an average pore size of 3 nm, an average particle size of 250 nm, and an average specific surface area of ​​250 m 2 / g; average pore volume 0.2cm 3 / g; a diaphragm was prepared by the same method as in Example 1, and the porosity of the diaphragm was 55%.

[0073] A lithium battery was assembled using the same method as in Example 3. The lithium battery of Example 8 is designated as S8.

[0074] Example 9

[0075] The difference between Example 9 and Example 3 is that, in Example 9, when preparing the diaphragm, the mass ratio of lithiated aluminum silicate zeolite to polytetrafluoroethylene (PFTE) is 90:10, and after supersonic stirring for 30 minutes, the mixture is extruded into a diaphragm with a thickness of 10 μm and a porosity of 50%.

[0076] A lithium battery was assembled using the same method as in Example 3. The lithium battery of Example 9 is denoted as S9.

[0077] Example 10

[0078] The difference between Example 10 and Example 3 is that, in Example 10, when preparing the diaphragm, the mixture of lithiated aluminum silicate zeolite and polytetrafluoroethylene is extruded into a diaphragm with a thickness of 20 μm, and the porosity of the diaphragm is 55%.

[0079] A lithium battery was assembled using the same method as in Example 3. The lithium battery of Example 10 is designated as S10.

[0080] Comparative Example 1

[0081] A commercial pp film (polypropylene film) was cut into discs with a diameter of 14 mm as a diaphragm, and a metal lithium sheet was used as the positive and negative electrodes of the battery. The diameter of the metal lithium sheet was 10 mm and the thickness was 300 μm. The diaphragm and the metal lithium sheet were assembled into a lithium-to-lithium symmetrical button battery, into which 80 μL of electrolyte was injected. The lithium salt in the electrolyte was LiPF6, and the concentration of LiPF6 was 1 mol / L. The solvent of the electrolyte was a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (the volume ratio of EC and DMC was 1:1) to obtain a lithium battery. The lithium battery of Comparative Example 1 was recorded as D1.

[0082] Comparative Example 2

[0083] A diaphragm was prepared by the same method as in Example 1, and the diaphragm was cut into discs with a diameter of 14 mm. Metal lithium sheets were used as the positive and negative electrodes of the battery. The diameter of the metal lithium sheet was 10 mm and the thickness was 300 μm. The diaphragm and the metal lithium sheet were assembled into a lithium-to-lithium symmetrical button battery, into which 80 μL of electrolyte was injected. The lithium salt in the electrolyte was LiPF6, and the concentration of LiPF6 was 1 mol / L. The solvent of the electrolyte was a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (the volume ratio of EC and DMC was 1:1) to obtain a lithium battery. The lithium battery of Comparative Example 2 was recorded as D2.

[0084] Effect embodiment

[0085] In order to verify the performance of the lithium battery prepared in this application, this application provides an effect embodiment.

[0086] 1) The lithium batteries of Examples 1-10 were disassembled and the molar concentration of lithium ions in the electrolyte of the lithium batteries of each example was measured. Lithium content in the diaphragm C (隔膜，Li) And calculate the mass m of lithium salt adsorbed by the diaphragm 锂 and the pore volume V of the diaphragm 隔 The lithium ion concentration of the electrolyte is measured by inductively coupled plasma spectrometer (ICP); the lithium content in the diaphragm is measured by the following method: first use ICP to measure the lithium content M1 (mol) in the pure diaphragm, and assume that the injection volume V1 (cm 3 ) is C1 (mol / L), and the molar concentration of lithium ions in the electrolyte after adsorption is C2 (mol / L). C2 is The mass of lithium salt adsorbed by the diaphragm is (C1-C2)×V1 / 1000×M 锂盐 , the volume V (cm) of the diaphragm is calculated based on the thickness and area 3 ), then the lithium content C in the diaphragm of the added electrolyte (隔膜，Li) =(M1+(C1-C2)×V1 / 1000) / (V / 1000). Please refer to Table 1 for the test results.

[0087] Table 1 Parameters of lithium batteries of Examples 1-10

[0088]

[0089] 2) The lithium batteries of Examples 1-10 and Comparative Examples 1-3 were subjected to a cycle performance test. The test conditions were as follows: the lithium batteries of Examples 1-10 and Comparative Examples 1-2 were subjected to a cycle performance test at room temperature at a current of 1 mA / cm 2 The current was discharged at a constant current for 0.5h, and then at 1mA / cm 2 The battery was charged at a constant current of 0.5 h, and the charge and discharge capacity and voltage of the battery were recorded. After 3000 charge and discharge cycles, the cycle time when the battery short circuit occurred was recorded. For the experimental results, please refer to Table 2.

[0090] Table 2 Cycling performance of lithium batteries of Examples 1-10 and Comparative Examples 1-3

[0091]

[0092]

[0093] As can be seen from Table 1, the lithium battery provided in the present application effectively inhibits the growth of lithium dendrites due to the use of a specific diaphragm electrolyte system, thereby greatly improving the cycle performance of the battery.

[0094] The above is a preferred embodiment of the present application, but it should not be construed as limiting the scope of the present application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present application, and such improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A lithium battery comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte located between the positive electrode sheet and the negative electrode sheet, characterized in that: The diaphragm includes lithiated aluminum silicate zeolite, the content of lithium element in the diaphragm is 0.1 mol / L~50 mol / L, and the lithium element in the diaphragm includes coordinated lithium ions in the lithiated aluminum silicate zeolite and lithium ions of lithium salt adsorbed in the diaphragm; the concentration of lithium ions in the electrolyte is less than or equal to 0.15 mol / L, and the concentration of lithium ions in the electrolyte refers to the concentration of lithium ions in the electrolyte when the diaphragm and the electrolyte reach adsorption equilibrium.

2. The lithium battery according to claim 1, wherein The separator is adsorbed with lithium salt, the mass of the lithium salt is m 锂 The average pore volume V of the diaphragm 隔 The ratio is less than or equal to 1 / 7, the m 锂 The unit is g, the V 隔 The unit is cm 3 .

3. The lithium battery according to claim 1 or 2, wherein: The concentration of lithium ions in the electrolyte is greater than or equal to 0.0001 mol / L.

4. The lithium battery according to claim 1 or 2, wherein: In the diaphragm, the mass percentage of the lithiated aluminum silicate zeolite is 80% to 99%.

5. The lithium battery according to claim 1 or 2, wherein: The average pore size of the lithiated aluminum silicate is 0.1 nm to 20 nm; the average particle size of the lithiated aluminum silicate is 10 nm to 2000 nm; the average specific surface area of ​​the lithiated aluminum silicate is 1 m 2 / g~800m 2 / g.

6. The lithium battery according to claim 1 or 2, wherein: The lithiated aluminosilicate zeolite includes lithiated aluminosilicate zeolites of at least two particle size ranges.

7. The lithium battery according to claim 1 or 2, wherein: The lithiated aluminum silicate zeolite includes two types of lithiated aluminum silicate zeolites with the following mass ratios: Lithium-containing aluminum silicate zeolite with a particle size of 30 nm to 50 nm: 20% to 70%; Lithiated aluminum silicate zeolite with a particle size of 200nm~300nm: 30%~80%.

8. The lithium battery according to claim 1 or 2, wherein: The diaphragm also includes a polymer, which includes one or more of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, sodium alginate, aramid, polyacrylonitrile and polyacrylic acid; the mass percentage of the polymer in the diaphragm is 1% to 20%.

9. The lithium battery according to claim 1 or 2, wherein: The thickness of the diaphragm is 1 μm to 100 μm; the porosity of the diaphragm is 10% to 60%.

10. An electronic device, characterized in that: The electronic device comprises the lithium battery according to any one of claims 1 to 9.

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