Lithium ion battery, preparation method thereof and lithium ion battery module

Abstract

The invention discloses a lithium ion battery, a preparation method thereof and a lithium ion battery module. The lithium ion battery comprises a positive electrode, a first solid electrolyte membrane and a negative electrode which are sequentially stacked in the thickness direction, the lithium ion battery also comprises a second solid electrolyte membrane; the second solid electrolyte membrane is positioned between the positive electrode and the first solid electrolyte membrane; wherein the second solid electrolyte membrane is provided with a plurality of first through holes, and the first through holes are filled with a positive electrode lithium supplement agent. The lithium ion battery disclosed by the invention is provided with the double-layer composite solid electrolyte membrane, and the positive electrode lithium supplementing agent is filled in the through hole formed in the solid electrolyte membrane in contact with the positive electrode, so that active lithium consumed when the lithium ion battery is charged for the first time can be effectively supplemented, the total capacity and the energy density of the lithium ion battery are improved, and the cycle life of the lithium ion battery is prolonged.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a lithium-ion battery that suppresses the loss of active lithium, a method for preparing the same, and a lithium-ion battery module composed of the same lithium-ion battery. Background Technology

[0002] During the initial charging process of a lithium-ion battery, a significant and irreversible loss of lithium occurs. This leads to a reduction in the battery's capacity and energy density. Therefore, replenishing the battery with active lithium ions to offset this irreversible lithium loss is crucial for improving the battery's overall capacity and energy density. Summary of the Invention

[0003] To achieve the above objectives, this application discloses a lithium-ion battery and its preparation method, as well as a lithium-ion battery module. The lithium-ion battery includes a positive electrode lithium replenishing agent, which can replenish the active lithium lost during the first charge-discharge process due to the formation of an SEI film, thereby improving the initial coulombic efficiency, energy density, and cycle life of the lithium-ion battery.

[0004] The first aspect of this application provides a lithium-ion battery, including a positive electrode, a first solid electrolyte membrane, and a negative electrode stacked sequentially along the thickness direction; the lithium-ion battery further includes a second solid electrolyte membrane, the second solid electrolyte membrane being located between the positive electrode and the first solid electrolyte membrane; wherein the second solid electrolyte membrane has a plurality of first through holes, and the first through holes are filled with a positive electrode lithium replenishing agent.

[0005] According to some embodiments of this application, the positive electrode lithium supplement includes one or a mixture of more than one of lithium iron ferrite, lithium nickel ferrite, lithium manganese-based lithium oxide, lithium peroxide, lithium sulfide, lithium vanadium oxide, lithium nitride derivatives, and cobalt-based lithium supplements.

[0006] According to some embodiments of this application, the second solid electrolyte membrane comprises a polymer solid electrolyte with a thickness of 10 μm-20 μm.

[0007] According to some embodiments of this application, the second solid electrolyte membrane further has a plurality of second through holes, the second through holes being filled with solid electrolyte particles.

[0008] According to some embodiments of this application, the central axes of the first through hole and the second through hole are all or partly deviated from the thickness direction of the second solid electrolyte membrane, with a deviation angle of 5°-85°, and the deviation angle of the central axis of the first through hole is different from the deviation angle of the central axis of the second through hole.

[0009] According to some embodiments of this application, the first through hole and the second through hole may have the same or different diameters.

[0010] According to some embodiments of this application, the first solid electrolyte membrane includes an inorganic solid electrolyte, and the second solid electrolyte membrane includes a polymer solid electrolyte.

[0011] The second aspect of this application provides a method for preparing a lithium-ion battery, the method comprising the following steps: Step S1. Mixing an inorganic solid electrolyte with a binder and forming a film to obtain a first solid electrolyte membrane; Step S2. Coating and drying a polymer solution prepared with a polymer solid electrolyte to obtain a second solid electrolyte membrane precursor; Step S3. Drilling holes in the second solid electrolyte membrane precursor obtained in Step S2 to obtain a plurality of first through holes, and filling the plurality of first through holes with a positive electrode lithium supplement to obtain a second solid electrolyte membrane; Step S4. Providing a positive electrode and a negative electrode, and sequentially stacking the positive electrode, the second solid electrolyte membrane, the first solid electrolyte membrane, and the negative electrode and pressing them to obtain the lithium-ion battery.

[0012] According to some embodiments of this application, the preparation method further includes step S3.5: perforating the second solid electrolyte membrane obtained in step S3 to obtain a plurality of second through holes, and filling the plurality of second through holes with solid electrolyte particles.

[0013] A third aspect of this application provides a lithium-ion battery module, the lithium-ion battery module comprising a plurality of electrically connected lithium-ion batteries as described above or lithium-ion batteries obtained by the preparation method described above.

[0014] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0015] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein: Figure 1 These are exemplary structural diagrams of lithium-ion batteries according to some embodiments of this application; Figure 2 This is an exemplary flowchart of a method for preparing a lithium-ion battery according to some embodiments of this application. Detailed Implementation

[0016] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The terms “comprising” or “including” and similar terms used herein mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “and / or” or “and / or” as used herein include any and all combinations of one or more of the associated listed items.

[0018] The following describes some preferred embodiments of this application. It should be noted that the following description is for illustrative purposes only and is not intended to limit the scope of protection of this application. The steps involved in this application may be performed precisely in sequence, or various steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0019] This application discloses a lithium-ion battery, which includes a positive electrode lithium replenisher. The positive electrode lithium replenisher is filled into a through-hole in another solid electrolyte membrane disposed between the positive electrode and the solid electrolyte membrane of the lithium-ion battery. The positive electrode lithium replenisher can effectively replenish the active lithium consumed during the first charge of the lithium-ion battery, thereby improving the total capacity, energy density, and cycle life of the lithium-ion battery.

[0020] refer to Figure 1 , Figure 1 These are exemplary configuration diagrams of lithium-ion batteries according to some embodiments of this application. Figure 1 As shown, the lithium-ion battery includes components along the thickness direction (corresponding to...). Figure 1 The positive electrode 100, the first solid electrolyte membrane 200, the negative electrode 300, and the second solid electrolyte membrane 400 located between the positive electrode 100 and the first solid electrolyte membrane 200 are stacked sequentially in the vertical direction.

[0021] The second solid electrolyte membrane 400 includes a positive electrode lithium replenisher. It is known that during the first charge of a lithium-ion battery, a solid electrolyte interphase (SEI) film forms on the surface of the negative electrode. This process irreversibly consumes active lithium ions from the positive electrode, preventing these active lithium ions from participating in subsequent charge-discharge cycles. Consequently, the actual usable capacity of the lithium-ion battery is lower than its theoretical capacity. The positive electrode lithium replenisher is used to replenish these active lithium ions. Within the target voltage range, it decomposes, releasing additional lithium ions to compensate for the lithium consumed in forming the SEI film, thereby improving the energy density and cycle life of the lithium-ion battery.

[0022] In some embodiments, the positive electrode lithium supplement may include, but is not limited to, lithium-rich lithium iron ferrite (LFO, Li5FeO4), lithium-rich lithium nickel ferrite (LNO, Li2NiO2), lithium-rich manganese-based lithium oxide (Li2O), lithium peroxide (Li2O2), lithium sulfide (Li2S), and lithium vanadium oxide (e.g., L...). i4+x V₂O₅, 0 < x < 1), lithium nitride derivatives (e.g., lithium nitride coated with lithium fluoride and organolithium compounds, Li ... 3x+y N x One or a mixture of FaClbBrcId, cobalt-based lithium supplements, etc. For example, the positive electrode lithium supplement is lithium-rich lithium iron phosphate (LFO) or lithium-rich lithium nickel phosphate (LNO).

[0023] In some embodiments, the positive electrode lithium supplement can be presented in powder form. An exemplary method may be to achieve this using a high-temperature solid-state method combined with mechanical grinding. For example, a lithium source (such as Li₂CO₃, LiOH) is mixed and ground with a metal oxide or salt (such as Fe₂O₃, NiO) in a specific stoichiometric ratio, and then sintered for a long time (several hours to tens of hours) at 600°C to 950°C in an inert atmosphere or vacuum to finally form the target lithium-rich compound (such as Li₅FeO₄). The obtained large particle product can be further subjected to mechanical ball milling, for example, feeding the large particle product into a ball mill for ball milling to obtain a small-particle-size positive electrode lithium supplement, such as micron-sized or nano-sized positive electrode lithium supplement particles, to utilize the rapid desorption of lithium ions.

[0024] In this application, the second solid electrolyte membrane 400 has a plurality of first through-holes 410, and the positive electrode lithium replenishment agent can fill the plurality of first through-holes 410. In some implementations, the first through-holes 410 can be formed using suitable physical and / or chemical methods. As an example, the plurality of first through-holes 410 can be formed by mechanically drilling to remove material from the surface and / or interior of the second solid electrolyte membrane 400. Alternatively, a high-energy laser beam (such as ultraviolet, infrared, femtosecond laser, etc.) can be focused on the surface of the second solid electrolyte membrane 400, and the local material can be melted, vaporized, or peeled off through photothermal effect (or photochemical effect) to form the plurality of first through-holes 410. Alternatively, a template-assisted method can be used to cover the surface of the second solid electrolyte membrane 400 with a pre-designed template (such as anodized aluminum oxide AAO, nanosphere array, porous silicon wafer, etc.), and the pore structure of the template can be copied onto the second solid electrolyte membrane 400 through physical filling or etching. As another example, chemical pore-opening methods include solvent etching (e.g., utilizing the solubility difference of a component of the second solid electrolyte membrane 400, selectively dissolving the component with a specific solvent to form pores), and plasma etching (e.g., utilizing active ions such as O in plasma). + Ar + Methods such as bombarding the surface of the second solid electrolyte membrane 400 with electrons to remove material and form pores through physical sputtering or chemical sputtering, chemical vapor etching (e.g., chemically reacting gaseous reactants such as H2S, Cl2, HF with the surface components of the second electrolyte layer 200 to generate volatile products and selectively remove material to form pores), and wet chemical etching (e.g., reacting specific chemical solutions such as acids, alkalis, complexing agents, etc. with the components of the second solid electrolyte membrane 400 to remove material through solution dissolution or coordination and thus form pores) can also be applied to this application and are not limited thereto.

[0025] In some embodiments, laser etching can be applied to create multiple first vias 410 in the second solid electrolyte membrane 400. A non-limiting illustration may be that after the second solid electrolyte membrane 400 is cleaned (e.g., rinsed with deionized water, anhydrous ethanol, dried with nitrogen, or vacuum dried) and completely dried, a suitable laser generator is selected (e.g., an ultraviolet laser is used when the second solid electrolyte membrane 400 is a polymer solid electrolyte layer; an infrared laser is used when the second solid electrolyte membrane 400 is an inorganic electrolyte ceramic such as LLZO). After optical system calibration and motion platform debugging, the shape, size, density, and depth of the first vias 410 are designed based on actual needs, and the laser is controlled using a planned path to begin emitting laser light and etching the second solid electrolyte membrane 400. After completion, the slag generated during the laser etching process is removed by physical cleaning, air blowing, or chemical cleaning, ultimately obtaining a second solid electrolyte membrane 400 with multiple first vias 410.

[0026] The filling of the positive electrode lithium replenishing agent in the first through hole 410 can be carried out using a physical filling method. For example, the physical filling can be achieved by driving the positive electrode lithium replenishing agent into the first through hole 410 through an external field (e.g., gravity, vacuum, pressure, etc.). Taking pressure as an example, the positive electrode lithium replenishing agent can be pressed into the first through hole 410 by a rolling process.

[0027] In this application, lithium ions are replenished by filling the first through hole 410 with a positive electrode lithium replenishing agent. After the lithium replenishment is completed, the inactive material formed by the positive electrode lithium replenishing agent will remain in the first through hole 410, thus avoiding waste of volumetric energy density.

[0028] In some embodiments, since the inactive material formed by the positive electrode lithium replenisher lacks electrochemical activity, it will affect the ion conduction of the lithium-ion battery to some extent. Therefore, multiple second through-holes 420 can be formed on the second solid electrolyte membrane 400 to fill solid electrolyte particles, thereby improving the ion conductivity of the lithium-ion battery.

[0029] The solid electrolyte particles include polymer solid electrolyte particles or inorganic solid electrolyte particles. Polymer solid electrolytes can be composed of a polymer and a lithium salt. Suitable, but not limiting, polymers that participate in the formation of polymer solid electrolytes may include, but are not limited to, polyether polymers, polycarbonate polymers, polyamide polymers, polyacrylate polymers, polysiloxane polymers, polyphosphazene polymers, polyolefin polymers, polyepoxide polymers, polyphosphate polymers, polyimide polymers, polyurethane polymers, and any combination thereof. For example, homopolymers such as polyethylene oxide (PEO) or copolymers (e.g., PEG-PPG block copolymers or PVDF-HFP) can participate in the formation of the polymer electrolyte. The lithium salt may include, but is not limited to, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium trifluoromethanesulfonate (LiOTF), lithium hexafluorophosphate (LiPF6), lithium hexafluoroborate (LiBF6), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium hexafluoroarsenate, lithium tri(pentafluoroethyl)-trifluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium cyclodifluoromethane-1,1-bis(sulfonyl)imide, lithium cyclodifluoromethane-1,1-bis(sulfonyl)imide, lithium bis(perfluoroethanesulfonyl)imide, lithium bis(fluoromalonic acid)borate, lithium tetracyanoborate, lithium dicyanotriazole, lithium dicyano-trifluoromethyl-imidazolium, lithium dicyano-pentafluoroethyl-imidazolium, and others.

[0030] Inorganic solid electrolytes used to form inorganic solid electrolyte particles may include halide solid electrolytes, sulfide solid electrolytes, oxide solid electrolyte materials, nitride solid electrolytes, hydride solid electrolytes, borate solid electrolytes, etc.

[0031] Suitable, but not limited, halide solid electrolytes may include, but are not limited to, LaF3, LiCl, LiI, etc., or those with the chemical formula Li a MX b This refers to lithium halide solid electrolytes, where M represents a metallic or metalloid element, including one or more of B, Si, Ge, As, Sb, Te, Al, Zn, Mg, Ca, Ba, Mn, Cd, Co, Yb, Y, Cr, In, Ga, Sr, Hf, Ti, Ta, Sn, Nb, Er, Sc, etc., and X represents a halogen element such as F, Cl, Br, I, etc. Examples include Li₂CdCl₄, Li₂MgCl₄, Li₂CdI₄, Li₂ZnI₄, Li₂ZrCl₆, Li₃YCl₆, and derivatives produced by doping or coating Li₃InCl₆ or related materials.

[0032] Suitable, but not limited, sulfide solid electrolytes may include, but are not limited to, Li2S-P2S5 and Li2S-P2S5–MS. x (M=Si, Ge, Sn, 0≤x≤2), Li 9.6 P3S 12 Li7P3S 11 Li7P2S8I, Li 10 SnP2S 12 Li 10 SiP2S 12 Li9P3S9O3, LGPS(Li 10 GeP2S 12 Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li6PS5X (X=Cl, Br, I), Li3PS4-X (X=Cl, Br, I), Li4SnS4-X (X=Cl, Br), Li 3.25 Ge 0.25 P 0.75 S4, Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.54 Si 1.74 P 1.44 S11.7 Cl 0.3 Li 10.35 Ge 1.35 P 1.65 S 12 Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li 10 (Ge 0.5 Sn 0.5 P2S 12 Li 10 (Si 0.5 Sn 0.5 P2S 12 Li6 (PS5) 0.7 (GeS4) 0.3 Cl、Li 7.5 P 2.5 Sn 0.5 S 10.5 Cl 1.5 Li6PS5Cl 0.5 Br 0.5 Li6PS5I 0.2 Cl 0.8 Li5SnS2C l3 Li 10 P3S 12 Cl2, Li7P2S 8.5 Cl 0.5 Derivatives produced by doping or coating with materials such as or any combination thereof or related materials.

[0033] Suitable, but not limited, oxide solid electrolytes may include, but are not limited to, NASICON-type solid electrolytes such as LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3, and Li 1+x Al x Ge 2-x (PO4)3(LAGP, where 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x (PO4)3(LATP, where 0 ≤ x ≤ 2), Li 1+x Y x Zr 2-x(PO4)3(LYZP, where 0 ≤ x ≤ 2), Li 1.3 Al 0.3 Ti 1.7 (PO4)3, etc., perovskite-type solid electrolytes such as Li 3x La( 2 / 3-x )TiO3 (LLTO, where 0 < x < 0.25), LiSr 1.65 Zr 1.3 Ta 1.7 O9, Li 2x-y Sr 1-x Ta y Zr 1-y O3 (where x = 0.75y and 0.60 < y < 0.75), etc., LISICON-type solid electrolytes such as Li 14 ZnGe4O 16 、Li4SiO4、LiGeO4, etc., garnet-type solid electrolytes such as Li7La3Zr2O 12 、Li 6.5 La3Zr 1.75 Te 0.25 O 12 、Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 、Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Al 0.25 La3Zr2O 12 、Li 6.75 La3Zr 1.75 Nb 0.25 O 12 、Li 6.75 La3Zr 1.75 Nb 0.25 O 12 etc., or derivatives produced by doping or coating improvement with any combination or related materials thereof.

[0034] Some suitable but non-limiting nitride solid electrolytes can include, but are not limited to, Li3N, Li7PN4, LiSi2N3, Li9N2Cl3, etc. Some suitable but non-limiting hydride solid electrolytes can include, but are not limited to, LiBH4, LiBH4-Li X(X = Cl, Br, or I), LiNH2, Li2NH, LiBH4-LiNH2, Li3AlH6, etc. Some suitable but not limited borate solid electrolytes may include, but are not limited to, Li2B4O7, Li2O-B2O3-P2O5, Li2B... 10 H 10 -Li2B 12 H 12 Examples include Li7N2I-0.5LiOH. Derivatives of these electrolytes obtained through substitution, doping, modification, and compositing can also serve as the inorganic solid electrolytes described in this application. For instance, bromine-substituted or partially substituted Li2ZrCl6, such as Li2ZrCl... 6-x Br x Rare earth metals such as lanthanum or yttrium-doped Li6PS5Br, and LLZO deposited on indium (In) surfaces, etc. It should be noted that the above examples are for illustrative purposes only and are not intended to limit the scope of this application.

[0035] When particles are formed, they can be prepared using methods such as mechanical ball milling (e.g., weighing reactants according to stoichiometric ratio and then ball milling in an inert atmosphere (e.g., Ar / He), followed by annealing), high-temperature melt quenching (e.g., heating a mixture of reactants to a melt in an inert atmosphere, then rapidly cooling the melt and annealing), solution processing (e.g., dissolving the reaction precursor in an organic solvent, then slowly evaporating the solvent in an inert atmosphere, followed by sintering to remove residual solvent and crystallizing), chemical vapor deposition (e.g., depositing a thin film on a heated substrate using vaporized feedstock and then annealing at a low temperature), and solid-state reaction (e.g., uniformly mixing powdered reactants, pressing them into sheets, heating and holding them in an inert atmosphere, followed by rapid cooling). This application does not impose specific limitations.

[0036] For filling solid electrolyte particles, a solution permeation drying method can be used. For example, solid electrolyte particles are dispersed in a solvent (with a dispersant added if necessary to prevent agglomeration) to form a suspension, and a second solid electrolyte membrane 400 is immersed in this suspension to allow the solid electrolyte particles to enter the pores. Subsequently, drying or solvent displacement fixes the particles within the pores. Alternatively, a mechanical pressing method can be used. For example, solid electrolyte particles are pressed into the pores of the second solid electrolyte membrane 400 using external pressure, achieving physical bonding between the particles and the electrolyte layer matrix through mechanical force. Alternatively, an electrochemical deposition method can be used. For example, an electric field is used to drive the deposition of solid electrolyte particles (typically conductive or ionic conductor particles) within the pores. Alternatively, a vapor deposition method can be used. For example, solid electrolyte particles are grown within the pores through vapor-phase reaction or physical vapor deposition (such as sputtering or evaporation). Any suitable and applicable method can be used in this application.

[0037] In some embodiments, the method for forming the second via 420 on the second solid electrolyte membrane 400 can be the same as that for the first via 410. For example, it can also be formed using laser etching. The diameters of the formed first via 410 and second via 420 can be 1 μm-20 μm. For example, the diameters of the first via 410 and second via 420 are 3 μm-17 μm. Alternatively, the diameters of the first via 410 and second via 420 are 5 μm-15 μm. Alternatively, the diameters of the first via 410 and second via 420 are 8 μm-13 μm. Alternatively, the diameters of the first via 410 and second via 420 can be any value within the above-mentioned range. In some implementations, the diameters of the first via 410 and second via 420 are the same. In some implementations, the diameters of the first via 410 and second via 420 can be different. For example, the diameter of the first through hole 410 is 10 μm, and the diameter of the second through hole 420 is 15 μm.

[0038] In some embodiments, the diameter of the second through-hole 420 is larger than the diameter of the first through-hole 410, allowing it to hold more solid electrolyte particles, thereby compensating for the decrease in ionic conductivity of the second solid electrolyte membrane 400 caused by the introduction of the positive electrode lithium replenishment agent through the opening. Both the first through-hole 410 and the second through-hole 420 can be circular. Compared to other shapes, circular holes distribute stress more evenly in all directions, making them less prone to tearing or cracking in any particular direction. It should be noted that the shape of the holes (including the first through-hole 410 and the second through-hole 420) can also be other regular shapes similar to circles, such as regular polygons with rounded corners. Holes of this shape also distribute stress evenly in all directions, similarly making them less prone to tearing / cracking.

[0039] In some embodiments, the first through-hole 410 and the second through-hole 420 are arranged in an ordered or random manner on the second solid electrolyte membrane 400. For example, the first through-hole 410 and the second through-hole 420 are arranged in alternating queues on the second solid electrolyte membrane 400. Each queue contains the same type of through-hole, and the distance between adjacent holes is the same. Alternatively, the first through-hole 410 and the second through-hole 420 are randomly distributed on the second solid electrolyte membrane 400. The distance between adjacent holes can be the same or different.

[0040] To maximize the replenishment of active lithium without compromising the mechanical strength and stability of the second solid electrolyte membrane 400, the total volume of the plurality of first through-holes 410 can be set to account for 60%-80% of the total volume of the second solid electrolyte membrane 400. For example, the total volume of the plurality of first through-holes 410 may account for 60%, 64%, 68%, 72%, 76%, 80%, or any value within the above range. Optionally or preferably, the total volume of the plurality of first through-holes 410 accounts for 75% of the total volume of the second solid electrolyte membrane 400.

[0041] To improve the ionic conductivity of the second solid electrolyte membrane 400, the total volume of the plurality of second vias can be set to account for 1%-40% of the total volume of the second solid electrolyte membrane 400. For example, the total volume of the plurality of second vias may account for 1%, 5%, 10%, 15%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40% of the total volume of the second solid electrolyte membrane 400, or any value within the above range. Optionally or preferably, the total volume of the plurality of second vias 420 accounts for 5% of the total volume of the second solid electrolyte membrane 400.

[0042] In some embodiments, the central axes of the first through hole 410 and the second through hole 420 are wholly or partially offset from the thickness direction. For ease of explanation, ... Figure 1 The thickness direction is perpendicular to the center. Figure 1 The diagram also shows that the central axes of some of the first through-holes 410 and the second through-hole 420 deviate from the vertical direction, or are inclined to the vertical direction, while the central axes of the first through-hole 410 and the second through-hole 420 are parallel to the vertical direction. The deviation angle between the central axis of the first through-hole 410 and the vertical direction and the vertical direction can be between 5° and 85°. For example, the deviation angle can be 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, etc., or any value within the above deviation angle range. Optionally or preferably, the deviation angle is 15°. In some embodiments, the deviation angles of the central axes of the first through-hole 410 and the second through-hole 420 from the thickness direction of the solid electrolyte membrane are different. For example, the deviation angle of the first through-hole 410 is 25°, and the deviation angle of the second through-hole 420 is 5°. The off-vertical pores can hold more positive electrode lithium replenishment / solid electrolyte particles, thereby replenishing more active lithium ions to improve the cycle performance and lifespan of lithium-ion batteries, and provide better ionic conductivity. Of course, Figure 1This is merely an example; the first through hole 410 and the second through hole 420 could also both be offset holes, which does not limit this application.

[0043] The second solid electrolyte membrane 400 used to open the first through-hole 410 and the second through-hole 420 can be prepared using one or more solid electrolytes with ionic conductivity. The solid electrolyte may include polymer solid electrolytes, inorganic solid electrolytes such as halide solid electrolytes, sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, hydride solid electrolytes, borate solid electrolytes, etc. Exemplary descriptions of the above solid electrolytes can be found in the foregoing content and will not be repeated here.

[0044] It is understood that the solid electrolyte in this application is not required to be selected from any single one of the above-mentioned solid electrolytes, but may be selected from one or more of the above-mentioned solid electrolytes, such as a mixture of a sulfide solid electrolyte and a halide solid electrolyte, or a mixture of an oxide solid electrolyte and two halide solid electrolytes. Without departing from the inventive concept of this application, the use of known conventional solid electrolytes should be considered within the scope of protection of this application.

[0045] In some embodiments, the second solid electrolyte membrane 400 comprises a polymer solid electrolyte. An example of a polymer solid electrolyte membrane is that the second solid electrolyte membrane 400 is made of a polyepoxy vinyl polymer electrolyte (PEO) and a lithium salt, LiTFSI. Considering the overall conductivity, physical strength, and energy density of the solid electrolyte membrane, the thickness of the second solid electrolyte membrane 400 can be 10-20 μm. For example, the thickness of the second solid electrolyte membrane 400 is 10 μm, 13 μm, 15 μm, 17 μm, 20 μm, etc., or other values ​​within the aforementioned range. Optionally or preferably, the thickness of the second solid electrolyte membrane 400 is 15 μm.

[0046] An exemplary method for obtaining a second solid electrolyte membrane 400 (i.e., a polymer solid electrolyte membrane) includes wet coating. The polymer and lithium salt are weighed at a predetermined mass ratio, dissolved in a solvent, stirred until homogeneous, and then coated onto a release film. After drying, the second solid electrolyte membrane 400 is obtained.

[0047] The lithium-ion battery disclosed in this application includes a positive electrode 100 and a negative electrode 300, which may include a current collector and an active material layer located on the current collector and at least one side of the current collector.

[0048] The active material layer of the positive electrode 100 includes a positive electrode active material, which can be a material containing metal ions capable of intercalating or deintercalating lithium ions, including lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal fluorides, transition metal sulfides, or transition metal nitrides. Examples include LiCoO2, LiNiO2, LiMnO3, LiMn2O3, LiMnO2, Li(NiCoAl)O2, Li2CuO2, and LiNi... x Mn 2-x O4, LiNi 1-x M x O2 (M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, x=0.01-0.3), LiMn 1- x M x O2 (M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01-0.1), Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn), etc., but not limited to these.

[0049] In some embodiments, the active material layer of the positive electrode 100 further includes a solid electrolyte, for example, the same as or similar to the aforementioned inorganic solid electrolyte. In some implementations, the solid electrolyte included in the active material layer of the positive electrode 100 may be a mixture of one or more sulfide solid electrolytes and one or more halide solid electrolytes. For example, the solid electrolyte may be a composite of the sulfide solid electrolyte Li6PS5Cl and the halide solid electrolyte Li2ZrCl6.

[0050] The active material layer of the negative electrode 300 includes a negative electrode active material, or it may be a material containing metal ions capable of intercalating or deintercalating lithium ions. Examples of such materials include metals (such as Li, Ag, Al, Bi, Cu, Ga, Ge, In, Ni, Pb, Sb, Si, Sn, Sr, Zn, etc., or alloys or compounds of the above metals, such as Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, TiO2-Li4Ti5O). 12 The active material layer of the negative electrode can be a Li-C composite layer obtained by laminating a lithium metal layer and a carbon layer. This can be a Li-C composite layer. The active material layer of the negative electrode can be Li-Al alloys, Ag-C alloys, etc., carbon materials (such as graphite including natural / artificial graphite, carbon fibers, soft carbon, hard carbon, crystalline carbon, amorphous carbon, etc.), silicon compounds (such as silicon, silicon-carbon composites), or composite materials formed by metals and carbon / silicon. In some embodiments, the active material layer of the negative electrode can be a Li-C composite layer obtained by laminating a lithium metal layer and a carbon layer.

[0051] The current collector can be implemented using a metal plate with electronic conductivity. All currently known current collectors can be used in this application. For example, the positive current collector used in the positive electrode 100 can be aluminum foil, and the negative current collector used in the negative electrode 300 can be copper foil.

[0052] In some embodiments, the positive electrode 100 and / or the negative electrode 300 may further contain at least one of a binder and a conductive agent. Some exemplary binders may include, but are not limited to, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, polyethylene, polypropylene, carboxymethyl cellulose, cellulose, etc. Exemplary conductive agents may include, but are not limited to, carbon-based materials such as graphite (natural or artificial graphite, etc.), carbon black (acetylene black or Ketjen black, etc.), carbon nanotubes, graphene, etc.; metal-based materials such as metal powders (aluminum powder, nickel powder, etc.), metal oxides (titanium oxide, etc.), metal whiskers (alumina, oxidizing agents, etc.); conductive polymers such as polyaniline, polypyrrole, polythiophene, etc.; and conductive fibers such as carbon fibers, metal fibers, metal compound fibers, polymer fibers, etc.

[0053] The lithium-ion battery disclosed in this application includes a first solid electrolyte membrane 200, which may include an inorganic electrolyte selected from one or more of the following, and a mixture thereof with one or more of a halide solid electrolyte. Exemplarily, the first solid electrolyte membrane 200 is made using a sulfide solid electrolyte LiPSCl. In some embodiments, the first solid electrolyte membrane 200 is selected from a mixture of sulfide solid electrolytes and halide solid electrolytes, a combination that has superior overall performance.

[0054] The first solid electrolyte membrane 200 may further include an adhesive, which may include a fiberizable adhesive. Exemplarily, the adhesive may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), cellulose, nanocellulose, nanofibers (CNF), polyaniline (PANI), polypyrrole (PPy), polyrotaxane, etc., or any combination thereof.

[0055] The lithium-ion battery disclosed in this application has an additional solid electrolyte membrane containing a positive electrode lithium replenisher disposed between the positive electrode and the solid electrolyte membrane. The positive electrode lithium replenisher can be used to replenish the active lithium consumed during the first charge of the lithium-ion battery. Since the positive electrode lithium replenisher fills the pores in this additional solid electrolyte membrane, the inactive material formed after lithium replenishment remains in the pores of the second solid electrolyte membrane, preventing waste of volumetric energy density. Simultaneously, the aforementioned additional solid electrolyte layer also contains solid electrolyte particles filled with pores, which can improve ionic conductivity.

[0056] This application discloses, in another aspect, a method for preparing the above-mentioned lithium-ion battery. As an exemplary but not limiting illustration, the preparation method may include the following steps: S1. The first solid electrolyte membrane is obtained by mixing an inorganic solid electrolyte with a binder and forming a film. S2. A polymer solution prepared using a polymer solid electrolyte is coated and dried to obtain a second solid electrolyte membrane precursor; S3. Drill holes in the second solid electrolyte membrane precursor obtained in step S2 to obtain multiple first through holes, and fill the multiple first through holes with positive electrode lithium replenishing agent to obtain the second solid electrolyte membrane; S4. Provide a positive electrode and a negative electrode, and stack the positive electrode, the second solid electrolyte membrane, the first solid electrolyte membrane and the negative electrode in sequence and press them together to obtain the lithium-ion battery.

[0057] In some feasible implementations, the inorganic solid electrolyte and binder can be weighed according to a preset mass ratio and then added to a mixing device for mixing. The binder can be a fiberizable binder, such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or polyacrylic acid (PAA). The mixing device can be any suitable mixer, such as a high-speed mixer or an air-flow mixer. Taking a high-speed mixer as an example, the rotation speed used for mixing to fiberize the binder can be between 1000 rpm and 10000 rpm, for example, 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm, 5000 ppm, 6000 ppm, 7000 ppm, 8000 ppm, 9000 ppm, or 10000 ppm. In some implementations, this rotation speed is 5000 rpm. After mixing, the resulting mixture can be pressed into a film using molding, calendering, or rolling to obtain the first solid electrolyte membrane. Taking roll forming as an example, the above mixture can first be pre-formed, such as kneaded into blocks or ground into dough, and then placed into a roll press for hot roll forming. This hot roll forming can include multiple roll forming processes. For example, multiple roll forming processes can be performed by gradually reducing the roll gap, ultimately resulting in a first solid electrolyte membrane with the target thickness. The temperature during the roll forming process can be controlled between 30-50°C. For example, 30°C, 35°C, 40°C, 45°C, 50°C, etc.

[0058] For step S2, after weighing the polymer (e.g., polyethylene oxide, PEO) and lithium salt (e.g., LiTFSI) in a mass-to-molar ratio, the solution is dissolved in a solvent (e.g., acetonitrile, N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, dimethoxyethane, nitromethane, acetone, pyridine, ethanol, dimethylacetamide, or water, or a combination of two or more). The resulting solution is added to a high-speed mixer and mixed uniformly to obtain an electrolyte slurry. Alternatively, ultrasonic dispersion can be used to further refine the particles to achieve uniform particle size. This electrolyte slurry can be coated onto a release film (e.g., polyethylene terephthalate (PET) release film, polypropylene (PP) release film, polyethylene (PE) release film, polyimide (PI) release film, polyvinyl chloride (PVC) release film, etc.). The release film can be cleaned (e.g., ultrasonically cleaned with acetone / ethanol) and dried (e.g., vacuum dried at 80-120°C). After coating, drying can be performed, for example, by gradually increasing the temperature. After drying, it can continue drying in a vacuum environment with hot air circulation for a set time, such as 12 hours, to more thoroughly remove the solvent. After completion, the membrane is demolded to obtain the second solid electrolyte membrane precursor. Depending on the actual requirements, the thickness of the second solid electrolyte membrane precursor can be 10-20 μm. For example, the thickness of the second solid electrolyte membrane precursor is 15 μm.

[0059] In step S3, forming multiple first through-holes on the second solid electrolyte membrane precursor can be achieved using laser drilling. One exemplary approach is to keep the laser generator stationary while moving the second solid electrolyte membrane precursor. For example, the second solid electrolyte membrane precursor can be placed on a moving platform, such as a conveyor belt. By controlling the movement of the conveyor belt, the movement of the second solid electrolyte membrane precursor can be controlled, allowing the laser beam emitted by the laser generator to drill holes at different positions on the second solid electrolyte membrane precursor. Another example is to fix the position of the second solid electrolyte membrane precursor while moving the laser generator. For example, the second solid electrolyte membrane precursor can be fixed on a sample stage, and the laser generator, in conjunction with a biaxial galvanometer or a movable platform, can adjust and change the position of the emitted laser beam, thereby drilling holes at different positions on the second solid electrolyte membrane precursor. By controlling parameters such as the position adjustment speed of the second solid electrolyte membrane precursor / laser generator, pulse output energy, pulse repetition frequency, and / or pulse width during the laser drilling process, the number / density of holes and the diameter of the holes can be controlled. Upon completion, multiple second through-holes will be formed on the second solid electrolyte membrane precursor. For example, by using a laser generator in conjunction with a biaxial galvanometer, the laser beam is focused onto the surface of the second solid electrolyte membrane precursor. The pulsed laser power is controlled to be 3.0W and the number of pulses is 20. The biaxial galvanometer controls the laser to advance in single steps of 200μm, thus creating a vertical channel with a diameter of 10μm as the first through hole.

[0060] The plurality of first through-holes can be filled with a positive electrode lithium supplement (e.g., lithium iron phosphate, lithium nickel oxide, etc.). An exemplary method is to use mechanical pressure to press metal particles into the first through-holes. For example, the positive electrode lithium supplement can be pressed in by rolling. Before rolling, the perforated second solid electrolyte membrane precursor can be pretreated, including cleaning (e.g., ultrasonic cleaning with deionized water and detergent, or vacuum drying after cleaning with ethanol / acetone), surface activation (e.g., using plasma treatment to increase surface energy to enhance adhesion to metal particles), and drying (e.g., vacuum drying). Subsequently, the positive electrode lithium supplement is pre-loaded into the first through-holes, and the second solid electrolyte membrane precursor carrying the positive electrode lithium supplement is fed into a rolling mill for rolling. Pre-pressing can be performed first, using low pressure (e.g., 0.5 MPa-1 MPa) to initially attach the positive electrode lithium supplement into the first through-holes. Then, the pressure is increased (e.g., 10 MPa-50 MPa) for formal rolling. This rolling process can be multi-pass rolling, which can improve the uniformity of the positive electrode lithium replenishment filling. During rolling, the flexibility of the second solid electrolyte membrane precursor can be improved by adjusting the rolling temperature, thereby reducing the resistance to the positive electrode lithium replenishment being pressed into the first through-hole. For example, the rolling temperature can be between 30°C and 50°C. In addition, the positive electrode lithium replenishment can be replenished at any time during the intervals of multi-pass rolling to increase the amount of positive electrode lithium replenishment being pressed into the first through-hole.

[0061] In step S4, the positive electrode is provided by pressing a mixture of a homogeneously mixed positive electrode active material, a solid electrolyte, a conductive agent, and a binder. This mixing can be carried out in a high-speed mixer, similar to or the same as the mixing of the inorganic solid electrolyte and binder in step S1. The rotation speed during this mixing process can be 1000 rpm to 10000 rpm, for example, 5000 rpm. The pressing can be performed using roller pressing. Of course, other pressing methods such as calendering and molding can also be applied here.

[0062] The provision of the negative electrode includes the use of corresponding negative electrode active materials. For example, for graphite-based negative electrodes, artificial graphite can be obtained through pretreatment, crushing / grading, mixing, granulation, graphitization, grinding, sieving, and demagnetization. Natural graphite can be obtained through crushing / grading, grinding, purification, modification, and demagnetization. As another example, for silicon-based negative electrodes (such as carbon-coated silicon suboxide SiO / C), after raw material preparation based on silicon powder and silicon dioxide, it is obtained through nano-processing, carbon coating, grinding, sieving, and demagnetization. For ease of use, the above-mentioned negative electrode active materials can be shaped, for example, pressed into a regular shape. In some embodiments, the active material layer of the negative electrode can be a Li-C composite layer obtained by stacking and pressing a lithium metal layer and a carbon layer.

[0063] Of course, the provision of the above-mentioned positive and negative electrodes also includes combining the active layer with the corresponding current collector to finally obtain the positive electrode sheet and the negative electrode sheet used.

[0064] In some embodiments, the pressing of the positive electrode, the second solid electrolyte membrane, the first solid electrolyte, and the negative electrode after sequential stacking may include layer-by-layer pressing followed by overall pressing (for example, first pressing the positive electrode and the second solid electrolyte membrane, then attaching the first solid electrolyte membrane and pressing, and finally attaching the negative electrode for overall pressing), or using isostatic pressing or pulse hot pressing. In some embodiments, the pressing may be performed using isostatic pressing. Isostatic pressing can result in a final product (i.e., the lithium-ion battery) with uniform density (porosity <1%) and good interfacial contact, making it suitable for the composite pressing of solid electrolyte membranes and positive and negative electrodes.

[0065] The method for preparing a lithium-ion battery disclosed in this application may further include step S3.5: perforating the second solid electrolyte membrane obtained in step S3 to obtain a plurality of second through holes, and filling the plurality of second through holes with solid electrolyte particles.

[0066] For drilling multiple second through-holes into the second solid electrolyte layer precursor filled with positive electrode lithium replenishment, the method can be the same as or similar to the drilling method in step S3. For example, laser drilling can also be used: using a laser generator and a biaxial galvanometer, the laser beam is focused on the surface of the second solid electrolyte membrane precursor, the pulsed laser power is controlled at 3.0W, the number of pulses is 20, and the biaxial galvanometer controls the laser to advance 200μm in a single step, thus creating a vertical channel with a diameter of 15μm as the second through-hole. For filling solid electrolyte particles, mechanical pressure, such as rolling, can also be used to press them into the second through-holes. See step S3 for details. Step S3.5 can follow step S3, and after completion, step S4 will be executed to obtain the final battery.

[0067] This application also discloses a lithium-ion battery module comprising multiple lithium-ion batteries arranged in a folded, stacked, or combined manner as described above. This lithium-ion battery module can be applied to electrically driven vehicles, including but not limited to electric vehicles, hybrid vehicles, and energy storage devices such as energy storage systems.

[0068] The present application will be further described in detail below with reference to embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection claimed in this application.

[0069] Example 1 - Preparation of Lithium-ion Batteries 1. Preparation of the second solid electrolyte membrane 1.1 Polyethylene oxide (PEO, molecular weight = 4,000,000 g / mol) and lithium salt LiTFSI were dissolved in acetonitrile to prepare a 4 wt% polymer solution. The [EO] / [Li] ratio was... + The molar ratio of [ ] is 15:1. After stirring and mixing evenly, it is coated onto a release film. It is dried overnight, and then vacuum dried at 100°C for 12 hours. The thickness of each electrolyte film layer is approximately 15 μm.

[0070] 1.2 The PEO film (15 μm thick) prepared in the above steps was placed on the sample stage. The laser beam was focused on the surface of the PEO film by using a laser and a biaxial galvanometer. The pulsed laser power was controlled to be 3.0 W and the number of pulses was 20. The biaxial galvanometer controlled the laser to advance 200 μm in a single step to prepare a vertical channel with a diameter of 10 μm. The total volume of the filling hole accounted for 75% of the volume of the PEO film.

[0071] 1.3 The positive electrode lithium replenishing agent lithium iron ferrite powder (7μm in diameter) was pressed into the filling hole by a rolling process at a pressure of 50MPa and a temperature of 20℃ to obtain the second solid electrolyte membrane.

[0072] 2. Preparation of solid electrolyte membranes Solid electrolyte particles were fiberized with 1 wt% PTFE (at 5000 rpm) and then rolled to prepare a composite positive electrode membrane. The temperature was controlled at 30-50℃ during the rolling process. This yielded the first solid electrolyte membrane. The solid electrolyte in the first solid electrolyte membrane was LiPSCl.

[0073] The first and second solid electrolyte membranes are combined using a rolling mill to prepare a two-layer composite solid electrolyte membrane.

[0074] 3. Manufacturing of positive electrode, negative electrode and battery The positive electrode active material, solid electrolyte (a composite of sulfide Li6PS5Cl and halide Li2ZrCl6 in a mass ratio of 1:1), conductive agent, and binder were mixed in a high-speed mixer at a ratio of 7:2.9:0.2:0.1 (speed of 5000 r / min), and a composite positive electrode film was prepared by rolling. The temperature was controlled at 30-50℃ during the rolling process.

[0075] The prepared positive electrode film is matched with a lithium-based negative electrode (a Li-C composite negative electrode is obtained by rolling a carbon layer with a lithium metal sheet), and the composite solid electrolyte film is stacked with the composite positive electrode (in which the second solid electrolyte film in the composite solid electrolyte film is in contact with the composite positive electrode). Then, it is isostatically densified and assembled into a 2cm×2cm all-solid-state soft-pack battery.

[0076] Example 2 - Preparation of Lithium-ion Batteries 1. Preparation of the second solid electrolyte membrane 1.1 Polyethylene oxide (PEO, molecular weight = 4,000,000 g / mol) and lithium salt LiTFSI were dissolved in acetonitrile to prepare a 4 wt% polymer solution. The [EO] / [Li] ratio was... + The molar ratio of [ ] is 15:1. After stirring and mixing evenly, it is coated onto a release film. It is dried overnight, and then vacuum dried at 100°C for 12 hours. The thickness of each electrolyte film layer is approximately 15 μm.

[0077] 1.2 The PEO film (15 μm thick) prepared in the above steps was placed on the sample stage. The laser beam was focused on the surface of the PEO film by using a laser and a biaxial galvanometer. The pulsed laser power was controlled to be 3.0 W and the number of pulses was 20. The biaxial galvanometer controlled the laser to advance 200 μm in a single step to prepare a vertical channel with a diameter of 10 μm. The total volume of the filling hole accounted for 75% of the volume of the PEO film.

[0078] 1.3 The positive electrode lithium supplement powder (7μm in diameter) was pressed into the filling hole by a rolling process at a pressure of 50MPa and a temperature of 20℃ to obtain the second solid electrolyte membrane.

[0079] 2. Preparation of solid electrolyte membranes Solid electrolyte particles were fiberized with 1 wt% PTFE (at 5000 rpm) and then rolled to prepare a composite positive electrode membrane. The temperature was controlled at 30-50℃ during the rolling process. This yielded the first solid electrolyte membrane. The solid electrolyte in the first solid electrolyte membrane was LiPSCl.

[0080] The first and second solid electrolyte membranes are combined using a rolling mill to prepare a two-layer composite solid electrolyte membrane.

[0081] 3. Manufacturing of positive electrode, negative electrode and battery The positive electrode active material, solid electrolyte (a composite of sulfide Li6PS5Cl and halide Li2ZrCl6 in a mass ratio of 1:1), conductive agent, and binder were mixed in a high-speed mixer at a ratio of 7:2.9:0.2:0.1 (speed of 5000 r / min), and a composite positive electrode film was prepared by rolling. The temperature was controlled at 30-50℃ during the rolling process.

[0082] The prepared positive electrode film is matched with a lithium-based negative electrode (a Li-C composite negative electrode is obtained by rolling a carbon layer with a lithium metal sheet), and the composite solid electrolyte film is stacked with the composite positive electrode (in which the second solid electrolyte film in the composite solid electrolyte film is in contact with the composite positive electrode). Then, it is isostatically densified and assembled into a 2cm×2cm all-solid-state soft-pack battery.

[0083] Example 3 - Preparation of Lithium-ion Batteries 1. Preparation of the second solid electrolyte membrane 1.1 Polyethylene oxide (PEO, molecular weight = 4,000,000 g / mol) and lithium salt LiTFSI were dissolved in acetonitrile to prepare a 4 wt% polymer solution. The [EO] / [Li] ratio was... + The molar ratio of [ ] is 15:1. After stirring and mixing evenly, it is coated onto a release film. It is dried overnight, and then vacuum dried at 100°C for 12 hours. The thickness of each electrolyte film layer is approximately 15 μm.

[0084] 1.2 The PEO film (15 μm thick) prepared in the above steps was placed on the sample stage. The laser beam was focused on the surface of the PEO film by using a laser and a biaxial galvanometer. The pulsed laser power was controlled to be 3.0 W and the number of pulses was 20. The biaxial galvanometer controlled the laser to advance 200 μm in a single step to prepare a vertical channel with a diameter of 10 μm. The total volume of the filling hole accounted for 75% of the volume of the PEO film.

[0085] 1.3 The positive electrode lithium replenishing agent lithium iron ferrite powder (7μm in diameter) is pressed into the filling hole by a rolling process at a pressure of 50MPa and a temperature of 20℃.

[0086] 1.4 The thin film prepared in step 1.3 was placed on the sample stage and a second drilling was performed. The laser beam was focused on the surface of the PEO thin film by using a laser and a biaxial galvanometer. The pulse laser power was controlled to be 3.0W and the number of pulses was 20. The biaxial galvanometer controlled the laser to advance 200μm in a single step to prepare a vertical channel with a diameter of 15μm. The total volume of the filling hole accounted for 3% of the volume of the PEO thin film.

[0087] 1.5 The oxide solid electrolyte LLTO (600 nm in diameter) is pressed into the second cavity by a rolling process to obtain the second solid electrolyte membrane.

[0088] 2. Preparation of solid electrolyte membranes Solid electrolyte particles were fiberized with 1 wt% PTFE (at 5000 rpm) and then rolled to prepare a composite positive electrode membrane. The temperature was controlled at 30-50℃ during the rolling process. This yielded the first solid electrolyte membrane. The solid electrolyte in the first solid electrolyte membrane was LiPSCl.

[0089] The first and second solid electrolyte membranes are combined using a rolling mill to prepare a two-layer composite solid electrolyte membrane.

[0090] 3. Manufacturing of positive electrode, negative electrode and battery The positive electrode active material, solid electrolyte (a composite of sulfide Li6PS5Cl and halide Li2ZrCl6 in a mass ratio of 1:1), conductive agent, and binder were mixed in a high-speed mixer at a ratio of 7:2.9:0.2:0.1 (speed of 5000 r / min), and a composite positive electrode film was prepared by rolling. The temperature was controlled at 30-50℃ during the rolling process.

[0091] The prepared positive electrode film is matched with a lithium-based negative electrode (a Li-C composite negative electrode is obtained by rolling a carbon layer with a lithium metal sheet), and the composite solid electrolyte film is stacked with the composite positive electrode (in which the second solid electrolyte film in the composite solid electrolyte film is in contact with the composite positive electrode). Then, it is isostatically densified and assembled into a 2cm×2cm all-solid-state soft-pack battery.

[0092] Comparative Example 1: The difference between Comparative Example 1 and the above embodiment is that the positive electrode lithium replenishing agent is directly added to the positive electrode slurry, rather than filling the through-holes formed on the second solid electrolyte membrane.

[0093] Test Example: Cyclic Performance Test The pouch battery was subjected to charge-discharge tests. The test voltage window was 2.5-4.25V, the test pressure was 2MPa, and the temperature was 60℃. After two cycles at a 0.33C rate, a cycle test was then performed at a 1C current. The discharge capacity of the first and 50th cycles at 1C was recorded. The cycle retention rate was calculated as: 1C - 50th cycle capacity / 1C - 1st cycle capacity. The test results are shown in Table 1.

[0094] Table 1 Cyclic performance test results As shown in Table 1, this application can significantly improve the cycle characteristics of lithium-ion batteries and extend battery life by adding positive electrode lithium replenishing agent and solid electrolyte particles to the solid electrolyte membrane.

[0095] This application has described the basic concepts. Obviously, for those skilled in the art, the above detailed disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0096] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this application do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0097] Similarly, it should be noted that, in order to simplify the description of this application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of this application sometimes combines multiple features into one embodiment or its description. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned in the claims. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0098] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other modifications may also fall within the scope of this application. Therefore, alternative configurations of the embodiments of this application are considered as examples and not limitations, and are regarded as consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly described and illustrated in this application.

Claims

1. A lithium-ion battery, comprising a positive electrode, a first solid electrolyte membrane, and a negative electrode sequentially stacked along the thickness direction; characterized in that, The lithium-ion battery further includes a second solid electrolyte membrane, which is located between the positive electrode and the first solid electrolyte membrane; wherein... The second solid electrolyte membrane has multiple first through-holes, and the first through-holes are filled with positive electrode lithium replenishment agent.

2. The lithium-ion battery according to claim 1, characterized in that, The positive electrode lithium replenishing agent includes one or a mixture of more than one of lithium iron ferrite, lithium nickel ferrite, lithium manganese-based lithium oxide, lithium peroxide, lithium sulfide, lithium vanadium oxide, lithium nitride derivatives, and cobalt-based lithium replenishing agents.

3. The lithium-ion battery according to claim 1, characterized in that, The second solid electrolyte membrane comprises a polymer solid electrolyte with a thickness of 10 μm-20 μm.

4. The lithium-ion battery according to any one of claims 1-3, characterized in that, The second solid electrolyte membrane also has a plurality of second through-holes, which are filled with solid electrolyte particles.

5. The lithium-ion battery according to claim 4, characterized in that, The central axes of the first through hole and the second through hole are all or partly deviated from the thickness direction of the second solid electrolyte membrane, with a deviation angle of 5°-85°, and the deviation angle of the central axis of the first through hole is different from that of the central axis of the second through hole.

6. The lithium-ion battery according to claim 5, characterized in that, The first through hole and the second through hole may have the same or different diameters.

7. The lithium-ion battery according to claim 5, characterized in that, The first solid electrolyte membrane includes an inorganic solid electrolyte, and the second solid electrolyte membrane includes a polymer solid electrolyte.

8. The method for preparing a lithium-ion battery according to any one of claims 1-7, characterized in that, The method includes: Step S1. The first solid electrolyte membrane is obtained by mixing an inorganic solid electrolyte with a binder and forming a film. Step S2. Coat and dry the polymer solution prepared with the polymer solid electrolyte to obtain the second solid electrolyte membrane precursor; Step S3. Drill holes in the second solid electrolyte membrane precursor obtained in step S2 to obtain multiple first through holes, and fill the multiple first through holes with positive electrode lithium replenishing agent to obtain the second solid electrolyte membrane; Step S4. Provide a positive electrode and a negative electrode, and stack the positive electrode, the second solid electrolyte membrane, the first solid electrolyte membrane and the negative electrode in sequence and press them to obtain the lithium-ion battery.

9. The method for preparing a lithium-ion battery according to claim 8, characterized in that, The preparation method further includes step S3.5: perforating the second solid electrolyte membrane obtained in step S3 to obtain a plurality of second through holes, and filling the plurality of second through holes with solid electrolyte particles.

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