Battery and preparation method therefor, and electrical apparatus

Abstract

A battery, comprising a negative electrode, a positive electrode, and an ion-conducting layer. The ion-conducting layer is located between the negative electrode and the positive electrode, and a lithium replenishment layer is provided on the side of the ion-conducting layer facing the negative electrode. The negative electrode comprises a current collector and a lithiophilic transition layer provided on a surface of the current collector. The lithiophilic transition layer comprises a lithiophilic element capable of forming an alloy with lithium. In addition, the present application further relates to a preparation method for the described battery and an electrical apparatus comprising the described battery. The battery has high cycle performance and safety performance, and can overcome the problem of lithium dendrites caused by uneven deposition of lithium metal in existing copper-based lithium negative electrodes.

Description

A battery and its preparation method, and an electrical device thereof.

[0001] This application claims priority to Chinese Patent Application No. 202510021836.8, filed on January 6, 2025, entitled “A Battery and its Preparation Method and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of battery technology, specifically relating to a battery and its preparation method, and an electrical device thereof. Background Technology

[0003] The current energy density of lithium-ion batteries has reached 300 Wh / kg, while the theoretical energy density of lithium batteries with silicon-carbon anodes is approximately 350 Wh / kg. How to further improve battery energy density has become a research focus for both academia and industry. Compared to the theoretical specific capacity of graphite anodes (372 mAh / g), lithium metal boasts an ultra-high theoretical specific capacity of 3860 mAh / g and the most negative standard reduction potential (-3.04 V). It also features low density and small ionic radius, making it an ideal anode material for ultra-high battery energy density (500 Wh / kg). However, lithium metal exhibits drastically different electrochemical and mechanical properties in batteries compared to graphite anodes, due to its extremely high reduction activity, significant volume changes during cycling, and the problem of lithium dendrite growth on the anode surface. The widespread application of liquid and solid-state lithium metal anode systems faces these pressing technical challenges.

[0004] The existing negative electrode current collectors generally use copper-based materials. However, the affinity between copper-based materials and lithium metal is insufficient, which makes it difficult to composite copper-based current collectors and lithium foil. Furthermore, if wrinkles or waves appear on the surface of the copper-based current collector, it can easily lead to uneven deposition of lithium metal, forming lithium dendrites and piercing the separator. Summary of the Invention

[0005] To address the problem of uneven lithium metal deposition leading to lithium dendrites in existing copper-based lithium anodes, this application provides a battery, its preparation method, and an electrical device thereof.

[0006] The technical solution adopted in this application to solve the above-mentioned technical problems is as follows:

[0007] On one hand, this application provides a battery including a negative electrode, a positive electrode and an ion-conducting layer, wherein the ion-conducting layer is located between the negative electrode and the positive electrode, and a lithium replenishment layer is disposed on the side of the ion-conducting layer facing the negative electrode. The negative electrode includes a current collector and a lithium-affinity transition layer disposed on the surface of the current collector, wherein the lithium-affinity transition layer includes a lithium-affinity element that can form an alloy with lithium.

[0008] Optionally, the lithiophilic element includes one or more of gold, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, boron, silver, tin, silicon, carbon, phosphorus, and bismuth.

[0009] Optionally, the mass content of the lithiophilic element is 20% to 100% based on the total mass of the lithiophilic transition layer being 100%.

[0010] Optionally, the thickness of the lithiophilic transition layer is 0.3–20 μm.

[0011] Optionally, the lithium-affinity transition layer is provided on both sides of the current collector.

[0012] Optionally, the current collector is selected from copper foil or copper mesh.

[0013] Optionally, the thickness of the current collector is 2 to 12 μm.

[0014] Optionally, the surface roughness of the current collector used to contact the lithiophilic transition layer is Ra0.4-5.0 μm.

[0015] Optionally, a conductive adhesive layer is provided between the current collector and the lithiophilic transition layer.

[0016] Optionally, the lithium replenishment layer comprises metallic lithium.

[0017] Optionally, the lithium replenishment layer is selected from a dense lithium layer or a porous lithium layer, wherein the volume porosity of the porous lithium layer is 2% to 20%.

[0018] Optionally, the mass content of the lithium metal is 50% to 100% based on the total mass of the lithium replenishment layer being 100%.

[0019] Optionally, the thickness of the lithium replenishment layer is 0.5–20 μm.

[0020] Optionally, the ion-conducting layer includes one or more of a membrane, a solid electrolyte, a semi-solid electrolyte, and a gel electrolyte.

[0021] Furthermore, this application provides a method for preparing the battery as described above, comprising the following steps:

[0022] A current collector is provided, and a lithium-loving element that can form an alloy with lithium is coated on the surface of the current collector to form a lithium-loving transition layer, thus obtaining a negative electrode;

[0023] An ion-conducting layer is provided, and a lithium-filling layer is covered on one side of the ion-conducting layer.

[0024] A battery is formed by assembling an ion-conducting layer covered with a lithium replenishment layer, a negative electrode, and a positive electrode, with the side of the ion-conducting layer having the lithium replenishment layer and the side of the negative electrode having the lithium-affinity transition layer facing each other.

[0025] Optionally, the lithiophilic transition layer is prepared by one or more of the following methods: roll forming, melt coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, solution treatment, and electrolysis.

[0026] Optionally, the surface of the current collector is roughened, and the roughening treatment includes one or more of mechanical polishing, chemical etching, laser drilling, and plasma etching.

[0027] Optionally, the lithium replenishment layer is prepared by one or more of the following methods: roll forming, melt coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, solution treatment, and electrolysis.

[0028] In another aspect, this application provides an electrical device, including the battery described above, or the battery prepared by the preparation method described above.

[0029] According to the battery provided in this application, a lithiophilic transition layer containing a lithiophilic element is disposed on the surface of the current collector. The lithiophilic element can form an alloy with lithium ions deposited on the negative electrode surface, which can reduce the Li-ion degradation rate. + The nucleation overpotential induces uniform deposition of lithium metal on the negative electrode side, preventing the formation of lithium dendrites. Furthermore, the lithiophilic transition layer possesses high mechanical strength, which is enhanced by alloying the copper-based alloy negative electrode. On the other hand, to ensure the uniformity of the lithium alloy layer formed between the lithiophilic transition layer and the lithium, this application does not directly composite lithium foil onto the negative electrode. Instead, a lithium replenishment layer is set on the side of the ion-conducting layer facing the negative electrode. During battery formation and charge / discharge cycles, the replenishment layer effectively replenishes lost active lithium. Moreover, the lithium alloy formed between the electrochemically induced lithium metal and the lithiophilic transition layer is more uniform, which is more conducive to the uniform deposition of subsequent lithium metal, further reducing the possibility of lithium dendrite formation and improving the battery's cycle performance and safety. Attached Figure Description

[0030] Figure 1 is a schematic diagram of the battery structure provided in this application.

[0031] Figure 2 is an electron microscope image of the negative electrode in Example 1;

[0032] Figure 3 is the energy dispersive X-ray spectrum of the negative electrode in Example 1;

[0033] Figure 4 is an electron microscope image of the negative electrode in Example 2;

[0034] Figure 5 is the energy dispersive X-ray spectrum of the negative electrode in Example 2.

[0035] The reference numerals in the accompanying drawings are as follows: 1. Ion conduction layer; 2. Negative electrode; 21. Lithophilic transition layer; 22. Current collector; 3. Lithium replenishment layer. Detailed Implementation

[0036] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] Referring to Figure 1, an embodiment of this application provides a battery including a negative electrode 2, a positive electrode, and an ion-conducting layer 1. The ion-conducting layer 1 is located between the negative electrode 2 and the positive electrode. A lithium replenishment layer 3 is disposed on the side of the ion-conducting layer 1 facing the negative electrode 2. The negative electrode 2 includes a current collector 22 and a lithium-loving transition layer 21 disposed on the surface of the current collector 22. The lithium-loving transition layer 21 includes a lithium-loving element that can form an alloy with lithium.

[0038] A lithiophilic transition layer 21 containing lithiophilic elements is disposed on the surface of the current collector 22. The lithiophilic elements can form an alloy with lithium ions deposited on the surface of the negative electrode 2, thereby inducing uniform deposition of lithium metal on the negative electrode side and avoiding the formation of lithium dendrites. The lithiophilic transition layer 21 has high mechanical strength, which is improved by alloying the copper-based alloy negative electrode. On the other hand, in order to ensure the uniformity of the formation of the lithium alloy layer between the lithiophilic transition layer 21 and lithium, this application does not directly composite lithium foil on the negative electrode 2, but instead provides a lithium replenishment layer 3 on the side of the ion conduction layer 1 facing the negative electrode 2. During the battery formation stage and the battery charge and discharge cycle stage, the lithium replenishment layer 3 can effectively replenish the lost active lithium. Moreover, the lithium alloy formed between the lithium metal deposited by electrochemical induction and the lithiophilic transition layer 21 is more uniform, which is more conducive to the uniform deposition of subsequent lithium metal, further reducing the possibility of lithium dendrite formation and improving the cycle performance and safety performance of the battery.

[0039] In some embodiments, the battery is a lithium-ion battery.

[0040] In some embodiments, the lithiophilic element includes one or more of gold, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, boron, silver, tin, silicon, carbon, phosphorus, and bismuth. In this application, "multiple" refers to two or more elements.

[0041] In some embodiments, the lithiophilic element is selected from elements capable of forming alloys with both copper and lithium.

[0042] When the lithiophilic element is selected from elements that can form alloys with both copper and lithium, it has good affinity for both the current collector 22 and lithium metal. When the lithiophilic transition layer 21 is combined with the current collector 22, the bonding strength between the lithiophilic transition layer 21 and the current collector 22 can be improved.

[0043] In some embodiments, the lithiophilic element is selected from elements that can form alloys with lithium but not with copper.

[0044] When the lithiophilic element is selected from elements that can form alloys with lithium but not with copper, the current collector 22 can be surface-treated to improve the bonding strength between the lithiophilic transition layer 21 and the current collector 22. The surface treatment can be a surface roughening treatment of the current collector 22 or the application of conductive adhesive to the surface of the current collector 22.

[0045] In some embodiments, the mass content of the lithiophilic element is 20% to 100% based on the total mass of the lithiophilic transition layer 21 being 100%.

[0046] In a specific embodiment, with the total mass of the lithiophilic transition layer 21 being 100%, the mass content of the lithiophilic element can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 78%, 80%, 85%, 90%, 95%, or 100%.

[0047] The lithiophilic element can form the lithiophilic transition layer 21 as a pure metal or as an alloy. In other words, the lithiophilic element partially permeates into the current collector 22 to form a permeated lithiophilic transition layer 21. When the lithiophilic transition layer 21 is an alloy or a permeated structure, the concentration of the lithiophilic element gradually increases, decreases, or remains uniform along the direction away from the current collector 22. When the lithiophilic transition layer 21 is an alloy, it can be an alloy of the lithiophilic element and lithium, an alloy of the lithiophilic element and copper, or an alloy of the lithiophilic element and lithium and copper.

[0048] In some embodiments, the thickness of the lithiophilic transition layer 21 is 0.3–20 μm.

[0049] In specific embodiments, the thickness of the lithiophilic transition layer 21 can be 0.3um, 0.6um, 1um, 2um, 5um, 8um, 12um, 15um, 18um or 20um.

[0050] If the thickness of the lithiophilic transition layer 21 is too low, it will be difficult to form a uniform and complete layer on the surface of the current collector 22, making the preparation process more difficult and having a limited effect on improving the uniformity of lithium deposition; if the thickness of the lithiophilic transition layer 21 is too high, since the lithiophilic transition layer 21 itself has a certain mass and does not provide active lithium ions, it will have an adverse effect on improving the energy density of the battery.

[0051] In some embodiments, the lithium-affinity transition layer 21 is provided on both sides of the current collector 22.

[0052] Since existing batteries mostly use multi-layer stacking or winding, both sides of the negative electrode 2 are opposite to the positive electrode through the ion conduction layer 1. By providing the lithium-loving transition layer 21 on both sides of the current collector 22, the uniform deposition of lithium metal on both sides of the negative electrode 2 can be guaranteed.

[0053] In some embodiments, the current collector 22 is a copper-based current collector.

[0054] In some embodiments, the current collector 22 is selected from copper foil or copper mesh.

[0055] In some embodiments, the copper foil is a perforated copper foil with a perforation rate of 10% to 75%.

[0056] In some embodiments, the thickness of the current collector 22 is 2–12 μm.

[0057] In a specific embodiment, the thickness of the current collector 22 can be 2um, 2.5um, 3um, 3.5um, 4um, 4.5um, 5um, 6um, 7um, 8um, 9um, 10um, 11um or 12um.

[0058] If the thickness of the current collector 22 is too low, there will be insufficient mechanical strength, which will easily lead to cracking and wrinkling during the manufacturing process, affecting its electronic conduction. If the thickness of the current collector 22 is too high, it will not be conducive to improving the energy density of the battery, and the material cost will increase.

[0059] In some embodiments, the surface roughness of the current collector 22 in contact with the lithiophilic transition layer 21 is Ra 0.4-5.0 μm.

[0060] Increasing the surface roughness of the current collector 22 helps to improve the bonding strength between the current collector 22 and the lithiophilic transition layer 21.

[0061] In some embodiments, a conductive adhesive layer is provided between the current collector 22 and the lithiophilic transition layer 21.

[0062] The conductive adhesive layer is an adhesive layer containing conductive particles, including one or more of carbon, silver, and gold. The conductive adhesive layer can improve the bonding strength between the current collector 22 and the lithiophilic transition layer 21, and also help to improve the electronic conductivity between the current collector 22 and the lithiophilic transition layer 21.

[0063] In some embodiments, the thickness of the conductive adhesive layer is 0.5–5 μm.

[0064] In some embodiments, the lithium replenishment layer 3 comprises metallic lithium.

[0065] The lithium replenishment layer 3 serves to provide a source for the deposition of lithium metal on the negative electrode 2, and at the same time, it plays a role in replenishing lithium ions during battery cycling. The lithium replenishment layer 3 can be metallic lithium or a lithium-containing alloy. When metallic lithium is used as the lithium replenishment layer 3, it has a high lithium content (close to 100%), which helps to reduce the volume occupied by the lithium replenishment layer 3 and improve the energy density of the battery.

[0066] In some embodiments, the lithium replenishment layer 3 is selected from a dense lithium layer or a porous lithium layer, wherein the volume porosity of the porous lithium layer is 2% to 20%.

[0067] In some embodiments, the mass content of metallic lithium is 50% to 100% based on the total mass of the lithium replenishment layer 3 being 100%.

[0068] In some embodiments, the thickness of the lithium replenishment layer 3 is 0.5 to 20 μm, for example 0.5 μm, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, or 20 μm.

[0069] If the thickness of the lithium replenishment layer 3 is too low, there will be insufficient lithium supply, making it difficult to meet the lithium insertion / extraction amount required for normal battery cycling, resulting in low battery capacity. If the thickness of the lithium replenishment layer 3 is too high, there will be excess lithium content, which is also not conducive to improving battery capacity and will affect the conduction efficiency of lithium ions on the ion conduction layer 1.

[0070] In some embodiments, the ion-conducting layer 1 includes one or more of a membrane, a solid electrolyte, a semi-solid electrolyte, and a gel electrolyte.

[0071] The diaphragm includes at least one of a polymer-based diaphragm and a coated diaphragm.

[0072] The polymer-based membrane includes a thermoplastic polymer porous membrane, which is made of one or more of polyethylene (PE), polypropylene (PP), polyimide (PI), polyamide-imide (PIA), and polyethylene terephthalate (PET).

[0073] The coated diaphragm includes a polymer base film and a functional coating applied to at least one side of the polymer base film.

[0074] The functional coating comprises at least one of the following: alumina (Al2O3), boehmite (AlOOH), zinc oxide (ZnO), zirconium dioxide (ZrO2), titanium dioxide (TiO2), silicon dioxide (SiO2), barium sulfate (BaSO4), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), polymethyl methacrylate (PMMA), polyacrylic acid (PAA), lithium polyacrylate (PAA-Li), polyacrylonitrile (PAN), styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), polyacrylamide (PAM), polyvinyl acetate (PVAc), or polyurethane (PU).

[0075] The solid electrolyte includes one or more of inorganic solid electrolytes, polymer solid electrolytes, and composite solid electrolytes.

[0076] The inorganic solid electrolyte includes at least one of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes; the oxide solid electrolyte includes at least one of NASICON (sodium fast ion conductor) type solid electrolytes, perovskite type solid electrolytes, and garnet type solid electrolytes; the sulfide solid electrolyte includes at least one of Li6PS5X (X = F, Cl, Br, I), Li2S-SiS2, Li2S-P2S5, Li2S-GeS2, Li2S-SiS2-P2S5, Li2S-GeS2-P2S5, Li2S-SnS2-P2S5, and Li2S-AlS2-P2S5; the halide solid electrolyte includes at least one of Li2MnCl4, Li3InCl6, Li2ZnCl4, LiYbF4, LiAlF4, Li3YCl6, Li3BrCl6, and Li6CoCl8.

[0077] The polymer solid electrolyte comprises a polymer matrix, an inorganic filler, and a lithium salt. The polymer matrix comprises at least one of polyethylene oxide, polycarbonate, polytrimethylene carbonate, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoroethylene copolymer, and lithium polyacrylate. The inorganic filler comprises Li. 1.3 Al 0.3 Ti 1.7(PO4)3, lithium lanthanum zirconium oxide, alumina, and a metal-organic framework, wherein the lithium salt includes at least one of LiAsF6, LiPF6, LiClO4, lithium bis(trifluoromethanesulfonate)imide, lithium bis(fluorosulfonylimide)imide, and lithium tetrafluoroborate.

[0078] The semi-solid electrolyte includes the solid electrolyte and the electrolyte solution.

[0079] The gel electrolyte comprises a polymer matrix and an electrolyte, wherein the electrolyte and the polymer matrix form a gel state.

[0080] When the ion-conducting layer 1 is selected from a separator, the battery also includes an electrolyte, and the battery is a liquid electrolyte battery; when the ion-conducting layer 1 is selected from a solid electrolyte, the battery is a solid battery; when the ion-conducting layer 1 is selected from a semi-solid electrolyte, the battery is a semi-solid battery; when the ion-conducting layer 1 is selected from a gel electrolyte, the battery is a gel electrolyte battery.

[0081] The electrolyte comprises lithium salts, solvents, and additives; the solvents include one or more of the following: carbonates (ethylene carbonate EC, propylene carbonate PC, butene carbonate BC, dimethyl carbonate DMC, diethyl carbonate DEC, methyl ethyl carbonate EMC, γ-butyrolactone (BL), ethers (tetrahydrofuran THF, 2-methyl-tetrahydrofuran 2-Me-THF, dimethoxydimethyl ether DMM, 1,2-dimethoxyethane DOL-DME), and nitriles (acetonitrile AN, etc.); the lithium salts include lithium hexafluorophosphate LiPF6, lithium perchlorate LiClO4, lithium tetrafluoroborate LiBF4, lithium hexafluoroarsenate LiAsF6, and other organic lithium salts (such as lithium trifluoromethanesulfonate LiCF3SO, bis(2-methyl-3-methyl-4-methyl-3 ... One or more of the following: lithium trifluoromethanesulfonyl)imide LiTFSI, lithium difluorosulfonylimide LiFSI, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide LiTNFSI, lithium fluorosulfonyl-perfluorobutylsulfonylimide LiFNFSI, lithium bis(oxalato)borate LiBOB, LiN(CF3SO2)2, and LiC(SO2CF3)3; additives include one or more of the following: film-forming additives, conductive additives, flame-retardant additives, overcharge protection additives, additives for controlling the water and HF content in the electrolyte, and general-purpose additives for improving low-temperature performance. They can also be additives for improving the stability of the electrode-electrolyte interface, such as fluoroethylene carbonate FEC and lithium nitrate LiNO3.

[0082] In some embodiments, the positive electrode includes a positive electrode current collector and a positive electrode material layer disposed on the positive electrode current collector, wherein the positive electrode current collector is selected from a metal foil or a composite current collector; the positive electrode material layer includes a positive electrode active material, wherein the positive electrode active material includes lithium nickel cobalt manganese oxide (N... x M y Cz (x+y+z=1), lithium iron manganese phosphate (LiFe) x Mn y One or more of the following: PO4,x+y=1), lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium-rich manganese-based, lithium nickel manganese oxide (LMNO), and lithium vanadium oxide phosphate (Li3V2(PO4)3,LiVOPO4).

[0083] Another embodiment of this application provides a method for preparing the battery as described above, including the following steps:

[0084] A current collector 22 is provided, and a lithium-loving element that can form an alloy with lithium is coated on the surface of the current collector 22 to form a lithium-loving transition layer 21, thereby obtaining a negative electrode 2;

[0085] An ion-conducting layer 1 is provided, and a lithium replenishment layer 3 is covered on one side surface of the ion-conducting layer 1;

[0086] A battery is formed by assembling an ion conduction layer 1 covered with a lithium replenishment layer 3, a negative electrode 2, and a positive electrode, with the side of the ion conduction layer 1 having the lithium replenishment layer 3 and the side of the negative electrode 2 having the lithium-affinity transition layer 21 facing each other.

[0087] In some embodiments, the lithiophilic transition layer 21 is prepared by one or more of the following methods: roll forming, melt coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, solution treatment, and electrolysis.

[0088] When the lithiophilic transition layer 21 is prepared by roll pressing, a metal strip containing lithiophilic elements can be used as the lithiophilic transition layer 21. The lithiophilic transition layer 21 is covered on both sides of the current collector 22, and then the lithiophilic transition layer 21 and the current collector 22 are combined into one by roll pressing.

[0089] When the lithiophilic transition layer 21 is prepared by physical vapor deposition, lithiophilic elements or alloys of lithiophilic elements can be used as the target material, and the lithiophilic transition layer 21 can be directly deposited on the surface of the current collector 22 by magnetron sputtering or vacuum evaporation to form the lithiophilic transition layer 21.

[0090] When performing vacuum evaporation, the target material is heated by resistance heating, electron beam evaporation, high frequency heating, or laser heating.

[0091] When the lithiophilic transition layer 21 is prepared by solution treatment, the lithiophilic element can be reduced to a layer on the surface of the current collector 22 by reduction reaction, for example, a silver layer can be formed on the surface of the current collector 22 by silver mirror reaction.

[0092] When using the electrolysis method, the current collector 22 can be immersed in a salt solution containing a lithiophilic element and connected to the cathode of the electrolytic cell. The lithiophilic element or an alloy of the lithiophilic element is used as the anode for electrolysis to deposit a lithiophilic transition layer 21 on the surface of the current collector 22.

[0093] In some embodiments, the surface of the current collector 22 is roughened, and the roughening treatment includes one or more of mechanical polishing, chemical etching, laser drilling, and plasma etching.

[0094] By roughening the material, the bonding strength between the current collector 22 and the lithiophilic transition layer 21 can be improved, especially when the lithiophilic transition layer 21 does not contain elements that can form alloys with copper.

[0095] In some embodiments, the lithium replenishment layer 3 is prepared by one or more of the following methods: roll forming, melt coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, solution treatment, and electrolysis.

[0096] The preparation of the lithium replenishment layer 3 is somewhat similar to the preparation of the lithium-affinity transition layer 21, and will not be described in detail here.

[0097] Another embodiment of this application provides an electrical device, including the battery described above, or the battery prepared by the preparation method described above.

[0098] The electrical device may be selected from, but is not limited to, electric vehicles, other electric vehicles or tools, electronic products, industrial tools or equipment, energy storage devices, and toys.

[0099] The present application will be further illustrated by the following examples.

[0100] Example 1

[0101] This embodiment illustrates the battery and its preparation method disclosed in this application, and includes the following steps:

[0102] S10: A copper foil with a thickness of 4 μm and a size of 200 mm * 300 mm was placed in the vacuum chamber of a magnetron sputtering equipment. A hollow silver target was used as the sputtering source, with 4 twin targets and a target-to-substrate spacing of 50 mm. Sputtering was performed to obtain a first lithiophilic transition layer with a surface thickness of 2 μm. The substrate was flipped over, and the above steps were repeated to sputter a second lithiophilic transition layer with a surface thickness of 2 μm, thereby obtaining a copper-silver alloy anode. The surface SEM morphology of this material is shown in Figure 2, and the EDS composition is shown in Figure 3.

[0103] S20: Replace the target material with hollow metallic lithium and sputter a lithium replenishment layer with a surface thickness of 10um on the negative electrode side of a 12um PP membrane.

[0104] S30: The copper-silver alloy negative electrode, the separator containing the lithium replenishment layer, and the positive electrode are stacked in sequence, and then encapsulated in aluminum-plastic film, injected with electrolyte, formed, and sealed again to form a battery.

[0105] The negative electrode area measures 60*80mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode area measures 58*78mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode active material is high-nickel ternary NCM811, with an areal capacity of 4mAh / cm³. 2 The electrolyte is 1 mol LiTFSI, 50% DOL (1,3-dioxolane) + 50% DME (ethylene glycol dimethyl ether). The electrolyte injection volume is 2.5 g / Ah; the aluminum-plastic film thickness is 113 μm; there are 5 positive electrode plates and 6 negative electrode plates.

[0106] Example 2

[0107] This embodiment illustrates the battery and its preparation method disclosed in this application, and includes the following steps:

[0108] S10: A copper foil with a thickness of 4 μm and a size of 200 mm * 300 mm was placed in the vacuum chamber of a magnetron sputtering equipment. A hollow tin target was used as the sputtering source, with 4 twin targets and a target-to-substrate spacing of 50 mm. A first lithiophilic transition layer with a surface thickness of 5 μm was obtained by sputtering. The substrate was flipped over, and the above steps were repeated to obtain a second lithiophilic transition layer with a surface thickness of 5 μm. The surface SEM morphology of the copper-tin alloy anode is shown in Figure 4, and the EDS composition is shown in Figure 5.

[0109] S20: Replace the target material with hollow metallic lithium and sputter a lithium replenishment layer with a surface thickness of 10um on the surface of a 12um separator.

[0110] S30: The copper-tin alloy negative electrode, the separator containing the lithium replenishment layer, and the positive electrode are stacked in sequence, and then packaged, injected with electrolyte, formed, and resealed into a battery.

[0111] The negative electrode area measures 60*80mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode area measures 58*78mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode active material is high-nickel ternary NCM811, with an areal capacity of 4mAh / cm³. 2 The electrolyte is 1 mol LiTFSI, 50% DOL (1,3-dioxolane) + 50% DME (ethylene glycol dimethyl ether). The electrolyte injection volume is 2.5 g / Ah; the aluminum-plastic film thickness is 113 μm; there are 5 positive electrode plates and 6 negative electrode plates.

[0112] Example 3

[0113] This embodiment illustrates the battery and its preparation method disclosed in this application, and includes the following steps:

[0114] S10: The surface roughness of a 4µm thick pure copper current collector is improved using plasma cleaning technology. Indium is placed in a crucible and heated to 200°C to obtain molten indium. Indium is moltenly coated onto the first surface of the 4µm thick pure copper current collector to obtain a 5µm thick first lithiophilic transition layer. After the first lithiophilic transition layer is annealed and cooled to solidify, indium is moltenly coated onto the second surface of the pure copper current collector to obtain a 5µm thick second lithiophilic transition layer, which is then annealed and cooled to solidify. This yields a copper-indium alloy anode.

[0115] S20: A 20µm thick lithium metal layer is prepared by rolling on the negative electrode side of a 12µm thick PP separator to obtain a separator with a lithium replenishment layer.

[0116] S30: A battery is assembled from a copper-indium alloy negative electrode, a separator containing a lithium replenishment layer, and a positive electrode sheet.

[0117] The negative electrode area measures 60*80mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode area measures 58*78mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode active material is high-nickel ternary NCM811, with an areal capacity of 4mAh / cm³. 2 The electrolyte is 1 mol LiTFSI, 50% DOL (1,3-dioxolane) + 50% DME (ethylene glycol dimethyl ether). The electrolyte injection volume is 2.5 g / Ah; the aluminum-plastic film thickness is 113 μm; there are 5 positive electrode plates and 6 negative electrode plates.

[0118] Example 4

[0119] This embodiment illustrates the battery and its preparation method disclosed in this application, and includes the following steps:

[0120] S10: The surface roughness of a 4µm thick pure copper current collector is improved using plasma cleaning technology; a 5µm thick silver strip is prepared on the first and second surfaces of the pure copper current collector by roll forming, respectively obtaining a first and second lithiophilic transition layer. This yields an alloy anode.

[0121] S20: Place a 12µm thick PP separator in the vacuum chamber of the vapor deposition equipment, place the lithium ingot in the crucible, and heat the lithium ingot to 180°C using the barrier vaporization method to prepare a 20µm thick lithium replenishment layer on the negative electrode side surface of the separator.

[0122] S30: A battery is assembled from a copper-silver alloy negative electrode, a separator containing a lithium replenishment layer, and a positive electrode sheet.

[0123] The negative electrode area measures 60*80mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode area measures 58*78mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode active material is high-nickel ternary NCM811, with an areal capacity of 4mAh / cm³. 2 The electrolyte is 1 mol LiTFSI, 50% DOL (1,3-dioxolane) + 50% DME (ethylene glycol dimethyl ether). The electrolyte injection volume is 2.5 g / Ah; the aluminum-plastic film thickness is 113 μm; there are 5 positive electrode plates and 6 negative electrode plates.

[0124] Comparative Example 1

[0125] This comparative example is used to illustrate the battery and its preparation method disclosed in this application, including the following steps:

[0126] S10: Lithium metal with a thickness of 20 μm is placed on the first and second surfaces of a 4 μm pure copper current collector, and then composited using a roll forming method to obtain a lithium metal anode.

[0127] S20: Assemble a battery by combining a lithium metal anode, separator, and positive electrode.

[0128] The negative electrode area measures 60*80mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode area measures 58*78mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode active material is high-nickel ternary NCM811, with an areal capacity of 4mAh / cm³. 2 The electrolyte is 1 mol LiTFSI, 50% DOL (1,3-dioxolane) + 50% DME (ethylene glycol dimethyl ether). The electrolyte injection volume is 2.5 g / Ah; the aluminum-plastic film thickness is 113 μm; there are 5 positive electrode plates and 6 negative electrode plates.

[0129] Comparative Example 2

[0130] This comparative example is used to illustrate the battery and its preparation method disclosed in this application, including the following steps:

[0131] S10: Place a 4µm thick copper foil with dimensions of 200mm*300mm in the vacuum chamber of a magnetron sputtering equipment. Use a hollow silver target as the sputtering source, with 4 twin targets and a target-to-substrate spacing of 50mm. Sputter to obtain a first lithiophilic transition layer with a surface thickness of 5µm. Flip the substrate and repeat the above steps to sputter to obtain a second lithiophilic transition layer with a surface thickness of 5µm.

[0132] Based on this, a lithium metal layer with a thickness of 10 μm is rolled onto the surface of the first lithiophilic transition layer and the surface of the second lithiophilic transition layer, thereby obtaining a copper-silver-lithium alloy anode.

[0133] S20: The copper-silver-lithium alloy negative electrode, separator, and positive electrode are stacked in sequence, and then encapsulated in aluminum-plastic film, injected with electrolyte, formed, and resealed to form a battery.

[0134] The negative electrode area measures 60*80mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode area measures 58*78mm, and the tab area measures 10*12mm, with the short side of the electrode connected to the short side of the tab. The positive electrode active material is high-nickel ternary NCM811, with an areal capacity of 4mAh / cm³. 2 The electrolyte is 1 mol LiTFSI, 50% DOL (1,3-dioxolane) + 50% DME (ethylene glycol dimethyl ether). The electrolyte injection volume is 2.5 g / Ah; the aluminum-plastic film thickness is 113 μm; there are 5 positive electrode plates and 6 negative electrode plates.

[0135] Performance testing

[0136] The batteries prepared above were subjected to the following performance tests:

[0137] The battery was subjected to charge-discharge cycles. The battery capacity at the first discharge and the battery capacity at each discharge were recorded. When the battery capacity decreased to 80% of the capacity at the first discharge, the number of battery cycles was recorded.

[0138] The test results are entered into Table 1.

[0139] Table 1

[0140] The comparison of cycle performance between Examples 1-4 and Comparative Example 1 shows that the introduction of the lithiophilic transition layer significantly improves the cycle performance degradation caused by lithium dendrite formation. The combination of an anode with a lithiophilic transition layer and a separator with a lithium replenishment layer reduces the lithium nucleation overpotential, which is beneficial for uniform lithium deposition on the anode side. Simultaneously, the lithium replenishment layer replenishes the active lithium metal consumed during cycling. Therefore, this design significantly improves battery cycle performance.

[0141] The comparison of the cycle performance of Examples 1-4 and Comparative Example 2 shows that, compared with the lithium metal layer prepared on the surface of the negative electrode current collector by the rolling method, the lithium metal prepared on the negative electrode side of the ion conduction layer is more likely to form a uniform deposition on the negative electrode side during formation or charge and discharge, thereby improving the cycle performance of the battery.

[0142] As can be seen from Examples 2-4, under the same current collector and lithium replenishment layer design, different lithium-loving transition layer elements have different effects on improving cycle life. Silver and indium are better than tin as lithium-loving transition layer elements in improving cycle life.

[0143] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery, characterized in that, The device includes a negative electrode, a positive electrode, and an ion-conducting layer. The ion-conducting layer is located between the negative electrode and the positive electrode. A lithium replenishment layer is disposed on the side of the ion-conducting layer facing the negative electrode. The negative electrode includes a current collector and a lithium-affinity transition layer disposed on the surface of the current collector. The lithium-affinity transition layer includes a lithium-affinity element that can form an alloy with lithium.

2. The battery according to claim 1, characterized in that, The lithiophilic elements include one or more of the following: gold, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, boron, silver, tin, silicon, carbon, phosphorus, and bismuth.

3. The battery according to claim 1, characterized in that, With the total mass of the lithiophilic transition layer being 100%, the mass content of the lithiophilic element is 20% to 100%.

4. The battery according to claim 1, characterized in that, The thickness of the lithiophilic transition layer is 0.3–20 μm.

5. The battery according to claim 1, characterized in that, The lithium-affinity transition layer is provided on both sides of the current collector.

6. The battery according to claim 1, characterized in that, The current collector is selected from copper foil or copper mesh.

7. The battery according to claim 1, characterized in that, The thickness of the current collector is 2–12 μm.

8. The battery according to claim 1, characterized in that, The surface roughness of the current collector used to contact the lithiophilic transition layer is Ra 0.4-5.0 μm.

9. The battery according to claim 1, characterized in that, A conductive adhesive layer is disposed between the current collector and the lithiophilic transition layer.

10. The battery according to claim 1, characterized in that, The lithium replenishment layer comprises metallic lithium.

11. The battery according to claim 10, characterized in that, The lithium replenishment layer is selected from dense lithium layers or porous lithium layers, and the volume porosity of the porous lithium layer is 2% to 20%.

12. The battery according to claim 10, characterized in that, With the total mass of the lithium replenishment layer being 100%, the mass content of the metallic lithium is 50% to 100%.

13. The battery according to claim 1, characterized in that, The thickness of the lithium replenishment layer is 0.5–20 μm.

14. The battery according to claim 1, characterized in that, The ion-conducting layer includes one or more of the following: a membrane, a solid electrolyte, a semi-solid electrolyte, and a gel electrolyte.

15. The method for preparing a battery according to any one of claims 1 to 14, characterized in that, The following steps are included: A current collector is provided, and a lithium-loving element that can form an alloy with lithium is coated on the surface of the current collector to form a lithium-loving transition layer, thus obtaining a negative electrode; An ion-conducting layer is provided, and a lithium-filling layer is covered on one side of the ion-conducting layer. A battery is formed by assembling an ion-conducting layer covered with a lithium replenishment layer, a negative electrode, and a positive electrode, with the side of the ion-conducting layer having the lithium replenishment layer and the side of the negative electrode having the lithium-affinity transition layer facing each other.

16. The method for preparing a battery according to claim 15, characterized in that, The lithiophilic transition layer is prepared by one or more of the following methods: roll forming, melt coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, solution treatment, and electrolysis.

17. The method for preparing a battery according to claim 15, characterized in that, The surface of the current collector is roughened, and the roughening treatment includes one or more of mechanical polishing, chemical etching, laser drilling, and plasma etching.

18. The method for preparing a battery according to claim 15, characterized in that, The lithium replenishment layer is prepared by one or more of the following methods: roll forming, melt coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, solution treatment, and electrolysis.

19. An electrical appliance, characterized in that, This includes the battery as described in any one of claims 1 to 14, or the battery prepared by the preparation method as described in any one of claims 13 to 18.

Images