Lithium ion battery, preparation method thereof and electric device

Abstract

The application discloses a lithium ion battery, a preparation method thereof and an electric device. The lithium ion battery comprises a pole group and a lithium supplement sheet. The pole group comprises a positive electrode sheet, a negative electrode sheet and a diaphragm, and the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet. The lithium supplement sheet comprises a lithium supplement medium, is arranged on one side of the pole group in the thickness direction, and is electrically connected with the positive electrode sheet. According to the lithium ion battery, the lithium supplement sheet is arranged on one side of the pole group in the thickness direction, and the lithium supplement medium of the lithium supplement sheet gradually releases active lithium ions with the increase of formation voltage in the formation stage, thereby providing additional active lithium consumption for long cycle of the pole group, and helping to improve the first coulomb efficiency, actual capacity, energy density and cycle performance of the lithium ion battery. In addition, the gas generated by the lithium supplement sheet in the formation process can be quickly discharged through the negative pressure system of the liquid injection port of the lithium ion battery shell, thereby avoiding the abnormal generation of black spots caused by lithium intercalation of the negative electrode sheet, and reducing the initial discharge capacity.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery, its preparation method, and an electrical device thereof. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage technologies, higher demands are being placed on the cycle performance of lithium-ion batteries. The continuous repair of the SEI (Solid Electrolyte Interphase) film on the surface of the negative electrode particles within the lithium-ion battery electrode assembly constantly consumes the active lithium, which is one of the main reasons for the degradation of lithium-ion battery cycle performance. To address this issue, related technologies often involve adding a lithium replenishing medium to the positive electrode. This medium releases active lithium under the high-voltage environment of the formation stage. However, when the lithium replenishing medium is mixed with the positive electrode, it generates a large amount of gas during the formation stage. After the electrode assembly is hot-pressed, the positive and negative electrodes are tightly bonded, hindering gas escape. When the gas is not released in time, it adsorbs between the positive and negative electrodes, easily causing black spots on the negative electrode and affecting the cycle performance of the lithium-ion battery. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to provide a lithium-ion battery in which the gas generated during the lithium electrode formation process is easily and rapidly discharged through the negative pressure system of the electrolyte inlet of the lithium-ion battery casing, avoiding abnormal lithium intercalation in the negative electrode and the resulting black spots, thereby reducing the initial discharge capacity.

[0004] A lithium-ion battery according to a first aspect of the present invention includes: an electrode assembly, the electrode assembly including a positive electrode, a negative electrode and a separator, the separator being disposed between the positive electrode and the negative electrode; and a lithium replenishing sheet, the lithium replenishing sheet including a lithium replenishing medium, the lithium replenishing sheet being disposed on one side of the electrode assembly in the thickness direction, and the lithium replenishing sheet being electrically connected to the positive electrode.

[0005] According to embodiments of the present invention, a lithium-ion battery with a lithium replenishing sheet disposed on one side of the electrode assembly in the thickness direction allows the lithium replenishing medium of the sheet to gradually release active lithium ions during the formation stage as the formation voltage increases. This provides additional active lithium consumption for long-term cycling of the electrode assembly, helping to improve the initial coulombic efficiency, actual capacity, energy density, and cycle performance of the lithium-ion battery. Furthermore, the gas generated by the lithium replenishing sheet during formation is easily and quickly discharged through the negative pressure system of the electrolyte filling port of the lithium-ion battery casing, preventing abnormal lithium intercalation in the negative electrode and the resulting black spots, thereby reducing the initial discharge capacity.

[0006] According to some embodiments of the present invention, the lithium replenishment sheet includes: a carrier layer, the carrier layer including a first tab and a lithium replenishment region, the first tab being adapted to be connected to the positive tab of the positive electrode sheet; and a lithium replenishment layer disposed in the lithium replenishment region, the lithium replenishment layer including a lithium replenishment medium.

[0007] According to some embodiments of the present invention, the lithium-ion battery further includes a housing, the housing including a housing body and a top cover, the electrode assembly being disposed within the housing body, the top cover being disposed at one axial end of the housing body, and a positive electrode post being provided on the top cover, the first electrode tab and the positive electrode tab being connected to the positive electrode post.

[0008] According to some embodiments of the present invention, the material of the carrier layer is the same as the material of the positive current collector of the positive electrode sheet.

[0009] According to some embodiments of the present invention, the lithium replenishment medium includes at least one of lithium iron pentoxide, lithium nickel dicoxide, lithium peroxide, lithium oxide, lithium manganese oxide, lithium cobalt dicoxide, lithium manganese dicoxide, and lithium phosphide; and / or, the carrier layer includes at least one of an aluminum layer, a nickel layer, a stainless steel layer, a carbon layer, and a titanium layer; and / or, the thickness of the carrier layer is 10 μm to 1000 μm; and / or, the thickness of the lithium replenishment layer is 50 μm to 500 μm; and / or, the thickness of the lithium replenishment sheet is 60 μm to 1500 μm.

[0010] According to some embodiments of the present invention, on one side of the thickness direction of the carrier layer, the area where the lithium replenishment region is disposed is less than or equal to the area of ​​the carrier layer excluding the first tab.

[0011] According to some embodiments of the present invention, in the thickness direction of the carrier layer, the lithium replenishment layer is disposed on the side of the carrier layer away from the electrode assembly.

[0012] According to some embodiments of the present invention, an insulating layer is covered on the other side of the carrier layer in the thickness direction; and / or, the insulating layer is covered on the side of the carrier layer adjacent to the edge of the lithium replenishment layer.

[0013] According to some embodiments of the present invention, the insulating layer comprises at least one of ceramic, alumina and boehmite.

[0014] According to some embodiments of the present invention, the size of the lithium replenishment sheet is consistent with the size of the side surface of the electrode assembly; and / or, the size of the cross-section of the first electrode tab is consistent with the size of the cross-section of the positive electrode tab.

[0015] According to some embodiments of the present invention, the mass of the positive electrode active material of the positive electrode sheet is M, and the mass of the lithium replenishment medium is m, wherein m satisfies: m = (0.5%~10%)M.

[0016] According to some embodiments of the present invention, the number of electrode groups is at least two, wherein at least one of the electrode groups is provided with the lithium replenishment sheet.

[0017] According to some embodiments of the present invention, the lithium replenishment sheet and the electrode assembly are prepared in different environmental spaces.

[0018] According to a second aspect of the present invention, a method for preparing a lithium-ion battery includes the following steps: dispersing a lithium replenishing medium, a conductive agent, and a binder in a solvent in a certain humidity atmosphere, and mixing them to form a lithium replenishing slurry; coating the lithium replenishing slurry onto the lithium replenishing region of a carrier layer to prepare a lithium replenishing sheet; and connecting the first tab of the lithium replenishing sheet to the positive tab of the electrode assembly.

[0019] According to some embodiments of the present invention, the lithium replenishing sheet is provided with an insulating layer except for the first electrode tab and the lithium replenishing region, and the side of the lithium replenishing sheet away from the lithium replenishing region is opposite to the electrode group.

[0020] According to some embodiments of the present invention, the humidity of the humidity atmosphere is less than 2%.

[0021] According to some embodiments of the present invention, the mass ratio of the lithium replenishing medium, the conductive agent, the binder, and the solvent is (94-98.5):(0.5-3.0):(1.0-3.0); and / or, the conductive agent includes at least one selected from Super-P, acetylene black, carbon nanotubes, carbon fibers, and graphene; and / or, the binder includes at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, and polyimide; and / or, the solvent includes N-methylpyrrolidone.

[0022] An electrical device according to a third aspect of the present invention includes: a lithium-ion battery according to the first aspect of the present invention described above; or a lithium-ion battery prepared using the preparation method of the lithium-ion battery according to the second aspect of the present invention described above.

[0023] 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

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of one side of the lithium replenishment sheet in the thickness direction according to an embodiment of the present invention, wherein the first electrode tab is not shown; Figure 2 This is a schematic diagram of the other side of the thickness direction of the lithium replenishment sheet according to an embodiment of the present invention, wherein the first electrode tab is not shown; Figure 3 This is a schematic diagram of a lithium-ion battery according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a lithium replenishment sheet according to an embodiment of the present invention; Figure 5 This is an exploded schematic diagram of the lithium replenishment sheet and electrode assembly according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the attachment of the lithium replenishment sheet and the electrode assembly according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the electrode assembly and top cover of a lithium-ion battery according to an embodiment of the present invention; Figure 8 This is a schematic diagram of a lithium-ion battery assembled according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the assembly of the electrode assembly and top cover of a lithium-ion battery according to a comparative example of the present invention.

[0025] Figure label: 100. Lithium-ion batteries; 1. Electrode assembly; 11. Positive electrode sheet; 111. Positive electrode tab; 2. Lithium replenishment sheet; 21. Carrier layer; 211. First electrode tab; 212. Lithium replenishment area; 22. Lithium replenishment layer; 23. Insulating layer; 3. Shell; 31. Top cover; 311. Positive electrode post; 32. Shell body. Detailed Implementation

[0026] The following is for reference. Figures 1-9 A lithium-ion battery 100 according to an embodiment of the first aspect of the present invention is described.

[0027] like Figures 1-9 As shown, a lithium-ion battery 100 according to a first aspect embodiment of the present invention includes an electrode assembly 1 and a lithium replenishment sheet 2.

[0028] Specifically, electrode assembly 1 includes a positive electrode 11, a negative electrode 11, and a separator, with the separator disposed between the positive electrode 11 and the negative electrode 11. Lithium replenishment sheet 2 includes a lithium replenishment medium, is disposed on one side of electrode assembly 1 in the thickness direction, and is electrically connected to the positive electrode 11.

[0029] For example, in Figure 1 , Figures 4-6 In the example, the lithium replenishing medium in the lithium replenishing sheet 2 can serve as an additional active lithium source to compensate for the irreversible loss of active lithium caused by reactions such as SEI film formation during the first charge and discharge of the lithium-ion battery 100, thereby improving the initial coulombic efficiency and actual capacity of the lithium-ion battery 100. The lithium replenishing medium in the lithium replenishing sheet 2 can directionally release lithium ions during the cycling process of the lithium-ion battery 100, thus improving the cycle life of the lithium-ion battery 100.

[0030] A separator is positioned between the positive and negative electrode plates 11 to isolate them from each other, preventing direct contact and short circuits, while ensuring normal lithium-ion transport between them. The lithium replenishment plate 2 is electrically connected to the positive electrode plate 11 via a conductive path, forming a complete electrochemical circuit and enabling the directional replenishment of active lithium to the negative electrode. The lithium replenishment plate 2 is located on one side of the electrode assembly 1 in the thickness direction, outside the positive and negative electrode plates. During the formation stage, the gas produced by the lithium replenishment plate 2 can be quickly discharged through the negative pressure system of the electrolyte inlet of the lithium-ion battery casing 3, preventing abnormal lithium intercalation in the negative electrode and the formation of black spots. Furthermore, the gas generated by the lithium replenishment plate 2 during charging does not affect the initial discharge capacity of the electrode assembly 1 or the lithium intercalation in the negative electrode, ensuring stable output of the rated capacity during the initial use of the battery.

[0031] According to an embodiment of the present invention, the lithium-ion battery 100, by providing a lithium replenishing sheet 2 on one side of the electrode assembly 1 in the thickness direction, gradually releases active lithium ions in the lithium replenishing medium of the lithium replenishing sheet 2 as the formation voltage increases during the formation stage. This provides additional active lithium consumption for the long-term cycling of the electrode assembly 1, which helps to improve the initial coulombic efficiency, actual capacity, energy density, and cycle performance of the lithium-ion battery 100. In addition, the gas generated by the lithium replenishing sheet 2 during the formation process can be quickly discharged through the negative pressure system of the liquid injection port of the lithium-ion battery 100 casing 3, avoiding abnormal lithium intercalation of the negative electrode sheet and the generation of black spots, thereby reducing the initial discharge capacity.

[0032] According to some embodiments of the present invention, with reference to Figures 1-4 The lithium replenishment sheet 2 includes a carrier layer 21 and a lithium replenishment layer 22. The carrier layer 21 includes a first tab 211 and a lithium replenishment region 212. The first tab 211 is adapted to be connected to the positive tab 111 of the positive electrode sheet 11. The lithium replenishment layer 22 is disposed in the lithium replenishment region 212 and includes a lithium replenishment medium. Since the first tab 211 of the lithium replenishment sheet 2 is welded to the positive tab 111, during the formation stage, the lithium replenishment medium of the lithium replenishment sheet 2 gradually releases active lithium as the formation voltage increases, providing additional active lithium consumption for the long-term cycling of the electrode assembly 1. Specifically, the first tab 211 of the carrier layer 21 is precisely electrically connected and fixed to the positive tab 111 of the positive electrode 11, establishing a conductive path between the lithium replenishment sheet 2 and the positive electrode 11. This provides an electrochemical circuit for the lithium replenishment layer 22 to release lithium ions. Under the action of the electrochemical circuit, the lithium replenishment medium of the lithium replenishment layer 22 releases active lithium, which is conducted through the electrolyte to the interior of the electrode assembly 1 and directionally replenishes the negative electrode, effectively compensating for the loss of active lithium. The carrier layer 21 ensures that the lithium replenishment layer 22 does not shift or fall off during battery assembly and use, ensuring a stable and controllable lithium replenishment process.

[0033] It is important to note that different settings of the lithium replenishment area 212 on the lithium replenishment sheet 2, different areas of lithium replenishment medium, or different thicknesses of the lithium replenishment medium (i.e., the content of lithium replenishment medium) will result in different lithium replenishment effects on the counter electrode assembly 1, and the cycle life will also differ. Furthermore, different types of lithium replenishment medium require different formation voltages to ensure that the lithium replenishment medium can fully release active lithium.

[0034] According to some embodiments of the present invention, with reference to Figure 8 The lithium-ion battery 100 also includes a housing 3, which comprises a housing body 32 and a top cover 31. The electrode assembly 1 is disposed inside the housing body 32, and the top cover 31 is located at one axial end of the housing body 32. A positive electrode post 311 is provided on the top cover 31, and the first electrode tab 211 and the positive electrode tab 111 are both connected to the positive electrode post 311. The housing 3, through the cooperation of the housing body 32 and the top cover 31, fixes the internal electrode assembly 1 and the lithium replenishment sheet 2, preventing displacement or deformation during use, and at the same time isolating external moisture or dust and other foreign objects from entering the lithium-ion battery 100. The positive electrode post 311 is provided on the top cover 31 and connected to the first electrode tab 211 and the positive electrode tab 111, which facilitates the assembly and use of the lithium-ion battery 100 and improves the safety and reliability of lithium-ion batteries. Thus, a stable and low-resistance electrical connection is formed between the positive tab 111 and the positive post 311. While achieving a reliable conductive path, the connection and assembly position design of the first tab 211 and the positive post 311 ensures that the lithium replenishing medium on the lithium replenishing sheet 2 can be precisely positioned on the conductive connection path from the positive post 311 to the positive tab 111. This ensures that the lithium replenishing medium can act uniformly along the current transmission path, without affecting the conductivity stability of the electrode assembly 1, and fully exerting the lithium replenishing effect, thereby improving the initial coulombic efficiency and cycle performance of the lithium-ion battery 100.

[0035] According to some embodiments of the present invention, the material of the carrier layer 21 is the same as the material of the positive current collector of the positive electrode sheet 11. The fact that the carrier layer 21 is made of the same material as the positive current collector improves the interfacial compatibility between the lithium-ion battery sheet 2 and the positive current collector, reducing the contact resistance between them. Simultaneously, using the same material reduces the risk of electrochemical corrosion caused by material differences, improves structural fit and overall stability, thereby improving the charge-discharge performance and cycle life of the lithium-ion battery 100.

[0036] According to some embodiments of the present invention, the lithium replenishment medium includes at least one selected from lithium iron pentoxide (Li5FeO4), lithium nickel dioxide (Li2NiO2), lithium peroxide (Li2O2), lithium oxide (Li2O), lithium manganese oxide (LiMnO2), lithium cobalt hexaoxide (Li6CoO4), lithium manganese hexaoxide (Li6MnO4), and lithium phosphide (Li3P). Lithium iron pentoxide has an anti-fluorite structure, releasing active lithium through stepwise delithiation during charging to compensate for irreversible lithium loss due to the formation of the SEI film on the negative electrode, thereby improving initial efficiency and energy density. Lithium iron pentoxide has a high theoretical specific capacity (approximately 867 mAh / g), requires a small amount, has high lithium replenishment efficiency, low raw material cost, and a simple synthesis process. Lithium nickel dioxide has a layered structure, allowing for reversible insertion and extraction of lithium ions between the nickel and oxygen layers during charging and discharging, resulting in a stable voltage plateau and high specific capacity. The multi-electron redox reaction of nickel improves energy density and provides good rate performance. Lithium peroxide releases lithium and oxygen through electrochemical decomposition, boasting a high theoretical capacity and a thorough lithium release reaction. Furthermore, the product is pure with few side reactions, optimizing interfacial impedance. It exhibits good compatibility in high-voltage systems and has minimal impact on battery cycle stability. Lithium oxide has high ionic conductivity, facilitating rapid lithium-ion transport and reducing interfacial impedance. Lithium ions possess a stable structure, high compaction density, and high volumetric energy density. Its mild side reactions with the electrolyte improve SEI film stability. Lithium manganese oxide has a layered structure, allowing reversible intercalation and deintercalation of lithium ions between lattice layers during charging and discharging, resulting in a stable voltage platform and excellent rate performance. Its unobstructed lithium-ion migration channels and high ionic conductivity effectively reduce interfacial impedance, making it suitable for high-power charging and discharging scenarios. Lithium hexacobalt oxide has a high lithium content and strong lithium replenishment capacity, with sufficient release of active lithium, improving the first-cycle efficiency and energy density of lithium-ion batteries. Lithium hexamanganese oxide has a stable manganese-based framework, excellent thermal stability and safety, long cycle life, and stable voltage output over a wide temperature range. Lithium phosphide can construct a fast lithium-ion transport channel, reduce interfacial impedance, has good chemical stability, and can suppress lithium dendrite growth, thereby improving battery cycle stability and safety. Therefore, the above-mentioned lithium replenishment medium has good compatibility with electrode group 1, fewer side reactions, controllable gas production, and high lithium release efficiency. Using at least one of the above-mentioned lithium replenishment media is beneficial to improving the capacity and cycle stability of the lithium-ion battery 100.

[0037] The carrier layer 21 includes at least one of the following: an aluminum layer, a nickel layer, a stainless steel layer, a carbon layer, and a titanium layer. The aluminum layer has low density, is lightweight, has excellent electrical conductivity, is corrosion-resistant, and is relatively inexpensive. The nickel layer has good electrical and thermal conductivity, strong adhesion, wear resistance, and corrosion resistance. The stainless steel layer has high mechanical strength, is corrosion-resistant, and deformation-resistant, making it suitable for high loads and harsh operating conditions. The carbon layer has high conductivity, low resistance, stable chemical properties, and low contact impedance. The titanium layer has strong corrosion resistance, relatively stable performance, and good environmental adaptability. Therefore, the carrier layer 21 possesses excellent electrical conductivity and mechanical stability, providing reliable structural support and a conductive foundation for the lithium supplement sheet 2.

[0038] The thickness of the carrier layer 21 is 10µm to 1000µm. When the thickness of the carrier layer 21 is less than 10µm, the lithium-ion battery 2 is prone to cracking. When the thickness of the carrier layer 21 is greater than 1000µm, it is not conducive to the cutting and welding of the first tab 211, and it is not conducive to the lightweight and miniaturized design of the lithium-ion battery 100. When the thickness of the carrier layer 21 is limited to the above range, it is beneficial to the structural strength and processing performance of the lithium-ion battery 2, and avoids adverse effects on subsequent cutting and welding processes.

[0039] The thickness of the lithium replenishment layer 22 is 50µm to 500µm. When the thickness of the lithium replenishment layer 22 is less than 50µm, it easily leads to insufficient lithium replenishment medium, which cannot effectively compensate for the loss of active lithium in electrode assembly 1 during the first charge and discharge process. When the thickness of the lithium replenishment layer 22 is greater than 500µm, it easily causes lithium plating inside electrode assembly 1 and exacerbates side reactions. At the same time, it occupies the internal space of lithium-ion battery 100, which is not conducive to the miniaturization design of lithium-ion battery 100. When the thickness of the lithium replenishment layer 22 is limited to the above range, the lithium replenishment function of the lithium replenishment medium is fully utilized, and the first coulombic efficiency of lithium-ion battery 100 is improved.

[0040] The thickness of the lithium replenishment sheet 2 is 60µm to 1500µm. When the thickness of the lithium replenishment sheet 2 is less than 60µm, it cannot provide sufficient space for the carrier layer 21 and the lithium replenishment layer 22, thus failing to fully utilize their respective functions and affecting the lithium replenishment effect of the lithium replenishment sheet 2 on the lithium-ion battery 100. When the thickness of the lithium replenishment sheet 2 is greater than 1500µm, it increases the overall thickness of the lithium-ion battery 100, affecting lithium-ion transport, increasing interface impedance, and causing a mismatch between the lithium replenishment medium input and its effect. When the thickness of the lithium replenishment sheet 2 is limited to the above range, the role of the lithium replenishment medium is fully utilized, improving the energy density of the lithium-ion battery 100.

[0041] According to some specific embodiments of the present invention, such as Figure 1 and Figure 4As shown, on one side of the thickness direction of the carrier layer 21, the area of ​​the lithium replenishment region 212 is less than or equal to the area of ​​the carrier layer 21 excluding the first tab 211. The lithium replenishment region 212 is confined to the effective area on one side of the thickness direction of the carrier layer 21, that is, the area of ​​the lithium replenishment region 212 does not exceed the area of ​​the carrier layer 21 excluding the first tab 211. This ensures a stable contact and reaction interface between the lithium replenishment medium and the interior of the electrode assembly 1, and avoids positional conflicts or contact interference with other components due to the lithium replenishment region 212 being too large. This configuration shortens the lithium release path of the lithium replenishment layer 22, improves the space utilization and assembly adaptability of the lithium replenishment sheet 2, ensures a stable and efficient lithium replenishment process, and does not affect the overall structural layout and electrical connection reliability of the lithium-ion battery 100.

[0042] According to some embodiments of the present invention, with reference to Figure 5 and Figure 6 In the thickness direction of the carrier layer 21, the lithium replenishment layer 22 is disposed on the side of the carrier layer 21 away from the electrode assembly 1. The lithium replenishment layer 22 is disposed on the side of the carrier layer 21 facing outward. The gas generated during the formation stage by the lithium replenishment medium in the lithium replenishment layer 22 can be discharged more quickly, which can effectively avoid the gas from being trapped and accumulated in the positive electrode 11, negative electrode, separator interface and the internal pores of the electrode assembly 1, significantly reducing the risk of electrode assembly 1 swelling and abnormal increase in internal pressure; at the same time, it can reduce the obstruction of electrolyte wetting and ion transport channels by bubbles, ensure that the electrode interface reaction is sufficient and stable, help form a uniform and dense SEI film, thereby improving the initial capacity of the electrode assembly 1, reducing the interface impedance, and improving the cycle stability and safety performance of the battery.

[0043] Meanwhile, the lithium replenishment medium is far away from electrode group 1, so that the lithium replenishment medium has no direct contact with electrode group 1, reducing the risk of side reactions and lithium dendrites, while ensuring the stability of the lithium replenishment path and uniform lithium release, thus improving the 100-cycle stability and safety of the lithium-ion battery.

[0044] According to some embodiments of the present invention, with reference to Figure 2An insulating layer 23 is coated on the other side of the carrier layer 21 in the thickness direction. The insulating layer 23 on the other side of the carrier layer 21 that contacts the electrode assembly 1 forms electrical isolation from the surrounding structure, avoiding the risk of short circuits with surrounding metal components, improving the safety and stability of the lithium-ion battery 100, and reducing the impact of external environment and impurities such as dust on the lithium replenishment sheet 2 and the lithium-ion battery 100. Simultaneously, it helps to fully insulate and separate the lithium replenishment sheet 2 and the negative electrode sheet, avoiding direct electrical contact and micro-short circuits between them, preventing localized high-current discharge, increased self-discharge, and uncontrolled interface side reactions; it also limits the lithium replenishment reaction to proceed orderly mainly at the electrolyte interface and on the surface of the negative electrode active material, allowing lithium ions to be uniformly embedded in the negative electrode sheet, reducing localized lithium plating and edge effects, and improving the consistency of the electrode assembly 1; it also reduces interface impedance fluctuations caused by poor contact, improves the voltage stability and cycle reliability of the electrode assembly 1, and effectively avoids safety hazards such as internal short circuits and thermal runaway of the electrode assembly 1, further improving the overall safety performance and service life of the lithium-ion battery 100.

[0045] An insulating layer 23 is provided on the side of the carrier layer 21 adjacent to the edge of the lithium replenishment layer 22. The insulating layer 23 on the carrier layer 21 adjacent to the lithium replenishment layer 22 helps to further isolate the lithium replenishment layer 22 from the surrounding structure, avoids the risk of short circuit with the surrounding structure, and improves the safety and cycle reliability of the lithium-ion battery 100 while ensuring normal lithium-ion transport.

[0046] Furthermore, the insulating layer 23 includes at least one of ceramic, alumina, and boehmite. Ceramic possesses high insulation performance, high temperature resistance, corrosion resistance, high mechanical strength, strong adhesion, and good flame retardancy, enabling reliable insulation even with a relatively thin layer. Alumina exhibits good chemical stability, resistance to electrolyte corrosion, high hardness, and density, effectively preventing lithium dendrite penetration and internal short circuits. Boehmite, a layered hydrated alumina, provides excellent electrical insulation when used as the insulating layer 23, effectively preventing short circuits and leakage. Furthermore, boehmite exhibits strong chemical stability and resistance to electrolyte corrosion. Therefore, any of the above materials, when used as the insulating layer 23, provides reliable structural support and insulation protection for the lithium replenishment sheet 2 due to its superior insulation performance and chemical stability, thereby improving the safety and long-term stability of the lithium replenishment sheet 2 and the lithium-ion battery 100.

[0047] According to some embodiments of the present invention, with reference to Figures 5-7The size of the lithium replenishment sheet 2 is consistent with the size of the side surface of the electrode assembly 1. The side surface of the electrode assembly 1 is the side adjacent to the lithium replenishment sheet 2. For example, on the side surface in the thickness direction of the carrier layer 21, the height of the area of ​​the lithium replenishment sheet 2 excluding the first tab 211 is consistent with the height of the area of ​​the positive electrode 11 excluding the positive tab 111, and the width of the area of ​​the lithium replenishment sheet 2 excluding the first tab 211 is consistent with the width of the area of ​​the positive electrode 11 excluding the positive tab 111. Thus, the planar dimensions of the lithium replenishment sheet 2 and the side surface of the electrode assembly 1 are completely consistent in size, which helps to ensure the consistency of the lithium replenishment sheet 2 and the positive electrode 11. The lithium replenishment area 212 covers the entire area of ​​the side surface of the electrode assembly 1, ensuring a uniform and full-coverage lithium replenishment effect within the side surface of the electrode assembly 1. This avoids lithium replenishment gaps or local over-lithiation due to size mismatch, thereby ensuring the consistency of lithium replenishment distribution within the electrode assembly 1 and improving the assembly efficiency of the lithium-ion battery 100.

[0048] The cross-sectional dimensions of the first tab 211 are identical to those of the positive tab 111. The identical dimensions of the first tab 211 and the positive tab 111 ensure a stable and reliable conductive contact after assembly, enabling uniform and smooth current transmission. This avoids problems such as localized current concentration and poor contact caused by mismatched contact dimensions, ensuring the effectiveness and stability of the direct conductive connection between the lithium-ion battery 2 and the electrode assembly 1, and improving the safety of the lithium-ion battery 100.

[0049] According to some embodiments of the present invention, the mass of the positive electrode active material of the positive electrode sheet 11 is M, and the mass of the lithium replenishing medium is m, wherein m satisfies: m = (0.5% to 10%)M. The mass of the lithium replenishing medium is limited to 0.5% to 10% of the mass of the positive electrode active material. This ensures the lithium replenishment effect while avoiding problems such as lithium plating and increased side reactions due to excessive lithium replenishing medium, or defects such as low lithium replenishment efficiency and limited capacity recovery due to insufficient lithium replenishing medium. The above-mentioned limitation of the mass relationship between the lithium replenishing medium and the positive electrode active layer enables the effective utilization of the lithium replenishing medium, regulates the lithium release and insertion process, optimizes the electrochemical reaction environment inside the electrode assembly 1, and improves the cycle performance, capacity retention, and safety of the lithium-ion battery 100.

[0050] According to some embodiments of the present invention, the number of electrode groups 1 is at least two, wherein at least one electrode group 1 is provided with a lithium replenishing sheet 2. One lithium replenishing sheet 2 can be provided on one electrode group 1, or lithium replenishing sheets 2 can be provided on both electrode groups 1. The number of electrode groups 1 and lithium replenishing sheets 2 can be set according to the actual usage requirements of the lithium-ion battery 100. Using multiple electrode groups 1 in the lithium-ion battery 100 can reduce internal resistance and improve discharge power.

[0051] According to some embodiments of the present invention, the lithium replenishment sheet 2 and the electrode assembly 1 are prepared in different environmental spaces. The lithium replenishment sheet 2 is manufactured in a separate environmental space, unaffected by the environmental environment of the electrode assembly 1 workshop, and also does not affect the preparation of the electrode assembly 1. For example, since the lithium replenishment medium is prepared in a separate humidity-controlled environmental space, it is unaffected by the humidity of the positive electrode environment, and also does not affect the flow state of the positive electrode slurry. Therefore, by preparing the lithium replenishment sheet 2 and the electrode assembly 1 in different spaces, environmental parameters such as humidity can be strictly controlled in different zones, avoiding mutual interference, effectively reducing the adverse effects of humidity and other parameters on the lithium replenishment sheet 2 or the electrode assembly 1, and improving the stability of the lithium-ion battery 100.

[0052] According to a second aspect of the present invention, a method for preparing a lithium-ion battery 100 includes the following steps: dispersing a lithium replenishing medium, a conductive agent and a binder in a solvent in a certain humidity atmosphere, and mixing them to form a lithium replenishing slurry; coating the lithium replenishing slurry into the lithium replenishing region 212 of the carrier layer 21 to prepare a lithium replenishing sheet 2; and connecting the first tab 211 of the lithium replenishing sheet 2 to the positive tab 111 of the electrode assembly 1.

[0053] First, in an atmosphere with preset humidity, the lithium replenishing medium, conductive agent, and binder are added to a solvent in a preset ratio. After thorough stirring, dispersion, and homogenization, a uniform lithium replenishing slurry is formed. Then, the lithium replenishing slurry is uniformly coated onto the lithium replenishing region 212 of the carrier layer 21 to obtain the lithium replenishing sheet 2. Finally, the first tab 211 of the lithium replenishing sheet 2 is fixed and connected to the positive tab 111 of the electrode assembly 1 by welding, thereby achieving electrical connection between the lithium replenishing sheet 2 and the positive electrode 11.

[0054] According to the method for preparing the lithium-ion battery 100 of the present invention, the method is relatively simple and can efficiently complete the assembly and positioning of the lithium replenishment sheet 2, greatly reducing the difficulty of the lithium replenishment process and the production cost. At the same time, it can ensure that the lithium replenishment sheet 2 is stably positioned and reliably attached inside the electrode assembly 1, providing a good structural basis for the stable release and uniform embedding of lithium ions, and truly achieving efficient, controllable and large-scale lithium replenishment effect, effectively improving the overall yield and production efficiency of the lithium-ion battery 100.

[0055] According to some embodiments of the present invention, the lithium replenishing sheet 2, except for the first tab 211 and the lithium replenishing region 212, is provided with an insulating layer 23. The side of the lithium replenishing sheet 2 away from the lithium replenishing region 212 faces the electrode assembly 1. An insulating layer 23 is also provided at the edge of the lithium replenishing sheet 2. That is, the lithium replenishing sheet 2, except for the lithium replenishing region 212 and the first tab 211, is covered by an insulating layer 23, avoiding the risk of short circuit between the lithium replenishing sheet 2 and surrounding metal parts, and improving the electrical safety of the lithium-ion battery 100. The side of the lithium replenishing sheet 2 away from the lithium replenishing region 212 faces the electrode assembly 1, so that the gas generated by the lithium replenishing medium in the lithium replenishing region 212 during the formation stage can be discharged more quickly, avoiding the accumulation of gas in the gaps inside the electrode assembly 1, increasing the initial capacity of the electrode assembly 1, and improving the cycle stability of the lithium-ion battery 100.

[0056] According to some embodiments of the present invention, the humidity of the ambient atmosphere is less than 2%. During the preparation of the lithium-ion battery 100, setting the humidity atmosphere to below 2% effectively avoids side reactions between moisture in the air and the active components in the lithium replenishment medium, preventing performance degradation of the lithium replenishment medium, failure of active materials, and interface deterioration. Simultaneously, maintaining stable system humidity ensures the uniformity of dispersion, structural stability, and reliability of the lithium replenishment slurry, thus guaranteeing the electrochemical performance of the lithium-ion battery 100. Furthermore, the lithium replenishment sheet 2 is produced in a separate workshop, where environmental humidity is easily controlled, dehumidification energy consumption is low, and production costs are reduced. At the same time, independent production of the lithium replenishment sheet 2 is beneficial for reducing the homogenization and production of the positive electrode sheet 11.

[0057] According to some embodiments of the present invention, the mass ratio of the lithium replenishing medium, conductive agent, binder, and solvent is (94–98.5):(0.5–3.0):(1.0–3.0). Exemplarily, the mass ratio of the lithium replenishing medium, conductive agent, binder, and solvent can be any value or a range of any combination of 94:3:3, 95:2.5:2.5, 96:2:2, 97:1:2, and 98.5:0.5:1. Limiting the mass ratio of the lithium replenishing medium, conductive agent, binder, and solvent to the above range is suitable for fully utilizing the lithium replenishing medium, effectively replenishing the initial irreversible capacity loss, improving the initial capacity of the lithium-ion battery 100, and avoiding the aggravation of side reactions, gas production, and bulging caused by excessive lithium replenishment, thus balancing the capacity utilization, safety, and cycle life of the lithium-ion battery 100.

[0058] The conductive agent includes at least one of Super-P, acetylene black, carbon nanotubes, carbon fibers, and graphene. Super-P has high conductivity and can achieve efficient and stable conductivity at low addition levels, allowing the lithium replenishment medium to fully exert its effect. Acetylene black can construct a stable conductive pathway in the lithium replenishment sheet 2, promoting the full reaction of the lithium replenishment medium. At the same time, acetylene black has good dispersibility and can tightly bind with the lithium replenishment medium, enhancing the structural stability of the lithium replenishment sheet 2, reducing interfacial impedance, and improving the lithium replenishment effect of the lithium replenishment sheet 2. Carbon nanotubes build efficient long-range conductive pathways within the lithium replenishment sheet 2, reducing interfacial impedance. Carbon nanotubes can form a loose and interconnected porous structure, which is conducive to ion transport and ensures that the lithium replenishment medium is fully activated and can stably exert its lithium replenishment effect. Carbon fibers can form an interlocking conductive skeleton inside the lithium replenishment sheet 2, improving the continuity of the overall conductive pathway. The carbon fiber structure has high rigidity, improving the mechanical properties of the lithium replenishment sheet 2 and reducing interlayer cracking and pulverization during hot pressing and cycling. Graphene can quickly construct an efficient planar conductive network, reducing the interfacial impedance of the lithium replenishment layer 22. The layered structure of graphene can form continuous conductive pathways between lithium-ion batteries, thereby increasing ion transport rates. Consequently, this conductive medium allows for uniform release of the lithium-ion battery, reduces interfacial impedance, and improves the rate performance of the lithium-ion battery.

[0059] The binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyimide. PVDF has high bonding strength, effectively binding the lithium replenishment medium, conductive agent, and other powder particles together, thus preventing the lithium replenishment layer 22 from detaching and pulverizing on the carrier layer 21. PTFE exhibits excellent chemical stability, is less prone to side reactions with the lithium replenishment medium, does not hinder lithium-ion transport, and does not affect lithium replenishment efficiency. PTFE also has high mechanical strength and good flexibility, mitigating stress changes in the electrode assembly 1 during processing and cycling, and reducing cracking and detachment of the lithium replenishment layer 22. PTFE does not hinder lithium-ion transport and does not affect the rate performance of the lithium-ion battery 100. Polyimide possesses high high-temperature resistance, chemical stability, and mechanical strength, does not undergo side reactions with the lithium replenishment medium, and has a compact molecular chain structure, reducing structural relaxation and pulverization of the lithium replenishment sheet 2 during cycling. Polyimide does not hinder lithium-ion transport. Therefore, the aforementioned binder improves the adhesion of the lithium replenishment medium and the structural stability of the lithium replenishment sheet 2, prevents the lithium replenishment layer 22 from falling off, and at the same time optimizes interface compatibility, reduces interface impedance, facilitates lithium ion transport, and improves the initial capacity and cycle reliability of the lithium-ion battery 100.

[0060] The solvent includes N-methylpyrrolidone. N-methylpyrrolidone has good wetting and dispersing effects on powders such as lithium-supplementing media and conductive agents, which can make the slurry uniformly dispersed, and N-methylpyrrolidone does not undergo side reactions with lithium-supplementing media.

[0061] Specifically, the preparation method of lithium-ion battery 100 is as follows: (1) In an independent environment with humidity below 2%, the lithium replenishing medium, conductive agent and binder are mixed evenly in a certain proportion and dispersed in N-methylpyrrolidone solvent to obtain lithium replenishing slurry; (2) Calculate the coating density of the above-mentioned lithium replenishment slurry according to the mass of the lithium replenishment medium being 0.5% to 10% of the mass of the positive electrode active material, and then uniformly coat it onto the carrier layer 21 (e.g., Figure 1 As shown), and the other side of the carrier layer 21 (aluminum foil) in the thickness direction is covered with an insulating layer 23 (ceramic insulating coating, such as...). Figure 2 (as shown) (3) Take the electrode assembly 1 that has been wound and hot-pressed, such as Figure 3 As shown. The above-mentioned lithium supplement sheet 2 is arranged as follows... Figure 3 The electrode assembly 1 is cut to the required size to obtain the lithium supplement sheet 2, such as... Figure 4 As shown. The height and width of the lithium supplement sheet 2 are consistent with those of the positive electrode sheet 11, while the first tab 211 is cut and retained for later welding to the positive electrode tab 111; (4) Attach the lithium replenishment area 212 of the lithium replenishment sheet 2 to the outer side of the positive electrode sheet 11, wherein the side of the lithium replenishment sheet 2 coated with the lithium replenishment medium faces outward, such as... Figure 5 and Figure 6 As shown; (5) The first tab 211 of the lithium replenishing sheet 2 and the positive tab 111 are welded to the positive electrode post 311 of the top cover 31 to obtain the electrode assembly 1 with lithium replenishing function, such as Figure 7 As shown; (6) After encapsulating the electrode assembly 1 with polyethylene terephthalate, filling it with electrolyte, and completing the formation process, a lithium-ion battery 100 with lithium replenishment function is obtained, such as... Figure 8 As shown.

[0062] According to a third aspect of the present invention, an electrical device includes: a lithium-ion battery 100 of the first aspect of the present invention described above; or a lithium-ion battery 100 prepared by the preparation method of the lithium-ion battery 100 of the second aspect of the present invention described above.

[0063] According to embodiments of the present invention, the electrical equipment uses the aforementioned lithium-ion battery 100 for power supply. The lithium-ion battery 100, after lithium replenishment optimization, possesses higher initial capacity and more sufficient active lithium compensation, providing the electrical equipment with stronger endurance, reducing the frequency of charging, and meeting the needs of long-term continuous operation. This helps extend the service life of the electrical equipment, significantly improves the overall user experience and performance, and enhances the overall use value and market competitiveness of the equipment.

[0064] This application does not impose any particular restrictions on the electrical devices that use the aforementioned batteries. Exemplary examples include, but are not limited to, mobile phones, laptops, tablets, cameras, televisions, radios, wearable devices (such as smartwatches, smart bracelets, stereo headphones, Bluetooth headsets), electric vehicles (such as new energy vehicles, electric bicycles, etc.), electric toys, backup power supplies, large household energy storage devices, vehicles, aircraft, ferries, computers, energy storage cabinets, etc.

[0065] The embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0066] Example 1: A 588Ah lithium-ion battery with lithium replenishment function specifically includes the following steps: (1) In an environment with a humidity of less than 2%, the lithium replenishing medium Li5FeO4, the conductive agent Super P and the binder PVDF (Polyvinylidene Fluoride) are mixed evenly in a mass ratio of 97:1:2 and dispersed in N-methylpyrrolidone solvent to obtain a lithium replenishing slurry, wherein the mass ratio of the solvent in the lithium replenishing slurry is 30% to 40%; (2) The above-mentioned lithium replenishing slurry is calculated to be 2% of the total positive electrode active material added to the lithium replenishing medium Li5FeO4 occupying group 1. Then, it is uniformly coated on one side of the aluminum foil, and the empty foil edge is coated with a ceramic insulating coating to obtain the lithium replenishing sheet 2. Figure 1 and Figure 2 As shown; (3) Take the electrode assembly 1 after the 588Ah battery cell has been wound and hot-pressed. The thickness of the electrode assembly 1 is 16mm±1mm, the height is 205mm±1mm, the width is 284mm±1mm, the width of the non-curved side of the electrode assembly 1 is 268mm±1mm, and the height of the positive electrode sheet 11 is 197mm±1mm. Cut the above-mentioned lithium supplement sheet 2 into lithium supplement sheets 2 of the same size with a width of 268mm and an effective coating height of 197mm. (4) Attach the foil side of the lithium replenishing sheet 2 to the outer side of the electrode assembly 1, wherein the side of the lithium replenishing sheet 2 with the lithium replenishing medium faces outward, such as... Figure 5 and Figure 6 As shown; (5) The first tab 211 of the lithium replenishment sheet 2 and the positive tab 111 are welded to the positive post 311 of the top cover 31 to obtain a bare cell with lithium replenishment function, such as Figure 7 As shown. This bare cell has four symmetrical electrode groups 1 and two lithium-ion plates 2; (6) After wrapping the bare cell with a polyethylene terephthalate film, inserting it into the casing, injecting electrolyte, and forming, a lithium-ion battery 100 with a thickness of 72.5 mm, a width of 288.0 mm, a height of 216.3 mm, and a capacity of 588 Ah with lithium replenishment function is obtained. Li5FeO4 is used as the lithium replenishment medium, and the formation voltage needs to be charged to 4.1V to fully release the active lithium inside Li5FeO4.

[0067] Example 2: The preparation process in this embodiment is largely the same as in Example 1, except that the lithium replenishment medium is Li2NiO2. The coating density of the lithium replenishment slurry is calculated based on 2% of the total positive electrode active material added to the lithium replenishment medium Li2NiO2 in electrode group 1. As a lithium replenishment medium, Li2NiO2 needs to be charged to 4.0V to release the active lithium inside it.

[0068] Example 3: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 0.5% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0069] Example 4: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 10% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0070] Example 5: The preparation process in this embodiment is largely the same as in Example 1, except that the lithium replenishing medium is Li5FeO4 and Li2NiO2. The lithium replenishing medium Li5FeO4, lithium replenishing medium Li2NiO2, conductive agent Super P, and binder PVDF are mixed in a mass ratio of 77.6:19.4:1:2. The mass ratio of Li5FeO4 to Li2NiO2 is 4:1. The coating density of the lithium replenishing slurry is calculated based on 2% of the total positive electrode active material added to electrode group 1, using lithium replenishing mediums Li5FeO4 and Li2NiO2.

[0071] Example 6: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 3% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0072] Example 7: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 4% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0073] Example 8: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 6% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0074] Example 9: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 8% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0075] Example 10: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 0.3% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupies the electrode group 1.

[0076] Example 11: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 15% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0077] Example 12: The preparation process of this embodiment is roughly the same as that of Example 1, except that the coating density of the lithium replenishment slurry is calculated as 20% of the total positive electrode active material added to the lithium replenishment medium Li5FeO4 occupying electrode group 1.

[0078] Comparative Example 1: The preparation method of a 588Ah lithium-ion battery specifically includes the following steps: (1) Take the electrode group 1 after the 588Ah electrode group is wound and hot-pressed. The thickness of the electrode group 1 is 16mm±1mm, the height is 205mm±1mm, the width is 284mm±1mm, the width of the non-curled side of the electrode group 1 is 268mm±1mm, and the height of the positive electrode 11 is 197mm±1mm. (2) The positive tabs 111 of the four symmetrical electrode groups 1 are welded to the positive terminal 311 of the top cover 31 to obtain a bare cell, such as Figure 9 As shown; (3) After wrapping the bare cell with a polyethylene terephthalate film, inserting it into the casing, injecting liquid, and forming, a lithium-ion battery 100 with a thickness of 72.5 mm, a width of 288.0 mm, a height of 216.3 mm, and a capacity of 588 Ah is obtained.

[0079] The lithium-ion battery 100 does not contain a lithium replenishment medium.

[0080] Comparative Example 2: (1) During the positive electrode homogenization process, lithium replenishment medium Li5FeO4 was added to the positive electrode slurry of the lithium iron phosphate system, and positive electrode sheet 11 was obtained according to the normal process, wherein the mass of Li5FeO4 was 2% of the positive electrode active material; (2) The positive electrode 11, the negative electrode and the separator are wound and hot-pressed to obtain the electrode group 1. The thickness of the electrode group 1 is 16mm±1mm, the height is 205mm±1mm, the width is 284mm±1mm, the width of the non-curled side of the electrode group 1 is 268mm±1mm, and the height of the positive electrode 11 is 197mm±1mm. (3) The positive tabs 111 of the four symmetrical electrode groups 1 are welded to the positive terminal 311 of the top cover 31 to obtain a bare cell, such as Figure 9 As shown; (4) After wrapping the bare cell with a polyethylene terephthalate film, inserting it into the casing, injecting liquid, and forming, a lithium-ion battery 100 with a thickness of 72.5 mm, a width of 288.0 mm, a height of 216.3 mm, and a capacity of 588 Ah is obtained.

[0081] Performance testing (1) Processing of the positive electrode slurry of positive electrode sheet 11 Slurry viscosity: The viscosity of the positive electrode slurry was tested using a rotational viscometer with an RH4# rotor at a speed of 12 rpm at an environment of 25±5℃.

[0082] Whether gelation occurs during homogenization: Take a cup of homogenized positive electrode slurry in a 200ml beaker, let it stand for 12 hours, and observe whether the positive electrode slurry has fluidity. When the positive electrode slurry loses fluidity, it indicates that the positive electrode slurry has gelled.

[0083] Screening during homogenization: Take a 150-mesh steel wire screen to filter the homogenized positive electrode slurry. If the positive electrode slurry is difficult to pass through the screen, it indicates that the particles are agglomerated and difficult to process.

[0084] (2) Fully charged negative electrode (whether black spots appear) Fully charge electrode group 1 and disassemble it to observe whether black spots appear on the surface of the negative electrode.

[0085] (3) Cycle performance test of lithium-ion battery 100 The lithium-ion battery 100 was subjected to constant power charge-discharge at 0.5P in an oven at 25±3℃ to obtain its initial charge and discharge energy. The lithium-ion battery 100 was then continuously cycled at a constant power of 0.5P, and the discharge energy at the 500th and 1000th cycles was recorded. By comparing these values ​​with the initial discharge energy, the energy retention rate of the lithium-ion battery 100 after 500 and 1000 cycles was obtained.

[0086] Table 1 shows the processing of the positive electrode 11 during the homogenization process in the manufacturing process of lithium-ion batteries 100 in Examples 1-12 and Comparative Examples 1-2. Table 2 shows the initial discharge capacity and the state of the fully charged negative electrode. Table 3 shows the room temperature 1C cycle performance of the above schemes.

[0087] Table 1. Processing details during the homogenization process of the positive electrode 11 in the examples and comparative examples.

[0088] Table 2 Initial discharge capacity and fully charged negative electrode state of the examples and comparative examples

[0089] Table 3 Cyclic performance results of the examples and comparative examples

[0090] Test Result Analysis Performance results analysis based on examples and comparative examples: Comparison of the test data from Examples 1-12 and Comparative Examples 1-2 shows that, in the preparation process of the lithium-ion battery 100 with lithium replenishment function, the processing problems such as increased viscosity and abnormal sieving of the lithium replenishment slurry gel caused by the addition of high alkaline lithium replenishment medium during the positive electrode homogenization process are avoided, thereby improving the production efficiency of the lithium-ion battery 100 and the yield of the lithium replenishment sheet 2.

[0091] Comparison of the test data of Examples 1-12 and Comparative Examples 1-2 shows that the lithium replenishment plate 2 of the lithium-ion battery 100 is located on the outside of the electrode assembly 1. During the formation stage, it can quickly discharge the gas produced by the lithium replenishment medium, avoid abnormal lithium intercalation of the negative electrode, reduce the generation of black spots, and improve the initial discharge capacity of the lithium-ion battery 100. Comparison of the test data of Examples 1-12 and Comparative Examples 1-2 shows that the lithium-ion battery 100 with lithium replenishment function can release more active lithium during the cycle, thereby making up for the loss of active lithium in the negative electrode film and improving the cycle performance and life of the lithium-ion battery 100. A comparison of the test data from Examples 1-2, Example 5, and Comparative Examples 1-2 shows that the lithium-ion battery 100 with lithium replenishment function exhibits varying degrees of improvement in cycle performance when using different lithium replenishment media.

[0092] A comparison of the test data from Examples 1, 3, 4, 6-12 and Comparative Examples 1-2 shows that the lithium-ion battery 100 with lithium replenishment function exhibits varying degrees of improvement in cycle performance when different amounts of lithium replenishment medium are added.

[0093] The lithium-ion battery 100, its preparation method, and other components and operations of the electrical device according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0094] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0095] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A lithium-ion battery, characterized in that, include: An electrode assembly, comprising a positive electrode plate, a negative electrode plate, and a separator, wherein the separator is disposed between the positive electrode plate and the negative electrode plate; A lithium replenishing sheet, comprising a lithium replenishing medium, wherein the lithium replenishing sheet is disposed on one side of the electrode assembly in the thickness direction, and wherein the lithium replenishing sheet is electrically connected to the positive electrode sheet.

2. The lithium-ion battery according to claim 1, characterized in that, The lithium supplement sheet includes: The carrier layer includes a first tab and a lithium replenishment region, wherein the first tab is adapted to be connected to the positive tab of the positive electrode sheet; A lithium replenishment layer is disposed in the lithium replenishment region, and the lithium replenishment layer includes a lithium replenishment medium.

3. The lithium-ion battery according to claim 2, characterized in that, It also includes a housing, which includes a housing body and a top cover. The electrode assembly is disposed in the housing body, and the top cover is disposed at one axial end of the housing body. A positive electrode post is provided on the top cover, and the first electrode tab and the positive electrode tab are both connected to the positive electrode post.

4. The lithium-ion battery according to claim 2, characterized in that, The material of the carrier layer is the same as the material of the positive current collector of the positive electrode sheet.

5. The lithium-ion battery according to claim 2, characterized in that, The lithium replenishing medium includes at least one of lithium iron pentoxide, lithium nickel dicoxide, lithium peroxide, lithium oxide, lithium manganese oxide, lithium cobalt dicoxide, lithium manganese dicoxide, and lithium phosphide; and / or, The carrier layer includes at least one of the following: an aluminum layer, a nickel layer, a stainless steel layer, a carbon layer, and a titanium layer; And / or, the thickness of the carrier layer is 10um to 1000um; And / or, the thickness of the lithium replenishment layer is 50µm to 500µm; And / or, the thickness of the lithium replenishment sheet is 60um to 1500um.

6. The lithium-ion battery according to claim 2, characterized in that, On one side of the thickness direction of the carrier layer, the area where the lithium replenishment region is located is less than or equal to the area of ​​the carrier layer excluding the first tab.

7. The lithium-ion battery according to claim 2, characterized in that, In the thickness direction of the carrier layer, the lithium replenishment layer is disposed on the side of the carrier layer away from the electrode assembly.

8. The lithium-ion battery according to claim 7, characterized in that, The other side of the carrier layer in the thickness direction is covered with an insulating layer; and / or, The insulating layer is wrapped around the side of the carrier layer away from the electrode group, near the edge of the lithium replenishment layer.

9. The lithium-ion battery according to claim 8, characterized in that, The insulating layer comprises at least one of ceramic, alumina, and boehmite.

10. The lithium-ion battery according to any one of claims 2-9, characterized in that, The size of the lithium replenishment sheet is consistent with the size of the side surface of the electrode assembly; and / or, The cross-sectional dimensions of the first electrode tab are the same as those of the positive electrode tab.

11. The lithium-ion battery according to any one of claims 1-9, characterized in that, The mass of the positive electrode active material of the positive electrode sheet is M, and the mass of the lithium replenishment medium is m, wherein m satisfies: m = (0.5%~10%)M.

12. The lithium-ion battery according to any one of claims 1-9, characterized in that, The number of electrode groups is at least two, wherein at least one of the electrode groups is provided with the lithium replenishment sheet.

13. The lithium-ion battery according to any one of claims 1-9, characterized in that, The lithium replenishment sheet and the electrode assembly are prepared in different environmental spaces.

14. A method for preparing a lithium-ion battery according to any one of claims 1-13, characterized in that, The process includes the following steps: in a certain humidity atmosphere, dispersing the lithium replenishing medium, conductive agent and binder into a solvent and mixing them to form a lithium replenishing slurry; The lithium replenishing slurry is coated onto the lithium replenishing region of the carrier layer to prepare a lithium replenishing sheet; Connect the first tab of the lithium replenishment sheet to the positive tab of the electrode assembly.

15. The preparation method according to claim 14, characterized in that, The lithium replenishing sheet has an insulating layer on both the first tab and the lithium replenishing area, and the side of the lithium replenishing sheet away from the lithium replenishing area is opposite to the electrode group.

16. The preparation method according to claim 14, characterized in that, The humidity of the aforementioned atmosphere is less than 2%.

17. The preparation method according to claim 14, characterized in that, The mass ratio of the lithium replenishing medium, the conductive agent, the binder, and the solvent is (94–98.5):(0.5–3.0):(1.0–3.0); and / or, The conductive agent includes at least one selected from Super-P, acetylene black, carbon nanotubes, carbon fibers, and graphene; and / or, The adhesive comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, and polyimide; and / or, The solvent includes N-methylpyrrolidone.

18. An electrical appliance, characterized in that, include: The lithium-ion battery according to any one of claims 1-13; Or a lithium-ion battery prepared by any one of claims 14-17.

Images