A lithium-ion battery

Abstract

The present invention belongs to the technical field of batteries and discloses a lithium-ion battery, which includes a positive electrode plate and a negative electrode plate. The active material of the positive electrode plate includes lithium cobaltate single crystal, and the active material of the negative electrode plate includes graphite and silicon particles mixed therein. The positive electrode plate further includes a lithium supplement agent, and the lithium supplement agent is Li2NiO2. The mass percentages X1 and Y1 of lithium cobaltate and Li2NiO2 in the positive electrode plate material satisfy: X1 + Y1 ≥ 90%, 0% < Y1 / (X1 + Y1) ≤ 6%. The present invention aims at a battery system with a single crystal lithium cobaltate positive electrode and a silicon-graphite composite negative electrode. By introducing Li2NiO2 as a lithium supplement agent into the lithium cobaltate positive electrode, it can solve the problem of low initial Coulomb efficiency of the negative electrode caused by the silicon-graphite negative electrode and give full play to the advantage of high volume energy density of this system.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a lithium-ion battery. Background Technology

[0002] In recent years, the environmental and fuel economy issues caused by gasoline-powered vehicles have attracted increasing attention, creating an urgent need for green, environmentally friendly, and economical new energy vehicles to alleviate these problems. Lithium-ion batteries, with their advantages of high voltage, high energy density, long cycle life, low self-discharge, and zero pollution, have become an indispensable part of new energy vehicles. As the energy source for new energy vehicles, the driving range of lithium-ion batteries directly determines the user experience; therefore, high volumetric energy density and high reversible specific capacity have always been hot topics in lithium-ion battery research and improvement. Summary of the Invention

[0003] In view of the problems existing in the background art, the object of the present invention is to provide a lithium-ion battery that can make lithium-ion batteries have both high volumetric energy density and high reversible specific capacity.

[0004] To achieve the above objectives, the present invention adopts the following approach.

[0005] A first aspect of the present invention provides a lithium-ion battery, comprising a positive electrode and a negative electrode. The active material of the positive electrode comprises lithium cobalt oxide single crystals, and the active material of the negative electrode comprises graphite and silicon particles mixed therein. The positive electrode further comprises a lithium replenishing agent, wherein the lithium replenishing agent is Li₂NiO₂, and the mass percentages X₁ and Y₁ of lithium cobalt oxide and Li₂NiO₂ in the positive electrode material satisfy: X₁ + Y₁ ≥ 90%, 0%... <Y1 / (X1+Y1)≤6%。

[0006] For the single-crystal lithium cobalt oxide cathode paired with silicon-graphite composite anode battery system, introducing Li2NiO2 as a lithium replenishing agent into the lithium cobalt oxide cathode can solve the problem of low initial coulombic efficiency of the anode caused by silicon-graphite anode, improve the reversible specific capacity of the system, and give full play to the high volumetric energy density of the system.

[0007] Optionally, after the first charge is completed, the mass percentage Z1 of Ni in the positive electrode material satisfies: 0%. <Z1≤2%。

[0008] Optionally, in the positive electrode sheet, the mass percentages X1 and Y1 of lithium cobalt oxide and Li2NiO2 in the positive electrode sheet material satisfy: 2% ≤ Y1 / (X1+Y1) ≤ 3%.

[0009] Optionally, in the positive electrode, the Dv50 of the lithium cobalt oxide single crystal is between 10 μm and 20 μm, and the coating surface density is between 10 mg / cm³. 2 ~40mg / cm 2 .

[0010] Optionally, in the positive electrode, the lithium cobalt oxide single crystal has a Dv50 of 14 μm and a coating surface density of between 25 mg / cm². 2 .

[0011] Optionally, the total capacity Cp of the positive electrode is less than or equal to the total capacity Cn of the negative electrode.

[0012] Optionally, the positive electrode sheet contains polystyrene additives, with an addition percentage of ≤0.4% by mass.

[0013] Optionally, the positive electrode sheet contains polystyrene additives, with an addition percentage of ≤0.2% by mass.

[0014] Optionally, the polystyrene additives include one or more of SBS, SEBS, and MAH-g-PS.

[0015] To address the high density characteristics of single-crystal lithium cobalt oxide, polystyrene-based additives are introduced into the cathode formulation to solve the brittleness problem after cold pressing of the electrode, ensuring that the innermost corner of the high-density cathode will not crack under pressure.

[0016] A second aspect of the present invention provides a battery module comprising the lithium-ion battery of the first aspect of the present invention.

[0017] A third aspect of the present invention provides a battery pack including the battery module of the second aspect of the present invention.

[0018] A fourth aspect of the present invention provides an electrical device comprising at least one selected from the first aspect of the present invention, the second aspect of the present invention, or the third aspect of the present invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a lithium-ion battery according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of a battery module according to one embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of a battery pack according to an embodiment of the present invention;

[0022] Figure 4 yes Figure 3 An exploded view of a battery pack according to an embodiment of the present invention is shown.

[0023] Figure 5 This is a schematic diagram of an electrical device using a lithium-ion battery as a power source according to an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Lithium-ion battery Detailed Implementation

[0026] The embodiments of this application will be described in detail below. These embodiments should not be construed as limiting the scope of this application.

[0027] The present application will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection claimed in this application.

[0028] The lithium-ion battery according to the present invention is described in detail below.

[0029] One embodiment of this application provides a lithium-ion battery, including a positive electrode and a negative electrode. The active material of the positive electrode includes lithium cobalt oxide single crystals, and the active material of the negative electrode includes graphite and silicon particles mixed therein. The positive electrode also includes a lithium replenishing agent, which is Li₂NiO₂. The mass percentages X₁ and Y₁ of lithium cobalt oxide and Li₂NiO₂ in the positive electrode material satisfy: X₁ + Y₁ ≥ 90%, 0%... <Y1 / (X1+Y1)≤6%。

[0030] The volumetric energy density of lithium-ion batteries is closely related to the active materials of their positive and negative electrodes, especially the positive electrode material. Lithium cobalt oxide single-crystal materials, due to their large particle size, can be processed into positive electrode sheets with high compaction density, thus enabling the development of high volumetric energy density cells. When combined with a silicon-graphite anode, lithium cobalt oxide single-crystal positive electrode can achieve even higher volumetric energy density. Since silicon-graphite anodes consume a significant amount of active lithium during the initial film formation, adding a lithium replenishing agent to the positive electrode can improve the reversible specific capacity of the cell, thereby increasing its energy density. Different lithium replenishing agents, due to their different properties, produce varying effects when combined with different systems.

[0031] This application uses lithium-rich metal oxide nickel oxide (Li2NiO2) as a lithium replenishing agent, which features high initial delithiation and low initial efficiency. To address the issue of low initial efficiency of the negative electrode affecting the reversible specific capacity of the full cell, a certain proportion of Li2NiO2 is pre-doped into the positive electrode to compensate for the initial film formation loss at the negative electrode, thereby achieving ideal reversible specific capacity at the full cell level.

[0032] To ensure that the battery cell has a high energy density, the mass percentages X1 and Y1 of the cathode active material lithium cobalt oxide and the lithium supplement Li2NiO2 in the cathode electrode sheet material satisfy: X1 + Y1 ≥ 90%, 0% < Y1 / (X1 + Y1) ≤ 6%.

[0033] Optionally, after the first charge is completed, in the cathode electrode sheet, the mass percentage Z1 of Ni element in the cathode electrode sheet material satisfies: 0% < Z1 ≤ 2%.

[0034] After the first charge, the Li2NiO2 lithium supplement is partially consumed and no longer exists in the cathode electrode sheet in the form of Li2NiO2 but in the form of Ni element. At this time, in the cathode electrode sheet, the mass percentage Z1 of Ni element = Y1(58.69 / (6.941*2 + 58.69 + 15.9994*2) = 0.33*Y1. Since Y1 satisfies 0% < Y1 / (X1 + Y1) ≤ 6%, therefore, the range of Z1 is: 0% < Z1 ≤ 2%.

[0035] Optionally, the mass percentages X1 and Y1 of the cathode active material lithium cobalt oxide and the lithium supplement Li2NiO2 in the cathode electrode sheet material satisfy: 2% ≤ Y1 / (X1 + Y1) ≤ 3%.

[0036] Since the first efficiency of Li2NiO2 is low, adding too much will reduce the reversible specific capacity level of the battery cell level. Combining the measured data, the addition amount of the lithium supplement Li2NiO2 is preferably: 2% ≤ Y1 / (X1 + Y1) ≤ 3%. At this time, the range of Z1 is: 0% < Z1 ≤ 1%.

[0037] Optionally, in the cathode electrode sheet, the Dv50 of the lithium cobalt oxide single crystal is between 10 μm and 20 μm, and the coating surface density is between 10 mg / cm 2 -40 mg / cm 2 .

[0038] To give full play to the advantage of high volumetric energy density of the battery cell when lithium cobalt oxide is used as the cathode material, the cathode needs to adopt a high coating weight and high compaction density design. In order to meet the high compaction density, large-sized lithium cobalt oxide single crystal particles need to be used.

[0039] Optionally, the total capacity Cp of the cathode electrode sheet is less than or equal to the total capacity Cn of the anode electrode sheet.

[0040] In order to prevent lithium metal from plating out during the first charge of the battery cell, the total capacity Cn of the anode electrode sheet needs to be greater than the total capacity Cp of the cathode electrode sheet.

[0041] Optionally, both the cathode electrode sheet and the anode electrode sheet contain conductive additives.

[0042] Optionally, the positive electrode sheet contains polystyrene additives, with an addition percentage of ≤0.4% by mass.

[0043] Optionally, the positive electrode sheet contains polystyrene additives, with an addition percentage of ≤0.2% by mass.

[0044] Optionally, the polystyrene additives include one or more of SBS, SEBS, and MAH-g-PS.

[0045] In order to ensure that the brittleness of the positive electrode meets the requirements under high pressure and density, that is, the electrode does not crack under pressure, an appropriate amount of polystyrene additives are added to the positive electrode to improve the toughness of the electrode.

[0046] In the lithium-ion battery of the present invention:

[0047] The particle size Dv50 of the positive electrode active material can be measured using a laser diffraction particle size distribution measuring instrument (Mastersizer3000) according to the particle size distribution laser diffraction method (see GB / T19077-2016 for details). The average particle size is expressed as the median value Dv50 of the volume distribution.

[0048] In the lithium-ion battery of the present invention, the type of separator is not specifically limited and can be any separator material used in existing batteries, such as polyethylene, polypropylene, polyvinylidene fluoride and their multilayer composite films, but not limited to these.

[0049] In the lithium-ion battery of the present invention, the electrolyte includes a lithium salt and an organic solvent. The specific types and compositions of the lithium salt and organic solvent are not specifically limited and can be selected according to actual needs. Preferably, the lithium salt can be selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium perchlorate, and the organic solvent can include one or more of cyclic carbonates, chain carbonates, and carboxylic acid esters. The electrolyte may also contain functional additives, such as vinylene carbonate, vinyl sulfate, propanesulfonate lactone, and fluoroethylene carbonate.

[0050] The present application will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0051] First series of embodiments and comparative examples

[0052] (1) Preparation of positive electrode slurry

[0053] The cathode material used was a 14μm Dv50 lithium cobalt oxide single crystal. The specific formulation consisted of lithium cobalt oxide (LCO), conductive carbon black (SP), carbon nanotubes (CNTs), and PVDF mixed in a ratio of 98:0.5:0.5:1. After adding N-methylpyrrolidone solvent and stirring, a cathode slurry with a solid content of 70% was formed. This group served as a standard control group and is designated as Group 1-1. Batteries prepared using this cathode slurry are designated as Comparative Example 1.

[0054] Based on the standard cathode formulation, 2%, 3%, 6%, and 9% by mass of Li2NiO2 were added to the active material to form cathode slurries with a solid content of 70%, designated as Groups 1-2 to 1-5, with corresponding formulations as follows:

[0055] Group 1-2: LCO:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 96.04:1.96:0.5:0.5:1;

[0056] Groups 1-3: LCO:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 95.06:2.94:0.5:0.5:1;

[0057] Groups 1-4: LCO:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 92.12:5.88:0.5:0.5:1;

[0058] Groups 1-5: LCO:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 89.18:8.82:0.5:0.5:1.

[0059] The batteries prepared using the above formula are respectively referred to as Example 1, Example 2, Example 3, and Comparative Example 2.

[0060] In contrast, further preparations were made using ultra-high nickel materials (Ni96, LiNi). 0.93 Co 0.06 Mn 0.01 The positive electrode slurry, with O2 as the main material, is used as an example.

[0061] The cathode material uses a combination of single-crystal and polycrystalline Ni96. Specifically, the formulation consists of Ni96, conductive carbon black (SP), carbon nanotubes (CNTs), and PVDF mixed in a ratio of 97.5:0.8:0.7:1. After adding N-methylpyrrolidone solvent and stirring, a cathode slurry with a solid content of 70% is formed. This group serves as a standard control group and is designated as Group 2-1. Batteries prepared using this cathode slurry are designated as Comparative Example 3.

[0062] Based on the standard cathode formulation, Li2NiO2 with mass fractions of 2%, 3%, 6%, and 9% were added respectively to form cathode slurries with a solid content of 70%, designated as groups 2-2 to 2-5, with corresponding formulations as follows:

[0063] Group 2-2: Ni96:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 95.55:1.95:0.8:0.7:1;

[0064] Group 2-3: Ni96:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 94.57:2.93:0.8:0.7:1;

[0065] Groups 2-4: Ni96:Li2NiO2:Conductive carbon black (SP):Carbon nanotubes (CNT):PVDF = 91.65:5.85:0.8:0.7:1;

[0066] Groups 2-5: Ni96: Li2NiO2: Conductive carbon black (SP): Carbon nanotubes (CNT): PVDF = 88.73: 8.77: 0.8: 0.7: 1;

[0067] The batteries prepared using the above slurry are respectively designated as Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7.

[0068] (2) Preparation of negative electrode slurry

[0069] Graphite, silicon particles, negative electrode conductive carbon black (SP), and styrene-butadiene rubber are mixed together in a ratio of 72:24:1:3. After adding deionized water as a solvent and stirring, a negative electrode slurry with a solid content of 55% is formed.

[0070] (3) Preparation of positive electrode sheet

[0071] The positive electrode current collector uses aluminum foil with a coating width of 70 mm and a coating surface density of 25 mg / cm³. 2 The coating is applied to one side, and after drying and rolling, the desired positive electrode sheet is obtained.

[0072] (4) Preparation of negative electrode sheet

[0073] The negative electrode current collector uses copper foil with a coating width of 75 mm and a coating surface density of 8 mg / cm³. 2 8.2 mg / cm 2 8.3 mg / cm 2 8.6 mg / cm 2 8.8 mg / cm 2 The coating is applied to both sides, and after drying and rolling, a negative electrode sheet with uniform thickness is obtained.

[0074] Since the proportion of lithium cobalt oxide in the positive electrode is different in each group, different negative electrode coating surface densities are designed to achieve the same positive and negative electrode capacity ratio, thus achieving a better control.

[0075] In contrast, a negative electrode sheet for a battery using Ni96 material as the main positive electrode material was further prepared.

[0076] The negative electrode current collector uses copper foil with a coating width of 75 mm and a coating surface density of 10.5 mg / cm³. 2 10.6 mg / cm 2 10.7 mg / cm 2 10.8 mg / cm 2 10.9 mg / cm 2 The coating is applied to both sides, and after drying and rolling, a negative electrode sheet with uniform thickness is obtained.

[0077] For the same reason, since the proportion of Ni96 in the positive electrode is different in each group, different negative electrode coating surface densities are designed to achieve the same positive and negative electrode capacity ratio, thus achieving a better control.

[0078] (5) Preparation of electrolyte

[0079] Ethylene carbonate and diethyl carbonate were mixed in a mass ratio of 3:7, and lithium hexafluorophosphate (LiPF6) was added in the corresponding proportion. After being fully dissolved, a 1 mol / L LiPF6 electrolyte solution was prepared as the standard electrolyte.

[0080] (6) Preparation of the separating membrane

[0081] A 12μm thick polypropylene membrane was selected as the separator.

[0082] (7) Fabrication of laminated cells

[0083] Take the above-mentioned positive electrode, negative electrode and separator respectively, and assemble them in the order of single-sided positive electrode-separator-double-sided negative electrode-separator-single-sided positive electrode. Then weld the electrode tabs, put in the aluminum-plastic film to assemble into a stacked cell, inject standard electrolyte, and after the first charge activation, the stacked cell is completed.

[0084] The performance testing of lithium-ion batteries will be explained next.

[0085] After the laminated battery cells are assembled, charge-discharge tests are carried out at a rate of 0.33C at 25°C. The voltage range of the battery cells is: for the lithium cobaltate group, it is 2.5 - 4.5V. The actual lithium supplementation effect is judged by calculating the first charge and discharge specific capacities of the battery cells with different addition amounts of Li2NiO2. The first charge specific capacity depends on the amount of lithium deintercalated from the positive electrode, and the first discharge specific capacity is the reversible specific capacity. Then, the actual volumetric energy density of the battery cells is calculated by actual discharge energy / battery cell volume. As shown in Table 1.

[0086] Table 1 Electrical properties of laminated battery cells with different addition amounts of Li2NiO2

[0087]

[0088]

[0089] As shown in Table 1, comparing Comparative Example 1, Example 1, Example 2, Example 3 and Comparative Example 2, as the addition amount of Li2NiO2 increases from 0% to 9%, the amount of lithium deintercalated from the positive electrode continuously increases. Based on the amount of lithium deintercalated from the positive electrode in Comparative Example 1, the amounts of lithium deintercalated from the positive electrodes in Example 1, Example 2, Example 3 and Comparative Example 2 increase by 2.3%, 3.6%, 6.8% and 10.2% in sequence.

[0090] Generally speaking, under the condition of the same addition amount of Li2NiO2, the higher the amount of lithium deintercalated from the positive electrode, the greater the amount of lithium deintercalated from Li2NiO2, the better the supplementary effect on the lithium loss during the first film formation of the negative electrode, the more significant the improvement effect on the reversible specific capacity of the full battery, and at the same time, the more obvious the increase in the volumetric energy density.

[0091] However, due to the low first efficiency of Li2NiO2, adding too much will reduce the reversible specific capacity level and volumetric energy density at the battery cell level. For example, although the reversible specific capacity of Example 3 increases by 1.7%, the volumetric energy density slightly decreases by 0.8%. In addition, the reversible specific capacity and volumetric energy density of Comparative Example 2 decrease by 0.2% and 3.9% respectively. According to the measured data, the optional range of the addition amount of Li2NiO2 is: 0% < Y1 / (X1 + Y1) ≤ 6%. The preferred range is: 2% ≤ Y1 / (X1 + Y1) ≤ 3%.

[0092] As a comparison, although using a high-nickel cathode material as the cathode material can also achieve a high volumetric energy density of the battery, the effect of using Li2NiO2 as a lithium supplement agent in this system is not ideal.

[0093] As shown in Table 1, comparing Examples 1-3 and Comparative Examples 4-6, it can be seen that using the lithium supplementer Li2NiO2 in the lithium cobalt oxide system is more effective. For example, adding 3 wt.% Li2NiO2 increases the reversible specific capacity of the lithium cobalt oxide system by 3.5% (see Example 2), while adding 3 wt.% Li2NiO2 increases the reversible specific capacity of the ultra-high nickel system by only 1.9% (see Comparative Example 5), and adding 6 wt.% Li2NiO2 increases the reversible specific capacity of the ultra-high nickel system by only 2.9% (see Comparative Example 6).

[0094] This is because the voltage range used by the lithium cobalt oxide (LCO) system (2.5V-4.5V) is higher than that of the ultra-high nickel (Ni96) system (2.5V-4.25V). Therefore, when adding the same mass percentage of Li2NiO2, more lithium ions are released from Li2NiO2 in the lithium cobalt oxide system, resulting in a better replenishment effect for lithium ions consumed during negative electrode film formation. Simultaneously, thanks to the higher voltage plateau and higher compaction density of the lithium cobalt oxide system, the addition of Li2NiO2 leads to a greater increase in the volumetric energy density of the lithium cobalt oxide system.

[0095] Second Embodiment Series

[0096] The cathode material still uses lithium cobalt oxide (LCO) single crystals. After adding Li₂NiO₂, it is mixed in a ratio of LCO:Li₂NiO₂:conductive carbon black (SP):carbon nanotubes (CNT):PVDF = 95.06:2.94:0.5:0.5:1. After adding N-methylpyrrolidone solvent and stirring, a cathode slurry with a solid content of 70% is formed. This group serves as a standard control group, designated as Group 1-3, which is Example 2 in the first embodiment series.

[0097] Based on lithium cobalt oxide groups 1-3, SEBS with mass fractions of 0.1%, 0.2%, and 0.4% were added respectively, corresponding to a (lithium cobalt oxide + Li2NiO2) mass percentage of 97.9%, 97.8%, and 97.6%, respectively, forming a positive electrode slurry with a solid content of 70%, which were designated as groups 3-2, 3-3, and 3-4, respectively. The prepared positive electrode sheets were designated as Examples 4, 5, and 6, respectively.

[0098] After the above slurry is prepared, it is coated onto the surface of a 13µm aluminum foil, with a coating density of 25mg / cm². 2 The material is coated on both sides, dried, and rolled to obtain the desired positive electrode sheet. The prepared sample was rolled once using a 2kg cylindrical roller, then folded in half to collect its brittleness. The test results are shown in Table 2.

[0099] Table 2. Results of electrode brittleness test after adding polystyrene additives.

[0100] Example or comparative example number Slurry group number Polystyrene additives addition amount / wt.% Number of bends when light passes through Example 2 1-3 0 2 Example 4 3-1 0.1 3 Example 5 3-2 0.2 4 Example 6 3-3 0.4 4

[0101] To achieve high volumetric energy density, this invention employs lithium cobalt oxide single-crystal cathode material. Lithium cobalt oxide single crystals are quite brittle, and are prone to cracking, especially at the innermost corners, during cathode fabrication. Therefore, based on the first series of embodiments, polystyrene-based additives are added to the cathode formulation of the lithium cobalt oxide single-crystal system. This allows for particle slippage under high compaction density, reducing the elongation of the electrode layers.

[0102] Comparing Examples 2, 4, 5, and 6, the number of bends during light transmission increased from 2 to 4 as the amount of polystyrene additives increased. This indicates that the addition of polystyrene additives helps improve the toughness of the positive electrode sheet.

[0103] Comparing Examples 5 and 6, when the amount added reaches 0.2%, the toughness of the positive electrode sheet already meets the requirements. Further increasing the amount of polystyrene additives will reduce the volumetric energy density of the battery.

[0104] This invention does not impose any particular limitation on the shape of the lithium-ion battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a square-structured lithium-ion battery 5.

[0105] In some implementations, lithium-ion batteries can be assembled into battery modules, and the number of lithium-ion batteries contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0106] Figure 2 This is battery module 4, used as an example. (See reference...) Figure 2 In battery module 4, multiple lithium-ion batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple lithium-ion batteries 5 can be fixed in place using fasteners.

[0107] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple lithium-ion batteries 5 are housed.

[0108] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0109] Figure 3 and Figure 4 This is battery pack 1 as an example. (See reference...) Figure 3 and Figure 4The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0110] In addition, this application also provides an electrical device, which includes at least one of the lithium-ion battery, battery module, or battery pack provided in this application. The lithium-ion battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0111] As the electrical device, a lithium-ion battery, battery module, or battery pack can be selected according to its usage requirements.

[0112] Figure 5 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of lithium-ion batteries for this device, a battery pack or battery module can be used.

[0113] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use lithium-ion batteries as their power source.

[0114] The present invention provides a detailed description of a lithium-ion battery and an electrical device. Specific embodiments have been used to illustrate the principles and implementation methods of the invention. These embodiments are merely illustrative of the invention's method and core ideas, including the best mode, and are intended to enable any person skilled in the art to practice the invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the wording of the claims, or if they include equivalent structural elements that are not substantially different from the wording of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A lithium-ion battery, comprising a positive electrode and a negative electrode, wherein the active material of the positive electrode comprises lithium cobalt oxide single crystal, and the active material of the negative electrode comprises graphite and silicon particles mixed therein, characterized in that, The positive electrode also includes a lithium replenishing agent, which is Li₂NiO₂, wherein the mass percentages X₁ and Y₁ of lithium cobalt oxide and Li₂NiO₂ in the positive electrode material satisfy: X₁ + Y₁ ≥ 90%, 0%... <Y1 / (X1+Y1)≤6%。 2. The lithium-ion battery according to claim 1, characterized in that, After the first charge is completed, the mass percentage Z1 of Ni in the positive electrode material satisfies: 0%. <Z1≤2%。 3. The lithium-ion battery according to claim 1, characterized in that, In the positive electrode sheet, the mass percentages X1 and Y1 of lithium cobalt oxide and Li2NiO2 in the positive electrode sheet material satisfy: 2% ≤ Y1 / (X1+Y1) ≤ 3%.

4. The lithium-ion battery according to any one of claims 1 to 3, characterized in that, In the positive electrode, the Dv50 of the lithium cobalt oxide single crystal is between 10 μm and 20 μm, and the coating surface density is between 10 mg / cm³. 2 ~40mg / cm 2 .

5. The lithium-ion battery according to claim 4, characterized in that, In the positive electrode, the lithium cobalt oxide single crystal has a Dv50 of 14 μm and a coating surface density of 25 mg / cm². 2 .

6. The lithium-ion battery according to any one of claims 1 to 3, characterized in that, The total capacity Cp of the positive electrode is less than or equal to the total capacity Cn of the negative electrode.

7. The lithium-ion battery according to any one of claims 1 to 6, characterized in that, The positive electrode sheet contains polystyrene additives, with an addition percentage of ≤0.4% by mass.

8. The lithium-ion battery according to claim 7, characterized in that, The positive electrode sheet contains polystyrene additives, with an addition percentage of ≤0.2% by mass.

9. The lithium-ion battery according to any one of claims 7 or 8, characterized in that, The polystyrene additives include one or more of SBS, SEBS, and MAH-g-PS.

10. A battery module, characterized in that, The lithium-ion battery includes any one of claims 1 to 9.

11. A battery pack, characterized in that, Includes the battery module as described in claim 10.

12. An electrical appliance, characterized in that, It includes at least one selected from the lithium-ion battery of claims 1 to 9, the battery module of claim 10, or the battery pack of claim 11.

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