Battery cell, method of manufacturing and use thereof, and positive electrode material

Abstract

The application relates to the technical field of batteries, and discloses a battery monomer, a preparation method and application thereof, and a positive electrode material. The battery monomer comprises a positive electrode and a negative electrode and an electrolyte arranged between the positive electrode and the negative electrode. In the positive electrode, the positive electrode material comprises a metal oxide of a chemical general formula of LiAxMyDzO2 x M y D Z O2, A is a transition metal element, M and D are doping elements, the doping elements indicated by M include at least one of Mg, Al and B; the doping elements indicated by D include at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo and W, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1. Through the specific doping elements, the application can inhibit the deformation caused by volume expansion and shrinkage of the metal oxide positive electrode material in the process of deintercalating lithium, reduce the overall volume deformation of the positive electrode material, improve the cycle stability, and thus improve the electrochemical performance of the battery monomer.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a battery cell, its preparation method and application, and cathode materials. Background Technology

[0002] Volumetric deformation of metal oxide cathode materials can lead to problems such as active material shedding, increased internal resistance, electrode structure damage, and instability of the SEI (Solid electrolyte interface) layer. These issues significantly and adversely affect the battery's structural stability, electrochemical performance, cycle life, and energy density. In particular, layered transition metal oxide cathode materials undergo anisotropic volumetric deformation during charge and discharge, hindering ion / electron transport and increasing interfacial impedance, thus severely degrading the battery's capacity, cycle life, and other electrochemical properties. Summary of the Invention

[0003] In view of the above problems, this application provides a battery cell, its preparation method and application, and a cathode material to solve the technical problem that the capacity, cycle life and other performance degradation of batteries are caused by the volume deformation of existing metal oxide cathode materials.

[0004] In a first aspect, this application provides a battery cell, including a positive electrode and a negative electrode, and an electrolyte disposed between the positive and negative electrodes, wherein the positive electrode material comprises a material with the general chemical formula LiA. x M y D Z O2 metal oxide, wherein A is a transition metal element, and M and D are dopant elements, wherein the dopant element represented by M includes at least one of Mg, Al, and B; and the dopant element represented by D includes at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, wherein 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

[0005] In this application, the positive electrode material of the battery cell is simultaneously doped with a metal oxide containing at least one of the doping elements indicated by M, including Mg, Al, and B; and at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W. Among these, Mg, Al, and B, being low-valence elements, have valence states and atomic radii close to those of lithium ions in the metal oxide, allowing them to be doped into lithium sites. After being doped into lithium sites, they can provide interlayer support, improving the stability between layers in the metal oxide. Meanwhile, Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, being high-valence metal elements, have valence states and atomic radii close to those of transition metal ions in the metal oxide, allowing them to be doped into transition metal sites. These doped metal elements are non-electrochemically active and do not participate in electron gain or loss during lithium insertion / extraction, resulting in more stable bonding with oxygen. Furthermore, these high-valence elements have stronger electrostatic attraction, leading to stronger bonds with oxygen, which can limit the deformation of the electron cloud around oxygen and improve the stability within the layers of the metal oxide. Furthermore, multi-element synergistic doping regulates the structural order of the cathode material, creating a voltage ramp in the low-voltage region. This allows the cathode material to achieve a relatively considerable capacity at higher doping concentrations, thus improving its capacity. Therefore, this application, through the synergistic effect of specific doping elements, can suppress the deformation caused by volume expansion and contraction of metal oxide cathode materials during lithium insertion / extraction, reducing the overall volume deformation of the cathode material and improving cycle stability. This, in turn, enhances the energy density, cycle life, safety, and other electrochemical performance of the battery cell.

[0006] In some embodiments, the transition metal element represented by A includes at least one of Ni, Co, and Mn. These transition metal oxide cathode materials can achieve multiple valence state transitions through electrochemical reactions, thus exhibiting extremely high electrochemical capacity, which is beneficial for achieving higher energy storage density.

[0007] In some embodiments, the metal oxide has 0.85≤x≤0.97 and 0.03≤y+z≤0.15.

[0008] In some embodiments, the metal oxide contains 0.85 ≤ x ≤ 0.97, 0.005 ≤ y ≤ 0.05, and 0.02 ≤ z ≤ 0.1. With this doping content, the crystal structure of the cathode material can be adjusted through multi-element synergistic doping, acting as a support structure and enhancing the bonding strength between the metal elements and oxygen, thus suppressing volume deformation caused by volume expansion and contraction during lithium insertion / extraction of the metal oxide cathode material.

[0009] In some embodiments, the metal oxide has a layered structure; layered metal oxide cathode materials have significant performance advantages in the field of lithium-ion batteries, exhibiting high specific capacity.

[0010] In some embodiments, the total molar amount of transition metal elements in the metal oxide is 100%, wherein the molar percentage of nickel is not less than 60%. In this case, the metal oxide is a high-nickel cathode material.

[0011] In some embodiments, the outer surface of the metal oxide further has a coating layer, which includes at least one coating material selected from metal oxide, lithium-containing conductor, and conductive polymer. This further improves the stability of the cathode material and reduces its volume deformation.

[0012] In some embodiments, the battery cell is a solid-state battery.

[0013] Secondly, this application provides a method for preparing a battery cell, comprising the following steps:

[0014] Preparation of chemical formula LiA x M y D Z O2 is a metal oxide cathode material, wherein A is a transition metal element, and M and D are dopant elements. The dopant element represented by M includes at least one of Mg, Al, and B; the dopant element represented by D includes at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

[0015] Prepare a positive electrode comprising the aforementioned positive electrode material;

[0016] The positive electrode, negative electrode, and electrolyte are assembled to obtain a battery cell.

[0017] This application describes a method for preparing a negative electrode material with the general chemical formula LiA. x M y D ZAfter preparing the O2 metal oxide cathode material, a cathode containing this material is fabricated and assembled with a negative electrode and electrolyte to form a battery cell 10. The fabrication process is simple and suitable for large-scale industrial production and application. In this metal oxide cathode material, low-valence elements such as Mg, Al, and B can be doped into lithium sites, providing interlayer support and improving the stability between layers in the metal oxide. High-valence metal elements such as Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W can be doped into transition metal sites, strengthening the bond with oxygen and limiting the deformation of the electron cloud around oxygen, thus improving the stability within the metal oxide layers. Furthermore, multi-element synergistic doping regulates the structural order of the cathode material, creating a voltage slope in the low-voltage region, thereby achieving a relatively considerable capacity at higher doping concentrations and increasing the cathode material's capacity. Therefore, by preparing a multi-element doped metal oxide cathode material, the electrochemical performance of the battery cell 10, including energy density, cycle life, and safety, is improved.

[0018] In some embodiments, the method for preparing the metal oxide includes solid-state sintering or co-precipitation.

[0019] In some embodiments, the solid-state sintering method includes the following steps: mixing a transition metal hydroxide precursor with a lithium source and a dopant, followed by sintering in an oxygen-containing atmosphere to obtain the metal oxide. Sintering is then performed at an appropriate temperature and atmosphere to allow diffusion and bonding between powder particles, forming a metal oxide cathode material.

[0020] In some embodiments, the co-precipitation method includes the following steps: preparing a mixed solution containing transition metal ions and dopant ions, adding an alkaline solution and a complexing agent for co-precipitation to obtain a doped hydroxide precursor; calcining the doped hydroxide precursor with a lithium source in an oxygen-containing atmosphere to obtain the metal oxide. A metal hydroxide precipitate is generated through a chemical reaction, and then calcined to obtain a metal oxide cathode material.

[0021] Thirdly, this application provides an electrical device comprising the aforementioned battery cell or a battery cell prepared by the aforementioned method.

[0022] The electrical device provided in this application is based on the battery cell of this application, therefore the electrical device of this application can operate safely and for a long time.

[0023] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application;

[0026] Figure 2 for Figure 1 The diagram shows an exploded view of a single battery cell.

[0027] Figure 3 This is a schematic diagram of one embodiment of the battery module of this application;

[0028] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application;

[0029] Figure 5 for Figure 4 The diagram shows the exploded structure of the battery pack.

[0030] Figure 6 This is a schematic diagram of one embodiment of an electrical device that uses a secondary battery as a power source, as described in the present application.

[0031] Figure 7 X-ray diffraction (XRD) patterns of the metal oxide cathode material in the solid-state battery cell prepared in Example 1 of this application before and after charging;

[0032] Figure 8 This is a scanning electron microscope (SEM) image of the metal oxide cathode material prepared in Example 1 of this application;

[0033] Figure 9 The first charge-discharge curve of the solid-state battery cell prepared in Example 1 of this application;

[0034] Figure 10 Cyclic stability curves of solid-state battery cells prepared in Example 1 and Comparative Example 1 of this application;

[0035] The reference numerals in the detailed embodiments are as follows:

[0036] 10-Battery cell; 11-Housing casing; 12-Top cover assembly; 13-Electrode assembly; 20-Battery module; 30-Battery pack; 31-Upper casing; 32-Lower casing. Detailed Implementation

[0037] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0039] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0040] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0042] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0043] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0044] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0045] Currently, from a market perspective, the volumetric deformation of metal oxide cathode materials leads to problems such as active material shedding, increased internal resistance, electrode structure damage, and instability of the SEI (Solid electrolyte interface) layer. These issues significantly and adversely affect the structural stability, electrochemical performance, cycle life, and energy density of the battery. In particular, layered transition metal oxide cathode materials undergo anisotropic volumetric deformation during charge and discharge, which severely impacts the battery's electrochemical performance. For example, in all-solid-state batteries, high-nickel metal oxide cathode materials undergo anisotropic deformation during lithium removal, characterized by initial expansion followed by contraction along the c-axis and continuous contraction along the a-axis. This results in ineffective contact with the solid electrolyte, hindering ion / electron transport, increasing interfacial impedance, and causing battery performance degradation. These are all key issues preventing their application in all-solid-state batteries.

[0046] To mitigate the volume deformation of metal oxide cathode materials during battery operation, elemental doping and surface coating are commonly employed. However, some technologies involve doping modifications to metal oxide cathode materials. Since the anisotropic deformation of metal oxide cathode materials is an intrinsic property resulting from their crystal and electronic structures, conventional doping strategies are limited by the types and amounts of elements used, thus offering very limited suppression of anisotropic deformation and failing to fundamentally solve the volume deformation problem of metal oxide cathode materials.

[0047] In other technologies, the strategy of coating metal oxide cathode materials has almost no impact on the crystal structure of the electrode material. The coatings used are usually rigid and it is difficult to form a uniform and continuous coating layer. They cannot effectively suppress the deformation of the electrode material and cannot fundamentally solve the electrochemical-mechanical failure problem in the battery.

[0048] Based on the above considerations, in order to address the impact of volume deformation of metal oxide cathode materials on battery capacity, stability, and cycle life during battery operation, this application proposes a battery cell whose cathode material comprises an active material of a metal oxide simultaneously doped with at least one of Mg, Al, and B and at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W.

[0049] In such a battery cell, because the metal oxide in the cathode material is simultaneously doped with specific elements, the bonding strength of the elements in the metal oxide can be enhanced through the synergistic effect of multiple doping elements, thereby improving the structural stability of the cathode material, reducing the anisotropic deformation of the metal oxide cathode material during charging and discharging, and reducing the volume deformation of the cathode material. This improves the structural stability, cycle life, safety, capacity, and other electrochemical performance of the battery cell.

[0050] For ease of understanding, this application is specifically described through the following embodiments. It should be understood that the following embodiments are only used to further illustrate the solution of this application and are not intended to limit the scope of this application.

[0051] battery cell

[0052] In a first aspect, embodiments of this application provide a battery cell 10, such as Figure 1 As shown. In some embodiments, the battery cell 10 includes a positive electrode and a negative electrode, and an electrolyte disposed between the positive and negative electrodes. In the positive electrode, the positive electrode material includes materials with the general chemical formula LiA. x M y D Z O2 is a metal oxide, wherein A is a transition metal element, and M and D are dopant elements. The dopant element represented by M includes at least one of Mg, Al, and B; the dopant element represented by D includes at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

[0053] In the battery cell 10 of this application embodiment, the negative electrode is the electrode with a lower potential in the battery, typically the electrode where oxidation (i.e., losing electrons) occurs in the internal electrochemical reaction of the battery. The positive electrode is the electrode with a higher potential in the battery, typically the electrode where reduction (i.e., receiving electrons) occurs in the internal electrochemical reaction of the battery. The electrolyte in the battery is located between the positive and negative electrodes and plays the role of conducting ions. The positive electrode material in the positive electrode is the positive electrode active material, which refers to the material located on the positive electrode side in the battery that can participate in the electrochemical reaction and provide and receive lithium ions. Metal oxides refer to battery positive electrode materials composed of metal oxides. Among them, the transition metal element shown in A is the intrinsic metal element in the positive electrode material. Transition metal elements include elements from groups 3 to 12 of the periodic table (excluding transition elements in the f block), as well as group IB and group IIB elements with similar properties. These elements are located in the middle region of the periodic table and are also called d-block elements. The dopant element shown in M ​​is not an intrinsic element in the metal oxide cathode material, but an element that is additionally doped into the metal oxide. The doping mentioned here refers to chemical doping at the molecular, lattice, and other chemical levels.

[0054] In this embodiment of the battery cell 10, the positive electrode material is a metal oxide doped with at least one of the doping elements indicated by M, including Mg, Al, and B; and at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W. Among these, Mg, Al, and B, being low-valence elements, have valence states and atomic radii close to those of lithium ions in the metal oxide, allowing them to be doped into lithium sites. After being doped into lithium sites, they can provide interlayer support, improving the stability between layers in the metal oxide. High-valence metal elements such as Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W have valence states and atomic radii close to those of transition metal ions in metal oxides, allowing them to be doped into transition metal sites. These doped metal elements are electrochemically inactive and do not participate in electron gain or loss during lithium insertion / extraction, resulting in more stable bonding with oxygen. Furthermore, these high-valence elements have stronger electrostatic attraction, leading to stronger bonds with oxygen and limiting the deformation of the electron cloud around oxygen, thus improving the stability within the metal oxide layer. Additionally, multi-element synergistic doping regulates the structural order of the cathode material, creating a voltage ramp in the low-voltage region, thereby achieving a relatively considerable capacity at higher doping concentrations and increasing the cathode material's capacity. Therefore, the embodiments of this application, through the synergistic effect of specific doping elements, can suppress the deformation caused by volume expansion and contraction of the metal oxide cathode material during lithium insertion / extraction, reducing the overall volume deformation of the cathode material and improving cycle stability. This, in turn, improves the energy density, cycle life, safety, and other electrochemical performance of the battery cell 10.

[0055] In some possible implementations, Mg, Al, and B are primarily doped at the lithium sites of the metal oxide, and may also be doped in small amounts at the transition metal sites. Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W are primarily doped at the transition metal sites of the metal oxide, and may also be doped in small amounts at the lithium sites. The elements doped at the lithium sites act as interlayer pillars, shielding against the electrostatic repulsion of interlayer oxygen after delithiation. The elements doped at the transition metal sites have strong bonding with oxygen, stabilizing lattice oxygen and reducing lattice size changes caused by valence state changes in the transition metal.

[0056] In some possible implementations, the transition metal element A includes at least one of Ni, Co, and Mn. In this case, the metal oxide can be a multi-component doped lithium nickel oxide, a multi-component doped lithium cobalt oxide, a multi-component doped lithium nickel cobalt manganese oxide, or a multi-component doped lithium nickel manganese oxide. Alternatively, in addition to including at least one of Ni, Co, and Mn, the transition metal element may also include Al. In this case, the metal oxide can be a multi-component doped lithium nickel cobalt aluminum oxide or a multi-component doped lithium nickel manganese aluminum oxide. The electrochemical reactions of these transition metal oxide cathode materials can achieve multiple valence state transitions, thus exhibiting extremely high electrochemical capacity, which is beneficial for achieving higher energy storage density. These transition metal oxide cathode materials have good electronic and ionic conductivity, ensuring good rate performance of the battery. Simultaneously, they have high reaction potentials (typically greater than 2V) and good reversibility, ensuring high output voltage and energy density of the full battery; they can achieve cyclic rechargeability and discharge, thereby fully utilizing their high electrochemical capacity and achieving better energy storage performance.

[0057] In some possible implementations, the metal oxide has a layered structure. Layered metal oxide cathode materials have significant performance advantages in the field of lithium-ion batteries, exhibiting high specific capacity, which can significantly improve battery capacity, thereby achieving longer service life and stronger range. They also have a relatively high voltage plateau, and the increase in voltage further enhances the battery's energy density, and typically possess high chemical stability, resisting electrochemical reactions. This type of cathode material is one of the most important cathodes in commercial applications. However, due to its layered structure, it suffers from significant volume deformation, exhibiting anisotropic deformation during lithium insertion / extraction, characterized by initial expansion followed by contraction along the c-axis (the stacking direction of the layers in the crystal structure) and continuous contraction along the a-axis (the spreading direction of the layers in the crystal structure). The specific element doping schemes in the embodiments of this application have a more significant improvement effect on the anisotropic volume deformation problem of layered transition metal oxide cathode materials during charge and discharge.

[0058] In some embodiments, multiple doping elements in the metal oxide form multi-element (high-entropy) doping. High-entropy doping refers to the introduction of multiple elements into the metal oxide cathode material, where the atomic composition of these doping elements is close to an equimolar ratio, thereby forming a material in a high-entropy state. This doping method can significantly improve the material's performance. Specifically, high-entropy doping can greatly enhance the structural strength of the material by forming a complex chemical bond network and adjusting the configurational entropy within the crystal. High-entropy doping can also improve the conductivity of the cathode material, which is beneficial for lithium-ion migration and transport. Therefore, high-entropy doping can enhance the structural strength of the metal oxide cathode material and improve lithium-ion diffusion kinetics. This results in the cathode material exhibiting excellent structural stability during charge and discharge, reducing the volume deformation of the metal oxide, improving the conductivity of the cathode material, and lowering the formation energy and lithium-ion diffusion barrier, thereby achieving characteristics such as high capacity, excellent rate capability, and excellent cycle performance.

[0059] In this application, multi-element synergistic doping is formed in the metal oxide, which can achieve a high total doping amount, fundamentally changing the evolution characteristics of the electron cloud of the cathode material during the lithium extraction process, stabilizing the crystal structure, thereby achieving low strain and improving the structural stability of the cathode material. In some possible embodiments, in the metal oxide, 0.85≤x≤0.97, 0.03≤y+z≤0.15. In this case, the molar ratio of doping elements y+z in the metal oxide is 0.03~0.15, which includes elements doped at both transition metal sites and lithium sites. With this doping content, the crystal structure of the cathode material can be adjusted through multi-element synergistic doping, acting as a support structure and enhancing the bonding strength between metal elements and oxygen, suppressing volume deformation caused by volume expansion and contraction during lithium insertion and extraction of the metal oxide cathode material, and improving the capacity and cycle stability of the cathode material. Furthermore, this doping content does not affect the intrinsic electrochemical performance of the transition metal oxide.

[0060] In some possible implementations, the metal oxide contains elements with the following valences: 0.85 ≤ x ≤ 0.97, 0.005 ≤ y ≤ 0.05, and 0.02 ≤ z ≤ 0.1. This ensures that low-valence elements such as Mg, Al, and B are doped into lithium sites, providing interlayer support and improving the stability between layers in the metal oxide. Simultaneously, it ensures that high-valence metal elements such as Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W are doped into transition metal sites, increasing the bonding strength with oxygen, better limiting the deformation of the electron cloud around oxygen, and improving the stability within the metal oxide layers.

[0061] For example, in a metal oxide, when the subscript y of dopant element M is 0.005 and the subscript y of dopant element D is 0.025, the subscript x of transition metal A is 0.97. When the subscript y of dopant element M is 0.01 and the subscript y of dopant element D is 0.02, the subscript x of transition metal A is 0.97. When the subscript y of dopant element M is 0.02 and the subscript z of dopant element D is 0.03, the subscript x of transition metal A is 0.95. When the subscript y of dopant element M is 0.03 and the subscript z of dopant element D is 0.05, the subscript x of transition metal A is 0.92. When the subscript y of dopant element M is 0.04 and the subscript z of dopant element D is 0.06, the subscript x of transition metal A is 0.90. When the subscript y of dopant element M is 0.05 and the subscript z of dopant element D is 0.07, the subscript x of transition metal A is 0.88. Similarly, when the subscript y of dopant element M is 0.05 and the subscript z of dopant element D is 0.1, the subscript x of transition metal A is 0.85.

[0062] In some embodiments, the doping element M in the metal oxide includes Mg, Ti, Nb, and Mo. Mg doping in transition metal oxide cathode materials allows for multi-site doping, meaning Mg can be doped not only into traditional transition metal sites but also into lithium sites. This doping method can significantly improve the structural stability of the cathode material, suppress the relative slippage of the transition metal oxide layer, and reduce irreversible structural changes, thereby significantly improving the capacity retention rate after cycling at high cutoff voltages and high current rates. Ti doping in lithium-ion battery cathode materials can improve the energy density, power density, and cycle stability of the cathode material by influencing its structure, electronic conductivity, and ionic conductivity, thus improving the overall performance of the battery. Furthermore, Ti doping can suppress structural changes in the cathode material during charge and discharge, extending the battery's cycle life. In nickel-rich layered oxide cathode materials, Nb doping can improve material performance through surface or bulk lattice modification. In addition, Nb doping can promote radially dense distribution of primary particles, disperse strain, and help stabilize the lattice, protecting it from structural changes. Mo doping can also refine grain size, suppress harmful strain associated with sudden lattice contraction in the high delithiation state, induce partial cation disorder, and stabilize the delithiation structure through the pillar effect. This can improve the cycle stability of the cathode material, allowing it to maintain a high capacity retention rate even after multiple cycles.

[0063] In some possible implementations, the total molar amount of transition metal elements in the metal oxide is 100%, with the molar percentage of nickel being no less than 60%. In this case, the metal oxide is a high-nickel cathode material. Nickel is a metallic element with high specific capacity, so increasing the nickel content in the cathode material can significantly improve the energy density of the battery. Nickel has good electrical conductivity, so cathode materials with high nickel content can more effectively transport electrons and ions, reduce the internal resistance of the battery, and improve the power density and charge / discharge efficiency of the battery.

[0064] In some possible implementations, the cathode material includes LiNi doped with four elements: Mg, Ti, Nb, and Mo. 0.9 Co 0.05 Mn 0.05 O2 ternary cathode material.

[0065] In some possible implementations, the outer surface of the metal oxide also has a coating layer, which includes at least one coating material selected from the metal oxide, lithium-containing conductor, and conductive polymer. In this case, by coating the outer surface of the metal oxide with these coating materials to form a coating layer, the stability of the cathode material can be further improved and the volume deformation of the cathode material can be reduced.

[0066] In some embodiments, metal oxide coating materials include, for example, alumina; lithium-containing conductor coating materials include, for example, lithium niobate; and conductive polymer coating materials include, for example, polypyrrole. These coating materials can all reduce the strain of the cathode material to a certain extent.

[0067] In some embodiments, the thickness of the outer coating layer of the metal oxide is preferably 1 nm to 10 nm. At this thickness, the structural stability of the metal oxide cathode material can be improved without excessively reducing the capacity of the cathode material.

[0068] In some possible implementations, the positive electrode includes a positive current collector having two opposing surfaces, on which a positive active material layer is stacked, the positive active material layer including the positive electrode material described in the above embodiments.

[0069] In some embodiments, the mass content of the positive electrode material contained in the positive electrode active material layer of the positive electrode can be 90% to 98%, optionally 92% to 96%. In exemplary examples, it can be typical but non-limiting contents such as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, and 98%, or any range between two contents. Positive electrode materials within this content range can effectively improve the energy density of the positive electrode.

[0070] In some possible embodiments, the positive electrode active material layer may further include a conductive agent and a binder. The binder enhances the mechanical properties between the positive electrode active material layer itself and the current collector. The conductive agent effectively improves the conductivity of the positive electrode. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin. It may also include at least one of black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0071] In some possible implementations, the positive electrode active material layer may further include an electrolyte. In some embodiments, the electrolyte in the positive electrode active material layer may be at least one of the following: a sulfide Li6PS5Cl, or a binary compound such as Li2S-GeS2, Li2S-SiS2, or Li2S-P2S5, or a ternary compound such as Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.).

[0072] In some possible implementations, the positive electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, the metal foil can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, or foamed carbon, etc. The composite current collector can include a polymeric material base layer and a metal layer. The composite current collector can be formed by forming metallic materials such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys on a polymeric material substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene.

[0073] In some embodiments, the negative electrode includes a negative electrode current collector and a layer of negative electrode active material disposed on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0074] In some embodiments, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, the metal foil can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. In an exemplary embodiment, the composite current collector can include a composite material of a polymer and a metal, wherein the polymer can include, but is not limited to, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc., and the metal can include, but is not limited to, elemental lithium (or elemental sodium), lithium alloy (or sodium alloy), copper, copper alloy, iron, iron alloy, tin, tin alloy, titanium, titanium alloy, silver, silver alloy. The composite current collector can be obtained by mixing polymer and metal, or the metal can be bonded to at least one side of the polymer matrix by electroplating, coating, or other methods.

[0075] In some possible implementations, the positive current collector can be made of aluminum foil, and the negative current collector can be made of copper foil.

[0076] In some embodiments, the negative electrode active material layer contains a negative electrode active material. As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells 10. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0077] In some embodiments, the mass content of the negative electrode active material in the negative electrode active material layer may be, but is not limited to, 85% to 98%, and may be selected as 95% to 98%. In exemplary examples, it may be a typical but non-limiting content such as 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any range between two content values.

[0078] In some embodiments, the negative electrode active material layer of the negative electrode may optionally include a binder. Exemplarily, the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0079] In some embodiments, the negative electrode active material layer of the negative electrode may optionally include a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0080] In some embodiments, the negative electrode active material layer of the negative electrode may optionally include other additives, such as dispersants, thickeners (e.g., sodium carboxymethyl cellulose), etc.

[0081] In this embodiment, the battery cell 10 can be a secondary battery cell 10. A secondary battery refers to a battery cell 10 that can be recharged after discharge to activate the active materials and continue to be used. The battery cell 10 can be a lithium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a lithium-sulfur battery, etc., and this embodiment is not limited to this.

[0082] In this embodiment, the battery cell 10 may include a battery casing and electrode assemblies encapsulated within the battery casing. The shape of the battery cell 10 is not particularly limited; it may be cylindrical, square, or any other arbitrary shape. Figure 1 The shown is a square-structured battery cell 10.

[0083] In some possible implementations, such as Figure 2 As shown, the outer packaging of the battery cell 10 may include a housing 11 and a top cover assembly 12. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the top cover assembly 12 is used to cover the opening to close the receiving cavity. In this embodiment, the positive electrode sheet, separator, and negative electrode sheet contained in the battery cell 10 may be formed into an electrode assembly 13 by a winding process. The electrode assembly 13 is encapsulated in the receiving cavity. Electrolyte is immersed in the electrode assembly 13. The number of electrode assemblies 13 contained in the battery cell 10 may be one or more, which can be adjusted according to actual needs.

[0084] In this embodiment, the battery cell 10 can be a battery cell containing an electrolyte or a battery cell containing a solid electrolyte. It can also be a lithium-ion battery cell or a sodium-ion battery cell.

[0085] In some embodiments, the battery cell 10 may include a wound electrode assembly, specifically including a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode. The positive electrode, separator, and negative electrode are stacked and wound to form the electrode assembly. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrode. The electrolyte acts as a conductor of ions between the positive and negative electrode. The separator, disposed between the positive and negative electrode, primarily serves to reduce short circuits between the positive and negative electrodes, while allowing active ions such as lithium ions to pass through.

[0086] In some possible implementations, the separator can be a single component located between the positive and negative electrode plates, or it can be attached to the surface of the positive / negative electrode plates. The separator includes a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous structure separator membrane with good chemical and mechanical stability can be selected. As an example, the main material of the separator membrane can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0087] In some possible implementations, the electrolyte in the battery cell 10 acts as a conductor of ions between the positive and negative electrodes.

[0088] In some possible implementations, the battery cell 10 is a solid-state battery. In solid-state batteries, if the electrode undergoes volume deformation during charging and discharging, it is prone to losing contact with the solid electrolyte, hindering ion / electron transport, increasing interfacial impedance, and causing battery performance degradation. In the embodiments of this application, the metal oxide cathode material is simultaneously doped with multiple elements, providing high elemental bonding strength both between and within the layers of the cathode material. Furthermore, a sufficiently high concentration of doped elements can fundamentally alter the evolution characteristics of the electron cloud in the delithiation process of the cathode material, stabilizing the crystal structure of the cathode material, thereby achieving low strain in the cathode material. Applying this to solid-state batteries can effectively solve the mechanical contact problem between the cathode and the solid electrolyte.

[0089] In some possible implementations, when the battery cell 10 contains a solid electrolyte, the electrode assembly included in the battery cell 10 typically includes a positive electrode, a negative electrode, and a solid electrolyte. The positive and negative electrodes are alternately stacked, and the solid electrolyte is stacked between the positive and negative electrodes to provide insulation, separating the positive and negative electrodes. The electrode assembly containing the solid electrolyte is placed in an outer package and then encapsulated to obtain the battery cell 10.

[0090] In some possible implementations, the solid-state battery includes at least one of a sulfide all-solid-state battery, a halide all-solid-state battery, an oxide all-solid-state battery, and a polymer all-solid-state battery. In this case, the solid electrolyte may include at least one of a polymer solid electrolyte, an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

[0091] In some embodiments, the sulfide solid electrolyte includes at least one of the following: Li6PS5Cl, or binary compounds such as Li2S-GeS2, Li2S-SiS2, Li2S-P2S5, or ternary compounds such as Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.).

[0092] In some embodiments, the polymer solid electrolyte mainly consists of a high molecular weight polymer, a lithium salt, and inorganic fillers. The polymer matrix materials include polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and polyvinylidene fluoride (PVDF). These polymers form an ionicly conductive polymer electrolyte through complexation with lithium salts. Lithium salts include lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium difluorosulfonylimide (LiFSI). The solubility and degree of dissociation of these lithium salts in the polymer have a significant impact on the ionic conductivity of the electrolyte. The addition of inorganic fillers can improve the mechanical strength and ionic conductivity of the polymer electrolyte. Common inorganic fillers include active fillers and inert fillers. Active fillers, such as sulfides, phosphates, and garnet-type oxides, can themselves function as solid electrolytes. Inert fillers are mainly lithium-free inorganic materials, such as silicon dioxide, aluminum oxide, titanium dioxide, and zirconium dioxide.

[0093] In some embodiments, oxide solid electrolytes are compounds containing lithium, oxygen, and other components (such as phosphorus, titanium, aluminum, lanthanum, germanium, zinc, zirconium, etc.), and can be divided into crystalline electrolytes and amorphous electrolytes. Among them, the mainstream crystalline electrolyte material systems include garnet (LLZO) structure solid electrolytes, perovskite (LLTO) structure solid electrolytes, NASICON sodium superionic conductor solid electrolytes, and LISICON type solid electrolytes. These electrolytes exhibit high ionic conductivity and chemical stability. Amorphous electrolytes, mainly lithium phosphorus oxynitride (LiPON) type, can be used in thin-film batteries.

[0094] In some embodiments, halide solid electrolytes are mainly composed of metal halides, and their structure depends on the ionic radius and ionic arrangement. Common halide electrolytes generally fall into three categories: LiaMX4, LiaMX6, and LiaMX8, where M represents a metal element and X represents a halogen element.

[0095] In some embodiments, the battery cell 10 is a liquid battery, in which case the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent. The electrolyte salt can be selected from lithium salts, and there are no particular restrictions on the specific type; it can be selected according to actual needs. For example, the lithium salt can be selected from one or more of LiPF6, LiClO4, LiBF4, LiClF4, LiAsF6, LiSbF6, LiAlO2, LiAlCl4, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiCl, and LiI.

[0096] In some embodiments, the type of organic solvent in the electrolyte is not particularly limited and can be selected according to actual needs. Specifically, the organic solvent may also include one or more of other types of chain carbonates, cyclic carbonates, and carboxylic acid esters. The types of chain carbonates, cyclic carbonates, and carboxylic acid esters are not specifically limited and can be selected according to actual needs. The organic solvent may also include one or more of diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propionate, ethylene carbonate, propylene carbonate, butenyl carbonate, γ-butyrolactone, methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl propionate, and tetrahydrofuran.

[0097] In other embodiments, the electrolyte may also use additives. Specifically, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0098] Preparation method of battery cell 10

[0099] Secondly, embodiments of this application provide a method for preparing a battery cell 10, comprising the following steps:

[0100] S10. Preparation of chemical formula LiA x M y D Z O2 is a metal oxide cathode material, wherein A is a transition metal element, and M and D are dopant elements. The dopant element represented by M includes at least one of Mg, Al, and B; the dopant element represented by D includes at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

[0101] S20. Prepare a positive electrode including a positive electrode material;

[0102] S30. Assemble the positive electrode, negative electrode, and electrolyte to obtain a single battery cell 10.

[0103] This application describes a method for preparing a negative electrode material with the general chemical formula LiA. x M y D Z After preparing the O2 metal oxide cathode material, a cathode containing this material is fabricated and assembled with a negative electrode and electrolyte to form a battery cell 10. The fabrication process is simple and suitable for large-scale industrial production and application. In this metal oxide cathode material, low-valence elements such as Mg, Al, and B can be doped into lithium sites, providing interlayer support and improving the stability between layers in the metal oxide. High-valence metal elements such as Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W can be doped into transition metal sites, strengthening the bond with oxygen and limiting the deformation of the electron cloud around oxygen, thus improving the stability within the metal oxide layers. Furthermore, multi-element synergistic doping regulates the structural order of the cathode material, creating a voltage slope in the low-voltage region, thereby achieving a relatively considerable capacity at higher doping concentrations and increasing the cathode material's capacity. Therefore, by preparing a multi-element doped metal oxide cathode material, the electrochemical performance of the battery cell 10, including energy density, cycle life, and safety, is improved.

[0104] In step S10 above:

[0105] In some possible implementations, the methods for preparing metal oxides include solid-state sintering or co-precipitation. Solid-state sintering is a method that uses high-temperature treatment to induce diffusion and bonding between metal oxide powder particles, ultimately forming a metal oxide cathode material. For example, raw material powders are uniformly mixed and placed in a high-temperature furnace for sintering under appropriate temperature and atmosphere, causing diffusion and bonding between powder particles to form a metal oxide cathode material. Co-precipitation is a method that generates metal hydroxide or carbonate precipitates through a chemical reaction, followed by calcination to obtain the metal oxide cathode material. For example, a raw material salt is dissolved in a suitable solvent to form a metal ion solution. An appropriate precipitant (such as ammonia, sodium hydroxide, etc.) is added to the metal ion solution, causing the metal ions to react with the precipitant to generate metal hydroxide or carbonate precipitates. The generated precipitate is then filtered and washed to remove impurity ions adhering to the precipitate surface. The washed precipitate is dried and then calcined at an appropriate temperature to convert the precipitate into a metal oxide.

[0106] In some possible implementations, the solid-state sintering method includes the following steps: mixing a transition metal hydroxide precursor with a lithium source and a dopant, followed by sintering in an oxygen-containing atmosphere to obtain a metal oxide. Here, the transition metal refers to the transition metal element represented at the A-site in the metal oxide. The dopant refers to a raw material containing dopant elements represented at the M and D sites in the metal oxide. Obtaining the transition metal hydroxide precursor, mixing it with a lithium source and a dopant, and then sintering it in an oxygen-containing atmosphere allows diffusion and bonding between the raw materials to form a metal oxide cathode material.

[0107] In some embodiments, the dopant containing the dopant element may be at least one or more of oxides, acetates, and oxalates.

[0108] In some possible implementations, the solid-state sintering conditions include: sintering for 10 to 28 hours in an air atmosphere at a temperature of 650°C to 950°C, with a gas flow rate of 1 L / min to 3 L / min, followed by cooling and grinding to obtain a multi-component doped metal oxide cathode material. In this case, the solid-state sintering conditions sufficiently ensure the diffusion and bonding between the various raw material components. Exemplarily, the solid-state sintering temperature can be any typical but non-limiting point value or a range between any two points, such as 650°C, 680°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 850°C, 900°C, or 950°C. The gas flow rate can be any typical but non-limiting point value or a range between any two points, such as 1 L / min, 2 L / min, or 3 L / min. The sintering time can be any typical but non-restrictive point value or an interval between any two point values, such as 10h, 12h, 15h, 18h, 20h, 24h.

[0109] In some possible implementations, the co-precipitation method includes the following steps: preparing a mixed solution containing transition metal ions and dopant ions, adding an alkaline solution and a complexing agent to co-precipitate and obtain a doped hydroxide precursor; calcining the doped hydroxide precursor with a lithium source in an oxygen-containing atmosphere to obtain a metal oxide. Here, the transition metal ion refers to the ion of the transition metal element represented at the A-site in the metal oxide, and the dopant ion refers to the ion of the dopant element represented at the M and D sites in the metal oxide. The alkaline solution includes sodium hydroxide, potassium hydroxide, etc., and the complexing agent includes ammonia, etc. The mixed solution can be prepared by dissolving the salt of the transition metal and the salt of the dopant element in a solvent to form a mixed solution. Then, adding an alkaline solution and a complexing agent to co-precipitate the transition metal ions and dopant ions to form a hydroxide precursor of the transition metal and dopant element, followed by calcination with a lithium source to obtain a metal oxide cathode material.

[0110] In some embodiments, an aqueous solution of a water-soluble salt such as sulfate or oxalate containing the desired transition metal element is prepared, along with an aqueous solution of NaOH and an aqueous solution of a certain concentration. This solution is then added to a stirred reactor via a peristaltic pump at a controlled flow rate. Under an argon atmosphere, the pH and temperature of the solution are controlled. After a period of time, the reaction product is collected, filtered, and washed to obtain an element-doped hydroxide precursor. Further calcination with lithium salts yields multi-element-doped metal oxide cathode materials.

[0111] In some possible implementations, the transition metal element A includes at least one of Ni, Co, and Mn. In this case, the metal oxide can be a multi-layered multi-doped multi-metal oxide with a multi-component doped structure, such as multi-component doped lithium nickel oxide, multi-component doped lithium cobalt oxide, multi-component doped lithium nickel cobalt manganese oxide, multi-component doped lithium nickel cobalt oxide, or multi-component doped lithium nickel manganese oxide. Alternatively, in addition to including at least one of Ni, Co, and Mn, the transition metal element may also include Al. In this case, the metal oxide can be a multi-component doped lithium nickel cobalt aluminum oxide or a multi-component doped lithium nickel manganese aluminum oxide. Multiple doping elements simultaneously provide high bonding strength supporting elements between layers (lithium sites) and within layers (transition metal sites) of the layered cathode material, improving the structure and electrochemical performance of the metal oxide cathode material, including cycle stability and capacity.

[0112] In some possible implementations, the metal oxide has a doping concentration of 0.85 ≤ x ≤ 0.97, 0.005 ≤ y ≤ 0.05, and 0.02 ≤ z ≤ 0.1. This doping concentration improves the capacity and cycle stability of the cathode material without affecting the intrinsic electrochemical performance of the transition metal oxide.

[0113] In some possible implementations, the total molar amount of transition metal elements in the metal oxide is 100%, wherein the molar percentage of nickel is not less than 60%. In this case, the metal oxide is a high-nickel cathode material with high capacity, which can improve the energy density of the battery cell 10.

[0114] In some embodiments, in the metal oxide, the doping elements represented by M and D include Mg, Ti, Nb, and Mo, and the transition metal element represented by A includes nickel, cobalt, and manganese. Exemplarily, the preparation steps of the metal oxide cathode material include: using a precursor Ni... 0.9 Co 0.05 Mn 0.05 After uniformly mixing (OH)2, MgO, TiO2, Nb2O5, and MoO3 in a certain proportion, the mixture is placed in an oxygen atmosphere tube furnace and sintered at 700℃~800℃ for 10h~24h. The gas flow rate can be 1L / min~3L / min. After naturally cooling to room temperature, the mixture is ground to obtain a multi-element doped metal oxide cathode material.

[0115] In step S20 above:

[0116] In some possible implementations, the preparation steps of the positive electrode include: preparing a slurry containing the above-mentioned metal oxide positive electrode material positive electrode layer, coating the slurry of the positive electrode active material layer onto the surface of the positive electrode current collector, and then performing steps such as drying, rolling, and die cutting to obtain the positive electrode sheet.

[0117] In some possible implementations, the positive electrode active material layer may also include conductive agents, binders, electrolytes, and other substances.

[0118] In some possible implementations, the positive current collector may be a metal foil, a foamed metal, or a composite current collector.

[0119] In step S30 above:

[0120] In some possible implementations, a positive electrode, an electrolyte, and a negative electrode are stacked to form a battery cell 10. As an example, a positive electrode, an electrolyte, and a negative electrode are stacked to form an electrode assembly 13. The electrode assembly 13 is placed in an outer package and subjected to processes such as vacuum sealing, settling, formation, and shaping to obtain the battery cell 10.

[0121] In this application embodiment, the battery cell 10 refers to a battery assembly including a battery casing and a battery cell encapsulated within the battery casing. The shape of the battery cell 10 is not particularly limited; it can be cylindrical, square, or any other arbitrary shape. In the exemplary example, the battery cell 10 can be as follows: Figure 1 The solid-state battery cell 10 with a square structure is shown.

[0122] In some possible implementations, the battery cell 10 is a solid-state battery, in which case the electrolyte is a solid-state electrolyte.

[0123] In some possible implementations, solid-state batteries include at least one of sulfide all-solid-state batteries, halide all-solid-state batteries, oxide all-solid-state batteries, and polymer all-solid-state batteries.

[0124] In some embodiments, the battery cells of this application can be assembled into battery modules and / or battery packs. A battery module refers to a module assembled from the battery cells 10, meaning it can contain multiple battery cells 10, the specific number of which can be adjusted according to the application and capacity of the battery module. A battery pack refers to a module assembled from the aforementioned battery cells 10, meaning it can contain multiple battery cells 10, wherein multiple battery cells 10 can be assembled into a battery module 20. The specific number of battery cells 10 or battery modules 20 contained in a battery pack can be adjusted according to the application and capacity of the battery pack.

[0125] In some implementations, as shown in the appendix Figure 3This is a schematic diagram of a battery module 20 as an example. In the battery module 20, multiple battery cells 10 can be arranged sequentially along the length of the battery module 20. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 10 can be fixed by fasteners. Optionally, the battery module 20 may also include a housing with a receiving space in which the multiple battery cells 10 are received.

[0126] As in the embodiments, as shown in the appendix Figure 4 and attached Figure 5 This is a schematic diagram of a battery pack 30 as an example. The battery pack 30 may include a battery compartment and multiple battery modules 20 disposed within the battery compartment. The battery compartment includes an upper compartment 31 and a lower compartment 32. The upper compartment 31 covers the lower compartment 32, forming a closed space for accommodating the battery modules 20. The multiple battery modules 20 can be arranged in any manner within the battery compartment.

[0127] Thirdly, embodiments of this application provide an electrical device, including a battery cell 10 provided in the first aspect of embodiments of this application or a battery cell 10 prepared by the preparation method provided in the second aspect of embodiments of this application.

[0128] The electrical device provided in this application embodiment is based on the battery cell 10 or battery device of this application embodiment, therefore the electrical device of this application embodiment can work safely and for a long time.

[0129] In some implementations, the electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, portable devices, 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, electric vehicles, electric toys, power tools, etc.), electric trains, ships, satellites and spacecraft, energy storage systems, etc. The electrical device may be configured with individual battery cells 10, battery modules, or battery packs depending on its usage requirements.

[0130] As attached Figure 6 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0131] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use rechargeable batteries as their power source.

[0132] Example

[0133] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0134] Example 1

[0135] A doped ternary cathode material, the preparation of which includes the following steps:

[0136] Ni precursor 0.9 Co 0.05 Mn 0.05 After uniformly mixing (OH)2, MgO, TiO2, Nb2O5, and MoO3 in a certain proportion, the mixture was placed in an oxygen atmosphere tube furnace and sintered at 740℃ for 12 hours with a gas flow rate of 1L / min. After naturally cooling to room temperature, the mixture was ground to obtain a quaternary doped ternary cathode material, labeled as LiNi. 0.846 Co 0.047 Mn 0.047 Mg 0.02 Ti 0.02 Nb 0.01 Mo 0.01 O2.

[0137] A solid-state battery cell, the preparation of which includes the following steps:

[0138] 1. Cathode Preparation Process: The prepared quaternary doped ternary cathode material was uniformly mixed with VGCF (vapor distribution carbon fiber reinforcement) and sulfide electrolyte Li6PS5Cl at a mass ratio of 70:27:3 for 15 min to obtain a composite cathode material. The mass of the composite cathode material added to the battery was approximately 3 mAh / cm³ based on the areal capacity. 2 Confirmed. The composite cathode material is made into a slurry and coated onto the surface of the aluminum foil cathode current collector. Then, it undergoes drying, rolling, die-cutting, and other steps to obtain the cathode.

[0139] 2. Preparation of the negative electrode: Lithium-indium alloy is used as the negative electrode.

[0140] 3. Electrolyte: Li 5.5 PS5Cl 1.5 As a solid electrolyte layer, its mass is 100 mg.

[0141] 4. The positive electrode, electrolyte, and negative electrode prepared above are cold-pressed and assembled into a mold battery to obtain a solid-state battery cell.

[0142] Examples 2-16

[0143] Examples 2-23 each provide a doped metal oxide cathode material, and specific information is shown in Table 1 below. The preparation methods of the cathode material and the battery cell are the same as in Example 1.

[0144] Comparative Example 1

[0145] The difference between Comparative Example 1 and Example 1 of this application is that the cathode material used is LiNi. 0.9 Co 0.05 Mn 0.05 O2.

[0146] Comparative Examples 2-6

[0147] Comparative Examples 2-6 each provide a doped metal oxide cathode material, and specific information is shown in Table 1 below. The preparation methods of the cathode material and the battery cell are as described in Example 1.

[0148] Information on the cathode materials used in the above embodiments and comparative examples is shown in Table 1 below:

[0149] Table 1

[0150]

[0151]

[0152] To verify the progressiveness of the embodiments of this application, the following performance tests were performed on the above embodiments and comparative examples:

[0153] 1. The cell parameters of the metal oxide cathode material in the solid-state battery cell prepared in the examples before and after charging were determined by X-ray diffraction (XRD) to observe the volume deformation of the metal oxide. The test results of Example 1 are attached. Figure 7 As shown, the metal oxide cathode material in the solid-state battery cell prepared in Example 1 retains its layered transition metal oxide structure after charging, without obvious impurity phases, exhibiting small crystal strain and good stability. The atomic occupancy information obtained by Rietveld refinement of the XRD pattern of the cathode material in Example 1 is shown in Table 2 below.

[0154] Table 2

[0155]

[0156] As can be seen from the test results in Table 1 above, the four doping elements Mg, Ti, Nb and Mo are distributed in both lithium sites and transition metal sites. However, Mg is mainly doped at lithium sites, while Ti, Nb and Mo are mainly doped at transition metal sites.

[0157] The metal oxide cathode materials in the solid monomers of each embodiment and comparative example were subjected to XRD tests at a charging state of 4.3V to obtain the volume deformation rate. The specific test method was as follows: the XRD spectra of the original state and the 4.3V charging state cathode were refined by Rietveld to obtain the cell parameters, and the cell volume changes of the two were compared.

[0158] The test results are shown in Table 3 below:

[0159] Table 3

[0160] Doping elements Doping content at% Volumetric deformation % Example 1 Mg / Ti / Nb / Mo 2 / 2 / 1 / 1 1.9 Example 2 Al / Ti / Nb / Mo 2 / 2 / 1 / 1 2.8 Example 3 B / Ti / Nb / Mo 2 / 2 / 1 / 1 3.0 Example 4 Mg / Zr / Nb / Mo 2 / 2 / 1 / 1 2.2 Example 5 Mg / Ti / Nb / W 2 / 2 / 1 / 1 2.0 Example 6 Mg / La / Nb / Mo 2 / 2 / 1 / 1 2.3 Example 7 Mg / Ti / Nb / Mo 1 / 2 / 1 / 1 2.5 Example 8 Mg / Ti / Nb / Mo 1 / 1 / 1 / 1 2.1 Example 9 Mg / Ti / Nb / Mo 2 / 0.5 / 0.5 / 1 2.6 Example 10 Mg / Ti / Nb / Mo 2 / 1 / 1 / 1 2.0 Example 11 Mg / La / Ti / Nb / Mo 2 / 1 / 1 / 1 / 1 1.8 Example 12 Mg / B / Nb / Mo 1 / 1 / 2 / 2 2.7 Example 13 Mg / Al / B / Nb 1 / 0.5 / 0.5 / 2 3.2 Example 14 Mg / Ti / Nb / Mo 2 / 2 / 1 / 1 3.9 Example 15 Mg / Ti / Nb / Mo 2 / 2 / 1 / 1 3.1 Example 16 Mg / Ti / Nb / Mo 2 / 2 / 1 / 1 2.8 Comparative Example 1 / 0 6.0 Comparative Example 2 Mg 2 4.2 Comparative Example 3 Ti 2 4.6 Comparative Example 4 Nb 1 3.9 Comparative Example 5 Mo 1 4.0 Comparative Example 6 Ti / Nb / Mo 2 / 1 / 1 3.3

[0161] As can be seen from the above test results, after the metal oxide is doped with specific elements in the embodiments of this application, the volume change rate of the cathode material after charging is significantly reduced.

[0162] 2. The morphology of the metal oxide cathode material prepared in Example 1 was observed using scanning electron microscopy (SEM). The test results are attached. Figure 8 As shown, the metal oxide cathode material prepared in Example 1 has finer particles and higher uniformity.

[0163] 3. The all-solid-state batteries prepared in the above examples and comparative examples were activated at 0.1C for 3 cycles, and then subjected to 0.33C charge-discharge cycles to test their cycle stability.

[0164] The test results of Example 1 are attached. Figure 9 First charge / discharge curve and attached Figure 10 As shown in the cycle stability curves, the solid-state battery cell prepared in Example 1 exhibits a small slope in its first discharge cycle below 3.0V. It also demonstrates better cycle stability and higher capacity.

[0165] The capacity and cycle performance of the battery cells provided in each embodiment and comparative example were tested respectively:

[0166] The capacity test conditions are: room temperature, voltage range of 2.6V-4.3V, 0.1C charge and discharge, nominal specific capacity of 200mAh / g;

[0167] The test conditions for cycle performance were: room temperature, voltage range of 2.6V-4.3V, 0.33C constant current charge-discharge cycle for 35 cycles, and capacity retention rate.

[0168] The test results are shown in Table 4 below:

[0169] Table 4

[0170]

[0171]

[0172] As can be seen from the above test results, the embodiments of this application can suppress the deformation caused by volume expansion and contraction of metal oxide cathode materials during lithium insertion and extraction by using specific doping elements, reduce the total volume deformation of cathode materials, and significantly improve the cycle stability of materials without significant capacity loss.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising a positive electrode and a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, characterized in that, In the positive electrode, the positive electrode material includes materials with the general chemical formula LiA. x M y D Z O2 metal oxide, wherein A is a transition metal element, and M and D are dopant elements, wherein the dopant element represented by M includes at least one of Mg, Al, and B; and the dopant element represented by D includes at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, wherein 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

2. The battery cell as described in claim 1, characterized in that, The transition metal element shown in A includes at least one of Ni, Co, and Mn; And / or, the metal oxide has a layered structure.

3. The battery cell as described in claim 1 or 2, characterized in that, In the metal oxide, 0.85≤x≤0.97, 0.03≤y+z≤0.

15.

4. The battery cell as described in claim 3, characterized in that, In the metal oxide, 0.85≤x≤0.97, 0.005≤y≤0.05, and 0.02≤z≤0.

1.

5. The battery cell according to any one of claims 1 to 4, characterized in that, With the total molar amount of transition metal elements in the metal oxide being 100%, the molar percentage of nickel is not less than 60%.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The outer surface of the metal oxide also has a coating layer, which includes at least one coating material selected from metal oxide, lithium-containing conductor, and conductive polymer. And / or, the battery cell is a solid-state battery.

7. A method for preparing a single battery cell, characterized in that, Includes the following steps: Preparation of chemical formula LiA x M y D Z O2 is a metal oxide cathode material, wherein A is a transition metal element, and M and D are dopant elements. The dopant element represented by M includes at least one of Mg, Al, and B; the dopant element represented by D includes at least one of Fe, Ga, La, Ce, Ti, Zr, Ge, Nb, Ta, Sb, Te, Mo, and W, where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1. Prepare a positive electrode comprising the aforementioned positive electrode material; The positive electrode, negative electrode, and electrolyte are assembled to obtain a battery cell.

8. The method for preparing a single battery cell as described in claim 7, characterized in that, The methods for preparing the metal oxide include solid-state sintering or co-precipitation.

9. The method for preparing a battery cell as described in claim 8, characterized in that, The solid-state sintering method includes the following steps: mixing a transition metal hydroxide precursor with a lithium source and a dopant, and then sintering it in an oxygen-containing atmosphere to obtain the metal oxide. And / or, the steps of the coprecipitation method include: preparing a mixed solution containing transition metal ions and dopant ions, adding an alkaline solution and a complexing agent to coprecipitate, thereby obtaining a doped hydroxide precursor; and calcining the doped hydroxide precursor with a lithium source in an oxygen-containing atmosphere to obtain the metal oxide.

10. An electrical device, characterized in that, This includes battery cells as described in any one of claims 1 to 6 or battery cells prepared by the methods described in claims 7 to 9.

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