Positive electrode pieces, electrochemical apparatus and electronic apparatus

Abstract

To provide a positive pole piece which reduces the interface impedance.SOLUTION: A positive pole piece according to the present invention comprises a positive current collector and a positive material layer arranged on at least one surface of the positive current collector, the positive material layer comprises one-dimensional conductive ion fibers and a positive active material, the diameter of the one-dimensional conductive ion fiber is 0.1-10 μm, the aspect ratio is equal to or greater than 1.5, and the mass ratio of the one-dimensional conductive ion fiber to the positive electrode active material is 0.01:1-0.2:1. By regulating and controlling the diameter and the aspect ratio of the one-dimensional conductive ion fiber and the mass ratio of the one-dimensional conductive ion fiber to the positive electrode active material to be within the range, the interface impedance between the positive pole piece and the solid electrolyte and the internal impedance of the positive pole piece can be reduced, so that the electrochemical performance of the electrochemical device is improved, for example, the cycle performance is improved and the impedance is reduced.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to the field of electrochemistry technology, and particularly to a positive electrode sheet, an electrochemical device, and an electronic device.

Background Art

[0002] Lithium-ion batteries have advantages such as high energy density, high operating voltage, low self-discharge rate, small volume, and light weight, and are widely applied in the consumer electronics field. Currently, with the rapid development of electric vehicles and mobile electronic devices, the requirements for the energy density, safety characteristics, etc. of lithium-ion batteries are increasing.

[0003] With the increase in the energy density of lithium-ion batteries, the safety of lithium-ion batteries has become an urgent problem to be solved. Conventional electrolytes are generally solutions containing lithium salts and organic solvents, which have a narrow electrochemical window, a narrow applicable temperature range, generate a large amount of irreversible capacity due to the formation of a solid electrolyte interface film (SEI film), and the organic solvents have characteristics such as low boiling point and easy leakage, which can corrode the packaging bag or sealing material and may also cause potential risks. Replacing some of the liquid electrolytes in lithium-ion batteries with solid electrolytes can effectively improve the potential risks caused by the electrolytes. Solid electrolytes have characteristics such as a wide electrochemical window, a wide applicable temperature, and being difficult to burn compared to the liquid electrolyte itself, and can compensate for the defects of the liquid electrolyte in terms of safety. However, the solid electrolyte itself has no fluidity, the contact at the interface between the positive electrode sheet and the solid electrolyte is poor, and the transport of lithium ions is inhibited. Therefore, a lithium-ion battery containing a solid electrolyte, that is, a solid lithium-ion battery, solves the safety problem but has a large interfacial impedance, which affects the electrochemical characteristics of the lithium-ion battery.

Summary of the Invention

Means for Solving the Problems

[0004] The objective of embodiments of the present invention is to provide a positive electrode sheet, an electrochemical device, and an electronic device that reduce interface impedance and further improve the electrochemical characteristics of the electrochemical device.

[0005] In the content of the present invention, the present invention will be described by taking a lithium-ion battery as an example of the electrochemical device, but the electrochemical device of the present invention is not limited to the lithium-ion battery. The specific technical solutions are as follows.

[0006] In a first aspect of the present invention, a positive electrode sheet is provided, which includes a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector. The positive electrode material layer includes one-dimensional ion-conductive fibers and a positive electrode active material. The one-dimensional ion-conductive fibers have a diameter of 0.1 μm to 10 μm and an aspect ratio of 1.5 or more than 1.5. Preferably, the one-dimensional ion-conductive fibers have a diameter of 0.1 μm to 2 μm and an aspect ratio of 1.5 to 20,000. More preferably, the one-dimensional ion-conductive fibers have a diameter of 0.1 μm to 2 μm and an aspect ratio of 5 to 200. The ratio of the mass of the one-dimensional ion-conductive fibers to the mass of the positive electrode active material is 0.01:1 to 0.2:1. Preferably, the ratio of the mass of the one-dimensional ion-conductive fibers to the mass of the positive electrode active material is 0.01:1 to 0.05:1. By adjusting the diameter and aspect ratio of the one-dimensional ion-conductive fibers and the ratio of the mass of the one-dimensional ion-conductive fibers to the mass of the positive electrode active material within the above ranges, the interface impedance between the positive electrode sheet and the solid electrolyte and the internal impedance of the positive electrode sheet can be reduced. Therefore, the electrochemical characteristics of the electrochemical device are improved, and the energy density of the electrochemical device is hardly affected.

[0007] In some embodiments of the present invention, the length of the one-dimensional ion-conducting fiber is 1 μm or greater than 1 μm, preferably 1 μm to 1000 μm, and more preferably 1 μm to 100 μm. By setting the length of the one-dimensional ion-conducting fiber within the above range, there are a relatively large number of contact points between the positive electrode piece and the solid electrolyte, improving the contactability at the interface between the positive electrode piece and the solid electrolyte, further improving the continuity of lithium ion transport during charging and discharging of the electrochemical apparatus, reducing the interfacial impedance of the positive electrode piece, forming a continuous lithium ion transport passage inside the positive electrode piece, smoothly transporting lithium ions, improving the continuity of lithium ion transport inside the positive electrode piece, and reducing the internal impedance of the positive electrode piece. Thus, the electrochemical properties of the electrochemical apparatus are improved.

[0008] In some embodiments of the present invention, the mass content of the one-dimensional ion-conducting fibers is 1% to 15% of the mass of the positive electrode material layer. By controlling the mass content of the one-dimensional ion-conducting fibers within the above range, it is advantageous to improve the contactability at the interface between the positive electrode piece and the solid electrolyte, further improve the continuity of lithium ion transport during charging and discharging of the electrochemical apparatus, reduce the interfacial impedance of the positive electrode piece, form a continuous lithium ion transport passage inside the positive electrode piece, improve the continuity of lithium ion transport inside the positive electrode piece, and reduce the internal impedance of the positive electrode piece. Thus, the electrochemical properties of the electrochemical apparatus are improved.

[0009] In some embodiments of the present invention, the ionic conductivity of the one-dimensional ion-conducting fiber is 1 × 10⁻¹⁶ -6 It is S / cm, or 1 × 10 -6The conductivity is greater than S / cm. The fact that the ionic conductivity of the one-dimensional ion-conducting fiber is within the above range indicates that the one-dimensional ion-conducting fiber has good ionic conductivity characteristics. Therefore, lithium ions can be smoothly transported at the interface between the positive electrode and the solid electrolyte, reducing the interfacial impedance of the positive electrode, ensuring continuity of lithium ion transport within the positive electrode, and reducing the internal impedance of the positive electrode. Thus, the electrochemical properties of the electrochemical apparatus are improved.

[0010] In some embodiments of the present invention, the positive electrode piece satisfies at least one of the following (1) and (2): (1) The one-dimensional ion-conducting fiber comprises cellulose modified with copper ions. (2) The one-dimensional ion-conducting fiber comprises a polymer fiber comprising an ion-conducting material and a polymer, wherein the ion-conducting material comprises at least one of LATP, LLZO, LLTO, LLZTO, LAGP and doped compounds of these compounds, the doping element of the doped compound comprises at least one of Al, Ge, and Si, the polymer comprises at least one of polyacrylonitrile, polyaniline, polyfluoroethylene, polymethyl methacrylate, and polyacrylic acid, and the ratio of the mass of the ion-conducting material to the mass of the polymer is 1:2 to 1:1. By selecting the above-mentioned type of one-dimensional ion-conducting fiber, it is possible to improve the contactability at the interface between the positive electrode piece and the solid electrolyte. Furthermore, it is advantageous to improve the continuity of lithium ion transport during charging and discharging of the electrochemical apparatus, reduce the interfacial impedance of the positive electrode piece, form a continuous lithium ion transport passage inside the positive electrode piece, improve the continuity of lithium ion transport inside the positive electrode piece, and reduce the internal impedance of the positive electrode piece.

[0011] In some embodiments of the present invention, the positive electrode active material comprises at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickel cobalt manganese, and lithium-rich manganese material. Selecting one of the above types of positive electrode active materials is advantageous in obtaining an electrochemical apparatus with good cycle characteristics.

[0012] In some embodiments of the present invention, the thickness of the positive electrode material layer is 3 μm to 195 μm, and the thickness of the positive electrode piece is 15 μm to 200 μm. Controlling the thickness of the positive electrode material layer and the positive electrode piece within the above range is advantageous in obtaining an electrochemical apparatus with good cycle characteristics.

[0013] In a second aspect of the present invention, an electrochemical apparatus is provided comprising a solid electrolyte and a positive electrode piece described in any of the above embodiments. The electrochemical apparatus provided by the present invention has good electrochemical properties.

[0014] In a third aspect of the present invention, an electronic apparatus is provided that includes an electrochemical apparatus as described in any of the above embodiments. The electronic apparatus provided by the present invention has good operating characteristics. [Effects of the Invention]

[0015] The present invention provides a positive electrode piece, an electrochemical apparatus, and an electronic apparatus. The positive electrode piece includes a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector. The positive electrode material layer includes one-dimensional ion-conducting fibers and a positive electrode active material. The one-dimensional ion-conducting fibers have a diameter of 0.1 μm to 10 μm, an aspect ratio of 1.5 or more, and a ratio of the mass of the one-dimensional ion-conducting fibers to the mass of the positive electrode active material of 0.01:1 to 0.2:1. By adjusting the diameter and aspect ratio of the one-dimensional ion-conducting fibers, as well as the ratio of the mass of the one-dimensional ion-conducting fibers to the mass of the positive electrode active material, within the above ranges, the interfacial impedance between the positive electrode piece and the solid electrolyte and the internal impedance of the positive electrode piece can be reduced. Furthermore, the electrochemical properties of the electrochemical apparatus can be improved, for example, by improving cycle characteristics and reducing impedance.

[0016] Of course, it is not necessary to achieve all of the above advantages simultaneously in order to implement any of the products or methods of the present invention. [Brief explanation of the drawing]

[0017] To more clearly illustrate the embodiments of the present invention or the technical concepts of the prior art, the drawings used in the embodiments or prior art will be briefly described below. However, it will be apparent to those skilled in the art that the drawings described below are merely some embodiments of the present invention, and other embodiments can be obtained based on these drawings. [Figure 1] Figure 1 is a schematic diagram of the positive electrode component of the correlation technology. [Figure 2] Figure 2 is a schematic diagram showing the changes in the internal structure of the positive electrode piece during charging and discharging, as shown in Figure 1. [Figure 3] Figure 3 shows the cycle characteristics measurement diagrams for Example 16 and Comparative Example 3. [Modes for carrying out the invention]

[0018] The following describes the technical solutions of embodiments of the present invention clearly and completely with reference to the drawings of the embodiments of the present invention. However, it is clear that the embodiments described are only a part of the present invention and not all embodiments. Based on the embodiments of the present invention, all other embodiments that a person skilled in the art can obtain based on the present invention are within the scope of the protection of the present invention.

[0019] In the section describing embodiments for carrying out the present invention, a lithium-ion battery is used as an example of an electrochemical apparatus; however, the electrochemical apparatus of the present invention is not limited to a lithium-ion battery. Specific technical examples are as follows.

[0020] In solid-state lithium-ion batteries, introducing an ion-conducting material such as a solid electrolyte into the positive electrode piece can improve the problem of high interfacial impedance and high internal impedance caused by the poor ion transportability of the positive electrode active material itself in the positive electrode piece. Currently, many solid electrolytes are particulate, and as shown in Figure 1, the positive electrode piece 10 includes a positive electrode current collector 11 and a positive electrode material layer 12 provided on the surface of the positive electrode current collector 11. The positive electrode material layer 12 includes a solid electrolyte 121, a positive electrode active material 122, and a binder 123. Since both the solid electrolyte 121 and the positive electrode active material 122 are particulate, there are few contact points between them. As a result, even with the introduction of the solid electrolyte 121, it is difficult to form continuous lithium ion pathways on the surface and inside the positive electrode piece 10, and the lithium ion impedance remains high. Therefore, the interfacial impedance and the internal impedance of the positive electrode piece remain high. Increasing the content of the solid electrolyte 121 to improve lithium ion transportability affects the energy density of the solid-state lithium-ion battery. Furthermore, during charging and discharging of a solid lithium-ion battery, the increase in particle volume of the positive electrode active material partially blocks the lithium ion transport path (as shown in Figure 2), thereby further increasing the interfacial impedance and the internal impedance of the positive electrode piece, affecting the electrochemical properties of the solid lithium-ion battery. In view of the above problems, the present invention provides a positive electrode piece, an electrochemical device, and an electronic device to reduce the interfacial impedance and the internal impedance of the positive electrode piece and improve the electrochemical properties of the electrochemical device. In the present invention, a solid lithium-ion battery is a total solid lithium-ion battery, a semi-solid lithium-ion battery, or a quasi-solid lithium-ion battery, of which a total solid lithium-ion battery is a lithium-ion battery that does not contain an electrolyte, a semi-solid lithium-ion battery is a lithium-ion battery in which the ratio of the mass of the electrolyte to the mass of the lithium-ion battery is 0.05 to 0.1, and a quasi-solid lithium-ion battery is a lithium-ion battery in which the ratio of the mass of the electrolyte to the mass of the lithium-ion battery is greater than 0 and less than 0.05.

[0021] In a first embodiment of the present invention, a positive electrode piece is provided, the positive electrode piece comprising a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector, the positive electrode material layer comprising one-dimensional ion-conducting fibers and a positive electrode active material, the one-dimensional ion-conducting fibers having a diameter of 0.1 μm to 10 μm and an aspect ratio of 1.5 or greater than 1.5. Preferably, the one-dimensional ion-conducting fibers have a diameter of 0.1 μm to 2 μm and an aspect ratio of 1.5 to 20000. More preferably, the one-dimensional ion-conducting fibers have a diameter of 0.1 μm to 2 μm and an aspect ratio of 5 to 200. The ratio of the mass of the one-dimensional ion-conducting fibers to the mass of the positive electrode active material is 0.01:1 to 0.2:1, preferably 0.01:1 to 0.05:1. For example, the diameter D of a one-dimensional ion-conducting fiber may be 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 1 μm, 2 μm, 5 μm, 7 μm, or 10 μm, or may be within the range of any two of these values. For example, the aspect ratio X of a one-dimensional ion-conducting fiber may be 1.5, 5, 10, 50, 100, 150, 200, 500, 1000, 2000, 3000, 5000, 10000. The ratio Y of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material may be 0.01:1, 0.02:1, 0.05:1, 0.08:1, 0.1:1, 0.12:1, 0.15:1, 0.18:1, or 0.2:1, or may be in the range of any two of these values. The meaning of "positive electrode material layer provided on at least one surface of the positive electrode current collector" above is that the positive electrode material layer may be provided on one surface along the thickness direction of the positive electrode current collector, or it may be provided on two surfaces along the thickness direction of the positive electrode current collector. The term "surface" here may refer to the entire surface area of ​​the positive electrode current collector, or to a part of the surface area of ​​the positive electrode current collector, and there are no particular limitations in the present invention as long as the objective of the present invention can be achieved.

[0022] The positive electrode piece includes a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector. The positive electrode material layer includes one-dimensional ion-conducting fibers and a positive electrode active material. On the one hand, the linear structure of the one-dimensional ion-conducting fibers provides good interfacial contact between the positive electrode piece and the solid electrolyte, improving the continuity of lithium ion transport during charging and discharging of the electrochemical device and reducing the interfacial impedance of the positive electrode piece. On the other hand, the addition of one-dimensional ion-conducting fibers creates good interfacial contact with the positive electrode active material particles in the positive electrode piece, enabling smooth lithium ion transport. Furthermore, because the one-dimensional ion-conducting fibers have a linear structure, they are less affected by volume changes of the positive electrode active material. This allows for continued good interfacial contact between the one-dimensional ion-conducting fibers and the positive electrode active material during charging and discharging of the electrochemical device, ensuring smooth lithium ion transport, improving the continuity of lithium ion transport within the positive electrode piece, and reducing the internal impedance of the positive electrode piece. As a result, the positive electrode piece provided by the present invention can be used in electrochemical apparatuses containing a solid electrolyte, reducing the interfacial impedance between the positive electrode piece and the solid electrolyte, as well as the internal impedance of the positive electrode piece. Furthermore, it can improve the electrochemical properties of the electrochemical apparatus, for example, by improving cycle characteristics and reducing impedance.

[0023] Specifically, if the diameter of the one-dimensional ion-conducting fiber is too small, for example, less than 0.1 μm, the manufacturing difficulty of the one-dimensional ion-conducting fiber increases, raising costs, and the one-dimensional ion-conducting fiber becomes more prone to breakage, affecting the continuity of lithium ion transport in the positive electrode piece. If the diameter of the one-dimensional ion-conducting fiber is too large, for example, greater than 10 μm, the interfacial contact between the positive electrode piece and the solid electrolyte is poor, increasing the interfacial impedance. If the aspect ratio of the one-dimensional ion-conducting fiber is too small, for example less than 1.5, the characteristics of its linear structure are not clear, making it difficult to improve the continuity of lithium ion transport. If the ratio of the mass of the one-dimensional ion-conducting fibers to the mass of the positive electrode active material is too small, for example, less than 0.01:1, the content of the one-dimensional ion-conducting fibers is low, making it impossible to form a continuous lithium-ion transport channel and thus failing to improve the continuity of lithium-ion transport. If the ratio of the mass of the one-dimensional ion-conducting fibers to the mass of the positive electrode active material is too large, for example, greater than 0.2:1, the content of the positive electrode active material decreases, thus affecting the energy density of the electrochemical apparatus. By adjusting the diameter and aspect ratio of the one-dimensional ion-conducting fibers, as well as the ratio of the mass of the one-dimensional ion-conducting fibers to the mass of the positive electrode active material, within the above range, the interfacial impedance between the positive electrode piece and the solid electrolyte and the internal impedance of the positive electrode piece can be reduced. Thus, the electrochemical properties of the electrochemical apparatus are improved, with little effect on the energy density of the electrochemical apparatus.

[0024] In some embodiments of the present invention, the length L of the one-dimensional ion-conducting fiber is 1 μm or greater than 1 μm, preferably 1 μm to 1000 μm, and more preferably 1 μm to 100 μm. For example, the length of the one-dimensional ion-conducting fiber may be 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 300 μm, 500 μm, 800 μm, or 1000 μm, or within a range of any two of these values. By setting the length of the one-dimensional ion-conducting fiber within the above range, it is advantageous to have a relatively large number of contact points between the positive electrode piece and the solid electrolyte, to improve contactability at the interface between the positive electrode piece and the solid electrolyte, to further improve the continuity of lithium ion transport during charging and discharging of the electrochemical apparatus, to reduce the interfacial impedance of the positive electrode piece, to form a continuous lithium ion transport passage inside the positive electrode piece, to smoothly transport lithium ions, to improve the continuity of lithium ion transport inside the positive electrode piece, and to reduce the internal impedance of the positive electrode piece. Therefore, the electrochemical properties of the electrochemical apparatus are improved.

[0025] In some embodiments of the present invention, the mass content W of the one-dimensional ion-conducting fibers is 1% to 15% of the mass of the positive electrode material layer. For example, the mass content of the one-dimensional ion-conducting fibers may be 1%, 3%, 5%, 7%, 9%, 10%, 12%, or 15%, or within a range of any two of these values. Controlling the mass content of the one-dimensional ion-conducting fibers within the above range improves the contactability at the interface between the positive electrode piece and the solid electrolyte, further improves the continuity of lithium ion transport during charging and discharging of the electrochemical apparatus, reduces the interfacial impedance of the positive electrode piece, forms a continuous lithium ion transport passage inside the positive electrode piece, improves the continuity of lithium ion transport inside the positive electrode piece, and reduces the internal impedance of the positive electrode piece. Thus, the electrochemical properties of the electrochemical apparatus are improved.

[0026] In the present invention, the content in the positive electrode material layer of the positive electrode active material can be calculated from the ratio Y of the mass of the one-dimensional ion conductive fiber to the mass of the positive electrode active material and the mass content rate W of the one-dimensional ion conductive fiber, and can be selected according to the situation. Exemplarily, the mass content rate of the positive electrode active material may be 60% to 99%, preferably 80% to 99%, based on the mass of the positive electrode material layer.

[0027] In some embodiments of the present invention, the ionic conductivity of the one-dimensional ion conductive fiber is 1×10 -6 S / cm, or more than 1×10 -6 S / cm, preferably 1×10 -6 S / cm to 1×10 2 S / cm. For example, the ionic conductivity of the one-dimensional ion conductive fiber is 1×10 -6 S / cm, 1×10 -5 S / cm, 1×10 -4 S / cm, 1×10 -3 S / cm, 1×10 -2 S / cm, 1×10 S / cm, or 1×10 2 S / cm, or may be in the range consisting of any two of these numerical values. The ionic conductivity of the one-dimensional ion conductive fiber being within the above range indicates that the one-dimensional ion conductive fiber has good ionic conductivity. Therefore, lithium ions can be smoothly transported at the interface between the positive electrode sheet and the solid electrolyte, the interfacial impedance of the positive electrode sheet can be reduced, the continuity of lithium ion transport inside the positive electrode sheet can be maintained, and the internal impedance of the positive electrode sheet can also be reduced. Therefore, the electrochemical characteristics of the electrochemical device are improved.

[0028] In some embodiments of the present invention, the one-dimensional ion conductive fiber may be a conductive one-dimensional ion conductive fiber or a non-conductive one-dimensional ion conductive fiber. When the one-dimensional ion conductive fiber is a conductive one-dimensional ion conductive fiber, the electronic conductivity of the one-dimensional ion conductive fiber is 10 -8 S / cm to 10 8The value may be S / cm. This can improve contact at the interface between the positive electrode and the solid electrolyte, reduce the interfacial impedance of the positive electrode, improve the continuity of lithium ion transport within the positive electrode, and reduce the internal impedance of the positive electrode, in addition to improving the electronic conductivity of the positive electrode and further improving the electrochemical properties of the electrochemical apparatus.

[0029] In some embodiments of the present invention, the one-dimensional ion-conducting fiber comprises copper ion-modified cellulose. In some embodiments of the present invention, the one-dimensional ion-conducting fiber comprises a polymer fiber comprising an ion-conducting material and a polymer, wherein the ion-conducting material comprises at least one of LATP, LLZO, LLTO, LLZTO, LAGP and doped compounds of these compounds, the doping element of the doped compound comprises at least one of Al, Ge, and Si, and the polymer comprises at least one of polyacrylonitrile, polyaniline, polyfluoroethylene, polymethyl methacrylate, and polyacrylic acid, and the ratio of the mass of the ion-conducting material to the mass of the polymer is 1:2 to 1:1. In some embodiments of the present invention, the one-dimensional ion-conducting fiber comprises copper ion-modified cellulose and the polymer fiber described above. By selecting the above-described type of one-dimensional ion-conducting fiber, it is possible to improve the contactability at the interface between the positive electrode piece and the solid electrolyte, further improve the continuity of lithium ion transport during charging and discharging of the electrochemical apparatus, reduce the interfacial impedance of the positive electrode piece, and also form a continuous lithium ion transport passage inside the positive electrode piece, thereby improving the continuity of lithium ion transport inside the positive electrode piece and reducing the internal impedance of the positive electrode piece. Thus, the electrochemical properties of the electrochemical apparatus are improved. The copper ion-modified cellulose is obtained by immersing cellulose in a salt solution containing copper ions, and the mass content of copper ions in the copper ion-modified cellulose may be 0.1% to 10%. The copper ion-containing salt solution may include a solution containing at least one copper salt from copper nitrate and copper sulfate, but is not limited to these. The copper ion-containing salt solution may also be an aqueous solution of copper salt or an ethanol solution. The present invention does not have any particular limitations on the immersion time and temperature, as long as the objective of the present invention is achieved. The present invention does not have any particular limitations on the mass content of the doped element in the doped compound, as long as the objective of the present invention is achieved. Exemplarily, the mass content of the doped element relative to the doped compound is 0.01% to 3%. In the present invention, LATP is lithium aluminum titanium phosphate, and its general formula is Li 1+u Alu Ti 2-u (PO4)3, where 0 ≤ u ≤ 0.5, specifically, Li 1.3 A l0.3 Ti 1.7 (PO4)3, Li 1.5 Al 0.5 Ti 1.5 (PO4)3, etc. may be used. LLZO is Li7La3Zr2O 12 , LLTO is lithium lanthanum titanate, and its general formula is Li 3v La 2 / 3-v TiO3, where 0 ≤ v ≤ 0.2, specifically, Li 0.34 La 0.55 TiO3, Li 0.5 La 0.5 TiO3, Li 0.33 La 0.56 TiO3, Li 0.35 La 0.55 TiO3, etc. may be used. LLZTO is Li 6.4 La3Zr 1.4 Ta 0.6 O 12 , and LAGP is Li 1.5 A l0.5 Ge 1.5 P3O 12 .

[0030] In some embodiments of the present invention, the cathode active material includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium-rich manganese materials. Among them, lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.5 Co 0.3 Mn 0.2The lithium-rich manganese material may contain at least one of the following: O2 (NCM532), but is not limited to these. The lithium-rich manganese material may contain at least one of the following: LiMnO, LiCoO, Li2MnO, LiNiCoO, x1LiMnO·(1-x1)LiNiMnO, and x2LiMnO·(1-x2)LiNiCoMnO, but is not limited to these, where x1 and x2 are 0≦x1≦1 and 0≦x2≦1. Selecting the above types of positive electrode active materials is advantageous in obtaining an electrochemical apparatus with good cycle characteristics.

[0031] In some embodiments of the present invention, the thickness H1 of the positive electrode material layer is 3 μm to 195 μm, and the thickness H2 of the positive electrode piece is 15 μm to 200 μm, preferably the thickness of the positive electrode material layer is 30 μm to 80 μm, and the thickness of the positive electrode piece is 35 μm to 200 μm. For example, the thickness of the positive electrode material layer may be 3 μm, 5 μm, 10 μm, 20 μm, 30 μm, 50 μm, 80 μm, 100 μm, 130 μm, 150 μm, 180 μm, or 195 μm, and for example the thickness of the positive electrode piece may be 15 μm, 20 μm, 30 μm, 35 μm, 50 μm, 80 μm, 100 μm, 130 μm, 150 μm, 180 μm, or 200 μm. Controlling the thickness of the positive electrode material layer and positive electrode piece within the above range is advantageous in obtaining an electrochemical apparatus with good cycle characteristics.

[0032] The present invention is not particularly limited to methods for producing one-dimensional ion-conducting fibers, and is sufficient as long as the objective of the present invention is achieved. For example, a method for producing one-dimensional ion-conducting fibers may include, but is not limited to, the steps of dissolving an ion-conducting substance having mass m1 and a polymer having mass m2 in an organic solvent of volume V, stirring until homogeneous to obtain a spinning solution, then obtaining fibers from the spinning solution by electrospinning, drying and setting aside, pre-oxidizing in an air furnace, and then performing heat treatment in a nitrogen gas or air atmosphere to obtain one-dimensional ion-conducting fibers. The ion-conducting material includes at least one of LATP, LLZO, LLTO, LLZTO, LAGP, and doped compounds of these compounds, the doping element of the doped compound includes at least one of Al, Ge, and Si, the polymer may include at least one of polyacrylonitrile, polyaniline, polyfluoroethylene, polymethyl methacrylate, and polyacrylic acid, but is not limited to these, the organic solvent may include at least one of N,N-dimethylformamide, acetone, and ethanol, but is not limited to these, the units of m1 and m2 are g, the unit of V is mL, the ratio of m1 to m2 is 1:2 to 1:1, the present invention does not have any particular restrictions on the mass concentration of the spinning solution, as long as the object of the present invention is achieved, for example the mass concentration of the spinning solution may be 6% to 20%, preferably 8% to 19%. The present invention does not have any particular limitations on the particle size of the ion-conducting material, and typically the particle size of the ion-conducting material is smaller than the diameter of the fiber, and exemplary, the volume-average particle size of the ion-conducting material is 100 nm to 1000 nm.What needs to be understood is that if the volume-average particle size of the ion-conducting material is smaller than the diameter of the one-dimensional ion-conducting fiber, the ion-conducting material will coat the fiber, and of course, some of the ion-conducting material may be partially embedded in the fiber and some may not be. If the volume-average particle size of the ion-conducting material is larger than the diameter of the one-dimensional ion-conducting fiber, the ion-conducting material may be partially embedded in the fiber and some may not be. Typically, if the volume-average particle size of the ion-conducting material is larger than the diameter of the one-dimensional ion-conducting fiber, the volume-average particle size of the ion-conducting material must be equal to or smaller than twice the diameter of the one-dimensional ion-conducting fiber. The present invention does not have any particular limitations on the temperature and time of the pre-oxidation and heat treatment described above, as long as the objective of the present invention is achieved. For example, the pre-oxidation temperature T1 is 180°C to 250°C, the time t1 is 0.5h to 3h, the heating rate S1 is 0.5°C / min to 3°C / min, the heat treatment temperature T2 is 500°C to 1200°C, the time t2 is 0.5h to 8h, and the heating rate S2 is 0.5°C / min to 6°C / min.

[0033] Typically, the diameter of one-dimensional ion-conducting fibers can be adjusted by controlling the spinning voltage and the mass concentration of the spinning solution in electrospinning. For example, increasing the spinning voltage reduces the diameter of the one-dimensional ion-conducting fibers, while decreasing the spinning voltage increases the diameter. Furthermore, for example, increasing the mass concentration of the spinning solution increases the diameter of the one-dimensional ion-conducting fibers, while decreasing the mass concentration of the spinning solution reduces the diameter. The aspect ratio of one-dimensional ion-conducting fibers can be obtained by grinding the fibers, yielding one-dimensional ion-conducting fibers with different aspect ratios. Typically, extending the grinding time reduces the aspect ratio of the one-dimensional ion-conducting fibers, while shortening the grinding time increases the aspect ratio. The present invention is not limited to the above-mentioned grinding method and time, and can be selected according to the situation, as long as one-dimensional ion-conducting fibers with the desired aspect ratio can be obtained.

[0034] The present invention has no particular limitations on the positive electrode current collector, as long as it can achieve the objectives of the present invention. For example, it may include aluminum foil, aluminum alloy foil, and composite current collectors (e.g., aluminum-carbon composite current collectors). The present invention also has no particular limitations on the thickness of the positive electrode current collector, as long as it can achieve the objectives of the present invention. For example, the thickness of the positive electrode current collector is 5 μm to 15 μm.

[0035] In the present invention, the positive electrode material layer may further contain a conductive agent and a binder, and the present invention is not particularly limited to the type of conductive agent and binder, as long as the object of the present invention can be achieved. For example, the conductive agent may include, but is not limited to, at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, flake graphite, Ketjenblack, graphene, metallic materials, and conductive polymers. The carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The carbon fibers may include, but are not limited to, vapor-grown carbon fibers (VGCF) and / or nanocarbon fibers. The metallic materials may include, but are not limited to, metal powders and / or metal fibers, and specifically, the metal may include, but is not limited to, at least one of copper, nickel, aluminum, and silver. The conductive polymer may include, but is not limited to, at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene, and polypyrrole. For example, the binder may contain, but is not limited to, at least one of the following: polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethylcellulose, sodium carboxymethylcellulose, lithium carboxymethylcellulose, polyimide, polyamide-imide, styrene-butadiene rubber, and polyvinylidene fluoride.

[0036] Optionally, the positive electrode piece may include a conductive layer, the conductive layer located between the positive electrode current collector and the positive electrode material layer. There are no particular restrictions on the composition of the conductive layer, and it may be a conductive layer commonly used in the art. The conductive layer includes a conductive agent and a binder. The present invention has no particular restrictions on the conductive agent and binder in the conductive layer, and for example, it may contain at least one of the above conductive agent and binder.

[0037] In a second aspect of the present invention, an electrochemical apparatus is provided comprising a solid electrolyte and a positive electrode piece as described in any of the above embodiments. Thereafter, the electrochemical apparatus provided by the present invention has good electrochemical properties. In the present invention, the electrochemical apparatus further comprises a negative electrode piece and a separator, wherein the positive electrode piece, separator, and negative electrode piece are stacked in order to obtain an electrode assembly. The separator separates the positive electrode piece and the negative electrode piece to prevent internal short circuits in the electrochemical apparatus and to allow electrolyte ions to pass freely without affecting the progress of the electrochemical charge-discharge process.

[0038] In this invention, the solid electrolyte is Li 2+x Al 2+x Si 1-x S6, Li3YCl6, Li3YBr6, Li3OCl, LiPON, Li 0.5 La 0.5 TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li7La3Zr2O 12 Li 10 GeP2S 12 (LGPS), Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 3.25 Ge 0.25 P 0.75 S4, Li 11 AlP2S 12 , and Li7P3S 11 It includes at least one of the following, where 0 ≤ x < 1.

[0039] In the present invention, the negative electrode piece comprises only the negative electrode current collector, or the negative electrode piece comprises the negative electrode current collector and a negative electrode material layer provided on at least one surface of the negative electrode current collector. The meaning of "provided on at least one surface of the negative electrode current collector" is that the negative electrode material layer may be provided on one surface along the thickness direction of the negative electrode current collector, or on two surfaces along the thickness direction of the negative electrode current collector. The term "surface" here may refer to the entire surface area of ​​the negative electrode current collector, or to a part of the surface area of ​​the negative electrode current collector, and there are no particular limitations in the present invention as long as the objective of the present invention can be achieved.

[0040] The present invention is not particularly limited in terms of the negative electrode current collector, and only needs to achieve the objectives of the present invention. For example, it may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collectors (e.g., lithium copper composite current collector, carbon copper composite current collector, nickel copper composite current collector, titanium copper composite current collector, etc.).

[0041] The negative electrode material layer contains a negative electrode active material, and the present invention is not particularly limited to the negative electrode active material, as long as it can achieve the objectives of the present invention. For example, the negative electrode active material may be natural graphite, artificial graphite, mesocarbon microbeads, hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, or lithium-ionized TiO2-Li4Ti5O with a spinel structure. 12 Alternatively, it may include, but is not limited to, at least one of the Li-Al alloys.

[0042] The negative electrode material layer further comprises a conductive agent and a binder. The present invention is not particularly limited in terms of the type of conductive agent and binder, as long as the objectives of the present invention can be achieved. For example, at least one of the above conductive agent and binder may be used. The present invention is not particularly limited in terms of the mass ratio of the negative electrode active material, conductive agent and binder in the negative electrode material layer, and those skilled in the art can select them according to their actual needs, as long as the objectives of the present invention can be achieved.

[0043] The present invention does not have any particular limitations on the thickness of the negative electrode material layer, as long as the objective of the present invention is achieved. For example, the thickness of the negative electrode material layer is 30 μm to 120 μm. The present invention does not have any particular limitations on the thickness of the negative electrode current collector, as long as the objective of the present invention is achieved. For example, the thickness of the negative electrode current collector is 5 μm to 35 μm. The present invention does not have any particular limitations on the thickness of the negative electrode piece, as long as the objective of the present invention is achieved. For example, the thickness of the negative electrode piece is 50 μm to 250 μm.

[0044] Optionally, the negative electrode piece may include a conductive layer, the conductive layer located between the negative electrode current collector and the negative electrode material layer. The present invention has no particular limitations on the composition of the conductive layer, and may include conductive layers commonly used in the art. For example, the conductive layer includes a conductive agent and a binder. The present invention has no particular limitations on the conductive agent and binder in the conductive layer, and may include, for example, at least one of the above conductive agent and binder.

[0045] The electrochemical apparatus of the present invention is not particularly limited and may include any apparatus for initiating an electrochemical reaction. In some embodiments of the present invention, the electrochemical apparatus may include, but is not limited to, a lithium-ion secondary battery (lithium-ion battery) or a lithium-ion polymer secondary battery. The present invention is not particularly limited in terms of the shape of the electrochemical apparatus, as long as it can achieve the objectives of the present invention. For example, it may include, but is not limited to, cylindrical batteries, prismatic batteries, batteries of special shapes, or button batteries.

[0046] The manufacturing process of the electrochemical apparatus according to the present invention is well known to those skilled in the art, and the present invention is not particularly limited. For example, it may include, but is not limited to, the following steps: A positive electrode piece, a separator, and a negative electrode piece are stacked in order, a solid electrolyte is added, and if necessary, the assembly is wound or folded to obtain a wound electrode assembly, and the electrode assembly is placed in a packaging bag and sealed to obtain the electrochemical apparatus. Alternatively, a positive electrode piece, a separator, and a negative electrode piece are stacked in order, a solid electrolyte is added, and the four corners of the entire stacked structure are fixed with tape to obtain a stacked electrode assembly, and the electrode assembly is placed in a packaging bag and sealed to obtain the electrochemical apparatus. Furthermore, if necessary, an overcurrent prevention element, lead plates, etc., may be placed in the packaging bag to prevent pressure rise and overcharging / discharging inside the electrochemical apparatus. The packaging bag is a packaging bag known in the art, and the present invention is not limited to it.

[0047] In a third aspect of the present invention, an electronic apparatus is provided that includes an electrochemical apparatus as described in any of the above-described embodiments. The electronic apparatus provided by the present invention has good performance.

[0048] The present invention is not particularly limited in terms of the type of electronic device, and may include any electronic device used in the prior art. In some embodiments, the electronic device may include, but is not limited to, a notebook computer, a pen-input personal computer, a mobile computer, an e-book player, a mobile phone, a portable fax machine, a portable copier, a portable printer, stereo headphones, a video recorder, an LCD television, a portable cleaner, a portable CD player, a MiniDisc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, an electric assist bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household storage battery, and a lithium-ion capacitor.

[0049] Examples Embodiments of the present invention will be described in more detail below with reference to examples and comparative examples. Various tests and evaluations will be carried out according to the following methods.

[0050] Test methods and equipment Measurement of diameter D, length L, and aspect ratio X of one-dimensional ion-conducting fibers. The manufactured one-dimensional ion-conducting fiber material was dispersed on a silicon wafer using anhydrous ethanol. Electron microscope images were taken using a scanning electron microscope (SEM (ZEISS)), and the diameter D and length L of the one-dimensional ion-conducting fibers in the electron microscope images were measured. Twenty fibers were measured, and the average value was used as the final result. The aspect ratio of the one-dimensional ion-conducting fiber is X = L / D.

[0051] Measurement of ionic conductivity One-dimensional ion-conducting fibers were compressed into a 14mm diameter disc using a tablet press at a pressure of 10 MPa. A pair of batteries were assembled using a steel slab-disc-steel slab, and the AC impedance was measured using an AC impedance meter. The ionic conductivity of the one-dimensional ion-conducting fiber was calculated as: Ionic conductivity = Disc thickness / (AC impedance × Measurement area). Three tests were performed for each example, and the average value was used as the final result. The measurement area was circular, with a diameter of 5mm, and the steel slab was made of 316 stainless steel.

[0052] Measurement of the thickness of the positive electrode material layer and positive electrode piece The thickness of the positive electrode piece and positive electrode current collector in each example and comparative example was measured with a micrometer with an accuracy of 0.0001 mm. The thickness of the positive electrode material layer = thickness of the positive electrode piece - thickness of the positive electrode current collector.

[0053] Cycle Characteristics Measurement Under conditions of 25°C, the lithium-ion battery was charged to 3.7V with a constant current of 0.5C, then charged at a constant voltage of 3.7V until the current fell below 0.025C, allowed to stand for 5 minutes, and discharged to 2.8V with a constant current of 0.5C. The above procedure constituted one charge-discharge cycle, and the discharge capacity of each cycle was recorded. The lithium-ion battery was cycled multiple times under the above conditions, and the discharge capacity of the lithium-ion battery in each cycle was measured. In the 50th, 100th, 150th, 200th, and 250th cycles, the lithium-ion battery was charged to 3.7V with a constant current of 0.05C, then charged at a constant voltage until the current fell below 0.025C at 3.7V, allowed to stand for 5 minutes, and discharged to 2.8V with a constant current of 0.05C. The initial discharge capacity was set as 100%, and the charge-discharge cycle was repeated until the discharge capacity retention rate decreased to 80% of the initial discharge capacity. At that point, the measurement was stopped, the number of cycles was recorded, and this was used as an index to evaluate the cycle characteristics of the lithium-ion battery. Capacity retention rate = (Capacity after discharge of each cycle / Initial discharge capacity) × 100%.

[0054] Impedance measurement At 25±2℃, the lithium-ion battery was charged with a constant current of 0.1C until the voltage reached 4.4V, then charged again with a constant voltage of 4.45V until the current reached 0.05C, and left to stand for 10 minutes. It was then discharged with a current of 0.1C until the voltage reached 3.4V, and left to stand for 5 minutes. It was then charged again with a constant current of 0.1C until the voltage reached 4.4V, and then charged again with a constant voltage of 4.45V until the current reached 0.05C, and left to stand for 10 minutes. It was then discharged with a constant current of 0.1C for 7 seconds, and the voltage value was recorded as U1, and then discharged with a current of 1C for 1 second, and the voltage value was recorded as U2.

[0055] The impedance of a lithium-ion battery is calculated using the formula: Impedance of a lithium-ion battery = (U2-U1) / (1C-0.1C), where "1C" is the current value required to completely discharge the lithium-ion battery within one hour.

[0056] Example 1 <Manufacturing of one-dimensional ion-conducting fibers> (1) An ion-conducting substance LATP with a mass m1 = 2.2 g and a polymer polyacrylonitrile (PAN) with a mass m2 = 2.2 g were dissolved in N,N-dimethylformamide as an organic solvent with a volume V = 25 mL, and the mixture was stirred at 40°C until homogeneous to obtain a spinning solution. The mass concentration of the spinning solution was 17.8%. After obtaining fibers from the spinning solution by electrospinning, the fibers were dried at 80°C for 12 hours and allowed to stand. The volume-average particle size of the ion-conducting substance was 300 nm. The parameters during the electrospinning process were a negative voltage of -4 kV, a positive voltage of 18 kV, a fluid delivery rate of 0.3 mL / h, a distance of 20 cm between the collection plate and the spinning needle, and a rotation speed of 2000 rpm for the collection drum.

[0057] (2) The fibers were pre-oxidized in an air furnace, and then heat-treated in a nitrogen gas atmosphere to obtain one-dimensional ion-conducting fibers. The pre-oxidation temperature was T1 = 230°C, the time was t1 = 1h, and the heating rate was S1 = 1°C / min. The heat treatment temperature was T2 = 800°C, the time was t2 = 4h, and the heating rate was S2 = 2°C / min.

[0058] <Manufacturing of positive electrode pieces> Lithium iron phosphate (LFP), the positive electrode active material, Super P, the conductive agent, polyvinylidene fluoride (PVDF), the binder, and the one-dimensional ion-conducting fibers prepared above were mixed in a mass ratio A = 96.5:1.0:1.5:1.0. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, which was then uniformly stirred under vacuum to obtain the positive electrode slurry. The positive electrode slurry was uniformly applied to one surface of a 12 μm thick aluminum foil positive electrode current collector, dried at 90°C, and a load capacity of 3 mAh / cm² was obtained. 2 A positive electrode piece was obtained in which a positive electrode material layer was coated on one side. The thickness H1 of the positive electrode material layer coated on one side was 48 μm, and the thickness H2 of the positive electrode piece was 60 μm. After drying at 90°C, it was cold-pressed and cut into circular positive electrode pieces with a diameter of 14 mm, and then set aside.

[0059] <Negative electrode piece> A lithium copper composite foil with a thickness of 50 μm (manufacturer: China Energy Lithium Co., Ltd.) was used as the negative electrode piece, and it was cut into circular negative electrode pieces with a diameter of 18 mm and set aside.

[0060] <Separator> A porous polyethylene film with a thickness of 15 μm (provided by Cellguard Co., Ltd.) was used.

[0061] <Manufacturing of electrolyte solution> First, dioxolane (DOL) and dimethyl ether (DME) were mixed in a 1:1 volume ratio under a dry argon gas atmosphere to obtain an organic solvent. Then, bis(trifluoromethanesulfonyl)imide lithium (LiTFSI), a lithium salt, was added to the organic solvent, dissolved, and mixed uniformly to obtain an electrolyte with a lithium salt concentration of 1 mol / L.

[0062] <Manufacturing of lithium-ion batteries> In a glove box under a dry argon gas atmosphere, the negative electrode case, negative electrode piece, separator, positive electrode piece, and positive electrode case were arranged from bottom to top in that order. Electrolyte was added, and the battery was packaged using a packaging machine to obtain a lithium-ion button cell. The negative electrode case and positive electrode case were circular cavities made of steel. The amount of electrolyte added was 10% of the mass of the lithium-ion battery.

[0063] Examples 2 to 23 The relevant manufacturing parameters were adjusted according to Table 1, and otherwise, the process was the same as in Example 1. In Example 21, the manufactured one-dimensional ion-conducting fibers were ground for 1 hour in a grinder (manufacturer: Hefei Kejing Materials Technology Co., Ltd., model number: MSK-SFM-15) and then used for <production of positive electrode pieces>.

[0064] Comparative Example 1 In the manufacturing process of the positive electrode piece, no one-dimensional ion-conducting fibers were added, and the ratio of A was set to 97.5:1.0:1.5; otherwise, the process was the same as in Example 1.

[0065] Comparative Example 2 In the manufacturing process of the positive electrode piece, no one-dimensional ion-conducting fibers were added, and the mass ratio of LFP, conductive agent, and binder was set to A = 97.5:1.0:1.5. Otherwise, the process was the same as in Example 5.

[0066] Comparative Example 3 In the manufacturing process of the positive electrode piece, no one-dimensional ion-conducting fibers were added, and the mass ratio of LFP, conductive agent, and binder was set to A = 97.5:1.0:1.5. Otherwise, the process was the same as in Example 7.

[0067] Comparative Examples 4-6 In the process of manufacturing the positive electrode piece, LATP, LLTO, and LLZTO were used in order instead of one-dimensional ion-conducting fibers, and otherwise the process was the same as in Example 1.

[0068] Comparative Examples 7-9 The relevant manufacturing parameters were adjusted according to Table 1, and otherwise the process was the same as in Example 1.

[0069] The relevant manufacturing parameters and characteristic test results for each example and comparative example are shown in Table 1.

[0070] [Table 1-1] [Table 1-2] [Table 1-3]

[0071] As can be seen from Examples 1 to 23 and Comparative Examples 1 to 6, adding one-dimensional ion-conducting fibers to the positive electrode piece increases the number of cycles and reduces the impedance of the lithium-ion battery. Thus, by adopting the positive electrode piece provided in the present invention, the cycle characteristics of the lithium-ion battery are improved and the impedance is reduced. This demonstrates that interfacial impedance is reduced and the electrochemical properties of the lithium-ion battery are improved.

[0072] As can be seen from Examples 1 to 4 and Comparative Example 7, by further increasing the ratio Y of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material, it is possible to further increase the number of cycles of the lithium-ion battery and further reduce the impedance. However, as can be understood, increasing the ratio Y of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material reduces the content of the positive electrode active material and thus reduces the energy density of the lithium-ion battery. Thus, by controlling the ratio Y of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material within the range of the present invention, the cycle characteristics of the lithium-ion battery can be improved, its impedance reduced, and the impact on the energy density is not significant. As can be seen from Examples 1, 18 to 20 and Comparative Example 8, the diameter D of the one-dimensional ion-conducting fiber in Comparative Example 8 is not within the range of the present invention, resulting in a small number of cycles and high impedance. Thus, by controlling the diameter D of the one-dimensional ion-conducting fiber within the range of the present invention, the cycle characteristics of the lithium-ion battery can be improved and its impedance reduced. As can be seen from Examples 1 to 4, Examples 18 to 20, and Comparative Example 9, the ratio Y of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material and the diameter D of the one-dimensional ion-conducting fiber in Comparative Example 9 are both outside the range of the present invention. This indicates that the low content of the positive electrode active material reduces the energy density of the lithium-ion battery, resulting in a low number of cycles and high impedance, which means that the cycle characteristics, impedance, and energy density of the lithium-ion battery cannot be reconciled. Thus, by adding one-dimensional ion-conducting fibers to the positive electrode piece and bringing the diameter D of the one-dimensional ion-conducting fiber, aspect ratio X, and the ratio Y of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material within the range of the present invention, the number of cycles of the lithium-ion battery can be increased, the impedance can be reduced, and the energy density can be reconciled.As demonstrated, by using the positive electrode piece provided by the present invention, it is possible to improve the cycle characteristics of a lithium-ion battery, reduce its impedance, and simultaneously improve the energy density of the lithium-ion battery, that is, to improve the electrochemical properties of the lithium-ion battery.

[0073] Specifically, as shown in Figure 3, the lithium-ion battery in Example 16 retained less than 80% of its capacity after 401 cycles, while the lithium-ion battery in Comparative Example 3 retained less than 80% of its capacity after 141 cycles. Thus, the lithium-ion battery in the embodiment of the present invention has superior cycle characteristics.

[0074] The length L of the one-dimensional ion-conducting fiber typically affects the electrochemical properties of a lithium-ion battery. As can be seen from Examples 1 to 23, when the length L of the one-dimensional ion-conducting fiber is within the range of the present invention, the resulting lithium-ion battery has a high cycle life and low impedance. Thus, a lithium-ion battery obtained using the positive electrode piece provided by the present invention has good cycle characteristics and low impedance, i.e., good electrochemical properties.

[0075] The mass content W of the one-dimensional ion-conducting fibers typically affects the electrochemical properties of a lithium-ion battery. As can be seen from Examples 1 to 4, when the mass content W of the one-dimensional ion-conducting fibers is within the range of the present invention, the resulting lithium-ion battery has a high cycle life and low impedance. Thus, a lithium-ion battery obtained using the positive electrode piece provided by the present invention has good cycle characteristics and low impedance, i.e., good electrochemical properties.

[0076] The substances contained in one-dimensional ion-conducting fibers typically affect the electrochemical properties of lithium-ion batteries. As can be seen from Examples 1 and 10-11, when the substances contained in the one-dimensional ion-conducting fibers are within the scope of the present invention, the one-dimensional ion-conducting fibers have high ionic conductivity, and the resulting lithium-ion battery has a high cycle life and low impedance. Thus, a lithium-ion battery obtained using the positive electrode piece provided by the present invention has good cycle characteristics and low impedance, i.e., good electrochemical properties.

[0077] The thickness H1 of the positive electrode material layer and the thickness H2 of the positive electrode piece typically affect the electrochemical properties of a lithium-ion battery. As can be seen from Examples 1, 15-17, 22, and 23, when the thickness H1 of the positive electrode material layer and the thickness H2 of the positive electrode piece are within the range of the present invention, the one-dimensional ion-conducting fibers have high ionic conductivity, and the resulting lithium-ion battery has a high cycle life and low impedance. Thus, a lithium-ion battery obtained using the positive electrode piece provided by the present invention has good cycle characteristics and low impedance, i.e., good electrochemical properties.

[0078] In this specification, “includes,” “incorporates,” or any other variation thereof means non-exclusive inclusion, and therefore, a process, method, article, or equipment that includes a set of elements includes not only those elements but also other elements not expressly listed, or elements specific to such a process, method, article, or equipment.

[0079] Each example in this specification is described in a manner relevant to its own context, and similar or identical parts may be referenced between the examples. Each example is described primarily in terms of its differences from the others.

[0080] The foregoing description represents preferred embodiments of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are also included within the scope of protection of the present invention.

Claims

1. It is a positive electrode piece, The positive electrode current collector includes a positive electrode material layer provided on at least one surface of the positive electrode current collector, The positive electrode material layer comprises one-dimensional ion-conducting fibers and a positive electrode active material. The aforementioned one-dimensional ion-conducting fiber has a diameter of 0.1 μm to 10 μm and an aspect ratio of 1.5 to 20000. The ratio of the mass of the one-dimensional ion-conducting fiber to the mass of the positive electrode active material is 0.01:1 to 0.05:

1. The positive electrode piece is characterized in that the one-dimensional ion-conducting fiber includes a carbonized fiber of a polymer fiber containing an ion-conducting substance and a polymer.

2. The positive electrode piece according to claim 1, characterized in that the one-dimensional ion-conducting fiber has a diameter of 0.1 μm to 2 μm.

3. The positive electrode piece according to claim 1, characterized in that the length of the one-dimensional ion-conducting fiber is 1 μm to 1000 μm.

4. The positive electrode piece according to claim 1, characterized in that the mass content of the one-dimensional ion-conducting fibers is 1% to 15% with respect to the mass of the positive electrode material layer.

5. The ionic conductivity of the aforementioned one-dimensional ion-conducting fiber is 1 × 10⁻⁶ -６ The positive electrode piece according to claim 1, characterized in that it is S / cm to 1 × 10² S / cm.

6. The ion-conducting material comprises at least one of LATP, LLZO, LLTO, LLZTO, LAGP, and doped compounds of these compounds. The doping element of the doped compound comprises at least one of Al, Ge, and Si. The polymer comprises at least one of polyacrylonitrile, polyaniline, polyfluoroethylene, polymethyl methacrylate, and polyacrylic acid. The ratio of the mass of the ion-conducting material to the mass of the polymer is 1:2 to 1:

1. The positive electrode piece according to claim 1, characterized in that

7. The positive electrode piece according to claim 1, characterized in that the positive electrode active material comprises at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium-rich manganese material.

8. The positive electrode piece according to claim 1, characterized in that the thickness of the positive electrode material layer is 3 μm to 195 μm, and the thickness of the positive electrode piece is 15 μm to 200 μm.

9. The positive electrode piece according to claim 1, characterized in that the one-dimensional ion-conducting fiber has a diameter of 0.1 μm to 2 μm and an aspect ratio of 5 to 200.

10. The positive electrode piece according to claim 1, characterized in that the length of the one-dimensional ion-conducting fiber is 1 μm to 100 μm.

11. An electrochemical apparatus comprising a solid electrolyte and a positive electrode piece according to any one of claims 1 to 10.

12. An electronic apparatus including the electrochemical apparatus described in claim 11.

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