Double-sided negative electrode all-solid-state battery

Abstract

To provide an all-solid-state battery that uses double-sided carbon nanowalls as an anode.SOLUTION: In an all-solid-state battery, negative electrodes 2a, 2b are formed by synthesizing carbon nanowalls with a large surface area and good electrical conductivity on both sides of a copper foil sheet, positive electrodes 4a, 4b are provided opposite the negative electrodes 2a, 2b, and solid electrolytes 3a, 3b are provided between the negative electrodes 2a, 2b and the positive electrodes 4a, 4b. By incorporating carbon nanowalls with a large surface area and excellent electrical conductivity into the negative electrodes, the performance of the battery is improved, contributing to improved battery safety and energy efficiency.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a double-sided negative electrode all-solid-state battery. [Background technology]

[0002] Because solid-state batteries do not use liquid electrolytes, they can reduce the risk of fire or explosion caused by overcharging or over-discharging, and are relatively resistant to high temperatures, with stable performance in high-temperature environments, allowing them to be used in a wide range of weather conditions and environments. In addition, they generally have a long life span and can handle a large number of charge and discharge cycles, which can extend the life of the battery and reduce the frequency of replacement.

[0003] In addition, compared to conventional lithium-ion batteries that use liquid electrolytes, all-solid-state batteries are superior in terms of high energy density, safety, and size, can be packed into a very small volume, and can be configured with double-sided anodes.

[0004] Double-sided anode construction in solid-state batteries is a structure of an anode with multiple layers or coatings compared to a conventional single-layer anode, which improves the flow of electrons and the diffusion of ions within the battery, thereby enhancing battery performance.

[0005] In addition, by using double-sided negative electrodes in solid-state batteries, the battery's capacity (power storage capacity) can be increased, and by placing more active material in the negative electrode, the battery can store more electrical energy, reducing the number of times the battery needs to be charged and increasing its energy density.

[0006] Furthermore, the use of double-sided anodes in solid-state batteries allows more energy to be packed into the same size and volume of the battery, which is crucial for space-constrained applications such as mobile devices, electric vehicles and energy storage systems, and helps extend battery life and the driving range of electric vehicles.

[0007] Advances in double-sided anode solid-state battery technology are improving energy efficiency and safety, enabling more efficient and sustainable energy solutions in a variety of fields, including electronic devices, electric vehicles, and renewable energy storage. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2008-239369 A [Patent Document 2] JP 2022-182871 A Summary of the Invention [Problem to be solved by the invention]

[0009] Of these, research on anode materials for both sides has high electronic and ionic conductivity and plays a role in supporting efficient operation of the battery. Therefore, the selection and design of anode materials is a central research topic in the development of new all-solid-state batteries.

[0010] According to the inventors' research, carbon nanowalls (CNWs) are a type of nanocarbon material. Instead of the usual flat surface, they have a vertical wall-like structure that gives them a large surface area. Due to their special structure and high specific surface area, they are suitable for electronic conduction and electrode reactions, and the inventors have found that they are an extremely promising material for use as a double-sided anode material in all-solid-state batteries. [Means for solving the problem]

[0011] Therefore, the present invention proposes an all-solid-state battery in which carbon nanowalls (CNWs) synthesized on both sides of a conductive substrate are used as the negative electrode, a positive electrode is provided opposite the negative electrode, and a solid electrolyte is provided between the positive and negative electrodes.

[0012] Various conductive materials can be used as conductive substrates, but stainless steel, which has excellent corrosion resistance, has low conductivity and is therefore not suitable for high-performance electronic devices and circuits. Copper foil has high conductivity and little energy loss, making it suitable for transmitting electrical signals with high efficiency, and is relatively inexpensive, providing a good balance between performance and cost, so it is commonly used.

[0013] Copper foil is generally used after the copper oxide layer on the surface is removed with an alkali or acid.

[0014] CNWs are carbon nanostructures with a high specific surface area, which has the effect of increasing the reactive surface area. By synthesizing CNWs on the surface of a conductive substrate such as copper foil, a high surface area and electrical conductivity are combined, which is expected to improve the performance and efficiency of the anode.

[0015] The positive electrode affects the output of the battery and must have high electronic conductivity while at the same time being required to efficiently accept lithium ions. Lithium compounds such as LiMnO are used as the material.

[0016] The solid electrolyte is required to efficiently transmit lithium ions, and materials such as lithium oxide ceramics (LiPON) are used for this purpose. Effect of the Invention

[0017] According to the present invention, the performance of the battery can be improved by incorporating carbon nanowalls, which have a large surface area and excellent electrical conductivity, into the double-sided negative electrode.

[0018] In addition, by applying a pouch-type design to the all-solid-state battery of the present invention, (a) the internal structure is relatively simple, so that measurement and operation are easy. This means that the product can be used and maintained easily. (b) A compact design is possible, and the pouch-type design helps to keep the product compact. This is particularly suitable for applications where space is restricted, such as mobile phones, electronic devices, and electric vehicles. (c) By effectively stacking the electrodes and solid electrolyte, a large amount of energy can be stored in a small space. In other words, a high energy density can be achieved, which can contribute to improving the performance of batteries and cells. [Brief description of the drawings]

[0019] [Figure 1] Figure 1 shows the copper foil cut design and size diagram. [Diagram 2] Figure 2 shows the etching of both sides of copper foil. [Diagram 3] Figure 3 is an image of an all-solid-state battery with a double-sided carbon nanowall anode. [Figure 4] Figure 4 shows an SEM image of carbon nanowalls. [Diagram 5] Figure 5 shows the Raman diagram of carbon nanowalls. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] An all-solid-state battery in which a negative electrode is formed by synthesizing carbon nanowalls on both sides of copper foil, a positive electrode LiMnO layer is placed opposite the negative electrode, and a solid electrolyte LiPON layer is placed between the negative electrode and positive electrode LiMnO layer. EXAMPLES

[0021] The present invention will now be described with reference to the illustrated embodiments. Figure 1 shows the cut design and size of copper foil 1, and the copper foil sheet was made into a 5mm x 5mm board. Consider the design of the wiring to be placed on the copper foil sheet, and based on the required wiring pattern, decide which part of the copper foil to cut, and use specialized cutting equipment to make precise cuts and place the 5mm x 5mm copper foil board in the appropriate position, and use this board to connect the wiring.

[0022] Figure 2 shows the etching process to grow carbon nanowalls on the surface of copper foil to form a negative electrode. (a) Preparation of copper foil: A substrate using copper foil 1 is prepared, and this substrate is used to synthesize multilayer carbon nanowalls (CNWs) 2a, 2b, and these CNWs are vertically oriented. The copper foil 1 is washed in an ultrasonic cleaning device with acetone and purified water in that order, and after washing, the residual purified water is removed from the surface of the copper foil with a nitrogen gun. (b) Etching: The washed copper foil 1 is immersed in a solution of NaOH or HCl for about 1 minute, and the surface of the copper foil is etched (corroded). CuO+2HCl⇒CuCl2+H2O(c) Cleaning: After etching, the copper foil is washed again with purified water. (d) Drying: The washed copper foil 1 is dried in nitrogen gas for about 10 minutes. (e) Surface particulate matter: After drying, particulate matter appears on the surface of the copper foil 1.

[0023] FIG. 3 shows the process of forming an all-solid-state battery, in which a copper foil (Cu foil) 1 is used as the negative electrode substrate (current collector) of the all-solid-state battery. Using a plasma CVD (chemical vapor deposition) device, 1 μm-thick CNWs 2a are synthesized on the front side of the copper foil 1 to form a honeycomb-like structure, which continues to grow and become a wall-like structure. A LiPON layer 3a (solid electrolyte) is coated on the CNWs layer 2a to a thickness of 1 micrometer, a LiMnO layer 4a is coated on the positive electrode, and a gold layer 5a is coated as a current collector.

[0024] A similar process is applied to the back side of the copper foil 1, which is coated with CNWs 2b, a LiPON layer 3b, a cathode LiMnO layer 4b, and a gold layer 5b to form wiring 6.

[0025] An all-solid-state battery cell with CNWs on both sides of the copper foil 1 was fabricated, which is a key step in the fabrication of this all-solid-state battery. The honeycomb-like structure of the double-sided CNWs contributes to improving the performance of the all-solid-state battery.

[0026] Double-sided carbon nanowall anodes (CNWs) 2a, 2b are used as anodes in solid-state batteries to transport electrons and lithium ions (Li + ) when charging7 and when discharging8.

[0027] When charging 7, lithium ion (Li + ) moves from the positive electrode material (LiMnO) 4a, 4b to the CNWs 2a, 2b and is accumulated in the CNWs 82a, 2b. At the same time, electrons supplied from the outside are supplied to the CNWs 2a, 2b, causing a chemical reaction.

[0028] During discharge 8, by connecting to an external circuit, electrons flow from the CNWs to the positive electrode materials (LiMnO) 4a and 4b, and at the same time, lithium ions (Li + ) also migrates, and an electrochemical reaction occurs within the positive electrode materials 4a and 4b.

[0029] The solid electrolytes 3a and 3b present between the electrodes are lithium ions (Li + ) and provide electronic conductivity. Solid-state batteries can be repeatedly charged7 and discharged8, allowing the flow of electrons and lithium ions (Li + ) to provide electricity.

[0030] The gold current collectors 5a and 5b collect current and help the movement of electrons in the battery, which is an important function for the electrons inside the battery to be supplied to the external circuit. Gold is a material with excellent electrical conductivity and corrosion resistance, and is used to create high-performance batteries, is chemically stable, has a long life, and is highly reliable.

[0031] These materials play an important role in the advancement of solid-state battery technology, contributing to the development of high-performance solid-state batteries, where elements such as electron delivery, ion conduction and current collection work in harmony to enable efficient and sustainable energy storage solutions.

[0032] These elements are combined to make the pouch-type all-solid-state battery work. The electrical conductivity and chemical reaction properties of the solid electrolytes 3a and 3b are expected to provide high energy density and excellent safety.

[0033] Figure 4 shows a typical scanning electron microscope (SEM) image of CNWs formed on copper foil. This is an observation of the electrolytic copper foil from above, and it can be seen that a thin deposit of material is visible on the surface of the electrolytic copper foil, and curved wall-like structures protrude vertically from the substrate. These curved wall-like structures are composed of carbon atoms. We conduct observations such as SEM to understand the synthesis state and properties.

[0034] Figure 5 shows the Raman spectrum of a typical carbon nanowall. A Raman spectrum is a spectrum obtained when a material scatters light, and provides information about the molecular structure and vibrational modes of the material. -1 Peak around 1,350 cm⁻¹ (D band): This peak is due to defects and incomplete structures, and the D band occurs due to disturbances and defects in the crystal structure within the carbon nanowall. The G band is a peak caused by lattice vibrations of graphene, and is an important characteristic that indicates the crystallinity of a material and the presence of graphene. Peak around 1,350 cm⁻¹ (D band): This peak is due to defects and incomplete structures, and the D band occurs due to disturbances and defects in the crystal structure within the carbon nanowall. [Industrial Applicability]

[0035] In summary, according to the present invention, by incorporating carbon nanowalls with a large surface area and excellent electrical conductivity into a double-sided negative electrode, it is possible to provide an all-solid-state battery with improved battery performance. [Explanation of symbols]

[0036] 1………………Copper foil 2a: Front view of synthesized carbon nanowalls (CNWs) 2b: Synthesized carbon nanowalls (CNWs) on the back side 3a………………Front coated solid electrolyte (LiPON) 3b: Solid electrolyte (LiPON) with backside coating 4a: Front coated positive electrode (LiMnO) 4b: Backside coated cathode (LiMnO) 5a………………Front-coated current collector (gold) 5b: Back-coated current collector (gold) 6………………Wiring 7…………Charging 8………………discharge

Claims

1. An all-solid-state battery characterized by using carbon nanowalls synthesized on both sides of a conductive substrate as a negative electrode, a positive electrode facing the negative electrode, and a solid electrolyte between the positive electrode and the negative electrode.

2. 2. The all-solid-state battery according to claim 1, wherein the substrate is a copper foil.

3. 3. The all-solid-state battery according to claim 2, wherein the copper oxide layers on both sides of the copper foil are removed, and then carbon nanowalls are grown to form a negative electrode.

4. 2. The all-solid-state battery according to claim 1, wherein the positive electrode, the solid electrolyte, and the negative electrode are laminated in a pouch-type design.

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