KR-102963280-B1 - Cathode active materials, secondary batteries, electronic devices, and vehicles

Abstract

The present invention provides a positive electrode active material for a lithium-ion secondary battery having high capacity and excellent charge-discharge cycle characteristics. The positive electrode active material comprises lithium, cobalt, oxygen, and magnesium, wherein the compound is represented by a layered rock salt-type structure, the compound is represented by a space group R-3m, the compound is a composite oxide having lithium and cobalt in which magnesium is substituted at the lithium position and the cobalt position, the compound is a particle, the substituted magnesium is present in a large amount in the region up to 5 nm from the surface of the particle compared to the region deeper than 10 nm from the surface, and the magnesium substituted at the lithium position is more abundant than the magnesium substituted at the cobalt position.

Inventors

• 몸마 요헤이
• 미카미 마유미
• 오치아이 데루아키
• 나리타 가즈헤이
• 사이토 죠

Assignees

• 가부시키가이샤 한도오따이 에네루기 켄큐쇼

Dates

Publication Date

20260508

Application Date

20191107

Priority Date

20181116

Claims (15)

1. As a positive electrode active material having a compound having lithium, cobalt, oxygen, and magnesium, The above compound does not contain manganese, and The above compound is represented by the space group R-3m, and The above compound is a compound in which magnesium is substituted at the lithium and cobalt positions in a complex oxide having lithium and cobalt, and The above compound is a particle, and Magnesium substituted at lithium and cobalt positions is present in large quantities in the region from the surface of the particle to a depth of 5 nm compared to the region 10 nm or deeper from the surface of the particle, and A positive electrode active material in which magnesium substituted at the lithium position is more abundant than magnesium substituted at the cobalt position.
2. In Article 1, A positive electrode active material having more fluorine.
3. In Article 1, The above compound has a packing depth in which the coordinates of cobalt in the unit cell are (0, 0, 0.5), the coordinates of oxygen are (0, 0, x), and 0.20≤x≤0.25, A positive active material having a difference of 2.5% or less from the volume of the unit cell at the above-mentioned charging depth and the volume of the unit cell when the charging depth is 0.
4. As a secondary battery, A secondary battery having the positive active material described in claim 1.
5. As an electronic device, An electronic device having a secondary battery as described in claim 4 and a display unit.
6. As a vehicle, A vehicle having a secondary battery and an electric motor as described in Clause 4.
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Description

Cathode active materials, secondary batteries, electronic devices, and vehicles One embodiment of the present invention relates to an article, a method, or a method of manufacturing. Alternatively, the present invention relates to a process, a machine, a product, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a capacitor, a lighting device, an electronic device, or a method of manufacturing the same. In particular, it relates to a positive electrode active material usable in a secondary battery, a secondary battery, and an electronic device having a secondary battery. Furthermore, in this specification, the term "energy storage device" refers to all elements and devices having an energy storage function. Examples include batteries (also referred to as secondary batteries), such as lithium-ion secondary batteries, lithium-ion capacitors, and electric double-layer capacitors. Furthermore, in this specification, the term "electronic device" refers to any device having a storage device, and electro-optical devices having a storage device, information terminal devices having a storage device, etc., are all electronic devices. In recent years, the development of various energy storage devices, such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries, has been actively underway. In particular, high-output, high-energy-density lithium-ion secondary batteries are in demand for portable information terminals such as mobile phones, smartphones, tablets, and laptop computers, as well as portable music players, digital cameras, medical devices, and next-generation clean energy vehicles (hybrid electric vehicles (HEV), electric vehicles (EV), plug-in hybrid electric vehicles (PHEV), etc.), and have become indispensable in the modern information society as a rechargeable energy source. The characteristics required for lithium-ion secondary batteries include improved energy density, improved cycle characteristics, and enhanced safety and long-term reliability in various operating environments. Therefore, improvements to the cathode active material are being considered with the aim of improving the cycle characteristics and increasing the capacity of lithium-ion secondary batteries (Patent Documents 1 and 2). In addition, research on the crystal structure of the cathode active material is also being conducted (Non-patent Documents 1 to 3). X-ray diffraction (XRD) is one of the techniques used to analyze the crystal structure of anode active materials. The analysis of XRD data can be performed by using the ICSD (Inorganic Crystal Structure Database) introduced in Non-Patent Literature 5. In addition, as shown in Non-Patent Literature 6 and Non-Patent Literature 7, energy corresponding to the crystal structure, composition, etc. of a compound can be calculated by using first-principles calculations. FIG. 1 is a diagram illustrating the charging depth and crystal structure of a positive electrode active material of one embodiment of the present invention. Figure 2 is a diagram illustrating the filling depth and crystal structure of a conventional positive electrode active material. Figure 3 is an XRD pattern calculated from the crystal structure. FIG. 4 (A) is a diagram illustrating the crystal structure of a positive electrode active material of one embodiment of the present invention. FIG. 4 (B) is a diagram illustrating the magnetism of a positive electrode active material of one embodiment of the present invention. Figure 5 (A) is a diagram illustrating the crystal structure of a conventional positive active material. Figure 5 (B) is a diagram illustrating the magnetism of a conventional positive active material. Figure 6 (A) is a diagram illustrating the crystal structure. Figure 6 (B) is a diagram illustrating the crystal structure. Figure 6 (C) is a diagram illustrating the crystal structure. Figure 7 (A) is a diagram illustrating the crystal structure. Figure 7 (B) is a diagram illustrating the crystal structure. Figure 8 (A) is a diagram illustrating the crystal structure. Figure 8 (B) is a diagram illustrating the crystal structure. Figure 9 (A) is a diagram illustrating the crystal structure. Figure 9 (B) is a diagram illustrating the crystal structure. Figure 9 (C) is a diagram illustrating the crystal structure. Figure 10 (A) is a diagram illustrating the crystal structure. Figure 10 (B) is a diagram illustrating the crystal structure. Figure 11 (A) is a diagram illustrating the crystal structure. Figure 11 (B) is a diagram illustrating the crystal structure. Figure 11 (C) is a diagram illustrating the crystal structure. FIG. 12 is a drawing illustrating an example of a method for manufacturing a positive electrode active material of one form of the present invention. FIG. 13 is a drawing illustrating another example of a method for manufacturing a positive electrode active material of one f