JP-2026075387-A - Positive electrode active material for lithium-ion secondary batteries

Abstract

[Challenge] Improvement of rate characteristics. [Solution] The positive electrode active material for lithium-ion secondary batteries contains secondary particles. The secondary particles contain three or more primary particles. The secondary particles are formed by the two-dimensional arrangement of three or more primary particles. [Selection Diagram] Figure 1

Inventors

• 大澤 良輔

Assignees

• トヨタ自動車株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (5)

1. Contains secondary particles, The aforementioned secondary particles include three or more primary particles, The secondary particles are formed by arranging three or more of the primary particles in a two-dimensional manner. Positive electrode active material for lithium-ion secondary batteries.
2. The secondary particles include 3 to 20 of the primary particles. The positive electrode active material for a lithium-ion secondary battery according to claim 1.
3. The secondary particles have an in-plane direction and a thickness direction, The aforementioned in-plane direction is any direction perpendicular to the aforementioned thickness direction, Three or more of the primary particles are arranged in the in-plane direction, and Through holes are formed along the thickness direction that penetrate the secondary particles. The positive electrode active material for a lithium-ion secondary battery according to claim 1 or claim 2.
4. 1 < b / a < 5 The relationship is satisfied, The above a indicates the opening diameter of the through hole, and, The above b indicates the Ferret diameter of the primary particle in the thickness direction. The positive electrode active material for a lithium-ion secondary battery according to claim 3.
5. It is a lithium nickel cobalt manganese composite oxide. The positive electrode active material for a lithium-ion secondary battery according to claim 1 or claim 2.

Description

This disclosure relates to a positive electrode active material for lithium-ion secondary batteries. Japanese Patent Publication No. 2023-036570 discloses a ternary cathode material in which primary particles are aggregated to form spherical secondary particles. Japanese Patent Publication No. 2023-036570 This is a conceptual diagram of secondary particles in this embodiment.This is a table showing the experimental results.Figure 3 is a conceptual diagram showing an example of a mixing apparatus. Terminology and Phrases: Geometric terms should not be interpreted strictly. Examples of geometric terms include "parallel,""perpendicular," and "orthogonal." For example, direction, angle, distance, etc., may be relatively distorted within a range where substantially the same or similar function is obtained. Geometric terms may include tolerances, errors, etc., in design, operation, and manufacturing. Dimensional relationships in each figure may not match actual dimensional relationships. Dimensional relationships in each figure may be modified to aid the reader's understanding. For example, length, width, thickness, etc., may be changed. Some components may be omitted. "D50" represents the particle size at which the cumulative frequency in the volume-based particle size distribution (cumulative distribution) reaches 50%. D50 can be measured, for example, by laser diffraction. The "Ferret diameter" refers to the distance between two parallel lines that surround a particle. For example, the Ferret diameter in the thickness direction is measured by sandwiching a particle between two lines perpendicular to the thickness direction. The "opening diameter" indicates the maximum Ferret diameter of the through-hole opening. The maximum Ferret diameter represents the maximum value of the Ferret diameter in the in-plane direction. All numerical values are modified by the term "approximately." "Approximately" can mean, for example, ±5%, ±3%, ±1%, etc. All numerical values may be approximations that vary depending on the application of the technology in question. All numerical values may be expressed with significant figures. Unless otherwise specified, measured values may be the average of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. Generally, the reliability of the average is expected to improve with a larger number of measurements. Measured values may be rounded to the nearest significant figure. Measured values may include errors such as those associated with the detection limits of the measuring device. The stoichiometric compositional formula shows a representative example of a compound. The compound may have a non-stoichiometric composition. For example, " Al₂O₃ " is not limited to compounds with a molar ratio of "Al/O = 2/3". Unless otherwise specified, "Al₂O₃ " indicates a compound containing Al and O in any molar ratio. For example, the compound may be doped with trace elements. Some of the Al and O may be substituted with other elements. Positive electrode active material The positive electrode active material is for lithium-ion secondary batteries. The lithium-ion secondary battery (hereinafter abbreviated as "battery") may be an electrolyte battery or an all-solid-state battery. In all-solid-state batteries, for example, an improvement in rate characteristics can be expected by improving the contact rate between the solid electrolyte and the primary particles. The battery may have any structure. The battery may have, for example, a wound type or a stacked type power generation element. The battery may have, for example, a unipolar structure or a bipolar structure. Figure 1 is a conceptual diagram of secondary particles in this embodiment. The positive electrode active material includes secondary particles 2. The positive electrode active material may also include aggregates (powder) of secondary particles 2. The D50 of the positive electrode active material may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more. The D50 of the positive electrode active material may also be, for example, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. Secondary particles 2 contain three or more primary particles 1. The number of primary particles 1 may be, for example, four or more, six or more, eight or more, ten or more, twelve or more, fourteen or more, sixteen or more, eighteen or more, or twenty or more. The number of primary particles 1 may also be, for example, 25 or less, 23 or less, 21 or less, 19 or less, 17 or less, 15 or less, 13 or less, 11 or less, nine or less, seven or less, or five or less. The number of primary particles 1 represents the average number in ten randomly sampled secondary particles 2. Multiple primary particles 1 are arranged in a two-dimensional manner. From a macroscopic perspective, secondary particles 2 (a collection of primary particles 1) have a platelet shape. The a