Positive Electrode Grain-Boundary Structure for High-Voltage Cycling

Solution Overview

Problem

Lithium cobalt oxide-based batteries experience deterioration in charge and discharge cycle properties due to undesirable reactions at the active material surface when charging and discharging in high potential regions, leading to reduced battery reliability.

Innovation Solution

A positive electrode active material is developed with particles that have a grain boundary where the c axes of two regions sandwiching the grain boundary are in reflective symmetry, and the content percentage of such particles is 50% or less, reducing the likelihood of cracking and surface area increase during high potential charging and discharging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium cobalt oxide is charged and discharged in high potential region to increase capacity and energy density, then battery capacity and energy density are improved, but charge and discharge cycle property deteriorates due to undesirable reactions at active material surface

Engineering Contradiction:

Improvebattery capacityVSAvoidcharge and discharge cycle property

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the crystallographic parameter (c-axis orientation) of the lithium cobalt oxide particles. By controlling the orientation relationship between adjacent crystallites (making c-axes substantially parallel), the material maintains structural stability at high potentials while enabling increased capacity and energy density.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite microstructure within the lithium cobalt oxide particle, where multiple crystallites with specific orientation relationships are combined. This composite structure of aligned crystallites provides both the high capacity/energy density and the structural stability needed for good cycle properties.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium cobalt oxide is charged and discharged in high potential region to increase energy density, then battery energy density is improved, but charge and discharge cycle property deteriorates due to surface reactions

Engineering Contradiction:

Improveenergy densityVSAvoidcharge and discharge cycle property

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the crystallographic parameter (c-axis orientation) of the lithium cobalt oxide particles. By controlling the orientation relationship between adjacent crystallites (making c-axes substantially parallel), the material maintains structural stability at high potentials while enabling increased capacity and energy density.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite microstructure within the lithium cobalt oxide particle, where multiple crystallites with specific orientation relationships are combined. This composite structure of aligned crystallites provides both the high capacity/energy density and the structural stability needed for good cycle properties.

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If particles with grain boundaries and reflective symmetry c-axes are present in high content, then crystal structure stability is improved, but manufacturing precision becomes more difficult to control

Engineering Contradiction:

Improvecrystal structure stabilityVSAvoidparticle orientation control

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent specifies a quantitative parameter range (5-50 wt% of particles with the specific grain boundary structure) that balances crystal structure stability with manufacturability. This parameter optimization allows the beneficial orientation relationship to be achieved without requiring excessive manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12300778B2Positive electrode active material, positive electrode, battery, battery pack, electronic device, electric vehicle, power storage device, and power system

Publication Date: 2025.05.13 MURATA MFG CO LTD

AI summary

A battery includes a positive electrode including powder of a positive electrode active material; a negative electrode; and an electrolyte. The powder of the positive electrode active material includes particles, which have a grain boundary and in which c axes of two regions sandwiching the grain boundary are in reflective symmetry, and the particles in the powder of the positive electrode active material have a content percentage of 50% or less.