Lithium Cobalt Oxide Cathode Composition for Stable Cycle Capacity

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Solution Overview

Problem

Lithium-ion secondary batteries face challenges in discharge capacity, cycle performance, reliability, and safety, particularly in positive electrode active materials, which degrade during charge and discharge cycles.

Innovation Solution

A positive electrode active material composed of lithium cobalt oxide with magnesium and aluminum additives, having a layered rock-salt crystal structure, is developed. The surface portion of the material contains a higher concentration of magnesium and nickel, while the inner portion has a lower concentration, stabilizing the crystal structure and inhibiting degradation during cycling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium cobalt oxide is used as positive electrode active material to achieve high discharge capacity, then discharge capacity is improved, but cycle performance deteriorates due to crystal structure degradation during charge and discharge cycles

Engineering Contradiction:

Improvedischarge capacityVSAvoidcycle performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a non-uniform distribution of magnesium and nickel elements within the lithium cobalt oxide crystal structure. The surface portion contains a higher concentration of magnesium and nickel compared to the inner portion, which stabilizes the crystal structure at critical regions during charge and discharge cycles while maintaining high discharge capacity throughout the material.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining lithium cobalt oxide with magnesium and nickel elements to form a multi-element composite structure. This composite approach creates a material that integrates the high capacity characteristics of lithium cobalt oxide with the structural stability provided by magnesium and nickel, particularly at the crystal surface regions.

Inventive Principle:

Principle #40Composite materials

2Productivity

If charging and discharging are repeated to utilize battery capacity, then energy output is improved, but crystal structure breaks down leading to performance degradation

Engineering Contradiction:

Improveenergy outputVSAvoidcrystal structure stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-stabilizing the crystal structure with magnesium and nickel elements before the battery undergoes charge and discharge cycling. This preliminary structural reinforcement prevents crystal breakdown during subsequent cycling operations, allowing the battery to maintain its energy output capability over extended use.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If magnesium and nickel are added to stabilize crystal structure, then cycle performance is improved, but discharge capacity may be reduced due to dilution of active lithium cobalt oxide

Engineering Contradiction:

Improvecycle performanceVSAvoiddischarge capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent resolves this contradiction by concentrating magnesium and nickel additives in the surface portion of the crystal structure rather than uniformly distributing them throughout. This localized approach stabilizes the crystal structure where it is most vulnerable during cycling while minimizing the dilution effect on the bulk lithium cobalt oxide that provides discharge capacity.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The material maintains high discharge capacity and prevents structural breakdown, ensuring a highly safe and reliable secondary battery performance even with repeated charging and discharging.

Implementation Method 1

The surface portion of the material contains a higher concentration of magnesium and nickel, while the inner portion has a lower concentration, stabilizing the crystal structure and inhibiting degradation during cycling

Methodology Applied

Scientific EffectCrystal structure stabilization:

Implementation Method 2

X-ray diffraction (XRD) is one of methods used for analysis of the crystal structure of a positive electrode active material

Methodology Applied

Scientific EffectX-ray diffraction: X-Ray

Implementation Method 3

For Rietveld analysis, the analysis program RIETAN-FP can be used, for example

Methodology Applied

Scientific EffectRietveld analysis:

Data Source

PatentUS20250279424A1Positive electrode active material, positive electrode, secondary battery, electronic device, and vehicle

Publication Date: 2025.09.04 SEMICON ENERGY LAB CO LTD

AI summary

A positive electrode active material which inhibits a decrease in discharge capacity during charge and discharge cycles and a secondary battery which includes the positive electrode active material are provided. The secondary battery includes a positive electrode active material. The positive electrode active material contains lithium cobalt oxide. A total mass of magnesium oxide and tricobalt tetraoxide estimated by Rietveld analysis of a pattern obtained by powder X-ray diffraction of the positive electrode active material is less than or equal to 3% with respect to a mass of the lithium cobalt oxide. A volume resistivity of a powder of the positive electrode active material is higher than or equal to 1.0E+8 Ω·cm and lower than or equal to 1.0E+10 Ω·cm under a pressure of 64 MPa.