Cathode Active Material Structure to Suppress Electrolyte Side Reactions

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Solution Overview

Problem

Lithium secondary batteries face challenges with mechanical and chemical stability, leading to side reactions with electrolytes and reduced performance, particularly due to high surface area and residual lithium content in cathode active materials.

Innovation Solution

A cathode active material comprising lithium composite oxide particles with a secondary particle structure and specific lithium conduction pathways, where primary particles with defined angles and a high nickel mole fraction are aggregated, reducing electrolyte penetration and surface area, thereby enhancing mechanical strength and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high nickel content lithium composite oxide is used to increase capacity, then battery capacity is improved, but mechanical and chemical stability deteriorates

Engineering Contradiction:

Improvebattery capacityVSAvoidmechanical and chemical stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The cathode active material is divided into primary particles (3-10 μm) that aggregate to form secondary particles (10-20 μm). This segmentation allows high nickel content (0.6-0.95 mole fraction) to be achieved while maintaining stability through the aggregated structure, where multiple smaller particles work together to provide both high capacity and improved mechanical strength compared to single large particles.

Inventive Principle:

Principle #1Segmentation

2Strength

If specific particle arrangement with 45°-90° angles is implemented, then mechanical strength is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvemechanical strengthVSAvoidparticle arrangement precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The invention specifies a particular angular parameter range (45°-90°) for the arrangement of primary particles within secondary particles. This parameter change creates an optimized structure where lithium conduction pathways form at appropriate angles, improving mechanical strength while the defined range provides clear manufacturing guidance rather than requiring extreme precision.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If secondary particle structure with aggregated primary particles is used, then electrolyte penetration is reduced, but surface area decreases

Engineering Contradiction:

Improveelectrolyte penetrationVSAvoidsurface area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The secondary particle structure acts as a protective arrangement where primary particles are aggregated in a specific configuration. This structure reduces electrolyte penetration by creating a more compact arrangement with controlled surface exposure, while the aggregated nature maintains sufficient total surface area for lithium conduction through the defined angular pathways.

Inventive Principle:

Principle #30Flexible shells and thin films

4Ease of manufacture

If water washing process is omitted, then manufacturing complexity is reduced, but residual lithium content increases

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidresidual lithium content

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The specific particle arrangement and lithium conduction pathway structure enable the material to self-manage residual lithium through controlled diffusion pathways. The 45°-90° angular configuration creates natural drainage and conduction paths that facilitate lithium removal during drying without requiring water washing, allowing the material to effectively self-clean through its structural design.

Inventive Principle:

Principle #25Self-service

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 solution effectively suppresses side reactions, improves mechanical safety, and allows for the omission of the water washing process during manufacturing, resulting in a lithium secondary battery with enhanced stability and performance.

Implementation Method 1

the primary particles respectively include a lithium conduction pathway through which lithium ions are diffused

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20250023044A1Cathode active material and lithium secondary battery including the same

Publication Date: 2025.01.16 SK ON CO LTD

AI summary

The cathode active material according to embodiments of the present invention includes a lithium composite oxide particle having a form of secondary particle in which a plurality of primary particle are aggregated, wherein the primary particles respectively include a lithium conduction pathway through which lithium ions are diffused. Wherein the primary particles include a first particle, and the first particle has an angle of 45° to 90° formed by a direction from a center of the first particle to a center of the lithium composite oxide particle and a direction of the lithium conduction pathway included in the first particle, wherein a ratio of the number of the first particles among the primary particles located on a surface of the lithium composite oxide particle is 20% or more.