Solid-State Lithium Battery Cathode for Crack-Resistant Cycling

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Solution Overview

Problem

Lithium secondary batteries face issues with mechanical integrity due to volume changes during repeated charge and discharge cycles, leading to cathode damage and performance degradation.

Innovation Solution

Incorporating lithium-metal oxide particles with a compressive fracture strength of 1,500 MPa or more and a single particle form, along with a sulfide-based solid electrolyte, to enhance mechanical durability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cathode materials are used in lithium secondary batteries, then the battery can be manufactured with standard materials, but the cathode suffers from mechanical damage and cracking due to volume changes during charge-discharge cycles

Engineering Contradiction:

Improvecathode mechanical integrityVSAvoidcathode fracture resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the physical and chemical parameters of the cathode material by using lithium-metal oxide particles with compressive fracture strength of at least 1,500 MPa and specific particle size distribution (D50 of 1-10 μm). This parameter change enables the cathode to withstand volume changes during charge-discharge cycles without mechanical damage, resolving the contradiction between reliability and strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure consisting of lithium-metal oxide particles combined with a sulfide-based solid electrolyte layer. This composite material system provides both the necessary mechanical strength to resist cathode cracking and the electrochemical functionality, thereby improving reliability while maintaining strength.

Inventive Principle:

Principle #40Composite materials

2Duration of action of moving object

If the battery undergoes repeated charge and discharge cycles, then the battery provides sustained energy storage, but internal pressure increases causing cathode damage and performance degradation

Engineering Contradiction:

Improvebattery cycle lifeVSAvoidinternal battery pressure

Core Design Contradiction:

Duration of action of moving objectVSStress or pressure

Solution Approach 1:

The patent applies beforehand cushioning by incorporating a sulfide-based solid electrolyte layer between the cathode and anode that acts as a buffer to absorb and distribute internal pressure generated during charge-discharge cycles. This prevents pressure concentration that would otherwise cause cathode damage, enabling sustained cycle life while managing internal stress.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the mechanical properties of the battery components by selecting lithium-metal oxide particles with high compressive fracture strength (≥1,500 MPa) and specific particle size characteristics. These parameter changes enable the cathode structure to withstand repeated cycling-induced pressure without degradation, extending duration while controlling stress.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If liquid electrolyte is used in the battery, then the battery achieves good ionic conductivity, but the battery has high explosion risk due to ignition hazard

Engineering Contradiction:

Improvebattery safetyVSAvoidignition risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state parameter of the electrolyte from liquid to solid by using a sulfide-based solid electrolyte. This parameter change eliminates the ignition risk associated with liquid electrolytes while maintaining sufficient ionic conductivity for battery operation, thereby improving safety without introducing harmful factors.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the hazardous liquid electrolyte with a solid electrolyte material that inherently provides safety against ignition. This substitution uses a different material class (solid vs. liquid) that naturally eliminates the explosion risk, achieving the same functional purpose (ionic conduction) with improved safety characteristics.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 minimizes cathode cracking and maintains structural integrity, improving cycle life and performance by reducing internal pressure and enhancing charge and discharge speeds.

Implementation Method 1

the solid electrolyte may serve as an electrolyte that physically separates the cathode and the anode while allowing lithium ions to migrate

Methodology Applied

Scientific EffectIon migration: Diffusion

Implementation Method 2

a cathode which includes lithium-metal oxide particles having a compressive fracture strength of 1,500 MPa or more

Methodology Applied

Scientific EffectCompressive fracture strength: Fracture Mechanics

Data Source

PatentEP4682982A1Lithium secondary battery

Publication Date: 2026.01.21 SK ON CO LTD

Figure 1

AI summary

A lithium secondary battery according to the embodiments of the present disclosure includes a cathode which includes lithium-metal oxide particles having a compressive fracture strength of 1,500 MPa or more and having a single particle form; an anode disposed opposite to the cathode and including a lithium metal layer; and a solid electrolyte layer interposed between the cathode and the anode and including a sulfide-based solid electrolyte.