Solid-State Lithium Battery Cathode Structure Against Cracking

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Solution Overview

Problem

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

Innovation Solution

Incorporation of lithium-metal oxide particles with a compressive fracture strength of 1,500 MPa or more, a single particle form, and a sulfide-based solid electrolyte layer 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 charging and discharging cycles

Engineering Contradiction:

Improvecathode mechanical integrityVSAvoidcathode resistance to cracking

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by modifying the compressive fracture strength of cathode particles from conventional levels to at least 1,500 MPa. This significant increase in mechanical strength parameter enables the cathode to withstand volume changes during charge-discharge cycles without cracking, directly resolving the technical contradiction between reliability and strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining high-strength cathode particles (with compressive fracture strength ≥1,500 MPa) with a solid electrolyte layer. This composite structure provides both the mechanical strength needed to prevent cracking and the electrochemical functionality required for battery operation, addressing the contradiction between maintaining structural integrity and enabling reversible lithium ion transport.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If the cathode structure is made more durable to withstand volume changes, then cycle life is improved, but the complexity of material synthesis and processing increases

Engineering Contradiction:

Improvebattery cycle lifeVSAvoidcathode material synthesis

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The patent achieves improved cycle life by changing the compressive fracture strength parameter of cathode particles to at least 1,500 MPa. This parameter modification allows the cathode to withstand repeated volume changes during charging and discharging, thereby extending battery cycle life while maintaining a relatively straightforward synthesis approach through controlled particle formation processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies segmentation by using discrete cathode particles with controlled size and strength characteristics rather than continuous or aggregated structures. This particle-based approach enables individual particles to withstand volume changes independently, improving overall cathode durability and cycle life while simplifying the manufacturing process through particle formation and assembly.

Inventive Principle:

Principle #1Segmentation

3Strength

If high-strength cathode particles are used to prevent cracking, then mechanical durability is enhanced, but the manufacturing precision requirements for particle strength control increase

Engineering Contradiction:

Improvecathode compressive fracture strengthVSAvoidparticle strength uniformity

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent manages manufacturing precision challenges by establishing a clear target parameter range for cathode particle compressive fracture strength (at least 1,500 MPa). This quantified parameter specification enables controlled synthesis processes to produce particles with consistent high strength, balancing the need for enhanced mechanical durability with achievable manufacturing precision through process optimization.

Inventive Principle:

Principle #35Parameter changes

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 stress and enhancing durability.

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 strength: Fracture Mechanics

Data Source

PatentUS20260018656A1Lithium secondary battery

Publication Date: 2026.01.15 SK ON CO LTD

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.