Single-Particle Positive Electrode Material for Crack-Resistant ASSBs
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Solution Overview
Problem
All-solid-state batteries face challenges in achieving high discharge capacity, excellent rate characteristics, and long lifespan due to the weak particle strength and large average particle size of positive electrode active materials, which lead to cracking and poor lithium ion diffusion, especially when subjected to manufacturing pressures and volume changes during battery life.
Innovation Solution
A positive electrode active material with high particle strength (300-1500 MPa) and small average particle size (10 μm or less) is developed, manufactured using a transition metal composite precursor and lithium source through primary and secondary heat treatments, ensuring single particle form and enhanced lithium ion conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the positive electrode active material uses conventional particle sizes and structures, then the manufacturing process is simpler, but the particle strength is weak and cracking occurs during battery operation
Solution Approach 1:
The patent applies preliminary action by performing primary heat treatment to form precursor particles with controlled morphology and size distribution before the final sintering step. This preliminary structuring ensures high particle strength is achieved during subsequent processing without requiring complex manufacturing interventions later, as the particles are pre-configured to withstand manufacturing pressures and operational stresses
Solution Approach 2:
The patent utilizes parameter changes by systematically optimizing heat treatment temperature ranges (600-900°C for primary, 800-1000°C for secondary), particle size distributions (1-10 μm), and sintering conditions to transform the particle structure. These controlled parameter variations during processing develop the desired high strength characteristics while maintaining manufacturing feasibility through established thermal processing techniques
2Speed
If the positive electrode active material has large particle size, then the material is easier to handle and manufacture, but lithium ion diffusion is poor and rate characteristics deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the particle size distribution into specific ranges (1-10 μm) and using multi-stage heat treatment to create heterogeneous particle structures. This segmentation enables sufficient lithium ion diffusion pathways while maintaining particles large enough for practical handling and manufacturing, resolving the contradiction between diffusion speed and manufacturability
Solution Approach 2:
The patent implements local quality by creating particles with optimized internal structures through controlled sintering, where the exterior maintains sufficient size for handling while the interior develops optimized diffusion pathways. The differential heat treatment creates local structural variations that enhance lithium ion diffusion without requiring uniform reduction of overall particle size
3Reliability
If the positive electrode active material undergoes volume changes during battery cycling, then the electrochemical reaction is active, but particle cracking occurs due to weak strength
Solution Approach 1:
The patent applies beforehand cushioning by developing a dense, sintered particle structure with optimized strength characteristics before the battery enters operational cycling. The secondary heat treatment creates a robust particle framework that can withstand subsequent volume expansion and contraction during charge-discharge cycles, preventing cracking and maintaining reliability throughout the battery lifespan
4Strength
If the positive electrode active material has small particle size, then lithium ion diffusion is improved and rate characteristics are excellent, but the particle strength becomes insufficient and cracking occurs
Solution Approach 1:
The patent applies composite materials principles by creating a multi-phase sintered structure through sequential heat treatments, where different crystalline phases and microstructural features combine to achieve both high strength and good ionic conductivity. The composite nature of the sintered particle provides mechanical robustness while maintaining diffusion pathways, simultaneously satisfying both requirements
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 high particle strength and small size of the active material prevent cracking and improve lithium ion diffusion, resulting in high discharge capacity, excellent rate characteristics, and extended lifespan by maintaining contact with the solid electrolyte and reducing resistance.
Implementation Method 1
a positive electrode active material having high particle strength and a small average particle size
Implementation Method 2
excellent rate characteristics and long lifespan characteristics... improve lithium ion diffusion
Implementation Method 3
producing a lithium metal oxide in the form of a single particle having a particle strength of 300 to 1500 MPa and an average particle size of 10 μm or less through secondary heat treatment
Data Source
AI summary
A positive electrode active material, an all-solid-state battery comprising same, and a method for manufacturing same are proposed. The positive electrode active material may include a lithium metal oxide in the form of single particles having a particle strength of 300 MPa to 1500 MPa and an average particle diameter of at most 10 μm. Since the positive electrode active material is in the form of single particles having a high particle strength of at least 300 MPa and a small average particle diameter of at most 10 μm as indicated above, cracks may not form or may be delayed even when pressure is applied during the manufacture of the positive electrode or structural stress is applied over the lifespan of the battery.