Nickel-Rich Cathode Particle Size Control for Battery Durability
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries require positive electrode active materials with high output characteristics and durability, but existing materials face challenges such as particle cracking, reduced capacity retention, and insufficient power output due to aggregated primary particles and high temperature calcination, which affects lithium ion diffusion and charge/discharge efficiency.
Innovation Solution
A positive electrode active material comprising lithium-transition metal composite oxide particles with a layered structure, containing nickel, and having a controlled average particle size and size distribution, which reduces grain boundary interactions and disorder, enhancing durability and power characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of primary particles forming one secondary particle is reduced, then durability is improved by reducing cracks, but output characteristics may be insufficient due to reduced surface area
Solution Approach 1:
The patent changes the particle size parameters from conventional small particles (3-10 μm) to larger particles (10-20 μm average size), which reduces the number of primary particles per secondary particle. This parameter change simultaneously improves durability by reducing crack formation and maintains output characteristics through optimized particle size distribution and surface properties.
2Stability of the object's composition
If high temperature calcination is performed to form the material, then structural stability is improved, but lithium ion diffusion is hindered and charge/discharge efficiency decreases
Solution Approach 1:
The patent performs calcination at a relatively low temperature of 700°C compared to conventional high temperature processes. This temperature parameter change prevents excessive grain growth and maintains a balanced structure that ensures both structural stability and sufficient lithium ion diffusion paths, thereby achieving both structural integrity and high charge/discharge efficiency.
3Power
If primary particles are aggregated to form secondary particles with hollow structure, then BET specific surface area is increased for high output, but cracks occur during pressurization and expansion/shrinkage reducing durability
Solution Approach 1:
The patent optimizes the average particle size to 10-20 μm and controls the particle size distribution (D50/D10 ratio of 1.2-2.0), which creates a balanced structure that provides sufficient surface area for high output while maintaining structural integrity to prevent cracks during battery operation.
Solution Approach 2:
The patent creates a composite structure where primary particles are aggregated into secondary particles with controlled morphology. This composite structure combines the benefits of increased surface area from aggregation with improved durability from optimized particle size and reduced internal stress, achieving both high output and high reliability.
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 achieves high output power characteristics and durability by minimizing particle cracking, maintaining lithium ion diffusion paths, and reducing disorder, thereby improving charge/discharge efficiency and capacity retention.
Implementation Method 1
maintaining lithium ion diffusion paths
Data Source
AI summary
A positive electrode active material for a nonaqueous electrolyte secondary battery includes particles of a lithium-transition metal composite oxide that contains nickel in the composition thereof and has a layered structure. The particles have an average particle size DSEM based on electron microscopic observation in a range of 1 μm to 7 μm in which a ratio D50/DSEM of a 50% particle size D50 in volume-based cumulative particle size distribution to the average particle size based on electron microscopic observation is in a range of 1 to 4, and a ratio D90/D10 of a 90% particle size D90 to a 10% particle size D10 in volume-based cumulative particle size distribution is 4 or less.