Nickel-Based Cathode Particle Composition for Crack-Resistant Batteries
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Solution Overview
Problem
Conventional lithium nickel cobalt manganese oxide positive electrode active materials face issues with particle breakage and cracks during manufacturing and charging/discharging, leading to increased side reactions with the electrolyte and degradation of lifespan characteristics.
Innovation Solution
A positive electrode active material comprising lithium nickel-based transition metal oxides with specific particle size and roundness characteristics, including large secondary particles and small single or quasi-single particles, is developed to minimize particle breakage and cracks, thereby reducing side reactions and improving high-temperature lifespan and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel cobalt manganese oxide is used in the form of a secondary particle with a large number of primary particles aggregated, then the capacity characteristics are improved, but particle breakage and cracks occur during manufacturing and charging/discharging processes
Solution Approach 1:
The patent divides the positive electrode active material into two distinct particle size fractions: large particles (D50: 5-30 μm) for high capacity and small particles (D50: 1-5 μm) for structural integrity. This segmentation allows each fraction to fulfill different functional requirements, resolving the contradiction between capacity and reliability.
Solution Approach 2:
The patent applies specific parameter thresholds to control particle characteristics: roundness (R50: 0.7-0.95, R10: 0.6-0.90), Z value (1.0-9.0), and NSF (0.1-0.9). By precisely controlling these parameters, the patent optimizes the balance between particle packing density (capacity) and resistance to breakage (reliability).
2Volume of stationary object
If the positive electrode active material contains a large number of aggregated primary particles, then the rolling density is improved, but cracks occur inside particles during charging and discharging
Solution Approach 1:
The patent controls the roundness parameters (R50: 0.7-0.95, R10: 0.6-0.90) to optimize particle shape for both dense packing and crack resistance. The Z value (1.0-9.0) and NSF (0.1-0.9) parameters further refine the particle morphology distribution to prevent internal stress concentration during electrochemical cycling.
Solution Approach 2:
The patent creates a composite particle size distribution system where large particles provide volume efficiency and small particles fill interstitial spaces. This composite approach achieves high rolling density while the small particles act as stress buffers to prevent crack propagation in the larger particles.
3Ease of manufacture
If particle breakage occurs during electrode manufacturing, then the contact area with electrolyte increases, but side reactions with electrolyte increase and lifespan characteristics deteriorate
Solution Approach 1:
The patent performs preliminary classification of particles by size and roundness before electrode manufacturing. By pre-sorting particles into large (D50: 5-30 μm) and small (D50: 1-5 μm) fractions with controlled roundness parameters, the patent prevents breakage during the rolling process, thereby maintaining low side reaction rates and extended lifespan.
Data Source
AI summary
The present disclosure relates to a positive electrode active material including: a lithium nickel-based transition metal oxide with a large particle diameter and a lithium nickel-based transition metal oxide with a small particle diameter. The lithium nickel-based transition metal oxide with a large particle diameter is a secondary particle. The lithium nickel-based transition metal oxide with a small particle diameter is a single particle formed of one nodule and/or a quasi-single particle that is a composite of 30 or less nodules. The lithium nickel-based transition metal oxide with a large particle diameter has a D50 of 5 μm to 30 μm, a Z value defined by factors of roundness distribution characteristics of 1.0 to 9.0, and a negative skewness factor (NSF) of 0.1 to 0.9. Use of the positive electrode active material in a lithium secondary battery results in improved lifespan and/or output characteristics of the battery.