Bimodal High-Nickel Cathode Material for Roll-Pressing and Thermal Stability
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Solution Overview
Problem
Lithium-nickel-cobalt-manganese oxides with high nickel content face challenges in roll-pressing density, thermal stability, and lifespan due to particle aggregation and side reactions with electrolytes.
Innovation Solution
A positive electrode material with a bimodal particle size distribution is developed, comprising large-diameter and small-diameter particles. The small-diameter particles are lithium composite transition metal oxides with a nickel content of 80 atm % or greater, in the form of single particles with rock salt phases on their surface, which are mixed with larger particles to enhance roll-pressing density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content (80 at% or greater) is used in lithium-nickel-cobalt-manganese oxide to improve reversible capacity, then capacity properties are enhanced, but thermal stability deteriorates and structural stability decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior maintains high nickel content (80 at% or greater) for high capacity, while the surface is modified with a protective coating layer containing elements such as aluminum, magnesium, or calcium that provide thermal and structural stability. This allows different regions of the particle to have different compositions optimized for their specific functions.
Solution Approach 2:
The patent uses composite materials by combining high-nickel lithium-nickel-cobalt-manganese oxide with surface-modifying materials to create a composite structure. The core provides high capacity while the surface layer provides stability, achieving a synergistic effect that resolves the contradiction between capacity and stability.
2Quantity of substance
If high nickel content (80 at% or greater) is used to improve capacity properties, then reversible capacity increases, but roll-pressing density becomes lower
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution and morphology of the high-nickel oxide. By controlling particle diameter, shape, and size distribution during synthesis, the patent achieves both high capacity and improved roll-pressing density, resolving the contradiction between these two parameters.
3Productivity
If secondary particles are used to improve manufacturing efficiency, then production is simplified, but gaps form between primary particles during cycling causing side reactions with electrolyte
Solution Approach 1:
The patent applies the taking out principle by removing the problematic secondary particle aggregation structure and using only primary particles or controlled agglomerates. This eliminates the gaps between primary particles that cause electrolyte infiltration and side reactions, while maintaining manufacturing efficiency through optimized synthesis processes.
4Volume of stationary object
If strong roll-pressing is applied to increase density, then energy density improves, but current collector breaks and positive electrode material cracks
Solution Approach 1:
The patent applies parameter changes by optimizing particle size, shape, and size distribution to achieve high roll-pressing density without requiring excessive pressing force. By controlling these parameters, the patent achieves high energy density while maintaining structural integrity and avoiding current collector damage.
Data Source
AI summary
A positive electrode material and a method of producing thereof is provided. The positive electrode material having a bimodal particle diameter distribution and including large-diameter particles and small-diameter particles, wherein the small-diameter particle is a lithium composite transition metal oxide in the form of a single particle and containing a rock salt phase formed on a surface portion thereof.