Single-Particle High-Ni NCM Cathode for Thermal Stability
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Solution Overview
Problem
Conventional high-Ni NCM-based lithium composite transition metal oxides face challenges with low structural and chemical stability, high gas generation, and poor thermal stability due to large specific surface area and lithium by-product formation, limiting their use in high-capacity applications.
Innovation Solution
A lithium composite transition metal oxide composed of nickel, cobalt, and manganese, with a single particle structure, incorporating particle growth-promoting elements like strontium, zirconium, magnesium, or aluminum, is prepared through specific sintering processes to reduce surface area and lithium by-products, enhancing stability and thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-Ni NCM-based lithium composite transition metal oxide is used to achieve high capacity, then capacity is improved, but structural stability and chemical stability deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior maintains high Ni content (65-95 mol%) for high capacity while the surface layer contains different composition for stability. This spatial differentiation of material properties resolves the contradiction between bulk capacity and surface stability.
Solution Approach 2:
The patent uses composite materials by combining high-Ni NCM-based lithium composite transition metal oxide with aluminum hydroxide coating layer. This composite structure integrates the high capacity characteristics of Ni-rich material with the protective and stabilizing properties of aluminum hydroxide, simultaneously achieving high capacity and improved stability.
2Ease of manufacture
If conventional NCM-based lithium composite transition metal oxide with secondary particle structure is used, then manufacturing is simplified, but specific surface area increases and particle strength decreases
Solution Approach 1:
The patent applies segmentation by dividing the secondary particle into multiple primary particles (1-5 μm diameter) that aggregate to form the larger secondary structure. This segmentation reduces the specific surface area compared to fully dispersed primary particles while maintaining manufacturability through the aggregated structure.
Solution Approach 2:
The patent uses nested doll principle by having primary particles nested within the secondary particle structure. The primary particles (smaller units) are contained within and aggregated to form the secondary particle (larger structure), creating a hierarchical nested arrangement that optimizes both surface area and manufacturing properties.
3Ease of manufacture
If conventional NCM-based lithium composite transition metal oxide is used, then manufacturing process is simple, but amount of lithium by-product increases
Solution Approach 1:
The patent applies parameter changes by optimizing the sintering temperature (900-1000°C) and time (5-20 hours) parameters to control the formation and removal of lithium by-products. By adjusting these process parameters, the patent reduces lithium by-product formation while maintaining the high-Ni composition and single crystal structure.
4Quantity of substance
If high-Ni NCM-based lithium composite transition metal oxide with large specific surface area is used, then capacity is high, but side reaction with electrolyte solution increases
Solution Approach 1:
The patent applies flexible shells and thin films by coating the high-Ni NCM-based lithium composite transition metal oxide particles with aluminum hydroxide layer. This thin film coating protects the high-capacity Ni-rich material from direct contact with electrolyte, reducing side reactions while preserving the high capacity characteristics of the underlying material.
Solution Approach 2:
The patent uses beforehand cushioning by pre-coating the high-Ni material surface with aluminum hydroxide before battery assembly. This protective layer is applied in advance to cushion and prevent harmful side reactions between the Ni-rich material and electrolyte, reducing gas generation and improving thermal stability before any degradation occurs.
5Productivity
If conventional NCM-based lithium composite transition metal oxide is used, then production efficiency is maintained, but thermal stability deteriorates
Solution Approach 1:
The patent uses composite materials by combining high-Ni NCM-based lithium composite transition metal oxide with aluminum hydroxide coating. This composite structure maintains the production efficiency of Ni-rich material synthesis while adding thermal stability through the aluminum hydroxide component, which acts as a thermal barrier and stabilizer at elevated temperatures.
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 results in a high-Ni NCM-based positive electrode active material with improved particle strength, reduced side reactions, and enhanced thermal stability, minimizing gas generation and ensuring high capacity and stability in lithium secondary batteries.
Implementation Method 1
performing secondary sintering on the mixture at a temperature of 850°C or more to form a lithium composite transition metal oxide composed of a single particle
Implementation Method 2
electrical energy is produced by oxidation and reduction reactions when the lithium ions are intercalated/deintercalated into/from the positive electrode and the negative electrode
Data Source
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AI summary
The present invention relates to a positive electrode active material for a secondary battery which is a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), wherein the lithium composite transition metal oxide includes the nickel (Ni) in an amount of 65 mol% or more and the manganese (Mn) in an amount of 5 mol% or more based on a total amount of transition metals, and at least one particle growth-promoting element selected from the group consisting of strontium (Sr), zirconium (Zr), magnesium (Mg), yttrium (Y), and aluminum (Al), wherein the electrode positive active material is composed of a single particle.