Al-W Coated Cathode Active Material for High-Nickel Battery Lifespan
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
NMC-based lithium composite transition metal oxides in the form of single particles exhibit high lithium diffusion resistance, non-uniform lithium-ion movement, and structural instability at high voltages and temperatures, leading to rapid performance degradation.
Innovation Solution
A positive electrode active material comprising lithium composite transition metal oxide in the form of a single particle or pseudo-single particle, coated with aluminum and tungsten, and controlled nickel content and BET specific surface area to enhance stability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If NMC-based lithium composite transition metal oxide is used in the form of a single particle, then particle strength is improved and particle breakage is reduced, but lithium diffusion resistance increases and lifespan properties deteriorate
Solution Approach 1:
The invention divides the single particle structure into multiple fine particles (secondary particles) that are aggregated together. Each fine particle maintains its own diffusion pathways while the aggregated structure provides enhanced mechanical strength. This segmentation resolves the contradiction by allowing lithium ions to diffuse efficiently through multiple smaller particles rather than one large particle, while the aggregated structure prevents breakage during manufacturing and cycling.
Solution Approach 2:
The invention creates a composite structure where multiple fine particles are aggregated to form secondary particles with controlled morphology. This composite approach combines the advantages of small particles (low diffusion resistance) with the benefits of larger aggregated structures (high mechanical strength and reduced breakage). The specific aggregation pattern and particle size distribution are optimized to balance diffusion pathways with structural integrity.
2Quantity of substance
If the nickel content is increased to improve capacity, then capacity properties are improved, but structural stability deteriorates and lifespan properties decrease
Solution Approach 1:
The invention applies local quality by creating a core-shell structure where the core region has high nickel content for capacity while the shell or surface regions have modified composition for stability. The fine particle aggregation also creates local variations in stress distribution during lithium insertion/extraction, with individual particles experiencing localized strain that is distributed across the aggregate, preventing catastrophic structural failure.
Solution Approach 2:
The invention changes physical parameters including particle size distribution, aggregation morphology, and surface area-to-volume ratio. By controlling these parameters, the material achieves high capacity through optimized nickel content while maintaining stability through controlled particle architecture. The specific surface area and pore structure are tuned to accommodate volume changes during cycling, preventing structural degradation.
3Speed
If the BET specific surface area is increased to improve lithium mobility, then lithium diffusion is enhanced, but side reactions with electrolyte increase and lifespan properties deteriorate
Solution Approach 1:
The invention utilizes a porous aggregated structure where the secondary particles contain internal porosity and interconnected pathways. This porous architecture provides extensive surface area for lithium diffusion while the porous network allows efficient ion transport through the particle aggregate. The controlled porosity ensures that high surface area does not directly translate to high electrolyte contact, as the internal surfaces are accessible primarily to lithium ions rather than bulk electrolyte.
Solution Approach 2:
The aggregated particle structure acts as an intermediary between the high-surface-area fine particles and the electrolyte. The aggregation creates a hierarchical structure where the outer surface of the secondary particle aggregate has limited electrolyte contact, while internal pores provide diffusion pathways for lithium ions. This intermediary structure mediates between the need for high surface area (for mobility) and the need to minimize harmful electrolyte reactions.
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 coating layer with aluminum and tungsten improves high-voltage and high-temperature lifespan properties by reducing particle breakage and side reactions, maintaining structural integrity and lithium mobility.
Implementation Method 1
a coating layer which contains aluminum (Al) and tungsten (W)
Implementation Method 2
the positive electrode and the negative electrode include active materials capable of intercalation and de-intercalation of lithium ions
Implementation Method 3
the coating layer with aluminum and tungsten improves high-voltage and high-temperature lifespan properties by reducing particle breakage
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A positive electrode active material includes a lithium composite transition metal oxide in the form of a single particle composed of one single nodule and/or in the form of a pseudo-single particle, which is a composite of 30 or less nodules, and a coating layer formed on the surface of the lithium composite transition metal oxide. The coating layer contains aluminum (Al) and tungsten (W). The positive electrode active material satisfies Equation 1 below: 45≤X×X′≤56 wherein, X is the content of nickel among all metals except for lithium in the lithium composite transition metal oxide(unit: mol%), and X' is the BET specific surface area of the positive electrode active material (unit: m2/g).