Layered Lithium Composite Oxide Particles for Battery Capacity and Output
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face limitations in increasing capacity and output due to the trade-off relationship between particle density and electrolyte access, leading to suboptimal performance in existing lithium composite oxide positive electrode materials.
Innovation Solution
A positive electrode active material with a layered structure lithium composite oxide, specifically nickel cobalt manganese composite oxide, is developed, with a tap density of 2.8 to 3.0 g/cm3 and a dibutyl phthalate absorption value of 14.5 to 18.5 mL/100 g, allowing for increased capacity and output while minimizing side reactions and capacity degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If particle density of lithium composite oxide is increased to increase capacity, then capacity of battery is improved, but electrolyte access to particles is reduced, causing output to deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior core region has high density for capacity while the exterior shell region has optimized surface properties for electrolyte access. This is achieved through controlled particle formation processes that create radial gradients in composition and structure, allowing different regions of the same particle to serve different functions - the core provides lithium storage capacity while the shell facilitates ion transport.
Solution Approach 2:
The patent implements nesting by creating hierarchical particle structures where primary particles are nested within secondary particle aggregates. This multi-level nesting allows the inner primary particles to maintain high density for capacity while the outer aggregate structure creates interconnected pathways for electrolyte penetration, effectively nesting high-density regions within a transport-friendly matrix.
2Quantity of substance
If particle density is increased to improve capacity, then energy density is improved, but surface area to volume ratio decreases, causing electrolyte contact to worsen
Solution Approach 1:
The patent applies segmentation by dividing the particle structure into multiple discrete primary particles that aggregate to form secondary particles. This segmentation creates a hierarchical architecture where the total surface area is distributed across many small primary particle surfaces, maintaining high surface area to volume ratio even as the overall particle size and density increase for higher capacity.
3Quantity of substance
If nickel content is increased to increase capacity, then battery capacity is improved, but initial resistance increases, causing output to deteriorate
Solution Approach 1:
The patent implements composite materials by creating a multi-component lithium composite oxide with specific ratios of nickel, cobalt, and manganese elements. This composite approach allows nickel to provide high capacity while cobalt and manganese contribute to structural stability and electrical conductivity, respectively. The synergistic combination balances capacity and resistance properties that cannot be achieved with single-element oxides.
Data Source
AI summary
Provided is a positive electrode active material capable of increasing capacity and output of a nonaqueous electrolyte secondary battery. A positive electrode active material disclosed here includes particles of a lithium composite oxide having a layered structure. The positive electrode active material has a tap density of 2.8 g/cm3 to 3.0 g/cm3, and the positive electrode active material has a dibutyl phthalate absorption value of 14.5 mL/100 g to 18.5 mL/100 g.