Layered-Spinel Composite Electrode Active Material for Battery Rate and Density
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Solution Overview
Problem
Conventional electrode active materials for non-aqueous secondary batteries, such as lithium secondary batteries, face challenges in achieving a balance between rate characteristics and energy density, particularly in applications requiring high performance like automobiles.
Innovation Solution
The development of an electrode active material comprising a lithium mixed metal oxide with a layered rock-salt type crystal structure and a spinel type crystal structure, specifically formulated to optimize BET specific surface area, particle size, and composition, enhancing both rate characteristics and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the BET specific surface area of the layered rock-salt type crystal structure powder is increased to improve rate characteristics, then the energy density decreases due to increased void volume and reduced filling density
Solution Approach 1:
The invention optimizes the BET specific surface area parameter of the layered rock-salt type crystal structure powder to a specific range (3-30 m2/g). This parameter change resolves the contradiction by finding the optimal value that balances rate characteristics (improved by higher surface area) and energy density (maintained by avoiding excessive surface area that would increase void volume).
Solution Approach 2:
The invention uses a composite material system combining layered rock-salt type crystal structure powder with spinel type crystal structure powder. The spinel component complements the layered structure, providing a synergistic effect that improves rate characteristics without sacrificing energy density, as the spinel phase has different properties that compensate for the voids created by high-surface-area layered particles.
2Speed
If the particle size of the layered rock-salt type crystal structure powder is reduced to improve rate characteristics, then the manufacturing complexity and aggregation control difficulty increase
Solution Approach 1:
The invention specifies a controlled particle size range for primary particles (0.01-0.5 μm) and aggregated particles (0.05-2 μm average diameter). This parameter optimization resolves the contradiction by selecting a size range small enough to improve rate characteristics but large enough to avoid excessive aggregation and manufacturing complexity. The defined ranges provide clear manufacturing targets.
Solution Approach 2:
The invention describes a segmented particle structure where small primary particles (0.01-0.5 μm) aggregate to form larger particles (0.05-2 μm average diameter). This segmentation resolves the contradiction by allowing the small primary particles to provide high rate characteristics while the controlled aggregation into larger particles reduces manufacturing complexity and prevents excessive fine particle handling issues.
3Quantity of substance
If the nickel content in the layered rock-salt type crystal structure is increased to improve energy density, then the structural stability and cycle life deteriorate
Solution Approach 1:
The invention uses different metal compositions in different crystal structure phases. The layered rock-salt type phase contains high nickel content (x+y > 0) for energy density, while the spinel type phase contains Mn and other stabilizing elements (Al, Mg, transition metals) for structural stability. This local quality differentiation resolves the contradiction by assigning different functional roles to different phases.
Solution Approach 2:
The invention creates a composite material where layered rock-salt type Li(Ni1-(x+y)MnxFey)O2 is combined with spinel type Li(MnaM1-a)2O4. The high-nickel layered phase provides energy density while the spinel phase with Mn and stabilizing metals provides structural stability. The composite structure allows both high nickel content and good stability to coexist.
Data Source
AI summary
The present invention provides an electrode active material, an electrode and a non-aqueous electrolyte secondary battery. The electrode active material contains the following powder (A) and powder (B):(A) a powder of a lithium mixed metal oxide that is represented by the following formula (1) and has a layered rock-salt type crystal structure, the powder having a BET specific surface area of from 3 m2/g to 30 m2/g,Li(Ni1−(x+y)MnxFey)O2 (1)wherein x is within a range of more than 0 to less than 1, y is within a range of more than 0 to not more than 0.1, and x+y is within a range of more than 0 to less than 1;(B) a powder of a lithium mixed metal oxide that has a spinel type crystal structure.The electrode contains the electrode active material. The non-aqueous electrolyte secondary battery includes the electrode as a positive electrode.