Lithium-Molybdenum Coated Cathode Particles for Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with non-uniform chemical structure and structural deformation in lithium-transition metal composite oxides, leading to capacity and life-span deterioration due to lithium precipitation and inadequate removal of impurities, which affects operational stability and electrochemical properties.
Innovation Solution
A cathode active material is developed using lithium-transition metal composite oxide particles with a hexagonal close-packed structure, incorporating a lithium-molybdenum-containing portion formed between primary particles, which is achieved through a method involving a molybdenum compound aqueous solution and heat-treatment without water-washing, enhancing structural integrity and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If water washing is used to remove lithium salt impurities, then impurity removal is attempted, but impurities are not sufficiently removed and particle surface damages are caused
Solution Approach 1:
The patent changes the washing parameter from water to organic solvent (acetonitrile, ethyl acetate, or a mixture), which fundamentally alters the interaction between the washing medium and the particle surface. This parameter change enables effective impurity removal while preventing particle surface damage that occurs with water washing
Solution Approach 2:
The patent uses organic solvents as a disposable washing medium that can be easily removed after washing. The solvent serves its purpose of removing impurities and then is discarded, leaving no residual damage to the particle surface unlike water which causes structural damage
2Quantity of substance
If lithium-transition metal composite oxide is used for high capacity, then capacity is improved, but non-uniformity in chemical structure occurs due to lithium precipitation
Solution Approach 1:
The patent applies local quality by forming a coating layer on the surface of the cathode active material particles. This coating has different composition and properties from the bulk material, creating a localized region that prevents lithium precipitation at the particle surface while maintaining the high-capacity bulk composition
Solution Approach 2:
The patent creates a composite structure by combining the lithium-transition metal composite oxide with a coating material formed from the organic solvent treatment. This composite structure integrates the high-capacity core material with a protective surface layer that maintains chemical structure uniformity
3Duration of action of stationary object
If repeated charging and discharging is performed to extend life-span, then usage duration is improved, but structural deformation or damages occur
Solution Approach 1:
The patent applies beforehand cushioning by forming a protective coating layer on the particle surface before the battery undergoes repeated charging and discharging. This pre-formed coating acts as a cushion that absorbs mechanical stress and prevents structural deformation during cyclic operation
Solution Approach 2:
The patent changes the surface properties of the particles through organic solvent treatment, creating a surface layer with different mechanical and chemical properties. This parameter change enhances the particle's resistance to structural deformation during repeated charging and discharging cycles
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 improves the operational stability and electrochemical properties of lithium secondary batteries by protecting primary particle surfaces, reducing resistance at particle interfaces, and maintaining capacity and life-span retention during repeated charging and discharging.
Implementation Method 1
which is achieved through a method involving a molybdenum compound aqueous solution and heat-treatment
Implementation Method 2
a lithium-molybdenum-containing portion having a hexagonal close-packed structure formed between the primary particles
Implementation Method 3
protecting primary particle surfaces, reducing resistance at particle interfaces
Implementation Method 4
reducing resistance at particle interfaces, and maintaining capacity and life-span retention
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A cathode active material for a lithium secondary battery according to an embodiment of the present invention includes a plurality of a lithium-transition metal composite oxide particle having a shape of a secondary particle in which a plurality of primary particles are aggregated. The lithium-transition metal composite oxide particle includes a lithium-molybdenum-containing portion having a hexagonal close-packed structure formed between the primary particles.