High-Nickel Positive Electrode Material with Two-Step Firing
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Solution Overview
Problem
High nickel content positive electrode active materials in lithium secondary batteries suffer from rapid electrochemical performance deterioration during charging and discharging, leading to reduced lifespan and capacity retention.
Innovation Solution
A method involving the mixing of a high nickel content positive electrode active material precursor with a lithium-containing raw material, followed by primary and secondary firing, and the addition of a nickel compound with a specific nickel mol percentage, to produce a lithium transition metal oxide with improved initial capacity and lifespan properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content is increased to 80 mol % or greater to increase energy density, then charging and discharging capacity are increased, but lifespan properties (capacity retention rate and gas generation amount) are rapidly deteriorated
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior maintains high nickel content (80 mol % or greater) for high capacity, while the exterior surface is coated with a protective layer containing nickel compound (0.01-0.15 mol %) that prevents degradation. This allows different regions of the same material to have different compositions optimized for their specific functions.
Solution Approach 2:
The patent uses composite materials by combining high-nickel lithium transition metal oxide with nickel compound to form a composite structure. The composite consists of a core material (high nickel content for capacity) and a coating material (nickel compound for protection), achieving both high energy density and improved lifespan properties.
2Quantity of substance
If the nickel content is increased to increase energy density, then initial capacity is improved, but charge transfer resistance increases rapidly
Solution Approach 1:
The protective coating layer with controlled nickel compound content (0.01-0.15 mol %) is applied locally on the surface to reduce charge transfer resistance, while the bulk material maintains high nickel content for high initial capacity. This localized modification solves the surface resistance issue without compromising the overall capacity.
Solution Approach 2:
The patent changes the nickel compound content parameter in the coating layer to optimize charge transfer resistance. By controlling the nickel compound content within a specific range (0.01-0.15 mol %), the surface properties are modified to reduce resistance while maintaining the high-capacity bulk composition.
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 method enhances both initial capacity and lifespan properties of lithium secondary batteries by optimizing the nickel content and firing temperatures, reducing charge transfer resistance and maintaining performance over cycles.
Implementation Method 1
performing primary firing on the mixture to prepare a primary fired product, and (B) mixing the primary fired product and a nickel compound, and then performing secondary firing on the mixture
Data Source
AI summary
present disclosure A method for preparing a positive electrode active material capable of implementing a battery excellent in both initial capacity and lifespan properties includes (A) mixing a positive electrode active material precursor containing 80 mol % or greater of nickel (Ni) in all metals with a lithium-containing raw material, and then performing primary firing on the mixture to prepare a primary fired product, and (B) mixing the primary fired product and a nickel compound, and then performing secondary firing on the mixture to prepare a lithium transition metal oxide. The nickel compound is added such that the mol % of nickel contained in the nickel compound is greater than 0.01 mol % to less than 0.15 mol % based on the total number of moles of the metals contained in the positive electrode active material precursor.