Positive Electrode Material Sintering for High-Density Li-Ion Cathodes
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Solution Overview
Problem
Lithium nickel cobalt metal oxides face limitations in capacity and thermal stability, and increasing nickel content leads to lithium by-products that cause swelling and degrade battery performance.
Innovation Solution
A method of preparing a positive electrode material by mixing two kinds of positive electrode active materials with different average particle diameters, optimizing the equivalence ratio of lithium compounds, and performing pre-sintering and main-sintering to enhance packing density and sintering uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of nickel in lithium nickel cobalt metal oxide is increased to achieve high capacity, then reversible capacity is improved, but lithium by-products (LiOH and Li2CO3) are generated on the surface causing swelling and degraded battery performance
Solution Approach 1:
The patent extracts and removes lithium by-products (LiOH and Li2CO3) from the surface of the positive electrode active material through a washing process using water or alcohol, preventing the harmful effects of these by-products while preserving the high nickel content structure for maintaining high capacity
Solution Approach 2:
The patent optimizes the washing conditions including washing temperature (20-40°C), washing time (1-12 hours), and washing solution volume (1-5 times the material volume) to effectively remove lithium by-products while preventing material degradation and maintaining high capacity characteristics
2Quantity of substance
If positive electrode active material is rolled to increase packing density for high energy density, then energy density is improved, but the positive electrode active material is damaged and life characteristics are significantly degraded
Solution Approach 1:
The patent performs preliminary actions including optimizing particle size distribution (D10-D90 range of 3-30 μm), surface treatment, and controlled drying before electrode fabrication to prevent material damage during subsequent rolling processes while achieving high packing density and maintaining excellent life characteristics
3Quantity of substance
If lithium nickel cobalt metal oxide is used to achieve high reversible capacity, then capacity is improved, but thermal stability is poorer compared to LiCoO2
Solution Approach 1:
The patent uses composite lithium nickel cobalt metal oxide with specific composition ratios (Ni: 0.8-0.95, Co: 0.02-0.1, Mn: 0.02-0.1) combining multiple metal elements to achieve both high reversible capacity and improved thermal stability, leveraging the complementary properties of each metal element
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 improves capacity and resistance characteristics by increasing packing density and ensuring uniform sintering, reducing lithium by-products, and enhancing electrochemical properties.
Implementation Method 1
performing pre-sintering and main-sintering to enhance packing density and sintering uniformity
Data Source
AI summary
A method of preparing a positive electrode material is provided. The method includes mixing a first positive electrode active material precursor having an average particle diameter (D50) of 10 μm to 30 μm with a lithium-containing raw material and pre-sintering the mixture to obtain a first pre-sintered product, mixing a second positive electrode active material precursor having an average particle diameter (D50) different from that of the first positive electrode active material precursor with a lithium-containing raw material and pre-sintering the mixture to obtain a second pre-sintered product, disintegrating each of the first pre-sintered product and the second pre-sintered product, and mixing the disintegrated first pre-sintered product and the disintegrated second pre-sintered product and main-sintering the mixture to obtain a positive electrode material.