Composite Cathode Active Material for Dense, Stable Li-Ion Electrodes
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Solution Overview
Problem
Current lithium secondary batteries face challenges in achieving high energy density, stability at high temperatures, and cost-effectiveness due to issues with nickel-based and cobalt-based active materials, including low mixture density, high manufacturing costs, and brittleness.
Innovation Solution
A positive electrode active material comprising a combination of lithium cobalt-based and lithium nickel cobalt-based materials, where the lithium cobalt-based material has a larger particle diameter and content, and the lithium nickel cobalt-based material is a one-body active material with a smaller particle diameter, enhancing mixture density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based active material is utilized, then high intrinsic capacity is achieved, but mixture density becomes difficult to achieve due to large average particle diameter and hard spherical shape
Solution Approach 1:
The positive electrode active material is divided into two distinct components: lithium cobalt-based particles (first active material) and lithium nickel cobalt-based particles (second active material). Each component serves a specific function - the lithium cobalt-based material provides structural stability and density, while the lithium nickel cobalt-based material contributes high capacity. This segmentation allows optimization of each component's properties independently, resolving the contradiction between capacity and mixture density.
Solution Approach 2:
The patent creates a composite positive electrode active material by combining lithium cobalt-based oxide particles with lithium nickel cobalt-based oxide particles in specific weight ratios (7:3 to 3:7). The composite structure leverages the advantages of both materials: the lithium cobalt-based component provides high mixture density and stability, while the lithium nickel cobalt-based component adds intrinsic capacity. This composite approach enables simultaneous achievement of high capacity and suitable mixture density that cannot be obtained with single-material systems.
2Quantity of substance
If cobalt-based positive electrode active material is used, then high capacity is achieved, but manufacturing cost increases
Solution Approach 1:
The patent modifies the compositional parameters of the positive electrode active material by controlling the weight ratio of lithium cobalt-based oxide to lithium nickel cobalt-based oxide. By adjusting this ratio within the range of 7:3 to 3:7, the manufacturing cost can be optimized while maintaining high capacity. The lithium nickel cobalt-based material, which has lower cost than pure cobalt-based materials, is incorporated in significant amounts (30-70 wt%), thereby reducing overall manufacturing cost while preserving high capacity characteristics.
3Use of energy by moving object
If high-capacity, high-temperature, and high-voltage conditions are pursued, then energy density improves, but stability deteriorates
Solution Approach 1:
The lithium cobalt-based oxide particles act as an intermediary or stabilizing component in the composite structure. These particles provide structural stability and thermal stability under high-temperature and high-voltage conditions, while the lithium nickel cobalt-based oxide particles contribute to high capacity. The combination creates a synergistic effect where the stable lithium cobalt-based component protects the high-capacity lithium nickel cobalt-based component, enabling the electrode to maintain stability while achieving high energy density under extreme operating conditions.
Data Source
AI summary
A lithium secondary battery includes a positive electrode including a positive electrode active material, a negative electrode, and an electrolyte located therebetween. The positive electrode active material includes a lithium cobalt-based active material and a lithium nickel cobalt-based active material, wherein the lithium cobalt-based active material is larger in size and amount than the lithium nickel cobalt-based active material, and the lithium nickel cobalt-based active material is a one-body positive electrode active material.