Positive Electrode Coating Composition for Low-DCR Li-Ion Batteries
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Solution Overview
Problem
Existing lithium-ion batteries for EVTOLs face challenges in balancing high energy density, high power, and long lifespan, necessitating a solution that maintains energy density and cycle-life performance while providing large power output.
Innovation Solution
A positive electrode plate with a coating layer containing a monocrystalline and polycrystalline ternary material, where the mass ratio of monocrystalline ternary material, mass percentage of conductive agent, and areal-density of the coating layer satisfy the formula 0.39 < 10^6 * a * b^2 / c^2 < 2, ensuring optimal energy density, cycle-life performance, and power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the positive electrode plate uses only polycrystalline ternary material to increase power output, then the power performance is improved, but the cycle-life performance deteriorates
Solution Approach 1:
The positive electrode active material comprises a composite of monocrystalline ternary material and polycrystalline ternary material. The monocrystalline component provides stable crystal structure for long cycle life, while the polycrystalline component offers high power output capability. This composite structure resolves the contradiction between power performance and cycle-life performance by combining the advantages of both material types.
Solution Approach 2:
The patent specifies a mass ratio parameter 'a' where 0.05 < a ≤ 0.5, controlling the proportion of monocrystalline to polycrystalline material. By optimizing this parameter, the electrode achieves the best balance between power output and cycle stability, transforming the quality of the electrode composition to simultaneously satisfy both competing requirements.
2Quantity of substance
If the areal-density of the coating layer is increased to improve energy density, then the energy density is improved, but the power performance deteriorates
Solution Approach 1:
The patent establishes a specific relationship between areal-density 'c' and other parameters through the formula 0.39 < 10^6 × a × b²/c² < 2. This parameter optimization ensures that the areal-density is controlled at a level that provides sufficient energy density while maintaining adequate power performance, preventing the deterioration that would occur with excessive areal-density.
Solution Approach 2:
The coating layer is designed with specific local properties including controlled areal-density and conductive agent distribution. The mass percentage of conductive agent 'b' (0.01 < b ≤ 0.05) is optimized to ensure sufficient electrical conductivity at the desired areal-density, allowing high energy density without sacrificing power performance due to conductivity limitations.
3Power
If the mass percentage of conductive agent is increased to improve power performance, then the power performance is improved, but the energy density deteriorates
Solution Approach 1:
The patent optimizes the mass percentage of conductive agent 'b' within the range 0.01 < b ≤ 0.05. This parameter is carefully controlled to provide sufficient electrical conductivity for high power performance while minimizing the amount of non-active material to preserve energy density. The relationship between 'b' and other parameters in the formula 0.39 < 10^6 × a × b²/c² < 2 further refines this optimization.
Data Source
AI summary
The present disclosure provides a positive electrode, including a positive electrode current collector and a coating layer coated on at least one surface of the positive electrode current collector perpendicular to a thickness direction. The coating layer includes a positive electrode active material and a conductive agent, and the positive electrode active material includes a monocrystalline ternary material and a polycrystalline ternary material. The coating layer satisfies Formula I: 0.39<106ab2/c2<2; where in Formula I, a is a mass ratio of the monocrystalline ternary material in the positive electrode active material, b is a mass percentage content of the conductive agent in the coating layer, and c is an areal-density of the coating layer in mg/cm2. In the present disclosure, when the positive electrode satisfies the Formula I, the lithium-ion battery prepared by the positive electrode could achieve an excellent DCR performance while ensuring energy density and cycle-life performance simultaneously.