Positive Active Material Composition for Li-Ion Energy Density and Life
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Solution Overview
Problem
Lithium-ion batteries face a trade-off between increased energy density and reduced service life, necessitating a solution that enhances energy density without compromising battery longevity.
Innovation Solution
A positive active material comprising a first particle with a smaller diameter and a second particle with a larger diameter, both doped with specific elements like Ni, Mn, Al, Mg, Ti, La, and Zr, to improve discharge capacity retention and thermal stability, while maintaining a balanced content of these elements to optimize energy density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the energy density of the lithium-ion battery is increased, then the energy density is improved, but the service life of the lithium-ion battery is decreased
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the first particle (core) and second particle (shell) have different compositions and functions. The first particle Li1-eCoxM1-gO2-i provides high capacity, while the second particle Li1-fCohN1-hO2-j provides stability and protection. This local differentiation allows the battery to achieve high energy density from the core while maintaining service life through the protective shell structure.
Solution Approach 2:
The patent employs composite materials by combining two different lithium-containing compounds with distinct properties. The first compound (Li1-eCoxM1-gO2-i) where M includes at least two of Ni, Mn, Al, Mg, Ti, La, Y, Zr provides high energy density, while the second compound (Li1-fCohN1-hO2-j) where N includes at least one of the same elements provides structural stability. This composite approach resolves the contradiction between energy density and service life by integrating the advantages of both materials.
2Area of stationary object
If the particle diameter of the first particle is reduced to increase surface area, then the reactivity is improved, but the stability of the particle is decreased
Solution Approach 1:
The patent applies beforehand cushioning by using the second particle (Li1-fCohN1-hO2-j) as a protective shell that surrounds and stabilizes the first particle (Li1-eCoxM1-gO2-i). This outer shell is specifically designed to prevent structural degradation of the inner core particle, providing preemptive protection against instability that would otherwise occur due to the small size and high surface area of the first particle.
Solution Approach 2:
The patent applies local quality by assigning different functional characteristics to different regions of the composite particle. The inner first particle is optimized for high reactivity and surface area, while the outer second particle is optimized for structural stability and protection. This spatial differentiation of properties allows the system to simultaneously achieve high reactivity from the inner core and high stability from the outer shell.
Data Source
AI summary
A positive active material including a first particle and a second particle. The first particle has a chemical formula of LieCog M1-gO2-i, and the second particle has a chemical formula of LifCohN1-hO2-j. M is at least two selected from the group of Ni, Mn, Al, Mg, Ti, La, Y and Zr. N is at least one selected from a group of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8≤e≤1.2, 0<g<1, −0.1≤i≤0.2, 0.85≤f≤1.2, 0<h<1, −0.1≤j≤0.2, the number of types of the element M in the first particle is greater than the number of types of the element N in the second particles, the particle diameter of the positive active material meets the following formula (3):(Dv90-Dv50)−(Dv50-Dv10)≤2.5.