High-Nickel Lithium-Ion Electrode Composition for Low Resistance
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Solution Overview
Problem
The increasing demand for lithium ion secondary batteries for vehicles has led to concerns about cobalt depletion, and reducing cobalt content in positive electrode active materials results in significant increases in initial resistance and storage time resistance.
Innovation Solution
A lithium ion secondary battery design featuring a positive electrode with a lithium-transition metal complex oxide having a high nickel content (>75 mol%) and a layered structure, combined with a negative electrode containing carbon and silicon materials, to decrease cobalt content while maintaining low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the containing rate of Co in the positive electrode active material is decreased, then cobalt depletion is addressed and cost is reduced, but initial resistance increases significantly and resistance at storing time increases
Solution Approach 1:
The patent changes the compositional parameters of the positive electrode active material by specifying a Ni-containing rate of 75-95 mol% and Co-containing rate of 0-10 mol%, along with specific aspect ratio parameters (1.9-2.5) for primary particles. These parameter changes enable high nickel content while controlling resistance through precise compositional and morphological control
Solution Approach 2:
The patent uses a composite lithium-transition metal complex oxide material combining Li, Ni, and Mn elements in specific ratios. This composite material approach allows leveraging nickel's high capacity while manganese provides structural stability, achieving low resistance without relying on cobalt
2Quantity of substance
If the containing rate of Ni in the lithium-transition metal complex oxide is increased to >75 mol%, then cobalt content is decreased, but the structural stability and resistance control become more difficult
Solution Approach 1:
The patent specifies precise parameter ranges: Ni-containing rate of 75-95 mol%, Co-containing rate of 0-10 mol%, Mn-containing rate of 5-20 mol%, and aspect ratio of 1.9-2.5. These controlled parameters ensure that high nickel content maintains structural stability through optimized compositional balance and particle morphology
Solution Approach 2:
The patent applies local quality by controlling the distribution and arrangement of metal elements within the complex oxide structure, and by specifying aspect ratio characteristics of primary particles. This localized control of material properties ensures structural stability in specific regions while maintaining overall high nickel content
Data Source
AI summary
A positive electrode comprises a positive electrode active material layer that contains a positive electrode active material. The positive electrode active material contains a lithium-transition metal complex oxide having a layered structure in which a Ni containing rate with respect to metal elements other than Li containing Li, Ni, and Mn is equal to or more than 75 mol %. The lithium-transition metal complex oxide is a secondary particle in which primary particles whose aspect ratios are equal to or more than 1.9 are aggregated. A negative electrode comprises a negative electrode active material layer that contains a negative electrode active material. The negative electrode active material contains a carbon material and a Si containing material, and a Si element containing ratio is equal to or more than 5 mass % and not more than 10 mass % when a total amount of the negative electrode active material is treated as 100 mass %.