Positive Electrode Composition for Low-Co Battery Load Performance
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in achieving both low cost and improved load characteristics, particularly when reducing the cobalt content in lithium-transition metal composite oxides used as positive electrode active materials.
Innovation Solution
A non-aqueous electrolyte secondary battery design that incorporates a first positive electrode active material with a particle fracture strength of 90 MPa or less and a second positive electrode active material with a fracture strength of 110 MPa or more, where the first material contains a high nickel and low cobalt content, and the second material has a high nickel and moderate cobalt content, with specific mass ratios and proportions in the positive electrode mixture layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content rate of Co is reduced and the content rate of Ni is increased to greater than or equal to 85 mol % in the lithium-transition metal composite oxide, then the cost is reduced, but the load characteristics are deteriorated
Solution Approach 1:
The positive electrode active material is divided into two distinct types: a first lithium-transition metal composite oxide with high Ni content (≥85 mol %) and low Co content (≤1 mol %) for cost reduction, and a second lithium-transition metal composite oxide with high Ni content (≥85 mol %) and moderate Co content (≥3 mol %) for maintaining load characteristics. This segmentation allows each material type to fulfill specific functional requirements within the composite electrode structure.
Solution Approach 2:
The invention changes the compositional parameters by precisely controlling the Ni and Co content rates in two different lithium-transition metal composite oxides, and further controls the particle fracture strength parameter by adjusting processing conditions. The first material has particle fracture strength ≤90 MPa while the second has particle fracture strength ≥110 MPa, creating a differentiated parameter set that resolves the contradiction between cost and performance.
2Quantity of substance
If the content rate of Ni is increased to greater than or equal to 85 mol % in the lithium-transition metal composite oxide, then the capacity is increased, but the load characteristics are deteriorated
Solution Approach 1:
The positive electrode active material is divided into two distinct types: a first lithium-transition metal composite oxide with high Ni content (≥85 mol %) and low Co content (≤1 mol %) for cost reduction, and a second lithium-transition metal composite oxide with high Ni content (≥85 mol %) and moderate Co content (≥3 mol %) for maintaining load characteristics. This segmentation allows each material type to fulfill specific functional requirements within the composite electrode structure.
Solution Approach 2:
The invention changes the compositional parameters by precisely controlling the Ni and Co content rates in two different lithium-transition metal composite oxides, and further controls the particle fracture strength parameter by adjusting processing conditions. The first material has particle fracture strength ≤90 MPa while the second has particle fracture strength ≥110 MPa, creating a differentiated parameter set that resolves the contradiction between cost and performance.
Data Source
AI summary
A positive electrode mixture layer in this secondary battery contains a first positive electrode active material having a particle fracture strength of 90 MPa or less and a second positive electrode active material having a particle fracture strength of 110 MPa or greater. The first positive electrode active material is a lithium transition metal complex oxide that contains Ni and Mn, and has a Co content ratio of 1 mol % or less. The second positive electrode active material is a lithium transition metal complex oxide that contains Ni and Co, and has a Co content ratio of 3 mol % or greater. Regarding the positive electrode mixture layer, the content of the first positive active material is at least 5 mass % but less than 50 mass % with respect to the combined mass of the first positive electrode active material and the second positive electrode active material.