Bimodal Nickel-Rich Cathode Material for Battery Cycle Life
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Solution Overview
Problem
Lithium cobalt-based oxides, commonly used in rechargeable lithium batteries, face challenges due to high manufacturing costs and scarcity of cobalt resources, while lithium nickel-based composite oxides offer high capacity but suffer from synthesis difficulties and poor cycle-life characteristics.
Innovation Solution
A bimodal positive electrode active material comprising large and small lithium nickel-based composite oxides, prepared using different reactors, is designed to minimize cobalt content, ensuring a weight ratio and particle size distribution that enhances energy density and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt-based oxides are used as positive electrode active materials, then high energy density is achieved, but manufacturing cost increases and resource stability deteriorates
Solution Approach 1:
The patent changes the compositional parameters by reducing cobalt content from conventional levels to 0.1-5 mol% while increasing nickel content to 70-95 mol%, and adjusts particle size parameters by creating a bimodal distribution with small particles (3-10 μm) and large particles (10-20 μm). This parameter optimization achieves high energy density while reducing manufacturing cost and resource dependency
Solution Approach 2:
The patent creates a composite positive electrode active material combining lithium nickel-based composite oxide with high nickel content and controlled bimodal particle size distribution. This composite structure integrates the advantages of high capacity from nickel-rich composition with improved structural stability from particle size optimization, achieving both high energy density and cost-effectiveness
2Ease of manufacture
If lithium nickel-based composite oxides are used to reduce cost, then manufacturing cost decreases, but cycle-life characteristics worsen
Solution Approach 1:
The patent optimizes the nickel content parameter to 70-95 mol% (balanced rather than maximum) and controls cobalt content at 0.1-5 mol% for structural stability. The particle size parameters are precisely controlled with a bimodal distribution (small: 3-10 μm, large: 10-20 μm), which improves structural stability during cycling and enhances cycle-life characteristics while maintaining cost-effectiveness
Solution Approach 2:
The patent applies different particle size qualities to different functional requirements: small particles (3-10 μm) provide high surface area for good initial capacity and reaction kinetics, while large particles (10-20 μm) provide structural stability and resistance to cracking during cycling. This local quality differentiation resolves the cycle-life issue
3Use of energy by moving object
If high nickel content is used to achieve high capacity, then energy density improves, but synthesis difficulty increases
Solution Approach 1:
The patent sets nickel content at 70-95 mol% (optimized range rather than extreme maximum) and controls cobalt at 0.1-5 mol% for synthesis feasibility. The particle size parameters (bimodal distribution with small: 3-10 μm, large: 10-20 μm) are controlled to achieve uniform synthesis. These parameter optimizations enable high energy density while maintaining reasonable synthesis difficulty through improved powder formability
Data Source
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AI summary
Disclosed are a positive electrode active material for a rechargeable lithium battery, a positive electrode, and a rechargeable lithium battery, the positive electrode active material for a rechargeable lithium battery including large particles including a first lithium nickel-based composite oxide and small particles including a second lithium nickel-based composite oxide, wherein a nickel content based on 100 mol% of a total metal excluding lithium is greater than or equal to about 80 mol%, a ratio (A/B) of a weight (A) of the first lithium nickel-based composite oxide and a weight (B) of the second lithium nickel-based composite oxide in the positive electrode active material is about 1 to about 4, a span of the first lithium nickel-based composite oxide is about 0.9 to about 1.2, a span of the second lithium nickel-based composite oxide is about 0.9 to about 1.2, and a span of the positive electrode active material is about 1.5 to about 2.