Cobalt-Free Cathode Particle Blend for Battery Cycle-Life Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The demand for high-capacity rechargeable lithium batteries is hindered by the scarcity of cobalt, a rare and expensive metal, leading to structural instability and reduced cycle-life performance in cobalt-free positive active materials, particularly those with a layered structure, which face challenges in balancing capacity, efficiency, and long-term cycle-life characteristics.
Innovation Solution
A layered cobalt-free positive active material comprising a composite oxide with a combination of large and small particles, where the second positive active material has a higher nickel concentration, balancing lithium migration rates and structural stability to enhance cycle-life characteristics without compromising capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt-free positive active materials with layered structure are used to achieve high capacity, then capacity and efficiency are improved, but structural stability deteriorates leading to reduced cycle-life
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating aluminum at 0.01-0.10 mol ratio and controlling nickel content at 0.60-0.80 mol ratio in the layered lithium nickel-based composite oxide. This parameter optimization allows achieving high lithium content (x≥0.5 in LixNiyaMn1-yO2) while maintaining structural stability through aluminum's stabilizing effect on the layered structure, thus resolving the contradiction between high capacity and structural stability.
Solution Approach 2:
The patent creates a composite material system by combining nickel, manganese, and aluminum in a specific ratio within the layered lithium nickel-based composite oxide structure. The composite nature of this material allows nickel to provide high capacity while aluminum provides structural stability, and manganese contributes to both capacity and stability, thus achieving simultaneous improvement in capacity, efficiency, and cycle-life characteristics.
2Ease of manufacture
If cobalt is removed from positive active materials to reduce cost and scarcity dependency, then manufacturing cost is reduced, but structural defects increase causing increased resistance and reduced cycle-life
Solution Approach 1:
The patent replaces expensive cobalt with cheaper aluminum and optimized nickel-manganese combinations. Aluminum is abundant and low-cost, and the optimized composite structure provides sufficient structural stability without requiring cobalt, thus achieving cost reduction while maintaining or improving cycle-life through the synergistic composite material design.
Solution Approach 2:
The patent changes the compositional parameters by eliminating cobalt and optimizing the nickel-to-manganese ratio along with aluminum content. This parameter optimization creates a stable layered structure that resists degradation during cycling, achieving long cycle-life without cobalt while reducing manufacturing cost through the use of abundant, low-cost materials.
3Quantity of substance
If nickel content is increased in layered cobalt-free positive active materials to improve capacity, then capacity and efficiency are enhanced, but structural stability decreases leading to increased resistance
Solution Approach 1:
The patent optimizes the nickel content parameter to 0.60-0.80 mol ratio and introduces aluminum at 0.01-0.10 mol ratio. This parameter combination allows high lithium availability (x≥0.5) for high capacity while aluminum compensates for the structural instability that would otherwise result from high nickel content, thus achieving both high capacity and structural stability simultaneously.
Solution Approach 2:
The patent creates a composite material where nickel (providing high capacity through high lithium availability), manganese (providing structural stability and capacity), and aluminum (providing structural stabilization) work synergistically. This composite approach allows high nickel content for capacity while the other elements stabilize the structure, preventing resistance increase.
Data Source
AI summary
A positive active material for rechargeable lithium batteries is provided to include: a first positive active material including a layered cobalt-free lithium nickel-based composite oxide, being in a form of a secondary particle in which a plurality of primary particles are aggregated, and having an average particle diameter of about 8 μm to about 20 μm; and a second positive active material including a layered cobalt-free lithium nickel-based composite oxide, being in a form of a single particle, and having an average particle diameter of about 1 μm to about 7 μm, wherein a molar amount of nickel based on the total molar amount of elements excluding lithium and oxygen in the second positive active material is about 1 mol % to about 10 mol % more than a molar amount of nickel based on the total molar amount of elements excluding lithium and oxygen in the first positive active material.