Cathode Active Material Coatings for Low-Cobalt Battery Stability
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Solution Overview
Problem
The demand for high-capacity, high-energy-density rechargeable lithium batteries has increased, but the supply of cobalt, a rare and expensive metal, is limited, necessitating the development of positive electrode active materials that either exclude or significantly reduce cobalt content while maintaining high capacity and structural stability, especially in layered lithium nickel-manganese-based materials.
Innovation Solution
A positive electrode active material is developed with a lithium nickel-manganese-based composite oxide core coated with an aluminum layer and a cobalt-containing grain boundary coating, enhancing structural stability and reducing gas generation under high-voltage and high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cobalt is used in positive electrode active materials to achieve high capacity and energy density, then battery performance is improved, but material cost increases and resource availability decreases
Solution Approach 1:
The patent removes cobalt from the positive electrode active material composition, extracting this expensive and scarce metal from the system while maintaining battery performance through alternative lithium nickel-manganese-based compositions
Solution Approach 2:
The patent replaces expensive cobalt with more abundant and cost-effective lithium nickel-manganese-based materials, using cheaper substitutes to achieve the same functional goals without relying on scarce resources
2Quantity of substance
If cobalt is reduced or eliminated from positive electrode active materials, then material cost decreases and resource availability improves, but structural stability and capacity may deteriorate
Solution Approach 1:
The patent applies different compositional qualities to different regions: the core uses lithium nickel-manganese-based composite oxide for stability, while the grain boundaries contain cobalt specifically where it is needed for structural reinforcement, creating localized functional zones
Solution Approach 2:
The patent creates a composite structure combining lithium nickel-manganese-based composite oxide with cobalt-containing grain boundary phases, merging the stability benefits of cobalt-free materials with the structural support of cobalt at critical interfaces
3Use of energy by moving object
If high-nickel content materials are used to achieve high capacity, then energy density improves, but material stability and cycle life worsen
Solution Approach 1:
The patent creates compositional gradients where the core region has high nickel content for capacity while the grain boundaries have different composition for stability, allowing each region to optimize its local function
Solution Approach 2:
The patent forms a composite structure with lithium nickel-manganese-based composite oxide in the core and cobalt-containing phases at grain boundaries, combining high-capacity materials with stability-providing materials in a synergistic configuration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The material achieves high density, high capacity, and long cycle-life characteristics while minimizing gas production during high-temperature storage, thereby improving the performance and safety of rechargeable lithium batteries.
Implementation Method 1
a grain boundary coating portion that is located on a surface of the primary particles and includes cobalt
Data Source
AI summary
A positive electrode active material for rechargeable lithium batteries includes core particles including a layered lithium nickel-manganese-based composite oxide and being in a form of secondary particles, wherein the secondary particles are each an agglomeration of a plurality of primary particles; an aluminum coating layer on a surface of the core particles; and a grain boundary coating portion being located on the surface of the primary particles and including cobalt. The positive electrode active material may realize characteristics of high density, high capacity, and long cycle-life for the rechargeable lithium batteries including the positive electrode active material, and reduce an amount of high-temperature storage gas generated.