Positive Electrode Active Material Zoning for Capacity and Cycle Stability
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in maintaining high capacity and low resistance change after repeated charge and discharge cycles, which affects their performance and efficiency.
Innovation Solution
A positive electrode active material comprising a lithium nickel-based composite oxide with specific nickel to aluminum ratios in different regions, enhancing structural stability and reducing resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium nickel-based composite oxide with high nickel content is used to achieve high capacity, then the capacity retention and resistance stability after repeated charge and discharge cycles deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high nickel content (Ni ≥ 80 mol%) for high capacity, while the outer shell region contains lower nickel content (Ni < 80 mol%) and includes aluminum (Al ≥ 0.01 mol%) for structural stability. This spatial differentiation of composition allows each region to perform its specific function: the core provides high capacity while the shell maintains structural integrity during cycling, thus resolving the contradiction between high capacity and good capacity retention.
2Quantity of substance
If the nickel content is increased to improve capacity, then the structural stability and resistance change after repeated cycles worsen
Solution Approach 1:
The patent implements local quality by establishing distinct compositional zones: the core region (from center to 0.5-2 μm from outer surface) has high nickel content for capacity, while the shell region (outer 0.5-2 μm layer) has lower nickel content and contains aluminum for structural stability. This local differentiation allows the high-nickel core to deliver high capacity while the aluminum-containing shell maintains structural stability during repeated charge-discharge cycles.
Solution Approach 2:
The patent uses composite materials by combining nickel-rich and aluminum-containing phases in a core-shell architecture. The composite structure integrates the high-capacity nickel-based oxide core with the structurally stable aluminum-containing shell, creating a material that exhibits both high capacity and excellent structural stability during cycling.
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 proposed active material achieves high capacity retention and low resistance change, improving the overall performance and longevity of lithium secondary batteries.
Implementation Method 1
A lithium secondary battery is a battery including a positive electrode and a negative electrode, each including an active material capable of (that is configured for) intercalation and deintercalation of lithium ions
Implementation Method 2
The lithium secondary battery produces electrical energy through the oxidation and reduction reactions if (e.g., when) lithium ions are intercalated into and deintercalated from the positive and negative electrodes during the charging and discharge process
Data Source
AI summary
A positive electrode active material, a positive electrode and a lithium secondary battery containing the same are provided. The positive electrode active material includes a lithium nickel-based composite oxide including nickel (Ni), cobalt (Co) and aluminum (Al), and including a first region, and a second region around (e.g., surrounding) the first region. The second region may be defined as a region having a thickness of about 1 micrometer (μm) in a direction from the outermost to the center of the positive electrode active material. The content (e.g., amount) ratio of nickel to aluminum (NNi/NAl) of the second region may be about 5 to about 45.