Ni-Rich Positive Electrode Material with Al-Tuned Surface Layer
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in maintaining high capacity and capacity retention with minimal resistance change after repeated charge and discharge cycles.
Innovation Solution
A positive electrode active material comprising a lithium nickel-based composite oxide with specific nickel to aluminium ratios in different regions, enhancing structural stability and reducing surface reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium nickel-based composite oxide with high nickel content is used to increase capacity, then the capacity increases, but the resistance change and capacity retention deteriorate after repeated charge and discharge
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 (thickness 0.1-10 μm) has controlled nickel content (5-45 mol% Ni/Al ratio) for stability. This spatial differentiation of composition allows simultaneous achievement of high capacity and good capacity retention by assigning different functional properties to different regions of the same material particle.
2Quantity of substance
If a lithium nickel-based composite oxide with high nickel content is used to increase capacity, then the capacity increases, but the resistance change after repeated charge and discharge increases
Solution Approach 1:
The patent employs composite materials by combining nickel-rich core material with an aluminum-containing shell material to form a composite oxide structure. The core provides high capacity through nickel's electrochemical activity, while the aluminum-containing shell reduces resistance change by providing structural stability and reducing side reactions. This composite approach allows the material to exhibit properties superior to either component alone.
3Reliability
If the positive electrode active material is designed with regional composition differences, then capacity retention improves, but the manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the positive electrode active material into distinct compositional regions: a central core region with high nickel content and an outer shell region with controlled nickel-aluminum ratio. This segmentation enables independent optimization of each region's composition for its specific function, while the clear spatial boundaries facilitate controlled synthesis through sequential coating or gradient formation processes during manufacturing.
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 solution provides a positive electrode active material with high capacity retention and low resistance change, improving the performance and longevity of lithium secondary batteries.
Implementation Method 1
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 oxidation and reduction reactions if (e.g., when) lithium ions are intercalated into, and deintercalated from, the positive and negative electrodes during a charging and discharge process
Data Source
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AI summary
A positive electrode active material, and both 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 aluminium (Al), and includes a first region, and a second region surrounding the first region, the second region being defined as a region having a thickness of about 1 micrometre (µm) in a direction from the outermost surface to the centre of the positive electrode active material. The content ratio of nickel to aluminium (NNi/NAl) of the second region is about 5 to about 45.