Nb-Doped High-Ni Cathode for Battery Cycle Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-transition metal composite oxides with high Ni content and low Co content exhibit unstable structures, leading to side reactions with electrolytes and deterioration of charge-discharge cycle characteristics in non-aqueous electrolyte secondary batteries.
Innovation Solution
Incorporating Nb into the lithium-transition metal composite oxide as a positive electrode active material, with specific content ranges for Ni, Nb, and Co, and forming a Nb coating on the negative electrode surface to inhibit decomposition product formation and enhance cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Co content is reduced in high Ni content lithium-transition metal composite oxide, then the cost is reduced, but the structure stability deteriorates leading to side reactions with electrolyte
Solution Approach 1:
Nb acts as an intermediary element between Ni and the electrolyte. The patent introduces Nb into the composite oxide structure, where it forms a stable phase that mediates the interaction between the high-Ni cathode material and the electrolyte, preventing direct harmful reactions while maintaining structural integrity.
Solution Approach 2:
The patent creates a composite material system by incorporating Nb into the lithium-transition metal composite oxide. This composite approach combines the high capacity benefits of Ni with the structural stability provided by Nb, forming a new material phase that exhibits both high energy density and improved stability.
2Use of energy by moving object
If high Ni content lithium-transition metal composite oxide is used, then the energy density is improved, but the cycle characteristics deteriorate due to structure instability
Solution Approach 1:
The patent applies local quality by concentrating Nb at specific locations within the composite oxide structure. Rather than uniformly distributing all elements, Nb is strategically positioned to provide localized structural support and stability enhancement where most needed, while maintaining the overall high-Ni composition for energy density.
Solution Approach 2:
The patent changes the compositional parameters by introducing Nb at specific concentration ranges (0.01-0.5 mol%). This parameter adjustment transforms the material properties, enabling the composite oxide to maintain structural stability during cycling while preserving high energy density characteristics.
3Object-generated harmful factors
If decomposition products of electrolyte are generated, then the coating on negative electrode surface is formed, but the charge-discharge cycle characteristics deteriorate
Solution Approach 1:
The patent applies preliminary anti-action by using Nb to prevent the formation of harmful decomposition products before they can form. Nb creates a stable interface that preemptively blocks the chemical reactions between the cathode material and electrolyte that would otherwise generate decomposition products and harmful coatings on the negative electrode.
Data Source
AI summary
A secondary battery with a positive electrode comprises, as a positive electrode active material, a lithium-transition metal compound oxide containing Ni, Nb, and an optional component, Co. The content of Ni in the lithium-transition metal compound oxide is 80 mol % or more relative to the total molar number of metallic elements excluding Li, the content of Nb is 0.35 mol % or less relative to the total molar number of metallic elements excluding Li, and the content of Co is 5 mol % or less relative to the total molar number of metallic elements excluding Li. A negative electrode has a negative electrode mixture layer containing a negative electrode active material, and a film containing Nb formed on a surface of the negative electrode mixture layer. The content of Nb in the film relative to the total mass of the negative electrode mixture layer and the film is 10 to 3000 ppm.