Core-Shell Ternary Precursor for High-Nickel Cathode Stability
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Solution Overview
Problem
High-nickel ternary positive electrode active materials in secondary batteries face challenges with structure stability and performance due to increased nickel content, affecting energy density and cycling characteristics.
Innovation Solution
A ternary precursor material with a core-shell structure is developed, where the core has a specific molecular formula and the shell includes a doping element, with controlled deformation stacking fault probability and breakage rate, enhancing structural stability and extractable capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in the ternary positive electrode active material is increased to achieve high gram capacity, then the energy density is improved, but the structure stability deteriorates
Solution Approach 1:
The positive electrode active material is divided into a core region (high-nickel ternary material) and a shell region (doped ternary material). The core contains 80-95 mol% nickel for high capacity, while the shell contains 5-20 mol% nickel with doping elements for structural stability. This spatial segmentation allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the material are given different compositions and properties. The core region is optimized for high nickel content to maximize capacity, while the shell region is optimized with doping elements and lower nickel content to provide structural stability and resistance to degradation. Each local region has tailored properties suited to its functional requirements.
2Quantity of substance
If the nickel content is increased to improve energy density, then the gram capacity is enhanced, but the cycling performance deteriorates
Solution Approach 1:
The material is segmented into core and shell regions where the core provides high capacity through high nickel content, while the shell protects the core during cycling through doping elements and optimized composition. The shell acts as a protective layer that maintains structural integrity during repeated charge-discharge cycles.
Solution Approach 2:
The positive electrode active material is a composite structure combining high-nickel ternary material in the core with doped ternary material in the shell. The doping elements (such as aluminum, titanium, or vanadium) in the shell create a composite material that exhibits both high capacity from the nickel-rich core and enhanced cycling stability from the doped shell structure.
3Quantity of substance
If high-nickel ternary material is used to achieve high gram capacity, then the energy density is improved, but the surface corrosion resistance deteriorates
Solution Approach 1:
The shell region is specifically engineered with doping elements and optimized nickel content to provide surface corrosion resistance. This local modification of the surface region protects the high-nickel core from electrolyte attack while maintaining the high capacity properties of the core material.
Solution Approach 2:
The doped shell material acts as an intermediary layer between the high-nickel core and the electrolyte. This intermediate shell with doping elements (such as aluminum, titanium, or vanadium) provides a protective barrier that reduces direct contact between the reactive high-nickel core and the electrolyte, thereby preventing surface corrosion.
Data Source
AI summary
Embodiments of this application provide a ternary precursor material, a preparation method thereof, and a positive electrode active substance. A ternary precursor material may be provided in this application and may include a core and a shell, wherein (1) the core may have a molecular formula of NixCoyMn1-x-y(OH)2±a, where 0.8≤x<1.0, 0<y<0.2, and 0<a<0.2; and the shell may include a doping element; and (2) a deformation stacking fault probability fD of the ternary precursor material may be ≤4%. With use of the positive electrode active substance prepared by sintering the precursor material, secondary batteries have relatively high gram capacity and cycling performance.