High-Entropy Core-Shell Cathode for Stable High-Nickel Cycling
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Solution Overview
Problem
Cathode active materials in battery cells, particularly those with high nickel content, suffer from thermal instability and surface instability issues, leading to reduced cycling life and safety concerns due to manganese/iron dissolution and O2 evolution.
Innovation Solution
A cathode active material is designed with a single crystal core encapsulated by a high entropy layer, which provides a stable surface structure, improving thermal stability and cycling life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content cathode active materials are used, then capacity and energy density are improved, but thermal stability and surface stability deteriorate
Solution Approach 1:
The patent employs a core-shell composite structure where the core is made of high-nickel cathode active material (NCM or NCMA) providing high capacity, and the shell is composed of a high-entropy alloy containing at least 5 different transition metal elements (such as Mn, Fe, Co, Ni, Cu, Zn, Al, Mg, Ti, Nb, Mo, W, or Zr). This composite structure allows the high-nickel core to deliver high capacity while the high-entropy shell provides thermal stability and surface protection, preventing manganese/iron dissolution and oxygen evolution. The shell acts as a protective barrier that maintains structural integrity during charging-discharging cycles.
2Quantity of substance
If high nickel content cathode active materials are used, then capacity is improved, but cycling life deteriorates
Solution Approach 1:
The core-shell composite structure with high-entropy alloy shell protects the high-nickel core from degradation during cycling. The shell's unique high-entropy configuration stabilizes the crystal structure and prevents phase transitions that typically occur during repeated charging-discharging cycles, thereby extending cycling life while maintaining high capacity.
Solution Approach 2:
The patent applies different material properties to different parts of the cathode active material: the core region uses high-nickel content material optimized for capacity, while the shell region uses high-entropy alloy material optimized for structural stability and surface protection. This local differentiation allows each region to perform its specific function optimally.
3Ease of manufacture
If conventional cathode active materials are used, then manufacturing is simpler, but thermal stability and surface stability deteriorate
Solution Approach 1:
The high-entropy alloy shell provides superior surface stability and thermal resistance compared to conventional coatings. The shell's unique configuration with at least 5 different transition metal elements creates a stable surface that resists degradation, manganese/iron dissolution, and oxygen evolution, while the manufacturing process integrates seamlessly with existing cathode production methods.
Data Source
AI summary
A cathode electrode includes a cathode current collector and a cathode active material layer arranged on at least one side of the cathode current collector. The cathode active material layer includes cathode active material comprising a plurality of cores each including a single crystal particle and a high entropy layer encapsulating each of the single crystal particles of the plurality of cores. The high entropy layer includes at least 5 different transition metal elements.