High-Nickel Cathode Material With Surface Aluminum Doping
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Solution Overview
Problem
High-nickel positive electrode active materials with nickel content of 80% or greater face rapid structural instability and performance deterioration when overcharged or exposed to high temperatures, limiting their application in lithium secondary batteries.
Innovation Solution
A method involving the preparation of a lithium composite transition metal oxide with a high nickel content, followed by washing and mixing with an aluminum raw material, then heat-treating at 650° C. to 690° C. to achieve a surface-doped aluminum positive electrode active material with a concentration gradient, enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in the positive electrode active material is increased to 80% or greater, then the capacity properties are improved, but the structural stability is rapidly reduced when overcharged or exposed to high temperature
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of aluminum doping where the surface region has higher aluminum content (0.1-0.5 mol ratio) compared to the interior. This localized doping strategy provides enhanced structural stability at the surface where degradation occurs most frequently during overcharge and high-temperature conditions, while maintaining high nickel content (80% or greater) in the bulk material for high capacity.
Solution Approach 2:
The patent creates a composite structure by combining high-nickel lithium composite transition metal oxide with aluminum doping. The resulting material has a composite composition where aluminum acts as a stabilizing component at the surface, forming a protective layer that maintains structural integrity during electrochemical cycling, overcharge, and high-temperature operation while preserving the high-capacity nickel-rich core.
2Stability of the object's composition
If aluminum doping is applied to improve structural stability, then the thermal stability is improved, but the doping process requires precise temperature control (650-690°C)
Solution Approach 1:
The patent specifies a narrow temperature range (650-690°C) for the heat treatment process to achieve optimal aluminum doping concentration and surface modification. This parameter optimization ensures that aluminum is properly incorporated into the surface region without excessive diffusion that would reduce the doping gradient effect, while avoiding temperatures that would cause material degradation or unwanted phase transformations.
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 resulting high-nickel positive electrode active material exhibits superior thermal stability, overcharge stability, and extended high-temperature lifespan, effectively addressing the limitations of existing materials.
Implementation Method 1
heat treating the mixture at a temperature of 650° C. to 690° C. to obtain a positive electrode active material having a surface portion doped with aluminum
Implementation Method 2
heat treating the mixture at a temperature of 650° C. to 690° C.
Data Source
AI summary
A method for producing a high-nickel positive electrode active material, a positive electrode active material produced thereby, and a positive electrode and a lithium secondary battery including the same is provided. The method includes preparing a lithium composite transition metal oxide having a nickel content of 80 atm % or greater among transition metals, washing the lithium composite transition metal oxide, and mixing the washed lithium composite transition metal oxide with an aluminum raw material and heat treating the mixture at a temperature of 650° C. to 690° C. to obtain a positive electrode active material having a surface portion doped with aluminum.