Ti-B Coated High-Nickel Cathode Material for Low-Temperature Output
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Solution Overview
Problem
High-nickel-based positive electrode active materials for lithium secondary batteries face challenges in maintaining sufficient output at low states of charge and low temperatures due to degraded output characteristics caused by increased resistance.
Innovation Solution
A positive electrode active material is developed with a lithium composite transition metal oxide containing 70 atm% or more nickel, coated with a layer containing titanium (Ti) and boron (B) in specific amounts (300 ppm to 800 ppm for Ti and 500 ppm to 1,000 ppm for B) to enhance structural stability and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a boron coating layer is formed on the surface of high-nickel-based positive electrode active material to improve structural stability, then structural stability is improved, but output characteristics are degraded due to increased resistance
Solution Approach 1:
The patent applies composite coating materials comprising both boron and aluminum on the surface of high-nickel-based positive electrode active material. The boron provides structural stability by suppressing contact with electrolyte solution, while the aluminum component maintains low resistance and excellent output characteristics. This composite coating approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent optimizes the thickness of the boron-containing coating layer to specifically 1 nm to 5 nm. This precise parameter control ensures that the coating is thin enough to maintain good electrical conductivity and output characteristics while being thick enough to provide sufficient structural stability. By carefully adjusting this critical parameter, the contradiction between stability and output performance is resolved.
2Quantity of substance
If nickel content in lithium composite transition metal oxide is increased to 70 at% or more to improve capacity characteristics, then capacity characteristics are improved, but structural stability deteriorates due to rapid crystal lattice degradation
Solution Approach 1:
The patent uses a composite coating system with boron and aluminum applied to high-nickel-based positive electrode active material containing 70 at% or more nickel. The boron forms a protective barrier that prevents crystal lattice degradation and maintains structural stability, while the aluminum component preserves electrical conductivity. This composite approach enables the high-nickel material to achieve both high capacity and structural stability.
Solution Approach 2:
The boron-containing coating layer is applied in advance to prevent contact between the high-nickel active material and the electrolyte solution before degradation can occur. This preliminary protective action suppresses crystal lattice degradation and oxygen release, maintaining structural stability throughout charge-discharge cycles despite the high nickel content that would otherwise cause rapid degradation.
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 proposed solution effectively maintains excellent output characteristics at low states of charge and low temperatures, making it suitable for high-capacity batteries in electric vehicles, while also improving structural stability and reducing process complexity.
Implementation Method 1
a method of improving the structural stability of the high-nickel-based positive electrode active material by suppressing a contact with an electrolyte solution by forming a coating layer on a surface of the positive electrode active material using boron (B)
Implementation Method 2
heat treating the mixture
Data Source
AI summary
A positive electrode active material and a method of preparing the same are disclosed herein. In some embodiments, a positive electrode active material includes a lithium composite transition metal oxide, and a coating layer formed on a surface of the lithium composite transition metal oxide includes titanium (Ti) and boron (B), wherein Ti is present in an amount of 300 ppm to 800 ppm and B is present in an amount of 500 ppm to 1,000 ppm based on a total weight of the positive electrode active material.