Nickel-Rich Cathode Cladding to Reduce Lithium Impurities
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Solution Overview
Problem
Secondary batteries with high nickel content positive electrode active materials have high lithium impurity content, which adversely affects battery performance.
Innovation Solution
A positive electrode material with a cladding layer containing sulfur, selenium, or tellurium elements is applied to the surface of the nickel-rich LiNi1−xMxO2 active material, reacting with lithium impurities to reduce their content and improve cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content positive electrode active material is used, then specific capacity is improved, but cycle performance deteriorates
Solution Approach 1:
The cladding layer serves as a protective intermediary that stabilizes the interface between the high nickel content active material and the electrolyte. By reacting with lithium impurities and forming a stable surface layer, it prevents degradation reactions that would otherwise occur during cycling, thereby improving cycle performance while maintaining high specific capacity.
Solution Approach 2:
The invention creates a composite structure consisting of the high nickel content positive electrode active material (LiNi1-xMxO2) core and a cladding layer containing sulfur, selenium, or tellurium elements. This composite material combines the high capacity characteristics of the nickel-rich core with the stabilizing and protective properties of the cladding layer, achieving both high specific capacity and improved cycle performance.
2Quantity of substance
If cladding layer is added to positive electrode active material, then lithium impurity content is reduced, but device complexity increases
Solution Approach 1:
The cladding layer is designed as a thin film coating on the surface of the positive electrode active material particles. This thin film structure effectively reduces lithium impurity content without adding significant structural complexity or volume. The cladding layer forms a protective shell that is thin enough to maintain good ionic conductivity while being thick enough to effectively sequester lithium impurities.
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 cladding layer reduces lithium impurities, enhances slurry flowability and coating performance, stabilizes the electrode surface, and improves battery capacity and cycle life by forming a stable electrolyte interphase film.
Implementation Method 1
the cladding layer including at least one of the sulfur element, the selenium element, and the tellurium element is introduced to the surface of the positive electrode active material. When the positive electrode material is used to prepare a secondary battery, the cladding layer may react with a lithium impurity of the positive electrode active material
Implementation Method 2
improves battery capacity and cycle life by forming a stable electrolyte interphase film
Data Source
AI summary
A positive electrode material includes a positive electrode active material and a cladding layer located on at least a part of a surface of the positive electrode active material. The positive electrode active material includes a material whose chemical formula is LiNi1−xMxO2, 0≤x≤0.2, M includes at least one of Co, Mn, Al, Fe, Cu, and V, and the cladding layer includes at least one of a sulfur element, a selenium element, and a tellurium element. When the positive electrode material is used to prepare a secondary battery, the cladding layer may react with a lithium impurity of the positive electrode active material, to reduce a lithium impurity content of the positive electrode active material of the secondary battery and improve cycle performance of the battery.