High-Ni Cathode Composition With Sr Coating for Cycle Stability
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Solution Overview
Problem
Lithium-transition metal composite oxides with high Ni content used in non-aqueous electrolyte secondary batteries experience destabilization of their layered structure during charge-discharge cycles, leading to reduced battery capacity and inferior charge-discharge cycle characteristics.
Innovation Solution
Incorporating specific amounts of Al and Sr into the lithium-transition metal composite oxide, along with substituting some Li in the Li layer with other metal elements, stabilizes the layered structure and forms a protective Sr coating on the negative electrode, enhancing the battery's charge-discharge cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lithium-transition metal composite oxide with high Ni content is used as positive electrode active material, then energy density is improved, but charge-discharge cycle characteristics deteriorate due to destabilization of layered structure
Solution Approach 1:
The patent applies local quality by introducing Sr elements specifically at the surface region of the lithium-transition metal composite oxide particles. The Sr content is controlled to be 0.01-5.0 wt% based on the total mass of the positive electrode active material, creating a Sr-enriched surface layer that stabilizes the structure during charge-discharge cycles while preserving the high Ni content (80-95 mol%) in the bulk material for high energy density.
Solution Approach 2:
The patent creates a composite material system by combining lithium-transition metal composite oxide (Li-Ni-Co-Al-O system) with Sr elements. This composite approach allows the high Ni content material to provide high energy density while the Sr component provides structural stabilization, achieving both high energy density and improved charge-discharge cycle characteristics simultaneously.
2Quantity of substance
If high Ni content (80-95 mol %) is used in lithium-transition metal composite oxide, then battery capacity is improved, but layered structure stability deteriorates during charging and discharging
Solution Approach 1:
The patent applies local quality by introducing Sr elements specifically at the surface region of the lithium-transition metal composite oxide particles. The Sr content is controlled to be 0.01-5.0 wt% based on the total mass of the positive electrode active material, creating a Sr-enriched surface layer that stabilizes the structure during charge-discharge cycles while preserving the high Ni content (80-95 mol%) in the bulk material for high energy density.
Solution Approach 2:
The patent creates a composite material system by combining lithium-transition metal composite oxide (Li-Ni-Co-Al-O system) with Sr elements. This composite approach allows the high Ni content material to provide high energy density while the Sr component provides structural stabilization, achieving both high energy density and improved charge-discharge cycle characteristics simultaneously.
Data Source
AI summary
A non-aqueous electrolyte secondary battery that is an exemplary embodiment of the present invention, wherein a positive electrode contains a lithium-transition metal composite oxide containing Ni, Al and Sr as a positive electrode active substance. In the lithium-transition metal composite oxide, the content of Ni is 80-95 mol %, the content of Al is 8.0 mol % or less, the content of Sr is 1.2 mol % or less, and the proportion of metallic elements other than Li that are present in a Li layer is 0.5-2.0 mol %. A negative electrode has a Sr-containing coating film formed on a surface of a negative electrode mixture layer. The content of Sr in the coating film is 20-400 ppm relative to the total mass of the negative electrode mixture layer and the coating film.