Layered Cathode Surface Coating for High-Rate Charging Stability
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in achieving improved output characteristics and cycle characteristics during high-rate charging while maintaining high capacity, as hydrogen fluoride generation deteriorates the battery performance when using lithium-containing transition metal composite oxides with high nickel content.
Innovation Solution
A positive electrode active material comprising a lithium-containing transition metal composite oxide with a layered structure, coated with a sulfonate compound and a compound including elements like P, Ca, Sr, B, Zr, or Al, which reduces reaction resistance and protects the oxide from hydrogen fluoride, thereby enhancing output and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-containing transition metal composite oxide with high nickel content is used to increase capacity, then charge-discharge capacity is improved, but hydrogen fluoride generation deteriorates output characteristics and cycle characteristics during high-rate charging
Solution Approach 1:
A compound containing at least one element selected from P, Ca, Sr, B, Zr, Er, and Al is introduced as an intermediary substance between the lithium-containing transition metal composite oxide and the hydrogen fluoride generated during charging. This intermediary compound preferentially reacts with or protects against hydrogen fluoride, preventing its harmful effects on the oxide while allowing the oxide to maintain its high capacity function.
Solution Approach 2:
The compound containing P, Ca, Sr, B, Zr, Er, or Al is added in advance to the positive electrode active material before charging occurs. This preliminary action creates a protective effect that counteracts the harmful hydrogen fluoride generation that will occur during subsequent high-rate charging, thereby preserving output characteristics and cycle characteristics.
2Quantity of substance
If lithium-containing transition metal composite oxide with high nickel content is used to improve capacity, then charge-discharge capacity is increased, but reaction resistance increases during high-rate charging
Solution Approach 1:
The compound containing P, Ca, Sr, B, Zr, Er, or Al serves as a mediator that reduces reaction resistance during high-rate charging. It facilitates the electrochemical reactions at the positive electrode surface, allowing high current rates to be sustained without excessive resistance, while the high-nickel oxide maintains its capacity.
3Quantity of substance
If lithium-containing transition metal composite oxide is used to achieve high capacity, then charge-discharge capacity is improved, but the material becomes vulnerable to hydrogen fluoride attack
Solution Approach 1:
The harmful hydrogen fluoride generated during charging is converted into a beneficial protective mechanism. The compound containing P, Ca, Sr, B, Zr, Er, or Al reacts with hydrogen fluoride to form a protective layer or stable compounds, transforming the harmful substance into a protective element that shields the lithium-containing transition metal composite oxide from further degradation.
Solution Approach 2:
The compound containing P, Ca, Sr, B, Zr, Er, or Al acts as a protective intermediary between hydrogen fluoride and the lithium-containing transition metal composite oxide. It absorbs or neutralizes the hydrogen fluoride, preventing direct attack on the oxide structure and maintaining material integrity during high-rate charging.
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 results in a non-aqueous electrolyte secondary battery with improved output characteristics and cycle characteristics during high-rate charging, maintaining high capacity by reducing reaction resistance and protecting the composite oxide from hydrogen fluoride.
Implementation Method 1
a sulfonate compound and a compound including at least one element selected from the group consisting of P, Ca, Sr, B, Zr, and Al are present on surfaces of the secondary particles
Implementation Method 2
protecting the oxide from hydrogen fluoride, thereby enhancing output and cycle characteristics
Data Source
Figure 1
AI summary
A positive electrode active material for a non-aqueous electrolyte secondary battery according to the present disclosure comprises a lithium-containing transition metal composite oxide that has a layered structure, and is characterized in that: the lithium-containing transition metal composite oxide constitutes secondary particles that are formed by aggregation of primary particles; a sulfonic acid compound expressed by formula (I) and a compound X containing at least one element selected from the group consisting of P, Ca, Sr, B, Zr, Er, and Al are present on the surfaces of the secondary particles; and the sulfonic acid compound is present on the surfaces of the secondary particles with the compound X interposed therebetween. (In the formula, A is a group 1 element or a group 2 element, R is a hydrocarbon group, and n is 1 or 2.)