Cathode Particle Surface Coating for High-Temperature Li-Ion Stability
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in achieving both high initial charge-discharge efficiency and excellent high-temperature storage characteristics while maintaining high capacity, as previous technologies have not adequately addressed these requirements.
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 X including elements like P, Ca, Sr, B, Zr, or Al, which suppresses the elution of the sulfonate compound and protects the oxide from hydrogen fluoride, thereby improving both efficiency and high-temperature storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium-containing transition metal composite oxide is used as a positive electrode active material, then high capacity can be achieved, but initial charge-discharge efficiency and high-temperature storage characteristics are insufficient
Solution Approach 1:
The patent applies local quality by coating only the surface of the lithium-containing transition metal composite oxide particles with a specific compound layer containing P, Ca, Sr, B, Zr, Er, or Al elements. This surface modification locally changes the properties of the material without altering the bulk composition, thereby maintaining high capacity while improving high-temperature storage characteristics and initial charge-discharge efficiency.
Solution Approach 2:
The patent creates a composite material structure where a compound containing P, Ca, Sr, B, Zr, Er, or Al elements is combined with the lithium-containing transition metal composite oxide. This composite structure on the particle surface provides both high capacity (from the oxide core) and improved stability/resistance to degradation (from the protective compound layer), resolving the contradiction between capacity and reliability.
2Reliability
If the surface of lithium-containing transition metal composite oxide is coated with sulfonate compound, then initial charge-discharge efficiency is improved, but the sulfonate compound elutes at high temperatures
Solution Approach 1:
The patent introduces an intermediary compound containing P, Ca, Sr, B, Zr, Er, or Al elements that acts as a mediator between the sulfonate compound and the lithium-containing transition metal composite oxide. This intermediary layer prevents the elution of the sulfonate compound at high temperatures while maintaining its beneficial effect on initial charge-discharge efficiency, effectively resolving the contradiction between efficiency improvement and compositional stability.
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 enhances initial charge-discharge efficiency and high-temperature storage characteristics of non-aqueous electrolyte secondary batteries by reducing reaction resistance and protecting the lithium-containing transition metal composite oxide from hydrogen fluoride degradation.
Implementation Method 1
coated with a sulfonate compound and a compound X including elements like P, Ca, Sr, B, Zr, or Al, which suppresses the elution of the sulfonate compound and protects the oxide from hydrogen fluoride
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 contains secondary particles that are formed by aggregation of primary particles; a sulfonic acid compound expressed by formula (I) and a compound X that contains 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 compound X is present on the surfaces of the secondary particles with the sulfonic acid compound 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.)