Composite O2-Type Positive Electrode for Low-Resistance Li-Ion Batteries
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Solution Overview
Problem
The positive electrode active material containing Li, Mn, and O with an O2 type structure exhibits high resistance in the redox region of Mn, leading to decreased capacity and increased resistance of the positive electrode as a whole.
Innovation Solution
Combining a first active material with Mn and O2 type structure and a second active material without Mn but with a transition metal and O2 type structure, such as Li, Co, and O, to form a positive electrode, where the second active material has low resistance in the redox region of Mn, thereby suppressing the overall resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material containing Li, Mn, and O with an O2 type structure is used, then the positive electrode can provide high capacity in general, but the resistance increases significantly in the redox region of Mn (3 V vs. Li/Li+ or less)
Solution Approach 1:
The patent combines two different positive electrode active materials: one containing Mn (providing high capacity) and one not containing Mn (providing low resistance). This composite approach allows the positive electrode to achieve both high capacity and low resistance by leveraging the complementary strengths of each material
Solution Approach 2:
The patent applies different material compositions to different regions or functional requirements within the positive electrode. The Mn-containing material addresses the capacity requirement while the Mn-free material addresses the resistance issue in specific potential regions, creating local optimization of properties
2Productivity
If the positive electrode uses active material with high Mn content to increase capacity, then the discharge capacity improves, but the resistance in the redox region of Mn increases, reducing overall performance
Solution Approach 1:
By creating a composite positive electrode active material comprising both Mn-containing and Mn-free components, the patent achieves high discharge capacity through the Mn-containing portion while the Mn-free portion compensates for resistance losses, thereby improving overall energy efficiency
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
This combination enhances the positive electrode capacity by reducing resistance, improving cycle characteristics, and maintaining high discharge capacity even at potentials up to 3 V (vs. Li/Li+).
Implementation Method 1
the resistance of the second active material is small even at a potential in the redox region of Mn, and an increase in resistance of the positive electrode as a whole is suppressed
Data Source
AI summary
A positive electrode includes a first active material and a second active material. The first active material contains at least Li, Mn, and O as constituent elements and includes an O2 type structure. The second active material contains at least Li, a transition metal element, and O as constituent elements but does not contain Mn, and includes the O2 type structure.