LixMeyOαFβ Positive Electrode for Battery Reliability
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Solution Overview
Problem
Existing batteries suffer from insufficient reliability due to side reactions occurring at the interface between the electrolytic solution and the positive electrode active material, leading to reduced discharge efficiency and capacity.
Innovation Solution
A battery design featuring a positive electrode active material with a crystal structure belonging to the FM3-M space group, represented by the compositional formula LixMeyOαFβ, where Me includes elements like Mn, Co, Ni, and F, and a nonaqueous solvent with a fluoro group, which prevents side reactions by increasing the distance between the positive electrode active material and the solvent, thereby enhancing reliability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active materials are used, then battery capacity can be achieved, but side reactions occur at the interface between electrolytic solution and positive electrode active material leading to insufficient reliability
Solution Approach 1:
A coating layer comprising at least one of a metal oxide and a metal hydroxide is formed on the surface of the positive electrode active material. This coating layer acts as an intermediary between the electrolytic solution and the positive electrode active material, preventing direct contact and thereby suppressing side reactions at the interface while maintaining battery reliability.
2Quantity of substance
If large Li extraction is performed to increase capacity, then battery capacity increases, but crystal structure stability deteriorates
Solution Approach 1:
A coating layer is formed beforehand on the surface of the positive electrode active material before large Li extraction is performed. This pre-formed coating layer cushions and protects the crystal structure from degradation during extensive Li extraction, enabling high capacity while maintaining structural stability.
Solution Approach 2:
The positive electrode active material is combined with a coating layer comprising metal oxide and/or metal hydroxide, creating a composite structure. This composite material approach allows the core active material to provide high capacity through large Li extraction while the outer coating layer maintains crystal structure stability.
3Productivity
If interface contact between electrolytic solution and positive electrode active material is increased to improve ion transfer, then ion transfer efficiency improves, but side reactions increase
Solution Approach 1:
The coating layer serves as an intermediary that facilitates ion transfer between the electrolytic solution and positive electrode active material while simultaneously preventing harmful side reactions. The coating layer is designed to be ion-conductive yet chemically stable, allowing productive ion exchange without direct harmful contact.
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 battery achieves high reliability and capacity by preventing side reactions and maintaining a stable rock salt crystal structure even with large Li extraction, resulting in a higher-capacity lithium ion battery with improved discharge efficiency.
Implementation Method 1
The nonaqueous solvent includes a solvent having at least one fluoro group. The solvent having at least one fluoro group prevents side reactions by increasing the distance between the positive electrode active material and the solvent
Data Source
AI summary
A battery includes a positive electrode including a positive electrode active material, a negative electrode, and an electrolytic solution including a nonaqueous solvent. The positive electrode active material includes a compound having a crystal structure belonging to a space group FM3-M and represented by Compositional Formula (1): LixMeyOαFβ, where, Me is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr; and subscripts x, y, α, and β satisfy the following requirements: 1.7≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.5, and 0.5≤β≤2. The nonaqueous solvent includes a solvent having at least one fluoro group.