FEC Ratio Control for Battery Cycle Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current nonaqueous electrolyte secondary batteries do not consistently achieve high cycle characteristics, as the addition of fluoroethylene carbonate (FEC) to the electrolyte solution alone is insufficient to reliably improve their performance.
Innovation Solution
A nonaqueous electrolyte secondary battery configuration that includes a positive electrode, a negative electrode with a negative active material layer, and an electrolyte solution containing fluoroethylene carbonate, where the content of fluoroethylene carbonate (X) to the reaction area (Y) of the negative active material layer satisfies the relation 10≦(X/Y)≦100, ensuring optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoroethylene carbonate (FEC) is added to the electrolyte solution, then a coating is formed on the negative electrode and lithium ion diffusion is improved, but the cycle characteristics are not always improved reliably
Solution Approach 1:
The patent applies parameter changes by precisely controlling the FEC content relative to the negative active material layer area (X/Y ratio between 10-100). This quantitative parameter optimization ensures reliable cycle characteristics while avoiding the inconsistency of simply adding FEC without proper dosage control.
Solution Approach 2:
The patent uses partial action by adding only the necessary amount of FEC (not excessive) to form an adequate coating on the negative electrode. The controlled X/Y ratio ensures sufficient coating formation for protecting the electrode and improving lithium ion diffusion, while avoiding over-addition that would not further improve cycle characteristics.
2Reliability
If a coating is formed on the negative electrode by addition of FEC, then decomposition reaction of electrolyte solution is inhibited and capacity retention is improved, but the complexity of electrolyte composition increases
Solution Approach 1:
The patent applies local quality by forming a coating specifically on the negative electrode surface where it is most needed for protecting against electrolyte decomposition. The FEC concentrates at the negative electrode interface (where X/Y ratio is controlled) to provide localized protection, while the rest of the electrolyte composition remains relatively simple.
3Reliability
If the content of FEC is increased to improve cycle characteristics, then capacity retention improves, but the cost and complexity of electrolyte formulation increases
Solution Approach 1:
The patent optimizes the parameter of FEC content by establishing the X/Y ratio range (10-100), where X is FEC content in mg and Y is the reaction area of negative active material layer in m2. This parameter optimization achieves the best balance between cycle characteristics improvement and avoiding excessive FEC addition that would increase cost and complexity unnecessarily.
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 configuration effectively suppresses capacity reduction during charge-discharge cycles, resulting in a battery with high cycle characteristics, as the appropriate ratio of FEC to the reaction area enhances lithium ion conductivity and inhibits solvent decomposition, leading to improved durability and capacity retention.
Implementation Method 1
the decomposition reaction of an electrolyte solution in the negative electrode is inhibited
Implementation Method 2
the diffusion and acceptance of lithium ions in the negative electrode are improved
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode and an electrolyte solution, wherein the negative electrode includes a negative active material layer, the electrolyte solution contains fluoroethylene carbonate, and when a content (mg) of the fluoroethylene carbonate is denoted as X and a reaction area (m2) of the negative active material layer is denoted as Y, X and Y satisfy a relation of 10≦(X/Y)≦100.