Li-Ion Battery Cathode Composition for High-CAE Electrolytes
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Solution Overview
Problem
The use of carboxylic acid ester (CAE) in lithium ion battery electrolyte solutions improves input/output characteristics but tends to decrease storage characteristics, making it challenging to increase the volume fraction of CAE without compromising battery performance.
Innovation Solution
Incorporating Li3PO4 into the positive electrode composite material and maintaining a volume fraction of CAE in the electrolyte solution at 20% or more, which promotes a stable protective film formation, reducing oxidation decomposition of CAE and thereby minimizing the decrease in storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the volume fraction of carboxylic acid ester (CAE) in the electrolyte solution is increased, then input/output characteristics are improved, but storage characteristics are decreased
Solution Approach 1:
Li3PO4 is introduced as an intermediary substance that mediates between the CAE and the positive electrode active material. It reacts with CAE to form a stable protective film that prevents direct contact and oxidation decomposition, thereby allowing high CAE content while maintaining storage characteristics
Solution Approach 2:
The oxidation decomposition of CAE at the positive electrode, which causes storage characteristic degradation, is converted into a beneficial process by forming a stable protective film through reaction with Li3PO4. This protective film prevents further decomposition and protects the electrode, transforming the harmful oxidation reaction into a protective mechanism
2Force
If the volume fraction of CAE in the electrolyte solution is increased, then viscosity is reduced and input/output characteristics are improved, but oxidation decomposition of CAE is increased
Solution Approach 1:
Li3PO4 acts as an intermediary that reacts with CAE to form a protective film, preventing direct oxidation decomposition. This allows high CAE content for low viscosity while the protective film prevents substance loss through oxidation
Solution Approach 2:
The protective film is formed preliminarily through the reaction between Li3PO4 and CAE before operational use. This pre-formed protective film prevents subsequent oxidation decomposition, allowing the system to maintain both low viscosity (high CAE content) and low substance loss
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 addition of Li3PO4 to the positive electrode composite material with a high volume fraction of CAE in the electrolyte solution effectively reduces the decrease in storage characteristics, enhancing the battery's overall performance by stabilizing the protective film and reducing CAE oxidation decomposition.
Implementation Method 1
the CAE tends to have a lower oxidation decomposition potential than that of a carbonate. It is considered that the decrease of the storage characteristics is promoted due to an increased amount of decomposition of the CAE in the positive electrode
Data Source
AI summary
A lithium ion battery includes a positive electrode, a negative electrode, and an electrolyte solution. The positive electrode includes a positive electrode composite material. The positive electrode composite material includes a positive electrode active material and Li3PO4. The electrolyte solution includes a lithium salt and a solvent. The solvent includes 20% or more of the carboxylic acid ester in volume fraction.