Phosphoric Acid Ester Amide Stabilizes LiPF6 Electrolyte
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Solution Overview
Problem
LiPF6 in nonaqueous secondary batteries lacks sufficient thermal stability, leading to decomposition and reduced battery performance, especially at high temperatures, due to its instability and reaction with trace water in the solvent, which decreases ion conductivity and causes corrosion.
Innovation Solution
Incorporating a phosphoric acid ester amide with a specific structure, containing both an amido group and an ester group, into the electrolyte solution to stabilize LiPF6, enhancing its thermal stability and oxidation resistance without altering its structure, thereby maintaining high ion conductivity and battery performance over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as the electrolyte in nonaqueous secondary batteries, then high ion conductivity and wide potential window are achieved, but thermal stability is insufficient leading to decomposition at high temperatures
Solution Approach 1:
A phosphoric acid ester amide is introduced as an intermediary substance that mediates between LiPF6 and the decomposition products. The additive preferentially reacts with PF5 to form stable complexes, preventing PF5 from catalyzing the decomposition of LiPF6 and solvent, thereby maintaining the integrity and ion conductivity of the electrolyte system
Solution Approach 2:
The invention changes the chemical environment parameters by introducing the phosphoric acid ester amide, which alters the reaction pathways and stability parameters of the electrolyte system. The additive modifies the thermal and chemical parameters to prevent decomposition while maintaining the functional properties of LiPF6
2Reliability
If LiPF6 is decomposed by heating or long-term storage, then ion conductivity decreases, but decomposition products cause corrosion and gas generation
Solution Approach 1:
The phosphoric acid ester amide performs preliminary anti-action by preemptively binding to PF5 decomposition products before they can catalyze further decomposition reactions. This preliminary complex formation prevents the chain reaction that would otherwise lead to solvent decomposition, corrosion, and gas generation, protecting the battery components in advance
3Stability of the object's composition
If fluorine atoms of LiPF6 are partially substituted by perfluoroalkyl group to increase thermal stability, then thermal stability improves, but oxidation resistance decreases
Solution Approach 1:
Instead of modifying LiPF6 structure, the invention uses phosphoric acid ester amide as an intermediary that provides thermal stability protection without affecting the oxidation resistance of LiPF6. The additive acts as a buffer that stabilizes thermal decomposition while leaving the electrochemical properties of LiPF6 intact
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 the phosphoric acid ester amide significantly improves the thermal and storage stability of LiPF6, maintaining high ion conductivity and battery performance even at elevated temperatures, preventing decomposition and corrosion, and ensuring stable battery operation.
Implementation Method 1
a phosphoric acid ester amide which has both an amido group and an ester group in one molecule
Implementation Method 2
an unstable intermediate produced by decomposition of LiPF6 is hydrolyzed by a trace amount of water contained in the solvent
Implementation Method 3
LiPF6 is decomposed by heating or in storage for a long period
Implementation Method 4
LiPF6 has high solubility in the solvent and high ion conductivity at a wide temperature range
Data Source
AI summary
A method for stabilizing a solution that contains LiPF6 by increasing thermal stability of LiPF6 without changing the structure thereof; an electrolyte solution for nonaqueous secondary batteries, which has increased thermal stability; and a nonaqueous secondary battery which has increased thermal stability. The solution containing LiPF6 contains a phosphoric acid ester amide in such an amount that the molar ratio of the phosphoric acid ester amide relative to LiPF6 is 0.001-2.