Anion-Binding Lithium Salts to Limit HF in Battery Electrolytes
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Solution Overview
Problem
Conventional lithium-ion batteries face safety concerns due to thermal runaway and manganese dissolution issues caused by lithium hexafluorophosphate (LiPF6) degradation, leading to toxic HF formation and reduced battery performance.
Innovation Solution
Development of purified lithium salts using anion binding agents (ABAs) that replace LiPF6, coordinating and binding free F- ions to form non-toxic complexes, thereby reducing thermal runaway and manganese dissolution, and synthesizing these salts through specific processes involving boron-based acids and fluorinated salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as electrolyte salt, then electrochemical performance is achieved, but toxic HF is formed through thermal degradation
Solution Approach 1:
The invention extracts and removes the problematic LiPF6 salt from the electrolyte system and replaces it with alternative lithium salts (LiClO4, LiBF4, LiPF5) combined with fluorinated cyclic carbonates. This extraction eliminates the primary source of HF generation while maintaining electrochemical functionality through the alternative salt composition.
Solution Approach 2:
The invention introduces fluorinated cyclic carbonate additives that actively bind to and neutralize HF through fluorine-lithium coordination. This converts the harmful HF byproduct into a stable complex, transforming the harmful effect into a beneficial neutralization process that protects the battery system.
2Duration of action of moving object
If LiPF6 is used as electrolyte salt, then battery operation is enabled, but manganese dissolution occurs reducing performance
Solution Approach 1:
The fluorinated cyclic carbonate additives bind to dissolved manganese ions through fluorine-lithium coordination, converting the harmful manganese dissolution into a beneficial stabilization process. This prevents manganese precipitation and maintains cathode material integrity throughout battery operation.
Solution Approach 2:
The fluorinated cyclic carbonate acts as an intermediary substance that mediates between the electrolyte and cathode materials. It forms protective coordination complexes that prevent direct harmful interactions between LiPF6 degradation products and manganese-containing cathodes, thereby reducing manganese dissolution.
3Adaptability or versatility
If LiPF6 is used as electrolyte salt, then electrochemical function is provided, but reactivity with battery materials increases
Solution Approach 1:
The invention extracts LiPF6 from the electrolyte composition and replaces it with alternative lithium salts combined with fluorinated cyclic carbonates. This removal eliminates the highly reactive LiPF6 that causes degradation of solvents and binders, while the alternative composition maintains necessary electrochemical functionality.
Solution Approach 2:
The fluorinated cyclic carbonate serves as an intermediary that reduces reactivity between the electrolyte salt and battery materials. It forms stable coordination complexes that prevent direct reactive interactions with solvents and binders, thereby reducing degradation while preserving electrochemical performance.
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 purified lithium salts provide enhanced chemical stability, reduce thermal runaway severity, and improve manganese stability in lithium-ion cells, ensuring safer and more predictable battery performance.
Implementation Method 1
the Lewis acid behavior of the anion binding agent (ABA) serves to coordinate and bind any free F— from HF or other sources to a non-toxic complex
Implementation Method 2
a process for synthesizing a purified lithium salt comprises the steps of dissolving at least one boron-based acid in a solvent to form a solution, refluxing the solution to form an anion binding agent, adding a stoichiometric amount of a small fluorinated salt to the anion binding agent to create a mixture, and crystallizing the mixture to obtain the purified lithium salt
Data Source
AI summary
A method for synthesizing a purified lithium (Li)+ anion binding agent (ABA-F)− salt and the corresponding Li+(ABA-F)− are disclosed. The method includes dissolving a boron-based acid in a polar solvent to form a solution. The solution is refluxed to form an anion binding agent. A stoichiometric amount of a small fluorinated salt, such as LiF, is added to the anion binding agent to form a mixture. The mixture is subsequently crystallized to obtain a substantially pure Li+(ABA-F)− salt. Example purified Li+(ABA-F)− salts include Ox-Li+(ABA-F), m-Li+(ABA-F), and BF3—Li+(ABA-F)−. These purified Li+(ABA-F)− salts provide the benefits of increased battery thermal safety without loss of electrochemical performance.