Lithium Fluorododecaborate Electrolyte Salt for Stable Battery Performance
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Solution Overview
Problem
Lithium-based electrolytes in batteries face issues with safety, oxidative stability, thermal stability, and the production of toxic HF, with specific salts like lithium hexafluorophosphate being unstable, lithium perchlorate having low thermal stability, and lithium hexafluoroarsenate causing arsenic toxicity.
Innovation Solution
The development of lithium secondary batteries using a lithium-based electrolyte salt of the formula Li2B12FxH12-x-yZy, where x+y is from 3 to 12, and Z comprises Cl and Br, which provides electrochemical, thermal, and hydrolytic stability, low impurity levels, and the ability to form low viscosity, low impedance electrolyte solutions that can be recycled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium hexafluorophosphate is used as electrolyte salt, then electrochemical performance is improved, but thermal stability deteriorates and HF production increases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte salt by introducing fluorinated dodecaborate structures with specific fluorine content (x=2-12) and hydroxyl substitution (y=0-6), replacing conventional salts like LiPF6. This compositional parameter change achieves both good electrochemical performance and improved thermal stability while reducing HF production.
2Reliability
If lithium perchlorate is used as electrolyte salt, then electrochemical performance is improved, but thermal stability deteriorates leading to explosive mixtures
Solution Approach 1:
The patent converts the potential harm of conventional electrolyte salts that produce explosive byproducts at high temperatures into a benefit by designing fluorinated dodecaborate salts that maintain electrochemical performance while eliminating the explosive decomposition pathway, achieving thermal stability above 200°C without explosive mixture formation.
3Reliability
If lithium hexafluoroarsenate is used as electrolyte salt, then electrochemical performance is improved, but arsenic toxicity increases
Solution Approach 1:
The patent extracts and removes the harmful arsenic element from the electrolyte salt composition entirely, replacing lithium hexafluoroarsenate with fluorinated dodecaborate salts that contain only lithium, boron, fluorine, hydrogen, and optional hydroxyl groups, thereby eliminating arsenic toxicity while preserving electrochemical performance.
4Reliability
If conventional electrolyte salts are used, then electrochemical performance is achieved, but purity and impurity levels deteriorate
Solution Approach 1:
The patent applies preliminary purification actions during the synthesis process by controlling reaction conditions (temperature 0-100°C, pH 2-12, specific reaction times) to minimize impurity formation, and by using filtration and washing steps to remove byproducts, achieving high purity electrolyte salts with controlled impurity levels below specified thresholds.
Data Source
AI summary
The present invention relates to lithium secondary batteries comprising a negative electrode, a positive electrode, a separator and a lithium-based electrolyte carried in an aprotic solvent, and to the electrolyte compositions, and to methods for purifying battery active materials. The electrolyte comprises at least one solvent and a lithium salt of the formula:Li2B12FxH12-x-yZy where x+y is from 3 to 12, and x and y are independently from 0 to 12, and Z comprises at least one of Cl and Br.