Electrolyte Salts for Conductive SEI and Low-Hygroscopicity Cells
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Solution Overview
Problem
Current lithium salts used in battery electrolytes, such as LiPF6, LiFSI, and LiTFSI, face issues like degradation, corrosion, high costs, and hygroscopicity, which affect ionic conductivity and stability, particularly at high voltages and in the presence of water.
Innovation Solution
Development of new salts defined by specific chemical formulas (I to V) that include metal cations like Li, Na, or K, with functional groups like NHSO2R4 and SO2NHSO2R4, which improve ionic conductivity, solubility, and SEI formation, reducing production costs and hygroscopicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used in battery electrolytes, then ionic conductivity is improved, but stability deteriorates due to degradation and HF formation
Solution Approach 1:
The patent modifies the chemical structure of lithium salts by changing the anion composition from traditional PF6- to new fluorosulfonate-based anions with specific molecular structures (Formula I-V). This parameter change in chemical composition eliminates HF formation while maintaining ionic conductivity, directly resolving the contradiction between stability and harmful byproduct generation.
Solution Approach 2:
The invention creates composite electrolyte systems by combining lithium salts with new fluorosulfonate anions with specific solvents (carbonates, carboxylic acid esters, cyclic carbonates). This composite approach maintains the beneficial ionic conductivity of traditional salts while eliminating their degradation issues through synergistic interactions in the electrolyte composition.
2Reliability
If LiTFSI is used to improve stability, then corrosion resistance is improved, but cost increases and high voltage performance deteriorates
Solution Approach 1:
The patent changes the chemical parameters of lithium salt anions to fluorosulfonate structures with specific molecular configurations (Formula I-V). These structural modifications provide corrosion resistance comparable to or better than LiTFSI while using more cost-effective synthesis routes and avoiding the high cost associated with TFSI-based salts.
3Reliability
If LiFSI or LiTFSI is used, then stability is improved, but solubility and conductivity issues arise
Solution Approach 1:
The invention modifies the anion structure parameters of lithium salts to create fluorosulfonate-based salts with optimized molecular structures (Formula I-V). These structural changes enhance solubility in common electrolyte solvents while maintaining stability, directly addressing the solubility-conductivity issues of LiFSI and LiTFSI.
4Reliability
If LiTDI is used to improve stability, then corrosion resistance is improved, but hygroscopicity increases and conductivity decreases
Solution Approach 1:
The patent changes the chemical structure of lithium salt anions from TDI to fluorosulfonate structures (Formula I-V). This parameter change in molecular structure reduces hygroscopicity while maintaining corrosion resistance, and the specific fluorosulfonate structure enhances ionic conductivity compared to LiTDI.
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 new salts enhance ionic conductivity, reduce production costs, and improve solubility in electrolyte solvents, forming a more conductive Solid Electrolyte Interphase (SEI), addressing the limitations of existing salts and enabling more stable battery performance.
Implementation Method 1
improve solubility in electrolyte solvents
Implementation Method 2
forming a more conductive Solid Electrolyte Interphase (SEI)
Data Source
AI summary
The present disclosure relates to compounds for use as electrode additives or as salts in electrolyte compositions, and their methods of preparation. The majority of compounds are anions of imidazoles bearing a sulphonyl or a carbonyl group, or other nitrogen-containing conjugated with various heterocyclic or sulfonyl groups. Also described are some electrochemical cells comprising the compounds as electrode additives or as salts in electrolyte compositions.