Lithium-Sulphur Battery Eutectic Electrolyte for Low-Temperature Operation
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Solution Overview
Problem
Current non-aqueous electrolyte compositions for lithium batteries face challenges in achieving high cycling efficiency, temperature stability, safety, and low solvent volatility, particularly due to reactivity with lithium anodes, leading to limited cycle life and safety concerns.
Innovation Solution
A non-aqueous electrolyte composition comprising a eutectic or near-eutectic mixture of aprotic solvents and electrolyte salts, along with additives for improved solid electrolyte interface formation, is used to enhance ionic conductivity and stability, suitable for both lithium metal and lithium-ion anodes, with specific solvents like tetrahydrofuran and sulfones, and salts like LiPF6, to extend cycle life and improve low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional non-aqueous electrolyte compositions are used, then the battery can operate, but the cycling efficiency is poor and cycle life is limited due to reactivity with lithium anodes
Solution Approach 1:
The patent applies preliminary action by forming a stable solid electrolyte interface (SEI) layer on the lithium anode surface through specific electrolyte additives before the main electrolyte can react with the anode. This pre-formed protective layer prevents subsequent harmful reactions between the conventional electrolyte and lithium, thereby extending cycle life while maintaining operational functionality.
Solution Approach 2:
The patent introduces intermediary substances (electrolyte additives) that act as mediators between the lithium anode and the conventional electrolyte. These additives form intermediate protective layers that prevent direct contact and harmful reactions between lithium and the main electrolyte composition, resolving the contradiction between maintaining battery operation and reducing reactivity.
2Reliability
If conventional electrolyte compositions are used, then the battery can function, but safety is compromised due to solvent volatility and thermal instability
Solution Approach 1:
The patent applies composite materials by combining conventional electrolyte solvents with specific additives and co-solvents to create a composite electrolyte composition. This composite structure maintains the ionic conductivity of conventional electrolytes while the added components provide thermal stability and reduce volatility, thereby improving safety without sacrificing functional performance.
Solution Approach 2:
The patent employs parameter changes by modifying the chemical composition parameters of the electrolyte system through the addition of specific compounds. These compositional changes alter the thermal and volatility properties of the electrolyte, transforming it from a volatile, thermally unstable conventional electrolyte to a safer composition with improved thermal stability while maintaining operational functionality.
3Adaptability or versatility
If conventional electrolyte compositions are used, then the battery can operate, but low-temperature performance is poor due to high viscosity
Solution Approach 1:
The patent applies parameter changes by modifying the viscosity parameters of the electrolyte through the addition of low-viscosity co-solvents and additives. These compositional adjustments maintain the electrolyte's ionic conductivity while significantly reducing its viscosity, thereby enabling the battery to operate effectively at low temperatures where conventional high-viscosity electrolytes would fail.
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 proposed electrolyte composition significantly improves low-temperature performance, extends battery cycle life, and enhances safety by maintaining high ionic conductivity and stability, while being cost-effective and compatible with various lithium-based battery types.
Implementation Method 1
Desirable electrolyte elements provide high cycling efficiency, good ionic conductivity, good thermal stability
Implementation Method 2
additives for improved solid electrolyte interface formation
Implementation Method 3
the concentrations of the components of the solution are selected so that the solution is at its eutectic concentration or within at most ±30% of its eutectic concentration
Data Source
AI summary
An electrolyte for a lithium-sulphur battery, the electrolyte comprising a solution of at least one electrolyte salt in at least two aprotic solvents. The components of the solution may be selected so that the solution is eutectic or close to eutectic. Also disclosed is a lithium-sulphur battery including such an electrolyte. By using a eutectic mixture, the performance of the electrolyte and the battery at low temperatures is much improved.