Metal Halide Electrolytes for Reversible Sodium and Lithium Batteries
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Solution Overview
Problem
Current sodium and lithium ion batteries face challenges in achieving high reversible capacity and cycle life due to limitations in electrolyte stability and anode-cathode interactions, particularly with sulfur and chlorine species, leading to reduced efficiency and safety concerns.
Innovation Solution
The development of a sodium or lithium ion battery with a carbonaceous cathode, a metal halide-based electrolyte containing thionyl chloride, and fluorinated compounds, which forms a stable solid-electrolyte interface, enabling reversible redox reactions and improved cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in sodium and lithium ion batteries, then the battery can operate with basic functionality, but the electrolyte stability is insufficient leading to reduced reversible capacity and cycle life
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing metal halides (AlCl3, NaCl, LiCl, GaCl3) in specific concentrations (0.5-6 M) combined with thionyl chloride and fluorinated compounds. This parameter modification transforms the electrolyte from unstable conventional formulations to a stable system that forms protective SEI layers, directly resolving the contradiction between electrolyte stability and cycle life.
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple components: metal halides, thionyl chloride, and fluorinated electrolyte compounds. This composite approach synergistically enhances electrolyte stability while the fluorinated compounds specifically contribute to forming stable solid-electrolyte interfaces, thereby improving both reliability and duration of battery operation.
2Reliability
If conventional electrolyte compositions are used, then the battery structure remains simple, but anode-cathode interactions with sulfur and chlorine species reduce efficiency and create safety concerns
Solution Approach 1:
The fluorinated electrolyte compounds act as intermediary substances that mediate between the reactive sulfur and chlorine species in the battery and the anode-cathode materials. These intermediaries form stable SEI layers that prevent harmful direct interactions, thereby improving safety while the metal halides provide the necessary ionic conductivity, balancing complexity and performance.
3Quantity of substance
If the battery uses high capacity materials, then the first discharge capacity increases, but the reversible capacity and cycling performance decrease due to electrolyte instability
Solution Approach 1:
The patent applies preliminary action by having the fluorinated electrolyte compounds and metal halides pre-form stable solid-electrolyte interface layers on the electrode surfaces before the battery undergoes cycling. This preliminary SEI formation prevents subsequent degradation reactions, allowing the battery to achieve both high first discharge capacity and maintained reversible capacity throughout cycling.
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 battery exhibits ultrahigh first discharge capacity and maintains high coulombic efficiency and energy efficiency throughout cycling, with enhanced cycle life and safety, attributed to the stable SEI formation and efficient redox reactions.
Implementation Method 1
fluorinated electrolyte compound, which forms a stable solid-electrolyte interface
Implementation Method 2
enabling reversible redox reactions and improved cycling performance
Implementation Method 3
an electrolyte including a metal halide, a fluorinated electrolyte compound, and thionyl chloride
Data Source
AI summary
An electrochemical device includes an anode having sodium or lithium; a cathode having a carbonaceous material; a separator; and an electrolyte that includes a metal halide, a fluorinated electrolyte compound, and thionyl chloride; wherein the electrochemical device is a primary battery or a secondary battery.