Solid Ionic Conductor Electrolyte for Low-Loss SO2 Rechargeable Cells
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Solution Overview
Problem
Conventional rechargeable batteries with liquid sulfur dioxide-containing electrolytes suffer from high capacity loss, internal resistance increase, and safety concerns due to self-discharge reactions, requiring large initial electrolyte quantities and complex drying processes.
Innovation Solution
A solid ionic conductor, such as sulfur dioxide-containing lithium thiodichloroaluminate (LiAlSCl2×q SO2), is used, which absorbs and releases sulfur dioxide reversibly, maintaining ionic conductivity and reducing internal pressure, allowing for a safer, more efficient battery design with reduced electrolyte quantity and increased energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid sulfur dioxide-containing electrolyte is used to achieve non-inflammability, then safety is improved, but self-discharge reactions occur causing capacity loss and internal resistance increase
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to solid by forming a solvate compound with a specific stoichiometric ratio (n≥4.5). This parameter change eliminates self-discharge reactions while maintaining non-inflammability, as the solid solvate structure prevents the chemical reactions that cause capacity loss in liquid electrolytes.
Solution Approach 2:
The patent creates a composite solid electrolyte system by combining lithium tetrachloroaluminate (LiAlCl4) and sulfur dioxide (SO2) in a specific ratio to form a solvate compound. This composite material integrates the non-inflammability of sulfur dioxide with the ionic conductivity of lithium salt, while the fixed stoichiometric structure prevents self-discharge reactions.
2Reliability
If large quantity of liquid electrolyte is used to compensate for self-discharge, then capacity is maintained, but device volume and weight increase
Solution Approach 1:
The patent changes the physical state from liquid to solid solvate, which has much lower vapor pressure and eliminates self-discharge reactions. This allows using minimal electrolyte quantity (just enough to fill pores) while maintaining capacity over 50,000 cycles, dramatically reducing the required electrolyte volume compared to liquid systems that require excess electrolyte to compensate for self-discharge.
3Manufacturing precision
If complex drying processes are used to achieve dryness of liquid electrolyte, then production precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the physical state to solid solvate with fixed stoichiometry, which inherently resists moisture absorption. This eliminates the need for complex multi-step drying processes required for liquid electrolytes, as the solid solvate can be handled with simple drying procedures while maintaining its composition and performance.
4Stress or pressure
If solid solvate LiAlCl4×3.0 SO2 is used to reduce internal pressure, then pressure is reduced, but ionic conductivity is practically zero
Solution Approach 1:
The patent changes the stoichiometric ratio parameter from n=3.0 to n≥4.5 (molar ratio of SO2 to LiAlCl4). This parameter change transforms the material from a non-conductive solid solvate to a highly conductive solid electrolyte, achieving both low internal pressure and high ionic conductivity simultaneously.
Solution Approach 2:
The patent creates a dynamic balance between the solid solvate structure and gaseous sulfur dioxide in the cell. The solid solvate provides structural stability and low pressure, while the gaseous SO2 maintains the stoichiometric ratio and enables ionic conductivity, allowing the system to adapt to temperature and pressure changes.
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 solid ionic conductor significantly reduces capacity loss and internal resistance, enabling high energy and power density with extended cycle life, improved safety, and lower production costs, while maintaining stable performance over 50,000 cycles.
Implementation Method 1
which absorbs and releases sulfur dioxide reversibly
Data Source
AI summary
The invention relates to a solid ionic conductor for a rechargeable non-aqueous electrochemical battery cell having the stoichiometric formula K(ASXX′)p×q SO2, where K represents a cation from the group of the alkali metals with p=1, of the alkaline-earth metals with p=2 or of the zinc group with p=2, A represents an element from the third main group, S represents sulfur, selenium or tellurium, X and X′ represent a halogen, and the numerical value q is greater than 0 and less than or equal to 100.