SO2 Electrolyte Battery Cell With Dual-Binder Electrode Stability
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Solution Overview
Problem
Existing rechargeable lithium-ion cells with organic electrolytes face safety risks due to flammability, thermal runaway, and reduced energy density, while SO₂-based electrolytes suffer from low solubility of conducting salts and instability at high charging potentials, leading to oxidative and reductive electrolyte decomposition.
Innovation Solution
A rechargeable battery cell design using an SO₂-based electrolyte with a first binder composed of monomeric styrene and butadiene units and a second binder of carboxymethylcellulose, along with planar electrodes, ensures high solubility and stability of conducting salts, preventing electrolyte decomposition and enhancing mechanical stability, while maintaining low vapor pressure and high ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic electrolytes are used in lithium-ion cells, then ionic conductivity is achieved, but safety risks arise due to flammability and thermal runaway
Solution Approach 1:
The patent replaces flammable organic electrolytes with an inert aqueous electrolyte solution containing SO2 and a conducting salt. The water-based electrolyte creates a non-flammable environment that eliminates thermal runaway risks while maintaining ionic conductivity through dissolved conducting salts, thus resolving the safety-flammability contradiction.
Solution Approach 2:
The patent changes the fundamental parameter of electrolyte composition from organic solvents to an aqueous SO2-based solution. This parameter change transforms the electrolyte's flammability characteristics while preserving its ionic conductivity function, directly addressing the safety concern without sacrificing electrical performance.
2Reliability
If SO2-based electrolytes are used, then non-flammability and safety are improved, but conducting salt solubility is reduced
Solution Approach 1:
The patent creates a composite electrolyte system combining SO2, water, and conducting salts in specific proportions. This composite approach enhances the solubility of conducting salts in the SO2-based medium while maintaining the non-flammable safety characteristics, thus resolving the contradiction between safety and ionic conductivity.
Solution Approach 2:
The patent introduces water as an intermediary substance that facilitates the dissolution of conducting salts in the SO2-based electrolyte. The water-SO2 mixture acts as a mediator that improves salt solubility while preserving the overall non-flammable nature of the electrolyte system.
3Strength
If conventional binders are used in electrodes, then mechanical stability is achieved, but oxidative electrolyte decomposition occurs at high charging potentials
Solution Approach 1:
The patent employs a binder system that forms a protective interface layer on the electrode surface, which acts as a sacrificial component that prevents direct contact between the electrolyte and electrode active materials. This protective layer decomposes preferentially, preserving the electrolyte stability while maintaining electrode mechanical integrity.
Solution Approach 2:
The patent uses a specialized binder as an intermediary substance between the electrode active materials and the SO2-based electrolyte. This binder forms a stable interface that prevents direct electrochemical reactions between the electrolyte and electrode components, thereby maintaining electrolyte stability while providing mechanical support to the electrode structure.
4Stability of the object's composition
If electrode coatings are applied to prevent electrolyte decomposition, then electrolyte stability is improved, but energy density is reduced
Solution Approach 1:
The patent employs a binder system that self-assembles into a protective interface layer on the electrode surface during initial charging cycles. This self-forming protective layer stabilizes the electrolyte without requiring additional coating materials that would increase electrode mass and reduce energy density, thus resolving the contradiction between electrolyte stability and energy density.
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 solution provides a rechargeable battery cell with improved safety, extended lifespan, high energy density, and enhanced operational reliability, supporting high charging potentials without electrolyte decomposition, and reduced self-discharge.
Implementation Method 1
At least one ion of the conducting salt (anion or cation) is mobile enough in the electrolyte to allow charge transport between the electrodes via ionic conduction
Implementation Method 2
The conducting salt is dissolved in the electrolyte and exhibits very good solubility. It can form a liquid solvate complex with gaseous SO2
Implementation Method 3
Above a certain upper cell voltage, the electrolyte undergoes oxidative electrochemical decomposition. This process often leads to the irreversible destruction of electrolyte components
Implementation Method 4
These electrochemical processes lead directly or indirectly to the release of electrons into the external circuit or the absorption of electrons from the external circuit
Implementation Method 5
The active metal of a rechargeable battery cell is the metal whose ions migrate within the electrolyte to the negative or positive electrode during charging or discharging of the cell
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a rechargeable battery cell (20, 40, 101) containing an active metal, at least one positive electrode (23, 44) with a planar discharge element (26), at least one negative electrode (22, 45) with a planar discharge element (27), a housing (28) and an SO2-based electrolyte containing a first conducting salt, wherein the positive (23, 44) and/or the negative electrode (22, 45) contains at least one first binder consisting of a polymer based on monomeric styrene and butadiene structural units, and at least one second binder from the group of carboxymethylcelluloses.