Sodium Ion Battery Electrolyte SEI Formation for Thermal Stability
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Solution Overview
Problem
Sodium ion batteries face challenges in achieving high-temperature stability, initial discharge capacity, and electrode stability, particularly with the dissolution of metals like manganese, which affects their lifetime and performance.
Innovation Solution
The use of an electrolyte composition comprising sodium monofluorophosphate (Na2PO3F) or sodium difluorophosphate (NaPO2F2) forms a Solid Electrolyte Interface (SEI) and includes conducting salts like NaPF6 and additives such as monofluoroethylene carbonate, enhancing thermal stability and preventing electrolyte decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte compositions are used in sodium ion batteries, then the battery can operate, but thermal stability deteriorates at high temperatures and electrode decomposition occurs
Solution Approach 1:
The patent introduces a film-forming additive as an intermediary substance that mediates between the electrolyte and electrode. This additive preferentially reacts to form a protective SEI film that acts as a barrier, preventing direct contact and harmful reactions between the electrolyte and electrode materials at high temperatures, thus resolving the contradiction between thermal stability and electrode stability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific film-forming additives with controlled concentrations. This parameter change enables the electrolyte to form stable protective films on electrode surfaces, transforming the electrolyte's properties to achieve both high-temperature stability and electrode protection simultaneously.
2Duration of action of moving object
If conventional electrolyte compositions are used, then the battery structure is simple, but initial discharge capacity and lifetime are insufficient
Solution Approach 1:
The patent creates a composite electrolyte system by combining conventional electrolyte components with specialized film-forming additives. This composite approach leverages the benefits of each component: the base electrolyte provides ionic conductivity while the additive components form protective films, achieving extended battery lifetime through synergistic material composition.
Solution Approach 2:
The film-forming additives perform preliminary action by reacting first during initial charging cycles to form stable SEI films on electrode surfaces. This preliminary film formation prevents subsequent electrolyte decomposition and electrode degradation during normal operation, thereby extending battery lifetime without requiring complex structural modifications.
3Reliability
If standard electrolyte compositions are used, then manufacturing is simple, but metal dissolution occurs affecting performance
Solution Approach 1:
The film-forming additive serves as an intermediary protective layer between the electrolyte and metal electrodes. This additive preferentially reacts to form a stable SEI film that acts as a barrier, preventing metal dissolution into the electrolyte while maintaining manufacturing simplicity through straightforward electrolyte preparation processes.
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
This configuration improves the sodium ion battery's thermal stability, initial discharge capacity, and extends its lifetime by preventing electrode decomposition and metal dissolution, especially at high temperatures.
Implementation Method 1
the sodium compound selected from the group of sodium monofluorophosphate, sodium difluorophosphate and mixture thereof can advantageously form SEI (Solid Electrolyte Interface) in the sodium ion battery, for example on the surface of cathode and/or anode
Implementation Method 2
cations in the electrolyte composition enabling electrons to keep flowing to conduct electricity in the battery system usually comprise sodium ions as main conducting-cations
Data Source
AI summary
Disclosed is an electrolyte composition, suitable for sodium ion battery, comprising at least one sodium compound selected from the group consisting of sodium monofluorophosphate (Na2PO3F), sodium difluorophosphate (Na PO2F2) and mixture thereof, and a sodium ion battery comprising the same.