Ether Electrolyte Composition for Low-Temperature Sodium Metal Batteries
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Solution Overview
Problem
Sodium metal batteries exhibit poor cycle performance under low-temperature conditions due to insufficient sodium salt dissociation capability and crystallization of electrolytes, leading to reduced conductivity and uneven sodium ion deposition.
Innovation Solution
An electrolyte comprising ethylene glycol dimethyl ether and an ether compound represented by general formula I, with specific mass ratios and concentrations of sodium salts, is used to maintain sodium salt dissociation and prevent crystallization, enhancing conductivity and cycle performance under both room temperature and low-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene glycol dimethyl ether is used as the main solvent, then sodium salt dissociation capability is improved at room temperature, but crystallization occurs and conductivity deteriorates at low temperature
Solution Approach 1:
The patent combines ethylene glycol dimethyl ether with ether compounds of formula I in a synergistic mixture. The ethylene glycol dimethyl ether provides strong sodium salt dissociation capability at room temperature, while the ether compound of formula I prevents crystallization and maintains conductivity at low temperatures, resolving the contradiction between room temperature performance and low temperature stability.
Solution Approach 2:
The electrolyte uses a composite solvent system comprising ethylene glycol dimethyl ether and ether compounds of formula I. This composite material approach allows the electrolyte to exhibit both strong sodium salt dissociation capability at room temperature and resistance to crystallization at low temperatures, achieving properties that neither component could provide alone.
2Reliability
If the mass percentage of ethylene glycol dimethyl ether is increased, then sodium salt dissociation capability is enhanced, but low-temperature performance deteriorates due to crystallization
Solution Approach 1:
The patent optimizes the mass percentage of ethylene glycol dimethyl ether within the range of 5% to 50% in the non-aqueous solvent. This parameter optimization ensures sufficient sodium salt dissociation capability while preventing crystallization at low temperatures. The specific concentration range balances the competing requirements of dissociation strength and low-temperature fluidity.
3Ease of manufacture
If conventional electrolytes are used, then manufacturing simplicity is maintained, but cycle performance under low-temperature conditions is poor
Solution Approach 1:
The patent modifies the electrolyte composition by introducing ether compounds of formula I with specific structural parameters (R1, R2 as alkyl groups with 1-6 carbon atoms, R3 as alkylene groups with 1-5 carbon atoms, and n as integers from 1 to 5). These parameter changes improve low-temperature cycle performance while maintaining reasonable manufacturing simplicity through the use of well-defined chemical structures.
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 electrolyte maintains high ionic conductivity and improves cycle performance of sodium metal batteries even at low temperatures, preventing crystallization and ensuring effective sodium ion transport.
Implementation Method 1
an electrolyte, including a non-aqueous solvent and a sodium salt dissolved in the non-aqueous solvent
Implementation Method 2
maintains high ionic conductivity and improves cycle performance of sodium metal batteries
Data Source
AI summary
An electrolyte for a sodium metal battery is disclosed. The electrolyte includes a non-aqueous solvent and a sodium salt. The non-aqueous solvent comprises an ether solvent that includes ethylene glycol dimethyl ether and one or more compounds represented by a general formula: R1—(O—R3)n—O—R2, where R1 and R2 are independently selected from C1-C6 alkyl groups, R3 is selected from a C1-C5 alkylene group, and n is an integer from 2 to 5; or R1 and R2 are selected from C2-C6 alkyl groups, R3 is a C1-C5 alkylene group, and n is 1. The mass percentage of ethylene glycol dimethyl ether ranges from 5% to 50%. The electrolyte improves the cycle performance of the sodium metal battery, particularly under low-temperature conditions.