Battery Electrolyte Solvent Mix for Low-Temperature Cycle Stability
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Solution Overview
Problem
Secondary batteries with metal negative electrodes, especially those with no negative electrode, face challenges such as poor cycling capabilities, high electrolyte salt concentration, high viscosity, and low ionic conductivity, which hinder both room temperature and low-temperature performance.
Innovation Solution
The development of an electrolyte comprising a solvent mixture of at least one cyclic ether of formula (I) and at least one linear ether of formula (II), which enhances the battery's cycle life and low-temperature capacity retention by improving ionic conductivity and reducing viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentration electrolytic salt is used to improve room temperature cycling performance, then cycling stability is improved, but viscosity increases and ionic conductivity decreases
Solution Approach 1:
The patent uses a composite solvent system comprising cyclic carbonate, chain carbonate, and cyclic carboxylate in specific ratios. This composite approach allows the electrolyte to maintain high ionic conductivity while providing adequate viscosity and cycling stability, resolving the contradiction between cycling performance and flow properties.
Solution Approach 2:
The patent optimizes the concentration of electrolytic salt within a specific range (1.0-3.0 M) rather than using high concentrations. It also carefully controls the ratios of different solvent components to achieve the desired balance between ionic conductivity, viscosity, and cycling stability.
2Reliability
If high concentration electrolytic salt is used to improve room temperature cycling performance, then cycling stability is improved, but ionic conductivity decreases
Solution Approach 1:
The patent employs a composite solvent system with cyclic carbonate, chain carbonate, and cyclic carboxylate that works synergistically to maintain high ionic conductivity while supporting cycling stability at moderate electrolyte concentrations.
Solution Approach 2:
The patent identifies and implements optimal parameter ranges: electrolytic salt concentration of 1.0-3.0 M and specific solvent ratios, which maximize ionic conductivity while maintaining adequate cycling performance.
3Ease of operation
If conventional electrolyte composition is used to achieve low viscosity, then low-temperature capacity release is improved, but cycling life decreases
Solution Approach 1:
The patent uses a composite solvent system comprising cyclic carbonate, chain carbonate, and cyclic carboxylate in specific ratios. This combination provides the right balance of low viscosity for low-temperature performance and chemical stability for long cycle life.
Solution Approach 2:
The patent optimizes the ratios of different solvent components and electrolytic salt concentration to achieve the sweet spot where viscosity is low enough for good low-temperature performance but high enough to maintain cycling stability.
4Reliability
If electrolyte is optimized for room temperature performance, then cycling stability is improved, but low-temperature capacity release capability decreases
Solution Approach 1:
The patent employs a multi-component solvent system where cyclic carbonate provides stability, chain carbonate provides low viscosity, and cyclic carboxylate enhances overall performance, achieving both cycling stability and low-temperature capability.
Solution Approach 2:
The patent determines optimal concentration ranges and solvent ratios that simultaneously satisfy both room temperature cycling stability requirements and low-temperature capacity release requirements.
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 proposed electrolyte solution enables secondary batteries with metal negative electrodes to achieve long cycle life and high low-temperature capacity retention in a wide temperature range, addressing the limitations of current electrolytes.
Implementation Method 1
electrolytes currently used in secondary batteries with metal negative electrode often come with issues such as high concentration (that is, high electrolytic salt concentration), high viscosity, and low ionic conductivity
Implementation Method 2
high viscosity, and low ionic conductivity, making it difficult to ensure both low-temperature capacity release capability and long cycle life
Data Source
AI summary
An electrolyte includes a solvent, where the solvent includes at least one cyclic ether of formula (I) and at least one linear ether of formula (II).where A1 is an oxygen atom, a single bond, or CHR4, A2 is an oxygen atom or CHR5, A2 is different from A1, and when A1 is CHR4, A2 is not CHR5, R1, R2, and R5 are each independently a hydrogen atom, C1-6 alky, or C1-6 fluoroalkyl, R3 and R4 are each independently a hydrogen atom, a fluorine atom, C1-6 alkyl, or C1-6 fluoroalkyl, R1 to R5 comprise 1 to 3 fluorine atom, R6 is a hydrogen atom, a fluorine atom, C1-6 alkyl, or C1-6 fluoroalkyl, and R7 is a hydrogen atom, C1-6 alkyl, or C1-6 fluoroalkyl