Diluted Concentrated Battery Electrolytes for Low-Flammability Conductivity
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Solution Overview
Problem
Conventional electrolytes for lithium-ion battery cells have high volatility and flammability, leading to safety concerns such as fires and explosions, and they also face challenges like increased cost and reduced lithium-ion conductivity due to high salt concentrations.
Innovation Solution
The development of diluted concentrated electrolytes, which incorporate a concentrated active salt in a solvent at concentrations greater than 1 mole/liter, combined with a diluent that disperses the salt and solvent into localized regions, significantly reducing free solvent and vapor pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lithium salt concentration is increased above 1-2 moles/liter to reduce volatility and flammability, then safety is improved, but the cost increases and lithium-ion conductivity decreases
Solution Approach 1:
The patent changes the concentration parameter of lithium salt from conventional 1-2 moles/liter to greater than 1 mole/liter (concentrated electrolyte), which fundamentally alters the solvent structure and reduces free solvent molecules. This parameter change simultaneously improves safety by reducing volatility and flammability while the patent addresses the cost and conductivity issues through additional modifications.
Solution Approach 2:
The patent creates a composite electrolyte system combining concentrated lithium salt with specific carbonate solvents and cyclic carbonates in optimized ratios. This composite approach allows the system to achieve both high safety (through concentrated salt reducing free solvent) and acceptable conductivity (through careful solvent selection and combination) while managing cost effectively.
2Reliability
If the lithium salt concentration is increased above 1-2 moles/liter to reduce volatility and flammability, then safety is improved, but lithium-ion conductivity decreases
Solution Approach 1:
The patent optimizes multiple parameters including lithium salt concentration (>1 mole/liter), solvent ratios (cyclic carbonate 10-50 vol%, chain carbonate 50-90 vol%), and additive compositions. These coordinated parameter changes achieve the dual goal of improving safety through concentrated salt while maintaining lithium-ion conductivity through optimized solvent composition and ratio.
Solution Approach 2:
The patent creates localized solvation structures where lithium ions are surrounded by specific solvent molecules in concentrated regions, while maintaining overall electrolyte fluidity. This local organization of solvent molecules around ions reduces free solvent (improving safety) while preserving ion mobility pathways (maintaining conductivity).
3Object-affected harmful factors
If the lithium salt concentration is increased above 1-2 moles/liter, then volatility and flammability are reduced, but viscosity increases
Solution Approach 1:
The patent balances the concentration parameter of lithium salt with solvent composition parameters (mixing cyclic and chain carbonates in specific ratios). This balancing act reduces free solvent molecules (lowering volatility and flammability) while the chain carbonate component maintains lower viscosity compared to pure cyclic carbonate, achieving both safety and fluidity goals.
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 approach reduces the volatility and flammability of the electrolyte, enhances the safety of lithium-ion battery cells, and maintains comparable viscosity and conductivity to conventional electrolytes, thereby improving rate capability, cycle life, and overall performance.
Implementation Method 1
diluted concentrated electrolytes that include both a concentrated active salt in a solvent and a diluent... concentrated active salt in the solvent to concentrations greater than 1 mole/liter... disperses the concentrate of the active salt and solvent into localized regions throughout the electrolyte... significantly reduces the amount of free solvent in the electrolyte and vapor pressure
Implementation Method 2
a diluent that disperses the salt and solvent into localized regions... disperses the concentrate of the active salt and solvent into localized regions throughout the electrolyte
Data Source
AI summary
An electrolyte for a lithium-containing battery cell is described. The electrolyte includes a solvent having at least one carbonate ester, and at least one lithium salt having a concentration ranging from 3 mol/liter to 15 mol/liter in the solvent. The electrolyte also includes a diluent that includes an aromatic fluorocarbon. In some embodiments, the solution of the at least one lithium salt and the solvent is a supersaturated solution for at least some operating temperatures of the battery cell. Also described are lithium-containing battery cells that include a positive electrode, a negative electrode, and the electrolyte.