Quasi-Solid Electrolyte for Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium metal and lithium-ion batteries face challenges such as dendrite formation, thermal runaway, and flammability issues due to volatile organic solvents, limiting their commercialization and safety, especially in lithium-sulfur cells, which require a non-flammable electrolyte with high energy density and long cycle life.
Innovation Solution
A non-flammable quasi-solid electrolyte is developed by dissolving a high concentration of lithium salt in an organic solvent, reducing vapor pressure and increasing the flash point, allowing for a safe and stable lithium battery with enhanced energy density and cycle life, suitable for lithium metal and lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic liquid solvents are used in the electrolyte to enable lithium ion transport, then the battery can operate with good ionic conductivity, but the electrolyte becomes flammable and volatile leading to thermal runaway
Solution Approach 1:
The patent changes the concentration parameter of lithium salt in the electrolyte from conventional low concentrations (0.5-2.0 M) to very high concentrations (5.0-20.0 M). This parameter change transforms the electrolyte from a flammable liquid to a non-flammable quasi-solid gel structure, eliminating thermal runaway while maintaining ionic conductivity through the high density of lithium ions available for transport
Solution Approach 2:
The patent creates a composite electrolyte system combining lithium salt, organic solvent, and gel-forming additive. This composite structure integrates the ionic conductivity of the lithium salt-solvent system with the structural stability and non-flammability of the gel network, achieving both good ionic transport and thermal safety
2Quantity of substance
If lithium metal is used as the anode to achieve high energy density, then the battery capacity increases significantly, but dendrites form during cycling causing internal shorting and thermal runaway
Solution Approach 1:
The patent changes the electrolyte physical state parameter from liquid to quasi-solid gel through very high lithium salt concentration. This parameter change modifies the interface properties between electrolyte and lithium metal anode, suppressing dendrite formation by providing a more uniform lithium ion flux distribution while maintaining high energy density through lithium metal anode
3Ease of operation
If conventional low concentration electrolyte is used to ensure good flowability and ionic conductivity, then the battery operates efficiently, but the electrolyte remains highly flammable and volatile
Solution Approach 1:
The patent changes the concentration parameter to very high levels (5.0-20.0 M lithium salt), which fundamentally alters the electrolyte's physical properties. The high concentration creates a quasi-solid gel structure that eliminates volatility and flammability while maintaining ionic conductivity through the abundant lithium ion population in the concentrated system
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 high-concentration lithium salt electrolyte suppresses flammability, facilitates lithium ion transport, and prevents dendrite growth, achieving high energy density and long cycle life in lithium batteries, addressing safety and performance concerns.
Implementation Method 1
removing a portion of the first liquid solvent to obtain said quasi-solid electrolyte having a final lithium salt concentration higher than the first concentration so that the electrolyte exhibits a vapor pressure less than 0.01 kPa when measured at 20° C.
Implementation Method 2
a flash point at least 20 degrees Celsius higher than the flash point of the first liquid solvent alone, a flash point higher than 150° C., or no detectable flash point
Implementation Method 3
dissolving a high concentration of lithium salt in an organic solvent, reducing vapor pressure and increasing the flash point, allowing for a safe and stable lithium battery with enhanced energy density and cycle life
Implementation Method 4
The high-concentration lithium salt electrolyte suppresses flammability, facilitates lithium ion transport, and prevents dendrite growth, achieving high energy density and long cycle life in lithium batteries
Data Source
AI summary
Provided is a method of producing a non-flammable quasi-solid electrolyte for a lithium battery, the method comprising (A) dissolving a lithium salt in a first liquid solvent to obtain a mixture having a first concentration of lithium salt less than 3.0 M (mole/L), but greater than 0.001M; and (B) removing a portion of the first liquid solvent to obtain the quasi-solid electrolyte having a final lithium salt concentration higher than the first concentration so that the electrolyte exhibits a vapor pressure less than 0.01 kPa when measured at 20° C., a vapor pressure less than 60% of the vapor pressure of the first liquid solvent alone, a flash point at least 20 degrees Celsius higher than a flash point of the first liquid solvent alone, a flash point higher than 150° C., or no detectable flash point.