Quasi-Solid Electrolyte for Safe Lithium Metal 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 due to volatile organic solvents, limiting their commercialization and safety, especially in electric vehicle applications.
Innovation Solution
A non-flammable, high-concentration lithium salt-based electrolyte system is developed, where a lithium salt is dissolved in an organic solvent to create a quasi-solid electrolyte with a vapor pressure less than 0.01 kPa and a flash point higher than 150°C, suppressing flammability and enabling safe lithium ion transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If volatile organic solvents are used in the electrolyte, then lithium ion transport is enabled, but flammability and thermal runaway occur
Solution Approach 1:
The patent changes the concentration parameter of lithium salt in the electrolyte from conventional low concentrations (0.5-2 M) to high concentrations (3-10 M). This parameter change transforms the electrolyte from a flammable liquid to a non-flammable quasi-solid gel, eliminating the fire hazard while maintaining lithium ion conductivity. The high concentration of lithium salt forms a three-dimensional network structure that restricts solvent molecule movement and prevents flammability.
Solution Approach 2:
The patent creates a composite electrolyte system combining lithium salt, organic solvent, and additive in specific ratios. The lithium salt forms a gel-like network structure that composite with the organic solvent, transforming it from a simple liquid to a quasi-solid composite material with both ion transport capability and fire resistance. This composite structure integrates the benefits of liquid electrolytes (ion conductivity) and solid electrolytes (safety).
2Use of energy by moving object
If lithium metal is used as anode, then high energy density is achieved, but dendrite formation causes internal shorting
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to quasi-solid gel by increasing lithium salt concentration. This parameter change fundamentally alters the interface between electrolyte and lithium metal anode, suppressing dendrite formation through the gel's mechanical constraints and uniform ion distribution, while preserving the high energy density benefits of lithium metal.
3Object-affected harmful factors
If high concentration of lithium salt is used, then flammability is suppressed, but viscosity increases
Solution Approach 1:
The patent optimizes the concentration parameter of lithium salt to a specific high concentration range (3-10 M) that achieves the gel transition point. At this critical concentration, the electrolyte transforms from liquid to quasi-solid, achieving fire resistance. The viscosity increase is managed by selecting appropriate lithium salt types and organic solvents that balance gel structure formation with ion mobility.
Solution Approach 2:
The patent creates a composite electrolyte where lithium salt forms a three-dimensional network composite with organic solvent molecules. This composite structure provides the gel framework that suppresses flammability while the specific composition selection ensures adequate ion transport pathways, managing the viscosity-tradeoff.
4Reliability
If conventional electrolyte composition is used, then lithium ion transport is achieved, but thermal runaway occurs
Solution Approach 1:
The patent changes the compositional parameter by using high concentration of lithium salt (3-10 M) instead of conventional low concentrations. This compositional change raises the thermal stability of the electrolyte by forming a gel structure that resists thermal decomposition and prevents the thermal runaway chain reaction that occurs in conventional liquid electrolytes.
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 solution provides a safe and high-performing electrolyte system for lithium batteries, preventing dendrite growth, thermal runaway, and flammability, while maintaining high energy density and long cycle life, suitable for electric vehicle applications.
Implementation Method 1
a lithium salt is dissolved in an organic solvent to create a quasi-solid electrolyte
Implementation Method 2
enabling safe lithium ion transport
Data Source
AI summary
A rechargeable lithium cell comprising a cathode having a cathode active material, an anode having an anode active material, a porous separator electronically separating the anode and the cathode, a non-flammable quasi-solid electrolyte in contact with the cathode and the anode, wherein the electrolyte contains a lithium salt dissolved in a first organic liquid solvent with a concentration sufficiently high so that the electrolyte exhibits a vapor pressure less than 0.01 kPa when measured at 20° C., a flash point at least 20 degrees Celsius higher than the flash point of the first organic liquid solvent alone, a flash point higher than 150° C., or no flash point. This battery cell is non-flammable and safe, has a long cycle life, high capacity, and high energy density.