Block Copolymer Electrolyte for Reversible Thermal Runaway Protection
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Solution Overview
Problem
Existing lithium-ion batteries face the challenge of irreversible ion flow blocking during thermal runaway, rendering them non-rechargeable even if the overheating is temporary, as existing solutions do not allow for reversible restoration of ion flow once the battery returns to normal temperature.
Innovation Solution
A heat-sensitive block copolymer electrolyte with soluble polymeric segments A and B, which increases viscosity and potentially gels at elevated temperatures, allowing for a reversible return to a liquid state when the temperature drops, thereby modulating ionic conductivity and viscosity as a function of temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator or redox shuttle molecule is used to block ion flow during thermal runaway, then battery safety is improved, but the battery becomes non-rechargeable due to irreversible blocking
Solution Approach 1:
The patent uses a block copolymer whose solubility and thus the electrolyte's viscosity and ionic conductivity change with temperature. At normal temperatures, the copolymer is insoluble and the electrolyte maintains good ionic conductivity for charging. At elevated temperatures during thermal runaway, the copolymer becomes soluble, increasing viscosity and blocking ion flow to prevent damage. When the battery cools down, the copolymer becomes insoluble again, restoring ionic conductivity and rechargeability.
Solution Approach 2:
The patent employs a block copolymer consisting of two distinct polymeric segments with different properties: one segment provides temperature-responsive solubility while the other maintains structural integrity. This composite polymer structure enables the electrolyte to exhibit dual behavior - conducting ions at normal temperatures and blocking ions at elevated temperatures - thereby resolving the contradiction between safety and rechargeability.
2Reliability
If the electrolyte viscosity is increased to block ion flow during overheating, then thermal runaway is prevented, but the battery cannot return to normal operation after cooling
Solution Approach 1:
The patent creates a dynamic system where the electrolyte's viscosity and ionic conductivity are not fixed but change in response to temperature variations. The block copolymer's temperature-dependent solubility causes the electrolyte to automatically adjust its properties: low viscosity and high conductivity at operating temperatures, high viscosity and low conductivity at thermal runaway temperatures. This dynamic behavior allows the battery to prevent thermal runaway while maintaining operational lifespan through reversible property changes.
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 solution effectively reduces ionic conductivity during overheating, preventing damage, and allows for the battery's restoration to normal operation once the temperature returns to safe levels, ensuring the battery remains rechargeable.
Implementation Method 1
at least one polymeric segment B having a temperature for dissolution 'T' in said electrolyte, the polymeric segments A and B being present in amounts sufficient to make possible an increase in the viscosity, preferably up to gelling of the electrolyte, at a temperature greater than or equal to the temperature 'T'
Implementation Method 2
the return of the electrolyte to a liquid state when the temperature of the battery falls back below 'T'
Implementation Method 3
an increase in the viscosity, preferably up to gelling of the electrolyte, at a temperature greater than or equal to the temperature 'T'
Data Source
AI summary
Electrolyte for a lithium-ion battery comprising at least one block copolymer, characterized in that said block copolymer comprises at least one polymeric segment A which is soluble in said electrolyte and at least one polymeric segment B having a temperature for dissolution “T” in said electrolyte, the polymeric segments A and B being present in amounts sufficient to make possible an increase in the viscosity of the electrolyte, preferably up to gelling of the electrolyte, at a temperature greater than or equal to the temperature “T”; the ionic conduction is produced by a solvent comprising the copolymer and lithium salts.