Microcapsule Thermal Retardant Release for Battery Safety
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Solution Overview
Problem
Existing thermal event retardants in batteries often interfere with electrochemical processes, and methods to prevent highly localized current conditions leading to thermal runaway are inadequate.
Innovation Solution
Incorporation of event triggerable materials, thermally expandable hollow polymer microspheres, shape memory polymers, and microcapsules containing thermal retardant chemical species to retard or prevent thermal runaway by expanding, releasing chemical retardants, or increasing electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrolyte additives that electrochemically polymerize under HLCC conditions are used to prevent thermal runaway, then thermal safety is improved, but electrical resistance increases and battery performance deteriorates
Solution Approach 1:
The patent applies preliminary action by incorporating intumescent materials and shape memory polymers into the separator that proactively respond to temperature increases before thermal runaway occurs. These materials expand or change shape in advance to close pores and block current paths, preventing the need for reactive polymerization that would increase resistance and harm performance.
Solution Approach 2:
The patent replaces the electrochemical polymerization mechanism with a mechanical response system. Intumescent materials and shape memory polymers provide passive mechanical expansion or shape change in response to temperature, physically blocking pores and current paths without requiring electrochemical reactions that would increase electrical resistance and degrade battery performance.
2Reliability
If thermal event chemical retardants are continuously present in the battery, then thermal runaway prevention is improved, but electrochemical processes are interfered with
Solution Approach 1:
The patent applies the taking out principle by extracting the thermal retardant function from the bulk electrolyte and placing it in discrete microcapsules distributed within the separator. The thermal retardant chemicals are removed from continuous contact with electrochemical processes and only released when needed, eliminating interference with normal battery operation while maintaining thermal protection.
Solution Approach 2:
The patent implements preliminary anti-action by pre-positioning microcapsules containing thermal retardant chemicals within the separator structure. These capsules remain dormant during normal operation and only release their contents when triggered by thermal events, providing protective action in advance of actual thermal runaway without interfering with ongoing electrochemical processes.
3Reliability
If the separator pores are closed off to prevent ion transport under HLCC conditions, then current passage is stopped, but ion transport is also blocked
Solution Approach 1:
The patent applies dynamics by using temperature-responsive materials that dynamically change the separator's pore structure based on operating conditions. At normal temperatures, pores remain open for ion transport. When thermal events occur, the intumescent materials expand or shape memory polymers change shape to dynamically close pores, preventing current passage only when needed while maintaining productivity during normal operation.
Solution Approach 2:
The patent implements parameter changes by utilizing materials that change their physical state or dimensions in response to temperature parameters. The separator's pore size and structure are dynamically adjusted through thermal expansion of intumescent materials or shape changes in memory polymers, allowing the system to transition between open (high ion transport) and closed (current blocked) states based on thermal conditions.
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
Effectively prevents thermal runaway by maintaining battery functionality and allowing controlled release of thermal retardants to manage temperature and current density, ensuring safety and operability.
Implementation Method 1
thermally expandable hollow polymer microspheres including a core material in the sphere having a low boiling point so that upon heating the shell softens and the core material expands sufficient to retard or prevent thermal runaway
Implementation Method 2
shape memory polymer comprising a low density, thermal expandable inorganic filler constructed and arranged to self-expand upon a sudden rise in temperature
Implementation Method 3
a thermal retardant chemical species contained within said microcapsule, wherein said microcapsule is adapted to release said chemical species upon being exposed to a triggering event either prior to or during an unstable rise in temperature
Data Source
AI summary
One embodiment includes a rechargeable charge storage device including a microcapsule disposed within said rechargeable charge storage device; and a thermal retardant chemical species contained within said microcapsule, wherein said microcapsule is adapted to release said chemical species upon being exposed to a triggering event either prior to or during an unstable rise in temperature of said charge storage device.