PTC Polymer Layer for Secondary Battery Thermal Runaway Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary batteries face issues with stability and potential hazards due to thermal runaway and thermal propagation, which current safety mechanisms fail to effectively address, posing risks such as uncontrolled temperature increase and hazardous chemical leakage.
Innovation Solution
A polymer composition that forms a polymer layer exhibiting a positive temperature coefficient (PTC) effect, allowing rapid transition between conductive and insulating states in response to temperature and voltage changes, thereby enhancing stability by suppressing additional current flow during abnormal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external safety mechanisms (pressure-limited valves, cell-to-cell fire extinguishers, thermal insulating materials) are equipped in electric vehicles, then fire resistance is improved, but response speed to thermal runaway and thermal propagation remains very slow
Solution Approach 1:
The patent applies parameter changes by utilizing the positive temperature coefficient (PTC) effect, where the polymer layer's electrical resistance changes dramatically with temperature. When temperature increases due to thermal runaway, the resistance increases exponentially, automatically suppressing current flow and stopping the thermal propagation process without requiring external detection or control systems.
Solution Approach 2:
The polymer layer provides self-service safety protection through its intrinsic PTC effect. The material automatically responds to temperature increases by changing its electrical properties, eliminating the need for external sensors, control systems, or manual intervention. The safety mechanism is embedded directly in the battery structure and activates autonomously when thermal runaway occurs.
2Reliability
If polymer layer with PTC effect is applied to secondary battery, then stability against thermal runaway is improved through rapid resistance increase, but device complexity increases
Solution Approach 1:
The polymer layer serves multiple functions simultaneously: it acts as a current collector for normal battery operation and as a thermal runaway protection layer when temperature increases. This multi-functionality eliminates the need for separate safety mechanisms, reducing overall device complexity while maintaining safety performance.
Solution Approach 2:
The polymer layer provides self-service safety protection through its intrinsic PTC effect. The material automatically responds to temperature increases by changing its electrical properties, eliminating the need for external sensors, control systems, or manual intervention. The safety mechanism is embedded directly in the battery structure and activates autonomously when thermal runaway occurs.
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 polymer layer ensures rapid resistance increase in abnormal states, securing stability against thermal runaway and thermal propagation while maintaining normal device operation, thus improving safety in secondary batteries.
Implementation Method 1
The polymer composition can form a polymer layer exhibiting a PTC (positive temperature coefficient) effect, and the PTC effect of the polymer layer can be very precisely controlled in response to a temperature and an external voltage
Implementation Method 2
Conductive polymers change their conductivity depending on doping and de-doping states
Data Source
Figure 1~2
AI summary
The present specification discloses a polymer composition. The polymer composition can form a polymer layer exhibiting a PTC (positive temperature coefficient) effect, and the PTC effect of the polymer layer can be very precisely controlled in response to a temperature and an external voltage. The polymer layer can very quickly exhibit at a necessary time a transition between a state exhibiting excellent electrical properties such as very low resistance and a state exhibiting insulator properties due to the increased resistance. Accordingly, the polymer layer is applied to various electronic/electric devices, so that in a normal state, it does not affect driving of the devices through excellent electrical properties, and in an abnormal state, it is possible to ensure stability through the rapid resistance increase. For example, the polymer layer is applied to a secondary battery to be converted into an insulator in an abnormal state, thereby suppressing additional current flow, whereby it is possible to secure excellent stability against risks caused by TR and TP, and the like. The present specification also discloses the polymer layer, and a current collector and a secondary battery, each comprising the same.