PTC Polymer-Coated Current Collector for Battery Short-Circuit Protection
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Solution Overview
Problem
Secondary batteries are prone to ignition or explosion due to short circuits caused by direct contact between positive and negative electrodes, especially under overcharging, high temperatures, or external shocks, leading to increased risk of thermal runaway and gas generation.
Innovation Solution
An electrode current collector with a polymer layer exhibiting a positive temperature coefficient (PTC) effect is introduced, which controls charge movement based on temperature, maintaining low resistance in normal conditions and increasing resistance in abnormal states to prevent short circuits and thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer layer with PTC effect is added to the current collector, then safety against short circuits and thermal runaway is improved, but device complexity increases
Solution Approach 1:
The polymer layer with PTC effect is integrated within the current collector structure, forming a nested configuration where the functional polymer layer is embedded within or on the current collector. This nesting approach allows the safety function to be incorporated without significantly increasing overall device complexity, as the polymer layer becomes an integral part of the existing current collector architecture rather than a separate external component.
Solution Approach 2:
The invention combines the current collector material with a polymer layer exhibiting PTC effect, creating a composite structure. This composite material approach integrates the electrical conductivity function of the current collector with the temperature-dependent resistance protection function of the polymer, achieving enhanced safety while maintaining structural integrity and electrical performance.
2Reliability
If the polymer layer increases resistance in abnormal states to prevent short circuits, then safety is improved, but electrical conductivity in normal operation may be affected
Solution Approach 1:
The polymer layer exhibits dynamic electrical resistance characteristics that change with temperature. In normal operating conditions at standard temperatures, the polymer maintains low resistance to ensure good electrical conductivity. When abnormal temperature increases occur, the polymer's resistance dynamically increases to prevent short circuits and thermal runaway, thus achieving adaptive protection without compromising normal operation.
Solution Approach 2:
The invention utilizes the temperature-dependent resistance parameter of the polymer layer to achieve protective functionality. By selecting a polymer with appropriate PTC characteristics, the resistance parameter changes in response to temperature variations, remaining low for good conductivity during normal operation and increasing to provide protection during abnormal conditions, thus resolving the contradiction between conductivity and safety.
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 stabilizes the electrode and secondary battery by preventing abnormal overcurrent, reducing the risk of heat generation and explosion, and maintaining stable electrical characteristics and oxidation potential.
Implementation Method 1
a polymer layer exhibiting a positive temperature coefficient (PTC) effect is introduced, which controls charge movement based on temperature, maintaining low resistance in normal conditions and increasing resistance in abnormal states
Data Source
AI summary
An electrode current collector that includes a current collector body and a polymer layer formed on the current collector body, where the polymer layer includes a copolymer containing a first thiophene unit having a hydrocarbon group with 10 or more carbon atoms and a second thiophene unit having a hydrocarbon group with 9 or less carbon atoms, and the electrode current collector can exhibit excellent electrical characteristics, including low resistance, in a normal state in a secondary battery or the like, and can ensure stability through an increase in resistance in an abnormal state. Also provided are uses of the electrode current collector.