Polymer Film Current Collector for Short-Circuit Blocking
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Solution Overview
Problem
Lithium secondary batteries face issues with cell stability, short circuits, and overheating due to lithium dendrite growth, leading to reduced cycle life and safety concerns, necessitating the development of a current collector that can prevent short circuit currents and maintain battery safety while reducing thickness and weight.
Innovation Solution
A current collector for electrodes comprising a polymer film with a conductive material, such as aluminum, coated on its surface, which functions as an electrochemical fuse, reacting with the electrolyte to break and block short-circuit currents, thereby preventing overheating and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal foil current collector is used, then electrical conductivity is ensured, but the thickness and weight of the battery increase
Solution Approach 1:
The patent uses a composite structure consisting of a polymer film substrate combined with a conductive material coating (such as aluminum). This composite approach provides the necessary electrical conductivity through the conductive coating while the lightweight polymer substrate reduces overall weight compared to traditional metal foil current collectors.
Solution Approach 2:
The patent employs a thin polymer film as the base structure instead of thick metal foil. The polymer film provides mechanical support and insulation, while a thin conductive coating layer (typically nanometer to micrometer scale) provides electrical conductivity, significantly reducing the overall thickness and weight of the current collector.
2Weight of stationary object
If a polymer film with conductive material is used, then weight and thickness are reduced, but the ability to block short-circuit currents is compromised
Solution Approach 1:
The conductive material coating on the polymer film is designed to react with the electrolyte under short-circuit conditions, causing it to corrode or break and block the short-circuit current. This self-activating safety mechanism eliminates the need for separate safety components while maintaining lightweight construction.
Solution Approach 2:
The patent controls the thickness and composition parameters of the conductive material coating to optimize both electrical conductivity during normal operation and reactivity with electrolyte during short-circuit conditions. By carefully adjusting these parameters, the current collector maintains low weight while achieving effective short-circuit blocking through controlled material degradation.
3Reliability
If the conductive material thickness is increased, then conductivity is improved, but the response time to block short-circuit currents increases
Solution Approach 1:
The patent optimizes the thickness of the conductive material coating to a specific range that balances electrical conductivity and reaction speed. The coating is thin enough to react quickly with the electrolyte during short-circuit events but thick enough to provide sufficient conductivity during normal operation. This parameter optimization achieves both fast response and adequate conductivity.
Solution Approach 2:
The composite structure of polymer film plus thin conductive coating allows the system to achieve high conductivity through the conductive material while maintaining overall thinness for fast response. The polymer substrate provides mechanical integrity without impeding the rapid electrochemical reaction of the conductive coating with the electrolyte during short-circuit 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
The polymer-based current collector effectively reduces short-circuit currents and prevents overheating, improving battery safety and energy density by using a conductive material that reacts to block current flow when a short circuit occurs, thus addressing the stability and safety issues of lithium secondary batteries.
Implementation Method 1
the conductive material may react with the electrolyte to be corroded or broken along a thickness direction over an entire thickness of the conductive material
Data Source
AI summary
A current collector for electrodes according to an embodiment of the present disclosure may include a polymer film, and a conductive material provided on at least one surface of upper and lower surfaces of the polymer film, wherein the conductive material may have a function of an electrochemical fuse or a function of blocking a short-circuit current.