Copper Current Collector Oxide Layer for Battery Thermal Runaway
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current collectors with untreated copper substrates covered in an electroconductive layer comprising thermoplastic resin and electroconductive material exhibit a lower positive temperature coefficient resistance function compared to those with aluminum substrates, as the polymer chains of the thermoplastic resin are reduced by copper, leading to reduced expansion and lower resistance when heated.
Innovation Solution
A copper substrate with a copper oxide layer having an average oxygen content of 10.5 at % or more within 1.0 μm from the surface is oxidized and covered with a positive temperature coefficient resistance layer comprising thermoplastic resin and electroconductive material, mimicking the resistance function of an aluminum substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a copper substrate is used as the current collector, then the electrical conductivity and energy density are improved, but the positive temperature coefficient resistance function is reduced because the thermoplastic resin polymer chains are reduced by copper
Solution Approach 1:
An aluminum oxide layer is introduced as an intermediary between the copper substrate and the thermoplastic resin coating. This aluminum oxide layer prevents direct contact between copper and the thermoplastic resin, thereby preventing the reduction of polymer chains while allowing the copper substrate to maintain its electrical conductivity and energy density benefits
Solution Approach 2:
The current collector is designed as a composite structure with multiple layers: copper substrate, aluminum oxide intermediate layer, and thermoplastic resin coating with electroconductive material. This composite structure combines the advantages of copper (high conductivity) with the protective function of aluminum oxide, enabling both high energy density and reliable positive temperature coefficient resistance function
2Reliability
If aluminum substrate is used, then the positive temperature coefficient resistance function is maintained, but the energy density and electrical conductivity are reduced compared to copper substrate
Solution Approach 1:
The invention creates a composite current collector that combines copper substrate (providing high energy density and electrical conductivity) with aluminum oxide layer and thermoplastic resin coating (providing positive temperature coefficient resistance function). This composite structure achieves both high energy density and reliable thermal runaway prevention
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 approach provides a current collector with a positive temperature coefficient resistance function similar to aluminum substrates, effectively interrupting electron transfer and preventing overheating in batteries, thus safeguarding the battery and connected devices from inappropriate use.
Implementation Method 1
oxidizing the copper substrate by heat-treating the copper substrate at 160° C. or more in a presence of an oxidizing gas
Implementation Method 2
a positive temperature coefficient resistance layer comprising a thermoplastic resin and an electroconductive material and covering the copper oxide layer
Data Source
AI summary
A current collector in which, even in the case of using a copper substrate, an electroconductive layer comprising a thermoplastic resin and an electroconductive material and covering the copper substrate provides the same positive temperature coefficient resistance function as the case of using an aluminum substrate. The current collector may comprise: a copper substrate comprising a copper oxide layer that an average content of an oxygen element present within a thickness of 1.0 μm or less from a surface of the copper substrate, is 10.5 at % or more, and a positive temperature coefficient resistance layer comprising a thermoplastic resin and an electroconductive material and covering the copper oxide layer of the copper substrate.