Chromium-Coated Lead Wire for Battery Corrosion and Adhesion
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Solution Overview
Problem
Conventional lead wires in power storage devices, such as lithium ion secondary batteries, face issues with corrosion resistance and adhesiveness due to water infiltration and reaction with electrolytic solutions, leading to separation from the container over time.
Innovation Solution
A lead wire with a film coating containing a trivalent chromium compound and a first metal, where the concentration ratio of the first metal to trivalent chromium is optimized between 0.01 and 4.0, enhancing corrosion resistance and adhesiveness through improved film formation and thermal fusion layer bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin is used to join the lead conductor and container by thermal fusion, then the battery elements are sealed, but the joining force decreases gradually with time due to water infiltration and corrosion
Solution Approach 1:
The patent applies composite materials by creating a multi-layer film structure comprising a first layer with trivalent chromium compound and first metal, and a second layer with trivalent chromium compound and second metal. This composite structure provides both corrosion resistance and thermal fusion bonding capability, resolving the contradiction between maintaining joining force and extending service life.
Solution Approach 2:
The patent changes the chemical composition parameters of the film by specifying precise concentration ratios: first metal to trivalent chromium compound (0.01-4.0), second metal to trivalent chromium compound (0.01-4.0), and chromium hydroxide proportion (0.3-0.9). These parameter optimizations ensure the film provides sufficient corrosion resistance while maintaining thermal fusion bonding strength over time.
2Reliability
If the lead conductor is exposed to water and electrolytic solution, then electrical conduction is achieved, but corrosion occurs due to hydrofluoric acid formation
Solution Approach 1:
The patent uses a thin film coating applied to the lead conductor surface that acts as a protective barrier against water and electrolytic solution infiltration. The film's flexible structure conformally coats the conductor while providing corrosion resistance through its specific chemical composition containing trivalent chromium compounds and metal hydroxides.
Solution Approach 2:
The film acts as an intermediary layer between the lead conductor and the corrosive environment (water and electrolytic solution). It prevents direct contact between the conductor and harmful substances while allowing the conductor to maintain its electrical function, thus resolving the contradiction between electrical conduction and corrosion resistance.
3Reliability
If a film with trivalent chromium compound is applied to the lead conductor, then corrosion resistance is improved, but adhesiveness to the thermal fusion layer must also be maintained
Solution Approach 1:
The patent creates a composite film structure where the first layer (trivalent chromium compound + first metal) provides corrosion resistance, while the second layer (trivalent chromium compound + second metal) provides thermal fusion bonding. This composite approach allows each layer to optimize for its specific function while working together as an integrated coating system.
Solution Approach 2:
The patent applies local quality by giving different regions of the film different compositions: the first layer is optimized for corrosion resistance with specific metal content, while the second layer is optimized for thermal fusion bonding with different metal content. Each local region of the film has tailored properties to fulfill its specific functional requirement.
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 lead wire achieves a high degree of corrosion resistance and adhesiveness, ensuring reliable performance over time by optimizing the concentration ratio of the first metal to trivalent chromium in the film coating and incorporating a thermal fusion layer.
Implementation Method 1
the lead conductor requires corrosion resistance, adhesiveness and the like
Implementation Method 2
The container and the lead conductor are joined by, for example, thermal fusion with a resin
Data Source
AI summary
A lead wire including a lead conductor and a film covering at least a part of a surface of the lead conductor, wherein the film includes a trivalent chromium compound and a first metal, and a ratio of a concentration of the first metal to a concentration of the trivalent chromium compound on a surface of the film is 0.01 or more and 4.0 or less.