Battery Cell Stack Corrosion Resistance via Cushion Member
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Solution Overview
Problem
In redox flow batteries, the electrical resistance between the current collector plate and the end bipolar plate increases due to repeated charging and discharging, degrading battery performance, primarily caused by electrolytic corrosion from water entry during pressure changes.
Innovation Solution
The battery cell stack design includes materials for the current collector plate and end bipolar plate with a corrosion potential difference of 0.35 V or less, and optionally a deformable cushion member, to prevent electrolytic corrosion and maintain low electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current collector plate and end bipolar plate are used in a battery cell stack, then electrical connection is established for current collection, but electrical resistance increases due to electrolytic corrosion from water entry during pressure changes
Solution Approach 1:
A cushion member is introduced as an intermediary component between the current collector plate and the end bipolar plate. This cushion member serves multiple functions: it maintains electrical connection stability, prevents direct contact that would lead to electrolytic corrosion, and accommodates pressure changes during battery operation. The cushion member acts as a mediator that resolves the contradiction between establishing electrical connection and preventing corrosion.
Solution Approach 2:
The cushion member is designed as a sacrificial component that can be easily replaced. It is positioned to absorb the harmful effects of pressure changes and potential corrosion, protecting the more valuable current collector plate and end bipolar plate. This approach follows the principle of using a less critical component to protect critical components.
2Duration of action of moving object
If pressure changes occur during charging and discharging cycles, then battery operation is enabled, but water enters the battery cell stack causing increased electrical resistance
Solution Approach 1:
The cushion member is pre-installed between the current collector plate and the end bipolar plate to provide protective cushioning before water entry or corrosion can occur. This pre-positioned cushioning element anticipates pressure changes and potential water intrusion, maintaining separation and preventing direct contact between metallic components that would lead to corrosion during charging and discharging cycles.
3Reliability
If materials with different corrosion potentials are used for current collector plate and end bipolar plate, then electrical connection is established, but galvanic corrosion occurs increasing electrical resistance
Solution Approach 1:
The cushion member serves as an intermediary barrier between the current collector plate and the end bipolar plate, which are made of materials with different corrosion potentials. By preventing direct contact between these dissimilar metals, the cushion member eliminates the galvanic couple that would otherwise cause galvanic corrosion, while still maintaining the necessary electrical connection for current collection.
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 configuration effectively suppresses the increase in electrical resistance between the current collector plate and the end bipolar plate, ensuring stable battery performance even with repeated charging and discharging cycles.
Implementation Method 1
a cushion layer (cushion member) which is deformable in the thickness direction is provided between a current collector plate and an end bipolar plate
Implementation Method 2
two members in contact with each other between the current collector plate and the end bipolar plate are made of materials such that, when an accelerated test satisfying the following conditions 1 to 3 is performed, the electrical resistance value between the current collector plate and the end bipolar plate after the accelerated test is 1.05 times or less the electrical resistance value between the current collector plate and the end bipolar plate before the accelerated test
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a battery cell stack in which the electrical resistance between a current collector plate and an end bipolar plate is unlikely to increase when charging and discharging are repeated. A battery cell stack includes a current collector plate electrically connected to each of a pair of end bipolar plates located at both ends in the stacking direction. In the battery cell stack, two members in contact with each other between the current collector plate and the end bipolar plate are made of materials such that, when an accelerated test satisfying the following conditions 1 to 3 is performed, the electrical resistance value between the current collector plate and the end bipolar plate after the accelerated test is 1.05 times or less the electrical resistance value between the current collector plate and the end bipolar plate before the accelerated test: Condition 1 is that a cycle includes applying pressure over one minute to achieve a predetermined pressure, maintaining the predetermined pressure for one minute, and bringing the predetermined pressure back to the atmospheric pressure over one minute; Condition 2 is that the predetermined pressure is set to be the atmospheric pressure + 0.1 MPa; and Condition 3 is that the number of cycles is set to 18.