Bipolar Lead-Acid Battery Substrate Roughness for Leak Blocking
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Solution Overview
Problem
Bipolar lead-acid storage batteries face issues with electrolyte solution leakage through through-holes, leading to short circuits and corrosion of current collector plates, which reduces battery performance and lifespan due to inadequate adhesion of high corrosion-resistant lead foils to active material layers.
Innovation Solution
The battery design incorporates substrates with specific surface roughness and adhesive fixation of lead foils to prevent electrolyte leakage and enhance adhesion between lead alloys and active material layers, using a granular structure for lead foils and controlled surface roughness to ensure effective bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead foils with high corrosion resistance are used as current collector plates, then corrosion resistance is improved, but adhesion to active material layers deteriorates
Solution Approach 1:
The lead foil is designed with different surface properties at different locations: the surface contact area with the active material layer is treated to enhance adhesion (through roughening or coating), while the bulk material maintains high corrosion resistance. This local differentiation allows the foil to simultaneously achieve both strong adhesion and corrosion resistance.
Solution Approach 2:
A composite structure is employed where a lead-based alloy foil (providing corrosion resistance) is combined with an adhesive layer or surface treatment (providing adhesion). The composite comprises the lead foil substrate and an adhesive interface, allowing each component to fulfill its specific function: the lead foil resists corrosion while the adhesive layer ensures strong bonding to the active material.
2Strength
If adhesive is applied to fix lead foils to substrates, then adhesion is improved, but electrolyte leakage through through-holes worsens
Solution Approach 1:
An adhesive layer serves as an intermediary substance between the lead foil and the substrate, filling the through-holes and creating a sealed interface. The adhesive acts as a mediator that both bonds the components together and blocks the leakage path, simultaneously achieving adhesion and leakage prevention through its filling and sealing function.
Solution Approach 2:
The adhesive forms a flexible sealing film over the through-holes and at the interface between the lead foil and substrate. This thin film structure conforms to the surface geometry and provides a continuous barrier that prevents electrolyte leakage while maintaining the flexibility needed for thermal expansion and contraction during battery operation.
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 design effectively prevents short circuits and improves adhesion, maintaining battery performance and extending the lifespan by suppressing electrolyte leakage and corrosion, while optimizing adhesive usage.
Implementation Method 1
the positive electrode current collector plate and the negative electrode current collector plate are fixed to surfaces of the main substrate close to the positive electrode and close to the negative electrode, respectively, with an adhesive layer
Implementation Method 2
At least one of a surface of a main substrate close to the positive electrode and a surface of the main substrate close to the negative electrode has a ten-point average roughness (RzJIS) of 30 μm or more and 104 μm or less
Data Source
AI summary
In a bipolar storage battery where a positive electrode current collector plate and a negative electrode current collector plate are electrically connected in a through-hole of a substrate and a plurality of cell members are electrically connected in series, even when an electrolytic solution moves between the current collector plate and the substrate, the electrolytic solution is prevented from easily reaching the through-hole of the substrate, preventing a short circuit. At least one of a bottom surface of a recess that is a surface of a main substrate close to a positive electrode or a bottom surface of a recess that is a surface of the main substrate close to a negative electrode, the main substrate being a substrate arranged between cell members, has a ten-point average roughness (RzJIS) of between 30 μm and 104 μm, inclusive, and a maximum height roughness (Rz) of 123 μm or less.