Bipolar Battery Through-Hole Sealing Against Liquid Junctions
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Solution Overview
Problem
Bipolar lead-acid storage batteries face performance deterioration due to corrosion of positive electrode lead foils by sulfuric acid in the electrolyte solution, leading to electrolyte infiltration and liquid junction issues, which can cause peeling and reduce battery life.
Innovation Solution
A bipolar storage battery configuration with a liquid junction prevention member placed in the vicinity of the through holes to prevent electrolyte solution infiltration, using a conductor and liquid junction prevention member to electrically connect the positive and negative electrodes, ensuring the electrolyte solution does not reach the negative electrode side, thereby reducing liquid junction occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive electrode lead foil is used to conduct electricity and provide structural support, then electrical conductivity and structural integrity are improved, but corrosion by sulfuric acid causes coating film formation and elongation leading to peeling and performance deterioration
Solution Approach 1:
A corrosion-resistant layer (such as plastic coating or corrosion-resistant metal plating) is applied as an intermediary between the positive electrode lead foil and the sulfuric acid electrolyte. This protective layer prevents direct contact between the acid and the lead foil, eliminating the corrosion reaction that causes coating film formation and elongation, thereby maintaining structural integrity and electrical conductivity over time
Solution Approach 2:
The positive electrode lead foil is constructed as a composite structure combining lead (for electrical conductivity) with a corrosion-resistant material layer (such as plastic coating or corrosion-resistant metal). This composite structure maintains the electrical functionality of lead while adding protection against sulfuric acid corrosion, preventing the harmful effects of acid attack
2Reliability
If through holes are provided in the substrate for electrical connection between positive and negative electrodes, then electrical conductivity is improved, but electrolyte solution infiltrates through the holes causing liquid junction and performance deterioration
Solution Approach 1:
The substrate is designed with differentiated properties: the bulk substrate material provides mechanical support and isolation, while specific localized regions (such as the inner walls of through holes or surrounding areas) are treated with acid-resistant materials or coatings. This local modification prevents electrolyte infiltration at critical interfaces without compromising the overall electrical connection function
Solution Approach 2:
An intermediary substance or structure (such as an acid-resistant coating, sealant, or barrier layer) is introduced at the through hole interfaces where the substrate contacts the positive and negative electrodes. This intermediary prevents electrolyte solution from infiltrating through the through holes while maintaining electrical conductivity through the intended paths
3Strength
If adhesive is used to bond lead foils to the substrate, then bonding strength is improved, but adhesive degradation from acid exposure and lead foil elongation cause peeling and electrolyte infiltration
Solution Approach 1:
A corrosion-resistant layer is applied to the lead foil surfaces that contact the adhesive, serving as a protective intermediary. This layer prevents sulfuric acid from degrading the adhesive and prevents lead foil elongation from directly stressing the adhesive bond, thereby maintaining bonding strength and preventing peeling over time
Solution Approach 2:
The lead foil-adhesive-substrate assembly is enhanced with composite protective layers that provide both corrosion resistance and mechanical stability. These composite structures protect the adhesive interface from acid attack and accommodate thermal expansion and electrochemical stresses without causing bond failure
Data Source
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AI summary
Even if growth occurs in a positive electrode due to corrosion by an electrolyte solution, the electrolyte solution is prevented from infiltrating into a through hole, and even if the electrolyte solution infiltrates into the through hole, the electrolyte solution is prevented from reaching a negative electrode side as much as possible to greatly suppress the occurrence of a liquid junction, so that battery performance is less likely to deteriorate, and the life is prolonged. There are provided: a cell member (110) including a positive electrode (111), a negative electrode (112), and an electrolyte layer (113) interposed between the positive electrode (111) and the negative electrode (112), the cell member being stacked and disposed at an interval; a space forming member (120) including a substrate (121) and a frame body (122); a through hole (121a) formed to penetrate between a positive electrode side and a negative electrode side in the space forming member (120); and a conductor (170) inserted into the through hole (121a) to electrically connect the positive electrode side and the negative electrode side, in which a liquid junction prevention member (180) is provided in at least one of a vicinity of an opening on the positive electrode side and a vicinity of an opening on the negative electrode side of the through hole (121a).