Lead-Acid Battery Conductive Separator Layer for Deep-Discharge Life
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Solution Overview
Problem
Recent lead-acid batteries, particularly those used in vehicles with idling stop/start systems, face challenges when used in partial state of charge conditions, leading to deeper discharge depths and increased load demands, which result in reduced cycle life and performance.
Innovation Solution
The lead-acid battery design includes a positive electrode plate, a negative electrode plate with a Bi element content of 100 ppm to 300 ppm, a separator with a resin substrate, and a conductive layer between the negative electrode plate and the resin substrate, enhancing charge acceptability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Bi element is added to negative electrode material to improve charge acceptability, then charge acceptability is improved, but reaction uniformity in up-down direction deteriorates
Solution Approach 1:
The invention introduces a conductive layer with non-uniform thickness (thicker at edges, thinner at center) to create local quality differences that compensate for the non-uniform reaction distribution caused by Bi addition, thereby restoring overall reaction uniformity
Solution Approach 2:
The conductive layer is designed with asymmetric thickness distribution (different thickness at edge portions versus central portion) to counterbalance the symmetric non-uniformity induced by Bi element, creating a new asymmetric structure that achieves symmetric performance improvement
2Reliability
If Bi element content is increased to improve charge acceptability, then charge acceptability is improved, but impedance increases
Solution Approach 1:
The invention changes the thickness parameter of the conductive layer (creating gradient thickness) to optimize electrical conductivity distribution, thereby reducing overall impedance while maintaining the beneficial effects of Bi element addition
3Power
If discharge capacity is increased to meet higher load demands, then load capability is improved, but cycle life is reduced
Solution Approach 1:
The conductive layer with varying thickness creates local quality differences that promote uniform current and reaction distribution across the electrode, preventing localized degradation and extending cycle life even at high discharge capacities
Solution Approach 2:
The conductive layer is pre-configured with specific thickness distribution before battery operation to proactively prevent non-uniform reaction and degradation, thereby extending cycle life before degradation can occur
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 significantly improves the life performance of lead-acid batteries, especially under deep discharge conditions, by promoting uniform charge-discharge reactions and reducing impedance.
Implementation Method 1
a conductive layer is provided between the negative electrode plate and the resin substrate
Data Source
Figure 1
AI summary
Disclosed is a lead-acid battery including: a positive electrode plate; a negative electrode plate; a separator interposed between the positive electrode plate and the negative electrode plate; and an electrolyte solution, in which the positive electrode plate contains a positive electrode material, the negative electrode plate contains a negative electrode material, the negative electrode material contains a Bi element, a content of the Bi element in the negative electrode material is 100 ppm or more and 300 ppm or less on a mass basis, the separator includes a resin substrate, and a conductive layer is provided between the negative electrode plate and the resin substrate.