Lead Acid Battery Negative Electrode Corrosion Control
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Solution Overview
Problem
Lead-acid batteries experience corrosion of the lug portion of the negative electrode due to oxidation during charge-discharge cycles, which leads to breakage, especially in idling stop applications where the potential of the lug portion falls into a specific range causing corrosion.
Innovation Solution
A lead-acid battery design incorporating a negative electrode current collector made of a Pb alloy with specific Ca and Sn content, combined with a carbon material comprising two types of carbon with different particle sizes and a controlled powder resistance ratio, suppresses corrosion by maintaining the potential outside the corrosive range and enhancing conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbon materials are used in the negative electrode, then the battery structure is simple, but the lug portion corrosion occurs due to potential falling into corrosive range during charge-discharge cycles
Solution Approach 1:
The patent applies parameter changes by specifying precise particle size ranges for two different carbon materials (first carbon material: 3-10 μm, second carbon material: 15-30 μm) and controlling their powder resistance ratio (R2/R1 between 15-155). This parameter optimization maintains the negative electrode potential outside the corrosive range during charge-discharge cycles, effectively preventing lug portion corrosion while managing the complexity of using multiple carbon materials.
Solution Approach 2:
The patent employs composite materials by combining two distinct carbon materials with different particle sizes and electrical resistance characteristics. The first carbon material (3-10 μm) and second carbon material (15-30 μm) work synergistically to maintain appropriate potential levels and prevent corrosion, demonstrating how composite material composition can solve the corrosion problem while accepting increased material complexity.
2Reliability
If the negative electrode current collector uses standard Pb alloy composition, then manufacturing is simple, but corrosion occurs when potential falls into specific range during idling stop applications
Solution Approach 1:
The patent applies parameter changes by optimizing the alloy composition with specific ranges: Ca content of 0.03-0.10 mass% and Sn content of 0.05-0.15 mass%. This precise parameter control enhances corrosion resistance in idling stop applications by maintaining the electrode potential outside the corrosive range, while balancing the manufacturing complexity associated with controlling multiple alloying elements.
3Productivity
If single particle size carbon material is used, then material preparation is simple, but conductivity network formation is insufficient leading to poor low-temperature high-rate discharge performance
Solution Approach 1:
The patent applies parameter changes by introducing a bimodal particle size distribution with two distinct ranges: 3-10 μm for the first carbon material and 15-30 μm for the second carbon material. This parameter optimization creates an effective conductivity network that enhances low-temperature high-rate discharge performance, while accepting the increased complexity of preparing and controlling multiple particle size fractions.
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 solution significantly reduces corrosion of the lug portion and improves low-temperature high-rate discharge performance by forming a conductive network, preventing lead sulfate accumulation and maintaining conductivity.
Implementation Method 1
a carbon material containing a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm; a ratio of powder resistance R2 of the second carbon material to powder resistance R1 of the first carbon material: R2/R1 is 15 or more and 155 or less
Implementation Method 2
lead contained in the lug portion of the negative electrode is oxidized during discharge in charge-discharge cycles, but the oxidized lead is not completely reduced to lead during charge, and this repetition causes corrosion to gradually proceed
Implementation Method 3
the oxidized lead is not completely reduced to lead during charge
Data Source
Figure 1
AI summary
A lead-acid battery includes a negative electrode plate and a positive electrode plate. The negative electrode plate includes a negative electrode current collector and a negative electrode material containing a carbon material. The carbon material contains a first carbon material having a particle size of 32 µm or more, and a second carbon material having a particle size of less than 32 µm. A ratio of powder resistance R2 of the second carbon material to powder resistance R1 of the first carbon material: R2/R1 is 15 or more and 155 or less. The negative electrode current collector is composed of a Pb alloy containing more than 0.06 mass% and 0.15 mass% or less of Ca and 0.10 mass% or more and 0.80 mass% or less of Sn.