Lead-Acid Current Collector Sheet Microstructure for Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The deterioration of lead-acid storage batteries, particularly bipolar lead-acid storage batteries, due to corrosion of the positive electrode current collector plate, which can lead to short circuits and reduced battery performance, is a significant challenge. The existing lead alloys face issues with corrosion resistance and handling, especially in high-temperature applications.
Innovation Solution
A current collector sheet made from a rolled sheet of a Pb-Ca-Sn-based alloy with a specific composition, where the tin content is between 1.0 and 1.9 mass%, calcium content is between 0.005 and 0.028 mass%, and the balance is lead and inevitable impurities, is used. This alloy is subjected to heat treatment to achieve a microstructure with a controlled number of crystal grains, enhancing corrosion resistance without the inclusion of Sr as a component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If early lead-calcium alloys with high calcium content (0.08% or more) and low tin content (0.35 to 0.5%) are used, then the positive electrode grids are rapidly hardened and easily handled and pasted onto plates, but Pb3Ca precipitates formed on top of Sn3Ca precipitates tend to harden the alloy and tend to lead to increased corrosion and growth of the positive electrode grids in high temperature applications
Solution Approach 1:
The patent modifies the alloy composition parameters by reducing calcium content to 0.02-0.05% (lower than conventional alloys) and optimizing tin content to 0.1-2.0%, along with adding silver (0.1-1.0%) and other elements. This parameter change resolves the contradiction by preventing excessive hardening and corrosion while maintaining adequate handling properties through controlled precipitation behavior.
Solution Approach 2:
The patent creates a composite alloy system combining lead with multiple elements (calcium, tin, silver, aluminum, manganese) in specific proportions. This composite material approach allows the alloy to exhibit both good handling characteristics and enhanced corrosion resistance through synergistic interactions between different precipitate phases and matrix structure.
2Reliability
If lead alloys with significantly low calcium content (0.02 to 0.05%) are used, then corrosion resistance is significantly improved, but the alloy is significantly soft, is difficult to handle, and is significantly slowly hardened
Solution Approach 1:
The patent compensates for the softness caused by low calcium content by adding silver (0.1-1.0%) and optimizing tin content (0.1-2.0%). These additional elements create precipitate phases that provide strengthening, maintaining adequate hardness and handling properties while preserving the low-corrosion benefit of reduced calcium content.
Solution Approach 2:
The patent adjusts multiple composition parameters simultaneously: low calcium (0.02-0.05%), optimized tin (0.1-2.0%), and added silver (0.1-1.0%). This multi-parameter optimization resolves the contradiction by achieving both low corrosion (from low calcium) and adequate hardness (from tin and silver precipitation hardening).
3Reliability
If lead alloys with significantly low calcium content (0.02 to 0.05%) and low tin content are used, then corrosion resistance is improved, but the alloy is difficult to handle and requires a special treatment for making a thin current collector plate
Solution Approach 1:
The patent optimizes the balance between calcium (0.02-0.05%), tin (0.1-2.0%), and silver (0.1-1.0%) to achieve adequate strength for thin plate manufacturing without requiring special treatments. This parameter optimization ensures the alloy has sufficient formability and hardness for conventional manufacturing processes while maintaining low corrosion resistance.
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 proposed solution effectively suppresses corrosion of the positive electrode current collector plate, improving the longevity and reliability of lead-acid batteries by maintaining the microstructural integrity and preventing the formation of through-holes, thus enhancing the battery's overall performance and preventing short circuits.
Implementation Method 1
The proposed solution effectively suppresses corrosion of the positive electrode current collector plate, improving the longevity and reliability of lead-acid batteries by maintaining the microstructural integrity
Implementation Method 2
The number of crystal grains having a grain size of 10 μm or more present in a range excluding top and bottom 10% in a thickness direction of the rolled sheet in an arbitrary cross section is 25 or more and 55 or less per area of 1 mm2 in the range
Data Source
AI summary
A positive electrode current collector plate, which is a current collector sheet for a lead-acid storage battery, includes a rolled sheet including a lead alloy in which a content ratio of tin (Sn) is between 1.0 mass % and 1.9 mass %, inclusive, a content ratio of calcium (Ca) is between 0.005 mass % and 0.028 mass %, inclusive, and a balance is lead (Pb) and inevitable impurities. A hole penetrating in a plate surface direction is not formed, and the number of crystal grains having a grain size of 10 μm or more present in a range excluding top and bottom 10% in a thickness direction of the rolled sheet in an arbitrary cross section is between 25 and 55, inclusive, per area of 1 mm2 in the range.